# Young-Seok Lee

> ECE Ph.D. Candidate at Seoul National University (Seoul, Republic of Korea)

Site: https://korbean-0311.github.io/

## About

I am a Ph.D. candidate in the Department of Electrical and Computer Engineering (ECE) at Seoul National University, co-advised by Prof. Sangwook Nam and Prof. Jungsuek Oh.
I have collaborated with industry partners — including Samsung Electronics on RF Wireless Power Transfer and LIG Nex1 on large-scale phased-array calibration. My broader research interests span RF and electromagnetic systems, with active topics including:
- RF Beam-forming
- RF Near-field Beam-focusing
- Wireless Power Transfer (WPT)
- Target detection
- Indoor localization
- Space solar power and power transmission

**Research keywords:** Wireless Power Transfer, RF Beam-forming, Near-field Beam-focusing, Target Detection, Indoor Localization, Space Solar Power

**External profiles:**
- ORCID: https://orcid.org/0000-0003-3342-3707
- Google Scholar: https://scholar.google.com/citations?user=yCXRScIAAAAJ&hl=en
- IEEE Xplore: https://ieeexplore.ieee.org/author/519065710555122
- Lab Homepage (Wave Fusion Lab): http://wfl.snu.ac.kr/

## Recent News

- **11 Feb 2026** — Joined research project of LIG Nex1 for calibration of ultra-large-scale digital array antennas for space surveillance radar! _(Project Lead)_
- **31 Oct 2025** — Selected as the Scholarship Recipient for Samsung Electronics Device Solution (DS), Foundry Division!
- **22 Jul 2025** — Journal accepted in IEEE Open Journal of Antennas and Propagation (OJAP)! _(Co-author)_
- **20 Jul 2025** — Journal accepted in IEEE Transactions on Antennas and Propagation (TAP)! _(Co-author)_
- **06 Jun 2025** — Journal accepted in IEEE Antennas and Wireless Propagation Letters (AWPL)! _(1st Author)_

## Publications & Awards

### International Journals — Under Review

- **[3] An End-to-End DC-to-DC Efficiency Optimization and Design Analysis for MIMO Wireless Power Transfer Systems**
  - Authors: Y.-S. Lee, T. Yoon, J. Oh, and S. Nam*
  - Venue: IEEE Transactions on Microwave Theory and Techniques (TMTT)
  - Tags: 1st Author
  - Notes: Major Revision

- **[2] Hardware-Aware MILP for Optimal End-to-End Efficiency in MISO WPT: Joint Optimization of Power Modes and Fault Tolerance**
  - Authors: T. Yoon, Y.-S. Lee, U. Park, M. Kim, S. Lee, S. Nam, and J. Oh*
  - Venue: IEEE Transactions on Microwave Theory and Techniques (TMTT)
  - Notes: Major Revision

- **[1] Amplitude Tapering-Aware Efficient Near-Field Array Wireless Power Transfer Using Multi-State Supply Switching**
  - Authors: T. Yoon, Y.-S. Lee, M. Kim, S. Lee, J. Lee, S. Nam, and J. Oh*
  - Venue: IEEE Open Journal of Antennas and Propagation (OJAP)
  - Notes: Submitted

### International Journals — Published

- **[5] Wideband Dual-Polarized Endfire Slotted Horn Antenna With Tightly Coupled Dipole and Monopole Probe Arrays**
  - Authors: S. Kim, Y.-S. Lee, and S. Nam*
  - Venue: IEEE Transactions on Antennas and Propagation (TAP)
  - Details: vol. 73, no. 11, pp. 8528–8535, Nov. 2025
  - DOI: https://doi.org/10.1109/TAP.2025.3592276
  - Keywords: 5G millimeter-wave (mmWave), Dual-polarized antenna, Endfire array antenna, Horn antenna, Tightly coupled dipole array (TCDA), Tightly coupled monopole probe array (TCMPA), Wideband antenna
  - Abstract: We present a novel wideband dual-polarized endfire array antenna for 5G millimeter-wave (mmWave) applications. The design combines a tightly coupled dipole array (TCDA) for horizontal polarization and a tightly coupled monopole probe array (TCMPA) with a slotted metal horn for vertical polarization to achieve wideband operation. The slotted metal horn enhances the radiation and impedance matching of the TCMPA and enables both polarizations to operate in the same aperture. Both the TCMPA and TCDA operate at 23.8–42.3 GHz (< −10 dB for broadside radiation, fractional bandwidth = 56%), covering the n258, n257, n261, and n260 bands in frequency range 2 (FR 2) specified by 3GPP. This wideband operation is enabled by the proposed polarization-selective reflectors that optimize the performance of both the TCMPA and TCDA. Under same-phase excitation, simulated array gains of the vertical and horizontal polarizations are 4–8 and 4.4–8.2 dBi, respectively; when scanning up to 45° from the array axis they degrade to 4.6–7.2 and 4.6–5.6 dBi. Experimental results for matching bandwidth, realized array gain, and radiation pattern are in good agreement with simulation.
  - BibTeX:
    ```bibtex
    @ARTICLE{11104955,
      author={Kim, Seongjung and Lee, Young-Seok and Nam, Sangwook},
      journal={IEEE Transactions on Antennas and Propagation},
      title={Wideband Dual-Polarized Endfire Slotted Horn Antenna With Tightly Coupled Dipole and Monopole Probe Arrays},
      year={2025},
      volume={73},
      number={11},
      pages={8528-8535},
      doi={10.1109/TAP.2025.3592276}}
    ```

