• 한국기계가공학회지
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• 제8권1호
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• pp.64-70
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• 2009

This study is to analyze the impact of automotive body with computer simulation. The total deformation, equivalent strain and strain and principal stress are analyzed respectively in case of front, rear and side impacts. The maximum total deformation of side impact is more than 6 times as large as that of rear impact. The maximum equivalent strain or stress of side impact is more than 4 times as large as that of rear impact. These deformation, strain and stress of front impact are a little more than those of rear impact. The maximum principal stress of side impact is more than 4.5 times as large as that of rear impact. This stress of front impact is a little more than that of rear impact.

• 화약ㆍ발파
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• 제32권3호
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• pp.10-17
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• 2014

본 연구에서는 2자유면을 가진 암반의 장공발파 시 천공간격과 뇌관의 기폭시차에 따라 발생되는 내부주변형률의 변화를 확인하기 위하여 Visual FEA 유한요소 프로그램으로 해석 암반의 단면을 모델링하여 인접공균열권 내의 주요 절점에서 최대주변형률을 분석하였다. 결과적으로, 장공발파 시 천공간격이 좁고 기폭시차가 길수록 인접공 균열권 내에 미치는 최대주변형률 값이 크게 나타났고, 장약장 내 폭약의 기폭 위치에 따라 최대 주변형률의 차이를 보였다.

• 화약ㆍ발파
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• 제35권4호
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• pp.10-18
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• 2017

본 연구에서는 도심지 분할 발파 시 인공적으로 분리되는 절취면에서의 변형을 확인하기 위해 Visual FEA 유한요소 프로그램으로 발파 단면을 모델링하여 기폭 패턴에 따른 최대주변형률을 분석하고, 절취면에서 시간 영역에 따른 최대주변형률을 비교하였다. 결과적으로, 기폭 패턴에 따라 암반 절취면에서 최대주변형률의 차이를 보였고, 분할 발파에서 기폭 시차가 중요한 변수로 작용하고 있음을 확인하였다.

• 화약ㆍ발파
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• 제37권2호
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• pp.1-13
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• 2019

본 연구에서는 도심지 발파에서 형성되는 분할 단면의 변형을 확인하기 위해 Visual FEA 유한요소 프로그램으로 발파 단면을 모델링하여 발파 기폭 패턴에 따른 최대주변형률을 분석하였고, Visual FEA 유한요소 프로그램으로 분석된 분할 단면과 현장 발파로 형성된 분할 단면을 비교하였다. 결과적으로, 발파 기폭 패턴에 따라 분할 단면에서 최대주변형률의 차이를 나타냈고, 전산해석과 현장 발파에서 분할 단면이 유사한 파형 형태를 보이는 것으로 확인되었다.

• 펄프종이기술
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• 제31권5호
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• pp.73-85
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• 1999

Yield and fracture are separated in the tensile failure of paper. Failure in the machine direction of photocopy paper is contrasted with failure in the cross-machine direction . The ratios of distortion (shape change) to dilatation (volume change) for individual elements at yield and fracture are described. The ratios of distortion to dilatation are measured and compared to predicted values of the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density theory. To evaluate the effect of the angle from the principal material direction on the strain energy density factor, samples are prepared from machine direction to cross-machine direction in 15 degree intervals. the strain energy density of individual elements are obtained by the integration of stress from finite element analysis with elastic plus plastic strain energy density theory. Poison's ratio and the angle from the principal material direction have a great effect ion the ratio fo distortion to dilatation in paper. During the yield condition, distortion prevails over dilatation . At fracture, dilatation is at a maximum.

• Korean Journal of Geomatics
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• 제3권2호
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• pp.141-148
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• 2004

This paper deals with the characteristics of strain pattern by using permanent GPS stations in Korea in terms of seismic activity and tectonics. Fourteen GPS stations involved in precise baseline vector solution and horizontal strain components were calculated using the differences of mean baseline from ten deily solutions during the time span of three years. The mean rate of maximum shear strain if 0.12 $\mu$/yr. The mean direction of principal axes of the compression is about $85^{\circ}$ N.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 춘계학술대회 논문집
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• pp.268-273
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• 1992

