• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.244-245
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• 2010

Hybrid distribution system is able to use existing AC load under AC power and DC power by providing existing AC power and proper DC voltage at the same time. and, the future expected DC appliance is also available. Hybrid distribution system is divided into two different type. the one is DC common method and the other is AC common method. This paper design each system, and study operating characteristics for improving energy efficiency.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.427-429
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• 2003

The reliability performance of distribution networks will be enhanced with the installation of application programs including feeder reconfiguration program for loss minimization and optimization of system capacity. Although the basic functions of remote monitoring and remote control provide no measurable cost benefit the suite of application programs developed and now being commissioned by KEPCO, the future will continue to offer this utility with substantial savings in system operational costs, improve system reliability and customer service.

• Journal of Power System Engineering
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• v.14 no.6
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• pp.61-66
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• 2010

Engineering asset management (EAM) requires the accurate assessment of current and the prediction of future asset health condition. Suitable mathematical models that are capable of predicting time-to-failure and the probability of failure in future time are essential. In general reliability models, lifetime of component and system is estimated using failure time data. This paper deals with the reliability assessment of elevators using life of main components. Especially this work is concerned with the stochastic nature of life of elevator components. First, we investigate the Weibull statistical analysis of lifetime data for the components. The final goal is to establish the mathematical model for reliability assessment. This work provides more perspectives to future research in the fields of reliability and maintainability.

• East Asian Journal of Business Economics (EAJBE)
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• v.8 no.4
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• pp.19-28
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• 2020

Purpose - This study aims to lay the foundation for a desirable direction to solve future environmental problems through framework research on environmental cooperation according to distribution of urbanization between South and North Korea. The article also attempts to explore solution to two Koreas' environmental problems from the cooperative perspective between South and North Korea and draw future policy tasks. Research design, data, and methodology - For methodology, North Korea's legal system to cope with disasters is taken into consideration in terms of literature review. This study also analyzes a series of processes related to North Korea's disaster management through case study, and draws policy measures for North and South Korea's cooperation scope and methods. Result - The results support that North Korea is very vulnerable to environmental disasters due to food shortages, economic sanctions, and enormous natural disaster damages including flood damages occurring each year, because of the lack of disaster prevention infrastructure such as river maintenance. Conclusion - At the current time when North and South Koran exchange and cooperation increase, a disaster management cooperative system is needed for the areas where South and North Korea manage through division. It also suggests that there is a need to establish regulations and procedures for support items in advance for a quick response to disasters in North Korean region.

• Journal of Korean Society on Water Environment
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• v.23 no.3
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• pp.356-366
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• 2007

In this paper a methodology is developed to prioritize replacement of water distribution pipes according to the economical efficiency of replacement and assess the long-term effects of water main replacement policies on water distribution systems. The methodology is implemented with MATLAB to develop a computer algorithm which is used to apply the methodology to a case study water distribution system. A pipe break prediction model is used to estimate future costs of pipe repair and replacement, and the economically optimal replacement time of a pipe is estimated by obtaining the time at which the present worth of the total costs of repair and replacement is minimum. The equation for estimating the present worth of the total cost is modified to reflect the fact that a pipe can be replaced in between of failure events. The results of the analyses show that about 9.5% of the pipes in the case study system is required to be replaced within the planning horizon. Analyses of the yearly pipe replacement requirements for the case study system are provided along with the compositions of the replacement. The effects of water main replacement policies, for which yearly replacement length scenario and yearly replacement budget scenario are used, during a planning horizon are simulated in terms of the predicted number of pipe failures and the saved repair costs.

• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.179-188
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• 2020

The influx of marine exotic and alien species is disrupting marine ecosystems and aquaculture. Herdmania momus, reported as an invasive species, is distributed all along the coast of Jeju Island and has been confirmed to be distributed and spread to Busan. The potential habitats and distribution of H. momus were estimated using the maximum entropy (MaxEnt) model, quantum geographic information system (QGIS), and Bio-ocean rasters for analysis of climate and environment(Bio-ORACLE), which can predict the distribution and spread based only on species occurrence data using species distribution model (SDM). Temperature and salinity were selected as environmental variables based on previous literature. Additionally, two different representative concentration pathway (RCP) scenarios (RCP 4.5 and RCP 8.5) were set up to estimate future and potential habitats owing to climate change. The prediction of potential habitats and distribution for H. momus using MaxEnt confirmed maximum temperature as the highest contributor(77.1%), and mean salinity, the lowest (0%). And the potential habitats and distribution of H. momus were the highest on Jeju Island, and no potential habitat or distribution was seen in the Yellow Sea. Different RCP scenarios showed that at RCP 4.5, H. momus would be distributed along the coast of Jeju Island in the year 2050 and that the distribution would expand to parts of the Korea Strait by the year 2100. RCP 8.5, the distribution in 2050 is predicted to be similar to that at RCP 4.5; however, by 2100, the distribution is predicted to expand to parts of the Korea Strait and the East Sea. This study can be utilized as basic data to effectively control the ecological injuries by H. momus by predicting its spread and distribution both at present and in the future.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.3
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• pp.152-160
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• 2004

