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김현일(Hyun-il Kim),이상민(Sang Min Lee),신명선(Myung Sun Shin),이종호(Jong Ho Lee) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.12
현재 생활문화 수준의 향상과 소득 증대에 따라 환경오염에 대한 관심이 증가하고 있다. 또한, 수질오염에 대한 규제가 강화되어 수질오염 방지 및 하수처리 효율 향상을 위한 연구가 지속적으로 수행되고 있다. 하수처리 효율을 향상시키는 방법 중 하나는 수처리조 내에서 용존산소량을 늘려주는 것이다. 본 연구에서는 용존산소량을 늘려주고, 산소 발생기에서 발생되는 버블의 크기를 작게 만들 수 있는 설계 방안을 제시한다. 마이크로버블 발생노즐로 유입되는 물과 공기의 유동 형태에 따라 선회 및 충돌을 생성시켜 버블의 크기를 미세하게 만들었다. 본 해석결과에서 충돌 방식의 경우 버블의 크기는 목표치를 만족하지 못하였다. 반면 선회를 이용한 노즐에서는 0~ 50μm 사이의 버블이 79.3%를 차지하고 있는 것으로 나타났다. 본 연구를 통해 개발된 마이크로버블 발생노즐은 하수처리 효율을 증대시킬 수 있을 것이다. Recently, with increasing standards of living and income, environmental pollution has attracted increased interest. On account of a revision to water pollution regulations, the improvement of sewage disposal efficiency was studied. One of the ways to improve the sewage disposal efficiency is to increase the dissolved oxygen content of water in the water treatment tank. In this study, we suggest a nozzle design using a spiral and a crash mode for generating micro bubbles and thus increasing the dissolved oxygen content of water. The micro bubbles through the spiral and crash flows are generated in the nozzle. In the design of the crash mode, the development goal with regard to the bubble size was not achieved. On the other hand, a bubble size of 0?50 μm accounted for 79.3% of all bubbles in the spiral mode. This study should contribute toward increasing the sewage disposal efficiency.
고분자 전해질 연료전지 유로의 수분배출 특성의 실험 및 해석적 평가
김현일(Hyun-il Kim),남진현(Jin Hyun Nam),신동훈(Donghoon Shin),정태용(Tae-Yong Chung),김영규(Young-Gyu Kim) 대한기계학회 2009 大韓機械學會論文集B Vol.33 No.2
Polymer electrolyte membrane (PEM) fuel cells are a promising technology for short-term power generation required in residential and automobile applications. Proper management of water has been found to be essential for improving the performance and durability of PEM fuel cells. This study investigated the liquid water exhaust capabilities of various flow channels having different geometries and surface properties. Threepass serpentine flow fields were prepared by patterning channels of 1 mm or 2 ㎜ width onto hydrophilic Acrylic plates or hydrophobic Teflon plates, and the behaviors of liquid water in those flow channels were experimentally visualized. Computational fluid dynamics (CFD) simulations were also conducted to quantitatively assess the liquid water exhaust capabilities of flow channels for PEM fuel cells. Numerical results showed that hydrophobic flow channels have better liquid water exhaust capabilities than hydrophilic flow channels. Flow channels with curved corners showed less droplet stagnation than the channels with sharp corners. It was also found that a smaller width is desirable for hydrophobic flow channels while a larger width is desirable for hydrophilic ones. The above results were explained as being due to the different droplet morphologies in hydrophobic and hydrophilic channels.
金賢鎰(Hyun-Il Kim),林涓贊(Youn-Chan Yim),朴大熙(Dae-Hee Park),張洪淳(Hong-Soon Chang),白壽鉉(Soo-Hyun Baek) 대한전기학회 2008 전기학회논문지 Vol.57 No.3
We studied on the dependency of parameters which those were used to design a ballast of ICP light source. These parameters were derived from Barkhausen criterion equation about the oscillating condition of ballast. Comparing with a change of turns, we can suggest that a change of l is suitable to control a Ip of an ICP light source . According to the Z-l equation, we can find an optimum rating power of ICP light sources corresponding to l.
폐열회수 환기장치의 열교환 효율 개선을 위한 전산수치해석
김현일(Hyun-il Kim),김재성(Jaesung Kim),박철우(Chulwoo Park),박경서(Kyungseo Park) (사)한국CDE학회 2012 한국CDE학회 논문집 Vol.17 No.1
In this paper, we performed numerical analysis to improve the heat exchange efficiency of wasted heat recovery ventilator which has a delivery and a exhaustion fan. One of the most important design factors that affect the efficiency of heat exchange is uniform counter-flow between inbound and outbound air flows. We had simulated several types of porous plates which were installed at air intake area. With plate having 45 degrees of installation angle and 15 mm diameter holes which are uniformly arranged, we can generate a uniform air flows at the area of porous media where inbound and outbound air flows are cross over. In addition, we installed a duct to reduce vortex flows at the outlet and to discharge exhaust airs rapidly. By using the proposed numerical assessment, we expect the improvement of the heat exchange efficiency of ventilator.
김현일(Kim Hyun-Il),유경돈(Yu Kyung-Don),서승직(Suh Seung-Jik) 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2
The purpose of this study is to present the applicability of photovoltaic systems for apartment buildings. Photovoltaic systems become far more attractive in apartment buildings that need so little electricity. Photovoltaic systems can also contribute to systems which provide ultra-reliable, ultra-high Quality, non-polluting, low operating cost, etc. So this study steps are as follows: This study was simulated to PV power generation of each azimuths and slopes per unit area according to the irradiance and ambient temperature. This case study for apartment buildings showed that Photovoltaic system can be applicable in some kinds of place, careful factors.<br/> Therefore this research is a basic study for clean energy source and present to applicability of photovoltaic systems for apartment buildings in preliminary design step.
김현일(Kim Hyun-Il),강기환(Kang Gi-Hwan),박경은(Park Kyung-Eun),소정훈(So Jung-Hun),유권종(Yu Gwon-Jong),서승직(Suh Seung-Jik) 한국태양에너지학회 2009 한국태양에너지학회 논문집 Vol.29 No.1
Photovoltaic(PV) permits the on-site production of electricity without concern for fuel supply or environmental adverse effects. The electrical power is produced without noise and little depletion of resources. So BIPV(Building-Integrated Photovoltaic) system have been increased around the world. Hereby the relative installation costs of the system will be relatively low compared to traditional installations of PV in high-rise buildings. This paper examined possibility of building integrated balcony PV system and analyzed both performance and problems of this system. The system is influenced by conditions such as irradiation, module temperature, shade and architectural component etc. IF this BIPV system of 1.1kW is possible the natural ventilation in the summer case, the temperature of PV module decrease and the the efficiency of PV system increase generally. By the results, the annual averaged PR of BIPV system of cold facade type is about 74.7%.