• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.643-645
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• 2003

In competitive electricity markets, each GenCo establishes generator maintenance schedule and submits to ISO those. Then, ISO reviews and arranges maintenance schedule of each GenCo to meet the standard for reliability. This paper presents the new optimization model which can apply to competitive electricity markets. The object of this model is to minimize schedules variation of each GenCo and to satisfy system reliability.

• 한국자동차공학회논문집
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• 제13권5호
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• pp.7-18
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• 2005

Over the past twenty years, the maintenance system has been developed and its importance has been increased. For the effective maintenance of the urban transit, we have developed the maintenance system based on the concept of RCM(Reliability Centered Maintenance). RCM analysis is a systematic approach to developing a cost-effective maintenance strategy based on the various components's reliability of the system in question. It is performed according to process that includes the following steps; definition of function and functional failures of the systems, construction of RB D(Reliability Block Diagram), performance of FMEA(Failure Modes & Effects Analysis) and calculation of the reliability index. The final process of RCM is to determine appropriate failure maintenance strategies. This paper aims to define the procedure of maintenace based on the concept of RCM for urban transit. The key for a successful maintenance system is an automated scheduling to the maximum extent possible and timely executions. The developed system issues maintenance plan and repair request based on analyzed data and maintenance experience.

• 한국통신학회논문지
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• 제32권1B호
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• pp.22-30
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• 2007

본 논문에서는 분산 객체 관리의 편의성을 제공하고, 고장 발생시에도 안정된 서비스를 가능케 하는 고장포용 객체그룹(Fault-Tolerant Object Group, FTOG) 프레임워크를 제안한다. FTOG 프레임워크는 서비스 우선순위와 체크포인트 방법을 이용하여 두 가지의 고장 회복 방안을 제공하며 퍼지 기반의 부하 추론 과정을 통한 부하 분산을 수행하여 서비스 실행에서의 효율성을 높인다. 또한 가상의 홈네트워크 환경을 구성하고 FTOG 프레임워크를 적용하여 시뮬레이션을 통해 분산되어 있는 객체들의 관리 및 부하 분산 등 본 모델의 안정성 및 신뢰성을 검증하였다.

• 한국정보통신학회논문지
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• 제13권4호
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• pp.720-726
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• 2009

대규모 데이터베이스 시스템에는 다양한 종류의 데이터들이 공존하고 있으며, 사용자에게 정확하고 유용한 정보를 제공하기 위해 데이터의 신선도를 유지하는 문제는 중요한 이슈로 등장하고 있다. 대부분의 이런 문제의 해결책은 적절한 시간내에 요청된 갱신질의어를 얼마나 효율적으로 수행하는가 하는 것이 관건이다. 본 논문에서는 데이터의 신선도 유지와 기아상태의 공정성을 유지하기 위한 갱신 스케줄링 알고리즘을 제안한다. 제안된 알고리즘은 요청된 갱신질의어 실행시간 할당을 위해 목표 갱신 비율을 일정한 스케줄링 주기마다 재 계산한다. 본 논문에서 제안된 알고리즘을 사용함에 따라 데이터들의 공정성과 신선도를 유지 할 수 있다. 동적, 반-동적, 정적 데이터의 갱신처리 결과를 보여주기 위해 통합 웹사이트를 구현하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권6호
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• pp.2060-2073
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• 2022

Cloud Computing permits users to access vast amounts of services of computing power in a virtualized environment. Providing secure services is essential. There are several problems to real-world optimization that are dynamic which means they tend to change over time. For these types of issues, the goal is not always to identify one optimum but to keep continuously adapting to the solution according to the change in the environment. The problem of scheduling in Cloud where new tasks keep coming over time is unique in terms of dynamic optimization problems. Until now, there has been a large majority of research made on the application of various Evolutionary Algorithms (EAs) to address the issues of dynamic optimization, with the focus on the maintenance of population diversity to ensure the flexibility for adapting to the changes in the environment. Generally, trust refers to the confidence or assurance in a set of entities that assure the security of data. In this work, a dynamic optimization technique is proposed to find an optimal trust weights in cloud during scheduling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 추계학술대회 논문집 전력기술부문
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• pp.30-32
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• 2006

