• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.12
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• pp.1804-1809
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• 2015

The study in railway system to apply a fuel cell system with high efficiency and mobility than other renewable energy is being actively conducted. It is needed a analysis on load characteristics and control method of rolling stock in order to apply to rolling stock. This paper presents study on control small-scale prototype power converter electric railway vehicle using fuel cell generation system. Experiment is conducted through real fuel cell generation system and reference speed applying the driving curve of the actual electric railway vehicle was applied. Also, output voltage of boost converter is controlled considering characteristic of fuel cell. And it was confirmed characteristic according to powering and regeneration of inverter.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.4
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• pp.326-330
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• 2020

Small-scale production control systems for smart manufacturing are becoming increasingly necessary as the manufacturing industry seeks to maximize manufacturing efficiency as the demand for customized product production increases. Correspondingly, the development of an embedded system to realize this capability is becoming important. In this study, we developed an embedded system based on an open source system that is cheaper than a widely applied programmable logic controller (PLC)-based production control system that is easier to install, configure, and process than a conventional relay control panel. This embedded system is system is based on a low-power, high-performance Cortex M4 processor and can be applied to smart manufacturing. It is designed to improve the development environment and compatibility of existing PLCs, control small-scale production systems, and enable data collection through heterogeneous communication. The real-time response characteristics were confirmed through an operation test for input/output control and data collection, and it was confirmed that they can be used in industrial sites.

• Journal of Power System Engineering
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• v.13 no.6
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• pp.129-136
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• 2009

A motor cylinder is widely used as an apparatus for transportation of a small scale load. It is, however, difficult for only one motor cylinder to transfer a large scale load such as a weir. The large scale load is transferred by two motor cylinders which are mounted on right and left of load itself. In this case, the displacement difference generated between two motor cylinders, namely, the synchronous error has a bad influence on the transportation. In this study, a synchronous control system is designed to restrain synchronous error caused by skew disturbance. The control system is composed of two disturbance observers and one synchronous controller. Each disturbance observer is designed to restrain the skew disturbance. And the synchronous controller is designed to achieve stable and accurate synchronization. Finally, the simulation results show that the designed control system is effective for the skew disturbance which lead to synchronous error.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1592-1597
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• 2004

Experimental studies were carried out to confirm the turbulent enhancement of the cooling system of nuclear reactor by large scale vortex generation in nuclear fuel rod bundle. The large scale vortex motions were generated by rearranging the inclination angles of mixing vanes to the coordinate directions. Experimental studies were carried out at Reynolds Number 60,000 with hydraulic condition. Normal variations of mean velocity and turbulent intensity in the rod bundle subchannel were measured by the 2-color LDV measurement system. The turbulence generated by split mixing vanes has small length scales so that they maintain only about 10DH after the spacer grid. On the other hand, the turbulences generated by the large scale vortex continue more and remain up $25D_{H}$ after the spacer grid.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8509-8515
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• 2015

The aim of this study was to investigate the relationship between job stress and smoking behaviors among small scale manufacturing male workers. A self administered questionnaire was given to 856 male workers employed in 24 work places under 50 members of manufacturing industries. As a results, the smoking rates of small scale manufacturing male workers was 35.2%. In the results of multiple logistic regression analysis to know the relationship between job stress and smoking behaviors, the Odds ratio of the total score of Korean Occupational Stress Scale(KOSS) and its subarea(physical environment, job demand, organizational system, lack of reward and occupational climate) were significantly increased in high risk group than normal group. These results suggested that job stress may play a significant role in the smoking behaviors in the high risk group than normal group of small scale manufacturing male workers.

• International Journal of Human Ecology
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• v.2 no.1
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• pp.39-55
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• 2001

