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연료전지 자동차의 물탱크 해빙과정에 대한 수치해석적 연구
김학구,정시영,허남건,임태원,박용선 대한설비공학회 2007 설비공학 논문집 Vol.19 No.8
Good cold start characteristics are essential for satisfactory operation of fuel cell vehicles. In this study, the melting process has been numerically investigated for a water tank used in fuel cell vehicles. The 2-D model of the tank containing ice and plate heaters was assumed and the unsteady melting process of the ice was calculated. The enthalpy method was used for the description of the melting process, and a FVM code was used to solve the problem. The feasibility study compared with other experiment showed that the developed program was able to describe the melting process well. From the numerical analysis carried out for different wall temperatures of the pate heaters, some important design factors could be found such as local overheating and pressurization in the tank.
모니터 화면 내 활성화된 동영상 재생기 영역 검출 기법
김학구,송병철,Kim, Hak Gu,Song, Byung Cheol 대한전자공학회 2013 전자공학회논문지 Vol.49 No.11
본 논문은 모니터나 스마트TV 등에서 재생 중인 동영상 재생기의 창 영역을 정확하게 검출하는 기법을 제안한다. 단순히 시간적 차이 유무로 판단하거나 운영체제로부터 정보를 가져오는 기존 기법들과 달리, 제안하는 동영상 재생기 검출 기법은 영상 신호의 시공간적 특성 및 꼭지점 검출 필터를 이용하여 매우 정확하게 재생기 영역을 검출할 수 있다. 먼저, 영상 신호의 시간적 특성을 이용하여 재생기 창의 초기 영역을 설정한 뒤, 그 초기 영역을 기반으로 영상의 공간적 특성인 에지 정보와 꼭지점 검출 필터를 이용하여 재생기 창 영역의 네 꼭지점들의 위치를 계산한다. 모의실험을 통해 제안하는 기법이 빠른 연산 속도와 정확한 검출 성능을 보임을 확인하였다. This paper presents a detection algorithm that accurately finds the active area of a video player on monitors or smart TVs. Unlike the previous approaches, temporal difference-based detection algorithms or hooking programs, the proposed detection algorithm can locate the active video player by using the spatial and temporal correlation and a corner detection filter. First, an initial location of the video player is found using conventional temporal difference-based detection. Then, starting from the initial location, the four corners of the active video player are detected by the spatial edge information and the corner detection filter. The experimental results show that proposed algorithm provides fast detection speed and high accuracy.
Modeling, validation and energy flow analysis of a wheel loader
김학구,오광석,고경은,김판영,이경수 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2
This paper presents a wheel loader simulation model, validation results and energy flow analysis. The developed simulation model will facilitate the performance evaluation and optimization process in the development stage of a prototype wheel loader. The wheel loader simulation model consists of mechanical and hydraulic powertrain model, multi-body dynamic model and working part dynamic model. The multi-body dynamic model is simplified since the effect of pitch and roll motion of the wheel loader on the energy flow of the powertrain and hydraulic actuator systems is insignificant, a simplified planar model for the dynamic vehicle is good enough for the objective of this study. Every component is modeled and integrated in a simulation package developed using Matlab/Simulink. The simulation model has been validated using experiment data and the validation results show that it effectively represents the actual dynamic characteristic of the target wheel loader. The verified simulation model will be used as a virtual platform to evaluate the performance of alternative powertrain models such as a dual-clutch transmission and hydrostatic transmission. An advanced control system can also be implemented and evaluated using the virtual platform.