• Membrane Journal
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• v.28 no.1
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• pp.37-44
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• 2018

Polysulfone composites including graphene were prepared, and their thermal characteristics in membrane states were analyzed by using a custome-made residual stress analyzer and a thermal diffusivity analyzer based on laser flash method. The residual stress analysis was carried out on the polysulfone composite films deposited on Si (100) substrates for 1 cycle of heating and cooling runs. The flat membrane of graphene-embedded polysulfone composites were prepared by the phase transfer method in distilled water and the thermal conductivity was separately measured in the out-of-plane and the in-plane directions. The residual stress of the graphene-embedded polysulfone film was gradually decreased with increasing graphene loading and the out-of-plane thermal conductivity was distinguished from the in-plane thermal conductivity in the flat membranes. These thermal characteristics are caused by the structural uniqueness of graphene and the micro-void structures formed during membrane fabrication.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4294-4301
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• 2012

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models and variable earthquakes are studied. Three earthquake records of El-centro, Santa-Monica, Taft in accordance with KBC2009 standard and four inelastic hysteresis models such as Degrading tri-linear model, Clough model, Takeda model, and Modified Takeda model are used. The inelastic response characteristics such as story shear force, story drift ratio, story displacement are reviewed. As results, El-centro earthquake shows large response in transverse direction and Santa Monica earthquake shows larger response in longitudinal direction on the contrary. Taft earthquake shows less variation of story drift ratio and story displacement for all hysteresis models and stable response.

• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.769-782
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• 2006

As the ambient vibration test (AVT) of railway bridges has a limited range of speed, it has a limitation in examining the dynamic behavior of bridges accordingto speed. Thus, in order to analyze the correlation between the speed of a train passing over a bridge and the bridge's dynamic response, we conducted a speed-increasing experiment using a real diesel locomotive. To analyze the acceleration response characteristics, we attached seven vertical accelerometers at equal intervals throughout the entire section of the bridge except the supports, and one horizontal accelerometer to the middle span. Linear variable differential transformers (LVDT) were installed at the bridge's center in both vertical and horizontal directions to investigate the vertical and horizontal behaviors. The test train was statically loaded at the center and at the end of the bridge. And its speed was increased from 5 km/h to 90 km/h. With data obtained from the experiment, the vibration level was evaluated in each direction by the filtering frequency, and the level of horizontal vibration was examined in comparison with vertical vibration. The displacement and wheel load variation was analyzed by speed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.10
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• pp.1269-1278
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• 2013

The cutting area changes periodically in the end-milling process because of its form generation mechanism. In this study, the effects of the cutting area on end-milled side walls are studied by developing a cutting area model that simulates the area formed by engagement between a workpiece and a cutting edge of the end mill. To do this, the straightness profile of the side wall in the axial direction is investigated. Models for estimating the cutting area and the transition point, where the slope of the straightness profile changes suddenly, are verified from real end-milling experiments under various radial and axial depth of cut conditions. Through this study, it is confirmed that the final end-milled side wall is generated in the regions where cutting areas are constant and decreasing in the down-cut. Similarly, in stable up-cut, it is also generated in the regions where cutting areas are increasing and constant. It is found that the transition point appears when the region changes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.2
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• pp.353-359
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• 2006

As for the characteristic of elements for a lot of communication used in light communication systems, it is affected according to structure of directional coupler. We carried out study on a characteristic of the directional coupler which had waveguide structure to have perturbation phenomenon in this paper and ran simulation on the characteristic that we changed structure of directional coupler too, and was got. Confirmation was able to do that it operated with an optical filter, and the directional coupler which added waveguide structure to produce perturbation phenomenon by the results was able to confirm what we adjusted duty ratio of waveguide structure too, and operated with a more excellent optical filter. Through simulation, the case that duty ratio changed than the case that duty ratio of waveguide structure was $50\%$ was able to get an excellent answer characteristic of a -l8dB degree.

• Tunnel and Underground Space
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• v.31 no.1
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• pp.66-81
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• 2021

The effects of directional fracture tensor components and first invariant of fracture tensor on deformation moduli and shear moduli of fractured rock masses is analyzed based on regression analysis performed between 3-D fracture tensor parameters and deformability of DFN blocks. Using one or two deterministic joint sets, a total of 224 3-D discrete fracture network (DFN) cube blocks were generated with various configurations of deterministic density and probabilistic size distribution. The fracture tensor parameters were calculated for each generated DFN systems. Also, deformability moduli with respect to three perpendicular direction of the DFN cube blocks were estimated based on distinct element method. The larger the first invariant of fracture tensor, the smaller the values for the deformability moduli of the DFN blocks. These deformability properties present an asymptotic pattern above the certain threshold. It is found that power-law function describes the relationship between the directional deformability moduli and the corresponding fracture tensor components estimated in same direction.

