• International Journal of Naval Architecture and Ocean Engineering
• /
• 제11권1호
• /
• pp.553-571
• /
• 2019

Geometric variation including welding distortion accumulates as many parts are joined together, ultimately affecting the final product. This variation is then subjected to correction, which requires considerable effort, time, and cost. This variation can be categorized as in-plane/out-of-plane variation. To date, studies on variation simulation have largely focused on the out-of-plane variation, however the variation generated in the in-plane direction requires more time and efforts to correct afterwards. This research aims to construct a variation simulation model considering both the in-plane and out-of-plane variations. A geometric analysis was performed to derive an equation that reflects the coupling effect of the out-of-plane variation on the in-plane variation. The proposed model is validated with case study analysis and the results shows that good fidelity in predicting and diagnosing the in-plane variation during the block assembly process considering welding distortion.

• Journal of Welding and Joining
• /
• 제32권4호
• /
• pp.69-74
• /
• 2014

Welding distortions of large steel structures had mainly been estimated with some simplified formula obtained by lots of experience and numerical analyses for small steel structures. However, the large structures would have different characteristics of distortion with welding because of their own stiffness coming from the size itself. Therefore, in order to find some measures for preventing welding distortion of large structure, it is requite in advance to precisely analysis thermal stress and distortion during welding of the structure. Numerical analysis for larger structure has been known to take large amount of calculation time and have a poor convergency problem during the thermo-elasto-plastic calculation. In this study, a hybrid method is proposed to analysis the thermal stress and distortion of a large steel plate with the finite element analysis by incorporating with temperature distribution of the plate calculated by an analytical solution. The proposed method revealed that the thermo-mechanical analysis for welding of the large structure could be performed with a good convergence and produced precise results with much reduced time consumption.

• Journal of Welding and Joining
• /
• 제33권1호
• /
• pp.80-86
• /
• 2015

The purpose of this study is to establish the predictive method of the angular distortion caused by the line heating process with high frequency induction heating. In order to do it, the heat input model for the high frequency induction heating system was established through comparing the temperature evaluation results obtained by both FEA and experiment. The critical heating conditions to prevent the degradation of the work piece with various thicknesses were identified by FEA and microstructure test results. Under the critical heating conditions, the extensive line heating tests were performed. According to the test results, it was found that the angular distortion behavior of the heated plates could be defined as the function of heat intensity and the rigidity of heated plate. In addition, it was clarified that the angular distortion strongly depended on the size of test specimen such as the length and the width of the heated plate. Based on these results, the predictive equation for the angular distortion was established with the function of heat intensity, bending rigidity and size of heated plate.

• 복식문화연구
• /
• 제25권6호
• /
• pp.757-772
• /
• 2017

Appearance management is a serious issue for adults and young people in Korean society. People of various ages have used diverse means to improve their appearances. This study focused on dieting as an appearance management behavior in female adolescents. Dieting behaviors are not just a means to improve appearance; they may also relate to individuals' beliefs and self-control. The importance of individual psychological/personality factors cannot, therefore, be ruled out. Such factors can help explain personality factors explain "what causes a compulsive diet and what factors can alleviate it". This study reviewed the literature on perfectionism and self-control as individual personality factors, and empirically examined the effects of these variables on perceived body distortion and dieting behaviors. We performed a structural equation model analysis to verify our hypothesis. The results are as follows: we found perfectionism to be positively related to perceived body distortion and dieting behaviors; we also found self-control to be negatively related to perceived body distortion though unrelated to dieting behaviors; finally, our analysis identified a relationship between perceived body distortion and dieting behaviors. These results indicate that perfectionism and self-control should be considered when conducting guidance and counseling sessions on issues related to dieting behaviors for adolescent' appearance management. This paper concludes by discussing the study's implications and limitations.

