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SMS를 활용한 교사와 학부모의 의사소통 실태 및 과제
차경수,조미헌,Cha, Kyoung-Soo,Jo, Mi-Heon 한국정보교육학회 2009 정보교육학회논문지 Vol.13 No.1
맞벌이 가정의 증가로 학부모는 교사와의 의사소통에서 시간 공간적으로 자유롭지 못하며, 교사도 학급당 많은 인원수와 업무과중 등으로 학부모와 의사소통이 잘 이루어지지 못하고 있다. 이러한 상황을 극복할 수 있는 수단으로서 SMS를 활용한 교사와 학부모의 의사소통 실태를 분석하고 해결해야 할 과제를 알아보았다. SMS 활용 실태에서 아동에 대한 정보 교류 및 교육 활동을 위해 SMS가 필요하다는 대답이 높았으며, 교사는 아동에 대한 교육 정보 교류를, 학부모는 생활 태도 향상에 효과가 있음을 지적하였다. 분석 결과를 바탕으로 담임에 대한 부담 해결, 담임과의 친숙함 형성, SMS 무반응 이유 탐색 및 대처 방안 마련, 학부모 요구에 맞는 정보 제공하기, 학부모의 답장률 높이기, 문자 용량 확대, 컴퓨터 온라인 접속 문제 등이 해결해야 할 과제로 파악되었다. With the increase of double-income families, parents are not free in terms of time and space in communicating with teachers. Also for teachers, with many students and heavy load of work, communication with parents has been poor. As a means for overcoming this kind of situation, this research examined the current status of communication between teachers and parents using SMS and problems to solve. The investigation of the actual conditions of SMS use showed that there was a high number of answers pointing out that SMS is needed for the exchange of information regarding children and educational activities, and teachers pointed out that the communication was effective for exchanging educational information regarding children whereas parents pointed out that it was effective in improving the children's attitudes. Based on the results of the analysis, the following was found as tasks to be solved: preparing a plan for revitalizing SMS use, solving the burden that parents have in communicating with teachers, becoming more friendly with teachers, investigation of the reason why there is no response regarding SMS and preparing countermeasures, providing information appropriate to what parents want, increasing the reply rate of parents, expansion of text capacity, and trouble with getting online with a computer.
헤어핀 권선을 이용한 EV 구동용 WFSM의 출력 밀도 개선 설계
차경수(Kyoung-Soo Cha),박진철(Jin-Cheol Park),채승희(Seung-Hee Chai),홍정표(Jung-Pyo Hong) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11
The rare earth material are dependent on imports from China for unstable supply and demand. Therefore the wound field synchronous motor (WFSM) which doesn’t use rare earth material is being studied. The most commonly used wire shape is circular, with fill factor of 40%. If the fill factor can be increased, the slot area can be decreased. The hair-pin winding used wire shape is square and fill factor of 60%. So, if the slot area is designed for using hair-pin winding, it can be designed smaller than slot area of initial model. By reducing the slot area, it is possible to increase the stator inner diameter and the rotor outer diameter. Then it is possible to reduce the stack length while maintaining the same torque. In conclusion, it is possible to reduce the motor weight and volume. Moreover, by designing a square shaped slot, it is possible to increase the width of teeth. This also reduces the saturation level, which in turn reduces the total harmonic distortion (THD) of the back electromotive force (BEMF). Therefore, by using a hairpin winding in motor design, the same output can be maintained while the volume and weight is decreased. The power density is increased. In this paper, by using a hairpin winding, stack length is reduced by 10% compared to the initial model while maintaining the same output. The initial and improved model is compared by calculating the power density and efficiency of the motor by using a Two-Dimensional Finite Element Method (2-D FEM).
반응표면설계법을 이용한 자동차 펌프용 IPMSM의 토크리플 및 THD 최적설계
박수환(Soo-Hwan Park),홍주희(Ju-Hee Hong),박진철(Jin-Cheol Park),차경수(Kyoung-Soo Cha),홍정표(Jung-Pyo Hong) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5
This study presents optimum design of IPMSM for vehicle pump using Response Surface Methodology(RSM). In the electric motors of vehicle system, reducing noise/vibration is one of the most important issue in designing electric motors. In initial design, pole/slot combination of the prototype is determined by using Noise & vibration order to reduce radial force in airgap of the motor. The optimization conducted by using RSM. The objective functions are back-electromotive force(BEMF) and Total Harmonic Distortion(THD) of the BEMF. The design variables are slot open, eccentricity and pole angle. The validation of the electric motor will be verified by 2-D FEA.
김재의(Jae-Yui Kim),차경수(Kyoung-Soo Cha),박민로(Min-Ro Park),임명섭(Myung-Seop Lim),홍정표(Jung-Pyo Hong) 한국자동차공학회 2016 한국자동차공학회 학술대회 및 전시회 Vol.2016 No.11
Recently, an interior permanent magnet synchronous motor (IPMSM) which has high power density and efficiency has been attracting attention for electric vehicle (EV) traction motor. Also motor design for smaller size and higher rotating speed is latest trend because it can make more space. But in high rotating speed, an induced voltage can exceed the DC link voltage. In that case, it can be difficult to control the motor and makes lower torque due to lack of voltage. In this paper, an improvement design for initial model of EV traction motor is conducted to reduce induced voltage value through shape change. In case of stator, various shape of chamfers are applied and in case of rotor, an eccentricity is applied. For each case, 2-D FEM is used for verification for value of an average torque at base rpm and a maximum induced voltage at maximum rpm. Finally, an improvement model is designed which has an induced voltage that does not exceed the DC link voltage.
Bar Winding을 사용한 EV용 IPMSM의 AC 저항 저감을 위한 고정자 최적 설계
임재연(Jae-Yeon Lim),차경수(Kyoung-Soo Cha),박수환(Soo-Hwan Park),김재현(Jae-Hyun Kim),임명섭(Myung-Seop Lim) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11
Bar winding is widely applied to EV traction motors because of its high fill factor. However, bar winding causes AC resistance to increase due to its large cross-sectional area of the conductor. For high efficiency, AC resistance must be reduced. Therefore, this paper proposes a stator optimal design method for EV traction motors to reduce AC resistance. First, the design factors which affect the output power and efficiency of the motor are determined by the analysis of variance. Next, the experimental points are determined by using Latin hypercube sampling, and use a Kriging surrogate model to proceed with the optimal design. As a result, we compare the efficiency of the target motor and the optimal design motor calculated through finite element analysis.