• 품질경영학회지
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• 제39권2호
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• pp.170-178
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• 2011

In general, a software fault detection phenonenon is described by a software reliability model based on a nonhomogeneous Poisson process(NHPP). In this paper, we propose a software reliability growth model considering the differences of the software environments in both the testing phase and the operational phase. Also, we consider the problem of determining the optimal release time and the optimal warranty period that minimize the total expected software cost which takes account of periodic software maintenance(e.g. patch, update, etc). Finally, we analyze the sensitivity of the optimal release time and warranty period based on the fault data observed in the actual testing process.

• 방송공학회논문지
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• 제24권2호
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• pp.251-263
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• 2019

최근 인터넷 미디어 스트리밍 수요의 증가로 인해 CDN(Content Delivery Network) 비용이 크게 증가하였으며 이를 절감하기 위한 방안의 필요성이 날로 증가하고 있다. 이러한 상황에 맞춰 최근 CDN 비용을 절감할 수 있는 WebRTC(Web Real-Time Communication) 표준 기반의 P2P(Peer-to-Peer) 통신을 병용하는 DASH(Dynamic Adaptive Streaming over HTTP) 기술이 등장하였다. 본 논문에서는, 전달 이력에 기반하여 피어(peer)를 선택하게 함으로써, 이 기술의 CDN 비용 절감 효과를 크게 개선할 수 있는 새로운 알고리듬을 제안하였다. 또한 실험실 내에서 실제 이 알고리듬을 구현하고 모바일 네트워크 환경과 유사한 환경 조건에서 실험을 시행하여 그 성능을 측정한 결과, 무작위로 피어를 선택하는 기존의 시스템과 비교하여 더 높은 CDN 비용 절감 효과를 달성할 수 있음을 보였다.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1183-1188
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• 2009

Estimating project costs during the early stage of conceptual planning is very important when deciding whether to approve the project and allocate an appropriate budget. However, due to greater uncertainties involved in a project, it is challenging to estimate costs during this initial stage within a reasonable tolerance. This paper attempts to develop a cost-estimate model for public road projects under these circumstances and limitations. In the conceptual planning stage of a road project, there is only limited information for cost estimation, for example, such input data as total length of the route, origin and destination, number of lanes, general geographic characteristics of the route, and other basic attributes. This implies that the model should individuate suitable but restricted information without considering detailed features such as quantity of earthwork and a detailed route of a given condition. With these limited facts, this paper applies a case-based reasoning (CBR) method to solve a new problem by deriving similar past problems, which in turn is used to estimate the cost of a given project based on best-fitted previous cases. To develop a CBR cost-estimate model, the authors classified 8 representative variables, including project type, the number of lanes, total length, road design grades, etc. Then, we developed the CBR model, primarily by using 180 actual cases of public road projects, procured over the last decade. With the CBR model, it was found that the degree of error in estimation can be reasonably reduced, to below approximately 30% compared to the final costs estimated upon the completion of detailed design.

• 한국건설관리학회논문집
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• 제17권4호
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• pp.95-102
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• 2016

공기연장에 따른 간접비 산정에 관한 연구가 최근 정량적인 부분에 집중되어 제시되고 있으며, 최근 제도개선에 관한 연구가 계속적으로 이루어지고 있다. 국내 공공 공사의 경우 발주자가 국가인 경우에는 국가계약법을, 지방자치단체인 경우에는 지방계약법을 적용받게 되는데 이러한 산정기준의 문제점에 대해 명확하게 개선방안의 요구가 있음에도 개선방안이 제시되고 있지 않아 개별 문제점에 대한 면밀한 연구가 필요한 실정이다. 본 연구는 이러한 배경에서 '국가계약법'에 따른 산정기준과 '지방계약법'에 따른 산정기준의 각 산정결과를 비교하고, 문제점을 고찰 후 현장사례를 분석하여 적정한 기준을 제시하였다. 각 규정을 고찰한 결과 기타경비 산정방식이 다르게 규정되어 있었으며 이에 따라 실제 비용이 적게는 12.37%부터 24.95%까지 차이가 발생하고 있다는 결과를 얻을 수 있었다. 이러한 문제점은 실비가 아닌 계약당시 요율을 그대로 기타경비요율로 적용하는 국가계약법에 따른산정방식의 문제점에 따른 것이며, 이에 따라 실제 비용보다 적은 공기연장 비용이 산정되는 것으로 나타났다. 이에 본 연구는 현장자료를 기반으로 적정한 기타경비 산정요율을 총공사비 대비 1일당 기타경비 요율과 간접비 대비 요율방식으로 제시하였다.

