• Journal of Korean Society of Water and Wastewater
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• v.31 no.2
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• pp.177-186
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• 2017

This study concerned the analysis on the efficiency of the conversion of water tank type supply system to direct water supply system to examine the feasibility of the conversion, as well as the calculation of optimal conversion range that enables the supply of safe, high-quality water at stable pressure in accordance with the standards of water supply facility. The results of this research showed that when converting water supply system from water tank type supply system to direct water supply system, more nodal points could be properly converted and more reduction of electricity usage was expected in case water pressure rather than residence time was fixed. This means that higher efficacy can be obtained by fixing water pressure when converting water supply system. However, since the number of the locations that received on-spot inspection was small and the electricity usage measured was not exclusively by water supply facility, it is difficult to judge that such reduction of electricity usage accurately represents reduced electricity usage by water supply facility alone. therefore, after having secured on-spot information about a larger number of locations in apartment complexes that have converted water supply system, and utilizing information about electricity usage exclusively by water supply facility, the proposed method of this research could be applied to accurately deducing expected reduction of electricity usage by water supply facilities of various other apartment complexes. It is also considered possible to deduce an effective operation method of water supply system by finding out an area that shows low pressure or low residual chlorine concentration in the optimal conversion range of water supply, followed by estimating the proper location of pumping station or the proper chlorine dosage at the power purification plant that supply water to the target area.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.27-33
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• 2012

Internet Data Centers (IDC), as essential facilities for modern IT industry, typically have scores of MW of concentrated electric loads. Uninterruptible Power Supplies (UPS) are necessary for the power feed system of IDCs because of stable power requirement. Thus, conventional AC power feed systems of IDCs have three cascaded power conversion stages such as (AC-DC), (DC-AC), and (AC-DC), which results in very low conversion efficiency. On the contrary, DC power feed systems need just a single power conversion stage (AC-DC) supplying AC mains power to DC server loads, which gives comparatively high conversion efficiency and reliability. This paper compares the efficiencies between 220V AC power feed system and 300V DC power feed system on equal load conditions which were established in Mok-Dong IDC of Korea Telecom company (KT). Experimental results show that the total operation efficiency of the 300V DC power feed system is around 15% higher than that of the 220V AC power feed system.

• ETRI Journal
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• v.27 no.5
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• pp.579-584
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• 2005

A CMOS direct-conversion mixer with a single transistor-level topology is proposed in this paper. Since the single transistor-level topology needs smaller supply voltage than the conventional Gilbert-cell topology, the proposed mixer structure is suitable for a low power and highly integrated RF system-on-a-chip (SoC). The proposed direct-conversion mixer is designed for the multi-band ultra-wideband (UWB) system covering from 3 to 7 GHz. The conversion gain and input P1dB of the mixer are about 3 dB and -10 dBm, respectively, with multi-band RF signals. The mixer consumes 4.3 mA under a 1.8 V supply voltage.

• Journal of Society of Preventive Korean Medicine
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• v.10 no.2
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• pp.147-158
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• 2006

The purpose of this paper is to review the empirical study results of conversion factors(unit prices) for relative values of health care services in the national health insurance system and establish optimal classification of health care institutions for feasible contract of conversion factors between National Health Insurance Corporation(NHIC) and provider groups, based on legal backgrounds and types of health care service delivery system. some empirical research evidences shows the validity of applying multiple conversion factors to annual contract for reimbursement in the national health insurance. Policy recommendations suggest that clinic, hospital, general hospital, tertiary hospital, dental clinic, oriental medical clinic, pharmacy, and public health centers would be a basic category of provider groups for a meaningful price contract between the NHIC and providers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.4
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• pp.412-422
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• 1989

The need to conversion between NAS and CEPT networks has led to the development of PCM standards conversion techniques, especially signalling conversion techniques. This paper contains a brief description and general overview of channel associated signalling(CAS) of 24-channel system and of 30-channel system. The line signalling conversion algorithm between two systems and the transition detection algorithm of call status is proposed. And this paper presents the effective inplementation techniques of these algorithm.

