• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2017년도 추계학술대회
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• pp.536-538
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• 2017

나로우주센터에서는 한국형우주발사체(KSLV-II)의 이륙순간 발사체 주요부분에 대한 초고화질(UHD) 고속영상 획득 및 영상분석을 위해서 발사대 주변과 발사대 타워에 초고화질 고속 디지털카메라 시스템을 설치할 계획이다. 본 논문에서 현재 나로우주센터에서 운용중인 고속 디지털카메라 시스템의 구성과 한국형우주발사체 발사임무 수행을 위한 초고화질(UHD) 고속 디지털카메라 시스템의 구성을 비교하여 기술하였다.

• 항공우주산업기술동향
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• 제6권2호
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• pp.125-132
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• 2008

빨리 이동하는 피사체의 움직임을 상세히 분석하기 위해서는 고속 카메라가 필수 불가결하다. 본 논문에서는 고속 필름 카메라와 고속 디지털 카메라의 기본개념, 역사적 배경 및 향후 고속 카메라의 동향을 기술 하고자 한다. 또한 해외 및 국내 고속 카메라의 사용현황과 나로 우주센터에서 사용될 고속 카메라의 운용계획을 기술 하고자 한다.

• 디지털콘텐츠학회 논문지
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• 제15권3호
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• pp.425-432
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• 2014

4K 초고속 카메라 촬영은 해상도 및 셔터스피드 증가로 인해 빠른 피사체의 영상을 모션 블러 없이 Full HD 4배 해상도로 촬영이 가능하다. 그러나 해당 촬영은 데이터 량의 증가와 광량, 포커스 등 여러가지 제약사항이 뒤따른다. 증가된 셔터스피드로 인해 광량 부족 현상을 가져올 수 있어 조리개를 개방하여 촬영하는 경우가 많아 초점 조절에 제약이 따른다. 또한 증가된 해상도와 프레임레이트로 인해 저장 공간의 한계가 뒤따르기 때문에 촬영 기록에 제한이 따르고 있다. 따라서 본 연구는 4K 초고속 카메라(Phantom Flex 4K) 제작 사례를 통해 위와 같은 한계점들에 대해 분석하고, 이를 극복하기 위한 효율적인 워크플로우를 디자인 하였다.

• Journal of Biosystems Engineering
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• 제39권4호
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• pp.324-329
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• 2014

Purpose: The finite element method (FEM) is advantageous because it can save time and cost by reducing the number of samples and experiments in the effort to identify design factors. In computational problem-solving it is necessary that the exact material properties are input for achieving a reliable analysis. However, in the case of fiber boards, it is difficult to measure their cross-directional material properties because of their small thickness. In previous research studies, the Poisson's ratio was measured by analyzing ultrasonic wave velocities. Recently, the Poisson's ratio was measured using a high-speed digital camera. In this study, we measured the transverse strain of a fiber board and calculated its Poisson's ratio using a high-speed digital camera in order to apply these estimates to a FEM analysis of a fiber board, a corrugated board, and a corrugated box. Methods: Three different fiber board samples were used in a uniaxial tensile test. The longitudinal strain was measured using the Universal Testing Machine. The transverse strain was measured using an image processing method. To calculate the transverse strain, we acquired images of the fiber board before the test onset and before the fracture occurred. Acquired images were processed using the image processing program MATLAB. After the images were converted from color to binary, we calculated the width of the fiber board. Results: The calculated Poisson's ratio ranged between 0.2968-0.4425 (Machine direction, MD) and 0.1619-0.1751 (Cross machine direction, CD). Conclusions: This study demonstrates that measurement of the transverse properties of a fiber board is possible using image processing methods. Correspondingly, these processing methods could be used to measure material properties that are difficult to measure using conventional measuring methodologies that employ strain gauge extensometers.

