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A Fully Integrated Dual-Band WLP CMOS Power Amplifier for 802.11n WLAN Applications
Seungjun Baek,Hyunjin Ahn,Hyunsik Ryu,Ilku Nam,Deokgi An,Doo-Hyouk Choi,Mun-Sub Byun,Minsu Jeong,Bo-Eun Kim,Ockgoo Lee 한국전자파학회JEES 2017 Journal of Electromagnetic Engineering and Science Vol.17 No.1
A fully integrated dual-band CMOS power amplifier (PA) is developed for 802.11n WLAN applications using wafer-level package (WLP) technology. This paper presents a detailed design for the optimal impedance of dual-band PA (2 GHz/5 GHz PA) output transformers with low loss, which is provided by using 2:2 and 2:1 output transformers for the 2 GHz PA and the 5 GHz PA, respectively. In addition, several design issues in the dual-band PA design using WLP technology are addressed, and a design method is proposed. All considerations for the design of dual-band WLP PA are fully reflected in the design procedure. The 2 GHz WLP CMOS PA produces a saturated power of 26.3 dBm with a peak power-added efficiency (PAE) of 32.9%. The 5 GHz WLP CMOS PA produces a saturated power of 24.7 dBm with a PAE of 22.2%. The PA is tested using an 802.11n signal, which satisfies the stringent error vector magnitude (EVM) and mask requirements. It achieved an EVM of -28 dB at an output power of 19.5 dBm with a PAE of 13.1% at 2.45 GHz and an EVM of -28 dB at an output power of 18.1 dBm with a PAE of 8.9% at 5.8 GHz.
Enhanced methane hydrate formation with cyclopentane hydrate seeds
Baek, Seungjun,Ahn, Yun-Ho,Zhang, Junshe,Min, Juwon,Lee, Huen,Lee, Jae W. Elsevier 2017 APPLIED ENERGY Vol.202 No.-
<P>This work presents the kinetic promotion effect of sll cyclopentane (CP) hydrate seeds on sI CH4 hydrate formation in sodium dodecyl sulfate (SDS) solutions. Gas hydrates are one of the promising materials for natural gas storage due to their high volumetric capacity and safety aspect. Generally, a crystal layer of gas hydrate is preferentially created on the surface of an aqueous phase which results in both low hydrate conversion and slow reaction without mechanical agitations. This study introduces CP hydrate seeds at very small quantities to accelerate the nucleation and growth of the CH4 hydrate with SDS. To choose the appropriate amount of CP in the system for massive sI CH4 hydrate formation, several hydrate slurries with various amounts of CP were characterized by powder X-ray diffraction and Raman spectroscopy. Additionally, from the visual observations of the hydrate growth behavior, the direction of hydrate crystallization significantly affected the hydrate growth and conversion rate. With the highest degree of sub cooling, the volumetric storage efficiency reached 90% of the theoretical values in 50 min with no induction period, and this promotion effect was also confirmed in an expanded reactor system. Thus, sill CP hydrate seeds result in a dramatic improvement in the sI CH4 hydrate formation rate and high volumetric storage capacity. (C) 2017 Elsevier Ltd. All rights reserved.</P>
A Linear InGaP/GaAs HBT Power Amplifier Using Parallel-Combined Transistors With IMD3 Cancellation
Baek, Seungjun,Ahn, Hyunjin,Nam, Ilku,Ryu, Namsik,Lee, Hui Dong,Park, Bonghyuk,Lee, Ockgoo THE INSTITUTE OF ELECTRICAL ENGINEERS 2016 IEEE Microwave and Wireless Components Letters Vol. No.