- **[4] A Topology-Based Array Compensation Empowered by Equivalent Current Modeling of TM₁₀ Patch Antennas for Cross-Polarization Reduction**
  - Authors: T. Yoon, U. Park, M. Kim, S. Lee, Y.-S. Lee, S. Nam, and J. Oh*
  - Venue: IEEE Open Journal of Antennas and Propagation (OJAP)
  - Details: vol. 6, no. 6, pp. 1696–1707, Dec. 2025
  - DOI: https://doi.org/10.1109/OJAP.2025.3592198
  - Keywords: Cross-polarization suppression, Patch antenna, TM10 mode, Antenna array configuration, Equivalent current modeling, Series power divider, Beamforming
  - Abstract: This paper introduces a comprehensive analysis of cross-polarization effects originating from current imbalances in patch antennas and array configurations. A simplified yet broadly applicable mitigation strategy is proposed, offering a generalized approach to improve cross-polarization performance for antenna arrays operating in the TM10 mode. In contrast to earlier works that predominantly employed heuristic array rotation techniques, this work adopts a systematic modeling approach to elucidate and regulate cross-polarization across a wide range of array scales and topologies. By utilizing electric current modeling at both the single-element and array levels and analyzing radiation behavior in multiple planes, the beam pattern characteristics are thoroughly examined, and several optimized array configurations targeting cross-polarization suppression are proposed. The array system incorporates a series-type power divider, validated through both simulation and measurement, demonstrating significant cross-polarization suppression over all scan angles; the fabricated divider achieves amplitude and phase mismatches of less than 3 dB and 10 degrees across 16 output branches. The results establish a conceptual design methodology that achieves substantial cross-polarization reduction without altering individual element geometries, attaining a cross-polarization discrimination (XPD) level of −40 dB in beamforming scenarios.
  - BibTeX:
    ```bibtex
    @ARTICLE{11096003,
      author={Yoon, Taeyeong and Park, Uichan and Kim, Minje and Lee, Sanghun and Lee, Young-Seok and Nam, Sangwook and Oh, Jungsuek},
      journal={IEEE Open Journal of Antennas and Propagation},
      title={A Topology-Based Array Compensation Empowered by Equivalent Current Modeling of TM10 Patch Antennas for Cross-Polarization Reduction},
      year={2025},
      volume={6},
      number={6},
      pages={1696-1707},
      doi={10.1109/OJAP.2025.3592198}}
    ```

- **[3] Transmission-Conversion Efficiency Maximization Technique for MIMO Wireless Power Transfer Systems in ISAC Applications**
  - Authors: Y.-S. Lee, T. Yoon, Y. J. Song, S. K. Hong, J. Oh, and S. Nam*
  - Venue: IEEE Antennas and Wireless Propagation Letters (AWPL)
  - Details: vol. 24, no. 11, pp. 4492–4496, Nov. 2025
  - DOI: https://doi.org/10.1109/LAWP.2025.3578089
  - Tags: 1st Author
  - Keywords: Wireless power transfer (WPT), MIMO, Integrated sensing and communications (ISAC), Transmission-conversion efficiency (TCE), Power transfer efficiency (PTE), RF-to-DC rectifier, Near-field
  - Abstract: This letter presents a DC power optimization methodology for multiple-input–multiple-output (MIMO) wireless power transfer (WPT) systems, especially for integrated sensing and communications (ISAC) applications. Given a rectifier that has already been optimized, the transmission-conversion efficiency (TCE) is optimized by jointly considering both the RF–RF (air propagation) and RF–DC (rectifier) stages. In a specific MIMO WPT configuration with a 16×16 transmitter array and an 8×8 receiver array, simulation results show a significant 65.6% TCE improvement over conventional RF-to-RF power transfer efficiency optimization, offering a boundary for future real-time WPT algorithms.
  - BibTeX:
    ```bibtex
    @ARTICLE{11029126,
      author={Lee, Young-Seok and Yoon, Taeyeong and Song, Young Jin and Hong, Sun K. and Oh, Jungsuek and Nam, Sangwook},
      journal={IEEE Antennas and Wireless Propagation Letters},
      title={Transmission-Conversion Efficiency Maximization Technique for MIMO Wireless Power Transfer Systems in ISAC Applications},
      year={2025},
      volume={24},
      number={11},
      pages={4492-4496},
      doi={10.1109/LAWP.2025.3578089}}
    ```

