• 산업경영시스템학회지
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• 제35권1호
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• pp.198-213
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• 2012

Navy ship acquisition management business contributed to the korean Navy and defense exports with government suppliers in Korea for over 40 years. But due to advanced technology, development trend of Navy ship and defense export requirements, it enable to make a contribution to a better system improvement are being demanded. In this paper, an adjective Navy ship acquisition process is presented in order to improve the acquisition process takes the first step for acquisition planning process to enhance the efficiency and rationality that is based on consensus of Navy ship expert and experienced. In addition, systems engineering (SE) and quality control (QC) techniques based on Modeling and Simulation are investigated to carry out efficient project management and scientific quality control system in Navy ship acquisition process. Finally, it is suggested to apply SE/QC based on M&S for Navy ship acquisition process using civilian infrastructure and organizations in order to take advantage of the world's leading domestic industry based on considering the difficult conditions of Navy ship suppliers.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권4호
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• pp.1192-1207
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• 2014

Dynamic spectrum sharing is a key technology to improve spectrum utilization in wireless networks. The elastic spectrum management provides a new opportunity for licensed primary users and unlicensed secondary users to efficiently utilize the scarce wireless resource. In this paper, we present a game-theoretic framework for dynamic spectrum allocation where the primary users rent the unutilized spectrum to the secondary users for a monetary profit. In reality, due to the ON-OFF behavior of the primary user, the quantity of spectrum that can be opportunistically shared by the secondary users is limited. We model this situation with the renewal theory and formulate the spectrum pricing scheme with the Bertrand game, taking into account the scarcity of the spectrum. By the Nash-equilibrium pricing scheme, each player in the game continually converges to a strategy that maximizes its own profit. We also investigate the impact of several properties, including channel quality and spectrum substitutability. Based on the equilibrium analysis, we finally propose a decentralized algorithm that leads the primary users to the Nash-equilibrium, called DST. The stability of the proposed algorithm in terms of convergence to the Nash equilibrium is also studied.

• Steel and Composite Structures
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• 제47권3호
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• pp.423-436
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• 2023

In this research, we tested 10 simply supported concrete-encased composite columns under monotonic eccentric loads and investigated their shear behaviour. The specimens tested were two reinforced concrete specimens, three steel-reinforced concrete (SRC) specimens with an H-shaped steel section (also called a beam section), and five SRC specimens with a cruciform-shaped steel section (also called a column section). The experimental variables included the transverse steel shape's depth and the longitudinal steel flange's width. Experimental observations indicated the following. (1) The ultimate load-carrying capacity was controlled by web compression failure, defined as a situation where the concrete within the diagonal strut's upper end was crushed. (2) The composite effect was strong before the crushing of the concrete outside the steel shape. (3) We adjusted the softened strut-and-tie SRC (SST-SRC) model to yield more accurate strength predictions than those obtained using the strength superposition method. (4) The MSST-SRC model can more reasonably predict shear strength at an initial concrete softening load point. The rationality of the MSST-SRC model was inferred by experimentally observing shear behaviour, including concrete crushing and the point of sharp variation in the shear strain.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권9호
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• pp.1544-1572
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• 2011

Task placement and scheduling are traditionally studied in following aspects: resource utilization, application throughput, application execution latency and starvation, and recently, the studies are more on application scalability and application performance. A methodology for task placement and scheduling centered on tasks based on virtual machines is studied in this paper to improve the performances of systems and dynamic adaptability in applications development and deployment oriented parallel computing. For parallel applications with no real-time constraints, we describe a thought of feature model and make a formal description for four layers of task placement and scheduling. To place the tasks to different layers of virtual computing systems, we take the performances of four layers as the goal function in the model of task placement and scheduling. Furthermore, we take the personal preference, the application scalability for a designer in his (her) development and deployment, as the constraint of this model. The workflow of task placement and scheduling based on virtual machines has been discussed. Then, an algorithm TPVM is designed to work out the optimal scheme of the model, and an algorithm TEVM completes the execution of tasks in four layers. The experiments have been performed to validate the effectiveness of time estimated method and the feasibility and rationality of algorithms. It is seen from the experiments that our algorithms are better than other four algorithms in performance. The results show that the methodology presented in this paper has guiding significance to improve the efficiency of virtual computing systems.

• Geomechanics and Engineering
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• 제30권6호
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• pp.503-515
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• 2022

The permeability coefficient is an essential parameter for the study of seepage flow in fractured rock mass. This paper discusses the feasibility and application value of using readily available RQD (rock quality index) data to estimate mine water inflow and grouting quantity. Firstly, the influence of different fracture frequencies on permeability in a unit area was explored by combining numerical simulation and experiment, and the relationship between fracture frequencies and pressure and flow velocity at the monitoring point in fractured rock mass was obtained. Then, the stochastic function generation program was used to establish the flow analysis model in fractured rock mass to explore the relationship between flow velocity, pressure and analyze the universal law between fracture frequency and permeability. The concepts of fracture width and connectivity are introduced to modify the permeability calculation formula and grouting formula. Finally, based on the on-site grouting water control example, the rock mass quality index is used to estimate the mine water inflow and the grouting quantity. The results show that it is feasible to estimate the fracture frequency and then calculate the permeability coefficient by RQD. The relationship between fracture frequency and RQD is in accordance with exponential function, and the relationship between structure surface frequency and permeability is also in accordance with exponential function. The calculation results are in good agreement with the field monitoring results, which verifies the rationality of the calculation method. The relationship between the rock mass RQD index and the rock mass permeability established in this paper can be used to invert the mechanical parameters of the rock mass or to judge the permeability and safety of the rock mass by using the mechanical parameters of the rock mass, which is of great significance to the prediction of mine water inflow and the safety evaluation of water inrush disaster management.

