• 설비공학논문집
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• 제20권5호
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• pp.321-326
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• 2008

This paper presents and analyzes the effects of on-grid electricity cost, fuel price and initial capital cost of a CHP system, on the optimum DG and AC capacity and NPV, by using the ORNL CHP Capacity Optimizer, which was applied to a library in a university. By considering the current domestic energy cost and initial capital cost, it is shown that the installation and operation of the CHP system is not economical. However, with the current domestic CHP installation cost and fuel price, the NPV achieved by the installation of CHP system is greater when the on-grid electricity price is a factor of ${\times}1.5$ the present value. Regarding the initial capital cost of the CHP system, the reduction of the DG cost is much more economical than that of the AC cost, with respect to NPV. Electricity cost and fuel price have opposite effects on NPV, and NPV is more sensitive to an increase of the electricity cost than an increase of the fuel price.

• 대한산업공학회지
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• 제2권1호
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• pp.85-92
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• 1976

In this paper, the employment planning model is developed which is a decision-making model for determining the optimum employment level with respect to varying net manpower requirement for each planing period such that total cost in a planning horizon is minimized. It is constructed as a nonlinear programming model and a dynamic programming model on the basis of studies in the areas of production smoothing and manpower scheduling. Costs for a planning period are categorized into regular wage cost, hiring cost, and overtime cost. The first is a linear function. The other two cost functions are of quadratic nature. The planning horizon of this planning model is intermediate range (five years) for which a fair planning accuracy can be guaranteed. The model considers learning period for each job class. It is simple and an optimum solution can be easily obtained by direct search techniques.

• 한국구조물진단유지관리공학회 논문집
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• 제6권4호
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• pp.189-199
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• 2002

This study is intended to propose a systematic procedure for the development of the conditional assessment based on the safety of structures and the cost effective performance criteria for designing and upgrading of bridge structures. As a result, a set of cost function models for a life cycle cost analysis of bridge structures is proposed and thus the expected total life cycle costs (ETLCC) including initial (design, testing and construction) costs and direct/indirect damage costs considering repair and replacement costs, human losses and property damage costs, road user costs, and indirect regional economic losses costs. Also, the optimum safety indices are presented based on the expected total cost minimization function using only three parameters of the failure cost to the initial cost (${\tau}$), the extent of increased initial cost by improvement of safety (${\nu}$) and the order of an initial cost function (n). Through the enough numerical invetigations, we can positively conclude that the proposed optimum design procedure for bridge structures based on the ETLCC will lead to more rational, economical and safer design.

• 한국건축시공학회지
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• 제14권5호
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• pp.415-422
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• 2014

본 연구는 공공건축물의 실적공사비 분석을 통해 총공사비에 대한 적정보정율을 기초자료로 제시하고자 한다. 이에 대해 조달청에서 발주한 2009~2011년에 준공된 53개 프로젝트를 연구 대상으로 하였다. 공사비 분석은 주요 공정인 건축, 기계, 전기, 통신, 부대시설에 대하여 빈도론적 관점에서 중위수를 활용한 절대오차율을 기반으로 총공사비에 대해 비교 분석하였다. 이를 통해 적합회귀모형을 선정하고 보정율을 책정하였다.

• 한국강구조학회 논문집
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• 제18권6호
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• pp.677-686
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• 2006

본 논문에서는 생애주기비용뿐만 아니라 생애주기성능 조건을 함께 고려하여 열화되는 교량의 최적 유지관리 전략 수립을 위한 보다 실제적이고 현실적인 방법을 제안하였다. 교량의 성능 및 비용과 관련된 다중목적 조합 최적화 문제인 교량 유지관리 시나리오 집합의 생성을 위해 유전자 알고리즘을 적용하였으며, 다중목적함수에 대한 최적의 균형 잡힌 유지관리 시나리오의 선정이 가능한 기법을 제안하였다. 최적 유지관리 시나리오는 부재수준뿐만 아니라 교량 시스템 수준에서도 생성 가능하도록 하였다. 실제 공용중인 교량에 적용하여 제안된 방법의 실 적용성을 검증하고 분석하였다. 제안된 방법은 기존의 유지관리방법의 한계를 극복하고, 실질적인 예방유지관리체계의 도입을 위한 교량 유지관리 의사결정에 활용될 수 있을 것으로 기대된다.

