• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.971-976
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• 2004

The management of railroad structures is more difficult and complicate because there are many structures such as rail, bridge, tunnel, station, and so on. Therefore, LCC(Life Cycle Cost) analysis of railroad structures as public infrastructure must contain a maintenance cost as well as an initial cost in order to make a more effective management during the life cycle on the design phase. This paper presents a cost classification scheme considering user costs such as value of delayed time of passenger and freight. Also, in this study it is developed a probabilistic life cycle cost(PLCC) analysis model of railroad structures taking into account uncertainties and variations of input variables in order to analyze LCC. It may be stated that the model proposed in this study can greatly contribute to the making optimal decision, the estimate of the maintenance cost and the allocate of budget in the project of railroad structures.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.289-292
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• 2005

It is not feasible for agricultural facility managers to estimate how severe damages are and what are causes of them when agricultural hydraulic facilities get damaged for some reasons. Moreover, it is nearly impossible for agricultural facility managers to take immediate actions to repair and reinforce the damaged structures. Thus, there have been needs for well-established systems to help agricultural facility managers understand its severity and causes, and take proper actions to reduce speed of deterioration and to repair/reinforce them. Thus repairing and reinforcing systems of agricultural hydraulic structures based on agricultural facility management policies, developed in this study, can be efficiently used in field works to determine top priority location and the budget of repairing and reinforcing projects if detailed information of damages in concrete structures and damage types are well compiled and classified with standardized image data complemented.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.476-478
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• 2003

Capability of material fixation in forest was noticed since COP3, but now it was difficult to understand material fixation in wide area. In this study, we attempted to estimate and test the amount of carbon, nitrogen, and phosphorus fixed by forest from satellite images. First, we classified into tree species and estimated the number of trees in the forest by species, area, and digital numbers. We inspected to apply it in wide area. Next, we compared the amount of carbon, nitrogen, and phosphorus with NDVI and each band of satellite images.

• 한국신뢰성학회지:신뢰성응용연구
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• 제18권2호
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• pp.184-191
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• 2018

Purpose: The purpose of this study is to propose a method to calculate the optimal preventive maintenance cycle of radar used in the aviation weapon system of ROKAF. Methods: A hybrid model is used to estimate the optimal preventive maintenance cycle in a system that can perform condition based predictive maintenance (CBPM) through continuous diagnosis. The failure data of the radars operating in the military were used to calculate the reliability. Results: According to the research results, the reliability threshold of the radar began to decrease after 5 flights, and decreased rapidly after 12 flights. Since the second check, costs have continued to decline. Conclusion: A method is proposed to determine the cycle of optimal preventive maintenance of radar within operational budget through modeling results between reliability limit and cost for radar. The results can be used to determine the optimal preventive maintenance cycle and frequency of various avionics equipment.

• 대한설비공학회지:설비저널
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• 제13권1호
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• pp.48-63
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• 1984

Standard Building Operation Conditions(SBOC) is to describe typical conditions under which a building would operate during the coulee of a day In order to develop SBOC profiles for office building, we surveyed the operating conditions of randomly selected 20 existing office buildings in Seoul by means of enquetes, and made SBOC profiles. SBOC profiles consist of human occupancy profile, light ins usage profile, system schedule and domestic hot water profile etc. SBOC profiles will be used as input data of DOE-2 computer program to estimate DER(Design Energy Requirements) and to develop EBL (Energy Budget Level), SBOC profiles are not meant to be exact description of how a building will actually be used by its respective users. Rather they are intended to be reasonable typical project ions of how buildings might be used.

• 대한토목학회논문집
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• 제35권4호
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• pp.815-820
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• 2015

제주도의 효율적 수자원 관리 기반을 구축하기 위해서는 지표수의 유출 특성과 증발산량, 지하수 함양량, 지하수 유출량의 상호관계를 정확하게 제시할 필요가 있다. 이 중 식생에 의한 차단(interception)효과는 증발산량에 직결되는 영향 인자임에도 정량적 분석의 어려움 때문에 유역단위로 정량화된 사례는 드물다. Von Hoyningen-Huene (1981)이 엽면적지수와 차단저류량의 관계를 밝혔고, LAI는 차단, 증산의 핵심요소로 다양한 수문모형에 활용되고 있다. 본 연구에서는 Kozak et al. (2007)이 제시한 엽면적 지수(LAI: Leaf Area Index)에 따른 차단저류량의 관계식을 이용하여 한국형 유역수문모형 SWAT-K (Soil and Water Assessment Tool-Korea)내에 식생에 의한 차단량 산정모듈을 개선하였다. 제주도 천미천 유역을 대상으로 적용한 결과 천미천 유역의 차단증발량은 85~104mm로서 전체 증발산량(993~1062mm)의 약 8~11% 만큼 차지하는 것으로 분석되어 전체 물수지 성분에 영향인자로 고려되어야 할 것이다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.21-24
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• 2006

