• Steel and Composite Structures
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• 제38권5호
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• pp.583-597
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• 2021

This article develops a nonclassical model to analyze bending response of squared perforated microbeams considering the coupled effect of microstructure and surface stress under different loading and boundary conditions, those are not be studied before. The corresponding material and geometrical characteristics of regularly squared perforated beams relative to fully filled beam are obtained analytically. The modified couple stress and the modified Gurtin-Murdoch surface elasticity models are adopted to incorporate the microstructure as well as the surface energy effects. The differential equations of equilibrium including the Poisson's effect are derived based on minimum potential energy. Exact closed form solution is obtained for bending behavior of the proposed model considering the classical and nonclassical boundary conditions for both uniformly distributed and concentrated loads. The proposed model is verified with results available in the literature. Influences of the microstructure length scale parameter, surface energy, beam thickness, boundary and loading conditions on the bending behavior of perforated microbeams are investigated. It is observed that microstructure and surface parameters are vital in investigation of the bending behavior of perforated microbeams. The obtained results are supportive for the design, analysis and manufacturing of perforated nanobeams that commonly used in nanoactuators, nanoswitches, MEMS and NEMS systems.

• 한국콘텐츠학회논문지
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• 제16권3호
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• pp.376-390
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• 2016

본 연구의 목적은 제주지역 소상공인을 대상으로 소상공인의 커뮤니케이션 능력과 고객지향적 행동의 관계에서 감정노동(표면조절, 심층조절)의 매개효과를 검증하고자 한다. 구체적으로 커뮤니케이션 능력의 고객지향적 행동 및 감정노동(표면조절, 심층조절)에 대한 영향력 관계, 감정노동(표면조절, 심층조절)의 고객지향적 행동의 주효과, 그리고 커뮤니케이션 능력과 고객지향적 행동의 관계에서 감정노동(표면조절, 심층조절)의 매개효과 검증이다. 분석에 활용된 자료는 제주지역의 소상공인 270명으로부터 획득된 자료를 활용하였다. 분석결과, 소상공인 커뮤니케이션 능력은 고객지향적 행동 및 감정노동에 영향을 미치고, 감정노동 가운데 표면조절만이 고객지향적 행동에 영향력이 있으며, 표면조절은 양자관계를 부분 매개하는 것으로 나타났다. 이러한 결과는 소상공인 커뮤니케이션 능력이 서비스접점에서 주요한 능력임을 입증하는 것이며, 서비스 제공자의 커뮤니케이션 연구에 유용한 시사점을 제안하고 있다.

• 한국공간구조학회논문집
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• 제19권3호
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• pp.41-50
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• 2019

The stone pagoda continued to be damaged by weathering and corrosion over time, and natural disasters such as earthquake are accelerating the destruction of cultural properties. Stone pagoda has discontinuous structure behavior and is very vulnerable to the seismic load acting in lateral direction. It is necessary to analyze various design variables as the contact surface characteristics play an important role in the dynamic behavior of stone pagodas. For this purpose, contact surface characteristics of stone pagoda can be classified according to surface roughness and filler type, and representative model is selected and structural modeling and analysis are performed using the discrete element method. Also, the seismic load according to the repetition period is calculated and the dynamic analysis is performed considering the discontinuous characteristics of the stone pagoda. Finally, the seismic behavior characteristics can be analyzed by the evaluation of stresses, displacements and structural safety.

• 한국가스학회지
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• 제4권1호
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• pp.33-39
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• 2000

긴 표면균열을 갖는 알루미늄합금(A5083)의 평판을 사용하여, 균열관통후의 응력확대계수를 검토하였다. 짧은 표면균열의 관통후에 제안된 식에 의하여 긴 표면균열 관통시의 평가는 균열종횡비가 적을수록 오차가 크게 되므로, 진전거동을 정확하게 평가하기 위해서는 수정이 필요하였다. 따라서 긴 표면균열 관통시의 종횡비를 고려하여, 응력확대계수의 평가식을 수정함으로써 관통후 고정도의 해석이 가능하였다.

