• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.4
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• pp.293-300
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• 2012

In this study, the delamination analysis has been implemented to investigate the initiation and propagation of crack in composite laminates composed of orthotropic materials. A simple modeling was achieved by moving nodal technique without re-meshing work when crack propagation occurred. This paper aims at achieving two specific objectives. The first is to suggest a very simple modeling scheme compared with those applied to conventional h-FEM based models. To verify the performance of the proposed model, analysis of double cantilever beams with composite materials was implemented and then the results were compared with reference values in literatures. The second one is to investigate the behavior of interior delamination problems using the proposed model. To complete these objectives, the full-discrete-layer model based on Lobatto shape functions was considered and energy release rates were calculated using three-dimensional VCCT(virtual crack closure technique) based on linear elastic fracture mechanics.

• Journal of the Korean Magnetics Society
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• v.20 no.4
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• pp.149-152
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• 2010

The flat coil actuator is widely used to make high precision products because it has no friction between the moving coil and the guide. Finite Element Method, a favored actuator design tool due to its high accuracy, was utilized to analyze the electromagnetic actuator, but it consumes a lot of time especially in computation iterations for optimization. Accordingly, the magnetic equivalent circuit analysis can be an alternative tool to FEM because of its computation iteration capability with fair accuracy. In this paper, lumped parameter model and the simulation results are presented. In addition, the result of lumped parameter analysis is compared with those obtained from finite element analysis for verification.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.221-226
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• 2000

In this study, the characteristics of gas-water relative permeability curves in a single fractured-plate according to the various aperture size were analyzed by using the Hele-Shaw type glass plate model. The plate was made of glasses for the observation of the two-phase flow pattern, and seven cases were set up based on the aperture size in the range of field scale from 30 to $120\mum$. The experiment was conducted by steady-state method, and the water saturation was determined more accurately by the developed digital image process technique. The empirical equations of relative permeability to gas and water for single fractured-plate were correlated by using the aperture size which directly affects the two-phase flow pattern and critical saturation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.41-46
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• 2008

This paper conducts the research on the variation in the characteristics of the resonance and impedance of the metallic parallel plates due to the replacement of the normal dielectric substrate by the metamaterial. The ENG(${\epsilon}<0$), MNG(${\mu}<0}$) and DNG(${\epsilon},{\mu}<0$) types of metamaterial as well as the DPS(Double Positive) material are taken into consideration a full-wave modal analysis method known for accurate computation, as the SRR-kind of Lorentz model for permittivity and metal wire-periodic array-kind of Drude model for permeability, and the behaviors of parallel plates' resonance mode and impedance are observed. Based upon the observation, the design guidelines for the substrate can be addressed regrading how to suppress the parallel plates' spurious resonance modes that degrade the quality of the electronic equipment.

• Composites Research
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• v.18 no.4
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• pp.44-51
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• 2005

In this paper, we developed the direct numerical simulation(DNS) model considering the geometry of yams which consist of 3D orthogonal woven composite materials, and using this model, the dynamic behavior of under transverse low-velocity impact has been studied. To build up the micromechanical model considering tow spacing and waviness, an accurate unit structure is presented and used in building structural plate model based on DNS. For comparison, DNS results are compared with those of the micromechanical approach which is based on the global equivalent material properties obtained by DNS static numerical tests. The effects with yarn geometrical irregularities which are difficult to consider in a macroscopic approach are also investigated by the DNS model. Finally, the multiscale model based on the DNS concepts is developed to enhance efficiency of analysis with real sized numerical specimen and macro/micro characteristics are presented.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.6
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• pp.134-141
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• 2018

In this paper, the possibility of using an MDF (Mild-detonating Fuse) as a linear separation device is studied. An MDF is a small diameter metal (lead) tube filled with explosives (RDX). Aluminum plate cutting experiments are carried out with different values of target plate thickness and explosives per unit length. Based on the experimental results, a numerical analysis method including the failure criteria is established. The mechanism and characteristics of using MDFs for aluminum plate cutting are identified; the possibility of using the current system as a linear separation device is verified. By utilizing a developed numerical method, the separation reliability for diverse structures and MDFs can be predicted in advance and the number of experiments required for development can be minimized.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.319-322
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• 2006

Rapid mixing of air-fuel (<1 ms) is needed to accomplish supersonic combustion. In this experiment, helium was injected laterally in to the Mach 1.92 air flow. 2 kinds of model, flat plate/cavity, were used in this experiment and images were taken by schlieren visualization. Pressure was affected by shock structure in the supersonic duct, and penetration height was increased by increasing J. Penetration height was higher in the cavity model than flat plate model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.1
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• pp.1-14
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• 1999

선형탄성이론을 기초로 한 구조해석의 경우 사용하중상태에서의 변형과 응력은 만족할 만한 결과를 나타내지만, 항복후의 처짐과 파괴시의 극한하중 산정의 정확한 해석이 불가능하다. 평판의 극한해석시, 상한계 이론을 바탕으로 한 항복선 이론이 널리 사용되고 있으나 이론적으로 평판의 강도를 과대평가하게 된다. 그러므로, 임의의 하중조건과 경계조건에 대한 비선형 거동과 극한내하력을 산정할 수 있는 해석기법이 필요하다. 평판의 정확한 극한하중을 위해 p-Version 유한요소법을 제안하며, p-Version의 해석치를 범용 구조해석 프로그램인 ADINA의 결과와 문헌의 이론치와 비교하였다.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.749-758
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• 2000

This study presents a governing equations of bending behavior of sandwich plates with thick metal, polymer composite facings. Based on zig-zag models for through thickness deformations, the transverse shear deformation of composite facings is included. All edges of plate are assumed to be simply supported. Results of the bending analysis under lateral loads are presented for the influence of various lay up sequences of antisymmetric angle-ply laminated facings. The accuracy of the approach is ascertained by comparing solutions from the sandwich plates theory with composite facings to the laminated plates theory. Since the present analysis considers the bending stiffness of the core and also the transverse shear deformations of the laminated facings, the proposed method showed higher than that calculated according to the general laminated plates theory. The information presented might be useful to design sandwich plates structure with metal, polymer matrix composite facings.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.848-849
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• 2014

실시간으로 고객의 피드백을 파악할 수 있는 방법으로 SNS 등과 같은 빅 데이터를 이용하는 것이 매우 효율적 이다. 따라서 최근 기업들은 온라인상의 빅 데이터 평판을 분석하는 시스템들을 이용하여 고객피드백에 관한 정보를 수집하고 분석하고 있다. 본 논문에서는 온라인상의 고객피드백의 보다 정확하고 효율적인 정보 수집과 분석이 가능하며 분석 지식체계의 근간을 이루는 서비스 모델구축 방법을 제안한다. 서비스 모델 구축방법은 서비스 산업군에 대한 시소러스 분석 체계를 정의하고 데스트베드 대상의 인터뷰 등을 통하여 분류체계 기본 방향을 수립하며 타겟 대상의 특화된 수집원 및 범위를 설정하는 방법 등으로 이루어진다.