태양광 발전 시스템용 고효율 마이크로컨버터 토폴로지에 관한 연구

강건일(Geon-Il Kang),서동수(Dong-Soo Seo),최연옥(Youn-Ok Choi) 한국산업기술융합학회(구. 산업기술교육훈련학회) 2024 산업기술연구논문지 (JITR) Vol.29 No.1

본 논문에서는 태양광 발전시스템에 사용되는 마이크로 컨버터의 특성을 분석하였다. 마이크로 컨버터는 태양광패널에 하나씩 부착되며, 각 패널의 발전 성능을 최적화하는 역할을 한다. 이는 태양광 발전시스템의 성능을 최적화 하는 것을 의미한다. 마이크로 컨버터가 적용된 태양광 발전시스템의 경우 중앙 집중식 MPPT 제어와 분산형 MPPT 제어를 혼합하여 사용한다. 음영으로 인한 미스매칭시 중앙집중식 MPPT 제어만으로 발생하는 MPPT 손실을 개선하기 위해 분산형 MPPT 제어를 동시에 수행한다. 그리고 미스매칭이 없는 경우는 중앙집중식 MPPT 제어만 동작하고 마이크로 컨버터는 MPPT 제어가 아닌 바이패스 제어로 동작한다. 또한 본 논문은 벅 컨버터 토폴로지의 바이패스 운전 모드에서의 손실을 분석하여 고효율 바이패스 토폴로지를 제안하였다. 그리고 프로토타입을 제작 하여 성능을 비교 분석하여 제안한 토폴로지를 검증하였다. In this study, we analyze the characteristics of microconverters utilized in photovoltaic systems. Microconverters are individually attached to solar panels and are instrumental in optimizing the power-generation performance of each panel, thereby enhancing the overall efficiency of photovoltaic systems. The utilization of microconverters implies the need for optimizing the performance of the entire photovoltaic system. In systems employing microconverters for photovoltaic power generation, a combination of centralized and distributed maximum power point tracking (MPPT) controls is employed. Distributed MPPT control operates concurrently to mitigate MPPT losses incurred solely by centralized MPPT control during mismatching due to shading. In the absence of a mismatch, only centralized MPPT control is engaged, and the microconverter operates using bypass control instead of MPPT control. In addition, this study proposes a high-efficiency bypass topology by scrutinizing the losses in the bypass operation mode of the buck converter topology. A prototype was manufactured to facilitate a comparison and analysis of the performance of the proposed topology.

태양광 발전 시스템용 고효율 파워옵티마이저 토폴로지에 관한 연구

강건일(Geon-Il Kang),최연옥(Youn-Ok Choi),서동수(Dong-Soo Seo) 대한전기학회 2022 대한전기학회 학술대회 논문집 Vol.2022 No.7

디지털 제어기를 이용한 Flyback converter 관한 연구

강건일(Kang Geon Il),이정운(Lee Jeong Woon),양승학(Yang Seung Hak),임영철(Lim Young Cheol) 전력전자학회 2008 전력전자학술대회 논문집 Vol.- No.-

컨버터의 제어는 보통 아날로그 제어기를 기반으로 한다. 전용 아날로그 상용 IC들로 복잡한 회로의 장점을 극복하고 있고 이로 인해 기본성능을 수행하고 저가격화와 사용상의 편의를 얻을 수 있다. 그러나 이러한 장점은 디지털 제어기의 성능개선과 가격의 하락으로 전용의 IC에 필적하는 파워 컨버터의 응용을 가능하게 만들었다. DC-DC 컨버터 내부 파라미터에 대한 모니터링이 가능하며, 아날로그 제어방식에서는 처음의 사양에 의해 고정된 출력전압을 얻었지만 디지털 제어 방식에서는 PC와 DC-DC 컨버터간 통신을 통하여 사용자가 원하는 임의의 전압을 얻어낼 수 있고 원격제어가 가능하다. 본 논문에서는 이와 같은 디지털 제어기의 장점과 실용성을 제시하고자 소신호 모델식을 기반으로 하여 디지털 모드 제어기를 설계하고, 이를 구현하기 위해 원칩 마이크로컨트롤러인 microchip사의 dsPIC30F2020을 사용하였다. 마이크로컨트롤러를 이용한 DC-DC 컨버터의 실용성을 검토하였다.

