• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 춘계학술대회논문집
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• pp.143-145
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• 2005

We present the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ passive devices such as wave plate and polarizer, and calculate the phase at each point of the speckle pattern in shearographic system using Wollaston pin And, we analyzed the phase error caused by wave plates used in the proposed method by Jones matrix.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1998년도 가을 학술발표논문집 Vol.25 No.2 (2)
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• pp.327-329
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• 1998

Up-Propagation is an algorithm for inverting and learning neural network generative models. Sensory input is processed by inverting a model that generates patterns from hidden variables using top-down connections. The inversion process is iterative, utilizing a negative feedback loop that depends on an error signal propagated by bottom-up connections. The error signal is also used to learn the generative model from examples. the algorithm is benchmarked against principal component analysis in experiments on images of handwritten digits.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2005년도 학술대회 논문집
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• pp.185-188
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• 2005

We present the method to obtain four speckle patterns with relative phase shift of ${\pi}/2$ by passive devices such as wave plate and polarizer, and calculate the phase at each point of the speckle pattern in shearographic system using Wollaston prism. And, we analyzed the phase error caused using wave plates by Jones matrix.

• Journal of the Optical Society of Korea
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• 제9권4호
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• pp.145-150
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• 2005

The method to obtain four speckle patterns with relative phase shift of $\pi$/2 by passive devices such as two waveplates and a linear polarizer, and to calculate the phase at each point of the speckle pattern in shearography with a Wollaston prism is described. In this paper, we analyze its potential error sources caused by wave plates.

• 한국자동차공학회논문집
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• 제22권1호
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• pp.95-102
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• 2014

This paper presents zero crossing point(ZCP) estimation methods considering discretization error for a high speed brushless DC(BLDC) motor drive. The ZCP is estimated by detecting the change of back-EMF polarity for the BLDC sensorless drive, and the discretization error exist on the estimated ZCP. The discretization error of the ZCP is a cause of the delay of a commutation timing of current and increment of a current ripple factor. Besides a delay of a ZCP estimation brings on the limitation of a speed range for the BLDC sensorless drive. The compensation method based on the error analysis with probability theory for reducing the effects of the discretization error of the ZCP is proposed. Also a ZCP estimation method according to the Back-EMF patterns is proposed to widen the speed range for the BLDC sensorless drive. The proposed methods are verified by the experiment.

• 한국음향학회지
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• 제22권6호
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• pp.496-504
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• 2003

본 논문에서는 유전자 알고리즘을 이용하여 빔 패턴 오차의 허용범위를 만족하는 개별소자의 허용오차를 분석하였다. 기존의 수치적 통계방법은 배열소자의 개수증가에 따라 계산량이 증가하는 문제점이 있고 이를 보완하기 위해 제안된 Monte-Carlo 방법은 낮은 정밀도와 빔 패턴 합성으로의 확장이 어렵다는 한계점을 가지고 있어 본 논문에서는 이러한 단점을 극복하기 위해 유전자 알고리즘을 이용한 소나 배열 소자의 허용오차 분석법을 제안하였다. 제안된 알고리즘을 이용하여 1차원과 2차원 배열에서 주어진 빔 패턴 오차 허용범위를 만족하는 각 소자별 허용오차 범위를 분석하였고 모의실험을 통하여 소나 배열 소자의 허용오차 범위가 타당함을 검증하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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• pp.611-614
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• 2002

In this paper, a novel error concealment, algorithm is proposed for the MPEG-4 video decoding. Apart from existing algorithms which fail to exhibit stable performance over various video sequences and error patterns, the proposed algorithm adopts a new hybrid scheme, which can achieve a consistent performance with reduced computational complexity. This algorithm is implemented on the basis of the MPEG-4 decoder, and the experimental results demonstrate that the new approach provides acceptable performance both subjectively and objectively at various bit error rates and video sequences.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.121-127
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• 2008

Micro end-milling has been becoming an important machining process to manufacture a number of small products such as micro-devices, bio-chips, micro-patterns and so on. Despite the importance of micro end-milling, many related researches have given grand efforts to micro end-milling phenomenon, for example, micro end-milling mechanism, cutting force modeling and machinability. This paper strongly concerned actual problem, micro tool deflection, which causes excessive machining errors on the workpiece. To solve this problem, machining error prediction method was proposed through a series of test micro cutting and analysis of their SEM images. An iterative algorithm was applied in order to obtain corrected tool path which allows reducing machining errors in spite of tool deflection. Experiments are carried out to validate the proposed approaches. In result, remarkable error reduction could be obtained.

• 대한화학회지
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• 제46권4호
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• pp.353-363
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• 2002

이 연구의 목적은 일반고와 과학고 학생들의 정신용량과 풀이 방법에 따른 산화 환원 반응식 완결 과정의 특성을 분석하여 산화 환원 단원의 교수학습 지도에 시사점을 얻고자 하는데 있다. 일반고 학생 79명과 과학고 학생 57명을 대상으로 하여 정신요량 검사, 산화 환원 반응식 완결 검사를 실시하였으며, 문항 유형별로 학생들의 문제 풀이 실패 유형과 성공 유형을 추출하여 분석틀을 개발하고 개발한 분석틀에 의하여 정신용량과 풀이 방법에 따라 실패 사례와 성공 사례를 분석하여 나타나는 특징을 알아보았다. 일반고 학생들과 과학고 학생들 모두 산화 환원 개념 이해 정도가 낮을수록 미정계수법을 많이 선택하였으며 미정계수법을 선택한 학생들은 정신용량이 클수록 문제 풀이의 성공률이 높았다. 또한, 산화 환원 개념 이해 정도가 높은 학생들은 산화수법이나 이온 자법을 더 많이 선택하였고 정신용량에 관계없이 문제 풀이의 성공률이 높게 나타났다. 학생들의 풀이 과정을 분석한 결과 성공 유형은 산화 환원의 개념 이해 정도가 높고 풀이 방법에 관계없이 풀이 단계 수를 줄이 학생들이었다. 실패 유형은 물이 방법에 따라 다르게 나타났다. 미정계수법을 선택한 학생들의 실패 유형은 계산 과정 중 틀린 경우, 미정방정식을 잘못 세운 경우 문제 풀이 과정중 고려해야 할 변인을 모두 고려하지 못한 경우 풀이 과정이 복잡하여 중단한 경우였다. 산화수법을 선택한 학생들의 실패 유형은 산화수를 잘못 결정한 경우 질량균형 또는 전하균형을 고려하지 않은 경우였다.

• 천문학회보
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• 제40권2호
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• pp.40.1-40.1
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• 2015

Off-axis reflective optical systems have attractive advantages relative to their on-axis or refractive counterparts, for example, zero chromatic aberration, no obstruction, and a wide field of view. For the efficient operation of off-axis reflective system, the surface accuracy of freeform mirrors should be higher than the order of wavelengths at which the reflective optical systems operate. Especially for applications in shorter wavelength regions, such as visible and ultraviolet, higher surface accuracy of freeform mirrors is required to minimize the light scattering. In this work, we propose the error compensation algorithm (ECA) for the correction of wavefront errors on freeform mirrors. The ECA converts a form error pattern into polynomial expression by fitting a least square method. The error pattern is measured by using an ultra-high accurate 3-D profilometer (UA3P, Panasonic Corp.). The measured data are fitted by two fitting models: Sag (Delta Z) data model and form (Z) data model. To evaluate fitting accuracy of these models, we compared the fitted error patterns with the measured error pattern.