• 전자공학회논문지
• /
• 제50권8호
• /
• pp.299-307
• /
• 2013

본 논문에서는 임펄스 방사를 위한 UWB 안테나를 펄스 충실도 및 왜곡율 수식을 유도하고 적용하여 펄스 충실도가 개선된 안테나를 설계하는 방법에 대해 연구하였다. UWB 대역에서 지향성 특성을 갖는 안테나는 낮은 방사손실과, 임펄스 방사왜곡이 최소이어야 한다. 이를 위하여 광대역 임피던스 변환기와 마이크로스트립 슬롯라인 천이부 구조를 갖는 안테나 급전부를 설계하였다. 설계 및 제작된 UWB 안테나는 전파 무반사실에서 방사패턴을 측정하였다. 제작된 UWB 안테나의 임펄스 방사에 의한 펄스충실도는 ${\pm}30^{\circ}$ 빔폭내에서 93%이상의 개선된 결과를 얻었다.

• 대한전자공학회논문지SD
• /
• 제41권4호
• /
• pp.101-112
• /
• 2004

본 논문에서는 3차원 인터커넥트(3D interconnect) 구조를 해석하기 위하여 ADI-유한차분시간영역(ADI-FDTD: Alternating Direction Implicit Finite Difference Time Domain)법으로 맥스웰 회전 방정식(Maxwell's curl equation)을 계산하는 수치 해석 모델을 개발하였고, 개발한 ADI-유한차분시간영역법을 이용하여 3.3 V CMOS 기술로 설계된 샘플러 회로의 일부의 영역에 대해 컴퓨터 모의 실험 결과하여 입력된 구형 전압 신호가 금속 배선을 거치면서 5∼10 ps의 신호 지연과 0.1∼0.2 V의 신호 왜곡이 발생되는 것을 확인하였다. 결론적으로 ADI-유한차분시간영역법을 이용한 풀-웨이브 해석을 통하여 고속의 VLSI 인터커넥트에서의 전자기 현상을 정확하게 분석할 수 있음을 제시하였다.

• 한국통신학회논문지
• /
• 제35권4C호
• /
• pp.408-414
• /
• 2010

CCTV이미지에서 교통정보를 수집하려고 할 때 관측자가 카메라를 움직이면 설치된 검지영역이 손실되고 복원하려고 해도 기계적 오차로인해 어려움을 겪게 된다. 그래서 어안이나 거울을 이용하면 카메라를 움직이지 않아도 된다. 하지만 이러한 상황하에서 가장 큰 문제점은 영상의 왜곡이다. 본 논문에서는 이러한 왜곡을 극복하기 위해 비선형 확산 방정식을 이용한 분할과 이 영역에디포메이션을 적용하여 디블러링 한 후 차량정보 수집을 시도한 결과 이전 결과보다 5% 향상된 결과를 얻었다.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 1999년도 봄 학술발표회 논문집
• /
• pp.327-334
• /
• 1999

Steel box girders are popular to the Practicing engineers for the its large Pure torsional constant. But closed box girders at-e susceptible to the eccentric loading due to the distortion of the cross section. Distorton of the box girder develops the warping normal stress and transverse flexural stress in the cross section and their magnitudes can be large unless internal diaphragms are installed sufficiently. In this study, stiffness matrix and equivalent nodal force vector are formulated on the basis of displacement method. Shape functions are directly derived from the homogeneous solution of the governing differential equation of the distortion. New finite element formulations were coded into a computer program. Several numerical examples were presented to show the validity of developed program.

• 대한기계학회논문집B
• /
• 제20권9호
• /
• pp.2909-2915
• /
• 1996

Precise and accurate pressure measurements are obtained using deadweight piston gauges. Pressure distribution and elastic distortion in the piston-cylinder unit are the leading factors in determination of effective area. The distortion depends upon the pressure distribution in the clearance between piston and cylinder and those are coupled each other. Considering the viscosity pressure relation of oil and governing flow equation in the clearance, a new numerical iterative algorithm is developed. The disagreement between the monotonous and sharp pressure profiles is an indication that the pressure profile will be different for each piston and cylinder unit due to material variances.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
• /
• pp.291-293
• /
• 2005

The purpose of this study is to evaluate the effects of line heating variables for forming the curved plate on the behavior of distortion using FEA and experiment. The optimum mixed ratio and standoff for flame heating was established under the heating conditions given in this study. With the heating condition, the predictive equation of angular distortion and transverse shrinkage was established using FEA and verified by comparing the predicted results and experimental results.