• Journal of the Korean Society for Precision Engineering
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• v.11 no.2
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• pp.120-133
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• 1994

홀로그래픽 간섭계측기로터 나오는 영상 데이터를 해석하는 전문가시스템에 대하여 기술하였다. 그동안 간섭 띠무늬(fringe)를 해석하는 방법들이 어느 정도의 자동화를 이룩하며 개발되어왔다. 그러나, 복잡한 간섭 띠무늬 패턴(fringe pattern)및 심한 잡음이 생기게 되는 고속도 항공공학 분야 또는 실험기계공학 분야에서는 신뢰할 만한 자동화를 이룩하기가 매우 힘들었다. 현재 사용가능한 방법중에는 간섭띠무늬 추적, 위상전이, 푸리에 변환, 회귀분석 등이 있는데, 이들은 소음제거나 데이터 수정을 하는데 있어서 극히 국부적인 정보에만 의존하였다. 결과적으로, 특별히 심한 소음이 있는 경우, 부정확한 위상중첩이나 간섭띠무늬 순차배열문제에 부딪히게 되고 따라서 작업자의 수작업이 심각하게 필요하게 된다. 본 논문에서는 간섭띠무늬 추적방법의 자동화 를 위한 새롭고 포괄적인, 규칙기반 전문가시스템에 대하여 기술하였다. 새로 개발된 전문가 시스템은 간섭띠무늬 패턴에 대한 전체적인 또는 지연적인 정보를 추출해 내고 또 전문가가 가지고 있는 지식을 이용한다. 이 전문가 시스템은 저수준 및 고수준 처리를 동시에 할 수 있도록 상호연결기구를 채택하여 간섭띠무늬를 해석하는 적절한 해결책을 마련하였다. 또한 위상전이나 푸리에 변환 방법에서 문제가 되는 자동위상 중첩에 대해 개발된 전문가 시스템의 응용의 가능성에 대해서도 기술하였다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.5
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• pp.36-42
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• 1993

최근 반도체기술의 발달과 마이크로프로세서 제어기술의 발달로 유도전동기의 정밀제어가 가능해졌다. 유도전동기로서 고 응답성을 확보하기 위하여 주로 벡터제어방식을 도입하였다. 그러나 시스템이 모터 파라미터의 변화에 따라서 성능이 저하되거나 또는 불안정해질 수 도 있다. 특히 모터 파라미터변화의 하나로서 온도상승에 따른 모터 2차저항값의 변화는 시스템 성능에 심한 영향을 끼친다. 본 논문에서는 이에 대한 대책으로 파라미터를 동정하는 벡터제어방식을 연구하였다. 유도전동기의 2차저항을 동정하기 위해서 2차쇄교자속상의 1차전류에 교류분을 중첩시키는 것이 필요하였으며 동정시점의 결정은 2차전류가 정격의 1.5배에서 1분 경과한 때를 동정의 시점으로 하였다. 동정알고리즘은 등가 피이드백계를 도출하고 그것을 이용해 안정성이 확보되는 것을 확인할 수 있었다.본 논문에서는 온도변화가 클 경우에만 모터 파라미터를 동정하여 제어 파라미터를 수정하므로써 정밀도의 향상뿐만 아니라 속응성의 향상도 기대할 수 있다.

• Economic and Environmental Geology
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• v.49 no.5
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• pp.381-388
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• 2016

The purpose of this study is to integrate and visualize using mapping techniques based on precise seabed geomorphology, seafloor backscattering images and high-resolution underwater images of the nearshore area around the Dokdo, in the East Sea. We have been obtained the precise topography map using multibeam echosounder system around the nearshore area(~50 m) of the southern part of the Seodo. Side scan sonar survey for analysis seafloor backscattering images was carried out in the same area of topography data. High-resolution underwater images(zone(a), zone(b), zone(c)) were taken in significant habitat scope of the nearshore area of the southern part of the Seodo. Using the results of bathymetry, seafloor backscattering images, high-resolution underwater images, we performed an integrated visualization about the nearshore area of the Dokdo. The integrated visualizing techniques are possible to make the seabed characteristic mapping results of the nearshore area of the Dokdo. The integrated visualization results present more complex and reliable information than separate geological products for seabed environmental mapping study and it is useful to understand the relation between seafloor characteristics and topographic environments of the study area. The integrated visualizing techniques and mapping analysis need to study sustainably and periodically, for effective monitoring of the nearshore ecosystem of the Dokdo.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.639-645
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• 2018

