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임대현(Dae-hyun Yim),김국배(Guk Bae Kim),김도일(Do-Il Kim),이형구(Hyong-Koo Lee),이상준(Sang Joon Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
A new medical X-ray PIV technique was developed using a conventional medical X-ray tube. To acquire images of micro-scale particles, the X-ray PIV system consists of an x-ray CCD camera with high spatial resolution, and a X-ray tube with small a focal spot. A new X-ray exposure control device was developed using a rotating disc shutter to make double pulses which are essential for PIV application. Synchronization methodology was also developed to apply the PIV technique to a conventional medical X-ray tube. In order to check the performance and usefulness of the developed X-ray PIV technique,it was applied to a glycerin flow in an opaque silicon tube. Tungsten particles which have high X-ray absorption coefficient were used as tracer particles. Through this preliminary test, the spatial resolution was found to be higher than ultrafast MRI techniques, and the temporal resolution was higher than conventional X-ray PIV techniques. By improving its performance further and developing more suitable tracers, this medical X-ray PIV technique will have strong potential in the fields of medical imaging or nondestructive inspection as well as diagnosis of practical thermo-fluid flows.
강종훈(Jong Hoon Kang),임대현(Dae Hyun Yim),이상준(Sang Joon Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
In this study, the threshold wind speed that causes physical damage on Kiwi fruit plant was investigated through wind tunnel experiments. Total 30 samples of Kiwi fruit branches were tested. On average, the wind speeds for tearing leaves and breaking side branch from the main branch were about 20㎧ and 21.7㎧, respectively. For the cases of broken branches, the average length and diameter of the branches were 587.5㎜ and 7.2㎜, respectively. The discoloration and dehydration of Kiwi plant were also observed by photographing leaves and branches after 24 hour later of the wind damage. In addition, the shelter effect of porous wind fences which have been used at agricultural districts was examined with varying several parameters.
X선관을 이용한 불투명한 물체 내부 유동의 정량적 가시화 연구
김국배(Guk Bae Kim),임남윤(Nam Yun Lim),류재춘(Jae Chun Ryu),임대현(Dae Hyun Yim),이형구(Hyung Koo Lee),이상준(Sang Joon Lee) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
To diagnose circulatory diseases in the viewpoint of hemodynamics, we need to get quantitative hemodynamic information of blood flows related with the vascular diseases with high spatial resolution of tens micrometer and high temporal resolution in the order of millisecond. For investigating in-vivo hemodynamic phenomena, a new diagnosing technique combining medical radiography and PIV method was newly proposed and developed. This angiographic PIV technique consists of a medical X-ray tube, an X-ray CCD camera, a shutter module for double pulses of X-ray, and a synchronizer. The feasibility of the angiographic PIV technique was tested and quantitative flow velocity field distribution of a flow inside an opaque conduit was acquired by the developed system. It can be used for measuring flow phenomena of nontransparent fluids inside opaque conduits.