• 건축사
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• 통권639호
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• pp.26-27
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• 2022

• 대한토목학회논문집
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• 제4권1호
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• pp.137-144
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• 1984

경사사진(傾斜寫眞)은 수직사진(垂直寫眞)에 비해 촬영면적(撮影面積)이 넓고 접근하기 어려운 대상물(對象物)의 측정(測定)이 가능한 장점이 있는 반면, 판독을 위한 수직화(垂直化)과정이 복잡하다. 광학적(光學的)으로는 편위수정기(偏位修正機)를 사용해서 경사사진(傾斜寫眞)을 수직사진화상(垂直寫眞畵像)으로 얻을 수 있지만 경사각(傾斜角)이 큰 경우에는 광학적(光學的)인 처리(處理)가 불가능하다. 이에 본(本) 연구(硏究)는 광학적(光學的)으로 처리(處理)가 어렵고 정도(精度)가 낮은 편위수정(偏位修正)을 해석적(解釋的) 방법(方法)으로 해석(解析)함으로써 경사사진(傾斜寫眞)에 의한 시설물의 좌표해석(座標解析)의 한 기법(技法)을 제시하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.688-694
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• 2002

As a tool for strain measurement to work with screw driven or hydraulic material test systems, in which mechanical vibration is inherent, SSDG(Speckle Strain/Displacement Gage), ESP(Electronic Speckle Photography) and its 3-dimension version SDSP are investigated for the theory and practical appliance. Through tension test of steel strips, their validity and shortcomings are examined. As the results, it has been shown that, although SSDG and ESP provide direct measurement of in-plane strain in one direction, they are so sensitive to the out-plane displacement. On the other hand, SDSP which is aided with DIC (Digital Image Correlation) technique to trace the movement of the speckles provides not only in-plane 2-dimensional displacement field, but also out-of-plane displacement simultaneously. However, because the DIC is time-consuming, not automated yet and it needs post-processing to evaluate strain from the displacement field, SDSP appears to be not adequate as a real time sensor.

• 한국인쇄학회지
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• 제12권1호
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• pp.1.2-15
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• 1994

This is the study which appear the relation between the situation of Anchor point and the qualities of lithographic prints using the uncoated paper. Anchor point were measured by microscopic photography and Kubelka-munk`s method. The situation of Anchor point increased with print density and print though, but it decreased with evenness and rub off. In case of commercial uncoated paper, the situation of Anchor point was optimized when it was 25~35% apporoximately. In preparation of samples for microscopic photography, the samples were used by the resin testing methods. This method used that the resin fixes the printed papers of sample very hard, in preparation of samples for microscopica potography a good result could be gained by this method.

• 한국자동차공학회논문집
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• 제4권2호
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• pp.147-157
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• 1996

Natural gas is gaining more attraction as a future fuel in particular both for environmental protection and energy conservation. In order to bring about more widespread use of gaseous engines, the technology capable of achieving output and efficiency performance equivalent to that of diesel engines needs to be developed. In the present paper, the requirements of the pilot torch from pre-chamber for ensuring ignition and promoting combustion are discussed by means of taking high-speed flame photography and system can run with leaner mixture of various fuels comparing to the electric plug ignition system cause the ignition delay period ignited with the torch and the combustion period are very short in spite of changing A/F of gaseous fuels in the main chamber. However, the suitable piston-cavity design for the use of lower-hydrocarbon fuels such as propane and butane must be discussed increasingly in the mear future.

• 한국자동차공학회논문집
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• 제15권5호
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• pp.24-29
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• 2007

This study aims to provide a fundamental data for directly injected hydrogen fuel engines. Spray, ignition and combustion characteristics of hydrogen were studied using constant volume chamber. For spray visualization, hydrogen was vertically injected into a combustion chamber at various condition, for example, injection pressure, ambient pressure. And an argon laser was used for the shadowgraph photography by applying optical method. Also, to investigate heat-release rate and flame propagations, spark was ignited on hydrogen injected at the different time after injection and the duration of injection was also changed. Processes of ignition and combustion were analyzed by heat-release rate calculated by pressure history and were observed by shadowgraph photography The results gave much knowledge of spray, ignition and combustion characteristics of hydrogen.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2002년도 제24회 KOSCO SYMPOSIUM 논문집
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• pp.61-67
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• 2002

Characteristics of lifted flames in axisymmetric laminar coflow jets have been investigated experimentally. Approximate equations for velocity and concentration with virtual origins have been proposed to analyze the behavior of flames in coflow jets. Measuring Rayleigh intensity to investigate the concentration field. proposed approximate equations were confirmed. By using the results of OH PLIF, direct photography and Rayleigh scattering measurement, it is shown that the locations of maximum intensity in direct photography coincide with the tribrachial points in axisymmetric jets and the tribrachial points travel on the stoichiometric contour. For coflow jets, the experimental results of liftoff height have been successfully correlated with nozzle exit velocity using predicted behavior from proposed approximated equations. These results substantiate the stabilization mechanism in coflow jet is based on the balance between flame propagation speed and axial flow velocity, same as for the free jets.

• 복식문화연구
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• 제5권1호
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• pp.151-164
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• 1997

This study pursues the problems of plan photogrammetry which is widely used in somatotyping at present, and find out a method which can improve accuracy of measurement on the basis of principles and mechanisms of photography-the basic foundation of the photographic analysis methods. As a result, this study proposes a new method which is based on the reference point method and perspective coordinate system. And the test measurement was operated to compare the measurement accuracy of the proposed method and the method based on reference grid screen method and perpendicular coordinate system which is commonly used at present. The result of this test measurement showed that the proposed method has higher accuracy. Two reasons can be pointed out for the improvement of measuring accuracy. The first reason is that the proposed perspective coordinate system reduces the perspective distortion of photography. And second reason is that measuring points can be closely placed to the scale and coordinate reference plan of measurement by the proposed reference point method which make possible to place measuring object (or person) at the center of scale and coordinate reference plan by utilizing reference points of measurement in the three dimensional space not on screen.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2003년도 International Meeting on Information Display
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• pp.1034-1037
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• 2003

In this work, Integral photography with variable focusing lens arrays is proposed. We fabricate two-dimensional liquid crystal lens arrays using cohesion of UV curable polymer and lithography. Applied voltage to the cell alters the effective refractive index of the liquid crystal layer and results in a change of the focal length. By adjusting the focal length, synchronized elemental image array for real or virtual mode is integrated in front of or behind the lens array.

• 한국정밀공학회지
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• 제21권10호
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• pp.154-161
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• 2004

An experimental method for measuring side-necking deformation near a crack-tip is described. It is based on Stereoscopic Digital Speckle Photography and Digital Image Correlation, and it is simple and robust to mechanical vibration inherent to a hydraulic material test system. The validity and accuracy are evaluated through a calibration fur rigid body translation. A case study has been performed for a CT specimen made of a ductile steel and the three dimensional profiles of the side-necked region are presented as the load increases. Also, the details of the procedure and the surface treatment are discussed.