• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.135-142
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• 2000

A framework alternative to that of classical slope stability analysis is developed, wherein the soil mass is treated as a continuum and in situ soil stresses and strengths are computed accurately using inelastic finite element methods with general constitutive models. Within this framework, two alternative methods of stability analysis are presented. In the first, the strength characteristics of the soil mass are held constant, and the gravitational loading on the slope system is increased until failure is initiated by well-defined mechanisms. In the second approach, the gravity loading on the slope system is held constant, while the strength parameters of the slope mass are gradually decreased until well-defined failure mechanisms developed. Details on the applying both of the proposed methods, and comparisons of their characteristics on a number of solved example problems are presented.

• Interaction and multiscale mechanics
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• 제1권2호
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• pp.279-301
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• 2008

This paper develops a 3D homogenization based continuum damage mechanics (HCDM) model for fiber reinforced composites undergoing micromechanical damage under monotonic and cyclic loading. Micromechanical damage in a representative volume element (RVE) of the material occurs by fiber-matrix interfacial debonding, which is incorporated in the model through a hysteretic bilinear cohesive zone model. The proposed model expresses a damage evolution surface in the strain space in the principal damage coordinate system or PDCS. PDCS enables the model to account for the effect of non-proportional load history. The loading/unloading criterion during cyclic loading is based on the scalar product of the strain increment and the normal to the damage surface in strain space. The material constitutive law involves a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. Three dimensional damage in composites is accounted for through functional forms of the fourth order damage tensor in terms of components of macroscopic strain and elastic stiffness tensors. The HCDM model parameters are calibrated from homogenization of micromechanical solutions of the RVE for a few representative strain histories. The proposed model is validated by comparing results of the HCDM model with pure micromechanical analysis results followed by homogenization. Finally, the potential of HCDM model as a design tool is demonstrated through macro-micro analysis of monotonic and cyclic damage progression in composite structures.

• 천문학회보
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• 제38권2호
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• pp.54-54
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• 2013

We performed spectroscopic and photometric monitoring observations of a QSO, PG0934+013 for a reverberation-mapping analysis, using the 9-m Southern African Large Telescope (SALT) for spectroscopy and the 2-m Faulkes Telescope North and the South for photometry. The monitoring campaign was carried out for 5 month between December 2012 to April 2013, providing 20 spectroscopic epochs and ~40 photometric epochs. Based on the obtained spectra, which typically have a signal-to-noise ratio to 30-60, we performed multicomponent decomposition using various components, i.e., power-law continuum, FeII emission complex, and broad and narrow emission lines, to properly measure the Hbeta line flux. After a flux normalization using [O III] 5007 line luminosity, we obtained a rms spectrum from all epochs, which shows clear variability of Hbeta line. We find that Hbeta line flux decreases by ~20% during the monitoring period while the continuum flux obtained from the aperture photometry based on the imaging data, shows similar variability. The current Hbeta light curve shows monotonic decrease and a reliable cross correlation analysis between Hbeta and continuum light is difficult. Nevertheless, we obtained a preliminary lag measurements as ~24 light days.

• Structural Engineering and Mechanics
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• 제70권4호
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• pp.445-455
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• 2019

Since the days of yore, plate's flexural analysis and formulation were dependent on the assumed coordinate system. In uncovering the coordinates-independent flexural interpretation, in this study, the plate bending analysis has been interpreted in terms of the tensor's components of curvatures and bending moments, in accordance with the continuum mechanics. The paper herein presents the theoretical formulations and conceptual perspectives of the Hydrostatic Method of Analysis (HM) that combines the continuum mechanics with the elasticity theory; the graphical statics and analysis; the theory of thin isotropic and orthotropic plates.

• 한국과학교육학회지
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• 제31권3호
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• pp.475-489
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• 2011

The purposes of this study were to inform the exemplary models of integrated science and mathematics and to analyze and discuss their similarities and differences of the models. There were two steps to select the exemplary models of integrated science and mathematics. First, the second volume (Berlin & Lee, 2003) of the bibliography of integrated science and mathematics was analyzed to identify the models. As a second step, we selected the models that are dealt with in the School Science Mathematics journal and were cited more than three times. The findings showed that the following four exemplary theoretical models were identified and published in the SSM journal: the Berlin-White Integrated Science and Mathematics (BWISM) Model, the Mathematics/Science Continuum Model, the Continuum Model of Integration, and the Five Types of Science and Mathematics Integration. The Berlin-White Integrated Science and Mathematics (BWISM) Model focused an interpretive or framework theory for integrated science and mathematics teaching and learning. BWISM focused on a conceptual base and a common language for integrated science and mathematics teaching and learning. The Mathematics/Science Continuum Model provided five categories and ways to clarify the extent of overlap or coordination between science and mathematics during instructional practice. The Continuum Model of Integration included five categories and clarified the nature of the relationship between the mathematics and science being taught and the curricular goals for the disciplines. These five types of science and mathematics integrations described the method, type, and instructional implications of five different approaches to integration. The five categories focused on clarifying various forms of integrated science and mathematics education. Several differences and similarities among the models were identified on the basis of the analysis of the content and characteristics of the models. Theoretically, there is strong support for the integration of science and mathematics education as a way to enhance science and mathematics learning experiences. It is expected that these instructional models for integration of science and mathematics could be used to develop and evaluate integration programs and to disseminate integration approaches to curriculum and instruction.

