• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.169-179
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• 1998

Plane mirror type laser interferometers are popularly being used in many modern ultraprecision machines, as they can perform simultaneous measurements of multiple axis positions with nanometer resolution capabilities. One important issue in this application of laser interferometers is to provide a good level of alignment between the reflecting mirrors and the laser beams so that measurement errors due to undesirable coupling effects can be avoided in multiple axis measurements In this investigation, a thorough metrological analysis is given to develop an suitable mathematical model for a precision x-y stage in which the orthogonality misalignment between the reflecting mirrors significantly affects overall x-y mea-surement results. Then a noble calibration method is suggested in which two-dimensional displacement sensors of moire gratings of concentric circles are used to realize the reversal principle of orthogonality evaluation in situ. Finally, actual experimental results are discussed to verify that the suggested method can effectively calibrate the orthogonality error with an uncertainty of 0.2667 arcsec.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.6
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• pp.210-217
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• 2000

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and it's high sensitivity. Especially when projecting a grid pattern over the object, the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, the projection moire are compared with the PMP mathematically, and it is shown that PMP can generate moire image with simple mathematical computations. Experimental works are also carried out showing the same results. It is shown that using a single gird pattern, moire image can be obtained directly without any mathematical operation when some conditions are satisfied.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.11a
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• pp.237-238
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• 2013

The quality of document image captured from electronic display might be worse when it is compared with document image captured from paper. The problem appears because of Moir? noise. This problem can lead to achieve inaccurate intermediate result for further image processing. This paper proposes a method to remove Moir? noise of document images captured from electronic display. The proposed algorithm is separated in two parts. In the first step, it corrects the text area region (foreground) with small area of smoothing. Then, it corrects the background area with large area of smoothing.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.19-22
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• 2000

Noncontact measuring methodology of 3-dimensional profile using CCD camera are very attractive because of it's high measuring speed and its's high sensitivity. Especially, when projecting a grid pattern over the object the captured image have 3 dimensional information of the object. Projection moire extract 3-D information with another grid pattern in front of CCD camera. However phase measuring profilometry(PMP) obtain similar results without additional grid pattern. In this paper, new method for grid pattern generation system by polygonal mirror and Laser Diode. This system is applied the projection moire and the PMP.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.3
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• pp.103-110
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• 2000

Shaft encoder which encodes the rotational angle of a shaft becomes more important recently due to factory automation and office automation. Although an absolute type encoder is more dsirable due to its convenience an incremental encoder is commonly used because of its cost and technical difficulties Fabricating a high resolution absolute encoder is very diff-cult because the physical size is limited by currently available technology. In order to overcome this difficulty Moire fringe can be used incorporated with gray code. In order to measure the position of fringes which move as the code disk rotates a neural network was developed in this paper. Formerly fringe position is usually measured by a sophisticated software which needs a little long calculation time. However using nerual network method can eliminate such calculation time even though it needs learning job The pro-posed method is verified through several experiments.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2003.11a
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• pp.28-32
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• 2003

Thermo-mechanical behavior of a ceramic ball grid array(CBGA) package assembly and wire bond ball grid array(WB-PBGA) package assemblies are characterized by high sensitive moire interferometry. Moire fringe patterns are recorded and analyzed at various temperatures in a temperature cycle. Thermal-history dependent analyses of global and local deformations are presented, and bending deformation(warpage) of the package and shear strain in the rightmost solder ball are discussed. A significant non-linear global behavior is documented due to stress relaxation at high temperature. The locations of the critical solder ball in WB-PBGA package assemblies are documented.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.320-325
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• 1999

An absolute type shaft encoder which utilized moire fringe will be presented in this paper. Linear moire fringe is commonly used to measure the displacement of the linear motion. However, an absolute encoder which measure the rotation angle of a shaft is operated usually with a code disk which the gray code pattern is printed on. Such encoder has inherently resolution limit because of the patterning mechanism and sensing mechanism. In order to measure the position of fringes which move as the code disk rotates, neural network was developed in this paper. Formerly fringe position is usually measured by a sophisticated software, which needs a little long calculation time. However, using neural network method can eliminate such calculation time, even though it needs learning job. The proposed method is verified through several experiments.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.11a
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• pp.239-244
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• 2000

영상공간에서의 역 해프토닝 성능을 향상시키기 위해서는 정확한 해프톤 셀 정보를 기반으로 최적의 평활화 마스크가 생성되어야 한다. 이에 본 논문에서는, 퓨리에 공간에서 피크형태와 영상공간에서의 해프토닝 특성을 이용해서 정확한 해프톤 셀 정보를 추출하는 새로운 방법을 제안한다. 제안한 방법은 차원분해(dimension decomposition)와 제한된 구간의 자동 탐색에 의해 정확한 해프톤 셀 정보를 효율적으로 추출하므로 역 해프토닝의 성능을 향상 시키며, 전체 영상에서 오차의 누적없이 셀 중심(seed pixel)을 정확하게 찾는 것을 실험을 통해 확인하였다. 정확한 해프톤 셀 정보는 셀 단위의 연산이나 해프톤 영상의 채널 분리 및 모아레 패턴의 존재 여부 판정 시 활용할 수 있다.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1407-1412
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• 2003

In MEMS devices, packaging induced stress or stress induced structure deformation become increasing concerns since it directly affects the performance of the device. In this paper, deformation behavior of MEMS gyroscope package subjected to temparature change is investigated using high-sensitivity $Moir{\acute{e}}$ interferometry. Using the real-time $Moir{\acute{e}}$ setup, fringe patterns are recorded and analyzed at several temperatures. Temperature dependent analyses of warpages and extensions/contractions of the package are presented. Linear elastic behavior is documented in the temperature region of room temperature to $125^{\circ}C$. Analysis of the package reveals that global bending occurs due to the mismatch of thermal expansion coefficient between the chip, the molding compond and the PCB.

• Journal of the Korean Society of Clothing and Textiles
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• v.19 no.2
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• pp.366-379
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• 1995

This study was performed to provide fundamental data on middle-aged women's upper torso by classifying the upper torso somatotype and analyzing the characteristics of their somatotype. Factor analysis of principal component model was used to 38 directly measured items, and cluster analysis was applied for classification of upper torso forms. Seven factors were extracted from the factor analysis. The first factor represented the items of circumference, breadth, and depth which were related with body size. On the basis of the cluster analysis using factor scores trom factor analysis as being independent variables, the subjects were classified into three groups. Three dress forms were constructed according to the characteristics for each somatotype of subjects, the three-dimensional characteristics of somatotype were analyzied by the moire pattern and horizontal section map of proposed dress forms. Wearing test by moire topography was used to evaluate wearing outline, the ease of clothes and garment space. Moire pattern and horizontal section map were useful to evaluate wearing conditions, and garment space was changed by the characteristics of the body shape.