• Journal of the military operations research society of Korea
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• v.1 no.1
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• pp.131-135
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• 1975

One of the pending issues of the Ministry of Defense is the efficient management of space parts for the weapon systems. It has been known that more than 000 million dollars are needed for spare parts for the weapon systems annually. Though the problem demands a serious consideration, there has not been any systematic study on the problem as far as the author knows. One way to approach the problem is through an investigation of the system reliability under constraints. A measure of how well a system performs or meets its design objectives is provided by the concept of system reliability. If successful operation is desired for a specified period of time, reliability is defined as the probability that the system will perform satisfactorily for the required time period. This interpretation of reliability is normally applied to devices which are subject to random failures such as electrical or mechanical systems. It has been found necessary to express system reliability in terms of the reliability of the components or subsystems which comprise the system. The major subsystems of an aircraft, for example, include the electronics, powerplant, airframe and armament subsystems. Therefore, the optimal spare part kit can be found by maximizing the system reliability subject to cost or other constraints.

• Journal of Korean Library and Information Science Society
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• v.42 no.1
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• pp.299-324
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• 2011

This study focuses on whether early childhood education institutes operate libraries and find out if those environments are suitable for reading, and to investigate on educations on reading by utilizing libraries and how it's perceived by surveying and analyzing. As a result, it was found that there were higher rate of institutions with active libraries and as for the reasons for needing an assigned librarian were found to be in the order of 'to educate young children for reading' and 'for the systematic management of books'. Points of necessity for the efficient reading education was found to be 'establishing of staff system with professional knowledge' and 'development of reading education programs.'

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.3
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• pp.231-237
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• 2016

Recently, the interest in DC systems to achieve more efficient connection with renewable energy sources, energy storage systems, and DC loads has been growing extensively. DC systems are more advantageous than AC systems because of their low conversion losses. However, the DC-link voltage is variable during operation because of different random effects. This study focuses on DC voltage stabilization applied in stand-alone DC microgrids by means of voltage ranges, power management, and coordination scheme. The quality and stability of the entire system are improved by keeping the voltage within acceptable limits. In terms of optimized control, the maximum power should be tracked from renewable resources during different operating modes of the system. The ESS and VSDG cover the power shortage after all available renewable energy is consumed. Keeping the state of charge of the ESS within the allowed bands is the key role of the control system. Load shedding or power generation curtailment should automatically occur if the maximum tolerable voltage variation is exceeded. PSIM-based simulation results are presented to evaluate the performance of the proposed control measures.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.1
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• pp.106-111
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• 2010

Electronic watt hour meters(WHM) for high pressure running in domestic were installed to the digital type meter and ones for low pressure are expected to complete within several years. Domestic power metering technology is being beyond a simple framework with an electronic type and is rapidly evolving to intelligent smart metering systems in conjunction with promotion of a national smart grid project. Major policy outlook of the world's major power company regarding Intelligent metering is the application of the fare structure diversification and is the improvement of level of service to customers. In addition, electric power companies should focus on the cost reduction and the improvement of management efficiency through an efficient operation of distribution facility. In this paper, we are about to make an observation of the additional services technology development trend of the overseas smart meter and to have a view of value-added services(VAS) system of smart meter suitable for the domestic environment based on the technology development of VAS utilizing electronic watt hour meter performed by recent research projects.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.46
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• pp.181-210
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• 2010

The continuing advance of multimodal transport with the importance for efficient and effective logistics management emphasizes the need for uniform legal approach to international multimodal transport. However, the current fragmented instrument regulating such transport is being an obstacle to development of multimodal transport as it aggravates confusion and uncertainty. The Rotterdam rules, which was adopted in December 2008 by UNCITRAL, expands its scope of application to door-to-door transport. However, the new rules has some problems in its application to multimodal transport operation as it has been conceived not to regulate general multimodal carriage but to regulate contract of carriage by sea that extends its services to the transport by other modes. This article examines conflict of conventions in the Rotterdam Rules. The applicability of the Rotterdam Rules in international multimodal transport contract and possibility of potential conflict with other transport conventions are analyzed with some hypothetical cases. Furthermore, problems arising from application of the Rotterdam Rules under international multimodal transport Contracts are indicated in the chapter IV.