- **[2] A Design and Characterization Method of a Scalable Large Transmitting Array for Wireless Power Transfer**
  - Authors: Y.-S. Lee, T. Yoon, M. Kim, S. Lee, B. Jung, J. Oh, and S. Nam*
  - Venue: IEEE Transactions on Microwave Theory and Techniques (TMTT)
  - Details: vol. 73, no. 6, pp. 3346–3358, Jun. 2025
  - DOI: https://doi.org/10.1109/TMTT.2024.3487911
  - Tags: 1st Author
  - Keywords: Wireless power transfer (WPT), Array calibration, Beam collection efficiency (BCE), Large transmitting array, Near-field focusing, Loss-compensated series power divider (LCSPD), Phased array
  - Abstract: This article presents a method for designing, characterizing, and calibrating a scalable transmitter with a large number of antenna elements, and for calculating the precise beam collection efficiency (BCE) in radio-frequency wireless power transfer (WPT) systems. Rather than simply applying conventional radar calibration methods to WPT systems, an efficient calibration technique is proposed that reduces calibration time while accurately estimating BCE. The method uses only a single connection at the transmitter array (TXA) input and a fixed reference antenna, maintaining a simple experimental setup while significantly reducing the required calibration time and space. To efficiently distribute RF signals in large array systems with minimal space, a loss-compensated series power divider (LCSPD) is presented. The approach is validated using an experimental prototype operating at 5.64 GHz, comprising a 256-element TXA and a 35-element receiver array (RXA). In a 0.5-m transmission scenario, a transmitted power of 6.08 W, received power of 4.37 W, and a BCE of 71.9% were achieved, underscoring the potential of near-field focusing in WPT systems and the accuracy of the proposed method.
  - BibTeX:
    ```bibtex
    @ARTICLE{10750830,
      author={Lee, Young-Seok and Yoon, Taeyeong and Kim, Minje and Lee, Sanghun and Jung, Byungwook and Oh, Jungsuek and Nam, Sangwook},
      journal={IEEE Transactions on Microwave Theory and Techniques},
      title={A Design and Characterization Method of a Scalable Large Transmitting Array for Wireless Power Transfer},
      year={2025},
      volume={73},
      number={6},
      pages={3346-3358},
      doi={10.1109/TMTT.2024.3487911}}
    ```

- **[1] Efficiency Bound Estimation for a Practical Microwave and mmWave Wireless Power Transfer System Design**
  - Authors: H. Y. Kim, Y.-S. Lee, and S. Nam*
  - Venue: Journal of Electromagnetic Engineering and Science (JEES)
  - Details: vol. 23, no. 1, pp. 69–74, Jan. 2023
  - DOI: https://doi.org/10.26866/jees.2023.1.r.146
  - Keywords: Microwave wireless power transfer (MPT), Wireless power transfer (WPT), Power transfer efficiency (PTE), Convex optimization, Array antenna, Active element pattern (AEP)
  - Abstract: We present an efficient method to find the power transfer efficiency (PTE) bound for practical microwave and mmWave wireless power transfer (MPT) systems composed of transmitter (Tx) and receiver (Rx) array antennas. The PTE bound is obtained by formulating it as a convex optimization problem that maximizes the power received at the Rx array under a transmit power constraint. The channel state information (CSI) between each Tx and Rx element is the input to the problem, estimated using the Friis transmission equation and the active element pattern of the array antenna under a large-array assumption. For MPT systems designed at 10 GHz and 24 GHz, the estimated PTE bound is compared with previous studies while varying the distance and tilt angle between Tx and Rx, and computation times are compared. Numerical results show that the proposed method provides a faster and more accurate PTE bound without full electromagnetic simulation, serving as a guideline for practical MPT system design.
  - BibTeX:
    ```bibtex
    @article{doi:10.26866/jees.2023.1.r.146,
      author={Kim, Ho Yeol and Lee, Youngseok and Nam, Sangwook},
      title={Efficiency Bound Estimation for a Practical Microwave and mmWave Wireless Power Transfer System Design},
      journal={J. Electromagn. Eng. Sci},
      volume={23},
      number={1},
      pages={69-74},
      year={2023},
      doi={10.26866/jees.2023.1.r.146},
      url={https://jees.kr/journal/view.php?number=3571}}
    ```

