• Journal of the KSME
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• v.25 no.6
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• pp.497-501
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• 1985

연속체역학은 고전역학을 종합하여 더 합리적인 체계로 정리 발전시키려는 금세기 후반에 집중된 노력의 결정으로 볼 수 있다(1,2). 연속체의 역학적 거동에 관한 기초적 개요를 쉽게 설명하고 관련문현을 제시하여 일반기술자의 관심을 돕고저 한다(연속체역학의 우리 용어들이 정립되지 않은 것은 필자 임의로 선택하였으니 양해를 바라며, 개요의 부족함은 기초적 문헌(4)으로 쉽게 보충되도록 유의하였다)

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.3
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• pp.137-145
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• 2014

We present a design sensitivity analysis(DSA) method for multiscale problems based on bridging scale decomposition. In this paper, we utilize a bridging scale method for the coupled system analysis. Since the analysis of full MD systems requires huge amount of computational costs, a coupled system of MD-level and continuum-level simulation is usually preferred. The information exchange between the MD and continuum levels is taken place at the MD-continuum boundary. In the bridging scale method, a generalized Langevin equation(GLE) is introduced for the reduced MD system and the GLE force using a time history kernel is applied at the boundary atoms in the MD system. Therefore, we can separately analyze the MD and continuum level simulations, which can accelerate the computing process. Once the simulation of coupled problems is successful, the need for the DSA is naturally arising for the optimization of macro-scale design, where the macro scale performance of the system is maximized considering the micro scale effects. The finite difference sensitivity is impractical for the gradient based optimization of large scale problems due to the restriction of computing costs but the analytical sensitivity for the coupled system is always accurate. In this study, we derive the analytical design sensitivity to verify the accuracy and applicability to the design optimization of the coupled system.

• Journal of the KSME
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• v.26 no.3
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• pp.214-218
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• 1986

제 4절에서 얻은 연속체 일반의 장방정식들을 제 5절에서와 같이 각종 물질의 구성방정식으로 보충하므로써, 탄성이론, Newton 유체역학, 비 Newton 유체역학, 소성이론, 점탄성이론, 비균질 체역학, 연속체 일반의 열역학 ...등의 기본적 이론체계를 구성할 수 있다. 또 합당한 경계조건과 함께 구체적 해를 얻는 다양한 연구로 이어진다. 이에 대한 독자의 편의를 위하여 몇 개의 문 헌을 뒤에 나열한다. (8,15,16,17,18,19) 공학의 한 분야에 전문적인 지식을 얻기 위해서는 공학 일반(engineering science)에 대한 선명한 이해가 필수적이며 이를 위해 연속체이론이 꾸준히 연구되고 있다. 그러나 이와 같은 방대한 체계를 $E_{3}$ 해석학의 틀 속에서 선명하게 파악 하려하는 것은 어려운 일이다. 결국 대역적해석학(global analysis)의 응용(3,5,20,21,22)이 불가 피하지 않나 생각된다. 이 방향의 연구가 선진국에서도 아직 소수의 학자들에 국한된 실정이나, 우리 공학의 획기적 발전을 위하여 독자들의 노력이 계속되었으면 한다.

• Journal of the Korean Geotechnical Society
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• v.36 no.12
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• pp.125-132
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• 2020

Embedded joints in the rock mass are a major constituent influencing its mechanical behavior. Numerical analysis requires a rigorous modeling methodology for the rock mass with detailed information regarding joint properties, orientation, spacing, and persistence. This paper provides a mechanical model for a jointed rock mass based on the implicit joint-continuum approach. Stiffness tensors for rock mass are evaluated for an assemblage of intact rock separated by sets of joint planes. It is a linear summation of compliance of each joint sets and intact rock in the serial stiffness system. In the application example, kinematic analysis for a planar failure of rock slope is comparable with empirical daylight envelope and its lateral limits. Since the developed implicit joint-continuity model is formulated on a continuum basis, it will be a major tool for the numerical simulations adopting published plenteous thermal-hydro-chemical experimental results.