• Journal of the Korean Institute of Rural Architecture
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• v.11 no.4
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• pp.17-24
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• 2009

To ensure the revitalization of rural communities with viable levels of population, various agricultural policies are needed. Attaining this goal demands a comprehensive plan to improve rural housing conditions in general, along with more proactive policies dealing with existing rural housing problems by providing public housing options. The purpose of this paper is to suggest a set of base data which can provide direction when proposing prospective housing policies which comply the peculiar and changing needs of rural communities. To establish the base data, the study reviewed all the relevant issues, requirements and resources in the course of developing rural housing regulations and policies. Some municipal organizations have implemented independent housing programs for returning farmers. They provide one-stop service corners to provide returning farmers comprehensive counseling and information about employment, child-rearing and education, housing, and etc. in their municipals. Agricultural housing projects nowadays focus on promoting voluntary establishments of local communities by providing comprehensive plans for public housing, idyllic housing and other interchange facilities. Recent trends on housing project take into consideration both residential areas and their surrounding landscapes at minimum investment possible. The efficient investment of regional housing development lies in the simultaneous consideration on both the construction and operation and management of housing development from beginning to end.

• The Transactions of the Korea Information Processing Society
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• v.5 no.10
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• pp.2467-2478
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• 1998

The spatiotemporal databases support historical informations as well as spatial managements for the objects in the real world, and can be efficiently used to various applications such as geographic information system, urban plan system, car navigation system. Although there are so far several pioneering works in spatioemporal data modeling, it is little to study on spatiotemporal query language. So in this paper, we at first survey a modeling technique that makes spatiotemporal objects into databases, and then show some sighificant functions supported by query language. Also we suggest a new spatiotemporal database query language, entitled as STQL, which make users to enable to manage efficient historical information as well as spatial management function on the basis of relational query language, SQL. Also the proposed STQL, shows their operationsl in spatiotemporal daabases.

• Journal of Digital Convergence
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• v.11 no.4
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• pp.279-284
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• 2013

Improve the global environment for low carbon emissions and green energy, and the growing interest in IT technology, combined with the existing power grid to achieve this, to achieve more efficient and environment-friendly smart grid smart grid projects around the world actively being deployed. A smart grid is expected to be a modernization of the legacy electricity network. Therefore, this research provides a secure smart grid model so that it provides better monitoring, protecting and optimizing automatically to operation of the interconnected elements.

• Proceedings of the KIEE Conference
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• summer
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• pp.120-122
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• 2004

This paper analyse impacts of Community Energy System (CES) on the grid during transition periods for integrating of the CES and the grid. In the near future, CES might be one of major energy supply structures. The basic concept of CES is that it supplies electrical and thermal energy to the local customer loads through the islanded power network separated from the grid. Therefore, the interconnection with the grid occurs only when the energy supply from the CES generators does not meet the demand of the local load. For avoiding impacting the grid during the transition operation modes of CES, it is necessary to thoroughly analyse the influences on the grid during those periods. In order to show them, in this paper, we model the CES with 2.34 WVA DG and simulate the impacts on the grid due to interconnection of CES The simulation results show that, in order to reduce bad influences of CES on the grid, CES need the efficient load management and generation control schemes during the transition periods.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.532-539
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• 2010

The high tech marine transportation infrastructure is an innovative transportation infrastructure that may be able to secure a safe transportation environment as well as efficient operation by connecting up-to-date skills including a broad range of wire and wireless communication-based information, control and electronics technologies. When integrated into the marine transportation infrastructure by the standard requirements, these standard technologies help monitor and manage navigational aids. After investigated on current status of marine transportation system, verified on integrating marine transportation systems, the standard requirements have to suggest a appropriate way of integrating marine traffic systems and proper way of using old marine traffic infrastructure.