### International Conferences

- **[8] DC-to-DC Efficiency Maximization in Wireless Power Transfer with PA and Rectifier Nonlinearities via Semidefinite Relaxation**
  - Authors: Y.-S. Lee, T. Yoon, S. Nam, and J. Oh*
  - Venue: 2026 IEEE Wireless Power Technology Conference and EXPO (WPTCE 2026)
  - Details: Halifax, Canada, Jul. 4–7, 2026
  - Tags: 1st Author
  - Notes: Accepted
  - Keywords: Wireless power transfer (WPT), DC-to-DC efficiency, Power amplifier (PA) nonlinearity, Rectifier nonlinearity, Semidefinite relaxation (SDR), Transmission-conversion efficiency (TCE), Beamforming
  - Abstract: We propose an end-to-end DC-to-DC efficiency maximization framework for array-antenna RF-based wireless power transfer (WPT) that jointly accounts for transmit power amplifier (PA) and receive rectifier nonlinearities. While prior studies have mainly addressed PA and rectifier nonlinearities through waveform design, this work optimizes the practical CW excitation vector under measured device operating constraints, providing a practical way to determine the optimal transmit excitation for maximum end-to-end DC power delivery. Using measurement-based piecewise-linear (PWL) models for both PA and rectifier characteristics, we maximize the sum of rectified DC power at the receiver array under a transmit-side DC power budget. By applying semidefinite lifting, the problem admits an efficient semidefinite relaxation (SDR) that provides a tight upper bound and a high-quality feasible solution via rank-one recovery and local refinement. Simulation results show 38.3% higher received DC power than conventional RF-to-RF efficiency optimization, with a relaxation-to-feasible gap of 1.69%, and experiments confirm the framework with less than 8% error.

- **[7] Design and Calibration of a CW Time Reversal Wireless Power Transfer Transmitter with Pilot Signal Detection**
  - Authors: Y.-S. Lee, T. Yoon, J. Oh, and S. Nam*
  - Venue: 2025 Asia-Pacific Microwave Conference (APMC 2025)
  - Details: Jeju, Republic of Korea, Dec. 2–5, 2025
  - DOI: https://doi.org/10.1109/APMC65046.2025.11378159
  - Tags: 1st Author
  - Notes: Invited Paper
  - Keywords: Wireless power transfer (WPT), Array calibration, Time reversal (TR), Pilot signal detection, Retrodirective array, Continuous wave (CW), Look-up table (LUT)
  - Abstract: This paper presents a continuous-wave (CW) wireless power transfer (WPT) transmitter system capable of detecting pilot signals via a novel hardware calibration method, validated by a time reversal (TR) algorithm. The proposed transmitter architecture integrates a frequency-offset-based pilot signal detection scheme and compensates for all path-dependent distortions through a one-time calibration process. A look-up table (LUT) generated from simulation-derived ideal values enables accurate estimation of the pilot signal's magnitude and phase at the transmitter array (TXA). The system is implemented with a 16×16 TXA and a 5×5 receiver array (RXA), operating at 5.64 GHz with a 7 kHz pilot offset. Calibration and TR focusing performance are validated through experiments comparing measured and simulated results, providing a scalable and practical method for efficient WPT calibration in pilot-signal-based TR systems.
  - BibTeX:
    ```bibtex
    @INPROCEEDINGS{11378159,
      author={Lee, Young-Seok and Yoon, Taeyeong and Oh, Jungsuek and Nam, Sangwook},
      booktitle={2025 Asia-Pacific Microwave Conference (APMC)},
      title={Design and Calibration of a CW Time Reversal Wireless Power Transfer Transmitter with Pilot Signal Detection},
      year={2025},
      pages={1-3},
      doi={10.1109/APMC65046.2025.11378159}}
    ```

- **[6] Effects of Magnitude Dynamic Range Constraints on MIMO Wireless Power Transfer Efficiency**
  - Authors: Y.-S. Lee, J. Oh, and S. Nam*
  - Venue: 2025 International Symposium on Antennas and Propagation (ISAP 2025)
  - Details: Fukuoka, Japan, Oct. 27–31, 2025
  - DOI: https://doi.org/10.23919/ISAP63122.2025.11361879
  - Tags: 1st Author
  - Keywords: Wireless power transfer (WPT), MIMO, Power transfer efficiency (PTE), Power amplifier (PA), Dynamic range constraint, Doherty power amplifier, Convex optimization
  - Abstract: This paper studies the effect of magnitude dynamic range constraints on power transfer efficiency (PTE) in MIMO wireless power transfer (WPT) systems. Conventional optimized PTE patterns show highly impractical distributions across transmitter arrays (TXA), with extreme dynamic ranges unsuitable for real power amplifiers (PAs). By assuming an ideal Doherty PA, the proposed convex approach demonstrates that even with a tight range (e.g., 3 dB), PTE degradation remains minimal. These findings enable practical WPT implementations that, by considering power-added efficiency (PAE) with a Doherty PA, can potentially enhance end-to-end (DC-to-DC) system efficiency in real-world applications.
  - BibTeX:
    ```bibtex
    @INPROCEEDINGS{11361879,
      author={Lee, Young-Seok and Oh, Jungsuek and Nam, Sangwook},
      booktitle={2025 International Symposium on Antennas and Propagation (ISAP)},
      title={Effects of Magnitude Dynamic Range Constraints on MIMO Wireless Power Transfer Efficiency},
      year={2025},
      pages={1-2},
      doi={10.23919/ISAP63122.2025.11361879}}
    ```

