• Korean Journal of Geomatics
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• 제3권1호
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• pp.43-51
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• 2003

This paper presents the benefits of using close-range digital photogrammetric techniques for measuring the roughness of rock surfaces, using digital stereo images obtained from a Rolleiflex 6006 metric camera. To precisely measure surface roughness, we researched on how to use the flat and curved reference surface obtained from geometrically corrected digital images of the rock surface by using the least squares method. To test the precision of the proposed technique, the surface roughness has been measured between the reference surface and sample areas of very smooth-surfaced rock. Then the results were compared with the measurements obtained from a laser sensor profilometer.

• 한국유체기계학회 논문집
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• 제6권3호
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• pp.15-20
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• 2003

For measuring friction factor of artificially-roughened surfaces which are usually applied to damper seals, flat plate test apparatus is designed and fabricated. The measurements of leakage flow and pressure distribution through round-hole patterned specimen with different hole areas are described, and a method is discussed for determining the friction factor experimentally. Results show that the friction factor of the round-hole patterned surface is bigger than that of smooth surface, and increases as increasing the hole area. A empirical friction factor model for the round-hole patterned surface can be descrived by the Moody's friction factor formula.

• Tribology and Lubricants
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• 제17권3호
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• pp.191-197
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• 2001

Nano adhesion and friction characteristics between SPM(scanning electron microscope) tips and flat plates of different materials were experimentally studied. Tests were performed to measure adhesion and friction in AFM(atomic force microscope) and LFM(lateral force microscope) modes in different conditions of relative humidity. Three different Si$_3$N$_4$ tips (rdaii : 15nm, 22nm and 50 nm) and three different flat plates of Si-wafer(100), W-DLC(tungsten-incorporated diamond-like carbon) and DLC were used. Results generally showed that adhesion and friction increased with the tip radius, and W-DLC and DLC surfaces were superior to Si-wafer. But the adhesion force of Si-wafer showed non linearity with the tip radius while W-DLC and DLC surfaces showed good correlation to the “JKR model”. It was found that high adhesion force between Si-wafer and a large radius of tip was caused by a capillary action due to the condensed water.

• 한국생산제조학회지
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• 제19권2호
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• pp.251-259
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• 2010

It is presented in this study a new efficient intelligent machining strategy, which can be used to remove the uncut volume at the boundary region of curved surfaces caused by cutter interference. The geometric form definitions and recognition of topological features of the surface triangulation mesh are used to generate cutter paths along successive and interconnected steepest pathways, that minimize the cusp height left after flat end milling. In order to machine the uncut volume gradually, the z-map cutter centers are adjusted to avoid cutter interference for the 6 kinds of avoidance types. And then, the generative subsequent paths are sequenced to determine the second step cutter paths for the next uncut volume. For the 2 kinds of test models with convex and concave surface region, the implemented software algorithm is evaluated by investigating the residual swelling of uncut volume for each machining step.

• Journal of the Optical Society of Korea
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• 제18권2호
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• pp.180-183
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• 2014

The surface of semiconductor solar cells, such as a-Si or CIGS (CuInGaSe) solar cells is not flat but textured in the microscopic domain. With textured surfaces, the optical reflectivity of a solar cell is different from that of flat surfaces in the wavelength region. In this paper, the effects of a textured surface on a CIGS solar cell are presented by RCWA (Rigorous Coupled Wave Analysis) method. The effect of incoherent light is also considered by RCWA with a Fourier analysis while conventional optical simulation uses the input light on the solar cell as coherent light. Using experimental results, the author showed that the RCWA method with a Fourier analysis is a proper method to simulate the optical properties of CIGS solar cells.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.773-776
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• 2005

An Experiment was carried out to study deburring in frilling hole on the Inclined exit surface. Two different deburring tools, exit surface angles, materials and cutting conditions were selected to check their performance using CNC machining center. In deburring operation, there are not only flat exit surfaces but also inclined exit surfaces which is described as inclination angle. Inclination of exit surface causes a quite different burr formation when comparing with flat surface. Deburring characteristics are analyzed according to the deburring tools and cutting conditions. Several strategies for a effective deburring on inclined exit surface were proposed.

• 한국CDE학회논문집
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• 제7권3호
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• pp.190-201
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• 2002

Surfaces of many engineering structures, specially, those of ships and airplanes are commonly fabricated as doubly curved shapes as well as singly curved surfaces to fulfill functional requirements. Given a three dimensional design surface, the first step in the fabrication process is unfolding or planar development of this surfaces into a planar shape so that the manufacturer can determine the initial shape of the flat plate. Also a good planar development enables the manufacturer to estimate the strain distribution required to form the design shape. In this paper, an algorithm for optimal approximated development of a general curved surface, including both singly and doubly curved surface is developed in the sense that the strain energy from its planar development to the design surface is minimized, subjected to some constraints. The development process is formulated into a constrained nonlinear programming problem, which is on basis of deformation theory and finite element. Constraints are subjected to characteristics of the fabrication method. Some examples on typical surfaces and the practical ship surfaces show the effectiveness of this algorithm.

• 한국지리정보학회지
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• 제3권1호
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• pp.44-56
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• 2000

Landsat TM 영상을 이용하여 곰소만 간석지의 미지형을 분류하고, 현지조사를 통하여 분류된 각 미지형의 퇴적물 입도 특성과 지형특성을 밝혔다. 내만 쪽의 mud flat는 갯골과 갯골 사이의 평탄지로 이루어져 있으며, 평균입경이 $4{\phi}$ 이하의 세립질이고 분급은 1 S.D. 이상이며, positive skewness를 보인다. 만구쪽에 분포하는 sand flat는 갯골이 없이 평탄한 지형을 이루며 ripple mark가 발달해 있다. 분급이 좋은 모래로 대부분 구성되어 있고 negative skewness를 보인다. mixed flat는 mud flat 와 sand flat와의 중간적 특징을 보인다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2005년도 제28회 학술발표회 초록집
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• pp.35-35
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• 2005

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.225-226
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• 2018