• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 춘계학술대회 논문집
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• pp.35-40
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• 2005

선박의 조종운동은 선체와 프로펠러 그리고 타의 연성 운동의 결과로서 선박 조종성능을 향상시키기 위해서는 각 요소의 적절한 평가 및 보완이 필요하다. 본 연구에서는 조종성능 향상 기법의 일례로 특수타의 일종인 플랩타 주위의 유동특성을 유동가시화 시험기법과 PIV 해석을 이용하여 알아본다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.13-18
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• 1998

The practical use of the particle image velocimetry(PIV), a whole-field velocity measurement method, requires the use of fast, reliable, computer-based methods for tracking velocity vectors. The full search block matching, the most widely studied and applied technique both in area of PIV and Image Coding and Compression, is computationally costly. Many less expensive alternatives have been proposed mostly in the area of Image Coding and Compression. Among others, TSS, NTSS, HPM are introduced for the past PIV analysis, and found to be successful. But, these algorithms are based on small dynamic range, 7 pixels/frame in maximum displacement. To analyze the images with large displacement, Even and Odd field image separation and a simple version of multi-resolution hierarchical procedures are introduced in this paper. Comparison with other algorithms are summarized. A Results of application to the turbulent backward step flow shows the improvement of new algorithm.

• 대한기계학회논문집B
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• 제28권9호
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• pp.1015-1021
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• 2004

Micro-resolution Particle Image Velocimetry(Micro-PIV) was used to measure the flow in a micro-branch(Micro-Bypass). In this paper, effects of particle lump at the tip of a Micro-branch and difficulties of Micro-PIV measurements for microfluidics with branch passage were described. Micro-bypass was composed of a straight channel(200(100)${\mu}$m width ${\times}$ 80${\mu}$m height) and two branches which has 100(50)${\mu}$m width ${\times}$ 80${\mu}$m height. One of branches was straight and the other was curved. Experiments were performed at three regions along streamwise direction(entrance, middle and exit of branch) and five planes along vertical direction (0, ${\pm}$10, ${\pm}$20 ${\mu}$m) for the range of Re=0.24, 1.2, 2.4. Numerical simulation was done to compare with the measurements and understand the effects of particle lump at the tip of branch. And another fluid(3% poly vinyl Alcohol aqueous solution) were adapted for this study, so there were no particle sticking. In this case, we could get velocity difference between straight and curved branches.

• Journal of Advanced Marine Engineering and Technology
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• 제28권1호
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• pp.152-161
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• 2004

The thermal load is a very important problem to be solved in many industrial systems including the electronic equipment. Impinging Jets have been known to provide a large heat transfer rates on surface for many years. The turbulence enhancement of fluid flow is requested for the efficiency elevation of heat transfer. A study on flow fields by rods attached to the wall surface as a promoter of turbulence enhancement has been carried out. The exact analysis on chracteristics of impinging jet field is requested to obtain the optimum design of the impinging jet system. By visualizing the flow field and processing the high digital image by computer PIV can afford exact data on the velocity vector kinetic energy and turbulence intensity in the complex turbulence field. In this study. three kinds of rod shape such as square. triangle. and semicircle are selected as the turbulence promoter. Nozzle diameters are 10mm. 17mm. and 23mm. And the analysis of the flow characteristics due to the above rods is carried out at Re No. 2.000, 3.000. and 4,000 by PIV measurement. It is clarified that the rod setup is very useful to obtain the turbulence enhancement and the turbulence intensity according to the shapes of rod appears large in order of the shapes of rod such as square 〉 triangle 〉semicircle.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2006년도 추계학술발표회
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• pp.53-58
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• 2006

연안 해안공학의 발달과 더불어 경제적이고 설치가 용이하며, 해수 정온화를 고려한 부유식소파제에 대한 관심이 점차 늘어나고 있다. 본 연구는 와류방식에 의한 파랑제어로 쓰이는 이흘수판이 부착된 부소파제 주위에서 생성되는 박리현상, 와의 생성과 소멸, 플래핑 (flapping) 현상 등 이흘수판을 부착함으로서 생성되는 유동장에 대해 기계공학 및 유체역학 분야에서 각광을 받고 있는 입자영상유속계 (PIV, Particle Image Velocimetry: 이하 " PIV"로 표기)를 이용하여 순간속도장, 시간평균속도장, 등속도 분포 등을 구하여 이흘수판형 부소 파제 주변의 유동을 해석하였다.