A novel UPQC(Unified Power Quality Conditioner), which consists of series inverter, shunt inverter, distributed generation system, is proposed. The proposing system can compensate reactive power, harmonics, voltage sag and swell, voltage interruption etc. through the change of paralleling operation mode and islanding operation mode. The control strategy for the proposing system was derived using the instantaneous power method. The performance of proposing system was analyzed by means of the PSCAD/EMTDC simulation and the experimental work with the hardware prototype. The proposing system has the ultimate capability of improving power quality at the point of installation on power distribution systems or Industrial power systems and can be utilized for the custom power device in th future distribution system.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.251-255
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• 2003

This paper proposes a novel UPQC(unified power quality conditioner) based on H-bridge modules, isolated through single-phase multi-winding transformers. The dynamic performance of proposed system was analyzed by simulation with EMTDC/PSCAD, assuming that the UPQC is connected with the 22.9kV distribution line. The proposed system can be directly connected to the transmission line without series injection transformers. It has flexibility in expanding the operation voltage by increasing the number of H-bridge modules and can compensate reactive power, harmonics, voltage sag and swell, voltage unbalance. The control strategy for the proposing UPQC was derived using the instantaneous power method. The proposing UPQC has the ultimate capability of improving power quality at the point of installation on power distribution systems and can be utilized for the future distribution system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.13 no.6
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• pp.523-529
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• 2020

Power distribution management system is essential for the efficient management and operation of power distribution networks. The power distribution system is a system that manages the distribution network based on IT, and has been evolving along with the development of the power industry. The current power distribution system is designed to operate at a relatively low network transmission speed based on the independent operation of the main equipment. However, due to distributed resources such as photovoltaic or energy storage devices, which are rapidly increasing in popularity in recent years, the operation of future distribution environments is becoming more complex, and various information needs to be collected in real time. In this study, the requirements of the next-generation power distribution system were derived to overcome the limitations of the existing power distribution system, and based on this, the communication network system and performance requirements for the distribution system were defined. In order to verify the performance of the designed system, a software-based terminal device simulator was developed because it takes excessive time and cost to introduce a large-scale system such as a power distribution system. Using the simulator, a test environment similar to the actual operation was established, and the number of terminal devices was increased up to 1,000. The proposed system was shown to satisfy the requirements to support the functions of the next-generation power distribution system, recording less than 10 % of the communication network bandwidth.

• Journal of the Korean Society of Clothing and Textiles
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• v.17 no.2
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• pp.265-279
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• 1993

The channel of distribution exists for the purpose of moving product from the manufactuerer to the final consumer. In order to satisfy consumer needs, channels provide for the those products to arrive at the right place, at the right time and in the quantity, quality and price desired. Currently, there has been an emerging interest in the improvement of distribution system in many areas of industries and Korean government because of a market liberalizatiion begun at 1989 and still has processed step by step. In the wave of market liberalization, an understanding of the channel of distribution and structure would be very crucial when developing the opportunities of competitive advantages in Korean apparel industry. The purposes of this study were to investigate the determinants of the distribution channel and to identify how to respond to the market liberalization for developing the possible future strategies in the apparel industry. Data for this study were obtained from interviews with managers in apparel company in addition to a questionnaire mailed to over 106 middle management position of apparel company. Data were analyzed by using descriptive statistics. The results of this study were summarized as follows. 1. In the distribution channel of the apparel industry, a vertical marketing system, comprising producer, apparel company, retailer, prevailed without intermediaries such as wholesalers or vendors. Especially, the apparel company controlled marketing channel members. This type of system may reflect added product cost and may be not advantageous to retailers and consumers because most apparel companies are responsible for its own transfortation, storage and stocks after season. 2. In the view of market liberalization, most apparrel companies showed double-edged viewpoints. In terms of positive aspect, it would give stimulus to broaden variety of fashion merchandise and to improve product quality of fashion merchanise which were the most disadvantageous factors in competing with oversea's brands. In terms of negative aspect, it would bring the bankruptcy of small or medium sized apparel firms and the foreign products' penetration in domestic market. From this study, severel recommedations were suggested forward to improve the present condition in apparel industry. They included eliminating the power of apparel company and reinforcing middlemen for more efficient distribution system and for satisfying consumer needs in rapidly changing environment. Also it included government supports, reinforcement of information system, improvement in channel structure, and career development program in conjunction with apparel companies and academic society for improving scientific management and future potential strategies in Korean apparal industry.