The objective of this research was to compare the precision of scanning the digital abutment impression and gypsum model according to 3-dimensional superimposing different skills. There were made with the abutment impression and gypsum model of a maxillary 1st premolar, blue light scanner scanned to obtain the stereolithography (STL) file. After the same process was performed 10 more times without moving them on the scanner table about the abutment impression and gypsum model, respectively (n=11, per types). By superimposing the date of scanning the abutment impression and gypsum model used with no control and best-fit-alignment skills, 10 color-difference maps and root mean square (RMS) data were obtained. The independent t-test was performed to compare RMS data between the each other groups (${\alpha}=0.05$). In the scanning abutment impressions, $RMS{\pm}SD$ of no control, best-fit-alignment showed $6.86{\pm}0.94$, $5.04{\pm}0.24$. in the scanning gypsum model, $4.98{\pm}1.16$, $3.39{\pm}0.07$, all groups showed a significant difference (P<0.001). Trough the this study's result, not only best-fit-alignment but no control is used with digital dental computer-aided design/computer-aided manufacturing (CAD/CAM) research and clinical part.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.284-285
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• 2003

극저온복사계로부터 출발하여 광도의 기본 단위인 칸델라(Candela) 눈금은 물론 복사조도(irradiance), 조명도(illuminance)와 같은 유도 단위를 실현하기 위해서는 검출기의 시야를 한정하는 구멍의 면적을 측정하는 기술이 매우 중요하다. 구멍의 면적을 측정하는 한가지 방법은 탐촉자를 물리적으로 접촉시켜서 구멍의 가장자리를 결정하고, 구멍의 기하학적 모양을 가정하여 면적을 계산하는 것이다. (중략)

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.301-304
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• 2002

Powertrain simulation is important fur the analysis of a vehicle performance. Automotive powertrain has been considered as the unified system and should be remodeled, whenever a powertrain system is changed. In this study, a new method is proposed for the synthetic modeling for the automotive powertrain. Components are separated from the powertrain system and constructed the matrix through dynamic relationships. The dynamic equation of the total powertrain system can be driven from the combination of each component. In order to combine each component, the superposition method is modified for the powertrain composition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.402-406
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• 1995

The shadow moire is one the optical techniques which able to give contour lines of an object with respect to a master grating plane. The moire patterns are issued from the superposition of a grating and its shadow projected on the surface of an object. But in the conventional shadow moire method the reference grating and deformed grating are mutually dependent, it is impossible to obtain uniform phase shifts on the whole field by moving the reference grating. Here we propose ane trial to apply phase shifting to conventional shadow moire. When, in the conventional arrangement, Phase-shifting that is sctually constant regardless of fringe orders is achieved by moving the grating and the light source. Finally we obtained a better result by using this procedure and applied the phase shifting shadow moire to three dimensional measurement.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.96-100
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• 1997

The shadow moire is one of the optical techniques which is able to give contour lines of an object with respect to a master grating plane. The moire patterns are issued from the superposition of a master grating and its shadow projected on the surface of an object. In case of the classical shadow moire method, the sensitivity was a few tenths millimeters. generally, it is difficult to use a phase shift method in shadow moire because it is impossible to obtain uniform phase shifts on the whole field. But in this study we use the fact that if the depth of object is much less than the distance between the observer and the master grating, and the object is displaced perpendicularly to the grating plane, phase shifts are almost uniform. Finally we obtained a better resolution by using a phase shift procedure and applied the phase shifting shadow moire to three dimensional shape measurement.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.217-225
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• 2000

Scanning Acoustic Microscope (SAM) is used as an important nondestructive test tool in semiconductor reliability evaluation and failure analysis. However, inspections of chip attach adhesive interface fer thin chip has proven difficulty as the reflected signals from the chip top and bottom are superimposed. In this paper, in order to overcome this difficulty, a new signal processing method based on the deconvolution technique combined with the wavelet transform is proposed. The wavelet transform complements a disability of deconvolution technique of which performance largely decreases when the waveform of target signal is not identical to that of reference signal. Performances of the proposed method are demonstrated by through computer simulations using model signal and experiments for the fabricated semiconductor samples, and satisfactory results are obtained.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.6
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• pp.114-122
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• 1999

By using the FEM, a method for the stress analysis of the presented dies has been proposed. In this method, FEM and Lame equation are used for the analysis of the die insert and the stress ring, respectively. The proposed method includes the calculation of the contact pressure between the die insert and the stress ring. To show the validity, the proposed method has been applied to the simple test problem. The results of the stress analysis have been compared with the results of ANSYS, a commercial FE-code. Cold extrusion has been simulated by using the rigid-plastic FEM and the results of the deformation analysis have been used as the input of the die structure analysis. The stress states of the prestressed extrusion die have been obtained. The stress analysis of the die insert with stress rings has also been performed during extrusion.