- **[5] Overcoming Efficiency Degradation in Wireless Power Transfer Systems: A Supply Voltage Modulation Method Empowered by 5.64-GHz 256-Element Antenna Array Receiving 10.6-Watt**
  - Authors: T. Yoon, Y.-S. Lee, M. Kim, S. Lee, J. Lee, S. Nam, and J. Oh*
  - Venue: 2025 IEEE/MTT-S International Microwave Symposium (IMS 2025)
  - Details: San Francisco, CA, USA, Jun. 15–20, 2025
  - DOI: https://doi.org/10.1109/IMS40360.2025.11104047
  - Keywords: Wireless power transfer (WPT), Supply voltage modulation, Transmitter efficiency, Convex optimization, Time reversal (TR), Amplitude tapering, Large antenna array
  - Abstract: This paper proposes a supply voltage switching method for a 16×16 large-scale array system operating at 5.64 GHz to efficiently receive RF power while considering transmitter hardware efficiency — a factor not extensively addressed in previous wireless power transfer (WPT) research. The study improves both transmitter efficiency and free-space efficiency. Free-space efficiency is optimized by determining each element's transmission amplitude and phase through convex optimization; however, this requires amplitude tapering of about 50 dB or more, which degrades transmitter efficiency. To address this, techniques are proposed to enhance the product of the two efficiencies, validated experimentally with an implemented system. Comparing the commonly used time-reversal (TR) pattern with the proposed convex pattern, the method improves free-space efficiency from 62% to 78% ideally, and the measured received power was 10.6 W for a 5×5 array configuration at 0.5 m.
  - BibTeX:
    ```bibtex
    @INPROCEEDINGS{11104047,
      author={Yoon, Taeyeong and Lee, Young-Seok and Kim, Minje and Lee, Sanghun and Lee, Jaesup and Nam, Sangwook and Oh, Jungsuek},
      booktitle={2025 IEEE/MTT-S International Microwave Symposium - IMS 2025},
      title={Overcoming Efficiency Degradation in Wireless Power Transfer Systems: A Supply Voltage Modulation Method Empowered by 5.64-GHz 256-Element Antenna Array Receiving 10.6-Watt},
      year={2025},
      pages={85-88},
      doi={10.1109/IMS40360.2025.11104047}}
    ```

- **[4] Sequential Feedback-Based Phase Optimization Using Hadamard Basis for Wireless Power Transfer**
  - Authors: Y.-S. Lee, J. Oh, and S. Nam*
  - Venue: 2025 IEEE Wireless Power Technology Conference and EXPO (WPTCE 2025)
  - Details: Rome, Italy, Jun. 3–6, 2025
  - DOI: https://doi.org/10.1109/WPTCE62521.2025.11062191
  - Tags: 1st Author
  - Notes: Selected for Ph.D. Students Initiative Program
  - Keywords: Wireless power transfer (WPT), Phase optimization, Hadamard matrix, Feedback-based algorithm, Phased array, Power transfer efficiency (PTE), Beam-scanning
  - Abstract: Wireless power transfer (WPT) is a promising technology for efficient energy delivery to devices at long distances. A major challenge lies in searching the optimized phase pattern of transmitter arrays (TXAs) due to the vast number of possible phase combinations. This paper introduces a low-complexity algorithm that employs the orthogonal basis of Hadamard matrices to streamline the search for optimal phase distributions. By leveraging the orthogonality of Hadamard matrices, the proposed method achieves efficient iterative phase optimization with minimal hardware requirements, focusing only on phase adjustments to maximize received RF power at the receiver array. Simulation and experimental results validate the effectiveness, feasibility, and simplicity of the proposed approach.
  - BibTeX:
    ```bibtex
    @INPROCEEDINGS{11062191,
      author={Lee, Young-Seok and Oh, Jungsuek and Nam, Sangwook},
      booktitle={2025 IEEE Wireless Power Technology Conference and Expo (WPTCE)},
      title={Sequential Feedback-Based Phase Optimization Using Hadamard Basis for Wireless Power Transfer},
      year={2025},
      pages={1-5},
      doi={10.1109/WPTCE62521.2025.11062191}}
    ```

