• Structural Engineering and Mechanics
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• 제75권6호
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• pp.747-769
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• 2020

This paper provides a semi-analytical approach to investigate the variations of 3D displacement components, electric potential, stresses, electric displacements and transverse vibration frequencies in laminated piezoelectric composite plates based on the scaled boundary finite element method (SBFEM) and the precise integration algorithm (PIA). The proposed approach can analyze the static and dynamic responses of multilayered piezoelectric plates with any number of laminae, various geometrical shapes, boundary conditions, thickness-to-length ratios and stacking sequences. Only a longitudinal surface of the plate is discretized into 2D elements, which helps to improve the computational efficiency. Comparing with plate theories and other numerical methods, only three displacement components and the electric potential are set as the basic unknown variables and can be represented analytically through the transverse direction. The whole derivation is built upon the three dimensional key equations of elasticity for the piezoelectric materials and no assumptions on the plate kinematics have been taken. By virtue of the equilibrium equations, the constitutive relations and the introduced set of scaled boundary coordinates, three-dimensional governing partial differential equations are converted into the second order ordinary differential matrix equation. Furthermore, aided by the introduced internal nodal force, a first order ordinary differential equation is obtained with its general solution in the form of a matrix exponent. To further improve the accuracy of the matrix exponent in the SBFEM, the PIA is employed to make sure any desired accuracy of the mechanical and electric variables. By virtue of the kinetic energy technique, the global mass matrix of the composite plates constituted by piezoelectric laminae is constructed for the first time based on the SBFEM. Finally, comparisons with the exact solutions and available results are made to confirm the accuracy and effectiveness of the developed methodology. What's more, the effect of boundary conditions, thickness-to-length ratios and stacking sequences of laminae on the distributions of natural frequencies, mechanical and electric fields in laminated piezoelectric composite plates is evaluated.

• 디지털콘텐츠학회 논문지
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• 제15권1호
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• pp.45-52
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• 2014

모든 의료정보시스템에는 이해관계자와 환경이 존재한다. 의료정보시스템 개발 시에는 이 같은 환경에서 사용자의 기능적 요구사항과 비기능적 요구사항인 품질을 만족시켜야할 목표가 있다. 이 목표를 달성하기 위하여 현재 다양한 방법으로 정보시스템 개발이 이루어지고 있고 다양한 애플리케이션이 등장하고 있다. 그러나 이 같은 의료정보시스템 개발의 과정에서 기본적인 요구조건을 만족하고 있는지는 별도의 관점에서 고찰하지 않으면 안 된다. 본 연구는 유-헬스케어 서비스 소프트웨어아키텍쳐 품질확보를 위한 요구사항 분석방법을 제안한다. 의료정보시스템의 요구사항 분석을 통해 소프트웨어아키텍처 품질평가 사항과 의료정보서비스 품질평가 연계지표 평가방식을 제안했다. 이 방법은 연계성 팩터의 품질 합계치를 산출하고 그 추이를 분석하므로서 유-헬스케어 소프트웨어아키텍쳐에 대한 종합평가가 가능하게 한다. 품질평가는 요구사항 분석에서 도출된 목표와 비교하여 달성도를 분석하며 만족도 수준이 미진한 분야를 발췌하여 원인분석 및 개선작업에 활용이 가능하다.

• 한국BIM학회 논문집
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• 제6권3호
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• pp.1-14
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• 2016

The usage of Building Information Modelling (BIM) in building projects has enabled improvement in project planning, implementation and collaboration process amongst various stakeholders within architecture, engineering and construction (AEC) industry. However, variations exist in the current practices of BIM implementation and coordination process in the industry. These variations result in inconsistent degree of BIM use across the construction industry. This inconsistency gives rise to several managerial and technological challenges such as data interoperability issues and purposeful integration and exchange of information within the BIM components. In order to tackle the issue, it is essential to analyse the different BIM approaches employed by the industry practitioners. BIM guidelines serve as a critical link between the BIM model, and its subsequent execution. They therefore provide the best reflection of BIM application and processes. This research paper aims to address the variations existing in BIM practices across the construction industry. It includes an extensive study of 21 existing, publicly available BIM-based guidelines in order to establish an understanding of the present state of practice and deduce issues and concerns related to them. All guidelines analysed in this paper are first categorised based on authorship and the release date for efficient comparison. The points of similarity and difference between them are thereby realized and outlined. In addition, the transition of project implementation process from traditional methods to BIM technology is also explained. The existence of inconsistencies in the BIM guidelines reviewed in this paper reflects the need of a BIM 'Code Compliance Check'. The Code Compliance Check will serve as a regulatory project guideline that will further improve the potential of BIM by incorporating a consistent BIM modelling methodology for the entire construction industry.

