• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.273-279
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• 2011

Concerns over the environment have spawned a number of research studies in the construction industry, as the construction of built environments and large infrastructures involves diverse environmental impacts and loads of hazardous emissions. Many researchers have attempted to quantify these environmental loads, including greenhouse gases, carbon dioxide, nitrogen dioxide, and sulfur dioxide, to name a few. However, little research has been conducted regarding integrating the life-cycle assessment (LCA) of environmental loads with the current life-cycle cost analysis (LCCA) approach. This study aims to estimate the environmental loads as a monetary value using the European Climate Exchange (ECX) rate and, then, to integrate those impacts with the pure construction cost. Toward this end, this study suggests an integrated approach that takes into account the environmental effect on the evaluation of the life-cycle cost (LCC). The bill of quantity (BOQ) data of a real highway project are collected and analyzed for this purpose. As a result, considering the environmental loads in the pavement process, the total LCC increased 16% from the traditional LCC cost. This study suggests an integrated approach that will account the environmental effect on the LCC. Additionally, this study is expected to contribute to better decision-making, from the perspective of more sustainable development, for government as well as for contractors.

• 전자공학회논문지 IE
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• 제46권3호
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• pp.33-41
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• 2009

본 논문에서는 Limit-cycle 항법의 안정성을 분석하고 path follwer를 제안한다. Limit-cycle 항법은 2차 비선형 함수의 특징을 이용하며, 빠른 이동로봇의 움직임을 제어하기 위해 제안되어졌다. Limit-cycle의 수렴반경과 방향을 조절하여 충돌 없이 장애물을 회피하고, 목표점에 도달할 수 있다. 하지만 지금까지 Limit-cycle 항법의 안정성은 연구되어지지 않았다. 따라서 본 논문에서는 이러한 안정성을 분석하고, Limit-cycle 항법을 로봇축구에 적용하여, 시뮬레이션과 실제 실험에서 제안된 방법을 검증한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.1035-1036
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• 2010

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1471-1479
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• 2015

A major portion of the capital costs in the present day power transmission systems are due to the cost of equipment and construction process. Transmission utilities in the recent years are drawing greater attention towards performing life cycle costing studies for cost management and decision making. However, the data involved in these studies are highly uncertain and the effect of these uncertainties cannot be directly included in the study process, resulting in inaccurate solutions. Interval mathematics provides a method for including these uncertainties throughout the cost analysis and provides final solution range in the form of intervals. In this regard, it is essential and extremely important that significant research has to be carried out in understanding the principles of life cycle costing methodology and its applicability to cost analysis of transmission lines along with uncertainties involved in the cost assessment process. In this paper, economic analysis of power transmission lines using interval mathematics has been studied. Life cycle costing studies are performed using net present value analysis on a range transmission lines used in India and the results are analyzed. A cost break even analysis considering right of way costs was carried out to determine the point of economy indifference.

• Nuclear Engineering and Technology
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• 제45권5호
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• pp.653-664
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• 2013

The design of computer-based instrumentation and control (I&C) systems is determined by the allocation of I&C functions to I&C systems and components. Due to the characteristics of computer-based technology, component failures can negatively affect several I&C functions, so that the reliability proof of the I&C systems requires the accomplishment of I&C system design analyses throughout the I&C life-cycle. On one hand, this paper proposes the restructuring of the sequential IEC 61513 I&C life-cycle according to the V-model, so as to adequately integrate the concept of verification and validation. On the other hand, based on a metamodel for the modeling of I&C systems, this paper introduces a method for the modeling and analysis of the effects with respect to the superposition of failure combinations and event sequences on the I&C system design, i.e. the temporal change of physical structure is analyzed. In the first step, the method is concerned with the modeling of the I&C systems. In the second step, the method considers the analysis of temporal change of physical structure, which integrates the concepts of the diversity and defense-in-depth analysis, fault tree analysis, event tree analysis, and failure mode and effects analysis.

