• 한국지반공학회논문집
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• 제22권9호
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• pp.45-59
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• 2006

탄소성 구성방정식은 주로 미분방적식(rate equation)으로 이루어져 있기 때문에 유한요소법 등을 이용한 지반구조물 해석시 미분방정식들에 대한 수치적분을 수행할 수 있는 방법이 필요하다. 구조물의 거동을 해석할시 미분방정식들을 위한 적분방법은 해석결과의 정확성과 유한요소법 모델링의 안전성에 큰 영향을 미치고 있다. 본 논문에서는 최근에 개발되어 사용되고 있는 흙에 관한 구성모델인 "Two-surface soil plasticity model (Manzari and Dafalias 1997)"을 Implicit return-mapping 수치적분방법을 이용하여 실행하는 과정을 제시한다. 본 연구에서 사용된 수치적분방법은 Closest-Point-Projection Method(CPPM) 방법으로 탄성 예측자-소성 교정자(elastic predictor-plastic corrector) 개념을 Implicit Backward Euler방법으로 체계화 시킨 알고리듬이다. 본 연구에서 수행한 "Two-surface soil plasticity model"은 조립토의 비선형거동을 해석하며, Bounding surface 개념 및 비선형 등방경화와 이동경화법칙을 사용하는 모델이다. 본 연구는 CPPM 방법이 정확하고 안정되며 유용한 수치적분을 수행할 수 있는 알고리듬이라는 것을 제시한다. 또한, CPPM 알고리듬은 구성방정식의 해를 반복적으로 해석하는 동안 "Consistent tangent operator $d{\sigma}/d{\varepsilon}$"를 제공하므로, 비선형 유한요소 해석이 2차(quadratic convergence rate)의 수렴 조건을 만족하는데 기여한다는 것을 보여준다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권4호
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• pp.1216-1233
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• 2023

Conventional occupational therapy (OT) is conducted under the observation of an occupational therapist, and there are limitations in measuring and analyzing details such as degree of hand tremor and movement tendency, so this important information may be lost. It is therefore difficult to identify quantitative performance indicators, and the presence of observers during performance sometimes makes the subjects feel that they have to achieve good results. In this study, by using the Unity3D and artificial intelligence (AI) speaker, we propose a system that allows the subjects to steadily use it by themselves and helps the occupational therapist objectively evaluate through quantitative data. This system is based on the OT of the sensory integration approach. And the purpose of this system is to improve children's activities of daily living by providing various feedback to induce sensory integration, which allows them to develop the ability to effectively use their bodies. A dynamic OT cognitive assessment tool for children used in clinical practice was implemented in Unity3D to create an OT environment of virtual space. The Leap Motion Controller allows users to track and record hand motion data in real time. Occupational therapists can control the user's performance environment remotely by connecting Unity3D and AI speaker. The experiment with the conventional OT tool and the system we proposed was conducted. As a result, it was found that when the system was performed without an observer, users can perform spontaneously and several times feeling ease and active mind.

• 디지털융복합연구
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• 제12권9호
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• pp.201-207
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• 2014

클라우드 환경에서 기업은 의사결정이나 기업의 정책을 결정하기 위해 데이터 통합 및 분석이 필요하다. 그러나 이 환경에서 새로운 시스템이 추가되면 데이터 통합 측면에서 기존 시스템이 가진 이질적인 특성 때문에 많은 비용과 시간이 필요로 하게 된다. 따라서 본 논문에서 멀티 데이터베이스 서비스를 위하여 DBaaS 허브 시스템을 제안한다. 이러한 DBaaS는 서로 다른 데이터베이스를 요구할 수도 있으며, 연관성이 있는 서비스를 위하여 데이터를 통합해야할 필요가 있다. DBaaS의 데이터 상호운용성 문제를 해결하기 위해 온톨로지를 이용한 메타 쿼리를 제안한다. 메타 쿼리는 실제 데이터에 접근하기 위한 쿼리가 아닌 상위의 쿼리이다. 이는 실제 데이터베이스에 접근할 때 온톨로지를 통하여 변환된 질의로 접근함으로써 데이터 통합을 기할 수 있다. 또한 메타 데이터를 이용하여 문서 지향 데이터베이스 시스템을 구축한다.

• Architectural research
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• 제7권1호
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• pp.1-9
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• 2005

The needs of collaboration among design participants spread in different locations is emphasized in the early design stage in order to not only save time and provide places to meet and talk, but also to save cost for those events as well: This is being realized by the Internet, which helps support a networked, integrated real-time multi-user environment. As the base for collaboration activities moves from physical places to cyberspace, the methods of connecting every participant by means of a computer technology have been desired and considered. This study aims at investigating today's collaboration technology in the architectural design process, especially focused on the early stages, in terms of temporal dimensions. In addition, major concepts for and previous efforts and tools of collaborative design have been examined, and a specific recommendation has been proposed for future development of collaborative architectural design systems: That is distributed collaboration, which is accessible and comprehensible to all the professionals in the building design team, which not only allows the sharing of information but also the sharing of understanding, and which facilitates the development of design tools for different aspects of the envisioned collaborative design environment.

