• 항공우주시스템공학회지
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• 제16권6호
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• pp.8-17
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• 2022

항공기 날개에 사용되는 스킨-스트링거 패널은 기계적 체결과 접착 체결로 인하여 응력 집중과 접착 분리가 발생할 수 있다. 이를 고려하여, 3차원 직조 복합재료를 이용해 스킨과 스트링거를 일체시킨 패널을 설계하였다. 본 논문에서는 일체형 패널의 기계적 물성을 예측하기 위하여 기하학적 모델링 기법을 제안하였다. 시편의 기하학적 변수를 측정하고 섬유 다발의 패턴을 함수식으로 정의해 기하학적 모델링을 수행하였다. 이를 검증하기 위하여 iso-strain, iso-stress 가정을 사용한 가중평균모델을 통해 각 부재의 기계적 물성을 예측하고 유한요소해석을 수행해 압축시험 결과와 비교하였다. 제안한 기하학적 모델링 기법을 통해 스킨-스트링거 일체형 패널의 기계적 물성을 실험적 방법보다 효율적으로 예측하였다.

• 대한조선학회 특별논문집
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• 대한조선학회 2009년도 특별논문집
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• pp.52-58
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• 2009

Openings for access to cargo holds are cut on horizontal stringers in every bulkhead of container carriers. But, they are positioned at the edge of stringer width to make minimum space for access and these openings are required to be stiffened by owners and classifications respectively. In this paper, the cargo hold bulkhead stringers with openings for 6,500 TUE container carriers were reviewed by FE analysis to be conducted with the results of hold analysis for 6,500 TUE container carriers classed to GL, DNV, LR and BV respectively, and purpose of this paper is to establish yard's standard of the reinforcement for these openings.

• 대한기계학회논문집A
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• 제20권7호
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• pp.2223-2233
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• 1996

The analytical solutions for the free vibration of cross-ply laminated composite cyllindrical shell with axial stiffeners(stringers) are presented usint the energy method. The stiffeners are taken to be smeared over the surface of shell with the smeared stffener theory. The effect of the parameters such as the stacking sequences, the shell thichness, the shell radius-to stringer depth ratio, the stringer depth-to width ratio, the shell length-to radius ratio are studied. By comparison with the previously published experimental results and the analytical results for the stiffened isotropic cylindrical shell and the unstiffened orthotropic composite laminated cylindrical shell, it is shown that natural frequencies can be determined with adequate accuracy.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 추계학술대회 논문집
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• pp.201-206
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• 2007

In this paper, we apply a three-dimensional rigid-plastic finite element method to simulate an unsteady-state roll forming process. A typical roll forming process is investigated from the standpoint of computer simulation and its realistic analysis model is proposed. The material is considered as bulk material and discretized into hexahedral finite elements. The presented approach is applied to simulating the roll forming process of straight stringer used for aircraft structure.

• Transactions on Electrical and Electronic Materials
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• 제10권6호
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• pp.189-192
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• 2009

The leakage current in a CMOS image sensor (CIS) can have various origins. Leakage current investigations have focused on such things as cobalt-salicide, source and drain scheme, and shallow trench isolation (STI) profile. However, there have been few papers examining the effects on leakage current of nitride stringers that are formed by gate sidewall etching. So this study reports the results of a series of experiments on the effects of a nitride stringer on real display images. Different step heights were fabricated during a STI chemical mechanical polishing process to form different nitride stringer sizes, arsenic and boron were implanted in each fabricated photodiode, and the doping density profiles were analyzed. Electrons that moved onto the silicon surface caused the dark leakage current, which in turn brought up the speckle defect on the display image in the CIS.

• 항공우주시스템공학회지
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• 제14권6호
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• pp.68-73
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• 2020

Skin-stringer structures are widely used in aircrafts due to their advantage of minimizing structural weight while maintaining load carrying capacity. However, buckling load can cause serious damage to these structures. Therefore, the buckling characteristics of skin-stringer structures should be carefully considered during the design phase to ensure structural soundness. In this study, finite element method was applied to predict the buckling characteristics of stiffened panels. In terms of the failure mode, finite element analysis showed a symmetrical buckling mode, whereas an asymmetrical mode was determined by experimentation. The numerical results were obtained and compared to the experimental data, showing a difference of 9.3% with regard to the buckling loads.

• Animal Systematics, Evolution and Diversity
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• 제26권2호
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• pp.153-156
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• 2010

Two species of Yponomeutinae new to Korea, Euhyponomeutoides trachydeltus (Meyrick) and Thecobathra anas (Stringer), are reported. In addition, occurrence of Yponomeuta anatolicus (Stringer) in Korea is confirmed with proper collection of data. The adults and genitalia for the three species are illustrated.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2008년도 제35회 하계학술대회 초록집
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• pp.325-326
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• 2008

• Structural Engineering and Mechanics
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• 제62권6호
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• pp.719-724
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• 2017

We consider an elastic isotropic plate reinforced by stringers and weakened by a periodic system of rectilinear slots of variable width. The variable width of the slots is comparable with elastic deformations. We study the case when the slots faces get in contact at some area. Determination of parameters characterizing the partial closure of variable width slots is reduced to the solution of a singular integral equation. The action of the stringers is replaced with unknown equivalent concentrated forces at the points of their connection with the plate. The contact stresses and contact zone sizes are found from the solution of the singular integral equation.

• 한국강구조학회 논문집
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• 제16권5호통권72호
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• pp.713-724
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• 2004

거동이 복잡한 실제 구조물의 사용하중으로 인한 피로 균열 해석 방법을 제시하기 위해 구 당산철교 플레이트교 세로보에 발생한 피로균열을 대상으로 하여 사용 기간에 따른 피로균열의 길이를 계산하였다. 계산의 편리와 컴퓨터의 계산 용량 등을 고려하여 특정 부분만 정밀하게 해석하였고, 구조해석의 오차와 열차의 운행 하중 등을 고려하기 위해 여러 보정계수를 사용하였다. 상부구조 1개 경간을 보요소로 모델링하여 열차 통과로 인한 세로보의 거동 이력을 해석하였으며, 세로보 연결부의 플랜지가 절취된 곳에 집중된 응력을 구하기 위하여 세로보 한 개를 쉘요소로 모델링하여 정밀해석을 수행하였다. 피로균열의 진행은 파괴역학적 모델을 사용하여 계산하였으며, 응력확대계수는 유한요소해석 방법으로 J-Integral를 구하여 환산한 값을 사용하였다. 가정한 초기균열의 크기와 균열 진행속도 계산식에 따라 차이는 있으나 계산된 피로균열의 길이는 현장에서 조사된 피로균열길이에 잘 부합되는 것으로 나타났다.