• 대한기계학회논문집B
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• 제24권9호
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• pp.1219-1226
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• 2000

An efficient method is developed for plunger thermal cycle analysis in repeated forming process of the TV glass. The plunger undergoes temperature fluctuation during a cycle due to the repeated contact and separation from the glass, which attains a cyclic steady state having same temperature history at every cycle. Straightforward analysis of this problem brings about more than 80 cycles to get reasonable solution, and yet hard to setup stopping criteria due to extremely slow convergence. An exponential fitting method is proposed to overcome the difficulty, which finds exponential function to best approximate temperature values of 3 consecutive cycles, and new cycle is restarted with the fitted value at infinite time. Numerical implementation shows that it reduces the number of cycles dramatically to only 6-18 cycles to reach convergence within 10 accuracy. A system for the analysis is constructed, in which the thermal analysis is performed by commercial software ANSYS, and the fitting of the result is done by IMSL library. From the parametric studies, one reveals some important facts that although the plunger cooling or the glass thickness is increased, its counter part in contact is not much affected, duo to the low thermal conductance of the glass.

• Journal of Advanced Marine Engineering and Technology
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• 제24권1호
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• pp.41-48
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• 2000

The characteristics of a combined cycle for the production of fresh water and air-conditioning was analyzed. The combined cycle consisted of an open water cycle and a $CO_2$ refrigeration cycle interlinked in the pre-heater of the water cycle, which is the condenser of the refrigeration cycle. The oprating conditions and criteria for the fresh water production and air-conditioning was described and their effects on the total system were evaluated. The results indicated an increase of desalinated water with the increase of hot water temperature, which resulted in the decrease of cooling capacity of the refrigeration system in this study. However, the energy saving correspond to the pre-heating of the water cycle by the condensing of the refrigeration system shows the avilable advantage of the proposed cycle as compared to other single purpose plants for desalination.

• Journal of Advanced Marine Engineering and Technology
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• 제29권8호
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• pp.946-952
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• 2005

The $CO_{2}$ refrigeration cycle is expected to reduce the compressor work and increase the COP by applying two-phase ejector as a device for the recovery of dissipated expansion energy. In this study, the performance of the cycle was simulated and effects of the ejector shapes on the performance of the $CO_{2}$ refrigeration cycle were investigated. The following results were obtained through the cycle simulation. The COP of the $CO_{2}$ refrigeration cycle with two-phase ejector flow which expansion is occured in the isentropic manner is increased by a maximum of 24 $\%$ than the basic cycle with expansion valve If the velocity nonequilibrium in the mixing process is assumed the COP of the cycle is increased with the increase of the length and the decrease of the section area of the mixing tube. The best cycle performance is obtained when the divergent angle of diffuser is 7.

• 대한산업공학회지
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• 제42권3호
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• pp.241-248
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• 2016

Plant life cycle consists of design, construction, certification, operation, and maintenance phases, and various and enormous plant life cycle data is involved in each phase. Plant life cycle data should be linked with each other based on its proper relationships, so that plant operators can access necessary plant data during their regular operations and maintenance works. Currently, the relationships of plant life cycle data may not be defined explicitly, or they are scattered over several plant information systems. This paper proposes high level design of a plant life cycle data management system based on pre-defined plant life cycle database design. ISO-15926 standard is adapted for the database design. User-interface designs of the plant life cycle data management system are explained based on analysis of plant owners' requirements. A conceptual design of the database is also described with the entity-relationship diagram.

• 한국건설관리학회논문집
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• 제2권2호
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• pp.59-67
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• 2001

본 연구는 사례연구를 통해서 강박스교와 PSC박스교의 생애주기비용(LCC)을 분석하여 경제성을 평가하는데 목적이 있다. 본 연구에서는 유지관리비를 산출하기 위해 보수 및 교체주기에 대한 설문조사를 실시하였으며, 교량 형식별 LCC 분석 및 비교에는 현재가치 법을 이용하였다. 본 연구의 수행 결과를 요약하면 다음과 같다. (1) 사례 연구를 통해 강박스교와 PSC박스교의 LCC 분석모델을 제시하였다. (2) 설문조사를 실시하여 강박스교와 PSC박스교 부속물의 보수 및 교체주기를 산정하였다. (3) LCC 사례 연구 결과, PSC박스교가 강박스교보다 경제적인 것으로 분석 되었다.