• 암석학회지
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• 제23권2호
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• pp.61-73
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• 2014

소백산육괴의 중앙부에 위치하는 경상북도 북후면-평은면 지역에서 주 구성암류인 선캠브리아기 변성퇴적암류와 중생대 화강암에 대한 변형된 암석 및 미구조 연구를 통하여 (동)북동-(서)남서 방향으로 발달하는 우수 주향 이동성 예천전단대의 상대적인 형성시기, 변형온도, 초압쇄암대의 분포 등을 파악하였다. 연성 변형된 주요 암석구조는 전단변형에 의해 형성된 압쇄구조면과 신장선구조 그리고 편마구조면 내지 압쇄구조면이 습곡되어 형성된 (동)남동-버전스의 완침강-중경사 밀착습곡 등이 있다. 연성전단변형 동안에 형성된 장석들의 특징적인 미구조는 플레임 퍼어사이트, 밀메카이트, 미세단열, 미세킹크, 킹크대, 파동소광 등이 인지된다. 재결정된 석영집합체의 c-축 배열은 rhomb와 basal가 탁월한 미끄럼계로 작용하여 형성된 single girdle과 Type I crossed girdle 형태를 보여준다. 전단운동감각 결정면상에서 인지되는 전단운동감각은 우세한 방향성인 북서-경사와 부수적인 방향성인 남동-경사 압쇄구조면상에서 상부-북동-이동과 상부-남서-이동을 각각 보여준다. 이러한 특징적인 암석 및 미구조로부터 예천전단운동은 밀착습곡이 형성된 이후 발생하였으며, 예천전단운동이 발생할 당시의 변형온도는 $350{\sim}450^{\circ}C$이었음을 알 수 있다. 선캠브리아기 변성퇴적암류의 대상 분포와 변형된 선캠브리아기 변성퇴적암류의 장석과 중생대 화강암의 석영의 입도 분포로부터 불노봉과 박달산 북부를 통과하는 (동)북동 방향의 예천전단대의 초압쇄암대가 설정된다.

• Steel and Composite Structures
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• 제42권4호
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• pp.427-446
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• 2022

Cutouts in the beams or plates are often unavoidable due to inspection, maintenance, ventilation, structural aesthetics purpose, and sometimes to lighten the structures. Therefore, there will be a substantial reduction in the strength of the structure due to the introduction of the cutouts. However, these cutouts can be reinforced with the different patterns of ribs (stiffener) to enhance the strength of the structure. The present study highlights the influence of the elliptical cutout reinforced with a different pattern of ribs on the stability performance of such stiffened composite panels subjected to non-uniform edge loads by employing the Finite element (FE) technique. In the present formulation, a 9-noded heterosis element is used to model the skin, and a 3-noded isoparametric beam element is used to simulate the rib that is attached around a cutout in different patterns. The displacement compatibility condition is employed between the plate and stiffener, and arbitrary orientations are taken care by introducing respective transformation matrices. The effect of shear deformation and rotary inertia are incorporated in the formulation. A new mesh configuration is developed to house the attached ribs around an elliptical cutout with different patterns. Initially, a study is performed on the panels with different stiffener schemes for various ply orientations and for different stiffener depth to width ratios (d_s/b_s) to determine an optimal stiffener configuration. Further, various parametric studies are conducted on an obtained optimal stiffened panel to understand the effect of cutout size, cutout orientation, panel aspect ratio, and boundary conditions. Finally, from the analysis, it can be observed that the arrangement of the stiffener attached to a panel has a major impact on the buckling capacity of the stiffened panel. The stiffener's depth to width ratio also significantly influences the buckling characteristic.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.17-27
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• 2011

본 논문에서는 솔더의 온도 변화에 따른 변형 거동을 평가하기 위하여 솔더 재료의 열변형 거동을 파악할 수 있는 전단시편을 고안하여 온도변화에 따르는 열변형 실험과 유한요소해석을 수행하였다. 전단시편은 열팽창계수가 다른 두 금속 막대와 그 사이 공간에 접합된 솔더로 구성되어 있으며, 솔더는 유연 솔더 (Sn/36Pb/2Ag)와 무연 솔더 (Sn/3.0Ag/0.5Cu) 두가지를 대상으로 하였다. 실시간 무아레 간섭계를 이용하여 세 온도 사이클 동안의 각 온도단계에서 변 위 분포를 나타내는 간섭무늬를 얻고 그로부터 온도에 따른 유연 솔더와 무연 솔더의 열변형 특성을 비교하였다. 유한요소해석을 통하여 여러 연구자가 제시한 솔더의 점소성 물성치를 평가하였으며 유연 솔더의 경우에는 Darveaux가 제안한 Anand 모델, 무연 솔더의 경우 Chang이 제안한 Anand 모델을 사용한 해석 결과가 실험 결과와 가장 일치한다는 것을 밝혔다. 평가된 재료 모델을 사용하여 무연 솔더와 유연 솔더가 포함된 전단시편을 유한요소 해석하고 솔더의 점소성 거동 을 자세하게 분석하였다.