• 한국건설관리학회논문집
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• 제12권1호
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• pp.53-61
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• 2011

건축 프로젝트는 그 다양성과 특수성으로 인해 많은 불확실성을 갖고 있다. 이러한 불확실성을 해소하기 위해 공사비 예측은 건축 프로젝트의 전 과정에 걸쳐 반복적으로 이루어져야 하며 특히 초기단계의 공사비 예측은 효과적인 사업 추진을 위해 매우 중요한 과정이다. 통상 초기단계 공사비 예측은 과거에 수행되었던 실적공사와의 비교를 기반으로 하며, 이러한 원리를 이용한 기계학습방법이 사례기반추론이다. 사례기반추론은 해결하고자 하는 문제와 유사한 사례를 데이터베이스에서 검색, 수정하여 해답을 얻는 방법으로 이를 위해서는 속성 유사도와 속성 가중치의 정의가 필요하다. 그러나 속성 가중치를 결정하는 문제에 있어서, 기존의 방법들은 정성변수의 속성 가중치 결정이 불가능하다는 단점이 있으며, 이는 사례기반추론에 사용할 수 있는 변수를 한정시키기 때문에 공사비 예측의 정확성을 저해시키는 요인이 되고 있다. 따라서 본 연구는 최적화 문제를 해결하는 기법의 하나인 유전 알고리즘을 이용하여 정성변수의 속성 가중치 결정 방법을 제안하고, 이를 국방 병영생활관과 공공아파트에 적용하여 그 유효성을 검증하였다.

• 기술혁신연구
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• 제7권1호
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• pp.151-175
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• 1999

This study develops principles for determining and managing costs applicable to grants and cooperative agreements for basic research. We investigated financial management policies of funding agencies and foundations in the United States, United Kingdom, Canada, Germany, Japan and Korea. Also we surveyed opinions of researchers and research fund administrators in Korean universities. Based on our review of funding agencies and our survey, the recommended management policies for grants and cooperative agreements are as follows: (1) Cost Structure. Cost of a sponsored agreement is comprised of the allowable direct costs and allocable portion of the allowable indirect costs. Direct costs can be further divided into salaries and wages, equipment, and other direct costs. (2) Salaries and Wages. Salaries and wages applied to a grant are paid for services rendered to the project during the period of performance of the particular agreement. In order to give researchers financial incentive, researcher allowance can be paid up to 30% of his/her regular salary. (3) Equipment. Any property purchased with grants which has an acquisition cost of 5,000,000 won or more per item and a normal life expectancy of two years or more is defined as equipment. Expenditures for special purpose equipment are allowable provided the acquisition of items is necessary for the research supported by the grant. (4) Other Direct Costs. Other direct costs are comprised of travel (both domestic and foreign), materials, other costs. Other costs may not exceed 30% of total other direct costs. (5) Indirect Costs. Since there is no clear consensus on indirect costs and additional budget is necessary to support actual indirect costs, the practical policy at the moment is to give a research support expense in lieu of indirect costs. In the future, however, some form of actual indirect costs should be supported. This study develops principles for determining and managing costs applicable to grants and cooperative agreements funded by the Ministry of Science and Technology. This research can be applied to other governmental agencies to give consistency and uniformity in administration of grants and cooperative agreements.

