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특성함수와 피로해석을 이용한 로워컨트롤암의 형상최적설계
박영철(Youngchul Park),이동화(Donghwa Lee) 한국자동차공학회 2005 한국 자동차공학회논문집 Vol.13 No.1
The current automotive is seeking the improvement of performance, the prevention of environmental pollution and the saving of energy resources according to miniaturization and lightweight of the components. And the variance analysts on the basis of structure analysis and DOE is applied to the lower control arm. We have proposed a statistical design model to evaluate the effect of structural modification by performing the practical multi-objective optimization considering weight, stress and fatigue life. The lower control ann is performed the fatigue analysis using the load history of real road test. The design model is determined using the optimization of acquired load history with the fatigue characteristic. The characteristic function is made use of the optimization according to fatigue characteristics to consider constrained function in the optimization of DOE The structure optimization of a lower control ann according to fatigue characteristics is performed. And the optimized design variable is D=47mm, T=36mm, W=12mm. In the real engineering problem of considering many objective functions, the multi-objective optimization process using the mathematical programming and the characteristic function is derived an useful design solution.
박영철(Park Youngchul) 계명대학교 사회과학연구소 2004 한국사회과학연구 Vol.23 No.1
If we forcast the demand for the traffic of the subway system in Daegu, we can efficiently manage the manpower and the facilities of the city. The forcasting is implemented through autoregressive-moving average process and Winters' additive seasonal exponential smoothing. If it had not been for the arson in the subway in 1993, the daily transportation would slightly have increased. The demand for the subway system is high in spring and in fall, and low in summer and in winter.
박영철(Youngchul Park),이동화(Donghwa Lee) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Requirement terms in the development of automobile part are progressed about light weight, damage prevention by fatigue, and safety of product. Already, The previous study was gained suitably the good result about light weight in the expected period of this time when they changed the metal of lower control arm. But in the case of automobile part, it was concerned with life of people. And in the result, the fatigue life is very important. In this requirement, when we drive a car, our car is applied to the cycle load. Estimation of the fatigue properties must have respect to the design process. In these days of rapidly growth. this study is help to competition ability of automobile industry and will bring forth a large safety property and fast development effect.
박영철(Youngchul Park),이권희(Kwonhee lee),이동화(Donghwa Lee),이강영(Kangyoung Lee) 한국자동차공학회 2003 한국 자동차공학회논문집 Vol.11 No.3
Recently, the weight reduction of vehicle influences its environment problems and performances. It is a trend that a lot of parts have been currently changed to an aluminum alloy from steel materials. In this study, the shape optimization using an orthogonal array is performed to determine the design of the knuckle which is a part of suspension system. With the material of the weight reduction was achieved by satisfying the constraints of a strength requirement. The orthogonal array of L18 is introduced to find the optimum design variables that considers the shape of the knuckle. The characteristic function composed of the objective and the construct is defined to the feasibility. Comparing to the weight of the initial design with steel materials that of optimum design with aluminum alloy material is reduced by 60%.
박영철(Youngchul Park),박동성(Dongsung Park) 한국자동차공학회 2000 한국 자동차공학회논문집 Vol.8 No.3
Nonlinear transient analysis is executed to obtain the temperature distribution, and to evaluate the thermal stress of brake drum by using FEA(finite element analysis). The result induces the reason why hair crack and the cause of drum failure occurs and the way how stress of drum decreases. The temperature of drum is in proportion to the drum thickness and it processes nonlinear changes at every points of drum. The higher bulk temperature raises, the more stress difference between inner surface and outer surface makes and the highest bulk temperature is at the corner section. It is necessary for the diminishment of the drum stress to make air flow, between drum and rim, move lively and use the materials of higher conductivity. The hair crack and the cause of drum failure seem to be started at the near corner section.
효율적인 압축 알고리즘을 이용한 실용화 수준의 DVR 시스템
박영철(Youngchul Park),안재기(Jaeki Ahn) 한국정보과학회 2004 정보과학회 컴퓨팅의 실제 논문지 Vol.10 No.3
본 논문은 실용화 레벨에서의 디지털 영상기록 (Digital Video Recording: DVR) 구현을 기술한다. 또한 입력 영상을 배경과 목표물 영역의 두 가지 영역으로 분리 처리하여 분리된 영역별로 중요도를 고려하여 서로 다른 압축 기법을 적용함으로써 효율적인 압축부호화를 수행할 수 있는 방안을 제안한다. 본 알고리즘은 영상 압축 부호화 기법으로서 영역분할을 통해 Macro block 단위로 물체 영역과 배경 영역을 재구성해서 부호화에 이용하는 방식이다. 제안된 알고리즘은 매우 효율적인 압축 성능을 보여주며, 저 전송률 상황에서도 높은 질의 영상을 복원할 수 있다. We describe a practical implementation of DVR (Digital Video Recording) system. And we propose a new image compression algorithm, that input video signal is divided into two parts, a moving target and a non-moving background part to achieve efficient compression of image sequences. This algorithm reorganizes a target area and a back-ground area by use of Macro Block(MB) unit on encoding scheme. The proposed algorithm allows high quality image reconstruction at low bit rates.
박성현(Seonghyeon Park),강홍재(Hongjae Kang),박영철(Youngchul Park),이종광(Jongkwang Lee) 한국추진공학회 2020 한국추진공학회지 Vol.24 No.4
Hypergolic propellants have been widely used for space propulsion systems based their long-term storability and high ignition reliability. Since conventional hypergolic propellants are highly toxic and carcinogenic, handling and operating costs are significant. To overcome the drawbacks, numerous studies have been actively performed to develope new hypergolic propellants, ensuring that the combinations are high performance, low toxicity and low environmental impact. In the present study, a comprehensive survey was conducted to summarize the research and development of green hypergolic propellants involving hydrogen peroxide, nitric acid, and ionic liquids.
박한석(Hanseok Park),박영철(Youngchul Park),이권희(Kwonhee Lee),김영준(Youngjun Kim),김종규(Jongkyu Kim) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
Recently developed automotive components are getting lighter providing a higher fuel efficiency and performance. Following the current trend, this study proposes a structural optimization method for the lower control arm installed at the front side of a Vehicle. Lightweight design of lower control arm can be achieved through design and material technology. In this research, the shape of lower control arm was determined by applying the optimization technology and aluminum was selected as a steel-substitute material. Strength performance is the most important design requirement in the structural design of a control arm. This study considers the static strength in the optimization process. For the optimum design, the durability analysis is performed to predict its fatigue life. In this study, the kriging interpolation method is adopted to obtain the minimum weight satisfying the strength constraint. Optimum designs are obtained by the in-house program, EXCEL-Kriging. Also, based on the optimum model obtained for the static strength, the optimization of Index of Fatigue Durability is carried out to get th optimum fatigue performance.