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정상유동 장치에서 유동 특성 평가 방법에 대한 연구(1) - 문제의 제기
박찬준(Chanjun Park),엄인용(Inyong Ohm) 한국자동차공학회 2015 한국 자동차공학회논문집 Vol.23 No.1
This paper is the first investigation on the evaluation methods of flow characteristics in the steady bench. For this purpose, several assumptions used in the steady flow evaluation are examined, comparing the measured and/or processed results by the conventional impulse swirl meter with the ones by the real velocity through a particle image velocimetry. The results show that the most questionable assumption is the solid rotation of swirl. With regard to this assumption, the flow characteristics by the conventional methods are distorted seriously by both of the eccentricity of the swirl center and non-uniform velocity profile along the cylinder radial direction. In addition, the cylinder axial velocity distribution also has the great effect on the flow characteristics.
정상유동 장치에서 유동 특성 평가 방법에 대한 연구(4)
박찬준(Chanjun Park),성재용(Jaeyong Sung),엄인용(Inyong Ohm) 한국자동차공학회 2016 한국 자동차공학회논문집 Vol.24 No.2
This paper is the forth investigation on the evaluation methods of flow characteristics in a steady flow bench. In the previous works, it was concluded that the assumption of the solid rotation might cause serious problems and both of the eccentricity and the velocity profile distort the flow characteristics when using the ISM at 1.75B plane. Also particle image velocimetry (PIV) measurement at this position showed that the real velocity profile was far from the assumption of ISM evaluation. In this paper, the planar velocity profiles were measure from 1.75B to 6.00B position by PIV and the characteristics were examined according to the valve angles and lifts for further investigations about the effect of the position on the velocity profile. The results show that 26° valve angle is always an unique exceptional case in all aspects. If the valve angle is 21° and below, the planar velocity profiles according to the lift and the position are similar to each other, however, the tangential velocity curves along with the radial direction have common tendencies up to 16° angle. Also the well arranged swirl behaviors are generally observed at the position above 3.00B and the velocity contour lines come closer to the concentric circle as the valve lift increases. In addition, the gradient of tangential velocity along with the radial direction from the swirl center becomes stable and constant as the position goes downstream. Concurrently the velocity gradient is larger to the eccentric direction of the center. In the meantime the tangential velocity curves along with the radial direction are irregular and various at 1.75B, however, they become regular and reach higher level as the evaluation position goes downstream. At this time the curves of 4.50B are the best fitted to the ideal one. On the other hand in an exceptional case, 26°, the velocity contours are very complicated over 6mm valve lift regardless the position and the gradient increases to the opposite direction of the eccentric center. Also, 6.00B is a best fitting position in the geometrical cylinder center base. With respect to the swirl center, the distribution range of centers for 1.75B is different to that for the other positions and the eccentricities of this plane are larger regardless the valve angle. After 1.75B, there is no certain tendency in the center position change according to the valve angle and lift. Additionally, the eccentricities are not sufficiently small to neglecting the effect on ISM measurement.
대학생 참여 중심의 적정기술 활동 활성화를 위한 산학단 협력모델 연구:
박찬준(Chanjun Park),김도연(Doyeon Kim),윤준석(Junseok Yoon),김경외(Keungoui Kim),이준민(Junmin Lee),황준석(Junseok Hwang) 적정기술학회 2018 적정기술학회지(Journal of Appropriate Technology) Vol.4 No.1
적정기술활동이 참여 학생에게 주는 교육적 효과가 크다는 논의가 지속되는 가운데, 적정기술을 활용한 학생 참여 중심의 봉사활동 프로그램을 기획하는 대학이 늘고 있다. 그러나 적정기술과 관련된 여러 특성들을 고려하였을 때, 기존의 적정기술을 활용한 봉사활동의 접근 방식에는 크게 두 가지 한계점이 존재한다. 먼저, 학생 중심으로 적정기술 활동을 실시할 경우, 개별 적정기술 프로젝트의 지속성을 유지하기 어렵다. 대학생들은 보통 방학을 활용해서 봉사활동을 참여하게 되는데, 이러한 일회성 사회봉사 활동은 적정기술이 추구하는 지속가능성 측면에 부합하지 않는다. 또한, 전문지식의 부족과 실무 경험의 결여는 적정기술활동에 대한 신뢰성 문제를 야기할 수 있다. 적정기술은 현지인들의 삶과 밀접하게 연관되어 있기 때문에, 해당 기술의 완성도나 단일 제품으로서의 품질이 충분하지 않을 경우, 오히려 부정적인 효과를 야기할 수 있기 때문이다. 이러한 측면에서 “2017 하계 SNU 공헌유랑단 서울대-한수원 베트남 빈딘 봉사단” 활동은 기존의 문제점들을 산학연 협력이라는 형태로 극복했던 사례라고 볼 수 있다. 본 사례의 경우, 서울대학교, 한국수력원자력, 서울대학교 글로벌사회공헌단이 협동하여 활동지역에 적합한 적정기술을 공급하기 위해 각자의 역할을 수행했고, 그 결과 대학생 참여 중심적 봉사활동이 가진 한계점을 보완한 것으로 나타났다. 이에 본 연구에서는 위 사례를 분석하여 적정기술 기반의 산학단 협력모델을 제안하고자 한다. 분석 결과, 대학은 기술의 연구개발과 문제해결형 인재 육성을, 기업은 자금지원 및 기술지원을, 사회공헌단은 현지와 기술 연구 집단, 기업, 학생을 연결하는네트워크 허브로서의 역할을 수행했을 때 대학생 참여 중심 적정기술 활동의 교육적, 기술보급적 목적을 달성할 수 있음을 확인하였다. 본 연구를 통해 보다 많은 연구집단, 기업, 사회공헌단이 대학생 참여 중심의 적정기술 활동에 적극적으로 참여할 수 있기를 기대한다. Due to its educational effect on students who participate in appropriate technology (AT) activities, more number of universities started to promote voluntary service programs using AT. However, there are two limitations on existing voluntary service programs using AT in consideration of various features of AT. Firstly, the consistency can be hardly maintained as most students participate as a one-time event. Secondly, the lack of professional knowledge and experience may cause a serious credibility problem. Since AT is closely related to the life of local people, inconsistency and imperfect quality of AT can cause a negative effect. In this context, we studied the case of “2017 Summer SNU Social Responsibility Activity SNU-KHNP Corps in Binh Dinh Vietnam” as it is shown to be a good sample that overcame the existing problems through “Corporate-University-Institute” collaboration. For this case, Seoul National University, Korea Hydro Nuclear Power, and Institute for Global Social Responsibility collaborated for the installment of AT. As a result, we found out that the goal of AT activities could be achieved when the role of each agent was clarified: Company for financial and technological support, university for technology and human resource development, and institute for connecting all agents and local sites.