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다공성 방풍벽 뒤에 놓인 삼각 프리즘 주위 유동의 PTV 속도장 측정
김형범,이상준,Kim, Hyeong-Beom,Lee, Sang-Jun 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.5
The shelter effect of a porous wind fence on a triangular prism was experimentally investigated in a circulating water channel. A porous fence of porosity .epsilon.=38.5% was installed in front of the prism model. The fence and prism model were embedded in a turbulent boundary layer. The instantaneous velocity fields around the fence and prism model were measured by using the instantaneous velocity fields around the fence and prism model were measured by using the 2-frame PTV(Particle Tracking Velocimetry) system. By installing the fence in front of the prism, the recirculation flow region decreases compared with that of no fence case. The porous fence also decreases the mean velocity, turbulent intensity and turbulent kinetic energy around the prism. Especially, at the top of the prism, the turbulent kinetic energy is about half of that without the fence.
다공성 방풍벽의 다공도가 펜스후류 속도장에 미치는 영향에 관한 연구
김형범,이상준,Kim, Hyeong-Beom,Lee, Sang-Jun 대한기계학회 1998 大韓機械學會論文集B Vol.22 No.7
Velocity fields of near turbulent was behind a porous wind fence were measured using the 2-frame PTV method in a circulating water channel. The fences used in this study had different geometric porosity(.epsilon.) of 0, 20, 40 and 65%. The fence was embedded in a thin laminar boundary layer, i.e., .delta./H ~ = 0.1. Reynolds number based on the fence height H and free stream velocity(U$\_$o/) was about 8,400. As a result, a recirculating flow region was formed behind the fence for the .epsilon.=0% and 20% wind fence. For the wind fences having porosity larger than .epsilon.=40%, it was difficult to see separation bubbles behind the fence. The .epsilon.=20% porous fence reveals the maximum velocity reduction, however, the turbulent intensity and Reynolds shear stress are much greater than those of .epsilon.=40% fence. Among the wind fence tested in this study, the porous wind fence of .epsilon.=40% porosity is the most effective for abating wind erosion.
분야별로 분류된 콘텐츠를 제공하는 어플리케이션의 설계와 구현
김상형 ( Sang-hyeong Kim ),김형범 ( Hyeong-beom Kim ),순펑 ( Soon Peong ),주하정 ( Ha-jeong Joo ),박은주 ( Eun-ju Park ),임한규 ( Han-kyu Lim ) 한국정보처리학회 2017 한국정보처리학회 학술대회논문집 Vol.24 No.1
컴퓨터나 모바일 기기 사용자들이 필요한 자료나 정보 등을 검색하거나 콘텐츠가 있는 웹사이트를 찾는 경우, 흔히 사용하는 검색만으로는 어려움을 겪을 때가 존재한다. 이에 본 논문은 이러한 불편함을 최소화하기 위해 스마트폰 이용자가 원하는 콘텐츠를 찾고자 하는 경우, 분야별로 중요한 사이트들을 모아 해당 콘텐츠가 있는 사이트를 리스트로 제공해주는 어플리케이션을 개발하였다. 이는 사용자들에게 원하는 콘텐츠가 있는 사이트를 좀 더 쉽게 찾을 수 있도록 편리성을 줄 것이라 기대한다.
나선형의 표면돌출물이 부착된 원주의 근접후류에 관한 실험적 연구
권기정,김형범,Gwon, Gi-Jeong,Kim, Hyeong-Beom 대한기계학회 1996 大韓機械學會論文集B Vol.20 No.8
Surface protrusions have been attached on a cylinder surface to reduce the flow-induced structural vibration by controlling the wake flow. Wind tunnel tests on the near wake of a circular cylinder with surface protrusions were carried out to investigate the flow characteristics of the controlled wake. Three experimental models were used in this experiment; one plain cylinder of diameter D and two cylinders wrapped helically by three small wires of diameter d=0.075D with pitches of 5D and 10D, respectively. Free stream velocity was ranged to have Reynolds number from 5000 to 50,000. Streamwise and vertical velocity components of the wake were measured by a hot-wire anemometry. The spanwise velocity component measured by a one-component fiber optic LDV revealed that time-averaged wake field has a nearly two-dimensional structure. It was found that the surface protrusions elongate the vortex formation region, which decrease the vortex shedding frequency. The suppression of vortices caused by the surface protrusions increases the velocity deficit in the center of wake region.