• Nuclear Engineering and Technology
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• 제46권4호
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• pp.481-488
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• 2014

An analysis of the uncertainty quantification related to LBLOCA using the Monte-Carlo calculation has been performed and compared with the tolerance level determined by the Wilks' formula. The uncertainty range and distribution of each input parameter associated with the LOCA phenomena were determined based on previous PIRT results and documentation during the BEMUSE project. Calulations were conducted on 3,500 cases within a 2-week CPU time on a 14-PC cluster system. The Monte-Carlo exercise shows that the 95% upper limit PCT value can be obtained well, with a 95% confidence level using the Wilks' formula, although we have to endure a 5% risk of PCT under-prediction. The results also show that the statistical fluctuation of the limit value using Wilks' first-order is as large as the uncertainty value itself. It is therefore desirable to increase the order of the Wilks' formula to be higher than the second-order to estimate the reliable safety margin of the design features. It is also shown that, with its ever increasing computational capability, the Monte-Carlo method is accessible for a nuclear power plant safety analysis within a realistic time frame.

• Structural Engineering and Mechanics
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• 제89권3호
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• pp.239-252
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• 2024

Steel plate shear walls (SPSWs) are classified as lateral load-resisting systems. The feasibility of openings in the steel plate is a characteristic of SPSWs. The use of openings in SPSWs can lower the load capacity, stiffness, and energy dissipation. This study proposes a novel form of SPSWs that provides convenient access through openings by combining steel plates and eccentrically braced frames (EBFs). The proposed system also avoids a substantial reduction in the strength and stiffness. Hence, various geometric forms were analyzed through two different structural approaches. Groups 1, 2, and 3 included a steel EBF with a steel plate between the column and EBF in order to improve system performance. In Group 4, the proposed system was evaluated within an SPSW with openings and an EBF on the opening edge. To evaluate the performance of the proposed systems, the nonlinear finite element method (NL-FEM) was employed under cyclic loading. The hysteresis (load-drift) curve, stress contour, stiffness, and damping were evaluated as the structural outputs. The numerical models indicated that local buckling within the middle plate-EBF connection prevented a diagonal tension field. Moreover, in group 4, the EBF and stiffeners on the opening edge enhanced the structural response by approximately 7.5% in comparison with the base SPSW system.

• 전자공학회논문지
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• 제50권11호
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• pp.99-107
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• 2013

Controller Area Network (CAN)의 개발 목적은 차량 내 Electronic Control Units (ECUs)간의 다중 통신을 통해 자동차에서 큰 부피와 무게를 차지하는 와이어 하네스를 저비용의 네트워크 케이블로 대체하기 위한 것이었다. 차량에 탑재되는 ECU들의 증가로 인해 CAN 데이터 전송량이 많아짐에 따라 CAN 버스로드와 오류 확률도 증가하고 있다. CAN 데이터 전송 시간은 CAN 프레임의 길이에 비례하기 때문에 프레임의 길이를 줄이게 되면 효율적으로 CAN 버스로드와 오류확률을 감소시킬 수 있다. 본 논문에서는 CAN 메시지 길이를 감소시키기 위해 Data Length Code(DLC)와 전송 데이터 압축영역 설정 절차를 사용한 CAN 메시지 압축 알고리즘을 제안한다. 제안한 방법에서는 기존의 알고리즘과 달리 변화량을 저장하기 위한 최대 변화량의 범위를 설정하지 않아도 되기 때문에 부정확한 설정에서 발생하는 오류나 지나친 설정에서 발생하는 압축효율 저하를 피할 수 있다. 또한, DLC 크기에 의해 압축 유무를 판단함으로써 기존 방법에서 제안된 두 개의 ID로 압축 여부를 판단하는 비효율적인 문제점을 해결할 수 있다. 실제차량 주행 후 얻은 데이터로 시뮬레이션 해본 결과, 기존의 방법에 비해 최대 52%까지 더 압축된 것을 확인하였다. 또한, 임베디드 테스트 보드를 이용하여 테스트 했을 때 한 개의 64비트 EMS CAN 데이터를 압축하는데 0.16ms가 소요되어 차량용 CAN 통신에 사용가능함을 보인다.

• 조명전기설비학회논문지
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• 제24권2호
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• pp.113-119
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• 2010

안전한 접지설계는 사고 시에 대지로 고장전류를 흘려보내는 수단과 인체가 사고기기에 접촉 시에 위험에 노출되지 않도록 하는데 있다. 변압기 중성점 접지는 1선 지락사고 시 중성점전위가 허용치 이하가 되도록 접지되어야 한다. 변압기 외함 접지는 절연사고로 외함에 전류가 흐를 때 인체 허용전압과 전류 이내로 저감시키는 목적으로 사용되고 있다. 본 논문에서는 사고 시 중성점 전위와 접촉전압을 계산하여 배전 변압기의 접지저항 영향을 심도있게 분석하였다.

