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유형렬,최종민 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
Colloidal quantum dots (CQDs) have been considered as promising materials for solar cells because of their size-dependent characteristics tunability, solution processability and potential of multiple exciton generation. The architecture of CQD photovoltaics relies on a planar heterojunction consisting of CQD light harvesting layer and charge collection layers, and the band alignment engineering of these layers is crucial for efficient charge collection. Here, we introduce a novel interfacial layer for CQD photovoltaics leading improved charge collection ability and power conversion efficiency.
유형렬,최종민,You, Hyung Ryul,Choi, Jongmin 한국전기화학회 2019 한국전기화학회지 Vol.22 No.3
Metal halide perovskite materials are considered as promising semiconducting materials for next-generation solar cells due to their unique electrical and optical properties. Intensive progress in perovskite solar cell yielded a certified power conversion efficiency over 24%. However, most of highly efficient perovskite solar cells required Pb-based perovskite materials, which is a critical obstacle for their commercialization, and development of Pb-free perovskite materials is one of recent urgent issues in this field. In this paper, we will introduce recent research progress on Pb-free perovskite solar cells. 금속 할로겐 페로브스카이트 (perovskite)는 우수한 전기적, 광학적 특성으로 인해 차세대 태양전지의 핵심 소재로 큰 주목을 받고 있다. 페로브스카이트 태양전지는 등장 이후 전례 없는 단기간 효율 향상을 보이며 현재 24% 이상의 인증된 광전 변환 효율을 달성하였지만, 대부분의 고성능 페로브스카이트 태양전지는 유독성 납 (Pb)을 기반으로 한 페로브스카이트를 사용한 것으로, 향후 상용화를 위해서는 납을 쓰지 않는 친환경 페로브스카이트 개발이 필수적이다. 본 글에서는 비납 페로브스카이트 물질 및 연구 동향에 대해서 소개하고자 한다.
DDS를 이용한 FFH/BFSK 시스템 송신부의 주파수합성기 설계 및 성능평가
유형렬,조형래,정지원,이두석,김기문 韓國海洋大學校電波通信硏究所 1999 電波通信硏究所論文集 Vol.1 No.-
이동 통신의 세계적 흐름은 디지털화, 고속화 그리고 대용량화의 추세로 나아가고 있다. 또한 한정된 주파수 자원을 효율적으로 이용하기 위하여 대역확산 방식이 그 주를 이루고 있다. 본 연구에서는 고속 주파수도약 방식을 이용하였다. 잡음 등의 여러 가지 문제점을 가지고 있는 PLL(Phase Lock Loop) 대신, PLL의 단점을 최소화할 수 있는 디지털 소자인 직접 디지털 주파수합성기(DDS : Direct Digital Synthesizer)를 사용하여 FFH 시스템 송신부의 주파수합성기를 설계하였다. PLL를 이용하여 고속 주파수 도약시스템을 설계하는 경우, PLL의 settling time의 설정과 요구되는 RF대역폭 등의 설계사양을 만족시키기가 어려우며 평형변조기 사용에 의한 회로의 복잡성으로 인한 제약이 따르게 된다. 본 연구에서는 DDS를 이용하여 고속 주파수도약 시스템을 설계하기 위한 성능평가에 대하여 연구하였으며, 오율 개선의 해석과 도약율 1 Mhps, 5 ㎒ RF 대역쪽의 고속 주파수 도약이 가능한 시스템을 설계하고 성능을 평가하였다. The global trends of mobile communication system is moving toward digitizing high-speed and large-capacity. Also, to utilize the limited frequency-resource efficiently, spread spectrum system is a mainstream. In this study we are concerning with the fast frequency-hopping system. Instead of the PLL with many problems such as phase-noise, we used the DDS is popular in these days minimizes the disadvantage of PLL. In the case the FFH system is designed using the PLL, it is difficult to satisfied of the design conditions such as RF badwidth and the settling time of PLL, and it has limitation because of complex circuit by using the balanced modulator. In this study, we evaluated the performance in order to design the FFH system using the DDS. The sys tem that has the improvement of error rate, 1 Mhps hopping rate and 5 ㎒ RF bandwidth is designed and evaluated.
