• Journal of Welding and Joining
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• 제20권2호
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• pp.71-76
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• 2002

Currently knowledge of strain in welds has mainly been obtained from strain gage method; that is directly attaching the gage to the most of the material. The very flew non-contact methods are still in the early stage. One of the non-contact methods is by the use of the laser that has high-level of the accuracy for the measurement, and this laser also has excellent characteristics on which many studies for its applications are focused throughout the many fields. The paper is on the measurement of the strain caused by the characteristics and the temperature changes of the GTA welded zone employed with 3D ESPI system that is functionally modified through the laser ESPI system. This system may be applied the steel plate such as for the electronics, chemistry, flood instrument and electronic appliances.

• Design & Manufacturing
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• 제15권4호
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• pp.65-71
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• 2021

In the early days of laser invention, it was simply used as a measuring tool, but as lasers became more common, they became an indispensable processing tool in the industry. Short-wavelength lasers are used to make patterns on wafers used in semiconductors depending on the wavelength, such as CO2 laser, YAG laser, green laser, and UV laser. At first, the hole of the PCB board mainly used for electronic parts was not thin and the hole size was large, so a mechanical drill was used. However, in order to realize product miniaturization and high integration, small hole processing lasers have become essential, and pattern exposure for small hole sizes has become essential. This paper intends to analyze the characteristics through patterns by exposing the PCB substrate through DMD and polygon scanner, which are different optical systems. Since the optical systems are different, the size of the patterns was made the same, and exposure was performed under the optimal conditions for each system. Pattern characteristics were analyzed through a 3D profiler. As a result of the analysis, there was no significant difference in line width between the two systems. However, it was confirmed that dmd had better pattern precision and polygon scanner had better productivity.

• 한국재료학회지
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• 제14권3호
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• pp.186-190
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• 2004

An electron beam microcolumn composed of an electron emitter, micro lenses, scan deflector, and focus lenses have been fabricated and tested in the STEM mode. In this paper, we report a technique of precisely aligning the electron lenses by the laser diffraction patterns instead of the conventional alignment method based on aligner and STM. STEM images of a standard Cu-grid were observed using a fabricated microcolumn under both the retarding and accelerating modes.

• 제어로봇시스템학회논문지
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• 제14권10호
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• pp.1005-1013
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• 2008

This paper describes a new sensor system for 3D range measurement using the structured infrared light. Environment and obstacle sensing is the key issue for mobile robot localization and navigation. Laser scanners and infrared scanners cover $180^{\circ}$ and are accurate but too expensive. Those sensors use rotating light beams so that the range measurements are constrained on a plane. 3D measurements are much more useful in many ways for obstacle detection, map building and localization. Stereo vision is very common way of getting the depth information of 3D environment. However, it requires that the correspondence should be clearly identified and it also heavily depends on the light condition of the environment. Instead of using stereo camera, monocular camera and the projected infrared light are used in order to reduce the effects of the ambient light while getting 3D depth map. Modeling of the projected light pattern enabled precise estimation of the range. Identification of the cells from the pattern is the key issue in the proposed method. Several methods of correctly identifying the cells are discussed and verified with experiments.

• 정보저장시스템학회:학술대회논문집
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• 정보저장시스템학회 2005년도 추계학술대회 논문집
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• pp.119-123
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• 2005

We report the random pattern characteristics of the super resolution near field structure(Super-RENS) write once read-many(WORM) disc at a blue laser optical system(laser wavelength 405nm, numerical aperture 0.85) and the Super-RENS read only memory(ROM) disc at a blue laser optical system(laser wavelength 659nm, numerical aperture 0.65). We used the WORM disc of which carrier-to-noise ratio (CNR) of 75nm is 47dB and ROM disc of which carrier-to-noise ratio (CNR) of 173nm is 45dB. We controlled the equalization (EQ) characteristics and used advanced partial-response maximum likelihood (PRML) technique. We obtained bit error rate (bER) of 10-3 level at 50GB WORM disc and bite error rate of 10-4 level at 50GB level ROM disc. This result shows high feasibility of Super-RENS technology for practical use.

• 정보저장시스템학회논문집
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• 제2권1호
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• pp.38-42
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• 2006

We report the random pattern characteristics of the super resolution near field structure(Super-RENS) write once read-many(WORM) disc at a blue laser optical system(laser wavelength 405nm, numerical aperture 0.85) and the Super-RENS read only memory(ROM) disc at a blue laser optical system(laser wavelength 659nm, numerical aperture 0.65). We used the WORM disc of which carrier-to-noise ratio(CNR) of 75nm is 47dB and ROM disc of which carrier-to-noise ratio(CNR) of 173nm is 45dB. We controlled the equalization(EQ) characteristics and used advanced partial-response maximum likelihood(PRML) technique. We obtained bit error rate(bER) of 10-3 level at 50GB WORM disc and bite error rate of 10-4 level at 50GB level ROM disc. This result shows high feasibility of Super-RENS technology for practical use.

