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최성호(Seongho Choi),이진구(Jinkoo Lee),김기영(Giyung Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recent trends of research & development for Vehicular Anti-lock Brake System (ABS) are focused on the NVH as well as braking/traction performance. For the conventional systems, we used On-Off control strategy, which is composed of pulse-up pressure rise, pressure dump and pressure hold mode. The main problems associated with the discrete (On-Oft) nature of this control are severe noise and vibration. Especially, among the three pressure modes of conventional control, the pressure pulse-up is the major source of noise and vibration. To reduce pulse-up noise & vibration of ABS, we introduce Linear Flow Control (LFC) concept, which allows continuous pressure rise mode instead of pressure pulse-up. Continuous pressure rise can be obtained by controlling the magnetic force of solenoid valve, which needs current control of the solenoid valve. In this regard, we proposed using Pulse Width Modulation (PWM) method to control the current and to compensate for the discrete nature of actuator dynamics by duty control. Another source of noise and pedal kickback during ABS action is excessive pumping of brake fluid caused by unnecessarily high motor speed. Because the level of noise and vibration caused by the motor is directly related with the motor speed, we introduced a new Motor Speed Control (MSC) method that could compromise pumping performance and noise. Our new concept ABS also archives better performance in stopping distance compared with conventional control method by reducing average pressure dump and maintaining optimal slip band. In this paper, we will present recent results of LFC & MSC for our new generation ABS in the view of performance and NVH.
거시변화 및 차주 특성을 반영한 주택담보대출 위험 예측모형
최성호(SeongHo Choi),지규현(ChangMoo Lee) 한국주택학회 2016 주택연구 Vol.24 No.2
본 연구에서는 로짓모형을 기반으로 거시환경 변화가 주택담보대출의 차주 불량률율 에 총량적 수준과 미시적 차주특성에 미치는 영향을 실증적으로 분석하였다. 불량률 예측모형은 차주특성 변수와 시점더미 변수를 독립변수로 두고 추정한 후, 시점더미 예측 치를 다시 시계열모형을 이용하여 추정하는 2단계 추정과정을 통해 도출하였다. 해당 모형은 거시환경 변화의 반영과 위험 집단을 세분화를 동시에 할 수 있는 장점을 가진다. 본 연구의 불량률 예측모형은 실증적인 측면에서 주택담보대출 불량률의 보다 정교 한 예측을 위해서는 거시환경변화에 따른 총량 자료와 미시자료를 동시에 고려할 필요성을 보여준다. 대수의 법칙에 따른 거시 예측모형은 특정 시점의 차주 특성을 반영하는데 한계를 보인다. 차주 특성의 또한 모형의 시뮬레이션 결과는 동일한 거시환경변화에서도 주택담보대출 차주의 특성에 따라 서로 다른 불량률을 보이는 것으로 나타난다. 따라서 정책적으로도 주택담보대출 위험 관리에는 개별 금융회사의 리스크 관리와 거시적 그리고 총량적 측면에서의 정책당국의 역할이 모두 중요하다. This paper makes a macro-micro combined model to forecast mortgage defect probability. The model consists of two-step procedure in which borrower’s characteristics and macroeconomic variables are included as independent variable. At the first step, we develope a binary choice model with time dummies, assuming that the defects probability is affected by both borrower’s characteristics and periodical variations. At the second step, we identify a time series model that forecasts the time dummy coefficients with macroeconomic independent variables. Since reflecting both macro and micro environmental information, the model has advantages in both sorting out a risk group at micro level and measuring a size of macroeconomic shock at aggregated level. The estimation results are statistically stable. It means that macroeconomic forecasting model, which is based on the laws of large number, seems to be showing mortgage borrower’s defect process on a limited way. Simulation study also shows that defect probability in a case of considering both macro level and micro level effects is approximately two times higher than in a case of considering only micro level effects. Therefore, both the authorities and individual companies have an important role to handle mortgage market risks.
