• Journal of Welding and Joining
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• 제27권3호
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• pp.44-51
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• 2009

In this study, welding distortion analysis is performed for various design of tube shape structures which are assembled with aluminum sheet metal. Aluminum 5052 plates of 1mm thickness are used to analyze. An efficient keyhole model, as a welding heat source, is used for the prediction of full penetration weld size and shape which is required for the thermal analysis. The thermal and mechanical material properties are considered as temperature dependent functions, due to the high temperature variations during the welding. The numerical model is calculated by using a commercial software and evaluated with the experiments. The calculation results could make a comparative study in the view of distortion for the various size and shape of structure.

• 대한조선학회 특별논문집
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• 대한조선학회 2007년도 특별논문집
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• pp.22-25
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• 2007

Angular distortion in welding process is decided by the various variables. We can make the prediction of welding distortion in similar reality by the analysis of data through many specimen tests. However it is difficult that prediction of welding distortion applies to the ship building. We can establish that angular distortion varies directly as the specimen size. And, it makes clear distortion's difference between constraint and unconstraint, according to the change of a plate thickness.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2006년 추계학술발표대회 개요집
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• pp.280-282
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• 2006

Prediction and control of the thermal distortion is particularly important for the design and manufacture of welded thin plate panel. In this study, experiments and computations are peformed to analyze how hole configuration and the size of the specimen effect on distortion. In addition, this study aims to develop a thermal elasto-plastic simulation using finite element method to predict distortion, with particular emphasis on buckling deformation generated in attachments welded around hole.

• International Journal of Ocean System Engineering
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• 제3권2호
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• pp.95-101
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• 2013

This study is mainly interested in roundness of a circular moonpool structure in FPSO. Because this structure needs abrasion-resistance on inner wall, we should do buttering widely and deeply by using Inconel. But a general buttering can cause a severe distortion at structures. If someone can analyze the roundness by thermal distortion under Inconel over-lay, an erection policy can be established. In this study, shrinkage methodology by designed stress-strain curve was used and the result allowed deciding an appropriate block size.

• 디지털융복합연구
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• 제17권6호
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• pp.365-371
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• 2019

본 연구는 예술적 장르인 르네마그리트의 초현실주의 작품 레슬러의 무덤의 소재인 장미를 모티브로 활용하여 VR콘텐츠를 제작하였다. 현재 시장은 VR콘텐츠의 대중화로써 게임, 체험형 전시로 활성화 되고 있다. VR콘텐츠의 문제점은 관람자에게 게임, 단순 체험형 전시보다 예술적 장르인 콘텐츠 개발이 필요하다. 데페이즈망 기법을 공간의 변조(왜곡), 모순된 이미지의 결합(중첩), 물체의 변형과 변화(스케일) 3가지 키워드로 분류하고 프랙탈 구조의 왜곡, 중첩, 스케일의 3D 착시 패턴을 데페이즈망에 대입하였고, 이미지스케일 도구를 활용하여 장미를 대입하였다. 결론으로 이미지 스케일의 왜곡(공간의 변조)은 Dynamic-curve, Texture-soft 영역에 연결하였고, 중첩(모순된 이미지의 결합)은 Big-size, Irregular-depth영역, 스케일(물체의 변형과 변화)은 big-size, Irregular-space영역의 포지션에 연결하였다. 타임라인별 방안에 식물과 장미패턴을 제작하여 Overlap, Scale, Distortion, Overlap, Distortion, Scale 순으로 진행이 되었고, 착시효과의 다양성을 활용하여 문제점을 보완하였다. 본 연구를 바탕으로 인지적, 물리적, 기능적, 감각적 어포던스 오감을 활용한 완성도 높은 예술적 VR 영상 콘텐츠를 제작할수 있을것으로 기대한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.2065-2069
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• 2004

This paper presents an adaptive equalizer using finite impulse response (FIR) filter and least-mean square (LMS) algorithm. Herein, the variable step-size technique (VSLMS) for compensating the amplitude of chrominance signal is utilized. The proposed equalizer can be enhanced and compressed the chrominance signal at color subcarrier. The LMS algorithm employed in simplicity structure but gives slow convergence speed. Thus, the variable step-size is very attractive algorithm due to its computational efficiencies and the speed of convergence is improved. In addition, experimental results are carried out by using the modulated 20T sine squared test signal. It is shown here that the adaptive equalizer can be equalized the amplitude chrominance distortion in color television transmission without relative delay distortion.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 제14회 신호처리 합동 학술대회 논문집
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• pp.605-608
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• 2001

This paper proposes LUT based predistorter using interpolater to reduce nonlinear distortion which was generated by HPA. We minimized performance degradation from the reduced LUT size with linear interpolation. We updated LUT using LMS algorithm using input data as reference data. As a result, it is shown that when the size of the LUT is 8, linear interpolation is the most outstanding performance in the view of performance and H/W complexity.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(1)
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• pp.153-156
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• 2002

An adaptive predistorr is proposed to compensate for the nonlinear distortion of a high power amplifier (HPA) in 16 QAM system. It fumed out that the proposed predistorter using a variable step-size least mean square (VSSLMS) algorithm is stable and can reduce the Total Distortion (TD) to 0. 1dB at the HPA output backoff=0.0 dB.

• Journal of Advanced Research in Ocean Engineering
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• 제1권2호
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• pp.106-114
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• 2015

In the fabrication of offshore oil and gas facilities, the significance of dimension control is growing continuously. But, it is difficult to determine the deformation of the structure during fabrication by simple lab tests due to the large size and the complicated shape. Strain-boundary method (a kind of shrinkage method) based on the shell element was proposed to predict the welding distortion of a structure effectively. Modeling of weld geometry in shell element is still a difficult task. In this paper, a concept of imaginary temperature pair is introduced to handle the effect of geometric factors such as groove shape, plate thickness and pass number, etc. Single pass imaginary temperature pair formula is derived from the relation between the groove area and the FE mesh size. By considering the contribution of each weld layer to the whole weldment, multi-pass imaginary temperature is also derived. Since the temperature difference represents the distortion increment, cumulative distortion curve can be drawn by integrating the temperature difference. This curve will be a useful solution when engineers meet some problems occurred in the shipyard. A typical example is shown about utilization of this curve. Several verifications are conducted to examine the validity of the proposed methodology. The applicability of the model is also demonstrated by applying it to the fabrication process of the heavy ship block. It is expected that the imaginary temperature model can effectively solve the modeling problem in shell element. It is also expected that the cumulative distortion curve derived from the imaginary temperature can offer useful qualitative information about angular distortion without FE analysis.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2004년도 추계학술발표대회 개요집
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• pp.254-256
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• 2004

The purpose of this study is to establish the control method of angular distortion at the weldment of the pressure hull penetration. In order to do it, comprehensive experiment and FEA were performed to evaluate the distortion behavior for the weldment of HY-100. Based on the results, a proper deposit sequence for the both sides X groove penetration weldment was established. In addition, a proper welding sequence was proposed by evaluation of bending restraint intensity with size and position of pressure hull penetration.