• 대한치과의사협회지
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• 제53권9호
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• pp.644-655
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• 2015

Purpose: This study was conducted to evaluate the effect of the fixture abutment connection type and diameter on the screw joint stability in external butt joint for 2nd surgery and internal cone connected type implant system for 1st and 2nd surgery using ultimate fracture strength. Materials and Methods: USII system, SSII system and GSII system of Osstem Implant were used. Each system used the fixture with two different diameters and cement-retained abutments, and tungsten carbide / carbon coated abutment screws were used. Disc shaped stainless steel metal tube was attached using resin-based temporary cement. The experimental group was divided into seven subgroups, including the platform switching shaped specimen that uses a regular abutment in the fixture with a wide diameter in USII system. A static load was increased to the metal tube at 5mm deviated point from the implant central axis until it reached the compression bending strength at a rate of 1mm/min. Then the deformations and patterns of fracture in threaded connection were compared. Results and Conclusion: 1. In the comparison between the Regular diameter, compression bending strength of SSII system was higher than USII system and GSII system. There was no significant difference between USII system and GSII system. 2. In the comparison between wide diameter, compression bending strength was increased in the order of GSII system, USII system, and SSII system. 3. In comparison between the implant diameter, compression bending strength of the wide diameter was greater than the regular diameter in any system(P<0.05). 4. There was no significant difference between the platform switching (III group) and the regular diameter (I group) in USII system. 5. In USII system, fracture of abutment screw and deformation of both fixture and abutment were observed in I, II and III subgroups. 6. Failure pattern of SSII system, which was the fracture of abutment screw and deformation of the abutment and fixture, was observed in both IV and V subgroups. Fracture of some fixtures was observed in subgroup V. 7. Failure pattern of GSII system, which was the fracture of the abutment screw and deformation of the fixture and the abutment, was observed in both VI and VII subgroups. Apart from other subgroups, subgroup VII demonstrated no bending neither the fracture at the top of the fixture. The compressive deformation of internal slope in the fixture was the only thing observed in subgroup VII.

• 자원환경지질
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• 제15권1호
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• pp.41-47
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• 1982

삼척탄전서부지역(三陟炭田西部地域)의 양단부(兩端部)에 해당하는 본연구지역(本硏究地域)은 태백산통(太白山統)을 기저(基底)로 하여 "조선-평안계(朝鮮-平安系)"의 층서(層序)가 해방전(解放前)에 수립(樹立)되었고 정창희(鄭昌熙)에 의하여 "평안계(平安系)"는 대폭 수정(修正)되었다. 특히 이 지역의 지질구조(地質構造)는 층서확립(層序確立)과 함께 "백운산대향사(白雲山大向斜)"구조(構造)가 이미 오래전에 인지(認知)되었으나 동서성(東西性)의 대습곡구조(大褶曲構造)와 남북성(南北性)의 교차습곡구조(交叉褶曲構造)와의 생성시기(生成時期)의 선후관계(先後關係)에 대해서는 다른 견해(見解)가 대립(對立)되어 왔다. 이 지역(地域)을 대향사(大向斜)의 남익부(南翼部)인 녹전구(碌田區), 북익부(北翼部)인 문곡구(文曲區), 비부(鼻部)인 예미구(禮美區)로 나누어 구조요소(構造要素)를 관측해석(觀測解析)하였던 바, 세 지역의 층이면(層理面)에 대한 ${\pi}$도(圖)에서 얻은 대원(大圓)의 극(極)과 선구조(線構造)의 최대치(最大値)는 비교적 잘 일치하는데 남북성(南北性) 교차습곡(交叉褶曲)의 경향(傾向)과 같다. 이는 남북성교차습곡(南北性交叉褶曲)의 형성과정(形成過程)에서 제구조요소(諸構造要素)가 생성(生成)되었고 동서성대향사(東西性大向斜) 구조(構造)와는 무관(無關)하다는 것을 입증(立證)하므로 선남북성교차습곡후동서성대향사(先南北性交叉褶曲後東西性大向斜)의 습곡작용(褶曲作用)이 있었음을 뒷받침하고 있다. 다시 말하면 본역(本域)에 발달(發達)하는 소구조요소(小構造要素)는 대체로 교차습곡(交叉褶曲)에 수반(隨伴)된 것으로 후기(後期)의 백운산향사(白雲山向斜)에 의해서 담란(擔亂)되고 있다. 기반암층(基盤岩層)에는 동사습곡(同斜褶曲)이, 하부고생층(下部古生層) 중의 규암층중(硅岩層中)에는 심한 단열(斷裂)이, 니질암층(泥質岩層) 중에는 각상습곡(角狀褶曲)이, 탄산염암층(炭酸鹽岩層)중에는 조합벽개(組合劈開)가, 상부고생층(上部古生層)중에는 평행습곡(平行褶曲)이 우세하여 층서(層序)에 따른 변형양식(變形樣式)의 차이(差異)를 보이고 있어 구조계층(構造階層)이 성립(成立)한다.