Processes controlling the interannual variation of mixed layer temperature (MLT) averaged over the NINO3 domain ($150-90^{\circ}W$, $5^{\circ}N-5^{\circ}S$) are studied using an ocean data assimilation product that covers the period of 1993 to 2003. Advective tendencies are estimated here as the temperature fluxes through the domain's boundaries, with the boundary temperature referenced to the domain-averaged temperature to remove the dependence on temperature scale. The overall balance is such that surface heat flux opposes the MLT change but horizontal advection and subsurface processes assist the change. The zonal advective tendency is caused primarily by large-scale advection of warm-pool water through the western boundary of the domain. The meridional advective tendency is contributed mostly by Ekman current advecting large-scale temperature anomalies though the southern boundary of the domain. Unlike many previous studies, we explicitly evaluate the subsurface processes that consist of vertical mixing and entrainment. In particular, a rigorous method to estimate entrainment allows an exact budget closure. The vertical mixing across the mixed layer (ML) base has a contribution in phase with the MLT change. The entrainment tendency due to temporal change in ML depth is negligible comparing to other subsurface processes. The entrainment tendency by vertical advection across the ML base is dominated by large-scale changes in wind-driven upwelling and temperature of upwelling water. Tropical instability waves (TIWs) result in smaller-scale vertical advection that warms the domain during La Ni? cooling events. When the advective tendencies are evaluated by spatially averaging the conventional local advective tendencies of temperature, the apparent effects of currents with spatial scales smaller than the domain (such as TIWs) become very important as they redistribute heat within the NINO3 domain. However, such internal redistribution of heat does not represent external processes that control the domain-averaged MLT.

• 산업경영시스템학회지
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• 제40권1호
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• pp.95-104
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• 2017

This paper deals with solution methods for discrete and multi-valued optimization problems. The objective function of the problem incorporates noise effects generated in case that fitness evaluation is accomplished by computer based experiments such as Monte Carlo simulation or discrete event simulation. Meta heuristics including Genetic Algorithm (GA) and Discrete Particle Swarm Optimization (DPSO) can be used to solve these simulation based multi-valued optimization problems. In applying these population based meta heuristics to simulation based optimization problem, samples size to estimate the expected fitness value of a solution and population (particle) size in a generation (step) should be carefully determined to obtain reliable solutions. Under realistic environment with restriction on available computation time, there exists trade-off between these values. In this paper, the effects of sample and population sizes are analyzed under well-known multi-modal and multi-dimensional test functions with randomly generated noise effects. From the experimental results, it is shown that the performance of DPSO is superior to that of GA. While appropriate determination of population sizes is more important than sample size in GA, appropriate determination of sample size is more important than particle size in DPSO. Especially in DPSO, the solution quality under increasing sample sizes with steps is inferior to constant or decreasing sample sizes with steps. Furthermore, the performance of DPSO is improved when OCBA (Optimal Computing Budget Allocation) is incorporated in selecting the best particle in each step. In applying OCBA in DPSO, smaller value of incremental sample size is preferred to obtain better solutions.

• 한국항공우주학회지
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• 제39권6호
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• pp.576-584
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• 2011

성공적인 발사체 개발을 위해서는 개발비용을 정확하게 추정하는 것도 중요하지만 연차별 예산 배분을 적절히 계획하는 것도 중요하다. 본 논문에서는 통계적 기법을 이용하여 개발기간 중 연차별 예산 배분에 대하여 분석하였다. 연차별 비용 모델링을 위해서 통계적 모델의 분석을 통해 적합성을 판단하여 베타분포모델을 선택하였고, 프로젝트의 설계와 기술의 성숙도로 추정이 가능한 모델을 개발하였다. 연차별 비용 모델의 타당성을 검증하기 위하여 우주왕복선 주 엔진(Space Shuttle Main Engine)의 실제 개발비용 분포와 본 모델을 통한 개발비용 분포의 비교 연구를 통해 적합성을 확인하였다. 또한, 본 논문의 개발 비용 모델을 한국형발사체 개발에 적용하여 연차별 소요 비용을 추정하였다. 본 논문에서 제시하는 연차별 분포 모델은 발사체뿐만 아니라 다른 대형복합시스템의 개발에도 활용이 가능할 것으로 예상된다.

• 한국컴퓨터정보학회논문지
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• 제18권1호
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• pp.157-166
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• 2013

본 연구는 지방자치단체의 재정관리의 투명성에 대해 살펴보고 복식주의 발생주의 회계를 통해 이를 효과적이고 효율적으로 활용하여 재정 개혁의 기반을 다지기 위한 관리 방안을 모색하고자 한다. 주요한 내용을 정리하면 첫째, 정부회계기준의 지속적 개선의 필요, 둘째, 회계과목의 설정과 프로그램 예산과목과 연계 필요, 셋째, 정부사업에 투입된 자원의 총비용을 객관적으로 산정하기 위한 원가회계시스템의 구축 필요, 넷째, 공무원의 인식변화와 현재 순환보직 인사제도의 문제점 개선 및 교육훈련을 통한 회계공무원의 전문성 확보, 다섯째, 고위층의 관심과 공직 윤리시스템 강화, 여섯째, 내부 통제와 감시제도의 강화 필요, 일곱째, 독립된 외부전문가의 회계감사 실시와 회계전문가집단의 역할 필요, 마지막으로 효율적이고 실용적인 전산시스템 구축과 연구개발(R&D)사업이 지속적으로 실행되어야 할 것이다.