• 한국구조물진단유지관리공학회 논문집
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• 제11권4호
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• pp.109-120
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• 2007

본 연구에서는 생애주기비용을 고려한 성능기반 최적 유지관리 전략 수립 시스템을 개발하였다. 교량 수명동안 비용과 성능이라는 상반되는 목적을 균형있게 만족시킬 수 있는 유지관리 시나리오의 생성을 다중목적 조합최적화 문제로 정식화하고 유전자알고리즘을 적용하였다. 개발된 프로그램을 이용하여 국도 상 강거더 교량의 최적 유지관리 시나리오를 제공하는 과정을 제시하였다. 개발된 시스템은 현재의 교량 유지관리 전략 수립의 방법을 개선하여 교량 관리주체에게 다양한 제약 및 요구조건에 부합하는 최적의 교량 유지관리 시나리오를 제공할 수 있는 효율적인 도구로 활용될 수 있을 것으로 판단된다.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2009년도 하계학술발표대회 논문집
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• pp.325-331
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• 2009

In this paper, a simulation approach for the optimum design of cogeneration system is described. For the purpose of the systematic analysis, a simulation tool is developed with which the prediction of the energy load, calculation of operation data according to prime mover or capacity of it, and estimation of economic gains can be carried out. As for the criterion of the optimum design, the economic gains by adopting cogeneration system is taken. Based on the capital, operation, and maintenance costs etc, LCC analysis is to be carried out for the scenarios respectively. In this study, the simulation for the apartment complex is performed and the analysis of the results are described in detail. The effects of the operation parameters such as capital cost, fuel cost, and unit cost for the purchase or sale of heat and electricity on overall economy are also be considered by sensitivity study.

• 상하수도학회지
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• 제14권1호
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• pp.45-53
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• 2000

The optimum operation of domestic wastewater treatment plant can give influence on operational cost and future expansion in Korea where has 93 operational domestic wastewater treatment plants. Also, the study on optimum operation can reduce operation cost and budget of municipalities whom have responsibility of wastewater treatment plant operation. In this study, 9 domestic wastewater treatment plants which can represent 93 plants in Korea have been selected and operational data are gathered. The collected data are inputted to computer simulator based on IAWQ's Activated Sludge Model No.1 and optimum operation methods are developed. Also, the electric power for aeration which has large portion of overall operation cost are calculated based on design and operation conditions and these are compared. In this study, it was found that design wastewater characteristics are 1.6 times higher than those of daily maximum except for E plant and that estimation methods for design wastewater characteristics have to be improved. Based on computer simulation, we found there is no need to operate all aeration tanks due to weak influent overall power for aeration can be reduced to about 43% of design one.

• 한국항해학회지
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• 제5권1호
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• pp.1-23
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• 1981

As far as transportation problems are concerned, the minimization of transportation cost is the most prevailing object. But in some cases, the cargo delivery time is the utter problem rather than the cost. For instance, we may imagine the case that the delivery of the construction materials is delayed behind the schedule and this makes the construction cost increased because of idle time of other materials and man power, in addition to the indemnity. Therefore the allocation of ships, in marine transportation which is now the main route of overseas trade, to the needed area on the required time is to be appropriately performed. However, there are several restrictions for cargo delivery to meet the demand, such as ship's size, number to be employed and cargo handling capacity of the ports, etc. And there are some other factors to be considered, that is, the degree of necessities of commodities, on their kinds, amount, and the time of arrival, etc. This paper deals with the problem of optimum allocation of ships emphasizing the cargo delivery time adopting Linear Programming technique with those cargo delivery restrictions and factors transformed by introducing the multi-speed conception, the conversion of multi-commodity to a single commodity, allowable delivery time, weight penalty number and nominating priority. This paper presents a case of optimum allocation of ships in the light of cargo delivery time for a construction company which has two different construction places and analyzes the result. This study will give a planner a good tool for optimum planning of maring transportation and be used for decision of schemes.

• Journal of Biosystems Engineering
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• 제12권1호
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• pp.31-38
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• 1987

In order to improve the traditional post harvest system in Korea, a model for mechanized rice drying and storage system was developed and introduced as the first part of the study(Park, 1986). As the second part of the study, capital requirement and cost of the model system was analyzed. Also, optimum size of the model system was estimated by comparing with the traditional harvest system. From the study, the following results can be concluded: 1. The capital requirement of the model system decreases as the model size increases. For example, a model system having 500 ton storage capacity requires 439,000 Won/ton. However it requires 313,200 Won/ton only, if the model size increases to 1000 ton. 2. Also, total cost of the model system decreases as the model size increases. For example, total costs of the model system having 500 ton and 1000 ton storage capacity are 101,208 Won/ton and 69,320 Won/ton, respectively. 3. The breakeven point (optimum size) of the model can be estimated around 630 ton storage capacity if the operation rate is assumed as 100%. However, the optimum size of the model is 710 ton, if the operation rate it assumed 80%.