• 콘크리트학회논문집
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• 제28권1호
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• pp.75-84
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• 2016

이 연구의 목적은 삼각망 철근상세를 갖는 중실 철근콘크리트 기둥의 성능을 파악하는데 있다. 제안된 철근상세는 경제성과 합리성을 갖으며 공사기간의 단축을 가져올 수 있다. 삼각망 철근상세를 갖는 중실 철근콘크리트 기둥 실험체에 일정 축하중 하에서 횡방향 반복하중을 가하는 준정적 실험을 수행하였다. 사용된 프로그램은 철근콘크리트 구조물의 해석을 위한 RCAHEST이다. 사용된 해석기법은 조사된 실험체에 대하여 하중단계에 따라 성능을 비교적 정확하게 예측하였다. 그 결과 제안된 삼각망 철근상세는 기존 철근상세와 동등 이상의 소요성능을 보임을 확인하였다.

• 문화기술의 융합
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• 제3권4호
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• pp.131-136
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• 2017

본 논문에서는 기업 디자인의 개발 절차에 대한 이론적 고찰을 통해 마케팅 과정으로서 기업 디자인의 역할을 알아본다. 기업 디자인은 대상이 가지는 무형의 소비자 need를 개념화하여 기업 디자인의 전략의 역할을 확립할 수 있게 한다. 이 기업 디자인 접근방식을 마케팅적 접근법과 같이 조직화하여 디자인 결과물을 제작한다. 상업 디자인화와 시각화 과정을 통해 결과물의 정체성을 표현하고, 결과물을 직 간접 경험으로 최적화하기 위한 연구를 수행하였다. 디자인 결과물에 대한 과정을 통해 기업 디자인을 합리적으로 바라보며, 이를 통해 본질적으로 디자인은 창의성을 갖게 된다. 본 연구를 통해 디자인 프로세싱을 상세하게 제시하며, 최종 단계의 창의적인 디자인 전략 근거를 제시하고, 디자인을 자료 중심 개념으로 창의적이고 조화롭게 수행하는 이상적인 기업 디자인 방향성을 제시한다.

• Earthquakes and Structures
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• 제19권5호
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• pp.395-409
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• 2020

With verifications through many relevant researches in the past few decades, adopting the equivalent lateral force procedure for designing seismically isolated structures as a preliminary or even final design approach has become considerably mature and publicly acceptable, especially for seismic isolation systems that mechanically exhibit bilinear hysteretic behavior. During the design procedure, in addition to a given seismic demand, structural designers still need to previously determine three parameters, such as mechanical properties of seismic isolation systems or design parameters and performance indices of seismically isolated structures. However, an arbitrary or improper selection of given parameters might cause diverse or even unacceptable design results, thus troubling structural designers very much. In this study, first, based on the criterion that at least either two design parameters or two performance indices of seismically isolated structures are decided previously, the rationality and applicability of design results obtained from different conditions are examined. Moreover, to consider variations of design parameters of seismically isolated structures attributed to uncertainties of mechanical properties of seismic isolation systems, one of the conditions is adopted to perform bounding analysis for seismic isolation design. The analysis results indicate that with a reasonable equivalent damping ratio designed, considering a specific variation for two design parameters (the effective stiffness and equivalent damping ratio) could present more conservative bounding design results (in terms of isolation displacement and acceleration transmissibility) than considering the same variation but for two mechanical properties (the characteristic strength and post-yield stiffness).

• 한국지반환경공학회 논문집
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• 제14권8호
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• pp.45-51
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• 2013

분진, 소음, 진동 등 열악한 환경을 가진 지하구조물 건설현장에서는 작업자의 위치추적 및 원활한 감독자의 작업 전달과 함께 위험사고 발생 시 신속한 건설현장의 작업자 구출 등을 위한 기술개발이 절실히 요구되고 있다. 본 연구에서는 MEMS INS와 기압센서를 이용하여 지하공간 작업자들의 위치정보를 확보하기 위해 건설현장 테스트를 실시하였고, 검출된 결과를 바탕으로 위치 및 표고에 대한 정확도 분석을 수행하여 그 활용성에 대한 검증을 하였다. 연구수행결과 4km 구간에 대하여 작업자의 수평위치정확도는 10m 이내로 발생하였으며, 수직위치정확도의 경우 4m 이내로 층간 구분이 가능한 수준까지 위치정확도를 확보할 수 있어 지하구조물 건설현장에서의 활용성이 충분한 것으로 분석되었다.

• 대한토목학회논문집
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• 제38권5호
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• pp.703-711
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• 2018

최근 다양한 도시철도 노선이 건설되고, 주변노선과 연계가 이루어짐에 따라 도시철도 이용률이 증가하고 있다. 하지만, 정부는 여전히 기존의 획일적인 운임정책을 고수하고 있어, 다양한 이용패턴에 체계적인 대응을 하지 못할 뿐만 아니라, 공공성 위주의 운임정책으로 인해 운영사의 수익성 악화라는 구조적 문제점이 발생하고 있다. 본 연구는 도시철도 운임정책의 합리성을 제고하기 위해 일본, 영국 등 주요 선진국의 도시철도 운임정책을 검토하였다. 운임정책에 대한 체계적인 분석을 위해 운임결정방식, 카드운임에 대한 할인제도, 운임구조, 그리고 정부 보조금 정책 등의 관점에서 살펴보았으며, 이를 토대로 대한민국 수도권 도시철도 운임정책의 문제점 및 개선방안을 도출하였다. 본 연구를 통해 도시철도 서비스 수준과 수익성에 부합하는 적정 요금정책을 수립하여 합리적인 도시철도 운영에 도움을 줄 수 있을 것으로 기대한다.