• 한국포장학회지
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• 제7권1호
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• pp.9-15
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• 2001

Top-to-bottom compression strength of corrugated fiberboard boxes is partly dependent on the load-carrying ability of the central panel areas. The ability of these central areas to resist bending under load will increase the stacking strength of the box. The difference of box compression strengths, among boxes which are made with identical dimensions and fabricated with same components but different flute sizes, is primarily due to difference of the flexural stiffness of the box panels. Top-to-bottom compression strength of a box is accurately predicted by flexural stiffness measurements and the edge crush test of the combined boards. This study was carried out to analyze the flexural stiffness, maximum bending force and maximum deflection for various corrugated fiberboards by experimental investigation. There were significant differences between the machine direction (MD) and the cross-machine direction (CD) of corrugated fiberboards tested. It was about 50% in SW and DW, and $62%{\sim}74%$ in dual-medium corrugated fiberboards(e.g. DM, DMA and DMB), respectively. There were no significant differences of maximum deflection in machine direction among the tested fiberboards but, in cross direction, DM showed the highest value and followed by SW, DMA, DMB and DW in order. For the corrugated fiberboards tested, flexural stiffness in machine direction is about $29%{\sim}48%$ larger than cross direction, and difference of flexural stiffness between the two direction is the lowest in DMA and DMB.

• Elastomers and Composites
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• 제40권4호
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• pp.258-265
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• 2005

스포츠화 중창용으로 사용되는 PU, IP 및 PH 등 세가지 종류의 발포체를 일정한 응력으로 반복압축한 후, 반복압축에 따른 발포체의 압축력, 영구변형, 회복력 등에 미치는 영향을 고찰하였다. 발포체의 반복압축에 따른 최대압축력은 PU의 경우는 거의 변화하지 않는 것으로 나타났으나 IP의 경우 최대 압축력은 크게 저하되었다. PU는 반복압축에 따른 발포체의 영구변형은 미소하였으나 PH의 경우 반복압축횟수가 증가함에 따라 현저하게 증가하는 경향을 나타내었다. 경도 45인 발포체를 5만회 반복압축 한 경우 발포체의 영구변형은 PU

• 한국식품과학회지
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• 제29권2호
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• pp.266-272
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• 1997

오이, 무우, 마늘 생강 및 감자의 가식부위를 일정크기$({\Phi}\;5\;mm{\times}H\;5\;mm)$로 만든 후, 힘을 가할 때와 제거할 때 발생하는 힘-변형 곡선의 관계로부터 압축 및 비압축 특성을 살펴보고 성분함량 및 세포특성과의 관계를 살펴보았다. 힘을 가하는 초기에 변형의 증가속도가 컸지만 그 이후에는 감소하였으며, 힘을 제거할 때는 압축시와 반대의 결과를 보였다. 9 N에 도달하는 시간과 변형은 감자가 컸으며 마늘이 작았다. 압축 및 비압축시 모든 시료가 분명한 이력현상을 보였으며, 힘(y)과 변형(x)은 y=exp(a+b log(x))의 관계가 있었다. 힘을 가할 때에는 감자가 $3.888{\sim}5.099{\times}10^{-3}\;J$의 많은 일을 하였으며, 그 다음으로는 오이, 무우 순이었으나 힘을 제거할 때에는 마늘이 $2.09{\times}10^{-3}\;J$로 많은 일을 하였다. 비회복성 일은 오이, 무우, 감자가 $76{\sim}96%$이었으며, 마늘이 $36{\sim}42%$로 작았다. 힘을 가할 때 변형은 감자가 컸으며, 마늘이 작았다. 탄성도는 마늘이 압축속도 별로 각각 0.777 및 0.756로 컸으며, 감자와 무우는 $0.301{\sim}0.465$로 작았다. 압축 및 비압축 특성치는 수분함량, 즙액의 점도, 세포의 크기, 조밀도 및 규칙성과 높은 상관이 있었다.

• 대한토목학회논문집
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• 제33권3호
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• pp.1243-1251
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• 2013

본 연구의 목적은 텐션클램프의 초기 체결력이 급곡선 궤도용 탄성레일체결장치의 성능에 미치는 영향을 검토함에 있다. 이를 위해 본 연구에서는 탄성레일체결장치의 구성품 중 텐션클램프의 거동을 평가하기 위해 초기 체결력의 변화와 횡압의 증가를 고려한 실내시험, 현장측정 및 수치해석을 수행하였다. 수치해석 및 실험결과, 초기 체결력의 감소는 텐션클램프에 도입되는 초기 압축응력의 감소로 나타났다. 또한 텐션클램프의 압축응력은 급곡선 궤도에서 발생하는 횡압의 작용에 따라 인장응력으로 변환되는 것으로 나타났다. 따라서 초기 체결력에 의해 텐션클램프에 도입된 압축응력은 외력에 따른 발생 인장응력 저감을 위한 보강력으로 작용하는 것으로 분석되어, 탄성레일체결장치의 장기 내구성능 확보와 안정적인 거동을 유지하기 위해서는 적정 초기 체결력의 확보가 중요한 것으로 나타났다.