• 수산경영론집
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• 제8권2호
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• pp.1-19
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• 1977

The results analyzed of the actual state of medium size two-boat trawler fishery based on the cost expended in 1975 are as follows: According to the calculation of interest, the total cost of this fishery comes to ￦ 55,353,807, and in this account, the production cost comes to ￦ 49,747,383 (89.9%) and the material cost comes to ￦ 27,027,662(48.8%), the labour cost comes to ￦ 10,381,013 (18.8%) the expenses, ￦12,338,708(22.3%) and commision and interest comes to ￦ 5,606,424 (10.1%). As above the fishery comes is 90% of production cost for the expense of production. The ratio of cost element to the total cost 100 is as follow: Fuel: 23.6%, allocation: 14.3%, fishing gear: 14.1%, boat repair: 13.0%, fish box: 8.5%, ice: 14.1%, commission: 6.9%, food cost: 4.5%, interest: 3.2%, transportation fee: 2.8%, consumption: 2.6%, tax: 2.5%, depreciation: 2.4%, administrative expense: 1.6%. The unit cost of catches to each box, including the interest, cames to ￦ 2,167 and not calculating the interest it comes to ￦ 2,098. The cost production to each kg comes to ￦ 114 including interest, without interest, it comes ￦110. When the production cost comes to 90.6%, it comes to 9.4% of total revenue. The reason which this fishery brings low income is that the boats are almost old and semi-diesel engine is used. So, fuel expense and repaire expenses needs too much. Acconding to above this fishery needs to replace new boat and new engine. And new are for this fishery needs to bring under cultivation in order to bring good income with the new method for this fishery. Specially, this fishery brings low income from July to September because of its rest from labour. And so, the expenses, item, and account of money, and the trust money the cost element are not showed in August.

• 보건행정학회지
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• 제23권4호
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• pp.343-348
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• 2013

Background: Price control alone may not successfully restrain growth in health expenditures. This study aimed to propose fee adjustment model suitable for Korea reflecting health service volume and to clarify applicability of the model by comparing actual conversion factor with estimated conversion factor from simulation of this model. Methods: Fee adjustment model was developed based on Alberta's fee adjustment formula in Canada and 7 alternatives were assessed according to diversely applied parameters of the model. Results: Estimated conversion factors of the tertiary care hospital and the hospital were lower than actual conversion factors, since the utilization of heath service has been increased. However, there was no big difference between estimated conversion factors and actual conversion factors of the general hospital and the clinic. Eventually this fee adjustment model could estimate proper conversion factor reflecting health service volume. Conclusion: This model may be applicable to the mechanism as determining conversion factor between insurer and provider via negotiation and controling growth in health expenditures.

• 전력전자학회논문지
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• 제24권2호
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• pp.99-104
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• 2019

Solar power generation systems require maximum power point tracking (MPPT) control to acquire maximum power using inefficient and high-cost PV modules. Most conventional MPPT algorithms are based on the slope-tracking concept. The perturb and observe (P&O) algorithm is a typical slope-tracking method. The two factors that determine the MPPT performance of P&O algorithm are the MPPT control period and the magnitude of the perturbation voltage. The MPPT controller quickly moves to the new maximum power point at insolation change when the perturbation voltage is set to large, and the error of output power will be huge in the steady state even when insolation is not changing. The dynamics of the MPPT controller can be accelerated even though the perturbation voltage is set to small when the MPPT control period is set to short. However, too short MPPT control period does not improve MPPT performance but consumes the MPPT controller resources. Therefore, analyzing the performance of the MPPT controller is necessary for actual insolation conditions in real weather environment to determine the optimum MPPT control period and the magnitude of the perturbation voltage. This study proposes an optimum MPPT control period that maximizes MPPT efficiency by measuring and analyzing actual insolation profiles in typical clear and cloudy weather in central Korea.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2006년도 정기학술발표대회 논문집
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• pp.289-294
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• 2006

한국의 건설 산업에서 주거부분은 많은 부분을 차지하고 있다. 그리고 2005년 기성실적보고 자료를 봤을 때 주거부분에서의 대부분은 공동주택이다. 이 점에서 공동주택 건설 공사의 예산을 효율적으로 관리하고, 공동주택 건설의 물가동향을 정확히 파악하기 위해서 공동주택 건설 공사비 지수를 개발하는 것은 중요한 과제이다. 이런 이유로 건설기술연구원에서 연 2회 공동주택 건설 공사비 지수가 발행되고 있지만 더욱 발전되고 있지 못하고 있는 상황이다. 그러므로 본 논문은 공동주택 건설 공사의 특성을 반영하기 위하여 통계적 방법으로 대표 공동주택 건설 공사의 내역서를 이용하여 투입 구성비를 직접 조사하는 방법을 사용하여 보다 정확한 지수를 개발하고자 한다.