• Computational Structural Engineering
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• v.6 no.4
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• pp.83-88
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• 1993

A time-discontinuous Galerkin method based upon using a finite element formulation in time has evolved. This method, working from the differential equation viewpoint, is different from those which have been generally used. They admit discontinuities with respect to the time variable at each time step. In particular, the elements can be chosen arbitrarily at each time step with no connection with the elements corresponding to the previous step. Interpolation functions and weighting functions are taken to be discontinuous across inter-element boundaries. These methods lead to a unconditional stable higher-order accurate ordinary differential equation solver.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.1
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• pp.17-20
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• 2004

We derive specific heat gap at the critical temperature as an exact anylitical function of applied magnetic field by using the thermodynamics. And we calculate numerical value of specific heat gap for some superconductors with the derived results and discuss the physical meaning. And it will be discussed that gap of specific heat discontinuity under certain magnetic field intensity become zero at the critical temperature.

• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.112-114
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• 2004

마이크로스트림 회로는 제작하기 쉽고 능동 및 수동 소자를 편리하게 집적할 수 있기 때문에 많은 형태의 초고주파 회로와 그의 부 시스템은 마이크로스트립의 형태로 만든다. 그러나 마이크로스트림 회로의 문제점중의 하나인 휘어진 부분과 폭에서의 계단형 변화, 그리고 접합 점에서의 피할 수 없는 불연속점이 회로의 성능을 감쇄시킨다는 것을 확인하였다. 본 논문에서는 불연속점에서의 효과를 최소화시키기 위한 방법으로 집중소자를 회로에 포함시키는 방법과 모서리를 없애는 방법의 실험을 통하여 불연속성 효과를 최소화하는 됨을 확인하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.26 no.10
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• pp.1264-1274
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• 1999

본 논문에서는 분산된 클록들을 주기적으로 동기화 시키는 분산 실시간 시스템에서 시간적 제약을 만족시키기 위한 정적/동적 시간 제약(timing constraint) 변환 기법을 제안한다. 전형적인 이산클록동기화(discrete clock synchronization) 알고리즘은 클록의 값을 순간적으로 조정하여 클록의 시간이 불연속적으로 진행한다. 이러한 시간상의 불연속성은 시간적 이벤트를 잃어버리거나 다시 발생시키는 오류를 범하게 한다.클록 시간의 불연속성을 피하기 위해 일반적으로 연속클록동기화(continuous clock synchronization) 기법이 제안되고 있지만 소프트웨어적으로 구현되면 많은 오버헤드를 유발시키는 문제점이 있다. 본 논문에서는 시간적 제약을 동적으로 변환시키는 DCT (Dynamic Constraint Transformation) 기법을 제안하였으며, 이를 통해 기존의 이산클록동기화 알고리즘을 수정하지 않고서도 클록 시간의 불연속성에 의한 문제점들을 해결할 수 있도록 하였다. 아울러 DCT에 의해 이산클록동기화 하에서 생성된 태스크 스케쥴이 연속클록동기화에 의해 생성된 스케쥴과 동일함을 증명하여 DCT의 동작이 이론적으로 정확함을 증명하였다.또한 분산 실시간 시스템에서 지역 클록(local clock)이 기준 클록과 완벽하게 일치하지 않아서 발생하는 스케쥴링상의 문제점을 다루었다. 이를 위해 먼저 두 가지의 스케쥴링 가능성, 지역적 스케쥴링 가능성(local schedulability)과 전역적 스케쥴링 가능성(global schedulability)을 정의하고, 이를 위해 시간적 제약을 정적으로 변환시키는 SCT (Static Constraint Transformation) 기법을 제안하였다. SCT를 통해 지역적으로 스케쥴링 가능한 태스크는 전역적으로 스케쥴링이 가능하므로, 단지 지역적 스케쥴링 가능성만을 검사하면 스케쥴링 문제를 해결할 수 있도록 하였고 이를 수학적으로 증명하였다.Abstract In this paper, we present static and dynamic constraint transformation techniques for ensuring timing requirements in a distributed real-time system possessing periodically synchronized distributed local clocks. Traditional discrete clock synchronization algorithms that adjust local clocks instantaneously yield time discontinuities. Such time discontinuities lead to the loss or the gain of events, thus raising serious run-time faults.While continuous clock synchronization is generally suggested to avoid the time discontinuity problem, it incurs too much run-time overhead to be implemented in software. We propose a dynamic constraint transformation (DCT) technique which can solve the problem without modifying discrete clock synchronization algorithms. We formally prove the correctness of the DCT by showing that the DCT with discrete clock synchronization generates the same task schedule as the continuous clock synchronization.We also investigate schedulability problems that arise when imperfect local clocks are used in distributed real-time systems. We first define two notions of schedulability, global schedulability and local schedulability, and then present a static constraint transformation (SCT) technique. The SCT ensures that it is sufficient to check the schedulability of a task locally in a node with a local clock, since the global schedulability of the task is derived from its local schedulability through SCT. We formally prove the correctness of SCT.

