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Polymer Solar Cells with Ternary Blend Nanolayers
Kim, Youngkyoo,Shin, Minjung,Kim, Hwajeong American Scientific Publishers 2008 Journal of Nanoscience and Nanotechnology Vol.8 No.12
<P>We report polymer solar cells with a polymer blend nanolayer (film) that consists of two electron-donating polymers and one electron-accepting polymer. Regioregular poly(3-hexylthiophene) (P3HT) and poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene] (MDMO-PPV) were employed as electron-donating polymers, whilst poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) was used as an electron-accepting polymer. Two kinds of solvent and film thickness were applied to examine their effect on the device characteristics. Results showed that the device performance was better when <I>p</I>-xylene was used as a solvent, whilst thicker blend films exhibited better power conversion efficiency. A nanohole morphology found in the blend film made using chlorobenzene, compared to the blend film made using <I>p</I>-xylene, was assumed to be responsible for the relatively poor device performance in spite of higher absorption in the longer wavelengths. Still low efficiency of present devices was attributed to the existence of charge blocking resistances in the bulk polymer nanolayer.</P>
김영규(Youngkyoo Kim),소아람(Aram So),양태연(Taeyeun Yang),김정훈(Junghoon Kim) 한국정보과학회 2007 한국정보과학회 학술발표논문집 Vol.34 No.1C
본 논문에서는 현대 사회의 취미 생활로 깊이 자리 잡은 실용음악 악기 중 하나인 베이스 기타의 효과적인 학습을 위한 새로운 기반 시스템을 제안한다. 현대인들은 바쁜 시간에 쫓겨 올바른 학습을 접하기 쉽지 않다. 그리고 같이 연주를 하기 위한 파트너를 구하는 것도 쉬운 일이 아니다. 제안된 시스템은 독학 시 가장 문제점가 되는 꾸준한 연습과 체계적인 연습의 부족이라는 두 가지 단점을 모두 극복할 수 있다. 본 논문에서는 베이스 기타를 컴퓨터에 연결하여 음정을 인식한다. 피치 추출 알고리즘 중 하나인 자기상관 함수를 사용하여 베이스 기타에서 추출한 음정 데이터와 미디에서 추출한 음정 데이터 간의 비교를 통해 효율적인 연습 환경을 제공한다.
분리유한요소법과 ILU 예조건화 기법을 이용한 3차원 난류 유동해석
안영규(Youngkyoo Ahn),최형권(Hyoung Gwon Choi),용호택(Ho-Taek Yong) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
A segregated finite element method based on SIMPLE algorithm has been developed in order to solve three dimensional flows around a blunt body. This study is the extension of the two dimensional segregated finite element algorithm proposed by Choi & Yoo (1994). For the validation of the algorithm, steady flows around a sphere are solved at various Reynolds numbers. The results agree well with the existing numerical and experimental results. For the analysis of turbulent flow, κ-ω model is adopted for the present algorithm. The turbulence model is tested by solving a pipe flow at Re = 40,000. Lastly, turbulent flows around an Ahmed model are solved for various shapes and the results are compared with the existing experimental and numerical results.
ANSYS Fluent를 이용한 Lithium-ion Battery 해석
안영규(Youngkyoo Ahn) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
In a xEV system, a battery pack is composed of numerous battery cells and the performance, life and safety of a battery is very sensitive to temperature. Heat arises due to ambient environment, joule heating and electro-chemistry and the thermal management of battery cell is very important. ANSYS Fluent provides three kinds of electro-chemistry models for lithium-ion battery simulations. This paper introduces the numerical model approach method by solving NTGK Empirical Model<SUP>(5)~(7)</SUP>, Equivalent Circuit Model<SUP>(10)</SUP>, and Newman electrochemistry Model<SUP>(1),(2)</SUP> available in ANSYS Fluent. For the validation of the model, a single battery cell is solved at various conditions. The results well agreed with the existing numerical and experimental results. An additional co-simulation analysis was carried out to predict the thermal state inside of the battery pack due to the electrochemistry, fluid flow, and thermal conditions.
고체열원을 포함한 밀폐된 공동 내의 복합열전달에 대한 연구
안영규(Youngkyoo Ahn),최형권(Hyoung-gwon Choi) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
In the present study, a conjugate heat transfer problem inside a cavity with a solid body, where constant heat flux is generated, is investigated. A conduction heat transfer problem inside the solid body is automatically coupled with natural convection inside the cavity by using a finite element formulation. A SIMPLE type algorithm is adopted for the finite element solution of the incompressible Navier-Stokes equation. Effect of various parameters including the position, intensity and material property of the solid body on the heat transfer characteristic inside the cavity is numerically studied by examining temperature and velocity fields.