<P>In this letter, we present a linear InGaP/GaAs HBT power amplifier (PA) with parallel-combined transistors for small-cell applications. Ballast resistors with bypass resistors and capacitors are employed in parallel-combined transistors. When the resistors and capacitors are set to appropriate values, IMD3 components of the parallel-combined transistors are found to be out of phase with each other by 180. and are canceled out at the output. The experimental results show that the proposed HBT PA with parallel-combined transistors produces a saturated output power of 33.5 dBm at 0.88 GHz, with a power-added efficiency (PAE) of 46.1% at a 5-V supply voltage. To validate the effectiveness of the proposed HBT PA for linearity improvement, the implemented PA is also tested with a long-term evolution (LTE) signal (8.1-dB PAPR with 10-MHz bandwidth). The proposed PA achieves an adjacent channel leakage ratio (ACLR) below -45 dBc at an average power of 25.6 dBm with a PAE of 18.8% without applying predistortion.</P>
백승준(Seungjun Baek),전용진(Yongjin Jeon),김한기(Hangi Kim),김종성(Jongsung Kim) 한국정보보호학회 2020 情報保護學會誌 Vol.30 No.3
최근 사물인터넷 환경이 발달하면서 센서 네트워크, 헬스케어, 분산 제어 시스템, 가상 물리 시스템 등의 다양한 분야의 산업이 부상하고 있다. 이를 위한 소형 컴퓨팅 기기가 보편화되고 있지만, 해당 기기들은 제한된 리소스라는 공통의 약점을 가지고 있다. 제한된 환경에서 중요한 데이터들을 보호하기 위해서는 많은 리소스가 필요한 기존의 암호 알고리즘보다 적은 리소스로도 운용할 수 있는 경량암호 알고리즘이 필요하다. NIST에서는 2015년부터 제한된 환경에 적합한 경량암호 알고리즘을 표준화하기 위한 공모사업을 진행 중이다. 현재 2라운드 과정을 거치고 있으며 총 32종의 알고리즘에 대한 안전성, 효율성 분석이 이루어지고 있다. 이에 본 논문에서는 NIST 경량암호 공모사업 1, 2라운드 후보 알고리즘들을 특징별로 분석하고, 몇 가지 알고리즘들을 심층적으로 살펴본다. 또한 향후 전망과 계속 진행될 공모사업의 타임라인을 제시한다.
서핑가능 지역의 지속가능한 서핑을 위한 서핑자원 관리 - 강원도 양양군 죽도해변을 중심으로
백승준(Seungjun Baek),박용성(Yong Sung Park) 한국해안해양공학회 2020 한국해안해양공학회 논문집 Vol.32 No.6
서핑은 자연적으로 발생하는 파도를 이용하는 스포츠로 자연환경의 변화에 민감하게 작용한다. 다시 말해서, 서핑을 할 수 있는 파도가 도달하던 해안에서 인근의 해안시설물의 건설이나 해안 침식, 표사이동에 의한 해안선의 변화와 같은 요인이 파도를 서핑에 부적합한 방향으로 변하게 만들 수 있다. 본 연구에서는 서핑에 적합한 파도가 형성되는 데에 영향을 주는 해안환경 특성들을 일컬어 서핑자원(Surfing Resources)이라 하고, 이를 해안공학적 방법론으로 분석하였다. 그리고 Delft3D-WAVE 모듈(SWAN model)을 활용한 강원도 양양군 죽도해변의 서핑자원 분석을 통해, 서핑 파도의 지속가능성을 평가하는 방법에 대해 제시하였다. Surfing is a sport sensitive to changes in the natural environment, using naturally occurring waves. In other words, factors such as the construction of coastal structures, coastal erosion, and sediment transportation could cause the wave to change into a direction inappropriate for surfing at the shore where surfable waves were reaching. In this study, we call the characteristics of the coastal environment that affect the formation of surfable waves as surfing resources, which is subsequently analyzed by coastal engineering methodologies. Also, using Delft3D-WAVE module (SWAN model), a way to evaluate sustainability of surfable wave is suggested through analysis of surfing resources at Jukdo, Yangyang, Gangwon Province, Republic of Korea.