• Journal of Welding and Joining
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• 제17권1호
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• pp.71-76
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• 1999

The real-time holographic interferometer with digital high-speed camera is applied to the experimental study of laser induced plasma/plume in pulsed Nd:YAG laser welding. A pulsed Nd:YAG laser with 1.2 kW average power is applied to generate laser induced plume. The recording speed of the high-speed camera is 3,000 f/s. The high speed photographs of weld plume without another visualization method, are compared with the visualization photographs with holographic interferometer. The radiation intensity from the laser induced plume is recorded by the high speed photographs, which fluctuated during laser radiation and disappeared after laser end. The density distribution of the plume is recorded by the holographic visualization method. The experimental results show the process of generation of the laser induced plasma/plume, and give the feasibility of quantitative measurement of laser induced plume in laser welding.

• 대한기계학회논문집A
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• 제32권11호
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• pp.943-950
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• 2008

A novel nondestructive testing (NDT) system, which is able to detect a crack with high speed and high spatial resolution, is urgently required for inspecting small cracks on express train wheels. This paper proposes a high speed scan type magnetic camera, which uses the multiple amplifying circuits and the crack indicating pulse output system. The linearly integrated Hall sensors are arrayed in parallel, and the Hall voltages from each sensor in the scanning direction are obtained and amplified. High-speed NDT can be achieved by using the exclusive analog-digital converter and micro-processor because the ${\partial}\;V_H/\;{\partial}$ x value, which provides the most important crack information, can be obtained by buffering and calculating. The effectiveness of the novel method was verified by examine using cracks on the wheel specimen model.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.371-374
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• 1995

The real-time holographic interferometer with a digital high-speed camera is applied to the visualization of transient temperature field. Collimated and diffused laser beams are used to the object beam according to the shape and transmittance of the phase object. Also, ESPI(Electronic Speckle Speckle Pattern Interferometer) technique is used to the visualization and quantitatie measurement of slow-varying temperature field. The experimental results obtained form these two techniques are discussed.

• 디지털융복합연구
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• 제12권8호
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• pp.295-302
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• 2014

3차원 공간정보를 구축하기 위해서는 고정밀의 3차원 점군데이터를 취득할 수 있는 레이저스캐닝 기술과 고해상도의 다중분광 영상정보를 취득할 수 있는 사진측량용 카메라의 활용은 필수이다. 그러나 사진측량용 카메라는 장비특성상 높은 구입비와 어려운 구입경로, 낮은 적용성으로 폭넓은 활용분야에 비해 활용성이 떨어진다. 따라서 일반사용자가 빠르고 간편하게 접근할 수 있는 디지털카메라를 이용하여 다차원 정사영상을 구축하는 기법을 연구하였다. 즉 3차원공간정보의 핵심자료인 3차원 다중분광영상정보를 구축하기 위해 디지털카메라를 개조하고 캘리브레이션 작업을 수행하였다. 스테레오 사진측량을 위한 기준점 측량과 관측대상에 대한 다중분광촬영, 정사영상으로의 변환 등을 거쳐 다차원 정사영상을 구축하였다.

• 방송과미디어
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• 제5권1호
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• pp.59-71
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• 2000

This paper presents a survey of the CMOs-based image sensor and its applications to various real field digital camera. CMOS image sensor, called active pixel sensor (APS), has many interesting properties such ash I회 sensitivity, high speed readout, random access and lower power consumption when it is compared with CCd. this paper also addresses the state-of-the-art of CMOS image sensor, and gives some examples of its application to digital camera and special-purpose cameras. with the advancement of semiconductor technology, CMOS image sensor is a future technology for imaging system, and will be widely used in the filed of image capturing for consumer electronics and scientific measurements.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3015-3020
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• 2007

An experimental study of the dynamic characteristics of the free rising oblate spherical bubble is investigated. As noted by Saffman, the characteristics of the spiral motion are defined with parameters of the spiral frequency, spiral radius, and rising velocity. High speed camera recorded every detail information of free rising bubble. The spiral number, the bubble rise velocity, and the angular velocities were measured for the bubble size between 1.0mm to 20.0mm in diameter. In order to make clear trajectory, we employed the Fast Fourier Transformation for the normal digital camera data to synchronize with the high speed camera data. It was found that the spiral number suggested here was monotonically decreased as the bubble size increases. The present observation, however tells us that previous Saffman's formulation shows a good agreement with the trend, but over estimated spiral number. Therefore, it is recommended that Saffman's theoretical study is needed to be improved.