• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.966-970
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• 2007

하천정비기본계획에는 하천 등급별로 빈도 홍수량과 빈도 홍수위가 제시되어 있다. 홍수위 산정에는 조도계수가 영향을 미치므로 모든 하천정비기본계획에는 하천 구간별 조도계수가 산정, 제시되어 있다. 그런데 하천의 이용은 시대에 따라 변화되고 있으며 최근 환경적 기능이 강조되고 있어 하천 내의 수목에 대한 관점 또한 과거 치수 목적이 위주가 되었던 시대와는 달라졌다. 그러므로 이제는 홍수터를 포함하는 하천 부지내에서 자생 혹은 식재한 수목에 대한 고려가 필요한 상황이다. 수목 생장은 조도계수를 변화시키므로 이를 고려하기 위해서는 다시 조도에 대한 고려한 필요한 상황이다. 이러한 배경에서 본 조사는 국내의 다양한 하천에 대해 기존에 수립된 하천정비기본계획을 토대로 조도계수의 범위와 특성 및 그 산정 방법을 분석하는데 목적을 두었다. 하천정비기본계획 분석 결과, 조도계수는 하천 규모와 관계없이 주로 $0.025{\sim}0.040$ 범위에 있으며, 대체로 과업 구간이 5개의 이하로 분할되어 적용되었다. 산정 방법은 주로 하상재료 및 하도 형태에 대한 현장 판단과 기수립된 하천정비기본계획의 참고, 과거 흔적수위를 기초로 부등류 모형을 적용하는 등이었다. 본 조사의 결과로 현재 조도계수 산정의 문제점이 분석되었으며 향후 조도계수 산정의 개선 방향이 제시되었다.

• Journal of Korea Water Resources Association
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• v.36 no.4
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• pp.547-559
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• 2003

In this study, a mathematical model is developed for sewer rehabilitation planning by considering cost and inflow/infiltration. A sewer rehabilitation planning model is required to decide the economic life of the sewer by considering trade-off between cost and inflow/infiltration. And it is required to find the optimal rehabilitation timing, according to the cost effectiveness of each sewer rehabilitation within the budget. To solve the problem, we formulated a multiple objective mixed integer programming(MOMIP) model based on network flow optimization. The network is composed of state nodes and arcs. The state nodes represent the remaining life and the arcs represent the change of the state. The model considers multiple objectives which are cost minimization and minimization of inflow/infiltration. Using the multiple objective optimization, the trade-off between the cost and inflow/infiltration is presented to the planner so that a proper sewer rehabilitation plan can be selected.

• Journal of the Korea Society of Computer and Information
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• v.26 no.12
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• pp.255-264
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• 2021

In this paper, we propose operations and maintenance (O&M) planning approach for floating offshore wind farm using the mathematical optimization. To be specific, we present a MILP (Mixed Integer Linear Programming that suggests the composition of vessels, technicians, and maintenance works on a weekly basis. We reflect accessibility to wind turbines based on weather data and loss of power generation using the Jensen wake model to identify downtime cost that vary from time to time. This paper also includes a description of two-stage approach for maintenance planning & detailed scheduling and numeric analysis of the number of vessels and technicians on the O&M cost. Finally, the MILP model could be utilized in order to establish the suitable and effective maintenance planning reflecting domestic situation.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.596-598
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• 2003

본 논문에서는 CBP 가격을 기반으로, TWBP시장의 가격을 분석하였다. KPX가 발표한 SMP와 수요예측자료로 누적입찰자료를 추정하었으며, 이를 이용하여 계획예방정비에 따른 TWBP가격 변동을 시뮬레이션 하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.5
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• pp.465-469
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• 2010

Air heater used in power plant helps increase the thermal efficiency of the boiler by recovering the heat from the boiler flue gas and thus preventing the loss of useful heat. This study investigates the effect of preventive maintenance on the performance of the air heater in a power plant. Performance indexes for the air heater are calculated to observe the changes in the performance and operation status of the air heater before and after preventive maintenance. The major performance indexes considered are temperature efficiency of the flue gas side, air leakage rate, heat recovery rate, heat transmission rate, and heat capacity ratio. The performance of the air heater is evaluated before and after preventive maintenance; our results show that all the abovementioned performance indexes are improved after the maintenance.