• 한국실내디자인학회논문집
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• 제16권6호
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• pp.189-196
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• 2007

The purpose of this study is to make a comparative analyzation toward abstracted emotional properties appeared in the museum exhibition spaces designed by the three masters of the modern architecture;Frank Lloyd Wright, Le Corbusier and Mies van der Rohe. In addition, this study will also aim to inquire into how the emotional properties have affected the third generation architects. It is especially expected that the 'emotional tendency' emerging in various fields of the present time can serve as useful information through the analysis of emotional design properties appeared in the exhibition space which is directly linked with the human lives. In order to achieve the purpose of the study, in New York by Wright, in Tokyo by Le Corbusier and in Berlin by Mies Van der Rohe were selected. As for the analyzation methodology to be adopted for deriving the aiming points at the emotional design, five criteria of analyzation have been established in order to understand the properties of the emotional area: they are (1) spatial affordance, (2) human congeniality, (3) emotional factors of the area, (4) constitution of the area and (5) expressive division of the area. Using these criteria, this study will reveal what are some of the emotional characteristics shown in each museums and its analytical result will be useful to apply to future museum design. It is especially expected that the 'emotional tendency' emerging in various fields of the present time can serve as useful information through the analysis of emotional design properties appeared in the exhibition space of design which is directly linked with the human behavior.

• 한국정보과학회논문지:시스템및이론
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• 제30권10호
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• pp.595-602
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• 2003

본 논문은 표준 셀을 효율적으로 배치하는 하이브리드 기법을 제시한다. 제시한 기법에서는 레이아웃 영역을 n${\times}$m 그리드로 분할하고, 분할된 그리드의 각 빈에 셀을 배치함으로 광역 배치를 얻는다. 광역배치를 얻은 후 Relaxation-Based Local Search (RBLS)라 불리는 해석적 최적 기법[12］을 사용하여 배치를 개선시킨다. 이 기법을 사용하면 배치 전체를 개괄적으로 볼 수 있게 되어 배치가 국부 최적에 빠지지 않도록 할 수 있다. 이 기법의 핵심은 중복을 해결하기 위한 매우 효율적인 적법화 알고리즘이라고 볼 수 있는데, 이에 대해 본 논문은 자세히 설명한다. 광역배치가 더 이상 개선되지 않으면 이를 상세 배치로 변환시킨다. 상세 배치를 얻은 후“최적 인터리빙”이라 불리는 기법[13］을 사용하여 이를 더욱 개선시킨다. MCNC 벤치마킹 회로에 대한 실험 결과는［14]에서 보여준 Feng Shui의 결과와 필적할 만하다.

• KIEE International Transactions on Power Engineering
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• 제5A권1호
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• pp.85-92
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• 2005

In this paper, Nash equilibriums of generation markets are investigated using a game theory application for simplified competitive electricity markets. We analyze the characteristics of equilibrium states in N-company spot markets modeled by uniform pricing auctions and propose a new method for obtaining Nash equilibriums of the auction. We assume that spot markets are operated as uniform pricing auctions and that each generation company submits its bids into the auction in the form of a seal-bid. Depending on the bids of generation companies, market demands are allocated to each company accordingly. The uniform pricing auction in this analysis can be formulated as a non-cooperative and static game in which generation companies correspond to players of the game. The coefficient of the bidding function of company-n is the strategy of player-n (company-n) and the payoff of player-n is defined as its profit from the uniform price auction. The solution of this game can be obtained using the concept of the non-cooperative equilibrium originating from the Nash idea. Based on the so called residual demand curve, we can derive the best response function of each generation company in the uniform pricing auction with N companies, analytically. Finally, we present an efficient means to obtain all the possible equilibrium set pairs and to examine their feasibilities as Nash equilibriums. A simple numerical example with three generation companies is demonstrated to illustrate the basic idea of the proposed methodology. From this, we can see the applicability of the proposed method to the real-world problem, even though further future analysis is required.

• 대한교통학회지
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• 제30권2호
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• pp.127-136
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• 2012

다중추돌사고의 형태는 연쇄 추돌이라고 불리우는 뒤로부터의 순차적인 추돌과 앞으로부터의 순차적인 추돌, 그리고 순서가 섞여 있는 추돌형태로 구분된다. 다중추돌사고에 대하여 몇가지 효과적인 재구성 해석 방안을 제시한다. 브레이크 다이브 등으로 인한 차량 파손과 승객 부상을 활용하는 전통적인 경험적 수법과 강체역학 범주내에서의 이론적인 해석 결과를 구하여 당장에의 실용적인 적용이 가능하도록 하였다. 국내에 보급이 확산되고 있는 영상사고기록장치를 활용하고 시뮬레이션 프로그램 등을 병행 활용하여 다중추돌사고를 효과적으로 해석하는 방안을 제시하였다. 저장 동영상에 대한 단순 직관적인 조사를 넘어설 수 있도록 동영상 분석 결과에 근거한 시뮬레이션 해석을 수행하여 다중추돌사고에 대한 구체적이고 다양한 정보의 획득을 가능하게 하여 원인 규명 및 책임 소재 등을 명확하게 구분할 수 있도록 하였다.