분광계를 이용한 당 농도 측정방법 연구

강건호(Geon-Ho Kang),임정묘(Jeong-Myo Im),민경은(Kyoung-Eun Min),장은석(Eun-Seok Jang),김민성(Min-Sung Kim),설수현(Su-Hyeon Seol),전재훈(Jae-Hoon Jun) 대한전기학회 2020 대한전기학회 학술대회 논문집 Vol.2020 No.7

Thermocycling이 금속과 레진시멘트간의 결합강도에 미치는 영향

강건구,정관호,최정호,안승근,송광엽,박찬운,Kang, Geon-Gu,Chung, Kwan-Ho,Choi, Jeong-Ho,Ahn, Seung-Geun,Song, Kwang-Yeob,Park, Chan-Woon 대한치과보철학회 1996 대한치과보철학회지 Vol.34 No.2

The purpose of this study was to evaluate the effect of thermocycling on bond strength between metal and resin cement according to thermocycling, and to observe the bond failure modes with optical microscope(X30). For this purpose, Super-Bond C & B and Panavia 21 resin cement were used. Metal specimens were made of Vera-Bond and the surface of specimens were sandblasted with $50{\mu}m$ aluminum oxide. All experimental groups were stored in $37^{\circ}C$ distilled water for 72 hours, followed by thermocycling between $5^{\circ}C$ and $55^{\circ}C$ with 15 second dwell time. 500, 1000, 2000 cycles of thermocycling were executed and the tensile bond strength was measured by Instron Universal Testing Machine(Model 4201) The obtained results were as follows : 1. Super-Bond C & B and Panavia 21 did not show statistically significant difference accor-ding to thermocycling test(P>0.05). 2. Super-Bond C & B specimens exhibited statistically significant higher tensile bond stre-ngth than Panavia 21 for all experimental groups(P<0.05). 3. Super-Bond C & B exhibited mixed mode failure with partial adhesive and partial cohe-sive failure, and most of Panavia 21 exhibited cohesive failure and some mixed mode failure.

도시숲과 가로수가 대기 흐름과 기온에 미치는 영향에 관한 수치 연구

강건,최원식,김재진,Kang, Geon,Choi, Wonsik,Kim, Jae-Jin 대한원격탐사학회 2022 대한원격탐사학회지 Vol.38 No.6

This study investigated the effects of the urban forest and street trees on flow and temperature distribution in the Daegu National Debt Redemption Movement Memorial Park. For this, we implemented tree-drag and tree-cooling parameterization schemes in a computational fluid dynamics (CFD) model and validated the simulated wind speeds, wind directions, and air temperatures against the measured ones. We used the wind speeds, wind directions, air temperatures predicted by the local data assimilation and prediction system (LDAPS) as the inflow boundary conditions. To investigate the flow and thermal characteristics in the presence of trees in the target area, we conducted numerical experiments in the absence and presence of trees. In the absence of trees, strong winds and monotonous flows were formed inside the park, because there were no obstacles inducing friction. The temperature was inversely proportional to the wind speed. In the presence of trees, the wind speeds(temperatures) were reduced by more than 40 (5)% inside the park with a high planting density due to the tree drag (cooling) effect, and those also affected the wind speeds and temperatures outside the park. Even near the roadside, the wind speeds and temperatures were generally reduced by the trees, but the wind speeds and air temperatures increased partly due to the change in the flow pattern caused by tree drag.

건물 밀집 지역에서 대기오염물질 분포에 미치는 건물과 지형의 영향에 관한 수치 연구

강건,김재진,이재범,Kang, Geon,Kim, Jae-Jin,Lee, Jae-Bum 대한원격탐사학회 2020 대한원격탐사학회지 Vol.36 No.2

Using a computationalfluid dynamics(CFD) model, thisstudy evaluated the representativeness of an air quality monitoring system (AQMS) in an urban area and presented a methodology to determine the suitable AQMS locations for specific purposes. For this, we selected a 1.6 km × 1.6 km area around the Eunpyeong-gu AQMS (AQMS 111181) as a target area. We conducted simulationsfor two emission scenarios (scenario one: air pollutants transported from inflow boundaries, scenario two: air pollutants emitted from roads). Urban airflows were markedly influenced by mountainous terrain located in the northeast and southeast of the target area, and complicated airflow patterns occurred around the buildings. The distributions of air pollutants were dependent on the terrain (mountain) in scenario one, but the road location and building height in scenario 2. We evaluated whether the AQMS could represent the air quality in the target area based on the simulations for two scenarios. The concentrations simulated at the AQMS were similar in magnitude to the layer mean concentrations, which indicated good representativeness for the air quality in the target area. We also suggested which locations were suitable for different measurement purposes (hot spots, clean zones, average zones, shelter zones, equi-background zones).

