• Current Photovoltaic Research
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• v.9 no.2
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• pp.59-73
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• 2021

The purpose of this study is to develop a business model that efficiently converts diesel power generation systems to renewable energy microgrids (MG) in large-scale islands. Most of the previous studies on the conversion of renewable energy MG in islands had limitations dealing with efficiency from the perspective of suppliers. However, the microgrid has the characteristic of getting benefits through the interaction between the consumer and the supplier. In addition, the efficient MG business model from the perspective of new institutional economics is a structure in which consumers and suppliers jointly participate. Therefore, this study assumed that the MG business model in which the supplier's MG and the consumer's community solar participated would benefit all participants, and verified the assumptions using domestic island data. In terms of supplier investment, the cost of power supply (LCOE) of assumed model was calculated to be 14.0% lower than that of the diesel model and 3.7% lower than that of the supplier-only MG model. From the perspective of consumer investment, electricity bills are expected to be reduced by more than 200,000 won per household per year through self-generation of solar power. Social benefits are expected to reduce external environmental costs. The CO₂ emissions of the assumed model were calculated to be 39.5% lower than the diesel model and 1.5% lower than the supplier-only MG model. Therefore, the MG business model with consumer participation proposed in this study is expected to be an efficient alternative to renewable energy MG conversion in domestic islands, and is meaningful as an energy plan that improves the benefits of local residents.

• Journal of Korean Society of Rural Planning
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• v.27 no.1
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• pp.9-20
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• 2021

In order to develop practical indicator that can diagnose the regional conditions and characteristics of fishing villages, this study reviewed domestic and foreign researches and selected the diagnostic indicator of fishing villages by spatial unit. The major categories are divided into population and society, economic conditions, and living conditions. The middle categories consists of population, household, industry, tourism, settlement, environment, safety, health and welfare, education, and culture and leisure. The indicator were selected with reference to the existence of statistical data officially provided according to the spatial range(Si/Gun, eup/myeon, village). Based on the selected indicator, the test evaluation was conducted in Jindo-gun, Jeollanam-do by applying data that can be obtained from KOSIS and web GIS. It is judged that the diagnostic indicator developed through this research can be used in various ways from the planning stage to the implementation stage of the regional development project, such as grasping the current conditions, setting improvement targets, promotion and evaluation/monitoring of the project. In addition, it is expected that it will be possible to carry out regional diagnosis for each spatial unit and to plan and implement regional development projects by giving priority to areas where the level of each department is insufficient.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.11
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• pp.612-620
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• 2017

Power consumption in Southeast Asia is steadily increasing due to industrialization and the effects of hot and humid climates. However, there are not enough energy generation facilities and infrastructures to meet the growing demand because it is difficult to secure the construction and operation costs of the transmission and distribution systems. This study aims to develop a gas engine driven heat pump system that supplies heating, cooling and electric power to buildings. This system, besides its normal function to produce heat, has the capacity to generate electricity on a household level. This paper investigates similar cases overseas before developing the system. Through the investigation of commercialized similar systems, the level of technology and market trend of development system were identified. Features and specifications of commercial and industrial systems will be used for system development.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.2
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• pp.1-10
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• 2017

The high costs of electric vehicle supply equipment (EVSE) and installation are currently a stumbling block to the proliferation of electric vehicles (EVs). The cost-effective solutions are needed to support the expansion of charging infrastructure. In this paper, we develope EV charging system based on the big data analysis of the power consumption patterns. The developed EV charging system is consisted of the smart EV outlet, gateways, powergates, the big data management system, and mobile applications. The smart EV outlet is designed to low costs of equipment and installation by replacing the existing 220V outlet. We can connect the smart EV outlet to household appliances. Z-wave technology is used in the smart EV outlet to provide the EV power usage to users using Apps. The smart EV outlet provides 220V EV charging and therefore, we can restore vehicle driving range during overnight and work hours.

• Journal of Environmental Science International
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• v.16 no.2
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• pp.227-232
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• 2007

Water pollution in enclosed water bodies such as lake and river has become a serious problem over the world. Domestic wastewater is responsible for more than 60 % pollution load in public water area in Korea. Effluent of the treated domestic wastewater at low removal level is abundantly fed rivers and lakes and thus be an serious cause of lake pollution. Therefore, effective implement of domestic wastewater treatment in basin of lake and river must be prepared. The septic tank is one of the effective domestic wastewater treatment equipment and used in individual treatment for a unit of household, The purpose of septic tank as biological treatment system is simultaneously to remove BOD, T-N, T-P and reduce turbidity from influent. Accordingly, the appropriate control of functional microorganisms is important subject for the establishment of stability and economy of the biological treatment method. Especially, microanimals as a high-ranked microorganisms of food-chain are important, because microanimals control the other microorganisms especially various bacteria and effect on function of treatment. Therefore, it is necessary that functional predator like rotifers are attached in wastewater treatment process. In this study, the methods for attachment high density the rotifer to and improvement of transparency in the effluence by a dense rotifer was examined using laboratory scale biological treatment reactor simulated septic tank and real one.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.1078-1087
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• 2003

