• 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.

• Environmental Analysis Health and Toxicology
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• v.19 no.2
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• pp.161-167
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• 2004

Air quality monitoring is a primary activity for industrial and social environment. The government identifies the pollutants that each industry must monitor. Especially, the VOCs (Volatile Organic Compounds), which are very harmful to human body and environment atmosphere, should be controlled under the government policy. However, the VOCs, which have not been confirmed in emission sources are very difficult to monitor. It is needed to develop the monitoring system that allow the continuous and in situ measurement of VOCs mixture in different environmental matrices. Gas chromatography and mass spectrometry are the most prevalent current techniques among those available for the analysis of VOCs. But, they need a large size analytical instrument, which costs a great deal for purchase and operation. In addition, it has some limitations for realtime environmental monitoring such as location problems and slow processing time. Recently, several companies have commercialized a portable VOCs measurement systems, which cannot classify various kinds of VOCs but total quantities. We have developed a VOCs measurement system, which recognizes various kinds and quantities of VOCs, such as benzene, toluene, and xylene (BTX). Also, it can be used as a stand- alone type and/or fixed type in the vehicle with rack for real -time environmental monitoring.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1628-1639
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• 2015

Line-interactive uninterruptible power supply (UPS) systems are good candidates for providing energy storage within a microgrid. In this paper, a control scheme for a line-interactive UPS system applied in a low-voltage microgrid is presented. It is based on the Q-w and P-E droop control to achieve a seamless transition between grid-connected and stand-alone operation modes. Moreover, a new model for designing the controllers is built in the dq-frame based on the instantaneous power definition. The new-built model takes into account the dynamic performance of the output impedance of the inverter in the dq-frame and can be evaluated in the time domain. Compared to the traditional model based on the instantaneous power definition, the new-built model is more accurate to describe the dynamic performance of the system. Simulation and experimental results obtained with a microgrid consisting of two 40-kW line-interactive UPS systems are given to validate the control strategy of the line-active UPS system and the accuracy of the new-built model.

• 한국태양에너지학회:학술대회논문집
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• 2008.04a
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• pp.80-85
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• 2008

A PVIB(Photovoltaic in Building) system is united by a constituent outer covering and can expect dual effects that reduce expenses for the establishment of a PV system. It is a profitable technology because it does not need a building as it is a stand alone PV system. This paper presents design, operational features analysis, and PCS(Power Conditioning System) of grid-connected 30kW PVIB set up on the library of Dongshin University. For a sustainable photovoltaic system in this area, the data of the PVIB system are collected and analyzed by monitoring system using LabView. PCS of the grid-connected PVIB system, also, is designed for optimal operation with characteristics suggested in this paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.18 no.1
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• pp.26-36
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Journal of the Korean Society for Library and Information Science
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• v.45 no.3
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• pp.69-85
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• 2011

This study reviewed theories for database integration, which combines heterogeneous data structures, and suggested a practical method to integrate databases of Korean Research Memory(KRM) and Infrastructural Basic Research(IBR) as a case study. In order to broadly distribute the outcomes of IBR, it is essential to be connected to and integrated with the database of KRM. As a solution, it was suggested that the current database of IBR should follow standard guidelines as a XML database, and its future database should be integrated with the database of KRM or be established as a stand-alone system

• Journal of Industrial Technology
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• v.25 no.A
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• pp.81-86
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• 2005

A vibration monitoring system for a small class of wind turbine (W/T) is established and operated. The monitoring system consists of monolithic integrated chip accelerometer for vibration monitoring, anemometers for wind data acquisition and auxiliary sensors for atmospheric data. Using the monitoring system, vibration response of a 6kW W/T generator is investigated. Acceleration data of the W/T tower under various operation condition is acquired in real time using LabVIEW and is remotely transferred from the test site to the laboratory in school by internet. Vibration state of the tower structure is diagnosed within the operating speed range. Resonance frequency range of the test model is investigated with the wind speed data of the test site.

• Proceedings of the KIPE Conference
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• 2013.07a
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• pp.323-324
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• 2013

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charge mode, constant-current mode, and constant-voltage mode. The pre-charge mode employs the stair-case shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is specified to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 78A. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• Journal of the Korean Solar Energy Society
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• v.22 no.3
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• pp.67-76
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• 2002

Data-Acquisition systems are widely used in Photovoltaic(PV) system application in order to analyze and optimize the performance of PV systems. In this paper, the development of a computer-based data-acquisition system and its application are described. The proposed Computer-based data-acquisition System consists of a set of sensors for measuring both environmental and electrical parameters. The collected data are first conditioned and then interfaced to PC using a data-acquisition card. The Labview program was used to further process, display on the monitor at real time and store on the hard disk. We designed and installed two stand-alone PV systems to supply different loads, which in this case a Low Pressure Sodium(LPS) 55 [W] lamp and a electrodless 55 [W] lamp. When the proposed data acquisition system is applied on the designed PV systems, Optimized system operation methods are investigated to confirm a stable load availability and extend battery life time.

• Journal of The Korea Institute of Healthcare Architecture
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• v.23 no.3
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• pp.81-90
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• 2017

Purpose: The regional trauma center should be a trauma treatment center equipped with facilities, equipment, and manpower capable of providing optimal treatment such as emergency surgery to a severely traumatized patient upon arrival at the hospital. In order to establish a medical system for effective severe diseases, it is necessary to prepare architectural planning guidelines for the regional trauma centers. Methods:: Analyze the spatial configuration, and the area composition of the regional trauma center, And to provide basic data for building a more efficient regional trauma center. The spatial composition analysis divides the space into initial care, resuscitation, patient area, nursing area, diagnostic test, staff training, staff support, public, and analyzes the area and interconnection of each space. Results: The area that must be included in the regional trauma center is the resuscitation area, the patient area, the diagnostic examination area, architectural planning should be designed to enhance the interconnection of the areas. IIn addition, a regional trauma center should be planned as a separate from the existing facility so that it can be installed and operated independently. Implications: A regional trauma center should be built as a stand alone operation and the space should be planned as a more efficient route.