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그레이 모델예측을 고려한 ABS용 슬라이드 모드 제어기
이재선(Jaeseon Lee),성상만(Sang man Seong),강기호(Ki Ho Kang) 한국자동차공학회 2013 한국자동차공학회 지부 학술대회 논문집 Vol.2013 No.5-2
This paper presents a sliding mode control design for passenger vehicle anti-lock braking system(ABS) considering grey model prediction. Using a quarter wheel model, the controller for ABS is designed to track the desired wheel slip ratio. Te controller designed predicts the upcoming slip ration and keeps it within a desired level. The effect of controller has been evaluated by computer simulation through MATLAB m-file coding. The results show that the controller is capable of achieving faster response and better overshoot performance than usual sliding mode controllers.
복부 컴퓨터 단층촬영영상에서 다중 확률 아틀라스 기반 형상제한 그래프-컷을 사용한 신실질 자동 분할
이재선(Jaeseon Lee),홍헬렌(Helen Hong),나군호(Koon Ho Rha) 한국컴퓨터그래픽스학회 2016 컴퓨터그래픽스학회논문지 Vol.22 No.4
본 논문에서는 복부 CT 영상에서 다중 확률 아틀라스 기반 형상제한 그래프-컷을 사용한 신실질 자동 분할 방법을 제안한다. 제안 방법은 다음의 세 단계로 구성된다. 첫째 신실질의 다양한 형상정보를 이용하기 위해 피질기반 유사정합을 통한 다중 확률 아틀라스를 생성한다. 둘째, 최대사후확률 추정을 통해 그래프-컷의 초기 씨앗을 추출하고, 형상제한 그래프-컷을 통해 신실질을 분할한다. 셋째, 확률 아틀라스의 정합 오차를 줄이고 분할 정확도를 높이기 위해, 정합 및 분할을 반복적으로 수행한다. 제안방법의 성능을 평가하기 위해 정성적 평가 및 정량적 평가를 수행하였다. 실험결과 제안방법이 신실질과 유사한 밝기값을 갖는 주변 영역으로의 누출을 방지하여 개선된 분할 정확도를 보여준다. In this paper, we propose an automatic segmentation method of renal parenchyma on abdominal CT image using graph-cuts with shape constraint based on multi-probabilistic atlas. The proposed method consists of following three steps. First, to use the various shape information of renal parenchyma, multi-probabilistic atlas is generated by cortex-based similarity registration. Second, initial seeds for graph-cuts are extracted by maximum a posteriori (MAP) estimation and renal parenchyma is segmented by graph-cuts with shape constraint. Third, to reduce alignment error of probabilistic atlas and increase segmentation accuracy, registration and segmentation are iteratively performed. To evaluate the performance of proposed method, qualitative and quantitative evaluation are performed. Experimental results show that the proposed method avoids a leakage into neighbor regions with similar intensity of renal parenchyma and shows improved segmentation accuracy.
Hybrid Euler-Lagrangian 기법을 이용한 CO2 충돌 제트의 승화 현상 해석
이재선(Jaeseon Lee),곽송미(Songmi Kwak) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11
The flow and heat transfer characteristics of the novel gas-solid two-phase jet impingement are investigated computationally. When the high pressure carbon dioxide (CO2) flow passes through a nozzle or orifice, it experiences the sudden expansion and the rapid temperature drop occurred by Joule-Thomson effect. This temperature drop causes the lower bulk jet fluid temperature than the CO2 sublimation line, so dry-ice becomes formed. By using CO2 gas-solid mixture as a working fluid of jet impingement, it is expected the heat transfer enhancement can be achieved due to the low bulk temperature and the additional phase change latent heat. In this study, 2D CFD model is created to predict the cooling effect of gas-solid CO2 jet. The gas-solid CO2 flow is considered by Euler-Lagrangian approach of mixed phase and the additional heat transfer module is embedded to account for the sublimation phenomena of the solid state CO2. The jet flow and heat transfer performance of gas-solid CO2 jet is investigated by the variance of flow parameter like Reynolds number, solid phase concentration and jet geometries.