• Journal of Power System Engineering
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• v.20 no.2
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• pp.79-84
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• 2016

The thermodynamic performance of ocean thermal energy conversion with 1 kg/s geothermal water flow rate as a heat source was evaluated to obtain the basic data for the optimal design of cycle with respect to the classification of the working fluid. The basic thermodynamic model for cycle is rankine cycle and the geothermal water and deep seawater were adapted for the heat source of evaporator and condenser, respectively. R245fa, R134a are better to use as a working fluid than others in view of the use of geothermal water. It is important to select the proper working fluid to operate the ocean thermal energy conversion. So, this paper can be used as the basic data for the design of ocean thermal energy conversion with geothermal water and deep seawater.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.2
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• pp.134-139
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• 2003

This study was carried out to investigate the aging and conversion characteristics of oxidation catalysts for a natural gas vehicle with lean-bum system. The conversion of $CH_4$ was observed over the various composition ratio of PMs(Precious metals) and washcoating methods. On the fresh catalysts, Pd affected on the activity of $CH_4$ at low temperature more than other PMs in Pd-only and Rh/Pd/Pt catalysts. The activity at low temperature increased as a mount of Pd increases. On the aged catalysts, the $CH_4$ conversion efficiency of Pd-only catalyst with mono-layer washcoat decreased more than that of the other catalysts of $CH_4$ conversion. It was observed that the thermal durability of Rh/Pd/Pt catalysts with double-layer washcoat was better than the single washcoat catalyst.

• Proceedings of the IEEK Conference
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• 2000.07b
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• pp.1001-1004
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• 2000

RFID system is applied to identify, locate and track people, cars, animals. In RFID system, the passive transponder without battery has some benefits than active transponder, such as no restriction in battery exchange and in battery’s life. But it needs auxiliary RF-DC conversion circuit. RF-DC conversion circuit originated from Wireless Power Transmission (WPT). In this paper, RF-DC conversion circuit consists of a microstrip patch antenna and impedance matching circuit, Cock-croft Walton circuit. And RF-DC conversion circuits have two kinds of T-type and Cross-type impedance matching circuits.

• Language and Information
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• v.7 no.2
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• pp.81-101
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• 2003

This paper introduces a computerized version of the Korean Standard Pronunciation Rules that can be used in speech engineering systems such as Korean speech synthesis and recognition systems. For this purpose, we build Petri net models for each item of the Standard Pronunciation Rules, and then integrate them into the sound conversion table. The reversion of the Korean Standard Pronunciation Rules regulates the way of matching sounds into grammatically correct written characters. This paper presents not only the sound conversion table but also the character conversion table obtained by reversely converting the sound conversion table. Malting use of these tables, we have implemented a Korean character into a sound system and a Korean sound into the character conversion system, and tested them with various data sets reflecting all the items of the Standard Pronunciation Rules to verify the soundness and completeness of our tables. The test results show that the tables improve the process speed in addition to the soundness and completeness.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.503-512
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• 2012

There is a new power generation system such as direct coal fuel cell (DCFC) with a solid oxide electrolyte operated at relatively high temperature. In the system, it is of great importance to feed coal continuously into anodic electrode surface for its better contact, otherwise it would reduce electrochemical conversion of coal. For that purpose, it is required to improve the electrochemical conversion efficiency by using either rigorous mixing condition such as fluidized bed condition or just by recirculating coal particle itself successively into the reaction zone of the system. In this preliminary study, we followed the second approach to investigate how significantly particle recycle would affect the coal conversion efficiency. As a first phase, coal conversion was analyzed and evaluated from the thermochemical reaction of carbon with air under particle recirculating condition. The coal conversion efficiency was obtained from raw data measured by two different techniques. Effects of temperature and fuel properties on the coal conversion are specifically examined from the thermochemical reaction.