• Bulletin of the Society of Naval Architects of Korea
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• v.29 no.3
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• pp.45-54
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• 1992

대략 17세기말-19세기초에 있었던 연속체 역학의 기본방정식이 이루어지는 과정을 살펴보고, 특히 재료역학의 발전이 이 과정에서 어떤 역할을 하였는지에 대해 조감하였다. 또한 이와 같은 역사가 우리 주변에 어떻게 투영되어 있는가를 살펴보고, 고체역학과 유체역학을 대비하여 앞으로의 발전 방향에 대해 생각해 보았다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.429-434
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• 2017

A molecular-continuum hybrid method was developed to simulate microscale and nanoscale fluids where continuum fluidics cannot be used to predict Couette flow. Molecular dynamics simulation is used near the solid surface where the flow cannot be predicted by continuum fluidics, and Navier-Stokes equations are used in the other regions. Numerical simulation of Couette flow was performed using the hybrid method to investigate the effect of solid-liquid interaction and surface roughness in a nanochannel. It was found that the solid-liquid interaction and surface roughness influence the boundary condition. When the surface energy is low, slippage occurs near the solid surface, and the magnitude of slippage decreases with increase in surface energy. When the surface energy is high, a locking boundary condition is formed. The roughness disturbs slippage near the solid surface and promotes the locking boundary condition.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2000.09a
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• pp.105-115
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• 2000

As large underground projects such as radioactive waste disposal, hot water and heat storage, and geothermal energy become influential, the study, which consider all aspects of thermics, hydraulics and mechanics would be needed. Thermo Hydro-Mechanical coupling analysis is one of the most complex numerical technique because it should be implemented with the combined three governing equations to analyze the behavior of rock mass. In this study, finite element code, which is based on Biot's consolidation theory, was developed to analyze the thermo-hydro-mechanical coupling in continuum rock mass. To verify the implemented program, one-dimensional consolidation model under the isothermal and non-isothermal conditions was analyzed and was compared with the analytic solution. The parametric study on two-dimensional consolidation was also performed and the effects of several factors such as poisson's ratio and hydraulic anisotropy on rock mass behavior were investigated. In the future, this program would be revised to be used for analysis of general discontinuous media with incorporating discrete joint model.

• Tunnel and Underground Space
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• v.10 no.3
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• pp.355-365
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• 2000

As large underground projects such as radioactive waste disposal, hot water and heat storage, and geothermal energy become influential, the study, which consider all aspects of thermics, hydraulics and mechanics would be needed. Thermo-Hydro-Mechanical coupling analysis is one of the most complex numerical technique because it should be implemented with the combined three governing equations to analyze the behavior of rock mass. In this study, finite element code, which is based on Biot's consolidation theory, was developed to analyze the thermo-hydro-mechanical coupling in continuum rock mass. To verify the implemented program, one-dimensional consolidation model under the isothermal and non-isothermal conditions was analyzed and was compared with the analytic solution. The parametric study on two-dimensional consolidation was also performed and the effects of several factors such as poisson's ratio and hydraulic anisotropy on rock mass behavior were investigated. In the future, this program would be revised to be used for analysis of general discontinuous media with incorporating discrete joint model.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.4 s.70
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• pp.453-458
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• 2005

This study deals with elasto-plasticity of granular micro-structures which recovers continuum elasto-plasticity in its counterpart. The theory is based on doublet mechanics that assumes particles of finite size and connecting linear springs, and it makes extensions to plasticity. The result shows that the micro model has one to one relationship with the continuum model in the simplest case. Micro-strain and micro-stress of two dimensional plane stress problem were calculated, which shows the behavior of the specimen and verifies the effectiveness of this model.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2000.11a
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• pp.3-3
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• 2000

저추진력 추력기라는 것은 추력이 수 N 정도, 노즐출구직경이 수 mm 정도의 소형추력기를 의미하며, 주로 인공위성을 비롯한 우주 비행체의 자세제어, 궤도천이 등의 목적을 위해 사용된다. 따라서, 저추진력 추력기의 일반적인 작동환경은 연속체 영역, 천이영역(transition flow regime), 희박영역(rarefied flow regime)을 모두 포함하므로, 기존의 연속체 유체역학에서 사용되는 Navier-Stokes 방정식을 사용할 수 없고, 분자들의 미시적인 움직임과 내부 에너지 분포를 고려한 Boltzmann 방정식을 이용한 해석을 수행하여야 한다.(중략)