• Journal of the Korean Society of Industry Convergence
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• v.26 no.6_2
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• pp.1097-1108
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• 2023

Recently, demand for technology for energy economy and stable supply is increasing due to the increase in power demand of loads. The amount of DC power generation using new and renewable energy is noticeably increasing, and the use of DC power supplies is also increasing due to the increase in electric vehicles and digital loads. During parallel operation to increase the capacity of the power converter, the module bus method or the method using Can communication and serial communication has significant difficulties in smooth operation due to communication time delay for information sharing. Synchronization of information sharing of each power converter is essential for smooth parallel operation, and minimization of communication time delay is urgently needed as a way to overcome this problem. In this paper, a new communication method using pulse width information is proposed as a communication method specialized for parallel operation of power converters to compensate for the disadvantage of communication transmission delay in the existing system. The proposed communication method has the advantage of being easily implemented using the PWM and Capture function of the microcomputer. In addition, the DC/DC converter for DC distribution was verified through simulation and experiment, and it has the advantage of easy capacity expansion when applied to parallel operation of various types of power converters as well as DC/DC converters.

• Fire Science and Engineering
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• v.34 no.4
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• pp.107-114
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• 2020

With the development of the national industry, the importance of the elderly and children such as the elderly, disabled, and children is recognized. Similarly, the number of facilities for the elderly and children is increasing. Fires at facilities for the elderly and children cause heavy casualties. In response to these events, it is essential to activate fire alarms promptly and accurately and to secure evacuation routes. In this study, the laws and statistics related to facilities for elderly and children were reviewed, and problems with legal terms-such as elderly, children, others, unwanted alarm of fire alarm systems, blind spots of fire compartment standards, securing evacuation routes, and absence of standards for life safety rescue organizations-were identified. As an improvement measure, the legal definitions of similar terms-such as elderly, children, unwanted alarm checklist, and establishment of standards for fire prevention compartment-and introduction of other terms-evacuation elevators, the establishment of standards for life-safety rescue organizations, and provision of flame retardation objects for evacuees-were proposed.

• Journal of Distribution Science
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• v.6 no.2
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• pp.5-19
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• 2008

This study aims to provide the present general state of basic data about refrigeration and freezing warehouses scold storages because basic data about refrigeration and freezing warehouses are insufficient and imperfect at the moment. Research contents include the present general state of cold storages such as sales amount, capital(money invested), storage possession state by type, keeping area, cold storage facility capacity, and facility state such as existence of rack, building structure and floor height, and possessed facility state. According to research results, it was found that 86.7% of refrigeration and freezing warehouses are located in the capital region and Busan region in terms of regional distribution, and the average keeping area was found to be bigger in these two regions than that of other regions. In addition, the research shows that more than 80% of companies possess bonded warehouses and there was no big difference in the size and capacity of refrigeration and freezing warehouses. Regarding building structure, most of them were found to be reinforced concrete. However, only 25% of companies installed racks, but there was no statistical significance between existence of rack and the amount of capital and sales. Possessed facilities were found in the order of freight elevator, information system and dock. When it comes to cargo gear, companies were found to possess 9.1 units of forklift and 2.2 units of reach stacker in average. This research is expected to lay a basis for investigating, predicting and developing the local cold storage industry, and more detailed studies will be needed in the future.