- **[3] An Effect of Time Reversal Based Multiple Beacon Selection on Wireless Power Transfer Performance**
  - Authors: Y.-S. Lee, J. Oh, and S. Nam*
  - Venue: 2024 International Symposium on Antennas and Propagation (ISAP 2024)
  - Details: Incheon, Republic of Korea, Nov. 5–8, 2024
  - DOI: https://doi.org/10.1109/ISAP62502.2024.10846697
  - Tags: 1st Author
  - Notes: Best Paper Award, 2nd Prize
  - Keywords: Wireless power transfer (WPT), Time reversal (TR), Multiple beacon selection, RF-to-DC efficiency, Near-field focusing, Array antenna
  - Abstract: This paper investigates the effectiveness of multiple-beacon (multi-beacon) systems in wireless power transfer (WPT), focusing on improving overall RF-to-DC efficiency. Through simulations in a 5.64 GHz scenario, limiting the dynamic range of TXA element radiation power to a maximum of 20 dBm and using an RXA rectifier within a specific range, multi-beacon configurations significantly enhanced RF-to-DC efficiency compared to single-beacon setups. The results showed 43.07% RF-to-DC efficiency and an RXA DC power of 1.20 W at 0.5 m, compared to 13.49% and 2.40 W for a single-beacon configuration. Trade-offs are evident: while multi-beacon systems bring higher RF-to-DC efficiency, they degrade absolute power and require greater hardware complexity, underscoring the importance of adaptive beacon selection considering the dynamic range specifications of both TXA and RXA.
  - BibTeX:
    ```bibtex
    @INPROCEEDINGS{10846697,
      author={Lee, Young-Seok and Oh, Jungsuek and Nam, Sangwook},
      booktitle={2024 International Symposium on Antennas and Propagation (ISAP)},
      title={An Effect of Time Reversal Based Multiple Beacon Selection on Wireless Power Transfer Performance},
      year={2024},
      pages={1-2},
      doi={10.1109/ISAP62502.2024.10846697}}
    ```

- **[2] LUT-Based Transmit Mode Calibration Complexity Reduction Method for Wireless Power Transfer**
  - Authors: Y.-S. Lee, T. Yoon, S. Lee, M. Kim, J. Lee, J. Oh, and S. Nam*
  - Venue: 2024 IEEE Wireless Power Technology Conference and Expo (WPTCE 2024)
  - Details: Kyoto, Japan, May 8–11, 2024
  - DOI: https://doi.org/10.1109/WPTCE59894.2024.10557392
  - Tags: 1st Author
  - Notes: Selected for Student Travel Grant
  - Keywords: Wireless power transfer (WPT), Array calibration, Look-up table (LUT), Large array antenna, Convex optimization, Near-field focusing
  - Abstract: This paper introduces a calibration method for transmitter arrays in the power transmit mode of wireless power transfer (WPT) systems. Focusing on the challenges posed by non-uniform power distribution in large array antenna systems, we propose a technique adaptable to various power distribution designs that also simplifies the calibration process, making it feasible for real-world applications with large array antennas. The paper validates the methodology from the hardware system to experimental results, demonstrating its effectiveness by transmitting convex-optimized (CVX) radiation patterns; the receiver array achieved a received RF power of 3.57 W at 0.5 m.
  - BibTeX:
    ```bibtex
    @INPROCEEDINGS{10557392,
      author={Lee, Young-Seok and Yoon, Taeyeong and Lee, Sanghun and Kim, Minje and Lee, Jaesup and Oh, Jungsuek and Nam, Sangwook},
      booktitle={2024 IEEE Wireless Power Technology Conference and Expo (WPTCE)},
      title={LUT-Based Transmit Mode Calibration Complexity Reduction Method for Wireless Power Transfer},
      year={2024},
      pages={137-141},
      doi={10.1109/WPTCE59894.2024.10557392}}
    ```

- **[1] Test Count Reduction Algorithm for Determining the Optimal Phase in Wireless Power Transfer using Bayesian Optimization**
  - Authors: Y.-S. Lee and S. Nam*
  - Venue: XXXVth URSI General Assembly and Scientific Symposium (URSI GASS 2023)
  - Details: Sapporo, Japan, Aug. 19–26, 2023
  - Tags: 1st Author

### Domestic Conferences (KIEES)

- **[6] End-to-End DC Power Optimization in Wireless Power Transfer Systems**
  - Authors: Y.-S. Lee, T. Yoon, S. Nam, and J. Oh*
  - Venue: 2026 KIEES Winter Conf.
  - Details: Feb. 2026
  - Tags: 1st Author

- **[5] MILP-based Optimal Beamforming in MISO WPT System: Dealing with Nonlinear Power Consumption and Discrete Voltage Rails**
  - Authors: T. Yoon, Y.-S. Lee, and J. Oh*
  - Venue: 2026 KIEES Winter Conf.
  - Details: Feb. 2026
  - Notes: Best Paper Award, IEEE MTT-S Seoul Chapter Award

- **[4] Received DC Power Maximization in a Practical Wireless Power Transfer Systems**
  - Authors: Y.-S. Lee, T. Yoon, J. Oh, and S. Nam*
  - Venue: 2025 KIEES Winter Conf.
  - Details: Feb. 2025
  - Tags: 1st Author
  - Notes: Best Paper Award, 1st Place

