• Transactions on Electrical and Electronic Materials
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• v.7 no.5
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• pp.217-223
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• 2006

When only partial information is available about equipment failures (installation date and amount, as well as failure and replacement rates), data on sufficiently large number of yearly populations of the components can be combined, and estimation of model parameters may be possible. The parametric models may then be used for forecasting of the system's short term future failure and for formulation of replacement strategies. We employ the Weibull distribution and show how we estimate its parameters from past failure data. Using Monte Carlo simulations, it is possible to assess confidence ranges of the forecasted component performance data.

• Environmental and Resource Economics Review
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• v.11 no.3
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• pp.447-463
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• 2002

The heat demand prediction is an essential issue in management of district heating system. Without an accurate prediction through the lead-time period, it might be impossible to make a rational decision on many issues such as heat production scheduling and heat exchange among the plants which are very critical for the district heating company. The heat demand varies with the temperature as well as the time nonlinearly. And the parametric specification of the heat demand model would cause a misspecification bias in prediction. A nonparametric model for the short-term heat demand prediction has been developed as an alternative to avoiding the misspecification error and tested with the actual data. The prediction errors are reasonably small enough to use the model to predict a few hour ahead heat demand.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.E
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• pp.72-78
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• 1995

To support some knowledge in planning irrigation system, short or long-term irrigation scheduling or determining irrigation reservoir capacity, it is necessary to estimate peak irrigation requirements and seasonal distribution of water demands for various return periods. In this paper Dry Day Index and Probable Evapotranspiration were evaluated to decide seasonal consumptive use of paddy rice for a design year using several decades' daily rainfall data and 5 years'('82~'86) actual evapotranspiration data, respectively. To obtain Dry Day Index that is defined as the number of probable dry days for a given period, Slade unsymmetrical distribution function was adopted. Dry Day Index was analysed for 5 and 10-day intervals. Each of them was evaluated with return periods of 1, 3, 5, 10 and 20 year. Their singnificance was tested by X$^2$ method. Based on these values, the Probable Evaportanspiration, that is the average daily ET both in dry days and rainy days during a given period, was estimated. Crop coefficient was also determined by the modified Penman equation proposed by Doorenbos & Pruitt.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.194-195
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• 2006

미래의 전력 시스템은 환경과 기술적인 이유로 인해 더욱더 많은 분산전원을 이용하게 될 것이다. 분산전원은 서로 다른 특징을 가지고 있고 또한 배전계통에서 기존의 계통운영과는 다른 형태로 운전될 것이다. 이런 관점에서 다수의 분산전원을 모아 하나의 가상의 발전소로 운영하는 개념이 등장하게 되었는데, 이를 Virtual Power Plant(VPP)라고 한다. VPP는 매니지먼트 시스템이 관리하는 여러 클러스터들로 이루어져 있으며 이들 클러스터들은 각각 여러 종류의 분산전원으로 구성되어 있다. 본 논문에서는 클러스터를 이루는 분산전원을 어떻게 운영하는 것이 최적의 경제적 효율을 지닐 수 있을 지에 대해 논의하게 될 것이다. 디젤 발전기의 출력의 경우 그 소유자에 의해 제어가 가능하지만, 태양광 발전 시스템의 경우 기상 상태에 따라 그 출력이 결정된다. 따라서 이러한 각각의 특성을 고려하여 본 논문에서는 디젤, CHP(Combined Heat and Power), 보일러, 태양광발전으로 구성된 복합 시스템에서 각 시간별로 수용가의 전력 및 열 수요와 분산전원의 에너지 생산을 비교하여 VPP 최적 운영 계획을 구성하였다.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.410-411
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• 2006

This paper is focused on the survey on the power system modeling using a clustering algorithm. In electricity markets, clustering method is a efficient tool to model the power system. It can be seen that electricity markets can also be classified into several groups which show similar patterns and that the fundamental characteristics of power systems can be widely applicable to other technical problems in power system such as generation scheduling, power flow analysis, short-term load forecasting, and so on. There are several researches on the power system modeling using a clustering algorithm. We specially surveyed their own clustering methods to model the power system.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.9
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• pp.727-735
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• 2003

The determination of completion time constitutes an important step in developing algorithms for short-term production scheduling. Existing completion time algorithms of multi-product batch processes often assume that intermediate storage tanks are always available when it is needed. In this paper, we consider a serial multi-product batch plants with ZW and NIS policy intermediate storge tank. We limit storage residence time and allocated products in the intermediate storage tank to minimize the quality change of the stored material as well as to reduce the clearing time during product change. A set of recurrence relations is suggested to calculate the completion times for the given batch sequence of products on all processing units. Also analytic solution for the suggested model is solved by a graphical method. The effectiveness of these results is proved by a few illustrative examples.

