• Journal of the Economic Geographical Society of Korea
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• v.14 no.2
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• pp.157-175
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• 2011

This paper aims to analyze the characteristics of healthcare REITs' performance and operation, and to examine their use for activating the silver industries in Korea. The results of this study are as follows. First, according to the results of analyzing healthcare REITs' performance, healthcare REITs outperformed average REITs and extended investment proportion compared to total REITs after 2007. This outperforming came from not only rapid growth of silver industries, but also REITs strategy using the structure of sale-and-leaseback and triple-net lease. Second, healthcare REITs use selection and concentration strategy in terms of asset sector, but use portfolio diversification strategy in terms of investment region. Third, according to the analysis results, healthcare REITs are to be useful for activating the silver industries in Korea. In this context, major implications are presented to use healthcare REITs effectively.

• Journal of Power Electronics
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• v.18 no.5
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• pp.1595-1607
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• 2018

In this paper, a hierarchical control strategy is introduced to control a new three-port multidirectional DC-DC converter for integrating an energy storage system (ESS) to a bipolar DC microgrid (BPDCMG). The proposed converter provides a voltage-balancing function for the BPDCMG and adjusts the states of charge (SoC) of the ESS. Previous studies tend to balance the voltage of the BPDCMG buses with active sources or by transferring power from one bus to another. Furthermore, the batteries available in BPDCMGs were charged equally by both buses. However, this power sharing method does not guarantee efficient operation of the whole system. In order to achieve a higher efficiency and lower energy losses, a triple-layer hierarchical control strategy, including a primary droop controller, a secondary voltage restoration controller and a tertiary optimization controller are proposed. Thanks to the multi-functional operation of the proposed converter, its conversion stages are reduced. Furthermore, the efficiency and weight of the system are both improved. Therefore, this converter has a significant capability to be used in portable BPDCMGs such as electric DC ships. The converter modes are analyzed and small-signal models of the converter are extracted. Comprehensive simulation studies are carried out and a BPDCMG laboratory setup is implemented in order to validate the effectiveness of the proposed converter and its hierarchical control strategy. Simulation and experimental results show that using the proposed converter mitigates voltage imbalances. As a result, the system efficiency is improved by using the hierarchical optimal power flow control.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.181-186
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• 2013

In recent years, eco-friendliness and high fuel economy have become important issues for commercial tractors. Electric tractors are often required for operation in a greenhouse. However, the battery capacity limits the available operation time. To overcome this problem, a plug-in hybrid electric tractor is considered a reasonable alternative. This tractor has a basic driving ability and can operate in various working modes such as mower, rotary, loader, and trailing. This study focuses on the energy management strategy by considering various working modes.

• Strategy21
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• s.44
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• pp.291-322
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• 2018

This research aims to cast light upon security characteristics of the Peace Line, which have been underestimated. To understand maritime order and maritime security policy of the Republic of Korea between 1950 and 1970, it is necessary to analyze the Peace Line as line of defence and to investigate its character This research begins with analyzation of historical facts and investigation on security characteristics of the Peace Line. It goes further to examination of legal justification of the Peace Line, which was one of international legal issues of the period, principally regarding its security characteristics. As results of the study, it could be said that the security characteristics of the Peace Line was the line of defensive waters, which set its goal mainly to prevent infiltration of communist spies. The Peace Line had practical effect as it functioned as a base line of the ROK Navy to take anti-spy operation. At the early phase of the Korea-Japan Negotiation, the Korea delegation interpreted significance of the Peace Line passively. After abrogation of Clark Line, the delegation, however, became positive to maintain the Peace Line and its security characteristics. Security characteristics of the Peace Line was recognized again, as it became the base line of special maritime zone which was made in 1972. Through analysis on international law, it is concluded that the Peace Line was fair as a part of the right of self-defense against indirect aggression. North Korea attempted indirect aggression mainly from sea way, and these might undermine peace and cause urgent and unjust damage on the ROK. Thus the ROK's action of anti-spy operation through the Peace Line can be justifiable as considering the right of self-defence. Also the Peace Line accorded with principles of necessity, immediacy and proportionality. As it was argued on the above, the Peace Line as line of defence was one of the most significant factor in the ROK's maritime security history from the Hot war against communist forces to Cold war period after Korean War and must not be underestimated.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.243-248
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• 2006

Recently, China opened Yangshan port and provides a variety of benefits for shipping companies. Japan plans to reduce logistics costs and improve efficiency through the established 'super major ports' project. According to the 'hub and spokes' system, the number of direct calls toward North-Chinese ports are increasing. This changing environment has negative effects on the amount of transshipment cargos in Korean ports. In order to make a hub port of a domestic port, it is necessary to develop northeast Asian Feeder networks. Therefore, this paper analyzes the structure of northeast Asian feeder networks through the case study of European feeder networks strategy. Finally, we suggests the plans to reinforce feeder networks, which are strategic terminal operation, strategic alliances between shipping companies and port co-operation, for win-win strategy in the competitive northeast Asian market.