- **[3] Comprehensive Optimization of Beamforming Wireless Power Transfer: Achieving 500W Power Saving through Hardware-Aware Convex Method and Supply Voltage Modulation**
  - Authors: T. Yoon, Y.-S. Lee, M. Kim, S. Lee, and J. Oh*
  - Venue: 2025 KIEES Winter Conf.
  - Details: Feb. 2025

- **[2] RF-to-DC Efficiency Enhancement in Wireless Power Transfer Systems via Convex Optimization**
  - Authors: Y.-S. Lee, S. Nam, and J. Oh*
  - Venue: 2024 KIEES Summer Conf.
  - Details: Aug. 2024
  - Tags: 1st Author

- **[1] Multi-Receiver Charging Algorithm in Microwave Wireless Power Transfer**
  - Authors: H. Y. Kim, Y.-S. Lee, and S. Nam*
  - Venue: 2021 KIEES Autumn Conf.
  - Details: Nov. 2021

### Patents

- **[2] METHOD FOR DETERMINING OPTIMAL PHASES OF ANTENNA ARRAY IN RECONFIGURABLE INTELLIGENT SURFACE AND RIS SYSTEM USING THE SAME** (Korea)
  - Inventors: S. Nam and Y.-S. Lee
  - Patent No.: 1027047370000
  - Granted: 2024.09.04

- **[1] METHOD FOR DETERMINING OPTIMAL PHASES OF ANTENNA ARRAY IN TRANSMISSION ANTENNA AND A BEAM FOCUSING ARRAY SYSTEM USING THE SAME** (Korea)
  - Inventors: S. Nam and Y.-S. Lee
  - Patent No.: 1026925510000
  - Granted: 2024.08.01

### Awards

#### Conferences

- Best Paper Award (IEEE MTT-S Seoul Chapter Award) — 2026 KIEES Winter Conference, Feb. 2026

- Best Paper Award (1st Place) — 2025 KIEES Winter Conference, Feb. 2025  [1st Author]

- Best Paper Award (2nd Prize) — 2024 International Symposium on Antennas and Propagation (ISAP 2024), Nov. 2024  [1st Author]

#### Grants & Scholarships

- Ph.D. Students Initiative Program — 2025 IEEE Wireless Power Transfer Conference and Expo (WPTCE 2025), Jun. 2025  [1st Author]

- Student Travel Grant — 2024 IEEE Wireless Power Transfer Conference and Expo (WPTCE 2024), May 2024  [1st Author]

#### Student Paper Competitions

- Excellence Award — KIEES 9th Electromagnetic Measurement Paper Competition, Mar. 2024  [1st Author]

#### Invited Papers

- Invited Paper — 2025 Asia-Pacific Microwave Conference (APMC 2025), Dec. 2025  [1st Author]

## Education

### Seoul National University (SNU) (Seoul, Republic of Korea)
- Period: 2023.09 — Present
- Degree: Ph.D. in Electrical and Computer Engineering
- PI (Co-advised): Sangwook Nam
- PI (Co-advised): Jungsuek Oh (Ph.D. @Univ. of Michigan under Kamal Sarabandi)

### Seoul National University (SNU) (Seoul, Republic of Korea)
- Period: 2021.09 — 2023.08
- Degree: M.S. in Electrical and Computer Engineering
- PI: Sangwook Nam (Ph.D. @Univ. of Texas Austin under Tatsuo Itoh)

### Korea University (KU) (Seoul, Republic of Korea)
- Period: 2017.03 — 2021.08
- Degree: B.S. in Electrical Engineering
- Advisor: Chulwoo Kim

### Daejeon Dongsin Science High School (DDSHS) (Daejeon, Republic of Korea)
- Period: 2014.03 — 2017.02

## Research

### Graduate Student

*Affiliation:* AEL (PI: Sangwook Nam) & WFL (PI: Jungsuek Oh) at Seoul National University (jointly advised)

#### [P5] Calibration Verification and Accuracy Improvement of Ultra-Large-Scale Digital Array Antennas
- Organization: LIG Nex1
- Period: 2026.04 — 2028.12
- Keywords: Space Surveillance Radar, Ultra-Large-Scale Digital Array Antenna, Fixed Probe Calibration, Phase Center Compensation, Beam Pattern Modeling
- Summary:
  - Developed calibration and verification algorithms for ultra-large-scale digital array antennas (86,400+ elements) used in space surveillance radar, addressing major error sources (probe phase center offset, polarization misalignment, position-dependent element beam patterns, 3D probe position uncertainty, and radome-induced channel distortion).
  - Designed an AI-integrated calibration verification simulator enabling independent and combined sensitivity analysis of error sources, providing quantitative performance evaluation and optimal calibration strategies for field-deployed large-aperture phased array systems.