• Structural Engineering and Mechanics
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• 제11권5호
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• pp.565-574
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• 2001

Experimental investigation into the behaviour of half-scale brick masonry panels were conducted under cyclic loading normal to the bed joint and parallel to the bed joint. For each cycle, full reloading was performed with the cycle peaks coinciding approximately with the envelope curve. Unloading, however, was carried out fully to zero stress level and partially to two different stress levels of 25 percent and 50 percent of peak stress. Stability point limit exhibits a unique stress-strain curve for full unloading but it could not be established for partial unloading. Common point limit was established for all unloading-reloading patterns considered, but its location depends on the stress level at which unloading is carried to. Common point curves were found to follow an exponential formula, while residual strains versus envelope strains can be expressed by a polynomial function of a single term. The relation between residual strain and envelope strain can be used to determine the stress level at which deterioration due to cyclic loading began.

• Coupled systems mechanics
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• 제1권2호
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• pp.115-131
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• 2012

Paper presents an improved solution algorithm based on Finite Element Method to analyse piled raft foundation. Piles are modelled as beam elements with soil springs. Finite element analysis of raft is based on the classical theory of thick plates resting on Winkler foundation that accounts for the transverse shear deformation of the plate. Four node, isoparametric rectangular elements with three degrees of freedom per node are considered in the development of finite element formulation. Independent bilinear shape functions are assumed for displacement and rotational degrees of freedom. Effect of raft thickness, soil modulus and load pattern on the response is considered. Significant improvement in the settlements and moments in the raft is observed.

• Earthquakes and Structures
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• 제5권6호
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• pp.625-655
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• 2013

This paper investigated the seismic behaviour of an innovated non-ductile precast concrete wall structural system; namely HC Precast System (HCPS). The system comprises load-bearing precast wall panels merely connected only to column at both ends. Such study is needed because there is limited research information available in design codes for such structure particularly in regions having low to moderate seismicity threats. Experimentally calibrated numerical model of the wall system was used to carry out nonlinear pushover analyses with various types of lateral loading patterns. Effects of laterally applied single point load (SPL), uniformly distributed load (UDL), modal distributed load (MDL) and triangular distributed load (TDL) onto global behaviour of HCPS were identified. Discussion was focused on structural performance such as ductility, deformability, and effective stiffness of the wall system. Thus, a new method for engineers to estimate the nonlinear deformation of HCPS through linear analysis was proposed.

• 비파괴검사학회지
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• 제6권1호
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• pp.9-22
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• 1986

Acoustic Emission is not only expected as a non-destructive evaluation technique in practice but also noted as a new powerful means of evaluation of materials. AE occurs with plastic deformation and propagation of crack, and this patterns of occurence of AE vary with materials. AE which comes from propagation of crack depends oil the shapes and properties of materials. Like this AE has characteristic of material. The present work is an attempt to evaluate characteristics of carbon steel (SM55C) and Die steel(SKD11) by means of dynamic response of AE method.

• 소성∙가공
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• 제8권4호
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• pp.340-346
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• 1999

Circular drawbead forming and drawing characteristics of CO2 laser welded SPC1 blanks are investigated by experiments and numerical analysis. During the drawbead forming process, the distributions of major strain on upper and lower skins of the specimens are measured. During the drawing process, the drawing forces and the strain distributions are investigated. For the numerical analysis. DYNA3D and SGTAS, a developed rigid-plastic finite-element computer program are used. Numerical results predicted the deformation characteristics well in comparison with experiments. It is concluded that the strains and restraining forces during the forming and the drawing processes show different patterns according to the combination of welded blanks.