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디지탈 신호처리 기법을 이용한 맥동연소기의 소음원 규명에 관한 연구
김도원,조정길,이관수,오재응,Kim, D.W.,Cho, J.G.,Lee, K.S.,Oh, J.E. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.2
This paper presents a method for estimating the noise source contribution of a pulse combustion burner in a multiple input system where the input sources may be coherent each other. By coherence function method, it is found that the biggest part of the noise source in the pulse combustion burner is generated by the part of the combustion chamber. This analysis is modeled as three input / single output system because the noise generating mechanism of the pulse combustion burner is very complicated. The coherence function method is proved to be useful tool for the identification of noise source. The overall levels of the radiated source pressure by coherence function method are compared with those measured and calculated by the frequency response function approach. The experimental results have shown a good agreement with the results calculated by the coherence function method when the input sources are coherent strongly each other. The estimation of shield effect by FRF method indicates that significant reduction can be achieved in sound radiation if only transmission path generated by the part of combustion chamber is acoustically shield.
철도선로변 금속체의 전위분포 해석에 의한 접지설계 기준 수립
김도원(D.W. Kim),박종원(J.W. Park),박윤철(Y.C. Park),호명재(M.J. Ho),심건보(K.B. Shim) 한국철도학회 2014 한국철도학회 학술발표대회논문집 Vol.2014 No.10
전기철도 구간에서 전기동력차 및 전원공급 설비의 증가에 따라 차량 운행중의 정상상태 부하전류와 지락고장 등에 의한 고장전류의 증가에 따라 철도시설물에 이상전압으로부터 안전을 확보하고자 하는 대책으로 공통접지방식을 시행하고 있다. 그러나 시공의 현장에서 철도선로로부터 일정한 거리 또는 교량의 하부 등에 시설되는 울타리 등의 금속체에 대한 시공은 현장의 여건상 어려움이 많이 발생하고 있다. 따라서 본 연구에서는 철도선로의 연변에 시설되는 금속체에 대하여 차량 운행중의 정상상태와 고장상태에서 발생하는 전위분포를 측정하는 시험과 대지저항률의 변화에 따른 전위분포의 시뮬레이션을 통하여 인체에 미치는 영향을 검토하여 안전을 확보할 수 있는 접지설계 기준을 수립하고자 하였다. The power supply system of electric railway is consist of many electric facilities such as overhead contact line, power supply system, a signaling tract circuits, train control system and train communication system etc. Electric grounding systems are adopted for the protections of the human being and the damage of equipment from the overcurrent and the overvoltage by electrical accidents. In this paper, we deal with the standard of common grounding system for electrical railway system. Especially, grounding design for the metal structures in the electric railway. For the proposed paper, we tested the potential distribution of the metal structure in the electric railway system at the fields. And we analyzed the data from field tests and computer simulations for the effectiveness of the common grounding system in the electric railway system.
수냉식 화격자 유로 형상에 따른 냉각수의 정체 영역 및 체류 시간 변화
송동근(D.K. Song),김상복(S.B. Kim),박도원(D.W. Park) 한국전산유체공학회 2016 한국전산유체공학회지 Vol.21 No.2
Waste-to-energy facilities including incinerators are known as an efficient method to reduce wastes. In waste-to-energy facilities, more efficient cooling system is still needed for grates as the energy density of waste increased. For better cooling performance with the water-cooled grates, optimal design of cooling water pathways is highly beneficial. We performed numerical investigation on fluid flow and residence time of cooling water with change of the geometry of the cooling water pathway. With addition of round shaped guide vanes in the water pathway, the maximum residence time of flow is reduced(from 4.3 sec. to 2.4 sec.), but there is no significant difference in pressure drop between inlet and outlet, and average residence time at the outlet. Furthermore the flow stagnation region moves to the outlet, as the position of the round shaped guide vanes is located to the neck point of pathways.