• 한국IT서비스학회:학술대회논문집
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• 2003.05a
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• pp.577-583
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• 2003

Due to the widespread availability of the internet, large-scale and dynamic distributed projects in industry are becoming popular. We present a distributed, collaborative, and adaptive control approach for decentralized multiple projects, which is one of representative project environments in modern e-enterprises. In this paper we deal with short term scheduling and rescheduling of resources, which are shared by multiple projects. We in specific, address the dynamic nature of the situation. We model this as a dynamic economy, where the multiple local markets are established and cleared over time trading resource time slots(goods). Local markets are modeled using a combinatorial auction mechanism. Due to the dynamic and distributed nature of economy, through our approach we can achieve higher levels of flexibility, scalability and adaptability.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1254-1254
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• 2022

The Multi-family Residential is one of the most famous building types for a rental property in the US. Often times it includes multiple residential buildings and some amenity facilities, including a clubhouse or leasing office, swimming pool, dog park, and garages. Since the building type is built for rental purposes, the construction planning is phased and it makes the project complicated. Detailed planning and execution are important for successful construction management. This paper provides some management practices that are applied to one of the multi-family residential construction projects in Phoenix, AZ. The Front End Planning (FEP) process performed by both owner and contractor is the first key to a successful construction project. Specifically, the early review of phased turnover strategy, grading, fire/Americans with Disabilities Act (ADA) compliance, and Mechanical/ Electricity/Plumbing/Technology (MEPT) will provide absolute benefit to the project. Second, using a scheduling method to control short-term schedules and long-term can provide the ability to manage the issues with agility. Third, material delivery and procurement dominate the both project schedule and cost. With this COVID-19 circumstance, it is hard to expect the material, equipment, and labor forces to be delivered on time with the contracted price. Managing floats are more than important to managing construction productivity. Risk management should work to share the risks fairly. Lastly, turnover is directly linked with the profit of the project for both owner and contractor. The communication between the owner and contractor to re-schedule the proper turnover schedule is important for the phased construction project.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.11
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• pp.1495-1504
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• 2013

Renewable energy integration and increased system complexities make system operator maintain supply and demand balance harder than before. To keep the grid frequency in a stable range, an appropriate spinning reserve margin should be procured with consideration of ever-changing system situation, such as demand, wind power output and generator failure. This paper propose a novel concept of dynamic reserve, which arrange different spinning reserve margin depending on time. To investigate the effectiveness of the proposed dynamic reserve, we developed a new short-term reliability criterion that estimates the probability of a spinning reserve shortage events, thus indicating grid frequency stability. Uncertainties of demand forecast error, wind generation forecast error and generator failure have been modeled in probabilistic terms, and the proposed spinning reserve has been applied to generation scheduling. This approach has been tested on the modified IEEE 118-bus system with a wind farm. The results show that the required spinning reserve margin changes depending on the system situation of demand, wind generation and generator failure. Moreover the proposed approach could be utilized even in case of system configuration change, such as wind generation extension.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.10
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• pp.1108-1120
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• 1990

The present study is to develop an intelligent control system for flexible manufacturing system, which is suitable for a variety of manufacturing types with smaller production rates. The controller is designed to integrate heuristic rules with optimization techniques for loading as well as flow rate of parts and ultimately meeting performance indices. The control function implemented by an optimization technique is to calculate short term production rates of parts. The heuristic control determined by production rules requires knowledge base to evaluate selected loading alternatives according to short term production rate and current process information, and also to determine final decision pertaining to loading. In this case, the knowledge base is constructed using the rules for evaluating alternatives, decision criteria, and flow control of parts in manufacturing system. The database is formulated by means of managing and updating current process information. A graphic system to monitor current status of the function and operation of manufacturing system is developed, and computer simulation is carried out to evaluate the performance of the proposed controller.