New building, reinforcement, maintenance and test of power equipments are always necessary in a power system. Our power system is getting old and the total power capacity is also getting large, so power equipment outages are getting often. Power euipment outages make less margine for a stable condition of a power system operation. Therefore, through overviews and countermeasures against the outage should be made in order to be in a stable operational conditions during the outage. We have too many outages over 300 per month in our power system. So, we can't have enough time to study our power system and to make countermeasures without a helping program. This program is designed to give various and appropriate informations necessary for an outage scheduling. By applying this program, we can raise the job efficiency high and spare the time spent. So we can afford to do through system studies and make good countermeasures. I think this program can contribute greately to power system stable operation.

• Journal of Construction Engineering and Project Management
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• 제3권2호
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• pp.21-34
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• 2013

Various risk factors affect construction projects. Due to the uncertainties created by risk factors, actual activity durations frequently deviate from the estimated durations in either favorable or adverse direction. For this reason, evaluation of schedule uncertainty is required to make decisions accurately when managing construction projects. In this regard, this paper presents a new computer simulation model - the Repetitive Schedule Risk Analysis Model (RSRAM) - to evaluate unit-based repetitive building project schedules under uncertainty when activity durations and risk factors are correlated. The proposed model utilizes Monte Carlo Simulation and a Critical Path Method based repetitive scheduling procedure. This new procedure concurrently provides the utilization of resources without interruption and the maintenance of network logic through successive units. Furthermore, it enables assigning variable production rates to the activities from one unit to another and any kind of relationship type with or without lag time. Details of the model are described and an example application is presented. The findings show that the model produces realistic results regarding the extent of uncertainty inherent in the schedule.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 추계학술대회 논문집 전력기술부문
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• pp.429-431
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• 2001

The vertically integrated power industry was divided into six generation companies and one market operator, where electricity trading was launched at power exchange. In this environment, the profits of each generation companies are guaranteed according to utilization of their own generation equipments. This paper represents on generator maintenance scheduling and efficient bidding strategies for generation equipments through the calculation of the contract and the application of each generator cost function based on the past demand forecasting error and market operating data.

• 한국농공학회지
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• 제40권6호
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• pp.37-45
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• 1998

A survey was conducted to get information on the utilization of irrigation systems for greenhoyses farming. Three regions were selected which represent geographical chatacteristics such as neighboring urban area, flat-field area, and mountainous area. The number of greenhouses farms interviewed was 432 in total. The contents of the survey consisted of general characteristics of greenhouse farmers, the size and location of greenhouses, cultuvated crops, irrigation method, irrigation scheduling, and irrigation automation. The analysis of the surveyed data showed that greenhouse farmers did not take technical assistances. Proper criteria or guidelines for selection and operation of irrigation systems were not available. Irrigation systems were operated by hand. Irrigation scheduling were executed by farmer's experience. Maintenance of irrigation systems in general were poor. Development of economically reasonable irrigation system is of importance.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 춘계학술대회 논문집
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• pp.280-285
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• 2003

The process of railway traffic planning is composed of several steps such as long-term, mid-term. short-term, and real-time plan. The planning of vehicle and manpower resources is a main research topic in tactical short-term planning step. Railway vehicle is usually consisted of a power car, passenger/freight cars and human resource is composed of engine driver, cabin crew, ground personnel. So far, power car was main research target in railway vehicle scheduling problem. Recently according as the light electric railway or high-speed railway is introduced, the operational planning of trainset vehicles become important, In this paper, we introduce the conceptional model for trainset restoring problem and developed heuristic algorithm.