• 한국해양공학회지
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• 제10권3호
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• pp.89-95
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• 1996

The flow field around four cylinders for various angles was investigated utilizing particle image velocimetry(PIV) technique. Flow field was recorded by video camera first. Then application of PIV technique was done to the flow field. The results turned out to be useful to analyze complex flow field around multiple cylinders.

• Journal of Advanced Marine Engineering and Technology
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• 제25권4호
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• pp.898-903
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• 2001

The particle image velocimetry with liquid crystal tracers is used for visualizing and analysis of the bubbly flow in a vertical temperature gradient. This method allows simultaneous measurement of velocity and temperature field at a given instant of time Quantitative data of velocity were obtained by applying the MQD technique to visualized image. The paper describes the method, and presents the transient velocity patterns of bubbly flow.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.536-541
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• 2001

A high resolution digital cinematic Particle Image Velocimetry(PIV) has been developed. The system consists of a high speed CCD camera, a continuous Ar-ion laser and a computer with camera controller. To improve the spatial resolution, we adopt a Recursive Technique for velocity interrogation. At first, we obtain a velocity vector for a larger interrogation window size based on the conventional two-frame cross-correlation PIV analysis using the FFT algorithm. Based on the knowing velocity information, more spatially resolved velocity vectors are obtained in the next iteration step with smaller interrogation windows. The correct velocity vector at the first step is found to be critical, so we apply a Multiple Correlation Validation(MCV) technique in order to decrease the spurious vectors. The MCV technique turns out to improve SNR(Signal to Noise Ratio) of the correlation table. The developed cinematic PIV method has been applied to the measurement of the unsteady flow characteristics of a Rushton turbine mixer. A total of 3,245 instantaneous velocity vectors were successfully obtained with 4 ms time resolution. The acquired spatial resolution corresponds the performance of the conventional high resolution digital PIV system using a $1K{\times}1K$ CCD camera.

• 한국지반신소재학회논문집
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• 제17권3호
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• pp.33-46
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• 2018

본 논문에서는 대심도 굴착시 흙막이 벽체에 대한 실내 모형실험 결과를 다루었다. 지반의 지하수위와 벽체의 강성등의 영향인자가 흙막이 벽체 및 지반 거동에 미치는 영향에 대한 정성적 고찰을 위하여 기존 CIP 벽체와 CS-H벽체의 휨강성에 따른 상사법칙을 적용하여 제작 및 사용하여 모형실험을 수행하였으며, 실제 현장을 모사하여 버팀보 설치 및 굴착을 진행하였다. 또한 벽체, 지반 거동 분석을 위하여 PIV 분석을 수행하였으며, 벽체변위, 지반침하 및 지반 수평변위를 분석하여 지하수위가 높아질수록 벽체 강성이 작아질수록 변위가 커지는 것을 확인하였다.

• 한국가시화정보학회지
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• 제3권2호
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• pp.71-78
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• 2005

Uncertainty introduced by a cross-correlation algorithm based on FFT has been investigated using PIV standard images. The standard images were generated by the Monte Carlo simulation method. Both bias and random errors from the velocity vector have been analyzed with regard to the particle diameter, displacement, and the number of particles. The uncertainty of velocity is evaluated based upon the IS0/IEC standard. As a result, a total error of $0.26\%$ is included in the PIV cross-correlation algorithm. In addition, the uncertainty budget is presented, where the effect of the above three variables is examined. According to the budget, the variation of the number of particles within the interrogation window mainly contributes to the combined standard uncertainty of the real measured velocity field when excluding the effect of errors by the experiments itself. Finally, the expanded uncertainty is found to be about $12\%$ at the $95\%$ confidence level.