• 산경연구논집
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• 제5권4호
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• pp.31-42
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• 2014

Purpose - According to the applied studies knowledge, management implementation can improve organizational performance. The main objective of this study is to develop an understanding of critical success factors that enhance the successful implementation of knowledge management. Research design, data, and methodology - This study used Analytical Hierarchy Procedure (AHP), which is a multi-criteria decision making model that works on fuzzy logic. Using this method, researchers can find the proportion of success due to the contribution of the critical success factors (CSFs). Results - The results show that more than 70% of respondents indicate the possibility of success in knowledge management implementation. Further, the results show that top management support has the greatest relationship with the success of knowledge management implementation. This was followed by information technology, performance measurement, and culture, which had a high relation with knowledge management success. Process and activities have a moderate positive relation, while education and training has a low relation with success. Because of an inappropriate p-value, knowledge management strategies show no relation to the success of knowledge management in the Iranian health Industry. Conclusions - This study was conducted because of a critical issue in the Iranian health industry that indicated that a significant portion of the workforce would retire in 5 to 10 years. Most highly experienced and knowledge oriented employees would become eligible for retirement. Therefore, knowledge management is presented as a complete solution in the Iranian health sector.

• Structural Engineering and Mechanics
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• 제55권6호
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• pp.1261-1278
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• 2015

Due to their low intrinsic damping, stay cables in cable-stayed bridges have often exhibited unanticipated and excessive vibrations which result in increasing maintenance frequency and disruption to normal operations of the entire bridges. Mitigation of undesired cable vibration can be achieved by attaching an external damping device near the anchorage. High Damping Rubber (HDR) dampers have many advantages such as compact size, better aesthetics, easy maintenance, temperature stability, and cost benefits; therefore, they have been widely used to increase cable damping. Although a single damper has been shown to reduce cable vibrations, it is not the most effective method due to geometric constraints. This paper proposes the use of two HDR dampers to improve effectiveness and robustness in suppressing cable vibration. Oscillation parameters of the cable-dampers system were investigated in detail by modeling the stay cable as a taut string and each HDR damper as complex-valued impedance and by using an analytical formulation of the complex eigenvalue problem. The problem of two HDR dampers arbitrarily located along a cable is solved and the solution is discussed. Asymptotic formulas to calculate the damping ratios of the cable with two HDR dampers installed near the anchorage(s) are proposed and compared with the exact solutions. Further, a design example is presented in order to justify the methodology. The results of this study show that when the two HDR dampers are installed close to each other on the same end of the cable, some interaction between the dampers leads to reduced damping ratio. When the dampers are on the opposite ends of the cable, they are effective in increasing damping ratio and can provide better vibration reduction to multiple modes.

• 대한교통학회:학술대회논문집
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• 대한교통학회 1997년도 제32회 학술발표회
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• pp.35-72
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• 1997

This study was conducted to develop a methodology to predict utility pole accident rates and to evaluate cost-effectiveness for safety improvement for utility pole accidents. The utility pole accident rate prediction model was based on the encroachment rate approach introduced in the Transportation Research Board special Report 214. The utility pole accident rate on a section of highway depends on the roadside encroachment rate and the lateral extent of encroachment. The encroachment rate is influenced by the horizontal and vertical alignment of the highway as well as traffic volume and mean speed. The lateral extent of encroachment is affected by the horizontal and vertical alignment, the mean speed and the roadside slope. An analytical method to generate the probability distribution function for the lateral extent of encroachment was developed for six kinds of encroachment types by the horizontal alignment and encroachment direction. The encroachment rate was calibrated with the information on highway and roadside conditions and the utility pole accident records collected on the sections of 55mph speed limit of the State Trunk Highway 12 in Wisconsin. The encroachment rate on tangent segment was calibrated as a function of traffic volume with the actual average utility pole accident rates by traffic volume strategies. The adjustment factors for horizontal and vertical alignment were when derived by comparing the actual average utility pole accident rates to the estimations from the model calibrated for tangent and level sections. A computerized benefit-cost analysis procedure was then developed as a means of evaluating alternative countermeasures. The program calculates the benefit-cost ratio and the percent of reduction of utility pole accidents resulting from the implementation of a safety improvement. This program can be used to develop safety improvement alternatives for utility pole accidents when a predetermined performance level is specified.