• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.7
• /
• pp.1287-1293
• /
• 2009

This paper presents an application of Harmony Search (HM) meta-heuristic optimization algorithm for optimal operation of microgrid system. The microgrid system considered in this paper consists of a wind turbine, a diesel generator, and a fuel cell. An one day load profile which divided 20 minute data and wind resource for wind turbine generator were used for the study. In optimization, the HS algorithm is used for solving the problem of microgrid system operation which a various generation resources are available to meet the customer load demand with minimum operating cost. The application of HS algorithm to optimal operation of microgrid proves its effectiveness to determine optimally the generating resources without any differences of load mismatch and having its nature of fast convergency time as compared to other optimization method.

• Journal of the Korean Society of Systems Engineering
• /
• v.13 no.1
• /
• pp.79-88
• /
• 2017

For the PBL contract, it is necessary for the contracting parties to share information regarding the reasonable inventory-level and the cost of its repair parts for the estimated demand. There are various models which can be used for this purpose. Among them, V-METRIC model is considered to be the most efficient and is most frequently applied. However, this model is usually used for optimizing the inventory level of the repair parts of the system under operation. The model uses a time series forecast model to determine the demand rate, which is a mandatory input factor for the model, based on past field data. However, since the system at the deployment stage has no operational performance record, it is necessary to find another alternative to be used as the demand rate of the model application. This research applies the V-METRIC model to find the optimal inventory level and cost estimation for repairable items to meet the target operational availability, which is a key performance indicator, at the time of the PBL contract for the deployment system. This study uses the calculated value based on the allocated MTBF to the system as the demand rate, which is used as input data for the model. Also, we would like to examine changes in inventory level and cost according to the changes in target operational availability and MTBF allocation.

• Journal of the Korean Society for Railway
• /
• v.14 no.6
• /
• pp.575-583
• /
• 2011

In order to minimize the maintenance cost at local lines, Information & Communication Technology based onboard train control system is being developed. Unlike the central traffic control based fixed block system, this system use a moving block method and railway driver direct control switch and railway crossing. The purpose of this paper is to analyze the concerned main operational issues are as follows: the preparation of train operation, drivability, the role of driver and controller, block system and cost. We defined the role of driver and driver's input data for train service, and we designed the business process of driver using UML tool. We considered the aspect of drivability, DMI is needed to support the braking moment for the driver and driver training simulator. We designed the driver business process for control of switch and railway crossing. We analyzed the fixed block system and moving block system to confirm the difference with the existing operational method. The cost analysis structure is also needed for the operation cost comparison.

• IE interfaces
• /
• v.18 no.4
• /
• pp.418-430
• /
• 2005

We establish an efficient strategy for construction and operation of data consolidation center for multi-organization in public sector. First, we introduce important concepts on data consolidation center in public sector, and draw some success factors by analyzing several foreign and domestic cases. Second, we construct all the possible logical operational models of the center and investigate the properties and feasibility of the models. Third, we suggest a virtual operational environment for the two representative models selected by feasibility criteria among the possible logical models, and compare the two models in terms of operational cost. We also utilize AHP methodology to evaluate qualitative opinions on the two models from several experts in public information systems. As a result, we find the best alternative is the case in which all infrastructure and facilities for the center are provided by government, and common essential IT operations are integrated, associated data are consolidated and the whole operational work are outsourced to specialized IT operations service providers.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.27 no.2
• /
• pp.1-9
• /
• 2004

This study aims to examine the relationship between total quality management(TQM) practices and operational performance perceived by employees who are in different functional organization types, R&D function and Non-R&D function organization in manufacturing companies. Operational performance is defined as the degree of operation efficiency in the perspective of quality, delivery, and cost. Our study showed that the significant elements of TQM practice were different depending on functional organization types. In case of R&D organization, the categories of customer focus and process management were the strongest significant predictors of operational performance. Therefore, the optimal TQM practices for R&D organization can be obtained in consideration of customer focus and process management.

