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레이더경보수신기용 CD대역 진폭비교 방향탐지 정확도 측정 시스템 개발
현예지,최남우,최혁재,조원택,김성훈 대한전자공학회 2022 전자공학회논문지 Vol.59 No.11
Radar Warning Receiver(RWR) is Electronic Warfare Support equipment, which detects and measures threat radar signal in high speed then provides real time warning. This paper describes the development of an amplitude comparison direction finding accuracy measuring system for CD band RWR, which is intended to be loaded on aircraft for the first time in Korea. The developed RWR equipment receives CD band signal from Blade Antenna, executes signal processing in RF and Digital module, and derives angle of arrival(AOA) using the amplitude comparison direction finding logic. Since CD band blade antenna has an unbalanced beam pattern, unlike EJ band or spiral antenna, this paper measures direction finding accuracy by adding a beam calibration algorithm. As a result of conducting a radiation test on the CD band in the anechoic chamber to verify the direction finding accuracy, the performance is confirmed that the average CD band direction finding accuracy is measured by 6.73% higher than the target performance of OO degree RMS in 360 degree azimuth and 45 degree elevation range.
현예지,김주경,김민정,정성근,김지연 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.2
This research aimed to evaluate the potentialinhibitory effect of mineral-rich Jeju lava sea water(JLSW) on lipid accumulation. This study optimized thecalcium (Ca): magnesium (Mg) ratio (5:1, 2.5:1, 1:1) ofJLSW and evaluated the effect on lipid accumulation in3T3-L1 cells using Oil Red O staining. JLSW with a highCa:Mg ratio (5:1) suppressed lipid accumulation in 3T3-L1adipocytes. Based on these in-vitro results, the effects ofJLSW on lipid accumulation were investigated in C57BL/6 J mice fed high-fat diets for 14 weeks. Epididymal adiposetissue weight was significantly decreased in mice thatreceived JLSW with a hardness of 800 or 100 mg/Lcompared to HFD. Adipocyte size was significantlyreduced in mice treated with JLSW with a hardness of20 mg/L in comparison with HFD. Thus, long-term intakeof JLSW may be expected to have anti-obesity effects dueto the reduction of lipid accumulation.
현예지,박수연,김지연 한국식품과학회 2023 Food Science and Biotechnology Vol.32 No.3
This study aimed to evaluate the effect of fermented rice germ extracts on the inhibition of glucose uptake in the gastrointestinal (GI) tract. Samples were prepared by extracting rice germ fermented with Lactobacillus plantarum with 30% ethanol (RG_30E) or 50% ethanol (RG_50E). Ferulic acid was determined as the active component in the samples. RG_30E significantly inhibited glucose uptake and mRNA expression of GLUT2 and SGLT1 to a larger extent than RG_50E in Caco-2 cells. A single oral administration was performed on C57BL/6 mice to confirm which substrate (glucose, sucrose, or maltose) the sample inhibited absorption of, improving postprandial blood glucose elevation. As a result, RG_30E resulted in significantly lower blood glucose levels and AUC after glucose and sucrose administration. Therefore, fermented rice germ extracted with 30% ethanol regulates glucose uptake through glucose transporters and can be expected to alleviate postprandial hyperglycemia in the GI tract.
PFC 컨버터용 부스트 인덕터 파레토 최적화 방안 연구
현예지(Ye-Ji Hyeon),이동인(Dong-In Lee),정성욱(Seong-Wook Jeong),김원준(Won-Jun Kim),이상윤(Sang-Yun Lee),장근호(Geun-Ho Jang),최현준(Hyun-Jun Choi),윤한신(Han-Shin Youn) 전력전자학회 2023 전력전자학회 논문지 Vol.28 No.5
This paper proposed an inductor optimal design algorithm in terms of volume and loss when designing a boost inductor for PFC. Inductors occupy a large volume in the converter, and reducing the volume of the inductor is necessary to improve power density. However, a smaller volume corresponds to a greater maximum flux density, thereby leading to higher losses. The Pareto optimization technique was applied to design an inductor optimized for volume and loss, which show a trade-off relationship. This paper also proposed an algorithm for efficiently generating a Pareto set of volume and loss optimization problems of inductors. This algorithm was applied to the boost inductor of the interleaved totem-pole bridgeless PFC converter, and its effectiveness was verified through experiments.
수소 연료 전지 기반 철도 차량용 3-Level Boost 컨버터의 EMI 필터 회로 연구
이동인,현예지,정성욱,김민재,윤한신 한국철도학회 2023 한국철도학회논문집 Vol.26 No.7
Recently, the development of power and driving system technology for railway vehicles has steadily adopted hydrogen fuel cells with the goal of reducing carbon emissions and developing eco-friendly technologies. DC/DC converters are used to boost the low level voltage of fuel cells to the high level above 1,000 V required by an inverter and battery system; a 3-Level Boost converter is a suitable alternative. However, since the 3-Level Boost converter generates common mode EMI noise due to the switching operation, countermeasures are needed. Generally, Y capacitors or conventional EMI filter circuits are applied as a countermeasure to the common mode EMI noise problem, but this is not a suitable for 3-Level Boost converters, so a different EMI filter circuit is needed. In this paper, the necessity of an EMI filter and a new EMI filter structure based on a 3-Level Boost converter is presented and system validity is verified by simulation results.
다수의 Photovoltaic Submodule용 컨버터를 통합한 DPP 컨버터
임지훈,이동인,현예지,최재혁,윤한신 전력전자학회 2022 전력전자학회 논문지 Vol.27 No.1
Recently, photovoltaic (PV) systems have been gradually applied in eco-friendly vehicle applications to improve fuel economy. The relevant market is expected to continue to grow because the installation of large-capacity PV systems to other eco-friendly vehicles, such as electric buses and trains, is being considered. However, in a PV system, power imbalance between submodules and low power generation efficiency occur due to factors such as cell aging, contamination, and shading. To resolve this problem, various differential power processing (DPP) converters have been researched and developed. However, conventional DPP converters suffer from large volume and low efficiency. Therefore, to apply DPP converters to eco-friendly vehicles, increasing efficiency and reducing volume and price compared with existing DPP converters is necessary. In this paper, a novel DPP converter with an integrated transformer is proposed and analyzed. The proposed DPP converter uses a single magnetic component by integrating transformers and secondary sides of conventional DPP converters. Therefore, the proposed DPP converter shows high power density and high efficiency, and it is suitable for PV systems in eco-friendly vehicle applications.