• Journal of information and communication convergence engineering
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• 제4권1호
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• pp.23-27
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• 2006

The discipline of software performance is very broad; it influences all aspects of the software development lifecycle, including architecture, design, deployment, integration, management, evolution and servicing. Thus, the complexity of software is an important aspect of development and maintenance activities. Much research has been dedicated to defining different software measures that capture what software complexity is. In most cases, the description of complexity is given to humans in forms of numbers. These quantitative measures reflect human-seen complexity with different levels of success. Software complexity growth has been recognized to be beyond human control. In this paper, we have focused our discussion on the increasing software complexity and the issue with the problems being faced in managing this complexity. This increasing complexity in turn affects the software productivity, which is declining with increase in its complexity.

• 디지털융복합연구
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• 제19권12호
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• pp.339-345
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• 2021

본 논문에서는 부가성 잡음이 존재하는 환경에서 진폭비교 모노펄스 레이더의 각도 추정 성능을 수치해석 기반으로 접근하여 분석한다. 편향 빔에 서로 상관이 없는 백색잡음이 추가되었을 때, 모노펄스 레이더의 각도 추정 성능을 평균제곱오차(MSE)를 통해 분석한다. 수치적분 기반의 평균제곱오차 결과는 몬테카를로 기반의 평균제곱오차 결과와 완벽히 겹치는 결과를 보이며 이는 몬테카를로 기반 평균제곱오차 결과에 99.8%에 해당한다. 또한 연산시간 측면에서 수치적분 기반의 평균제곱오차 분석법은 몬테카를로 기반의 평균제곱오차보다 매우 빠른 결과를 보인다. 따라서 제안된 수치적분 기반 평균제곱오차 방법을 통해 다양한 잡음환경에서 진폭비교 모노펄스레이더의 각도 추정 성능을 효율적으로 분석할 수 있다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.123-127
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• 2005

The numerical analyses of the complicated flows are widely attempted in these days. Because of the enormous demanding memory and calculation time, parallel processing is used for these problems. In order to obtain calculation efficiency, it is important to choose proper domain decomposition technique and numerical algorithm. In this research we enhanced the efficiency of the CFDS code developed by ADD, using parallel computation and newly developed numerical algorithms. For the huge amount of data transfer between blocks non-blocking method is used, and newly developed data transfer algorithm is used for non-aligned block interface. Recently developed RoeM scheme is adpoted as a spatial difference method, and AF-ADI and LU-SGS methods are used as a time integration method to enhance the convergence of the code. Analyses of the flows around the ONERA M6 wing and the high angle of attack missile configuration are performed to show the efficiency improvement.

• Bulletin of the Korean Chemical Society
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• 제10권6호
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• pp.529-535
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• 1989

A general perturbation series solution of the Smoluchowski equation is applied to investigate the rate of recombination and the remaining probability of a pair of particles in liquids. The radiative boundary condition is employed and the convergence of the perturbation series is analyzed in terms of a convergene factor in time domain. The upper bound to the error introduced by the n-th order perturbation scheme is also evaluated. The long time behaviors of the rate of recombination and the remaining probability are found to be expressed in closed forms if the perturbation series is convergent. A new and efficient method of purely numerical integration of the Smoluchowski equation is proposed and its results are compared with those obtained by the perturbation method. For the two cases where the interaction between the particles is given by (i) the Coulomb potential and (ii) the shielded Coulomb potential, the agreement between the two results is found to be excellent.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.42-47
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• 1999

In this study, we adopt the point symmetric Gauss-Seidel relaxation algorithm to obtain the steady state solution of the Navier-Stokes equations for the thermal and chemical nonequilibrium flow of air. All of the inviscid, viscous flux Jacobians and thermochemical source Jacobians are included in the implicit part Numerical simulation is performed for the thermal and chemical nonequilibrium flow over blunt body and computational results are presented. The convergence history and CPU time of the present computation are compared with the LU-SGS scheme which employs the approximate Jacobians.

• 한국전산유체공학회지
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• 제13권2호
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• pp.27-41
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• 2008

An unstructured hybrid mesh flow solver has been developed for the simulation of three-dimensional steady and unsteady incompressible flow fields. The incompressible Navier-Stokes equations with an artificial compressibility method were discretized by using a node-based finite-volume method. For the unsteady time-accurate computation, a dual-time stepping method was adopted to satisfy a divergence-free flow field at each physical time step. An implicit time integration method with local time stepping was implemented to accelerate the convergence in the pseudo-time sub-iteration procedure. The one-equation Spalart-Allmaras turbulence model has been adopted to solve high-Reynolds number flow fields. The flow solver was parallelized to minimize the CPU time and to overcome the computational overhead. This method has been applied to calculate steady and unsteady flow fields around submarine configurations and a 3-D infinite cylinder. Validations were made by comparing the predicted results with those of experiments or other numerical results. It was demonstrated that the present method is efficient and robust for the prediction of steady and unsteady incompressible flow fields.