• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.223-233
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• 2011

A design optimization problem was formulated to minimize the volume of an RC building structure while satisfying design constraints on structural displacements under vertical, wind and seismic loads. We employed metamodel-based design optimization using design of experiments, metamodeling and optimization algorithm to circumvent the difficulty of the automation of structural analysis procedure. Especially, we proposed a design approach of repetitive design optimizations by stages with changing the side constraint values on design variables and limit values on design constraints until a satisfactory design result was obtained. Using the proposed design approach, the volume of the RC building structure has been reduced by 53.3 % compared to the initial one while satisfying all the design constraints. This design result clearly shows the validity of the proposed design approach.

• Explosives and Blasting
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• v.37 no.2
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• pp.14-21
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• 2019

Distinct element method is a powerful numerical tool for modelling the jointed rock masses. It is also a useful tool for modelling of later stage of blasting requiring large displacement. The distinct element method utilizes a rigid block idea in which the interacting force between distinct elements is calculated from contact displacement as elements penetrate slightly. The properties of joints defined as the boundaries of distinct elements are critical parameters to determine the block behavior, and affect the deformation and failure mode. However, regardless of real joint properties, joint stiffnesses have sometimes been selected without special concern just to prevent elements from penetrating too far into each other in some quasi-static problems. Depending on whether the main interest in the analysis is the prediction of the deformation with high precision, or the prediction of the block behaviour after failure, the input data such as joint stiffness may or may not have a significant effect on the results. The purpose of this study is to provide a sound understanding of the effect of the joint stiffness on the distinct element analysis results, and to help guide the selection of input data.

• Journal of Korea Foundry Society
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• v.22 no.6
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• pp.299-303
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• 2002

수정된 SIMPLE법과 VOF의 결합으로 predictor-two step corrector-VOF라고 불리는 새로운 알고리즘이 주조 시 용탕 충전과정을 해석하기 위해 개발되었다. 운동량보존으로부터 유도된 새 2단계 속도 경계조건 처리법은 용탕의 자유표면을 추적하는 데 사용되었다. 본 연구에서는 2개의 예제 계산을 통해 계산정확도와 속도에 대한 Courant 수의 영향을 살펴보았다. 그 결과 적당한 Courant 수의 증가는 계산 정확도의 감소 없이 용탕 계산 속도를 향상시킬 수 있는 것으로 나타났다. 또한 만족할 만한 계산 정확도와 효율이 이 알고리즘의 실제 제품 해석을 통해 얻어졌다.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.269-274
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• 1996

월성원자력발전소 2호기와 같은 CANDU 6형 원자로의 반응도제어기구 설치대에는 여러 반응도제어기구가 삽입되기때문에 원자로심으로부터의 방사선흐름현상으로 인한 방사선피폭이 예상될 수 있는 위치이다. 좁고 긴 반응도제어기구 도관에서의 방사선 흐름으로 인한 반응도제어기구 설치대에서의 방사선량을 예측하기 위해 몬테 칼로 MCNP 코드를 1차원 각분할법 코드인 ANISN과 연계하여 사용하였다. 월성원자력2호기의 상단차폐해석을 위한 ANISN 계산, 도관의 방사선흐름을 평가하기 위한 MCNP 계산, 그리고 반응도제어기구 설치대에서의 방사선량율 평가를 위한 MCNP 계산등 3단계 계산 기법의 적응이 시도되었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.34-48
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• 2004

In this paper an optimization algorithm is suggested to reduce the huge computation time in the optimum design of large structures, especially in spacecraft structures. It combines the coupled load analysis model using a constrained mode of component mode synthesis and the modal transient analysis. The computer simulation code is developed and evaluated in optimizing spacecraft platforms. The developed algorithm can alleviate the computational load with adequate accuracy. From the optimization of a spacecraft structural member, the characteristics of each structural member can be understood.

