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RISS 인기검색어
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- 저자 : 임희창(Lim, hee chang) (검색결과 116 건)
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O-ring을 이용한 원주의 항력감소에 관한 실험적 연구
임희창,이상준,Lim, Hee-Chang,Lee, Sang-Joon 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.8
The flow around a circular cylinder was controlled by attaching O-rings to reduce drag force acting on the cylinder. Four experimental models were tested in this study; one smooth cylinder of diameter D (D=60mm) and three cylinders fitted with O-rings of diameters d=0.0167 D, 0.05D and 0.067 D with pitches of PPD=2D, 1D, 0.5D and 0.25D. The drag force, mean velocity and turbulence Intensity profiles in the near wake behind the cylinders were measured for Reynolds numbers based on the cylinder diameter in the range of Re$_{D}$=7.8$\times$10$^3$~1.2$\times$10$^{5}$ . At Re$_{D}$=1.2$\times$10$^{5}$ , the cylinder fitted with O-rings of d=0.0167D in a pitch interval of 0.25D shows the maximum drag reduction of about 5.4%, compared that with the smooth cylinder. The drag reduction effect of O-rings of d=0.067D is not so high. For O-ring circulars, as the Reynolds number increases, the peak location of turbulence intensity shifts downstream and the peak magnitude is decreased. Flow field around the cylinders was visualized using a smoke-wire technique to see the flow structure qualitatively. The size of vortices and vortex formation region formed behind the O-ring cylinders are smaller, compared with the smooth cylinder.der.
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Orifice shape effect of the TLCD system under a low frequency
임희창,Lim, HeeChang The Korean Society of Visualization 2014 한국가시화정보학회지 Vol.12 No.1
Bluff bodies under the external periodic force vibrate at their own natural or forced frequency. Rectangular bodies or similar structures such as high-rise towers and apartments, and recently a well-cited application - offshore floating bodies, usually needs to reduce these vibrations for stability and the mode control. Therefore, this study is aiming to reduce or control the vibration of a structure by a passive control method, i.e., TLCD (Tuned Liquid Column Damper). Controlling a moving body with a TLCD based on a variety of the orifice shape has been preliminary studied. In order to get a proper control, an optimized study is made on the design of the orifice shape, which has internal plates with the holes. The results show the force acting on the body due to the periodic movement highly depends on the number of holes on the plate and the height of the water level. Therefore, the optimum shape of the orifice and the height of the water level should be confirmed by a series of experiments.
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미래 풍력발전산업의 집적지육성을 위한 녹산클러스터 발전방향
임희창,한규택,장광호,진성호,김용환,Lim, Hee-Chang,Han, Gyu-Taek,Jang, Gwang-Ho,Jin, Seong-Ho,Kim, Yong-Hwan 산업클러스터학회 2009 산업클러스터 Vol.3 No.1
Wind power is the most rapidly growing energy source in the world. Increased focus on climate changes and renewable energy is supporting the wind power industry in gaining momentum. Noksan wind cluster in Busan has been a major area in manufacturing the elementary parts of wind turbine. Despite growing recognition of the significance of Noksan, there has been only limited attention paid and in recent years. This paper reviews the literature of the current burning issues in wind turbine industries in the western countries. In addition, it describes the present state of Noksan wind power generation cluster and suggests the future plans to make it more effective complex.
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임희창(H.C. Lim),고민석(M.S. Koh),이상준(S.J. Lee) 대한기계학회 2001 대한기계학회 춘추학술대회 Vol.2001 No.9
Air ventilation in workplaces, whether resulting from a forced ventilation or naturally occurring airflow, has a significant impact on occupational health. In a huge steel-making factory building, typical harmful factors such as fume or dusts from hot steel-making process give unpleasant feeling. In the present study, the fume, dusts and heat released from a hot steel-making furnace were investigated experimentally. Three different kinds of canopy hoods were tested in this study. The existing model has four sides of rectilinear shape. The modified model 1 and 2 has curved and longer sides than the existing model, respectively. The effects of shape and location of the canopy hood on the local ventilation flow above the furnace. Flow visualization experiments inside the 1/100 scale-down steel-making factory model were carried out using a smoke tube method. Smoke chamber is connected with smoke generator and heat source. The modified hoods improve the local forced ventilation flow with increasing the suction speed and decreasing the vertical distance compared with present hood.
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