• 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.

• 로봇학회논문지
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• 제5권2호
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• pp.85-92
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• 2010

In this paper, we propose a digital image stabilization technique using edge detection and Lucas-Kanade optical flow in order to minimize the motion of the shaken image. The accuracy of motion estimation based on block matching technique depends on the size of search window, which results in long calculation time. Therefore it is not applicable to real-time system. In addition, since the size of vector depends on that of block, it is difficult to estimate the motion which is bigger than the block size. The proposed method extracts the trust region using edge detection, to estimate the motion of some critical points in trust region based on Lucas-Kanade optical flow algorithm. The experimental results show that the proposed method stabilizes the shaking of motion image effectively in real time.

• 국제초고층학회논문집
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• 제2권2호
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• pp.105-113
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• 2013

Recent studies proved turbulent flow properties in high-rise building models differ from those in low-rise building models by comparing turbulent statistics. Although it is important to understand the flow characteristics within and above high-rise building models in the study of urban environment, it is still unknown and under investigation. For this reason, we performed wind tunnel experiment using Particle Image Velocimetry (PIV) to investigate and identify the turbulent flow properties and characteristic flow patterns in high-rise building models. In particular, we focus on instantaneous flow field near the canopy and extracted flow field when homogeneous flow field were observed. As a result, six characteristic flow patterns were identified and the relationship between these flow patterns and turbulent organized structure were shown.

• 디지털융복합연구
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• 제16권4호
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• pp.313-319
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• 2018

본 연구는 최근 방송, 영화 등에 활발하게 사용되고 있는 드론의 무빙 영상이 수용자의 몰입도와 흥미 유발, 감정상태 등에 미치는 영향을 살펴본 실험 연구이다. 그동안 미디어 영상 효과 연구들은 영상의 움직임이 스토리 자체에 내재되어 있는 느낌을 주기 위해서 카메라의 움직임을 자제하는 것이 좋으며, 카메라의 움직임이 오히려 수용자의 자연스러운 시청에 방해가 될 수 있다고 주장하고 있다. 본 연구에서는 드론의 움직이는 영상이 시청자의 몰입도, 흥미 유발, 감정 상태 등에 어떤 영향을 미치는지 알아보기 위해서, 대학생들을 두 그룹으로 나누고, 한 그룹의 피실험자들에게는 무빙 중심으로 편집된 드론 영상물을 보여주고, 다른 한 그룹의 피실험자들에게는 호버링 중심으로 편집된 드론 영상물을 각각 보여준 다음, 설문조사를 통해 이들이 느낀 몰입도, 흥미도, 감정상태 등을 측정하고, 측정한 결과를 변량 분석하였다. 분석 결과, 드론의 움직임이 있는 영상물을 감상한 피실험자들은 드론의 움직임이 없는 영상물을 감상한 피실험자들에 비해, 흥미를 더 많이 느끼고, 긍정적인 감정상태를 더 많이 느낀것으로 나타났다. 그러나 드론의 무빙과 피실험자들의 몰입도 간에는 서로 관련이 없는 것으로 나타났다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.509-515
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• 2001

In a square cavity, the flow phenomena in the surrounding of the bubble attached at the upper cooled solid wall were studied by using a thermo-sensitive liquid-crystal tracer and image processing techniques. This method offers the advantage of measuring the entire flow field in a selected plane within the fluid at a given instant of time in contrast to point by point method like T/C. Quantitative data of the temperature were obtained by applying a colour-image-processing to the. visualized image. As the growing of a bubble, In a bubble size appears the flow phenomena which the direction of flow is reversed in the entire temperature and flow field. The observed phenomena are described with regard to thermocapillary convection.

• 대한기계학회논문집B
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• 제25권12호
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• pp.1879-1886
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• 2001

n a enclosed square cavity occurred B nard convection, the flow phenomena in the surrounding of the bubble attached at the upper cooled solid wall were studied by using a thermo-sensitive liquid-crystal tracer and image processing techniques. This method offers the advantage of measuring the entire flow field in a selected plane within the fluid at a given instant of time in contrast to point by point method like T/C. Quantitative data of the temperature were obtained by applying a colour-image-processing to the visualized image. As the flowing in a bubble, In a bubble size appears the flow phenomena which the direction of flow is reversed in the entire temperature and flow field. The observed phenomena are described with regard to the thermocapillary convection.

• 설비공학논문집
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• 제17권2호
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• pp.110-116
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• 2005

This paper deals with interaction between two bubbles or particles and flow around them, visualized by a moving object flow image analyzer(MOFIA) consisting of a three-dimensional (3D) moving object image analyzer(MOIA) and two-dimensional particle image velocimetry(PIV). The experiments were carried out for rising bubbles or particles of various densities, sizes, and/or shapes in stagnant water in a vertical pipe. In the MOFIA employed, 3D-MOIA was used to measure particles or bubbles motion and PIV was used to measure fluid flow, The experimental results showed that the interaction was characterized by the shape, size and density of two particles or bubbles.

• 한국통신학회논문지
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• 제11권1호
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• pp.1-15
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• 1986

Optic flow는 이동물체표면의 3차원 속도를 영상판(image plane)에 투영시킨 2차원 속도이다. 본 논문은 이 동물체의 연속영상으로부터 optic flow 를 구하는 기술들을 조사분석하고 정해진 optic flow로부터 물체의 인식 및 3차원 속도를 결정하는 기술들을 논하였다. 연속영상으로부터 구해진 optic flow는 영상압축기술인 영상간 부호(inter-frame image coding)에 해당되며 컴퓨터비젼 시스템(computer vision system)에서 이동물체 인식에 사용된다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.372-374
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• 2003

The optical flow theory can be utilized for automatically tracking and positioning homologous points in digital video (DV) image sequences. In this paper, the Lucas-Kanade optical flow estimation (LKOFE) method and the normalized cross-correlation (NCC) method are compared and analyzed using the DV image sequences acquired by our SONY DCRPC115 DV camera. Thus, an improved optical flow estimation procedure, called 'Iterated Optical Flow Estimation (IOFE)', is presented. Our test results show that the trackable range of 3${\sim}$4 pixels in the LKOFE procedure can be apparently enlarged to 30 pixels in the IOFE.

• International Journal of Concrete Structures and Materials
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• 제9권4호
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• pp.427-438
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• 2015

The present work proposes a new image analysis method for the evaluation of the multi-walled carbon nanotube (MWNT) distribution in a cement matrix. In this method, white cement was used instead of ordinary Portland cement with MWNT in an effort to differentiate MWNT from the cement matrix. In addition, MWNT-embedded cement composites were fabricated under different flows of fresh composite mixtures, incorporating a constant MWNT content (0.6 wt%) to verify correlation between the MWNT distribution and flow. The image analysis demonstrated that the MWNT distribution was significantly enhanced in the composites fabricated under a low flow condition, and DC conductivity results revealed the dramatic increase in the conductivity of the composites fabricated under the same condition, which supported the image analysis results. The composites were also prepared under the low flow condition (114 mm < flow < 126 mm), incorporating various MWNT contents. The image analysis of the composites revealed an increase in the planar occupation ratio of MWNT, and DC conductivity results exhibited dramatic increase in the conductivity (percolation phenomena) as the MWNT content increased. The image analysis and DC conductivity results indicated that fabrication of the composites under the low flow condition was an effective way to enhance the MWNT distribution.