• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.294-295
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• 2011

본 논문에서는 스마트폰의 카메라와 플래시를 이용한 Shape from Shading 방법으로 3차원 형상 취득을 위한 카메라와 플래시의 보정 기법을 제시한다. 영상에서 관찰되는 화소 값은 카메라의 반응곡선에 의해 비선형적으로 표현되고 렌즈의 왜곡으로 인해 3차원 형상 복원에 오차를 발생 시킨다. 기하학적(geometric) 보정과 방사량(radiometric) 보정, 플래시 보정을 수행함으로써 3차원 형상 복원의 오차를 줄인다.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.36.3-37
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• 2016

ECS(Error Compensation Software)는 알루미늄 자유곡면 반사경의 형상정밀도를 향상시키기 위해 개발된 보정가공 소프트웨어이다. DTM(Diamond Turning Machine)을 이용한 가공공정에서 가공오차의 변화를 쉽게 확인하며 형상을 보정할 수 있도록 설계되었다. 보정가공 공정은 (1) 10차 다항식을 이용하여 표면을 설계한 후 DTM에 입력할 가공경로 계산, (2) DTM에 가공경로를 입력하여 가공, (3) 3차원 초정밀 형상측정 장비로 반사경의 가공오차 분석, (4) 가공오차를 보정하여 새로운 10차 다항식 설계, (5) 보정가공경로 계산 후 재가공으로 이루어진다. 그동안의 공정은 다항식의 설계, 가공경로 계산, 반사경의 가공오차 분석을 위해 다수의 프로그램들을 실행해야만 했다. 본 연구에서는 ECS가 알루미늄 자유곡면 반사경 제작을 위한 통합 보정가공 소프트웨어를 제공하여, 사용자가 작업을 효율적으로 수행하기를 기대한다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.116-116
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• 2003

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.7
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• pp.43-50
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• 2012

Database for the information of the shape accuracy is constructed with the finite element stamping analysis of the center pillar member. Analyses are carried out in order to investigate the effect of tool compensation on the product quality previously performed by an expert in the press shop. The compensation procedure is provided with three sequences for improving shape accuracy of the member by reducing the amount of springback. The analysis result shows that shape inaccuracy in the product is caused by sagging and twisting phenomena from displacement of the section part due to excessive amount of springback. From the database with springback analyses, design modification guidelines are proposed for improving the shape accuracy. The guideline is directly applied to a member with the similar shape and the sound product is obtained successfully reducing the amount of springback.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.10
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• pp.1923-1928
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• 2017

This paper is a study on error correction for three-dimensional shape reconstruction based on factorization method. The existing error correction method based on factorization has a limitation of correction because it is optimized globally. Thus in this paper, we propose our new method which can find and correct the only major error influence factor toward three-dimensional reconstructed shape instead of global approach. We define the error-influenced factor in two-dimensional re-projection deviation space and directly control the error components. In addition, it is possible to improve the error correcting performance by recursively applying the above process. This approach has an advantage under noise because it controls the major error components without depending on any geometric information. The performance evaluation of the proposed algorithm is verified by simulation with synthetic and real image sequence to demonstrate noise robustness.

• Proceedings of the Optical Society of Korea Conference
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• 2005.02a
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• pp.266-267
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• 2005

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.30-36
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• 2002

Wind tunnel model has some difference in shape compared to the real flight vehicle because of model support system for testing. The support system can make some differences in the measured forces and moments to the flight test data. There are several correction methods involved such as cavity pressure correction and model support interference. Internal balance and belly sting support were used for this wind tunnel test and three types of model support correction methods, variable sting thickness method, dummy sting method, and wire support method, were compared. Variable sting thickness method is well matched with wire support method, which is known for almost interference free.

• Korean Journal of Optics and Photonics
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• v.5 no.2
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• pp.191-197
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• 1994

We investigated the properties of various methods of 3 dimensional profilometry to choose the phase shifting technique for the reconstruction of the shape of a given specimen. The pattern was generated by a Twyman-Green interferometer and a PZT was used to shift the fringes on the target surface. The shape was calculated with Hariharan algorithm within the uncertainty of a scaling factor. The optical noise inherent in the laser source was observed to influence the final outcome to a great extent and the need for an exact calibration was noted. noted.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.1
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• pp.33-37
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• 2011

In the fields of display, optics, and energy, it is important to improve micropattern-machining technology for achieving small patterns, large surface areas, and low cost. Unlike flat molds, roll molds have the following advantages: they can be manufactured within a short time, larger surface areas can be obtained, and continuous molding can be achieved. In this study, we aim to investigate the causes for errors in the shapes for a micropattern-machining process, and we show that by compensating the dynamic balance of roll molds, the dimensional accuracy of machined parts can be improved. The experimental results show that dynamic-balance compensation for a roll mold reduced the mass unbalance and the vibrations of the roll mold, and as a result, the dimensional accuracy of machined micropatterns has been improved.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.9
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• pp.916-922
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• 2009

Because thermal design of satellite carrying out mission in space is performed by thermal analysis result using thermal mathematical model, accuracy of thermal mathematical model is important and it can be improved by model correlation. Correlation steps of satellite thermal math model are composed of modeling of satellite configuration placed in thermal vacuum chamber, verification of correspondence between thermal math model and real satellite configuration, and adjustment of modeling parameters from major part to minor part etc. In this study, correlation success criteria was established and correlation for satellite thermal math model was performed using result of thermal vacuum test of satellite structure-thermal model to meet the success criteria. The overall results satisfied the criteria and this correlated thermal model was applied for detailed thermal design of satellite.