Concerns about paid-facilities for the elderly with dementia from middle and upper class families have been discussed lately in Korea. Small-scale, home-like group homes for the elderly with dementia were developed in Sweden in the 1980, but they have not been effectively introduced in Korea where they remain a comparatively new concept. The group home, however, would provide a good alternative to Koreans who feel guilty when they have to leave their frail parents in large-scale facilities or hospitals instead of caring for them at home. The aim of this paper is, first, to define the care of the demented elderly who come from upper and middle class families in Korea and, secondly, to discuss the need for group homes to help care for them. A survey was done by questionnaire and was answered by 577 respondents who belonged to middle and upper class families living in Korea in December 2000. Methods of analysis were frequency, mean, and Chi-square. The results of this study were as follows: 1) the traditional notion that the eldest son should be burdened with the primary responsibility for a demented parent has weakened remarkably; 2) a small-scale long-term care facility was considered the most desirable living environment for the demented elderly; 3) the facilities families needed for professional hospitals for victims of dementia, senior citizen centers, large and small-scale long-term care facilities, day-care centers, and short-stay and service housing. The study also revealed that there was low awareness of the group home. The most preferred type of structure for group homes was a single-family detached house, and the most preferred management system was small-scale that could create home-like atmosphere. Additionally the respondents wanted group homes to consist of 6-8 residents with 2-4 persons per room. The results of this study strongly suggest that policy makers should encourage the development of smallscale group homes as an alternative form of housing for the elderly with dementia.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.6
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• pp.460-466
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• 2009

The mixing method of water and chemicals is significant in a small-scale water supply system because drinking water should be supplied with a certain quantity of remaining chemicals maintained. In the present study, the concentration distribution and the mixing index were obtained from four models, which were to find out the optimal mixing method of water and chemicals. The two models brought the good mixing effects out of the four, one for providing chemicals from the center of water supply pipe and the other for setting up the semicircle block at the downstream of the chemicals-providing pipe. As a result, the mixing effect was found out to be increased due to the diffusion and the disturbance of flows. In conclusion, these numerical results are expected to contribute to designing the optimal mixing system.

• Journal of Distribution Science
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• v.19 no.1
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• pp.61-73
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• 2021

Purpose: The transition from a traditional to a modern food distribution system induces several adjustments on the supply side since supermarkets must collect food on a larger scale and with higher quality standards. This situation becomes a real challenge for small scale farmers to access supply in a modern distribution channel. This gives rise to an original solution: supplying supermarkets through farmer associations or cooperatives. Based on this context of Vietnam linking to the case of distribution science, the paper proposes an industrial organization model of the food processing system in developing countries. The model presents the competitive relationship between two competing distribution systems: a traditional and a modern one. The former is composed of several retailers that sell their products on the traditional market while the latter is based on cooperatives that collect food and negotiate with supermarkets. The current study is to discuss the conditions under which the evolution of the food distribution system occurs by using the proposed model. Research design, data, and methodology: Based on the proposed model, the study explored the quantity flow from small producers to consumers through a Nash equilibrium and address the question of farmer repartition by a free-entry equilibrium. Results: The result shows that there is a unique positive equilibrium in the food market with participation of cooperative associations; Since farmers serve cooperative associations, they not only receive quantity incentive prices but also share profits within their organization. Conclusions: This study shows a unique distribution equilibrium where the profits of farmers working for middlemen and cooperatives are maximized. Further insights were discussed.

• Journal of the Korea Safety Management & Science
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• v.20 no.2
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• pp.21-35
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• 2018

The purpose of this study is to reduce the accident rate by introducing a safety system for small construction sites belonging to local governments. In the case of a small construction site, permission is granted through the building permission department and the construction management of the building safety management of 1,000 square meters of floor area less than 3 stories is not properly performed in the Enforcement Decree of the Building Act of Korea. In the current state of industrial accidents in 2016, 81.8% of all accident victims are found to be vulnerable to accident such as those occurring at work places with less than 50 employees. Considering the fact that the construction work with less than 5 billion KRW of the construction cost in Korea generates the most deaths, it is time to introduce the safety and health system of local governments.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.643-651
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• 2008

This study was conducted to promote reliability of the simulated result for the long-term streamflow in Daecheong watershed. This system was constructed by the SSARR model that considered the effect of small scale irrigation facilities. We investigated the present condition of small scale irrigation facilities and analyzed the relation between irrigation facilities and river discharge. According to the analysis result about the effect of irrigation facilities, the error occurrence frequency was increased at the sub-basin that has many reservoirs and during the second quarter except for the 2003 year. Therefore, we created the relative equation between small irrigation facilities and river water and estimated the simulated streamflow for the main stations. Consequently, error of the runoff simulated with considering small scale irrigation facilities was decreased than that without considering small scale irrigation facilities at all.