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다중경로 채널환경에서 수신 다이버시티를 이용하는 2PAM-TH-UWB 시스템의 오류 성능 분석
백선영(Sunyoung Baek),강윤정(Yunjeong Kang),김상준(Sangchoon Kim) 대한전기학회 2008 대한전기학회 학술대회 논문집 Vol.2008 No.10
본 논문애시는 다중경로가 무수히 많은 환경에서 다중안테나를 이용하여 고속의 데이터 전송률을 달성하기 위한 초광대역(UWB Ultra-Wideband) 시스템의 성능 향상에 대해 연구한다. 다중 수신안테나가 제공하는 공간다이버시티와 RAKE 수신기가 제공하는 시간 다이버시티가 2PAM(Binary Pulse Amplitude Modulation) TH(Time Hopping) UWB 통신 시스템의 성능에 미치는 영향을 분석한다. 시뮬레이션 경과를 통해 다중 수신안테나의 수가 증가함에 따라 TH-UWB 시스템의 BER(Bit Error Rate) 성능이 크게 향상됨을 보인다. 또한 SRAKE(Selective RAKE)에 의해 선택되는 다중경로 성분의 수가 증가할수록 시스템의 성능이 더욱 향상됨을 확인한다.
부탄 개질기 운전조건에 따른 SOFC 시스템 효율에 대한 연구
김선영(Sunyoung Kim),백승환(Seungwhan Baek),배규종(Gyujong Bae),배중면(Joongmyeon Bae) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.4
본 연구에서는 부탄 개질기 운전조건에 따른 SOFC 시스템 효율을 모델링을 통해 분석하였다. SOFC 시스템은 크게 개질기, SOFC, 폐열 회수 장치로 구성하였다. 탄화수소 개질 반응으로 선택한 수증기 개질 반응은 흡열반응인 데에 반해 SOFC 에서 일어나는 전기화학반응은 발열반응이다. 따라서 시스템의 열관리 방법에 따라 효율이 크게 달라진다. 세부적으로 수증기 개질 반응은 운전 온도에 따라 수증기 개질 반응과 예개질 반응으로 분류되는데, 해석 결과 예개질 반응을 적용한 SOFC 시스템의 경우 더 높은 효율을 나타내었다. 시스템의 효율은 SOFC 온도 유지를 위한 열량과 온수로 회수되는 열량에 따라 달라지는데, 예개질 반응을 적용할 경우, 열관리가 더욱 효율적이어서 높은 효율을 나타내는 것으로 분석되었다. In this study, the efficiency of a solid-oxide fuel cell (SOFC) system with a steam reformer or prereformer was analyzed under various conditions. The main components of the system are the reformer, SOFC, and water boiling heat recovery system. Endothermic and exothermic reactions occur in the reformer and SOFC, respectively. Hence, the thermal management of the SOFC system greatly influences the SOFC system efficiency. First, the efficiencies of SOFC systems with a steam reformer and a prereformer are compared. The system with the prereformer was more efficient than the one with steam reformer due to less heat loss. Second, the system efficiencies under various prereformer operating conditions were analyzed. The system efficiency was a function of the heat requirement of the system. The efficiency increased with an increase in the operating temperature of the prereformer, and the maximum system efficiency was observed at 450°C for a S/C of 2.0.
Effects of Hormone Replacement Therapy on Bone Mineral Density in Korean Adults With Turner Syndrome
Kim SunYoung,Kim Heeyon,Lee Inha,Choi Euna,Baek JinKyung,Lee Jaekyung,Kim Hae-Rim,Yun Bo Hyon,Choi Young Sik,Seo Seok Kyo 대한의학회 2024 Journal of Korean medical science Vol.39 No.1
Background: Turner syndrome (TS) is a common chromosomal abnormality, which is caused by loss of all or part of one X chromosome. Hormone replacement therapy in TS is important in terms of puberty, growth and prevention of osteoporosis however, such a study has never been conducted in Korea. Therefore, the purpose of our study was to determine relationship between the starting age, duration of estrogen replacement therapy (ERT) in TS and develop a hormone replacement protocol suitable for the situation in Korea. Methods: This is retrospective study analyzed the medical records in TS patients treated at the Severance hospital, Yonsei University College of Medicine, Seoul, Korea from 1997 to 2019. Total of 188 subjects who had received a bone density test at least once were included in the study. Korean National Health and Nutrition Examination Survey (KNHANES) was used for achieving bone mineral density (BMD) of normal control group. Student’s t-test, MannWhitney U test, ANOVA and correlation analysis were performed using SPSS 18.0. Results: Each BMD measurement was significantly lower in women with TS than in healthy Korean women. Early start and longer duration of ERT is associated with higher lumbar spine BMD but not femur neck BMD. Femur neck BMD, but not lumbar spine BMD was significantly higher in women with mosaicism than 45XO group. Conclusion: Early onset and appropriate duration of hormone replacement therapy is important for increasing bone mineral density in patients with Turner syndrome. Also, ERT affects differently to TS patients according to mosaicism.
가상 발전소의 기능적 특징을 고려한 사용자 중심 LDS 인터페이스 디자인
안선영(Sunyoung Ahn),하태현(Taehyun Ha),김상연(Sangyeon Kim),백승엽(Seungyup Baek),조영혁(Younghyeok Cho),최원용(Won-Yong Choi),이상원(Sangwon Lee) 대한인간공학회 2019 大韓人間工學會誌 Vol.38 No.1
Objective: This study proposes a user interface design guideline for large display systems (LDSs) in virtual power plants (VPPs) to support the effective management of power resources. Background: VPP is a technology which enables to manage unstable distributed power resources effectively. To achieve efficient management, a proper user interface needs to be suggested considering the technical aspects of VPP. Method: Based on a technical specification of VPP, we draw a hierarchical information architecture for VPP operations and suggest proper ways of the information visualization and color application for user interface design. Results: We present an example of interface design for LDS in VPP with some general design guidelines. Conclusion: To develop a proper interface of LDS in VPP, designers need to 1) identify an information architecture for VPP operations, 2) place functional modules in LDS considering hierarchical properties of the information architecture, and 3) visualize the modules focusing on the brightness and conventional rules of design. Application: The results of this study can be applied to construct a user interface system of VPP.