• Journal of Welding and Joining
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• v.15 no.5
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• pp.1-10
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• 1997

본 논문에서는 플라즈마 용사 코팅 기술에 대해 알아보기 위해서 고온의 열원인 플라즈마의 특성, 플라즈마 용사방법, 코팅 특성 및 응용에 대해 검토하고, 향후 연구방향에 대해 서술한다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.2
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• pp.153-160
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• 2015

The objective of this study is to construct the TPU aerodynamic database with wind tunnel test data of overall wind loads and responses on tall buildings. In this study, wind tunnel tests were conducted to investigate characteristics of wind forces and the effect of wind load combination by cross-correlation analysis among along-wind overturning moment, across-wind overturning moment and torsional moment on a tall building with various side ratios(D/B=0.33, 0.50, 0.77, 0.83, 0.91, 1.0, 1.1, 1.2, 1.3, 2.0 and 3.0) for different terrain roughnesses. The results of wind tunnel tests were compared with those of past literatures. As a result, there was no significant effects of changing of terrain roughnesses on moment coefficients and power spectral densities of across-wind overturning moment coefficients and torsional moment coefficients with various side ratios. Further, these results were good agreement with those of past literatures. From cross-correlation analysis, the across-wind overturning moment coefficients were highly correlated with the torsional moment coefficients. The results of this study will be helpful for practical designers in preliminary design stage.

• Journal of Global Scholars of Marketing Science
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• v.3
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• pp.63-77
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• 1999

지방자치단체별로 특성화된 이벤트의 개발은 지역사회의 경제 문화 발전에 많은 영향을 끼치면 또한 주민들의 적극적인 참여로 인해 그 시너지효과는 더욱 커진다. 지역이벤트를 개최목적과 지역특성반영정도에 따라 분류하였다. 이벤트개최목적을 주민공동체의식함양과 지역경제활성화로 나누고, 또한 이벤트의 내용이 지역특성을 반영하는 정도에 따라 분류하여 이벤트의 형태를 4가지로 나누었다. 지역주민공동체의식함양을 목적이며 지역단위특성이 있는 이벤트를 지역고유이벤트라 하였고, 이는 지역의 전통문화 또는 지역의 지리적특성 등을 살리면서 지역주민의 공동체의식을 높이는 것을 목적으로 하는 이벤트이다. 반면에 같은 목적을 가지면서도 지역특성이 반영되는 정도가 낮은 이벤트가 있을 수 있다. 이는 체육대회 등 순수 공동체의식제고에 목적을 둔 이벤트이다. 또한 문화적 요인 등 뿐만 아니라 지역산업의 특성을 지니면서 지역경제활성화를 목적으로 하는 이벤트가 있을 수 있고, 동일한 목적을 지향하지만 지역단위특성을 반영하는 정도가 낮은 이벤트가 있을 수 있다. 본 연구에서는 경남과 전남에서 실시되고 있는 이벤트들의 현황을 보고, 동서지역 특성을 살핀 다음, 동서지역 특성에 맞는 이벤트 개발방향을 모색하였다. 경남과 전남은 각기 독특한 특성을 가지면서도 수려한 한려해상, 지리산, 섬진강과 같은 자연자원을 공유하고 있으며, 또한 전남과 경남 공히 넓은 평야를 중심으로 하는 쌀농사라는 공통점이 있고, 그리고 전남에는 제철, 석유화학 등 기간산업이 경남지역에는 중공업 산업들이 발달해 있다. 이러한 요인들을 결합하여 양지역의 특성을 살리면서 효과적으로 연계할 수 있는 이벤트 개발방향이 모색되었다. 또한 충무공 이순신, 장보고, 사명대사, 허준과 같은 역사적 인물들이 동서지역을 넘자들면서 활동을 하였는 바 이를 이벤드화 하는 방안도 모색되었다.

• Fire Science and Engineering
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• v.18 no.4
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• pp.35-41
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• 2004

The water spray characteristics of the sprinkler heads is a very important factor affecting the fire suppression performance, and it is largely dependent on the shape of the head nozzle. This study investigated shape factors and spray distribution performances for the sprinkler heads of four domestic companies with big market shares. The experimental results revealed that all flow constants exceeded the required regulation limits, however showed big differences between head types although they have the same design limit. They were however relatively consistent regardless of the pressure increases. The spray distribution of some head samples showed severe directional eccentricity, which suggests more study for the improvement.