• 소성∙가공
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• 제20권1호
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• pp.60-63
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• 2011

BLU(back light unit) is one of kernel parts of LCD(liquid crystal display) unit. New 3-D micro-lens pattern for LGP(light guide plate), one of the most important parts of LCD-BLU, had been researched. Instead of dot pattern made by chemical etching or laser ablation, SCS(slanted curved surface) micro-lens pattern was designed with optical CAE simulation. This study introduce the method of design using optical CAE simulation for SCS micro-lens, the new fabrication method of micro-mold with SCS micro-lens pattern.

• 대한토목학회논문집
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• 제29권4D호
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• pp.555-561
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• 2009

굴착된 터널 형상 재현에서 단면의 종단 데이터는 터널의 유지를 위해서는 아주 중요하다. 터널이 완성되기전에 설계된 모델을 고려한 완성된 터널의 변형이 고려되어져야 한다. 그리고 변형은 터널 단면 전체를 따라 연속적으로 나타날 수 있다. 본 연구에서는 먼저 수학적 분석으로 접근하였고, 그것을 관측된 터널단면 데이터에 실험 하였다. 그 다음 선추적 방법, 유전자 알고리즘, 패턴 추적 방법 등으로 3D 터널 형상 재현을 비교하였다. 수학적 방법론은 철도 터널과 같은 간단한 원통형은 쉽게 해결이 되었으나, 도로터널과 같은 더욱 복잡한 모델(복심 곡선형과 비원통형)은 구속된 상태하에서 소프트 컴퓨팅 툴을 가지고 해결할 수 있었다. 유전자 알고리즘과 직접탐색법은 많은 계산 시간이 걸렸으나 복잡한 상태하에서 더욱 유연함을 보였으며, 선추적 방법은 초기값들이 제한된 범위 하에서 가장 빠르게 계산되어졌다.

• 한국통신학회논문지
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• 제37C권10호
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• pp.933-939
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• 2012

일반적으로 선박공정에서 작업자는 완성된 블록을 레이저 계측장비를 이용하여 제작된 선박블록의 3차원 좌표를 측정한다. 그런데 제작된 선박블록의 좌표측정은 수작업으로 이루어졌으므로 이에 의한 측정된 좌표는 설계단계에서 작성된 도면의 설계좌표와 편차가 발생한다. 이로 인해 작업자는 육안으로 직접 선박블록의 측정좌표와 설계좌표의 일치정도를 확인해야 하며, 이는 선박불록의 정도관리에 대한 인적 및 시간적 비용을 크게 증가시킨다. 본 논문에서는 선박공정의 선박블록의 정도관리에 있어서 이러한 단점을 해결할 수 있는 자동화된 3차원 좌표의 패턴매칭 알고리즘을 제안하고, 제안한 3차원 좌표의 패턴매칭 알고리즘의 성능은 자체적으로 개발한 3차원 좌표 시뮬레이션 프로그램에 의해 분석하였다. 단일 및 다수 선박블록의 측정좌표 데이터에 대한 좌표매칭율은 거리오차 허용범위가 20~25cm에서 약 90.2%가 됨을 확인하였다.

• 전자공학회논문지CI
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• 제42권1호
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• pp.51-58
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• 2005

레이저 스트라이프 신호를 물체에 투사하고 그 반사파형을 비전 카메라를 통하여 입력하면 물체의 입체적 정보를 갖는 파형이 나타나게 된다. 이를 활용하여 물체의 3차인 입체정보를 저장하고 활용하고 있는 상황이다. 본 연구는 사람에 대해 적은 수의 스트라이프 신호를 투사하고 반사된 입체적 스트라이프 파형을 분석하였으며 사람에 대한 특징적 패턴 파형을 추출하고 푸리에 서술자를 이용하여 이러한 패턴을 분류 저장하였다. Baum-Welch 알고리즘을 통하여 저장된 특징 파형을 학습시키고 HMM을 이용하여 사람의 형상에 대한 스트라이프 신호를 컴퓨터에 입력하고 사람의 형상을 인식할 수 있는 지를 실험하였으며 푸리에 서술자를 통한 인식방법과 비교하였다. 실험을 통해서 특정 파형으로 학습 후 인체의 형상을 인식할 수 있음을 확인하였으며, HMM을 통한 인식방법이 우수함을 알 수 있었다.