http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : 조대환 (검색결과 325 건)
- 무료
- 기관 내 무료
- 유료
-
-
조대환,강태진 한국섬유공학회 1996 한국섬유공학회지 Vol.33 No.10
Objective method to evaluate the fabric wrinkle properties has been studied by using Image Analysis System and the results has been companied with the AATCC Wrinkle Recovery Replicas. The image of each replica was obtained through image capturing system, then the noise in the image was reduced using Gaussian and Median filters. The parameters which well describe the quantity of fabric wrinkle were defined, and the objective evaluation of degree of wrinkle was obtained using those parameters. The grey intensity in the grey scale image was assumed to be the relative height of fabric wrinkle. Those defined parameters are the deviation of grey intensity at each profile of horizontal scanning of grey scale image, total numbers of peak points which the wave of profile are tumid at each profile, and the numbers of peak point in fixed uniform domains. Another parameter defined was the sharpness of wrinkle crimp. In the method of projecting grid phase analysis, the uniform grid on the replica surface was made first, then the gridded image of each replica was captured, and the projecting grid phase was analyzed. The 3-D shape of the wrinkle of each replica was reconstructed with the data obtained from the deformation ratios of grid lines. Based on the reconstructed 3-D information of each replica, the degree of wrinkle in the fabric was qualltified using the parameters defined to describe the degree of wrinkle. By examining the parameters obtained for each of the five replicas at the method of grey scale image and projecting grid phase analysis, the quantified wrinkle degrees among these five standard replicas show good relationship of logarithmic function.
-
조대환 한국마린엔지니어링학회 1999 한국마린엔지니어링학회지 Vol.23 No.2
This paper is aimed to investigate behaviour of vortex in 2-D step cavity with high Reynolds numbers$(3.2{\times}10^{3},\;10^{4},\;3{\times}10^{4},\;5{\times}10^{4}\;and\;7{\times}10^{4})$. The SOLA algorithm which is MAC type was adopted to solution method computing the flow field on irregular grid. In case of $Re=7{\times}10^{4}$ flow behavior is steady bu periodic unsteady sinusoidal fluctuation of local velocity and kinetic energy is found for $Re=10^{4}$ Continuous movements of small eddies in the secondary flow regions are discov-ered for $3{\times}10^{4}$ Generation of eddies and their active migrating behavior are detected over $Re=5{\times}10^{4}$ resulting in complete unsteady and non-linear flow characteristics Furthermore a typhoon-like vortex(TLV) appears intermittently and rotates along the separation regions and boundary layers.
-
Phase Diagram에 의한 밀폐캐비티의 비정상 유동특성
조대환 한국마린엔지니어링학회 1999 한국마린엔지니어링학회지 Vol.23 No.6
In this study a phase diagram has been used to investigate the unsteadiness of two-dimensional lid-driven closed flows within a square cavity for twelve Reynolds numbers; $7.5{\times}10^3,\; 8{\times}10^3,\; 8.5{\times}10^3,\; 9{\times}10^3,\; 9.5{\times}10^3,\; 10^4,\;1.5{\times}10^4,\;2{\times}10^4,\; 3{\times}10^4,\; 7.5{\times}10^4$ and $10^5$. The results indicate that the first critical Reynolds number at which the flow unsteadiness of sinusoidal fluctuation appears from the temporal variation of total kinetic energy curves is assumed of sinusoidal fluctuation appears form the temporal variation of total kinetic energy curves is assumed to be in the neigh-bourhood of $Re=8.5{\times}10^3$ The second critical Reynolds number where the periodic amplitude and frequency collapse to random disturbance being existed around $Re=1.5{\times}10^4$ The exponentially decreasing vortices formed at the lower two corners are found commonly at the time-mean flow pattern of $Re=3{\times}10^4$.