• International conference on construction engineering and project management
• /
• 2013.01a
• /
• pp.188-195
• /
• 2013

Construction operations generate a significant amount of air pollutant emissions, including carbon emissions. The environmental performance of construction operations is closely relevant to the operational efficiency of each resource employed, which indicates how efficiently each resource (e.g., construction equipment) is utilized. In this context, monitoring the operational efficiency of construction equipment provides key information in managing and improving the environmental performance and productivity of construction operations. In this paper, we report our efforts to measure the operational efficiency of construction equipment, using low-cost accelerometers. An experimental study and real-world case studies are conducted to demonstrate the feasibility of the proposed approach. The results have shown the potential of this approach as an economically feasible means of monitoring the environmental performance of construction operations.

• Journal of the Korean Dietetic Association
• /
• v.9 no.3
• /
• pp.197-208
• /
• 2003

This study was surveyed to provide the information on current operational practices and issues of contract-managed foodservice companies. Questionnaires were distributed to 79 contract-managed foodservice companies (eight large-size, 48 mid-size, 23 small-size companies) from March to May in 2002. The contract-managed foodservice companies provided averages of 269,184 (range 140,036-503,500), 14,837 (range 450-75,269), and 4,065 (range 930-8,050) meals daily from large, medium, and small-size companies, respectively. The companies managed to averages of 268.2 (160-619) foodservice contracts at large-size companies, 21.9 (5-63) contracts at mid-size companies, and 4.7 (1-10) contracts at small-size companies. The average numbers of dietitians were 298.6 (range 104-671) in large-size companies, 22.2(6-86) in mid-size companies, and 3.8(1-9) in small-size companies. The averages of sales were 156.5 billion at large-size companies, 6.7 billion at mid-size companies, and 1.7 billion at small-size companies in 2001. The contract was two types including management fee contract(5%), and profit and loss contract(95%). The cost ratios for office foodservice were 59.5% at food cost, 24.2% at labor cost, 6.3% at profit, and 10.1% at other cost. For hospital foodservice, the ratios were 54.0% at the food cost, 34.6% at labor cost, 3.0% at profit, and 11.8% at other cost. For high school foodservice, the ratios were 62.2% at the food cost, 21.5% at labor cost, 5.4% at profit, and 11.2% at other cost. When the contractors managed to the foodservice, the most important matters were the sanitation management and customer satisfaction. Also, the difficult problems were excess investment of equipments and low meal prices.

• Journal of the Korean Society of Food Culture
• /
• v.37 no.4
• /
• pp.335-344
• /
• 2022

The study was aimed to investigate the operational meal costs by kindergarten size in Seoul and to analyze recognition for optimal meal prices. A survey (31.6% recovery rate) was conducted on all kindergartens (779 kindergartens) in Seoul on April 2021 using descriptive analysis, t-test, and dispersion method. A price sensitivity measurement (psm) method was used to determine optimal meal prices. Result showed an average food cost for kindergartens of 2,647 won, an average labor cost of 605 won, an average operating cost of 146 won, and the total meal cost of 3,506 won. Total meal cost decreased with increasing kindergarten size (p<0.001). On the other hand, kindergartens with more students decreased the ratio of food cost to total meal cost, and operating cost and labor costs (p<0.001) increased. The optimal price of kindergarten operators' meal cost (OPP) was KRW 3,673. Furthermore, the analysis showed the sensitivity of operators' meal costs to kindergarten size was insignificant.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.1043-1048
• /
• 2011

In the case of a low density branch line, these areas are operating at a loss. So much money is used for infrastructure maintenance cost. To solve the problem, our institute have a project to develop the Information & Communication Technology based train operation system. In a similar research in the Europe, The UK's Transport Research Laboratory experienced analysis of operational issue for developing ERTMS from Level II to Level III. In this paper, we study about railway operational issues before development of ICT based train operation system. An analysis target of operational issues are railway business process & data, drivability and moving or virtual block system.

• Journal of Korean Society for Quality Management
• /
• v.33 no.4
• /
• pp.75-87
• /
• 2005

Generally speaking, weapon system is defined as a combination of primary system and support system which are evaluated by capability and operational availability respectively. Recently comparison of total life cycle cost shows that logistic support system is proved to be more important than primary system. However, until now systematic approach to support system development has not been applied in the area of developing support system. We need to construct a universal metric for effectiveness of logistic support system and to cut out whatever activities or support elements which do not contribute to the metric. This paper describes a new approach based on system engineering approach to logistic support system and also classifies five factors of failure, stock-out frequency, administrative delay time, active repair time and logistic delay time that have influence on operational availability of logistic support system.