펄스 폭 변조를 갖는 슬라이딩 모드 제어기를 이용한 차량의 슬립률 제어
최성호(SEONGHO CHOI),조동우(DONGWOO CHO) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.11_2
For the control of anti-lock brake system (ABS), a longitudinal four-wheel vehicle model with brake actuator is described and a sliding mode controller with pulse width modulation (PWM) method has been developed for passenger vehicles. In our research, we introduced actuator dynamics of solenoid-solenoid valve type in system equation and derived the sliding mode control input theoretically. We propose using PWM method to compensate for the discrete nature of actuator dynamics by duty control. The effectiveness of the proposed control algorithms was confirmed by vehicle test on an In-door test bench that was specially constructed for the purpose concerned<br/>
[차량운동성능부문] 차량 안정성 제어를 위한 추진 축 토크, 타이어 힘 및 차량 슬립각의 추정
최성호(SEONGHO CHOI),조동우(DONGWOO CHO) 한국자동차공학회 1999 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
In this paper, an extended Kalman Filter (EKF) is implemented to estimate the drive shaft torque, longitudinal and lateral tire force histories of 14 degree-of-freedom vehicle model. Prior knowledge of road properties or tire parameters is not required to implement the EKF, and all sensors are contained on the vehicle. The ability to determine tire forces and state estimates in this manner has major implications on the analysis and control of all types of ground vehicles. From the estimated values of tire forces, a straighforward estimation algorithm for vehicle slip ratio using HSRI-tire model is also proposed.
DramaQA: 계층적 질의응답과 함께하는 등장인물 중심 비디오 스토리 이해
최성호(Seongho Choi),온경운(Kyoung-Woon On),허유정(Yu-Jung Heo),장유원(Youwon Jang),서아정(Ahjeong Seo),이승찬(Seungchan Lee),이민수(Minsu Lee),장병탁(Byoung-Tak Zhang) 한국정보과학회 2021 정보과학회 컴퓨팅의 실제 논문지 Vol.27 No.1
본 논문은 비디오 스토리의 포괄적 이해를 위한 새로운 비디오 질의응답 데이터셋 DramaQA를 제안한다. DramaQA 데이터셋은 1) 인간지능의 인지 발달 단계에 기초한 인공지능 시스템에 대한 평가 지표로서의 계층적 질의응답 데이터셋과 2) 스토리의 지역적 일관성을 모델링하기 위한 등장인물 중심의 비디오 주석을 제공하는 것을 목표로 한다. DramaQA 데이터셋은 TV 드라마 “또 오해영”을 이용하여 제작되었으며, 23,928개의 다양한 길이의 비디오로부터 각각 4개의 난이도 중 하나에 포함되는 17,983개의 질의응답 쌍을 포함한다. 데이터셋은 등장인물 중심 시각적 주석이 되어있는 217,308장의 이미지들과 상호참조가 해결된 스크립트를 제공한다. 또한, 우리는 비디오 질의응답에 대한 등장인물중심의 표현을 효과적으로 학습하기 위한 Dual Matching Multistream 모델을 제안하고 DramaQA 데이터셋에 적용하여 등장인물 중심의 비디오 스토리 이해 방법을 제시한다. In this paper, we propose a novel video question answering (Video QA) task, DramaQA, for obtaining a comprehensive understanding of a video story. The DramaQA focuses on two perspectives: 1) hierarchical QAs as an evaluation metric based on the cognitive developmental stages of human intelligence, and 2) character-centered video annotations to model the local coherence of the story. Our dataset is built upon the TV drama “Another Miss Oh” and contains 16,191 QA pairs from 23,928 video clips of various lengths, with each QA pair belonging to one of four difficulty levels. We provide a total of 217,308 annotated images with rich character-centered visual annotations and coreference resolved scripts. In addition, we provide analyses of the dataset as well as a Dual Matching Multistream model which effectively learns character-centered representations of the video to answer questions about the video.
차량의 슬립률 제어를 위한 펄스 폭 변조를 이용한 비선형 슬라이딩 모드 제어기의 설계
최성호(SEONGHO CHOI),조동우(DONGWOO CHO) 한국자동차공학회 1998 한국자동차공학회 춘 추계 학술대회 논문집 Vol.1998 No.5_2
For the control of anti-lock brake system(ABS), a longitudinal four-wheel vehicle model with brake actuator is described and a sliding mode controller with pulse width modulation(PWM) method has been developed for passenger vehicles. In our research, we in troduce actuator dynamics in system equation and derive equivalent control input theoretically. We propose using PWM method to compensate the discrete nature in actuator dynamics by duty control. We check the stability of PWM controller for SMC theoretically and control algorithms, which are proposed in this paper, were verified by vehicle test on In-door test bench that is specially constructed for that use.<br/>