• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.448-451
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• 1999

This paper describes controller development for a dynamic voltage compensator using a shunt diode converter and series inverter. The control system was designed using 1/4 period integrator and vector relationship between the supply voltage and load voltage. A simulation model and scaled hardware model were developed for analyzing performance of the controller and the whole system. Both results confirm that the dynamic compensator can restore the load voltage under the fault of the distribution system.

• IE interfaces
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• v.17 no.4
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• pp.472-481
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• 2004

In this paper, we propose a linear programming model of supply planning process for the supply chain collaboration strategy of a company. The amount of its supplying quantity relies on outsourcing suppliers heavily. Conversely, the revenues of those suppliers are highly dependent on the supplying quota from the supply network planning of the company. In order to keep the supply stable through collaboration, the company builds such a policy to guarantee the fairness on revenue between the supplies. For this, the supply network plan should keep the capacity utilization ratio even for all the suppliers. But the production capacities are different and the distribution of molds is disproportional through suppliers, so the supply network plan is not easily established with simple arithmetic processes. Therefore, we developed the linear programming model with those target function and constraints minimizing the costs for holding inventory and penalty of delayed delivery, simultaneously guaranteeing the even capacity utilization through suppliers. The proposed model has been applied to real case and the evaluation for the planning result from the model would be followed in order to make sure that our model guarantee on extracting the supply network plan subordinated to the policy. Also we mention about further studies for improvement of the model.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.1176-1181
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• 2006

The purpose of this study was to estimate water supply analysis and reliability indicators by using allocation rule(AR) about Andong Dam and Imha Dam which have parallel reservoirs system. According to the analysis results of allocation rule, for Rule(A) and Rule(B), the contribution of water supply in Andong Dam was 60% more than in Imha Dam, and for Rule(C), the contributions in Andong Dam and Imha Dam were almost equal. In Rule(C), supply is allocated by the ratio which divides the sum of storage and inflow by the mean storage according to the storage state and supply capability state of Andong Dam and Imha Dam. This Rule(C) showed good results in the water supply capability analysis and reliability analysis of parallel reservoirs. In the analysis criteria of water supply in parallel reservoirs system, monthly water change quantity showed better results than monthly constant water quantity in water supply analysis. On the basis of this study, the new technique for water supply analysis was developed to be applied to parallel reservoirs, and this operation rule will establish the efficient operation measures in the application to several kinds of parallel reservoirs system.

• Korean Journal of Construction Engineering and Management
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• v.12 no.5
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• pp.35-45
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• 2011

Establishing housing supply strategies in Korean housing market is a crucial issue due to contradictory but concurrent two problems in market; one is the unstable working-class residential and the other is the high vacancy rate by the low-level of sales rate. Although government has been continuously implementing various supply policies in an attempt to evenly distribute houses as well as to keep supply and demand in balance, it is difficult to satisfy all of stakeholders, such as housing consumers, housing owners and housing suppliers. This paper, therefore, applies a system dynamics methodology and offers a dynamic and integrated model encompassing for-profit behaviors of each market participants. The proposed model simulates the future trends of house prices, the balances between supply and demand, construction companies earnings and vacancy rate when applying various housing supply scenarios. From the simulation result, recent governmental small-size rental housing supplies in bulks should utilize private construction companies to stabilize housing distribution rate and private supply system as well as the supply and demand are well balanced.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.4
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• pp.112-119
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• 2017