-
입자영상유속계에 의한 기포붐의 Plume 거동특성에 관한 연구
조대환,오병주,이영호 해양환경안전학회 2000 海洋環境安全學會誌 Vol.6 No.1
Bubble boom may be a good alternative for the prevention of oil spill pollution due to its easy deployment and clean post-process tasks. The present work is focused on the experimental investigation of air bubble movement for the bubble boom by visualization and quantitative PIV measurements. Bubble plume was generated by adjusting the pressure of pressure vessel ranging 6.7 kpa to 14.7 kpa. The results showed at lower inlet velocity and higher supply air flow rate that bubble boom maintained its containing capability reasonably well up to the maximum containing limit.
-
수중 장애물의 하부틈새 크기가 하류 유동장에 미치는 영향
조대환,Cho, Dae-Hwan 해양환경안전학회 2008 해양환경안전학회지 Vol.14 No.4
해안 지역은 해수의 운동에너지의 대부분은 해안에서 소산되며 이 과정에서 해안의 토사 등이 유실된다. 수면에 돌출된 방파제에 비해 수중구조물은 해수의 유통을 가능하게 하고 해안선을 따라 해수순환을 가능케 한다. 이 연구에서는 해안 침식을 방지 기능을 갖는 수중구조물을 하부틈새를 갖는 수중장애물로 형상화 하고 후방의 흐름특성을 규명하였다. 실험은 Re =$1.2{\times}10^4$ 조건에서 2프레임 입자영상유속계를 이용하여 속도장을 계측하여 고찰하였다. 측정된 시간평균 속도분포를 분석한 결과 유선의 곡률 효과가 현저히 나타났으며 전단층 주위 유체의 유입 등의 영향으로 박리 전단층 내에서 커다란 와구조가 연속적으로 발생하였다. 또한 하부틈새의 크기가 증가할수록 재순환 영역의 중심이 후류로 이동하고 재순환영역의 강도도 약해지는 결과를 보였다. The coastal zone is a delicate and dynamic area in which the majority of a water kinetic energy is dissipated. These processes are subsequent to the transport of the beach materials. In comparison to emerged breakwaters, submerged structures permit the passage of some wave energy and in turn allow for circulation along the shoreline zone. This research aims to examine the beach erosion prevention capability of submerged structure by laboratory model. The flow characteristics behind a submerged obstacle with bottom gap were experimentally investigated at Re = $1.2{\times}10^4$ using the two-frame PIV(CACTUS 2000) system. Streamline curvature field behind the obstacle has been obtained by using the data of time-averaged mean velocity information. And the large eddy structure in the separated shear layer seems to have signification influence on the development of the separated shear layer. As bottom gap size increases, the recirculation occurring behind the obstacle moves toward downstream and its strength is weakened.
-
-
-
-
조대환,최민선 목포해양대학교 2006 論文集 Vol.14 No.-
디퓨져는 흐름의 속도가 감소하면서 운동에너지가 압력으로 전환되는 배관설비이다. 광각디퓨져에서 유동단면적의 급속한 증가는 디퓨져 벽면의 박리와 역류영역 형성의 원인이 된다. 이 연구에서는 안내댐퍼가 설치된 광각 디퓨져의 흐름특성을 세 종류의 경사각(a=7。 , 10.5。 및 14。 )에 대해 조사하였다. 그 결과 안내댐퍼가 광각 디퓨져의 성능을 향상할 수 있는 유효한 방법으로 사용될 수 있으며, 경사각 a=10.5º의 경우가 가장 유수함을 보였다. Diffusers are ducts that convert flow kinetic energy to pressure by decelerating the flow. In wide angle diffuser, the increasement of cross-sectional area so rapidly cause possibly separate from the diffuser wall and forming areas of backflow. The flow characteristics of wide angle diffuser with guide damper was investigated for three kind of inclined angle( a=7。 , 10.5。 and 14。 )of guide damper. Judging from the results, guide damper can be used as an effective means of improvement for diffuser performance and inclined angle of a=10.5ºwas through to be the best among three cases.
DBpia연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
