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CFD 를 이용한 PZEV 대응 배기 매니폴드의 유동 해석에 관한 연구
김대우(Daewoo Kim),곽호철(Hochul Kwak),박심수(Simsoo Park) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
As the current and future emission regulations become stringent, the research of exhaust manifold and CCC has been the subject of increasing interest and attention. This study is concerned with the systematic approach to improve catalyst flow uniformity and light-off behavior through the basic understanding of exhaust flow characteristics. Computational approach to the unsteady compressible flow for exhaust manifold of conventional cast type, stainless steel bending type and modified bending type and 900 cell CCC system of a 4-cylinder DOHC gasoline engine for PZEV was performed to investigate the flow distribution of exhaust gases. In this study, through calculation, the effects of geometric configuration of exhaust manifold on flow structure and its maldistribution in monolith were mainly investigated to understand the exhaust flow patterns in terms of flow uniformity. Based on the design guidance resulting from this fundamental study, the flow uniformity of stainless steel bending type and modified bending type exhaust manifold was compared with that of the cast type one.
김대우(Daewoo Kim),박영호(Youngho Park),이형철(Hyeongcheol Lee) 한국자동차공학회 2007 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
This paper propose a new method of vehicle yaw rate sensor offset compensation. MEMS yaw rate sensor is popular among industrial fields for low cost, compact size and high performance, but it also has a serious shortage, the electric drift phenomena. The electric drift produces sensor offset that is one of the major factor of vehicle control error. This paper employs fuzzy logic controller for deciding weighting factors of two different methods to compensate MEMS yaw rate sensor offset. The first sensor offset compensation method is the sequential compensation and the second is the bicycle model based compensation. The fuzzy logic controller is based on the Mamdani fuzzy inference engine that is the most popular stuff and some simulation results are presented.
입출력 변수 조작에 의한 임베디드 소프트웨어 테스트 방법
김대우 ( Daewoo Kim ),정기현 ( Kihyun Jung ),최경희 ( Kyunghee Choi ) 한국정보처리학회 2005 한국정보처리학회 학술대회논문집 Vol.12 No.1
임베디드 소프트웨어가 날이 갈수록 그 규모가 커지고 복잡해짐에 따라 임베디드 소프트웨어의 품질에 대한 검증 및 테스트는 중요한 문제로 부각하고 있다. 임베디드 소프트웨어의 신뢰성을 확보와 비용절감을 위한 테스트 자동화 시스템의 개발이 필요하다. 이 문서는 테스트 자동화 시스템을 구축하는 과정에서 테스트 대상인 임베디드 시스템의 입출력 변수들의 조작을 통하여 시스템 의존적인 부분을 효과적으로 일반화 시키는 방법을 제시한다. 이 방법을 통하여 테스트 명령을 간소화 할 수 있었으며 테스트 자동화 시스템의 모델을 보다 일반적이고 쉽게 표현할 수 있었다.
Aqueous Hydrogel System of One-Dimensional Carbon Materials
Daewoo Kim(김대우) 한국고분자학회 2021 한국고분자학회 학술대회 연구논문 초록집 Vol.46 No.1
The preparation of carbon materials based hydrogels and their viscoelastic properties are essential for their broad application and scale-up. However, existing studies are mainly focused on graphene derivatives and two-dimensional materials, and the behavior of one-dimensional (1D) materials such as graphene nanoribbon (GNR) and carbon nanotubes (CNTs) remains elusive. Poor dispersion of the 1D materials in the solvent is one of the key bottlenecks for utilizing the materials in many applications. Herein, the dispersion of the 1D materials in an aqueous system is suggested and its unique assembly behavior is systematically investigated. Particularly, we demonstrate the concentration-driven gelation of oxidized GNR (graphene oxide nanoribbon, GONR) and the GONR hydrogels exhibit viscoelastic shear-thinning behavior and can be shear-coated to form large-area GONR films on substrates. The hydrogel system also can be used