#### [P4] Large-Area Wireless Power Transfer System for Power Gateway Application
- Organization: Samsung Electronics A-Lab
- Period: 2023.09 — 2024.02
- Keywords: RF-Wireless Power Transfer, Large Array Calibration, Beam Collection Efficiency, Near-Field Focusing, High-Power Scalable Array
- Summary:
  - Scaled up the LUT-based calibration and LCSPD architecture to a 1024-element (32×32) transmitter and 256-element (16×16) receiver array operating at 5.64 GHz for power gateway applications.
  - Designed and validated high-power WPT system operation exceeding 100 W transmitted power, demonstrating the scalability of the proposed calibration and series power divider methodology.

#### [P3] High-Efficiency BCE 2D Array RF System Based on Time Reversal
- Organization: Samsung Electronics A-Lab
- Period: 2023.03 — 2023.08
- Keywords: RF-Wireless Power Transfer, Array Calibration, Beam Collection Efficiency, Near-Field Focusing, Scalable Array Design
- Summary:
  - Proposed an LUT-based calibration and complexity reduction method for a scalable 256-element transmitter array in RF wireless power transfer systems, enabling accurate beam collection efficiency (BCE) estimation using only a single input connection and a fixed reference antenna.
  - Designed a loss compensated series power divider (LCSPD) for scalable RF signal distribution and demonstrated 71.9% BCE at 0.5 m with 6.08 W transmitted and 4.37 W received power at 5.64 GHz, validated through convex-optimized near-field focusing experiments.

#### [P2] Wireless Power Transfer Using Massive MIMO Microwave with Hybrid Beamforming
- Organization: Samsung DS
- Period: 2023.03 — 2023.09
- Keywords: Feedback based algorithms, RF-Wireless Power Transfer, Array antenna, RF System
- Summary:
  - Received power feedback based RF-WPT optimization algorithm.

#### [P1] Wireless Power Transfer System Design
- Organization: Samsung Research (SR)
- Period: 2021.08 — 2022.07
- Keywords: RF-Wireless Power Transfer, Array antenna, mmWave antenna, RF System, Link-budget
- Summary:
  - Design and fabrication of mmWave large array transmitter antenna (@24 GHz, 32×32).

### Undergraduate Student Intern

#### AEL (Advisor: Sangwook Nam) , Seoul National University (2021.01 — 2021.08)
- RADAR system used DC to DC SMPS (36 W) PCB design & artwork
- Trained circuit design tools (OrCAD)

#### AISL (Advisor: Chulwoo Kim) , Korea University (2020.03 — 2020.06)
- Bachelor's Thesis: "High-speed 2-Stage Cascode Op-amp Design"
- Simple VCO, PLL design
- Trained circuit design tools (Cadence Virtuoso)

#### BASIC Lab. (Advisor: Hyungmin Lee) , Korea University (2019.12 — 2020.02)
- 2-Stage amp design & trained circuit design tools (Cadence Virtuoso)

## Others

### Reviewer Activities
- IEEE TPEL, 2025, 2026

### Scholarships
- Ph.D. Scholarship Recipient — Samsung Electronics Device Solution (DS), Foundry Division (Sep. 2025 -)
- Teaching & Research Support Scholarship — Seoul National University (Feb. 2023)
- Academic Excellence Scholarship — Seoul National University (Jan. 2022)

### Teaching Assistant
- Introduction to Electromagnetism with Practice (430.202B 003), Seoul National University, Fall 2025
- Introduction to Electromagnetism with Practice (430.202B 002), Seoul National University, Fall 2024
- Electromagnetic Wave Engineering (430.464A 001), Seoul National University, Spring 2023

### Selected Coursework
**Coursework in SNU (M.S. - Ph.D):**
- Electromagnetic Wave Engineering
- RF System Design
- Advanced Electromagnetics I
- Deep Learning _(NVIDIA DLI Course)_
- Machine Learning & Deep Learning
- Digital Signal Processing
- Electro-optics
- Estimation Theory

**Coursework in KU (B.S.):**
- Probability & Random Process
- Electromagnetics
- Electromagnetic Field
- Analog / Digital Communication Theory
- Digital Signal Processing
- Wireless Networks

### Programming Skills
**Programming Languages:**
- C (3.5/5)
- Python (3/5)
- MATLAB (4.5/5)

**Hardware Tools:**
- *EM Simulators*: Dassault System CST (4/5), Ansys HFSS (2.5/5), Keysight ADS (3/5), Altair FEKO Suite (3/5)
- *Circuit Tools*: Cadence OrCAD Capture (4/5), Cadence Allegro (3.5/5), Cadence Virtuoso (3/5)

## Contact

- ORCID: https://orcid.org/0000-0003-3342-3707
- Google Scholar: https://scholar.google.com/citations?user=yCXRScIAAAAJ&hl=en
- Lab: Wave Fusion Lab — http://wfl.snu.ac.kr
- LinkedIn: https://www.linkedin.com/in/korbean
- Location: INMC, Bldg #132, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of Korea

_Email omitted; please reach out via LinkedIn or the lab homepage._

---
_Generated automatically from data/*.json on 2026-06-08._