• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.145-153
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• 1994

In the fabrication of welded built-up beams, longitudinal deformation occurs due to welding, and this obstructs improvement of productivity and quality. In this study, to estimate the deformation due to welding, a simplified thermal elasto-plastic analysis method is proposed and verified by experiments. From the results of the simplified analysis, it is clarified that deformation coefficients defined in this study are the function of fabrication parameters. Based on this simplified analysis, a method to simulate the fabrication procedures for the built-up beams can be developed.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.154-164
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• 1994

In this study, to find an economical production method which yields welded built-up beams with high quality, simulation techniques and optimization method are used. At first, fabrication variables such as welding current, voltage and speed and heated depth and breadth are selected and fabrication cost of a built-up beam is expressed by these parameters, which is optimized under the constraints. As advanced studies, total production cost including the fabrication cost and the material cost of the beam is expressed by the fabrication and design variables, and optimized with the design constraints by the class rules. In addition, assuming that heating for straightening is impossible. the optimization method of multi-objective functions based on the weighting method is applied to obtain the compromised optimal solutions of the total production cost and the welding deformation.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.1
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• pp.206-213
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• 1996

Longitudinal deformation due to welding of built-up beams must be straightened for attachment with plates. Straightening of deformation is carried out by much experienced workers and requires much time and labor. In this study, a procedure to calculate the required reverse curvatures to straighten the welding deformation is presented and a method to simulate the fabrication procedures for the built-up beams is developed for the purpose of improvement of productivity.

• Journal of the Korean Wood Science and Technology
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• v.35 no.6
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• pp.118-125
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• 2007

To obtain design data for built-up beams used as headers in light-frame timber construction, three members of $2{\times}6$ ($38{\times}140 mm$), $2{\times}8$ ($38{\times}184 mm$), $2{\times}10$ ($38{\times}235 mm$) and $2{\times}12$ ($38{\times}286 mm$) were built up as specimens of bending tests. The bending strengths of built-up headers were obtained through bending tests of these specimens, and it was considered that span tables can be calculated for various loading conditions based on the bending strengths of built-up headers. The bending strengths of built-up headers were determined as the bending stresses at 10 mm deflection of specimens from the results of bending tests of built-up beam specimens. Span tables for built-up headers were considered to be obtained by assuming five loading conditions for headers used in exterior walls and two loading conditions for headers used in interior walls. Among these 7 loading conditions, 5 loading conditions applied to headers in exterior walls included dead loads, live loads and snow loads and 2 loading conditions applied to headers in interior walls included dead loads and live loads.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.24-30
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• 2021

In this study, an augmented reality (AR) app that detects the screw-assembly state of a car valve-body and assists the assembly work is developed and the effectiveness of the app is shown through testing. The app creates the contents indicating the screw-assembly position and order, and the screw-assembly state. Then, the contents are registrated onto the valve-body image on a smart-phone screen to be shown to the worker during assembly. To this end, the features are extracted from the 2D image of the valve-body and the location of the valve-body is tracked. By extracting the areas where the screws are to be assembled, and periodically determining the luminance of these areas, it is checked whether the screws are assembled in order at the predetermined position of the valve-body. When an error is detected during assembly, a warning sound is notified to the worker, and the worker can check the assembly state on the smart-phone screen and handle the error, immediately. Study results found that it takes about 65 ms to detect the assembly state of the five screws, and the assembly state is detected without error for 1 hour.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.154.2-154.2
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• 2012

액체로켓엔진 조립을 위한 엔진 조립장이 국내에 구축되어야 하며 이에 대하여 국내의 사례가 없으므로 해외 엔진 조립장의 사례를 조사하였다. SNECMA, EADS, Rocketdyne 등의 조립장의 구조, 레이아웃, 청정설비, 크레인 등을 조사하였다. SNECMA 엔진조립장은 Vulcain 엔진의 대형엔진 조립라인 및 HM7, Vinci 엔진 등의 소형엔진 조립라인으로 구성되어 있다. 청정도는 코어 및 Subassembly 조립실은 100 K class 이며, 기타 나머지 조립공간은 300K class로 구축되어 있다. EADS의 엔진 조립장은 중앙에 연소기 부품을 가공하는 가공장비들이 배치된 하이베이 구역이 있으며, 이 하이베이 구역의 측면에 사무실, 측정실, 회의실 등의 로우베이 기능실들이 배치되어 있다. Rocketdyne 엔진 조립시설은 청정도 300K class이하의 엄격한 청정도 관리가 없는 것으로 보이며 치구형태의 개별 플랫폼을 사용하여 공간 활용을 효율적으로 할 수 있도록 하고 있다.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.257-260
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• 2000

본 연구에서는 유한용량을 갖는 조립/분해 생산시스템의 산출율분석을 위한 근사적 방법을 제시한다. 유한용량을 갖는 조립/분해 생산시스템은 상태공간이 매우 크기 때문에 효율적으로 분석하기가 어렵다. 따라서 근사적 방법에서는 조립/분해 생산시스템을 비교적 작은 규모의 상태공간을 갖도록 단순 조런/분해 시스템과 단일 직렬시스템을 갖는 각각의 부분시스템으로 분해한다. 각 부분시스템은 2차 모멘트가 고려된 PH/Ph/1/C 시스템으로 기술되고 수리적 방법에 의해 분석되어진다. 실험결과는 시뮬레이션과 비교되고, 제시된 근사적 방법이 효과적이라는 것을 보여준다.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.32-39
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• 2015

최근 펩티드를 포함한 다양한 물질들의 자기조립 (self-assembly) 나노구조체에 대한 연구들이 많이 진행되고 있다. 이는 이러한 분자들로 구성된 구조체들이 환경친화적이며, 생체 나노구조체를 묘사함을 통해 세포소기관의 기능 역시 모방할 수 있다고 기대되기 때문이다. 만약 분자 수준에서 자기조립을 형성하는 단위체를 살펴본다면 자기조립 나노 구조를 개발하는 방법에 대한 통찰을 얻을 수 있을 것이다. 본 연구에서는 최근에 Wen Li 그룹에서 개발한 쉽게 합성할 수 있는 자기조립 펩티드의 적합성을 분자 수준에서 규명하였다. 이를 위해 복제계-맞바꿈 분자 동역학 시뮬레이션 (replica exchange molecular dynamics simulation)을 통해 구조를 샘플링 (sampling)하였고, 얻어진 구조들을 평균 제곱근 편차 (root mean square deviation, RMSD)를 기준으로 클러스터링하였다. 그 결과로 매우 우세한 상대빈도를 보이는 하나의 구조를 얻었으며, 그 구조가 탄소 골격과 잔기의 배열의 측면에서 자기조립 펩티드로 사용되기에 적합함을 규명하였다.

• Proceedings of the KWS Conference
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• v.43
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• pp.278-279
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• 2004

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.54-56
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• 2006