• 터널과지하공간
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• 제33권5호
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• pp.339-347
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• 2023

TBM 추진잭이 경사면에 접촉하거나 편심하중이 발생할 때 추진잭의 페데스탈 및 로드 부위에 횡하중에 의한 휨변형이 발생할 수 있다. 이는 추진잭 모듈의 고장을 유발할 우려가 있으므로, 추진잭 모듈 전체에 대한 좌굴 안정성을 검증할 필요가 있다. 본 연구는 추진잭 좌굴 안정성 분석을 위한 좌굴 압축시험방법을 조사하고, 압축시험 시스템을 구성하였다. 추진잭의 전체 부품을 모델링하여 수치해석을 통해 응력집중 파트를 분석하였다. 경사도 0도 조건에서 최대하중을 가압하여 압축시험을 수행하였다. 로드의 변형과 씰의 누유는 관측되지 않아서 0도 조건에서 추진잭의 좌굴 안정성을 검증하였다.

• 한국해양공학회지
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• 제21권6호
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• pp.7-15
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• 2007

A mechanical model was developed to predict the behavior of point-loaded RC slender beams (a/d > 2.5) without stirrups. It is commonly accepted by most researchers that a diagonal tension crack plays a predominant role in the failure mode of these beams, but the failure mechanism of these members is still debatable. In this paper, it was assumed that diagonal tension failure was triggered by the concrete cover splitting due to the dowel action at the initial location of diagonal tension cracks, which propagate from flexural cracks. When concrete cover splitting occurred, the shape of a diagonal tension crack was simultaneously developed, which can be determined from the principal tensile stress trajectory. This fictitious crack rotates onto the crack tip with load increase. During the rotation, all forces acting on the crack (i.e, dowel force of longitudinal bars, vertical component of concrete tensile force, shear force by aggregate interlock, shear force in compression zone) were calculated by considering the kinematical conditions such as crack width or sliding. These forces except for the shear force in the compression zone were uncoupled with respect to crack width and sliding by the proposed constitutive relations for friction along the crack. Uncoupling the shear forces along the crack was aimed at distinguishing each force from the total shear force and clarifying the failure mechanism of RC slender beams without stirrups. In addition, a proposed method deriving the dowel force of longitudinal bars made it possible to predict the secondary shear failure. The proposed model can be used to predict not only the entire behavior of point-loaded RC slender shear beams, but also the ultimate shear strength. The experiments used to validate the proposed model are reported in a companion paper.

• Tribology and Lubricants
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• 제30권6호
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• pp.370-377
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• 2014

The basic elements in a rotary-type scroll compressor are two identical spiral scrolls containing refrigerant gas. The pressure variations in the compression pockets of a scroll compressor change the forces acting on the orbiting scroll, and these forces affect the dynamic behavior of the compression mechanism parts. To achieve high efficiency, using a self-sealing mechanism as a tip seal mechanism is very effective. Tip seals, which are placed on top of the scroll wraps, accomplish thrust sealing. This study calculates the friction force between the tip seal and the side plate of a scroll compressor using the numerical model considered in the Reynolds equation. The calculated friction force is verified by an experiment using a pin-on-disk apparatus. A hydraulic servo valve that controls the pressure of the oil hydraulic cylinder applies the normal load for the test, and a DC servo motor controls the sliding velocity of the disk. The friction force and normal load are measured by the force sensors attached to the supporting parts. The results show that the theoretical and experimental results are similar and that the friction is influenced by the viscosity of the oil and the sliding velocity of the scroll.

• 한국표면공학회지
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• 제51권5호
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• pp.309-315
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• 2018

The purpose of this study is to assess the mechanical properties of the ceramic abutment with washer. In this study, ceramic abutment were used, tested with $30^{\circ}$ compression load, shear fatigue, adaptation accuracy test(rotation angle, contact interval), removal torque force test, torsional breaking force test. The $30^{\circ}$ compression load was 729 N, the shear fatigue load was 275 N, adaptation accuracy test of rotation angle was within $3^{\circ}$, contact interval within $10{\mu}m$, and removal torque force test value is $18.88N{\cdot}cm$, torsional breaking force test value is $35.52N{\cdot}cm$. Ceramic abutment with a washer fitted have sufficient mechanical strength and may be substituted for titanium abutment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.502-505
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• 2007

PMMA has been extensively adopted in Nano Imprint Lithography(NIL). PMMA nano-structures experience severe mechanical load and deformation during NIL process, and understanding its mechanical behavior is very important in designing and optimizing NIL process. One of the most promising techniques for characterizing the mechanical behavior of nano structures is nano pillar compression test. In this study, the mechanical behaviors of PMMA pillars during compression test are analyzed using Molecular Dynamics. Two methods for simulation of PMMA nano pillars are proposed. The stress-strain relationship of nano-scale PMMA structure is obtained based on CVFF(Covalent Valence Force Fields) potential and the dependency of the applied strain rate on the stress-strain relationship is analyzed. The obtained stress-strain relationships can be useful in simulating nano-scale PMMA structures using Finite Element Method(FEM) and understanding the experimental results obtained by compression test of PMMA nano pillars.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.98-105
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• 1997

The behaviour of alloys in the semi-solid state strongly depends on the imposed stress state and on the morphology of the phase which can very from dendritic to globular. The estimation of behaviour characteristic in the compression simulation with seim-solid materials are calculated by finite element method with proposed algorithm. The proposed theoretical model and a various boundary conditions for compression process is investigated with the coupling calculation between the liquid phase flow and the solid phase deformation. The simulation process considering soldification phenomena is performed to the isothermal conditions of two dimensional problems. To analysis of compression process by using semi-solid materials, a new stress-strain relationship is described, and compression analysis is performed by viscoelastic model for the solid phase and the Darcy's law for the liquid flow. The calculated results for compression force and ram displacement will be compared to experimental data.