• Structural Engineering and Mechanics
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• 제42권6호
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• pp.815-829
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• 2012

This paper proposes a nonlinear computational modeling approach for the behaviors of structural systems subjected to fire. The proposed modeling approach consists of fire dynamics analysis, nonlinear transient-heat transfer analysis for predicting thermal distributions, and thermomechanical analysis for structural behaviors. For concretes, transient heat formulations are written considering temperature dependent heat conduction and specific heat capacity and included within the thermomechanical analyses. Also, temperature dependent stress-strain behaviors including compression hardening and tension softening effects are implemented within the analyses. The proposed modeling technique for transient heat and thermomechanical analyses is first validated with experimental data of reinforced concrete (RC) beams subjected to high temperatures, and then applied to a bridge model. The bridge model is generated to simulate the fire incident occurred by a gas truck on April 29, 2007 in Oakland California, USA. From the simulation, not only temperature distributions and deformations of the bridge can be found, but critical locations and time frame where collapse occurs can be predicted. The analytical results from the simulation are qualitatively compared with the real incident and show good agreements.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.325-329
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• 2002

This study targets mainly to reduce the manufacturing costs of cam spindles and manufacturing of mechanical components with longer service durations through application of surface engineering techniques on cam spindles. Within the frame of this study, we have attempted to establish the performances of cam spindles manufacture from forged steel and SGCI, through performance of wear tests in plate-disk system, metalographic investigations, SEM imaging, EDS analyses and micro hardness scans on test samples having the same sizes with original cam that once obtained from casting of Spherical Graphite Cast Iron (SGCI) are subjected partially to Boronising and partially to hardening in a salt solution and cam spindles currently manufactured from CK 45 through cauterization based reshaping.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2004년도 봄 학술발표회 논문집
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• pp.397-408
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• 2004

The aim of this paper is to study the interaction between adjacent buildings with different foundation levels under earthquake loading conditions. Buildings and soil are represented by two different models. In the first case, the building itself is modeled with standard frame elements, whereas the soil behavior is simulated by a special grid model, In the second case, the building and soil are represented by plane stress or plane strain elements. The modulus of elasticity of the ground as well as the varying relations of inertia have a strong influence on the section forces within the buildings. The interaction between the two buildings is demonstrated and discussed via numerical examples using the proposed method.

• 아동학회지
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• 제12권1호
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• pp.38-51
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• 1991

This study investigated (1) the relation of aggressiveness to the outcome of conflict, intentional attribution, predicted response, and (2) friendship as a variable affecting intentional attribution and predicted response. The subjects are 78 fifth grade boys selected from a public elementary school located in Seoul. The children were individually tested by the researcher who read the items to the child. Dodge and Somberg's aggression questionnaire and Dodge and Frame's conflict outcome of ambiguosly intended stories were modified for use in this study. The instigator of aggression in the stories was classified as friend or non-friend and aggressive non-friend or nonaggressive non-friend. Two-way analyses of variance involving one between-subjects factor (aggression of subject) and one within-subjects factor (instigator combination) were performed on children's responses to three of the scales (hostile, neutral, positive). The results show that (1) there were differences in intentional attribution to the children's aggressiveness, regardless of the friendship status of the instigator, and (2) the predicted response to aggressiveness varied with type of instigator.

• 한국경영과학회지
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• 제30권2호
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• pp.29-40
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• 2005

In this research, we propose packet scheduling algorithm considering different QoS characteristics of real-time traffic and non-real-time traffic in the next generation wireless communication system serving the multimedia traffic and a new efficient framing method cooperated with this packet scheduler. When the selected traffic classes of the selected users are transmitted, our proposed framing method can increase the number of serviced traffic classes by mixing the many different traffic classes within one frame considering data rate decided by the allocated AMC (Adaptive Modulation and Coding) option. Using this proposed method, the fairness among the traffic classes can be achieved and the system performance for total throughput and delay can be enhanced. Simulations are performed to analyze the performance of the proposed framing method. Our proposed packet scheduler and framing method will be applied to the next generation multimedia wireless communication system serving many traffic classes.

• 한국멀티미디어학회논문지
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• 제10권6호
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• pp.737-744
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• 2007

This paper proposes the blind watermarking algorithm for digital video based on magnitude modulus subband in wavelet transform domain. After transforming each of frames into wavelet domain, the proposed algorithm divides LH, HL, and HH subbands of 2-level into $3{\times}3$ blocks and calculates average magnitude modulus of all blocks. Then the watermark bit is embedded into a target magnitude modulus comparing with an average magnitude modulus within a block. Experimental results were confirmed that the proposed algorithm has the good robustness against MPEG and frame attacks than the conventional algorithm.