• Journal of the Korean Society of Safety
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• v.35 no.5
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• pp.121-127
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• 2020

Since the Fukushima nuclear accident in 2011, the public were concerned about the safety of Nuclear Power Plants (NPPs) in extreme natural disaster situations, such as earthquakes, flooding, heavy rain and tsunami, have been increasing around the world. Accordingly, the Stress Test was conducted in Europe, Japan, Russia, and other countries by reassessing the safety and response capabilities of NPPs in extreme natural disaster situations that exceed the design basis. The extreme natural disaster can put the NPPs in beyond-design-basis conditions such as the loss of the power system and the ultimate heat sink. The behaviors and capabilities of NPPs with losing their essential safety functions should be measured to find and supplement weak areas in hardware, procedures and coping strategies. The Loss of Ultimate Heat Sink (LUHS) accident assumes impairment of the essential service water system accompanying the failure of the component cooling water system. In such conditions, residual heat removal and cooling of safety-relevant components are not possible for a long period of time. It is therefore very important to establish coping strategies considering all available equipment to mitigate the consequence of the LUHS accident and keep the NPPs safe. In this study, thermal hydraulic behavior of the LUHS event was analyzed using RELAP5/Mod3.3 code. We also performed the sensitivity analysis to identify the effects of the operator recovery actions and operation strategy for charging pumps on the results of the LUHS accident.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.867-878
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• 2021

Recently, there has been active research on smart street lamps that can collect real-time traffic data and provide traffic information by attaching images and radars to road lighting facilities. Smart street light technology can detect, identify, and provide dense information compared to existing technologies. In order to effectively utilize the smart streetlight as a high-resolution information delivery medium, a branch-type operation strategy that is different from the existing centralized operation strategy is required. This study presents dynamic information delivery strategies, release strategies, and their criteria for various purposes in a spatial range, separated by the context before and after the occurrence of smart street lights-based accidents. Through this, it is expected that smart road lighting facilities can be used more effectively.

• Journal of Space Technology and Applications
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• v.1 no.2
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• pp.256-267
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• 2021

In this paper, the New Space characteristics and response of micro & small satellite, and space industrialization strategy using domestic technologies are described. Recently, micro & small satellites are developed worldwide, including Starlink, having the characteristics of low-cost, light-weight and satellite constellation. Therefore, it is necessary to prepare for the constellation operation by considering the use of Commercial Off-The-Shelf (COTS) parts, satellite weight, shape and mass production. In particular, it is necessary to develop Multi Input Multi Output (MIMO) technology in consideration of the frequency interference during constellation operation, and to prepare and make efforts to secure frequencies in the government. Among the commercial-grade memories of Samsung Electronics and SK Hynix, the space-grade memory field using radiation tolerant memory and the high reliable packaging and space environment test technology has potential as a space industrialization strategy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.5
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• pp.659-669
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• 2022

Recently, parking problems have repeatedly occurred not only in the residential areas of the old town, but in detached residential areas, neighborhood living facilities, and commercial areas of the planned New Town. This study suggests a strategy to minimize parking problems before constructing a New Town by reviewing these parking problems at the new city district planning stage. Parking problems can be divided into supply-demand and non-supply-based, and the solution strategy is reviewed in terms of supply and operation. The procedure for applying the solution strategy is proposed according to the effectiveness and ease of application.First, this paper suggests the PAZ (Parking Analysis Zone) as the basic analysis unit. Second, the supply-based parking problem in the concerned area based on the land use plan of Hanam Gyosan is reviewed. Last, solutions to a parking problem for each PAZ are presented.

• Journal of the Korean Society for information Management
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• v.26 no.3
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• pp.295-316
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• 2009

This research applied the concepts of IT architecture and IT governance for managing with an integrated computing environment and organized structure, which base a digital library's management and operation. It also aims to analyze the structural system between information technology of human resources and strategy alignment elements of business, which both constitute the core content. Social network analysis software was used to investigate the complicated relationship between IT and business-related strategy alignment elements. The following is the results of carrying out this research on the social network structure and features of strategy alignment elements for a digital library. First, analysis indexes for strategy alignment elements and social network of a digital library were developed. Second, an analysis model was designed based on the analysis index for social network as to strategy alignment elements. Analysis model was appraised by collecting social network datasets for such strategy alignment elements as Communications, Competency and Value, Governance, Partnership, Scope and Architecture, and Skills against the Business strategy, Information strategy, Business and Technology of a digital library. As for the content of analysis, social network structure and specific features were analyzed in relation to a digital library's (1) General social network, (2) Structure of strategy alignment elements, (3) Strategy fit and Functional integration.