• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.413-417
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• 2004

Recent experiments have shown the 'size effects' in micro/nano scale. But the classical plasticity theories can not predict these size dependent deformation behaviors because their constitutive models have no characteristic material length scale. The Mechanism - based Strain Gradient(MSG) plasticity is proposed to analyze the non-uniform deformation behavior in micro/nano scale. The MSG plasticity is a multi-scale analysis connecting macro-scale deformation of the Statistically Stored Dislocation(SSD) and Geometrically Necessary Dislocation(GND) to the meso-scale deformation using the strain gradient. In this research we present a study of nano-indentation by the MSG plasticity. Using W. D. Nix and H. Gao s model, the analytic solution(including depth dependence of hardness) is obtained for the nano indentation , and furthermore it validated by the experiments.

• 해양환경안전학회지
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• 제27권4호
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• pp.538-549
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• 2021

본 연구에서는 Froude 수 1.0으로 운항하는 길이 약 10m 급 소형 고속선박의 에너지 효율 설계를 위해 선미부에 트림 탭을 부착하였고, 선저 면과의 각도에 따른 항주자세와 저항성능의 변화를 살펴보았다. 성능 해석은 CFD 해석을 통해 수행되었으며, 축척에 의한 영향을 보기 위해 모형선과 실선에 대해 각각 해석을 수행 후 두 결과로부터 예측된 실선의 성능을 비교하였다. 나선에 대한 해석 결과는 두 결과가 전반적으로 유사하였고, 트림 탭이 부착된 경우 선저 면과의 각도가 동일할 때 자세 변화량이 달라 전 저항의 차이로 이어졌지만 자세에 따른 저항 변화 경향은 유사하였다. 이로부터 축척 효과가 있더라도 저항 저감 경향으로부터 최적 항주자세를 찾을 수 있으나, 트림 탭에 의한 자세 변화와 실선 주위 유동의 특성을 알기 위해서는 실선에 대한 직접적인 해석이 필요함을 알 수 있다.

• 한국의류학회지
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• 제19권6호
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• pp.984-994
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• 1995

The dimensional structure of impression formed of a female figure in specific attire was identified and significant influence of skirt length and suit color on impression formed of figures in suits were researched in the part I of this study. In part ll, the effect of identical elements of apparel design on impression formation of a female figure in dress and pants- blouse were studied. The experimental matirals consisted of two sets of stimuli and 7 point semantic differential response scale developed in part 1. Each set of stimuli was composed of 20 drawings representing female figures in each attire. Three independent variables, which were the length of bottom, color of dress or pants and collar type of blouse, were manipulated in each stimulus. The experiment was arranged by 3 factorial design, and the data were analyzed by 3-way ANOVA and by Multiple Classification Analysis. To summarize, in impression formation of figure in dress, the most dominant design element was identified as bottom length and the second most dominant one was color of dress. In contrast, in perception of figure in pants-blouse, the most important design element was color of pants and secondly important one was bottom length. The collar type of top didn't have critical effect on impression formation of figures in both type of attire.

• Child Health Nursing Research
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• 제8권2호
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• pp.204-216
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• 2002

The purpose of this study was to investigate the effect of massage therapy on weight gain, length and head circumference in instituted infants. This study utilized nonequivalent control group with repeated measuring by quasi experimental design. Fifty eight instituted infants in Daejeon city were selected for the study. Fifty eight infants were randomly assigned two groups, one served as the control group and the other was experimental group to whom massage therapy was given. For the experimental group, massage protocol(developed by Field, 1986) was applied 2 times a day, mid-morning and early evening, for 4 weeks for each infants by researcher and trained research assistants. As a weight weighing instrument, electronic indicator scale (Cas Co., Korea) was used. The result of this study were summarized as follows; 1.A repeated measures ANOVA identified a significant group by time effect over the four weeks of intervention(F=14.69, p < .0001). Infants assigned to experimental group gained more weight than control group infants. 2. T-test identified that significant differences in length(t=2.60, P=.013) and head circumference(t=4.27, P=.000). Infants assigned to experimental group had more length and head circumference than control group infants. In conclusion, Massage therapy improved weight gain, length and head circumference of instituted infants. Therefore, it is recommended to utilize massage therapy as a nursing intervention for instituted infants.

