• Structural Engineering and Mechanics
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• 제43권2호
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• pp.253-271
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• 2012

To analyze the bending and transverse shear effects of laminated composite plates, a thirteen nodes triangular element will be presented. The suggested formulations consider a parabolic variation of the transverse shear strains through the thickness. As a result, there is no need to use shear correction coefficients in computing the shear stresses. The proposed element can model both thin and thick plates without any problems, such as shear locking and spurious modes. Moreover, the effectiveness of $w_{,n}$, as an independent degree of freedom, is concluded by the present study. To perform the accuracy tests, several examples will be solved. Numerical results for the orthotropic materials with different boundary conditions, shapes, number of layers, thickness ratios and fiber orientations will be presented. The suggested element calculates the deflections and stresses more accurate than those available in the literature.

• 한국지진공학회논문집
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• 제16권2호
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• pp.25-33
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• 2012

본 연구에서는 내력벽 시스템에 대하여 연결보의 단부에 적용이 가능한 박판형 금속감쇠기의 성능을 실험을 통하여 규명하고자 하였다. 박판형 금속감쇠기의 박판 두께와 길이를 변수로 하여 5개 시험체를 제작하였으며, 층간변위비 5%까지 반복하여 횡력을 가력하였다. 실험결과, 금속 박판에 좌굴발생 후 소성변형이 발생하면서 에너지 발산이 이루어졌으며, 기존의 일반 콘크리트 시험체보다 에너지 발산량이 크게 나타났다. 박판의 길이가 짧을수록 전단내력의 값은 증가하였으나 발산에너지의 양의 증가는 크게 나타나지 않았다. 실험 내력을 탄성좌굴해석과 비교한 결과, 해석에 의한 내력은 내력곡선 선형영역의 최대값을 적절히 예측함을 알 수 있었다.

• 대한조선학회논문집
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• 제33권3호
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• pp.66-80
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• 1996

최근 고장력강(高張力鋼)이 구조물에 폭넓게 사용되고 있어서 판두께가 얇아지고 있다. 판두께가 얇아지므로해서 좌굴(座屈)이 발생하기 쉽다. 그러므로 좌굴(座屈)발생후 판의 거동(擧動)을 정확하게 파악하는 것은 중요하다. 좌굴(座屈) 발생후 2차좌굴(次座屈)이라고 하는 하중하(荷重下)에서는 판(板)의 처짐모드가 갑자기 변한다. 전체구조물의 붕괴강도(崩壞强度)를 고려할 때 2차좌굴(次座屈)은 매우 중요하다. 이런 관점에서 본 연구에서는 면내압축하중(面內壓縮荷重)을 받는 판(板)의 2차좌굴거동(次座屈擧動)에 관하여 연구하였다. 초기처짐을 갖는 판(板)을 대상으로 하여 탄성대변형해석(彈性大變形解析)을 실시하여, 2차좌굴(次座屈)의 영향을 검토하였다. 그 결과로서 다음과 같은 결론(結論)을 얻었다. 즉, 정사각형판은 대칭의 처짐성분은 영향이 있으나 비대칭의 처짐성분은 영향이 전혀 없다. 또한, 종횡비(縱橫比)를 갖는 판(板)은 모든 처짐성분의 영향이 있으며 초기좌굴(初期座屈)후 면내강성(面內剛性)이 계속적으로 감소한다.

• Steel and Composite Structures
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• 제44권5호
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• pp.633-649
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• 2022

This paper is first implemented with the bending behavior of three-dimensional functionally graded (3DFG) plates in the framework of level set-based topology optimization (LS-based TO). Besides, due to the suitable properties of the current design domain, the thin-plate spline (TPS) is recognized as a RBF to construct the LS function. The overall mechanical properties of the 3DFG plate are assessed using a power-law distribution scheme via Mori-Tanaka micromechanical material model. The bending response is obtained using the first-order shear deformation theory (FSDT). The mixed interpolation of four elements of tensorial components (MITC4) is also implemented to overcome a well-known shear locking problem when the thickness becomes thinner. The Hamilton-Jacobi method is utilized in each iteration to enforce the necessary boundary conditions. The mathematical formulas are expressed in great detail for the LS-based TO using 3DFG materials. Several numerical examples are exhibited to verify the efficiency and reliability of the current methodology with the previously reported literature. Finally, the influences of FG materials in the optimized design are explained in detail to illustrate the behaviors of optimized structures.

• Structural Engineering and Mechanics
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• 제18권1호
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• pp.79-90
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• 2004

A high precision shear deformable triangular element has been proposed for bending analysis of triangular plate. The element has twelve nodes at the three sides and four nodes inside the element. Initially the element has thirty-five degrees of freedom, which has been reduced to thirty by eliminating the degrees of freedom of the internal nodes through static condensation. Plates having different boundary conditions, side ratios (b/a) and thickness ratios (h/a = 0.001, 0.1 and 0.2) have been analyzed using the proposed shear locking free element. Concentrated and uniformly distributed transverse loads have been used for the analysis. The formulation is made based on first order shear deformation theory. For validation of the present element and formulation few results of thin triangular plate have been compared with the analytical solutions. Results for thick plate have been presented as new results.