• Tunnel and Underground Space
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• v.16 no.5 s.64
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• pp.394-404
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• 2006

Dynamic behavior of rock structures depends largely on the dynamic characteristics of ground and input earthquake wave. For blocky rocks with intense discontinuities, the mechanical characteristics of blocks and structural and mechanical characteristics of discontinuities affect overall behavior. In this study, UDEC was adopted to evaluate the dynamic behavior of rocks with various structural characteristics. Obtained results were compared to those of $FLAC^{2D}$, a continuum analysis, and the validity of the method was examined for dynamic analysis of discontinuous rocks for earthquake. Analysis considering the discontinuity showed significant changes in structural shape by the influence of joint behavior, and the behavior by continuum analysis was overestimated.

• Computational Structural Engineering
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• v.10 no.4
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• pp.143-154
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• 1997

Astochastic finite element model which reflects both the effect of discontinuities and the uncertainty of material properties in underground rock mass has been developed. Latin Hypercube Sampling technique has been mobilized and compared with the Monte Carlo simulation method. To consider the effect of discontinuities, the joint finite element model, which is known to be suitable to explain faults, cleavage, things of that nature, has been used in this study. To reflect the uncertainty of material properties, multi-random variables are assumed as the joint normal stiffness and the joint shear stiffness, which could be simulated in terms of normal distribution. The developed computer program in this study has been verified by practical example and has been applied to analyze the circular cavern with discontinuous rock mass.

• The Journal of Engineering Geology
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• v.7 no.2
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• pp.91-99
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• 1997

In general, there are various approaches available in literature to model discontinuous rock masses and engineers are often confused which one to use for designing structures in rock masses. Modelling rock masses can be classified mainly into two approaches. One is discrete modelling of intact rock and discontinuities and the other is the equivalent continuum modelling. In this study five models are selected ;(1) Crack tensor model, (2) Equivalent volume defect model, (3) Damage model, (4) Micro - structure model (Parallel model and Series model), and (5) Homogenization model. Most of these models are mainly concerned with how to define additional strain due to discontinuities over the representative elementary volume (REV) and how to relate the stress field of discontinuities to that acting on the REV. The characteristics of these models are clarified by comparing with results of some laboratory tests.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.267-275
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• 2022

Using a nonconforming mesh in enrichment methods results in several numerical issues induced by discontinuities and singularities found within the solution spaces, including the computational overhead during integration. In this study, we present a novel enrichment technique based on the selective expansion technique of moment fitting (Düster and Allix, 2020). In particular, two modifications are proposed to address the inefficiency during the integration process. First, a feedforward artificial neural network is introduced to correlate the implicit functions and integration moments. Through numerical examples, it is shown that the efficiency of the method is greatly improved when compared with existing expansion techniques, whereas the solution accuracy is maintained. Additionally, the finite element and domain representation grids are separated, which in turn improves the solution accuracy even for coarse mesh conditions.

• Korean Journal of Cognitive Science
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• v.27 no.3
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• pp.407-420
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• 2016

We live under the consequences of countless decisions, among which significant number of decisions is made by representatives acting on behalf of us. However, individuals often make disparate decisions depending on which identity they are assigned as an agent or with which opponent they are interplaying. In the current research, behavioral discontinuity depending upon actor identity and social relationship was investigated using the ultimatum game. Participants behaved in a more economically rational way when they acted as a group representative compared with when they made decisions as a private individual. However, the direction of the individual-representative discontinuity was reversed when rivalry came into play. Furthermore, more fairness was requested to accept the offers in the interaction with the rival compared with the neutral countergroup. Especially when interacting with the rival group, participants showed contrasting level of decision bias - measured by rejection rate toward unfair offers - according to the degree of mind attribution to the opponent. Specifically, the greater participants attributed a mind to the rival group, the more they rejected the unfair offers from it. The present research is important in that it provides insight into individuals' decision-making in a group context, which sometimes forgoes the financial gain of the entire group and ultimately leads to the sub-optimization of social welfare.

• The Journal of Engineering Geology
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• v.10 no.3
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• pp.273-275
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• 2000

Engineering Geology를 필자는 지질공학(地質工學)이라 한다. 지질공학은 지반(地盤)의 토질 및 암석의 거동을 역학적인 관점에서의 지질역학(地質力學, Mechanical Geology)과 공학적 판단을 가하여 실제의 공사 등에 응용되는 기초학문이다. 이 분야에서의 중요 부분은 토목 시공 과정 또는 시공후에 발생할수 있는 지질적 문제(지질약선대의 문제 및 지질역학적 문제)등 에 대한 조사연구인 것이다. 따라서 지질공학자는 암반의 기계적인 응답에 대한 요소들을 지질도에 표시하여 시공상의 문제점을 검토, 연구하여 착공여부를 결정하고 지반보강 또는 지질개선을 실시케한다. 문제 중 지반의 거동은 물질 자체의 성질과 불연속성면에 있다. 물질자체의 성질은 입자의 크기에 있고 구조적 집합성에 있는 것이다. 불연속성면은 미세한 균열에서 거대한 단층면에 이르기까지 존재하며, 구조지질역학적 성격에 있다. (중략)