• Computational Structural Engineering
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• v.7 no.2
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• pp.139-146
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• 1994

In this study, the finite element analysis using joint elements, bolt elements, and shell elements is presented to investigate the behavior of bolted connections. The contact of plates and the high-strength, pretensioned bolts are simply idealized by joint elements and bolt elements, respectively. The initial stiffness is determined through the presented method and the non-linear analysis is archived by a constant-arc-length method based on Newton-Raphson method. The analysis results of a semi-rigid connection(web & flange angles) and a moment connection (shear & moment plates) demonstrate the exactness and applicability of the presented method. And the results indicates that the consideration of slip and 3-dimensional deformation is needed for an accurate prediction of bolted connections.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.351-363
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• 2015

Discourse analysis is useful for examining discourse characteristics of dementia patients and differentiating them from normal adults. However, inconsistent tasks, transcription methods and measures have been utilized, thus analyses were inevitably unsystematic. The purpose of this study was to investigate tasks, transcription methods and measures of discourse studies in dementia. Studies on dementia discourses written in English were collected via Scopus database containing abstracts and citations from 2005 to 2014, and were analyzed in detail. From the results, the most frequently used task was 'storytelling-topic'. It was observed that use of consistent transcription conventions rendered more reliable transcription data. Measures could be categorized into coherence, cohesion, productivity, propositional syntactic lexical analysis, and fluency, and each category belonged to discourse processing levels (i.e., processing of conceptual networks, propositions, and natural language units). In conclusion, future research warrants not only utilization of discourse tasks depending on dementia types and features, but also application of consistent transcription conventions. Additionally, measures based on the discourse processing theory would enable us to systematically interpret discourse studies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.6 no.1
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• pp.53-60
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• 1996

오증 요소로부터 오류위치다항식의 계수를 계산함으로서 (23,12) Golay 부호를 복호할 수 있는 대수적 복호법이 최근 증명되었다. GF(2)상에서의 3중 오류정정 BCH부호의 복호법을 이 부호에 완벽하게 적용하여 해석하는 것을 소개한다. 그리고 GF(2)에 대한 최적의 정규기저를 구하여 이를 유한체 연산에 적용하며 단계별로 복호 회로의 구성을 제시한다. 이는 기존의 복호기보다 논리회로적으로 간단하며, 복호된 정보를 얻기까지 35번의 치환이 필요하다.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.885-888
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• 2009

자동차용 Alloy Wheel은 차량의 수직하중이나 가로 방향 하중, 구동, 제동토크 등 주행 시에 발생하는 여러 형태의 응력을 받으면서 사용되므로 이러한 응력을 견딜 수 있는 강성은 물론 차량 부품으로서의 요구 수명도 만족하여야 한다. 알루미늄 휠은 개발 후 규격에 준하는 내구성 평가를 위하여 반경 방향 부하 내구시험과 굽힘모멘트 내구시험과 주행 중 요철이나 벽돌 등에 의한 노면으로부터 갑작스런 하중에 대한 내충격성 평가를 위한 충격시험이 실행되고 있다. 이러한 시험은 많은 시간이 소요되고 있으며, 또한 시험 중 불합격 판정이 날 경우 또다시 처음의 공정을 모두 거쳐 다시 시험을 하게 된다. 3 Piece와 같은 알루미늄 휠은 여러 공정에 의한 생산되어지기 때문에 많은 시간적, 물질적 손실이 일어나고 있다. 따라서 자동차용 알루미늄 휠의 요구조건을 충분히 만족시키며 소비자의 요구에 맞는 품질과 시간을 충족시켜 기업경쟁력 확보는 물론 원가절감에 의한 기업 경쟁력 향상을 위하여 설계 단계서부터 시험조건을 고려한 내구성 해석에 의한 알루미늄 휠의 시험횟수를 단축하고자 한다. 본 논문에서는 3 Piece 알루미늄 휠의 축(shaft)하중에 의한 내구성 평가에 대하여 CAE시스템을 이용하여 보다 빠르고 정확한 결과를 산출함으로서 설계시간의 단축은 물론 다양한 형상의 제품들을 설계단계에서부터 생산에 이르기까지의 해석활용법을 수립하고자 하였다.

• Geotechnical Engineering
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• v.14 no.4
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• pp.129-140
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• 1998

Elasto-plastic finite element analysis of geotechnical boundary value problems necessitate the stress integration for the known strain increments. For the elasto-plastic constitutive model, the stress integration is generally achieved by numerical schemes, because analytical integration is impossible for general strain path. In this case, the accuracy of numerical stress integration has an important role on the overall accuracy of nonlinear finite element solution. In this study, the Sloan's substepping method which is one of explicit integration methods has been adopted and iris applicability has been checked. The unstability and inaccuracy of ifs results initiated from initial stress level were revealed. So. a new modified numerical integration method which employs the basic concept of modified Euler scheme for error control is proposed and accuracy and stability of the solutions are confirmed by triaxial test simulation.