• 한국안전학회지
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• 제32권5호
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• pp.69-75
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• 2017

Structural safety evaluation for static strength of thin plate RC member with high strength concrete is conducted in this study. Static strengths were predicted and compared with the experimental values. Predicted values were calculated by the evaluation formula based on the punching shear behavior and the yield line theory which can appear in the plate members. Static load tests were carried out for the specimens with high strength concrete and the test results were compared with the required performance in design. The comparison results show that the specimens with high strength concrete have sufficient structural safety for flexural and punching shear performance required in design. High strength concrete specimens exhibited excellent strength despite their small thickness. The range of concrete strengths applied in this study was about 60 MPa to 100 MPa.

• 한국공간구조학회논문집
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• 제1권1호
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• pp.109-115
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• 2001

Composite materials also known as fiber reinforced plastics have been developed and used in many engineering applications due to their outstanding mechanical properties. Laminated plates as structural components that are made of in composite material are widely used. Therefore, nonlinear response of laminated composite plates modeled with finite elements and excited by stochastic loading is studied. The classical laminated plate theory is used to account for the variation of strains through the thickness for modeling laminated thin plates. Approximate nonlinear random vibration analysis is performed using the method of equivalent linearization to account for material non-linearity.

• Journal of Periodontal and Implant Science
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• 제41권2호
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• pp.60-66
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• 2011

Purpose: The aim of this study is to evaluate the buccal and lingual bone thickness in the anterior teeth and the relationship between bone thickness and the tissue biotype. Methods: Three male and two female human cadaver heads (mean age, 55.4 years) were used in this study. First, the biotype of periodontium was evaluated and categorized into a thick or a thin group. Next, full thickness reflections of the mandible and the maxilla to expose the underlying bone for accurate measurements in the anterior regions were performed. After the removal of the half of the alveolar bone, the probe with a stopper was used to measure the thickness of bone plate at the alveolar crest (AC), 3 mm apical to the alveolar crest (AC-3), 6 mm apical to the alveolar crest (AC-6), and 9 mm apical to the alveolar crest (AC-9). The thickness of the buccal plates at the alveolar crest were $0.97{\pm}0.18\;mm$,$0.78{\pm}0.21\;mm$, and $0.95{\pm}0.35\;mm$ in the maxillary central incisors, lateral incisors, and canines, respectively. The thickness of the labial plates at the alveolar crest were $0.86{\pm}0.59\;mm$, $0.88{\pm}0.70\;mm$, and $1.17{\pm}0.70\;mm$ in the mandibular central incisors, lateral incisors and canines, respectively. Conclusions: The thickness of the labial plate in the maxillary anteriors is very thin that great caution is needed for placing an implant. The present study showed the bone thickness of maxillary and mandibular anteriors at different positions. Therefore, these data can be useful for the understanding of the bone thickness of the anteriors and a successful implant placement.

• Ocean and Polar Research
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• 제27권1호
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• pp.35-44
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• 2005

The bathymetric and gravity data were obtained in 2001 and 2003 during a survey of seamounts in the northwest of the Marshall Islands, western Pacific. The study areas are located in the Pigafetta Basin which is the oldest part of the Pacific plate and in the Ogasawara Fracture Zone which formed from the spreading ridge between the Izanagi and Pacific plates in the Jurassic. The densities of seamounts and the elastic thickness values of the lithosphere are calculated by using three-dimensional flexure modeling considering the constant sediment layer in the infinite plate model. Very low elastic thickness values (5km), relatively young seamounts, and old lithosphere in the east study area suggest the possibility of the rejuvenation of lithosphere by widespread volcanisms, whereas the elastic thickness values (15km), relatively old seamounts, and young lithosphere of the west study area are suitable for a simple cooling plate model of $300-600^{\circ}C$ isotherm. The gravity residuals of OSM6-1 and OSM6-2 suggest the possibility of different load density or elastic thickness. Relatively older OSM6-2 formed on the younger lithosphere with relatively thin elastic thickness, while younger OSM6-1 on the older lithosphere with relatively thick elastic thickness.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.422-425
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• 2008

Recently, electronic products and related parts are required to have thin thickness because of small form factor. To go with the trend, LGP(light guide plate) of LCD BLU(Liquid Crystal Display Back light unit: It is one of kernel parts of LCD) for cell phone has the thickness of 0.3 mm and the battery case of cell phone has 0.25 mm. Accordingly, high speed injection molding is required to make products which have thin thickness. High speed injection molding means that the resin is injected into the cavity at higher than normal speed avoiding short shot. In the case of hydro-mechanical high speed injection machine, it requires the design for hydraulic unit to make high injection speed and the design for control unit to control hydraulic unit. In the present paper, we concentrated on the molding stability of hydro-mechanical high speed injection machine to make an LGP of 0.3 mm thickness.