Kimchi refrigerator is a household electric appliance developed with the wholly domestic technology for maturing and keeping kimchi. However, the principle of keeping is not yet revealed obviously. This numerical study has been conducted to investigate the flow and heat transfer characteristics in a kimchi refrigerator. The effects of arrangement variation of a evaporation tube are examined. Also, the heat transfer characteristics through the insulation material are discussed in detail. The flow and temperature field was simulated using the commercial code of CFX-5.3. A natural convection flow is formed through about 5/6 region from the bottom within the keeping space and accordingly, the 90% region of kimchi containers satisfies the temperature requirement with 0$\pm$0.5$^{\circ}C$. The stagnant flow exists in the upper 1/6 region of the keeping space and accordingly, the stratified high temperature distributions appear in the upper region of kimchi containers. The upward shift of the start location of a evaporation tube improves the temperature concentration toward $0^{\circ}C$ but the pitch variation is of no effect. The heat fluxes on the insulation surfaces show two-dimensional distributions with being higher toward the center. Through the variation of insulation thickness, 3.5% saving of insulation material is obtained under the same heat transfer rate.

• Korean Journal of Organic Agriculture
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• v.26 no.3
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• pp.327-349
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• 2018

The purpose of the study focuses on the agriculture education services in the changing rural areas conditions such as population decline, aging society, and returning farmers. The study reviews the effects of agricultural education services on returning farmers and local residents for satisfaction, intention for recommendation, and intention to continue participation. Further, the study aims to investigate any difference in the level of satisfaction for two groups. The results suggested that there is a meaningful difference between return-farmers and local residents. Among the demographic variables, age and income showed a notable difference. However, sex, level of education and type of household did not suggest noticeable differences. In addition, the study accessed agricultural education from a service perspective and analyzed its service quality and customer satisfaction, loyalty and relationship using a service profit chain model. Like the result of most other studies, the analysis showed that these had positive relationships. While the study focused on the efficiency of agriculture education training program in agriculture technology centers, the study carries a meaningful value in that it discovered a meaningful difference in the satisfaction level between returning farmers and locals despite the fact that agriculture education was applied as a part of service. In practical terms, the study pointed out the need for consumer-centered education that reflects the characteristics of the groups rather than standardized education.

• The Korean Journal of Emergency Medical Services
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• v.7 no.1
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• pp.119-126
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• 2003

The results of analyzing the questionnaires with 119 emergency staffs working in Gwangju and Jeonnam region are as follows. 1. The whole stress score was mean 2.94 and the degree of stress from personal relationship was highest as 3.22. 2. There were significant differences in possession of qualification related to public health and medical treatment (F=3.090, p=.030) in service factors, total career of emergency staffs (F=2.979, p=.023) in working environment factors, age (F=2.835, p=.042) and sex (F=2.375, p=.019) in social position factors, possession of medical qualification (F=3.995, p=.010) and household account burden (F=2.777, p=.045) in personal relationship factors. 3. There were correlations (p=.475) between working environment factors and social position (p<0.01) and correlations (p=.508) between working environment factors and personal relationship factors (p<0.01). There was correlation (p=.415) between social position and personal relationship factors(p<0.01). More concrete research that examines whether current fire station operation system is desirable or not by comparing the degree of stress of the whole 119 emergency staffs in Korea is needed and it is considered that real allowance level should be secured to reduce their stresses and facility and guarantee system to satisfy their demands for welfare are required.

• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2138-2145
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• 2017

A hybrid system combining renewable technologies with diesel generators is a promising solution for rural electrification. Myanmar has many renewable energy resources, and many regions that cannot be supplied with electricity from the main grid. Therefore, in this study, we select a village in Myanmar, which is located far away from the substation, and evaluate the economic feasibility of a hybrid system for the village considering the specific local conditions and resource availability. We consider a hybrid system composed of a photovoltaic source, diesel generator, battery energy storage system, and converter. The load profiles of the household data from the village, and the solar radiation profiles are determined. The advantages of the hybrid system, in terms of cost, reliability, and environmental effects are analyzed through simulations using commercial software. The simulation results show that, for the selected village in Myanmar, a hybrid system with battery energy storage can reduce the cost and greenhouse gas emissions while maintaining reliability. We also obtain an optimized design in terms of the component size for the selected hybrid system with battery energy storage.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1916-1924
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• 2017

Fossil oil, as the main energy of transportation, is destined to be exhausted. The electrification of transportation is a sustainable solution to the energy crisis, since electric power could be acquired from the inexhaustible sun, wind and water. Among all the problems that hinder the development of Electric Vehicle (EV) industry, charging issue might be the most prominent one. In this paper, the service process of a charging station with Battery Energy Storage System (BESS) is analyzed by means of $Cram{\acute{e}}r$ - Lundberg model which has been intensively utilized in ruin theory. The service quality is proposed in two dimensions: the service efficiency and the service reliability. The arrival rate and State of Charge (SOC) upon arrival are derived from 2009 National Household Travel Survey (NHTS). The simulations are performed to show how the service quality is determined by the system parameters such as the number of servers, the service rate, the initial capacity, the charge rate and the maximum waiting time. At last, the economic analysis of the system is conducted and the best combination of the system parameters are given.