• 한국의류학회지
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• 제20권4호
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• pp.631-646
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• 1996

The purpose of this study was to investigate the difference of visual evaluation about silhouette image. The specific objective were; 1) to construct of silhouette image evaluation instrument using semantic differential scale for the purpose of measuring the width and length; 2) to identify the factor structure of the silhouette; 3) to test the difference of visual perception to the silhouette as the variation of width; 4) to test the difference of visual perception to the silhouette as the variation of length; 5) to test interaction effect between width and length. The major finding were; For the visual evaluation of silhouette as shoulder width variatiorl, there were significant difference in hardness and softness factor. For the hard and soft image, we should express by variation of the shoulder width. For the visual evaluation of silhouette as skirt width variation, there were significant difference in attention factor. For the attensive image, we should express by variation of the skirt width. For the visual evaluation of silhouette as skirt length variation, there were significant difference in activity factor. For the active image, we should express by variation of the skirt length.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.203-210
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• 2002

The past bridge design specifications of Korea didn't include 1imitation on the amount of lap splices in the plastic hinge zone of piers, and so do current specifications. But these specifications include just limitation on the minimal length of lap splices. Thus, a large majority of non-seismically designed bridge piers may have lap splices in plastic hinge zone. In this study, model pier was selected among existent bridge piers whose failure mode is complex shear-flexure mode. Full scaled RC pier models whose aspect ratio is about 2.67 were constructed and quasi static test according to the drift level history was implemented. From the test results, effect of the lap splices on the seismic performance of bridges piers was analyzed, and the seismic capacity of the model bridges was evaluated by capacity spectrum method.

• 대한기계학회논문집B
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• 제20권10호
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• pp.3282-3292
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• 1996

Flow velocity was measured using a hot wire anemometer. Turbulence intensity was in proportion to mean flow velocity regardless of swirl velocity. And integral length scale has proportional relation with swirl velocity regardless of measurement position. Flame speed calculated by radius of visualized flame was increased and then decreased according to lapse of time from spark. Maximum flame speed was increased according to increase of turbulence intensity. Burning speed and flame transport effect increased with increase of swirl velocity, but ratio of burning speed to flame speed decreased with increased of swirl velocity. Mass fraction burned versus volume fraction burned was increased in proportion to the increase of turbulence intensity, caused by increase of combustion promotion effect according to increase of turbulence intensity and scale.

• Structural Engineering and Mechanics
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• 제71권1호
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• pp.37-43
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• 2019

This paper studies application of modified couple stress theory and first order shear deformation theory to magneto-electro-mechanical vibration analysis of three-layered size-dependent curved beam. The curved beam is resting on Pasternak's foundation and is subjected to mechanical, magnetic and electrical loads. Size dependency is accounted by employing a small scale parameter based on modified couple stress theory. The magneto-electro-mechanical preloads are accounted in governing equations to obtain natural frequencies in terms of initial magneto-electro-mechanical loads. The analytical approach is applied to investigate the effect of some important parameters such as opening angle, initial electric and magnetic potentials, small scale parameter, and some geometric dimensionless parameters and direct and shear parameters of elastic foundation on the magneto-electro-elastic vibration responses.

• 소성∙가공
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• 제13권3호
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• pp.248-252
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• 2004

The mechanical properties of polycrystalline thin-films, critical for Micro-Electro-Mechanical Systems (MEMS) components, are known to have the size effect and the scatter in the length scale of microns by the numbers of intensive investigation by experiments and simulations. So, the consideration of the microstructure is essential to cover these length scale effects. The lattice based stochastic model for the microstructure evolution is used to simulate the actual microstructure, and the fast and reliable algorithm is described in this paper. The kinetics parameters, which are the key parameters for the microstructure evolution based on the nucleation and growth mechanism, are extracted from the given micrograph of a polycrystalline material by an inverse method. And the method is verified by the comparison of the quantitative measures, the number of grains and the grain size distribution, for the actual and simulated microstructures. Finite element mesh is then generated on this lattice based microstructure by the developed code. And the statistical finite element analysis is accomplished for selected microstructure.

• 천문학회보
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• 제36권1호
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• pp.85.2-85.2
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• 2011

We investigate the driven magnetohydrodynamic (MHD) turbulence by including the effect of the expansion and collapse of background medium. The main goal is to quantify the evolution and saturation of the strength and characteristic length scales of magnetic fields in expanding and collapsing media. Our findings are as follows. First, with the expansion and collapse of background medium, the time evolution of the magnetic and kinetic energy densities depends on the nature of forcing as well as the rate of expansion and collapse. Second, at scales close to the energy injection (or driving) scale, the slope of magnetic field power spectrum shallows with expansion but steepens with collapse. Third, various characteristic length scales, relative to the energy injection scale, decrease with expansion but increase with collapse. We discuss the astrophysical implications of our results.