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오늘 본 자료
도덕희(Doh D. H),황태규(Hwang T.G),조용범(Cho Y.B),백태실(Baek T. S),편용범(Pyun Y.B.) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
3D-PTV measurement was conducted on the wake of a sphere. The Reynolds number is 1130 with the diameter(d=30mm). The measurement system consisted of three CCD cameras, an image grabber, an Ar-Ion laser and a host computer. An eigenvalue analysis was introduced for the analysis on the wake. Statistical turbulent properties were quantitatively clarified using the time-consecutive instantaneous three-dimensional vectors obtained by the 3D-PTV system. The spatial distributions of the sphere wake showed strong elations with spiral motions of the vortcies shedded from the surface of the sphere.
도덕희(D.H. Doh),조효제(H.J. Jo),조경래(K.R. Cho),문경록(K.R. Moon),이재민(J.M. Lee),황태규(T.G. Hwang) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
A new 3D-PTV algorithm (a Volume PTV) based upon a hybrid fitness function has been constructed. A coherency fitness function is introduced using the information of space and time to sort out the correct particle pairs between the two camera images. The measurement system consists of two-high-definition-cameras(1k × 1k), a Nd-Yag laser and a host computer. The developed algorithm has been employed to investigate the flow features of the cylinder wake. The Reynolds numbers with the cylinder diameter (d=10㎜) are 360, 720, 900 and 1260. Two-dimensional displacements of the particles of each camera’s image and neighbouring constraints were introduced to reduce the calculation loads. More than 10,000 instantaneous 3D vectors have been obtained by the constructed algorithm. The constructed algorithm could recover more than 80~90% of the particle numbers in the image.
도덕희(Doh D.H),조효제(Jo H.J),황태규(Hwang T.G),조경래(Cho K.R),편용범(Pyeon Y.B),조용범(Cho Y.B) 한국마린엔지니어링학회 2006 한국마린엔지니어링학회 학술대회 논문집 Vol.2006 No.-
Experimental analyses on the Hrdroelastic Flow-Structure Interactions on pulsed impinged jet is measured with the FSIMS(Flow-Structure Interaction Measurement System. The nozzle diameter is D=15㎜ and two major experiments have been carried out for the cases of the distance between the nozzle tip to the elastic wall is 6.0. The pulsed jets were controlled by a solenoid valve and were impinged onto an elastic plate (material: silicon, diameter: 350㎜, thickness: 0.5㎜, hardness: 15). The Reynolds numbers were 20,000 and 24,000 when the jets were impinged with the volume velocities. The results showed that the elastic plate moved slightly to the opposite direction of the jet direction at the time of valve opening. It has been shown that the vortices travelling over the surface of the wall made the elastic wall distorted locally due to a vector forces between rotating forces of the vortex and a newly-incoming flow.
표준화상을 이용한 2차원 PIV 와 3차원 PIV 계측 및 성능비교검정
도덕희(Doh D. h),황태규(Hwang T.G),송주석(Song J. S),백태실(Baek.T.S),편용범(Pyun Y.B.) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Quantitative performance test on the conventional 2D-PLV and the hybrid hygular 3D-PIV(Stereosecpic PIV) was carried out. LES Data sets on an impinging jet which are provided on the webpage(http://www.vsj.or.jp/piv) for the PIV Standard project were used for the generation of vitual images. The generated virtual images were used for the 2D-PIV and 3D-PIV measurements. The measurement results showed that the results obtained by 2D-PIV on average values are clouser to the LES date than those those obtained by 3D-PIV, but turbulent properties obtained by 2D-PIV are largely anderestimated than those obtained by 3D-PIV.
표준영상을 이용한 스테레오 PIV와 스테레오 PTV의 성능비교
도덕희(Doh D. H.),황태규(Hwang T. G.),조용범(Cho Y. B.),편용범(Pyun Y. B.) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.4
The performances of the newly constructed Stereoscopic PTV and Stereoscopic PIV which had been completed based on a 3D-PTV principle are tested using the Standard Images. Virtual images were produced for the benchmark tests of the constructed two Stereoscopic techniques. The arrangement of the two cameras was based on angular position. The calibration of cameras and the pair-matching of the three-dimensional velocity vectors were based on Genetic Algorithm based 3D-PTV technique. The Standard data of LES are on the impinged jet proposed by VSJ. It is shown that the results obtained by Stereoscopic PTV have better reliability than those by Stereoscopic PTV.
도덕희(Doh D.H.),조용범(Cho Y.B.),편용범(Pyeon Y.B.),권순홍(S.H. Kwon),이정한(Lee J.H.),황윤식(Hwang Y.S.),류민철(Ryu M.C.) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-
The sloshing flows in the cargo tank model of a ship are measured by PIV and are analyzed with the results. The measurement system is consisted of a Nd-Yag laser(120mJ, 15㎐), two cameras(1k × 1k) and a host computer. Four experimental cases were tested for the tank model, in which swaying motions are made by 6 DOF-motion platform. The amplitudes of swaying are 9.76㎜ and 29.29㎜, and the frequencies are 0.633㎐ and 0.828㎐. The measurement regions are the vertical plane 50㎜ away from the front wall of the tank where a pump tower is installed. It was verified that the flow patterns of the sloshing are similar each other when the swaying amplitudes are similar.
도덕희(Doh D.H.),조효제(Jo H.J.),김병열(K. B.Y.),문경록(Moon K.R.),이창제(Lee C.J.) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
A simultaneous measurement system for the velocity field and the pressure field of fluid flows is constructed. The measurement system consists of a PIV system and a pressure measurement system. The pressure fields are calculated by using the velocity field obtaind by the PIV system and the reference pressure measured simultaneously at a reference point. The flow field around a rectangular bluff body square is investigated, and the characteristics between the flow fields and the pressure field near the body are discussed.
Flow Analysis around a Floating Cylinder in a Swirl Flow with a Stereoscopic-PIV
Doh D.H(도덕희),Hwang T.G(황태규),Tanaka K(다나카 코지),Takei M(타께이 마사) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
The flow characteristics around a floating cylinder in a swirling flow field in a vertical pipe with a length of 600㎜ and an inner diameter of 100mm is investigated by the use of the Stereoscopic-PIV system. The measurement system consists of two cameras, a Nd-Yag laser and a host computer. Optical sensors(LEDs) were used to detect the location of the floating cylinder and to activate the Stereoscopic-PIV system. A conditional sampling Stereoscopic-PIV system was developed in which the flow fields around the floating cylinder are measured at the events of the activations. It has been verified that the motion of the floating cylinder becomes stable when the azimuthal velocity component of the swirl flow is maintained at stable states.