• 대한기계학회논문집A
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• 제28권6호
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• pp.867-875
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• 2004

In order to inspect burr geometry and hole quality in micro-drilling processes, a cost-effective method using an image processing and shape from focus (SFF) methods on the machine tool is proposed. A CCD camera with a zoom lens and a novel illumination unit is used in this paper. Since the on-machine vision unit is incorporated with the CNC function of the machine tool, direct measurement and condition monitoring of micro-drilling processes are conducted between drilling processes on the machine tool. Stainless steel and hardened tool steel are used as specimens, as well as twist drills made of carbide are used in experiments. Validity of the developed system is confirmed through experiments.

• 대한기계학회논문집A
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• 제30권6호
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• pp.713-721
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• 2006

Micro-drill wear deteriorates accuracy and productivity of the micro components. In order to improve productivity and qualify of micro components, it is required to investigate micro-drill wear exactly. In this study, a machine vision system is proposed to measure the wear of micro-drills using a precision servo stage. Calibration experiments are conducted to compensate for the machine vision system. In this paper, worn volume, area and length are defined as wear amounts. Micro-drill wear is reconstructed as the 3D topography and the quantized wear amount by using the shape from focus (SFF) method and wear parameters. Experiments have been conducted with HSS twist micro-drills and SM45C carbon steel workpieces. Validity of the proposed machine vision system is confirmed through experiments.

• 한국정밀공학회지
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• 제14권3호
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• pp.28-34
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• 1997

The side burrs and shape distortion resulting from the micromachining of an array of V-shape microgrooves in fresnel lens mould were experimentally invesigated. The focus of this study is on the influence of depth of cut and prism angle on the burr growing rate. The main experiments were con- ducted on the single prism cutting for the convinient of measuring the burr shape and cutting force. From the observation of the burr shape and burr growing rate, it was found that there exits a critical depth of cut below which the burrs are more or less irregular and weak. But above that critical value, the burrs are re- latively clear and stiff.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.53.2-53
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• 2001

The Non-Contact Optical Sensor using the Hologram Laser for CD Pickup was developed to measure a shape of transparent objects and shown a good performance. Therefore the problems caused by the contact sensor are solved by using the Non-Contact Sensor. The Non-Contact Sensor has to move toward the objects and obtain the Focus Error Signal to measure a position of transparent objects. However, if the distance between the sensor and the object is shorter than the working distance of the objective lens, the sensor will be collided against the objects. In this paper we proposed a new algorithm to estimate the start position of the Focus Error Signal to solve the problems of collision between the sensor and the objects. In addition, we verified that the algorithm is free from the collision in the real time measurement.

• Current Optics and Photonics
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• 제8권2호
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• pp.170-182
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• 2024

The dimensional accuracy and consistency of a dual oil circuit centrifugal fuel nozzle are important for fuel distribution and combustion efficiency in an engine combustion chamber. A point cloud measurement method was proposed to solve the geometric accuracy detection problem for the fuel nozzle. An improved variance focus measure operator was used to extract the depth point cloud. Compared with other traditional sharpness evaluation functions, the improved operator can generate the best evaluation curve, and has the least noise and the shortest calculation time. The experimental results of point cloud slicing measurement show that the best window size is 24 × 24 pixels. In the height measurement experiment of the standard sample block, the relative error is 2.32%, and in the fuel nozzle cone angle measurement experiment, the relative error is 2.46%, which can meet the high precision requirements of a dual oil circuit centrifugal fuel nozzle.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2009년도 학술대회
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• pp.669-672
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• 2009

제안된 방법은 3차원 모델로부터 형상 기술자를 추출하고, 형상의 유사성을 비교하기 위해 특징 기술자를 이용한다. 대부분의 검색 방법들은 데이터베이스에서 개별적인 3차원 모델의 비교와 검색에 중점이 되어있지만, 본 유사성 검색 방법은 형상 유사성을 이용하여 3차원 물체의 부재 비교와 검색에 초점이 맞추었다. 물체의 부재 유사성 검색 방법은 3차원 모델들의 유사한 부분을 찾는 것과 유사한 부분을 포함하는 3차원 모델을 찾는 것으로 확장된다. 성능 평가를 위한 실험에서 유사한 3차원 석탑 모델의 부재를 효과적으로 검색하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.907-908
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• 2008

Estimation of surface roughness is an important quality measure for many applications including optics, polymers, semiconductor etc. In this paper, we propose to estimate surface roughness using image focus. We use polymers as test objects. The proposed method is an inexpensive and fast method based on Shape From Focus (SFF). We show that the results from SFF are encouraging for comparison of polymers using surface roughness.

• International Journal of Aeronautical and Space Sciences
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• 제12권3호
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• pp.225-240
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• 2011

Active and shape morphing aerospace structures are discussed with a focus on activities aimed at practical implementation. In active structures applications range from dynamic load alleviation in aircraft and spacecraft up to static and dynamic shape control. In contrast, shape morphing means strong shape variation according to different mission status and needs, aiming to enhance functionality and performance over wide flight and mission regimes. The interaction of required flexible materials with the morphing structure and the actuating mechanisms is specifically addressed together with approaches in design and simulation.

• KSTLE International Journal
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• 제4권1호
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• pp.31-36
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• 2003

Sliding and impact/sliding wear test in room temperature air and water were performed to evaluate the effect of spring shapes on the wear mechanism of a fuel rod. The main focus was to quantitatively compare the wear behavior of a fuel rod with different support springs (i.e. two concaves, a convex and a flat shape) using a ratio of wear volume to worn area (De)-The results indicated that the wear volumes at each spring condition were varied with the change of test environment and loading type. However, the relationship between the wear volume and worn area was determined by only spring shape even though the wear tests were carried out at different test conditions. From the above results, the optimized spring shape which has more wear-resistant could be determined using the analysis results of the relation between the variation of De and worn surface observations in each test condition.

• 대한기계학회논문집A
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• 제30권5호
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• pp.496-504
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• 2006

Wear of engine valves and seat inserts is a major factor affecting engine performance. In order to improve quality and life of valve assemblies, wear mechanism and 3-D surface topography should be analyzed according to operating conditions of the engine. After developing an engine simulator that generates valve speed up to 90Hz and temperature up to $900^{\circ}C$ as well as controls test load, wear experiments have been conducted for two different engine speeds as 10Hz and 25Hz. In order to observe the wear characteristics and monitor surface conditions of the valve assemblies, a cost-effective 3-D wear analysis system based on the shape from focus(SFF) and machine vision has been fabricated in this paper. 3-D surface topography of the valve assemblies has been analyzed to understand the wear behavior according to operating conditions of the engine. Consequently, wear volume of the valve assemblies is quantized by using the developed 3-D wear analysis system.