Selecting suppliers in the global supply chain is the very difficult and complicated decision making problem particularly due to the various types of supply risk in addition to the uncertain performance of the potential suppliers. This paper proposes a multi-phase decision making model for supplier selection under supply risks in global supply chains. In the first phase, the model suggests supplier selection solutions suitable to a given condition of decision making using a rule-based expert system. The expert system consists of a knowledge base of supplier selection solutions and an "if-then" rule-based inference engine. The knowledge base contains information about options and their consistency for seven characteristics of 20 supplier selection solutions chosen from articles published in SCIE journals since 2010. In the second phase, the model computes the potential suppliers' general performance indices using a technique for order preference by similarity to ideal solution (TOPSIS) based on their scores obtained by applying the suggested solutions. In the third phase, the model computes their risk indices using a TOPSIS based on their historical and predicted scores obtained by applying a risk evaluation algorithm. The evaluation algorithm deals with seven types of supply risk that significantly affect supplier's performance and eventually influence buyer's production plan. In the fourth phase, the model selects Pareto optimal suppliers based on their general performance and risk indices. An example demonstrates the implementation of the proposed model. The proposed model provides supply chain managers with a practical tool to effectively select best suppliers while considering supply risks as well as the general performance.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.5
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• pp.311-321
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• 2020

In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.6
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• pp.396-402
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• 2009

Recently many efforts have been carried out on the development of energy-efficient and environment-friendly systems in order to preserve natural environment and to reduce environmental loads in the branch of the urban planning and the building design. In this study, a mathematical method was developed and a numerical analysis was carried out with various parameters to provide substantial data for optimal design and operation of urban energy supply systems. Components of the system and their specifications, such as a co-generation system and other heating and cooling systems, could be obtained through this analysis for various resource and energy requirements in urban area. In this study, the system constituents and operating characteristics, and their economic performances such as the value of objective function, the amount of energy consumption were discussed for various load patterns and power load ratios. Also, it turns out that the optimal energy supply system can save energy by $10{\sim}20%$ in comparison with the conventional energy supply system.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.63-70
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• 2010

A construction process of hydrogen peroxide supply system was investigated to use hydrogen peroxide as an oxidizer of bi-propellant liquid rocket engine. To use hydrogen peroxide as a rocket propellant, it has to be in high concentration over 90%. It is very important to make the supply system free of pollutants, because highly concentrated hydrogen peroxide has a characteristic of hypersensitive reaction to pollutants such as dust and oil sludge. We suggested the cleaning and passivation process of main components to minimize pollutants of the supply system. In conclusion, we verified stability of the constructed supply system by leak test and hot test.

• Journal of Sensor Science and Technology
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• v.24 no.5
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• pp.331-341
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• 2015

In this paper, real-time water quality monitoring system of small water supply facilities based on IEEE 802.15.4e-2012 DSME MAC and IEEE 802.15.4g-2012 PHY standard is presented, which is capable to acquire for highly reliable water quality information in the wide outdoor areas for effective water quality management of small water quality facilities is distributed in the long distance and remote areas. Previously, Long distance transmission is difficult in most water quality sensor module is using RS-485 protocol. But with this system, even in harsh outdoor environment, it is possible to establish a radio wave sensor in a wide area network, and not only water quality sensor shall be connected to the wireless system, but also wireless integrated management system shall provide more effective way of management of the numerous small water supply facilities spread throughout the community, so that the administrator can remotely monitor the data of water turbidity, pH, residual chlorine in the water-supply, water-level, and generate alarm to cope with risks. The management of small water facilities is done by residents will be very effective to notice water quality information of small water facilities to residents.

• Current Research on Agriculture and Life Sciences
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• v.31 no.2
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• pp.139-147
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• 2013

This study analyzed agricultural water distribution systems for the utilization of water demand-oriented water supply systems. Three major TM/TC(telemeter/telecontrol) districts of agricultural water management were selected for analyzing the characteristics of the water distribution systems. In addition, the characteristics of the water supply systems for general water supply zones based on irrigation facilities were also investigated, along with the case of special water management during the drought season. As a result, high annual and monthly variations were observed for the water supply facilities, including the reservoirs and pumping stations. In particular, these variations were more obvious during the drought season, depending on the type of facility. The operations of the pumping stations and weirs were more sensitive to the stream levels than the reservoirs, and the smaller reservoirs were influenced more than the larger reservoirs. Therefore, a water-demand-oriented water supply system should consider the existing general practices of water management in the agricultural sector, and focus on achieving a laborsaving system rather than water conservation in the case of reservoirs. Equal water distribution from the start to the end point of irrigation channels could be an effective solution for managing pumping stations.