Thin walled tubular specimens of 0.45% structural carbon steel were used in the bizxial tests. Biaxial fatigue tosts were conducted on strain control including fully reversed tension-compression and in phase tension torsion loadings. The predictions of the biaxial fatigue life were based upon the uniaxial low cycle fatigue test results. Fatigue lives were ranged from 10$\^$2/to 10$\^$5/cycles. Four multiaxial strain based theories have been developed to correlate biaxial fatigue experimdntal results. These theories showed good correlatins except for maximum shear strain theory. In uniaxial tests, crack behavior was observed that crack initiated in the maximum shear strain direction and propagated in the direction perpendicular to principal stross. But, in biaxial tests, both crack initiation and growth occured on the maximum shear strain direction only.

• Elastomers and Composites
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• 제38권4호
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• pp.354-362
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• 2003

The use of a petaloid design for the bottom of carbonated poly(ethylene terephthalate)(PET) bottles is widely spread. This study investigated the causes of bottom cracks. The tensile yield stress variations of PET according to the crystallinity and stretch ratio were examined, then the stretch ratio and strength in the bottom area of a blown bottle were analyzed. A crack test was also performed to observe the cracking phenomena. The distribution of the effective stress and maximum principal stress were both examined using computer simulation to seek the influence of the bottom design on crack. It was concluded that the bottom cracks occurred because of inadequate material strength due to the insufficient stretching of PET, plus the coarse design of a petaloid bottom. The stretch ratio at the bottom during bottle blowing should be higher than the strain hardening point of PET to produce enhanced mechanical strength. The cracks in the bottom of the PET bottles occurred through crazing below the yield stress. The maximum principal stress was higher in the valleys of the petaloid bottom than in the rest bottom area, and the maximum principal stress had a strong effect on the cracks.

• Structural Engineering and Mechanics
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• 제47권4호
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• pp.531-544
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• 2013

Compared with pavement structures of ordinary road sections, pavement structures in the intersection are exposed to more complex traffic characteristics which may exacerbates pavement distresses such as fatigue-cracking, shoving, shear deformation and rutting. Based on a field survey about traffic characteristics in the intersection conducted in Shanghai China, a three dimensional dynamic finite-element model was developed for evaluating the mechanistic responses in the pavement structures under different traffic characteristics, namely uniform speed, acceleration and deceleration. The results from this study indicated that : (1) traffic characteristics have significant effects on the distributions of the maximum principal strain (MPS) and the maximum shear stress (MSS) at the pavement surface; (2) vehicle acceleration or deceleration substantially impact the MPS and MSS at pavement surface and could increase the magnitude of them by 20 percent to 260 percent; (3) in the vertical direction, with the increase of vehicle deceleration rate, the location of the MPS peak value and the MSS peak value changes from the sub-surface layer to the pavement surface.

• Journal of Periodontal and Implant Science
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• 제46권3호
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• pp.152-165
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• 2016

Purpose: This study investigated the effects of bone density and crestal cortical bone thickness at the implant-placement site on micromotion (relative displacement between the implant and bone) and the peri-implant bone strain distribution under immediate-loading conditions. Methods: A three-dimensional finite element model of the posterior mandible with an implant was constructed. Various bone parameters were simulated, including low or high cancellous bone density, low or high crestal cortical bone density, and crestal cortical bone thicknesses ranging from 0.5 to 2.5 mm. Delayed- and immediate-loading conditions were simulated. A buccolingual oblique load of 200 N was applied to the top of the abutment. Results: The maximum extent of micromotion was approximately $100{\mu}m$ in the low-density cancellous bone models, whereas it was under $30{\mu}m$ in the high-density cancellous bone models. Crestal cortical bone thickness significantly affected the maximum micromotion in the low-density cancellous bone models. The minimum principal strain in the peri-implant cortical bone was affected by the density of the crestal cortical bone and cancellous bone to the same degree for both delayed and immediate loading. In the low-density cancellous bone models under immediate loading, the minimum principal strain in the peri-implant cortical bone decreased with an increase in crestal cortical bone thickness. Conclusions: Cancellous bone density may be a critical factor for avoiding excessive micromotion in immediately loaded implants. Crestal cortical bone thickness significantly affected the maximum extent of micromotion and peri-implant bone strain in simulations of low-density cancellous bone under immediate loading.