• Journal of Ecology and Environment
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• 제29권1호
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• pp.49-53
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• 2006

The fiddler crab, Uca lactea, which lives on intertidal mudflats in Korea, exhibits both burrow mating and surface mating. We observed 17 cases of surface mating that occurred on Ganghwa Island, South Korea. Most surface-mating males did not build semidomes, structures that attract searching females for burrow mating. Based on the conclusion of a previous study that semidome building is condition-dependent, we suggest that food availability may influence the mating tactic of this species. In addition, there was a strong correlation between the carapace size of both sexes that surface-mated, which suggests that males use body size of females as a mating cue.

• 한국세라믹학회지
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• 제37권7호
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• pp.721-725
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• 2000

In this study, the dispersion stability of nano-sized CeO2 particles, synthesized by hydrothermal method in aqueous was evaluated from observing the surface potential behavior of CeO2 particle synthesized by solid state reaction. The isoelectric point(IEP) of nano-sized CeO2 synthesized by hydrothermal synthesis was found to be pH 9 contrary to the isoelectric point of micro-sized CeO2 synthesized by solid state reaction at pH 6.7. IEP was shifted to pH 2.0 as the addition of D-3019 from 0.1 to 1.0 wt%. The surface potential of CeO2 particles synthesized by hydrothermal synthesis was reduced as the addition of B-1001 used as a binder without change of IEP because the absorption of B-1001 polymer on the CeO2 particles shifted the shear plane of CeO2 particles outward away from the surface. This surface potential behavior was well correlated with the dispersion stability of slurry.

• 한국농공학회지
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• 제41권3호
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• pp.91-100
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• 1999

Tow constitutive models for weathered granite soil, Yasufuku's constitutive model with a single yield surface and Lade's constitutive model with two intersectiong yield surface compared in terms of their capabilities to accurately capture the observed behavior of compacted weathered grainite soil for various stress-paths. Both the single surface and the double surface models capture the experimentally observed behavior at a variety of stress-paths with good accuracy. The double surface model may model the observed compacted weathered granite soil behavior with better accuracy for proportational loading with increasing stress, but the single surface model may model dilatancy property with better accuracy for p-constant loading with increasing stress ratio.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.214-219
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• 2004

Crack tip behavior of single mode loading condition(mode I)depend on tensile loading component but one of mixed mode loading condition(mode I+II) have influenced on shear loading component like the practical structure. Because crack closure is caused by shear loading component under mixed-mode loading a research on the behavior in the stage of crack initiation and propagation require to be evaluate about crack closure effect by fatigue crack surface friction. For that reasion we examined the behavior at the crack tip by direct measuring method. Measured behavior at the crack tip was analyzed through vector crack tip displacement. As a result, crack propafation equation was corrected by considering with crack closure effect. In addition we compared fatigue fracture crack surface and crack closure level.

• 한국세라믹학회지
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• 제37권3호
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• pp.280-287
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• 2000

Adsorption behavior and amount of phenolic resin followed silica (SiO2) formation onto silicon nitride(Si3N4) surface were investigated using electrokinetic sonic amplitude (ESA) technique and with UV spectrometer, to fabricate Si3N4/SiC nano-composite based on reaction between SiO2 formed and phenolic resin absorbed onto Si3N4 particle. The amount of SiO2 formed and carbon from phenolic resin absorbed onto Si3N4 surface were calculated quantitatively to adjust the reaction between SiO2 and phenolic resin, resulting in no residual SiO2 and carbon. As a result, pre-heated tempeature for optimized reaction was below 25$0^{\circ}C$, in which there was no residual SiO2 and carbon.

• 한국해양공학회지
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• 제11권3호
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• pp.29-38
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• 1997

Crack penetration behavior by fatigue crack propagation and measurements of AE before-and-after crack penetration were examined using SS41 steel plate. Experimental crack shape of SU type was in good agreement with calculated shape rather than S type. Crack propagation behavior on the front surface appears not to change markedly after penetration. However, crack growth on the back surface appears to accelerate as reported by author. As a crack propagates, AE occurred heavily just before penetration. Then, it decreases and crack is penetrating. A transition from plane strain to plane stress was observed by fractographic study. At this time, separation of fracture surface was shown which affects AE occurrence.