디지털 카메라용 줌렌즈에서 대칭성 오차요인에 의한 상면 변화의 보정과 이에 따른 불량률 예측

류재명,강건모,이해진,이혁기,조재흥,Ryu, Jae-Myung,Kang, Geon-Mo,Lee, Hae-Jin,Lee, Hyuck-Ki,Jo, Jae-Heung 한국광학회 2006 한국광학회지 Vol.17 No.5

In the zoom lens of digital still cameras with the variation of the image plane generated by various symmetric error factors such as curvature, thickness and refractive index error of each lens surface about the optic axis, we induce a theoretical condition to fix constantly the image plane by translating the compensator group of the zoom lens by using the Gaussian bracket. We confirm the validity of this condition by using three examples of general zoom lens types with 3, 4, and 5 groups, respectively. When these error factors are randomly changed within the range of tolerance according to the Monte Carlo method, we verify that the distributions of the degree of moving of the compensator are normal distributions at three zoom lens types. From capability analysis using these results, we theoretically propose the method estimating the standard deviation, that is, sigma-level, as a function of the maximum movement of the compensator.

반도체 와이어 본딩 검사용 다중배치 현미경 광학계에 대한 공차분석

류재명,이해진,강건모,정진호,백승선,조재흥,Ryu, Jae-Myung,Kim, Jae-Bum,Kang, Geon-Mo,Jung, Jin-Ho,Baek, Seung-Sun,Jo, Jae-Heung 한국광학회 2006 한국광학회지 Vol.17 No.2

가우스 괄호법을 이용한 굴절능 배치 방법과 등가렌즈 설계법으로 기존에 설계한 반도체와이어 본딩 검사용 다중배치 현미경 광학계에 대한 공차 분석을 하였다. 축상 대칭 공차인 곡률과 두께에 대한 공차는 회절 한계에 의한 초점심도 내에서 후방초점거리(BFL)가 변하도록 결정하였고, 축 비대칭 공차인 decenter와 tilt에 대한 공차는 0.7 field에서 공간주파수 50 lp/mm에서의 MTF(Modulation Transfer Function) 변화가 5% 이내가 되도록 시행착오 방법으로 정하였다. 이 결과 공차분포확률에 관계없이 MTF의 감소율이 5% 미만 되는 곳에 가장 많은 확률로 공차가 분포하므로 위와 같은 방법으로 공차를 부여하면 원하는 본 광학계의 결상 성능을 만족시킬 수 있음을 확인하였다.

비대칭 오차요인이 있는 편심 광학계에서의 종수차 계산

류재명,조재흥,강건모,이해진,요네야마 슈지,Ryu, Jae-Myung,Jo, Jae-Heung,Kang, Geon-Mo,Lee, Hae-Jin,Yoneyama, Suji 한국광학회 2010 한국광학회지 Vol.21 No.4

When the optical image stabilization is implemented by moving one of the lens groups in a zoom system, decentration should be considered in the optical design process. Although it is partially possible to calibrate optical performances in an optical system with non-symmetrical elements by using a lot of commercial software, the results of calibrating longitudinal aberrations have some calibration errors because of the lack of precise consideration of decentered optical systems. In particular, the amount of distortion in paraxial ray tracing is different from the experimental value because paraxial ray tracing in the optical system is not useful. In this paper, in order to solve this problem being from various commercial lens design software, the set of equations of paraxial ray tracing in a zoom lens system with the non-symmetrical elements like decentration or tilt are theoretically induced. Then, the methods to calibrate the equations of longitudinal aberrations by using these equations in a non-symmetrical optical system are presented. The method of calibrating longitudinal aberrations can in practice be used to correct hand shaking effects in a zoom lens system.