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임경수(Kyoungsoo Lim),안상민(Sangmin Ahn),오세욱(Sewook Oh) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
This paper presents a stabilizing filter design method for MDPS (Motor Driven Power Steering) system. The role of the stabilizing filter is to avoid the operating resonance frequency of MDPS system. Generally, the natural frequency of MDPS system is approximately 10 to 20 ㎐. MDPS system which is changed for performance improvement and cost reduction has to be optimized by the stabilizing filter for system stability, because the natural frequency of MDPS system is dependent on mass and stiffness of all parts. To optimize the stabilizing filter, this proposed method requires the natural frequency of MDPS system in a vehicle condition. In this paper, the proposed system identification approach uses a set of discrete sine waves each multiplied by a window function to measure the transfer functions of MDPS system and all torque signals on time domain are transformed to the amplitude on frequency domain by using FFT (Fast Fourier Transform). The stabilizing filter is designed by the natural frequency that is searched from upper method and the final effect is proved in a vehicle condition.
Rasch 모형과 요인분석을 활용한 대학생 토론능력 평가도구 개발과 타당화 연구
이연주(Lee Yeonjoo),임경수(Lim Kyoungsoo) 한국문화융합학회 2020 문화와 융합 Vol.42 No.9
본 연구는 대학생의 토론능력 평가도구를 개발하고 이를 검증하기 위해 실시되었다. 이를 위해서 토론능력과 토론능력의 평가요소를 구분할 필요가 있다. 선행연구 분석과 전문가 협의를 통해 토론능력 평가요소를 ‘논리적 구성력’과 ‘표현전달력’으로 추출하였다. 추출된 평가요소를 교수자가 관찰하여 평가가 가능하도록 토론자의 토론 언어와 행동을 측정하는 평가문항으로 수정하였다. 대학생의 토론능력 평가를 위해 논리적 구성력과 표현전달력에 해당하는 문항으로 평가도구를 구성하였다. 토론능력 평가도구의 객관성을 확보하기 위해 예비조사와 본 조사를 실시하였다. Rasch 모형과 탐색적 요인분석, 확인적 요인분석을 통하여 평가도구의 신뢰도와 타당도를 확보하였고 최종 13문항으로 구성된 평가도구를 개발하였다. 본 연구는 교수자가 토론 교육현장에서 대학생의 토론능력을 평가하기 위한 객관적 토론능력 평가 도구를 제시하였으며, 논리적 구성력과 표현전달력의 중요성을 재확인한데에 의의가 있다. This study was conducted to develop and verify the discussion ability assessment tools of university students. To this end, it is necessary to distinguish between the evaluation factors of debate ability. Through prior research analysis and expert consultation, the elements of the evaluation of debating ability were extracted as ‘logical composition’ and ‘expression delivery.’ The extracted evaluation elements were modified to measure the debater’s discussion language and behavior so that the professor could observe and evaluate them. To evaluate the debate ability of the university students, the assessment tools were organized with questions corresponding to logical composition and expressive delivery. Preliminary surveys and main surveys were administered to ensure objectivity of the assessment tools for discussion ability. The reliability and validity of the assessment tools were secured through the Rasch model and exploratory and confirmatory factor analysis, and the assessment tools composed of the final 13 questions were developed. This study is meaningful in that the professor presented an objective discussion ability evaluation tools to evaluate the debate ability of university students at the debate education site and reaffirmed the importance of logical composition and expressive delivery.
자율주행 차로 유지 성능 개선을 위한 RWS 제어 전략
배상홍(Sanghong Bae),권재준(Jaejoon Kwon),민경욱(Kyoungwook Min),임경수(Kyoungsoo Lim),오세욱(Sewook Oh) 한국자동차공학회 2022 한국자동차공학회 부문종합 학술대회 Vol.2022 No.6
This paper proposes a new control strategy of RWS system for improving lane following performance of autonomous driving, not the well-known general control strategy of the RWS system. The general control strategy of the RWS system is well known as out-of-phase control to increase steering convenience at low speeds and in-phase control to increase vehicle stability at mid-high speeds. The new control strategy is proposed based on the fact that the cornering characteristic of the vehicle shows a tendency to oversteer when performing out-of-phase control instead of in-phase control at mid-high speeds. The new control strategy increases vehicle responsiveness and ultimately minimizes the change in front wheel steering fluctuation by performing RWS out-of-phase control in the mid-high speeds on-center area corresponding to the lane following situation of autonomous driving. The effectiveness of the new control strategy was verified through an actual vehicle test, and based on this result, it was confirmed that this control strategy was helpful in improving the lane following performance.