인삼Saponin이 주정성 간손상에 미치는 영향에 관한 실험적 연구
유형렬,김종만,구국회 한양대학교 의과대학 1982 한양의대 학술지 Vol.2 No.2
Alcoholic lever disease, the occurrence of which has been highly increased includes spectrum of cloudy swelling, steatosis, fibrosis and cirrhosis. However it is indicated that relevent teatments on this disease are still symtomatic and conservative. This study was conducted anatopathologically and biochemically to evaluate the protective effect of ginseng saponin upon alcoholic liver damage. 240 healthy sprague-Dawley rats weighing about 200gm were used for this experiment and divided into the following 8 groups: 1. Control group fed basic diet. 2. Alcohol administered group. 1) low-concentrated alcohol administered group given 25% alcohol 2) mid-concentrated alcohol administered gorup given 32.5% alcohol 3) high-concentrated alcohol administered gorup given 40% alcohol 3. Alcohol and ginseng saponin administered groups. 1) low-concentrated alcohol and saponin administered group given 25% alcohol and ginseng saponin 2) mid-concentrated alcohol and saponin administered group given 32.5% alcohol and ginseng saponin 3) high-concentrated alcohol and saponin administered group given 40% alcohol and ginseng saponin 4. Ginseng saponin administered group. The basic diet was nutritionally composed of adequate soild diet, and each rat was administered orally 20-25gm of basic diet per day. Control group was administered basic diet with approximately 20ml of alcohol, instead of water, in addition to basic diet. Ginseng saponin was administered orally 5mg per rat per day with normal saaline. The results obtained from this study were as follows: 1. In alcohol administered group, serum enzyme (GOT, GPT, alkaline phosphatase) and bilirubin levels were elevated. Various degrees of cellular swelling, congestion and bile pigmentation were observed. Fatty degeneration and thickening of venular wall were also noter in mid- and high-concentrated groups at 40 days. 2. In alcohol and ginseng saponin administered group, serum enzyme (GOT, GPT, alkaline phosphatase) and bilirubin levels were decreased than that of alcohol administered group. Various histologic changes such as cellular swelling, congestion, bile pigmentation, fatty degeneration, and thickening of venular wall were markedly subsided than that of alxohol administered group. The data obtained from this experiment indicated that ginseng saponin reduced histopathologic changes caused by alcohol as well as lowered abnormally elevated blood enzyme (GOT,GPT, alkaline phosphatase) and direct bilirubin levels.
김영오,유형렬,이재형,기노석,황인담,Kim, Young-Oh,Yoo, Hyung-Yul,Lee, Jae-Hyung,Ki, No-Suk,Hwang, In-Dam 대한예방의학회 1988 Journal of Preventive Medicine and Public Health Vol.21 No.2
This study was carried out to investigate the heavy metal contents and their correlationship between paddy soil and brown rice near the Kum-River area. In this study, eighty soil samples and forty brown rice samples were taken from the paddy soil. The contents of heavy metals were measured by flame atomic absorption spectrophotometry. The results were as follows: 1. The average contents of soluble heavy metals in surface soil were Cd 0.19, Cu 15.31, Zn 18.10 and Pb 9.08 ppm. The average contents of soluble heavy metals in subsurface soil were Cd 0.19, Cu 14.52, Zn 17.75 and Pb 8.11 ppm. There was no statistically significant difference between the two layers. 2. The contens of Cu, Zn and Pb of Taejeon(S6) and Cd of Sinbyung(S5) in surface soil were higher than those of other areas. The contents of Cd and Cu of Taejeon(S6) and Zn and Pb of Kumnam(S3) in brown rice were higher than those of other areas and four heavy metals in soil and brown rice of Simchon(S7) were lower than those of other areas. 3. The ratio of soluble contents(Cd:Cu:Zn:Pb) in surface soil was 1:79:93:47, that of soluble contents in subsurface soil was 1:76:94:43, and that of total contents in brown rice was 1:84:294:12. 4. The correlationship of the content between soluble heavy metals in surface(0-15 cm depth) soil total heavy metals in brown rice was found to be order of Cd>Cu>Zn>Pb. The correlationship of the content between soluble heavy metals in subsurface(20-30 cm depth) soil and total heavy metals in brownricewasfoundtobeorderofcu>Cd>Zn>Pb.