• 한국지반공학회논문집
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• 제36권12호
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• pp.125-132
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• 2020

암반내의 절리는 암반의 전체적인 역학적 거동에 중요한 역할을 한다. 암반에 대한 수치해석은 절리면의 역학적 물성, 방향성, 간격 그리고 연속성을 정교하게 모델링할수 있어야 한다. 본 논문의 내재적 절리-연속체 접근법은 절리군을 포함한 암반의 역학적 모델을 제시한다. 암반에 대한 강성 텐서는 온전한 암석과 절리군의 역학적 특성으로부터 산정하였다. 이는 온전한 암석과 절리군에 대한 연속적 강성 시스템의 컴플라이언스 텐서 합으로부터 산정할 수 있다. 암반사면의 평면파괴에 대한 수치해석은 기존의 daylight envelope과 측면한계를 적용하는 경험적인 방법과 상당히 일치함을 확인하였다. 개발된 내재적 절리-연속체 모델은 연속체 기반으로 수식화되어 기존의 절리에 대한 열-수리-화학적 실험적 결과들을 실제 수치해석에 적용할수 있을 것이다.

• 한국지반공학회논문집
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• 제22권7호
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• pp.5-12
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• 2006

본 연구는 사질토 지반에서의 얕은 터널굴착으로 인한 지반변형 거동을 규명하기 위해 연속체 사질토 지반을 모사 하는 알루미늄 봉과 근거리 사진계측기법을 이용하여 2차원 실내모형실험을 실시하였다. 실험결과에 근거하는 수치해석으로부터 생성된 변위벡터의 방향과 크기는 모형실험 결과와 거의 일치하였다. 특히, 벡터의 방향은 터널의 인버트 아래 어느 한 점을 향하는 것으로 나타났다. 좁은 "굴뚝 또는 튜울립" 형태의 수직변위는 수치해석 및 모형실험 결과에서 확인할 수 있었다. 이러한 양상은 현장에서 측정한 결과와 잘 일치된다. 정성적인 비교와 더불어 지중에서의 2차원 지반손실에 따른 정량적인 침하량 비교 결과, 모형실험에서 측정된 지중침하량이 수치해석 결과 잘 일치됨을 보여주었다. 따라서 본 모형실험에 적용된 근거리 사진계측기법은 수치해석 결과를 검증하는데 유용하게 사용될 수 있다.

• 한국방사선학회논문지
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• 제11권3호
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• pp.123-129
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• 2017

Compton suppression system은 스펙트럼에서 Compton continuum으로 존재하는 영역을 억제하는 장치 이다. 본 연구에서는 HPGe-NaI(TI)의 기하학적인 구조 파악 및 이동에 따른 이 때 그 효과를 최적화 할 수 있는 배치구조를 찾기 위하여, Monte Carlo simulation을 통해 Compton suppression의 행태적 특성을 파악하고, 몇 가지 배치구조에 대한 비교를 해보았다. 또한 거리에 따른 효율을 이용하여 환경 측정에 사용되는 실린더 비커에 적용해 보았다. ARF 값은 81.1 keV의 경우 약 1.65, 1332.4 에너지의 경우 약 1.9 정도로 나타내는 것을 확인할 수 있다. NaI(Tl) 검출기들의 위치 이동에 따라 특정한 영역에서 suppression이 일어나는 확인할 수 있다. Compton suppression system 구성의 목적에 비추어 볼 때, 결과 에너지 스펙트럼의 Compton continuum 영역 전반에 걸쳐 suppression이 이루어지는 것이 더욱 적절한 배치구조가 됨을 알 수 있다. 따라서 최적화된 구조를 통해 다양한 환경시료 측정에 적용할 수 있음을 확인 하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2000년도 봄 학술발표회논문집
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• pp.215-221
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• 2000

A simple numerical modeling technique is proposed for the analysis of framed tube structures with multiple internal tubes. The structures are analysed using a continuum approach in which each tube is individually modelled by a tube beam that accounts for the flexural and shear deformations, as well as the shear lag effects. By simplifying assumptions regarding the form of strain distributions in external and internal tubes, the structural behaviours is reduced to the solution of a single second order linear differential equation. The numerical analysis uses the variational approach on the basis of the minimum potential energy priniciple. Three framed-tube sructures with single, two and three internal tubes are analysed to verify the applicability and reliability of the proposed method.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
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• pp.20-27
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• 2005

I consider the structure of steady wave system which is admitted by the continuum equations for materials that undergo phase transformations with exothermic chemical reaction. In particular, the dynamic phase front structures between liquid and gas phases, and solid and liquid phases are computationally investigated. Based on the one-dimensional continuum shock structure analysis, the present approach can estimate the nano-width of waves that are present in combustion. For illustration purpose, n-heptane is used in the evaporation and condensation analysis and HMX is used in the melting and freezing analysis of energetic materials of interest. On-going effort includes extension of this idea to include broad range of liquid and solid fuels, such as rocket propellants.