• Nuclear industry
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• v.21 no.7 s.221
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• pp.25-29
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• 2001

• Journal of Korean Society of Transportation
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• v.19 no.6
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• pp.49-63
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• 2001

The pattern of urban transport activity has two major components: the movement of people and the movement of goods. Roads in urban areas carry large number of trucks laden with goods that support urban economy and lifestyle. Therefore urban goods movement plays a vital role, but at the same time, urban goods movement are an important source of congestion, and a major contributor to the adverse environmental and social impacts of urban transport. In addition, the demand for goods movement is growing at a faster rate than personal travel in many cities, due to changes in industry logistics and consumer purchasing patterns. As a result, the significance of urban freight activity is increasing in terms of both its role in urban economy and its adverse impacts on urban amenity. This study is focused on the role and involvement scope of metropolitan government in urban logistics aimed at increasing its efficiency and reducing its negative impacts. The major suggestions of this study are (a) development of a measure of urban goods movement activity, (b) evaluation of data requirements and availability, (c) dialogue between the public sector and private sector, and (d) the role of metropolitan government.

• Journal of Aerospace System Engineering
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• v.17 no.5
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• pp.1-10
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• 2023

This research sought to determine the optimal cycle of Planned Depot Maintenance (PDM) for Unmanned Aerial Vehicle (UAV), and PDM through Reliability and Maintainability-based simulation and Operating and Support (O&S) cost analysis using Reliability and Maintainability analysis results. The effectiveness of the PDM was verified economically, and the optimal PDM interval that balances UAV effective operations and sustaining engineering costs was presented.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.1585-1588
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• 2008

조도계수를 산정하는데는 수많은 방법이 있다. 그러나 일반적으로 하천정비기본계획(또는 댐실시설계보고서 등 각종보고서)의 조도계수를 그대로 적용하거나, 기준이 모호한 조도계수정보테이블(Roughness Coefficients Information Table)을 이용하고 있다. 하천의 이용은 시대에 따라 달라지며 최근 하천정비 사업의 급속한 진행으로 하천정비기본계획의 조도계수 또한 하천형상을 정확히 반영하기 어려운 현실이다. 소하천의 경우 하천정비기본계획 마저 수립되어 있지 않은 경우도 있어 조도계수로 인한 하천모의에 영향은 매우 크다. 따라서 소하천의 정확한 모의를 위해서는 소하천에 적합한 조도계수 산정방법에 대한 비교분석이 선행되어야 한다. 그러므로 본 연구에서는 실제 소하천에서 획득한 실측자료로부터 다양한 조도계수 산정방법을 적용하여 그 결과를 비교 분석하였다.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.3
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• pp.233-240
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• 2000

A small rivers take advantage of not only a site of superb scenic beauty, a play space, a rest place but also a momentous waters reservoir, a drainage on territory residents. Likewise, part of the most massed a life space to a region dwellers shall be extremely in harmony with coexistence space in that every kind plant, animal over again a human being and so on. For improvement planning of small river, various way and model are presented. But, it's want of ability for small rivers of a adaption many-side and throwing in a lot of financial resources. Because the improvement planning of small river was designed all small river in a county, the priority must be preprocessed. Now, the counties prioritized for improvement planning of small river are a few, and acquisition and manipulation of the data are time-consuming. Geo-Spatial Information System (GSIS) is specifically designed to manage and analyze spatial data. It will be to offer the benefit to the determination of the improvement priority in a small river. The purpose of this study is to offer priority for improvement planning of small river using GSIS. For this purpose, it was developed using Arc/Info software and AML was used as a developing tool.