• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.4
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• pp.366-373
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• 2005

This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.

• Journal of the Korean Regional Science Association
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• v.8 no.1
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• pp.31-50
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• 1992

The aim of this paper is to define major factors influencing land development of each of major uses (residential, commercial, industrial) in the process of rapid urban expansion. The main hypothesis of this study is that land use changing patterns are directed by supply side of land managed to public policies rather than demand side. The graphic analysis is applied to relationships between urban growth and land development process of each use and between land development project managed to public policies and land development process. Public and land development projects and zonning protection seem to be major roles of land supply and main determinants of urban spatial structure. Location factors for land development of each uses are selected in 23 variables. Factor analysis is applied to test correlation between variables in 1971 and 1981. Factor structure between two years is similar, but progressive processing of functional separation is derived such as intensive land use is grouped, different location between residential and industrial use is deep. Dependent variables are standardized to logarithm of land development of each use per unit vacant land in two periods, between 1971 and 1980 year and between 1981 year. Correlation analysis between 6 dependent variables and 23 location factors in each years are applied. Major factors of each use are selected in criteria such as high correlation with dependent variables, low correlation between independent variables and common application in two periods. As the result, major factors for residential land development are Land Readjustment Project (LRP), percent of total zoned area in residential zone, residential floor space density per available area, percent of total area in industrial use; for commercial development is distance to CBD, percent of total area in commercial use, residential floor space density per available area in each year, and volumn rate of industrial use; for industrial use is percent of total area of industrial use is percent of total area of industrial use, Industrial Estate Project (IES), LRP, and distance from CBD. Land development pattern of each use between two periods are slightly different. So 6 equation is derived from appling backward method of regession. Adjusted multiple R squares of all is more than 0.5 and those equation is statistically significant and valuable to assist urban land use forecasting.

• Health Policy and Management
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• v.11 no.1
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• pp.107-130
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• 2001

During the last year, we had a very severe situation with the strike of physicians working in medical facilities. From that time, many politicians and scholars insisted on the expansion of public hospitals to enhance the public role in the medical care sector. They think that private medical facilities work for profit motivation and that the high proportion of private to whole facilities is an obstacle to the public function of medical care under social insurance system. They found that one of the reasons for failing to prevent the physicians' strike was the high proportion of private facilities. Others insisted that the strike was not a good reason for the expansion of public hospitals. The physicians' strike was a very rare case, and it is not a good basis for generalization of the discussion of public hospitals. Last year almost all apprentice physicians in public facilities took part in the strike, and consequently the public hospitals also lost the role of public function. They view this increasing involvement of government in the medical sector as improper and the cause of inefficiencies. In this paper we review the debate over the expansion of public facilities. To clarify the debate, we review traditional criteria for the role of government in a market system and to apply these criteria to medical care. There are two traditional areas where government Is acknowledged to have a role in a market system: market imperfections and market failure. Where market imperfections and market failure exist, there may be a role for government. The justifications for government intervention are consumer protection and the existence of externalities. One of externalities is to provide medical care for the poor. The appropriate measures to provide medical owe to the poor can be sought in both demand and supply side subsidies. National health insurance is a method of demand subsidies and establishment of public hospitals is a method of supply side subsidies. Under the National Health Insurance System, the expansion of public hospitals is not an appropriate subsidy policy.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.23-29
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• 2003

It has been declared in 1992 at Rio about the management of united water control and method of the management of the water resources at the water basin. And it was also mentioned about the protection of fresh water's quality and it's supply under chapter the 18th of the agenda 21. It has been 10years passed after Rio declaration, and water crisis Is getting more serious than before. Fairly, right for using water resources was given to every life as the public resources. But at the last world water forum, water was commercialized, and regulated as the basic requirement not basic right. Therefore, we could use the water according to the logic of supply and demand at the market, and with money. Furthermore, construction of the big dam which was build to solve the problem of the lack of water became one of problems for water control. Korea is keeping consistent policy such as providing water by the building of dam. Control of the water demand is the most basic and effective policy for the preservation of water resources. If we change the policy such as the construction of the dam, we should put the management of the water demand in the center with the reliable philosophy. United management of the river basin has to be made with the security of water, improvement of water quality, and protection of the ecological side each other. Management of water basin also has to be completed to solve the trouble caused by using water conflict people who live up and down stream. To maintain the good quality of water, management of water basin is necessary. Also, bottom line of the united management of water basin is voluntary involvement of every citizens and local community. We suggest to preserve the origin of river and the upper at the ecological side. It is worth it to preserve.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.12
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• pp.2633-2640
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• 2009

We design a small-area, low-power, and high-speed EEPROM for touch screen controller IC. As a small-area EEPROM design, a SSTC (side-wall selective transistor) cell is proposed, and high-voltage switching circuits repeated in the EEPROM core circuit are optimized. A digital data-bus sensing amplifier circuit is proposed as a low-power technology. For high speed, the distributed data-bus scheme is applied, and the driving voltage for both the EEPROM cell and the high-voltage switching circuits uses VDDP (=3.3V) which is higher than the logic voltage, VDD (=1.8V), using a dual power supply. The layout size of the designed 128-KBit EEPROMIP is $662.31{\mu}m{\times}1314.89{\mu}m$.

• Journal of Korea Port Economic Association
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• v.39 no.2
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• pp.195-204
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• 2023

In this study, the causes of the boom in the container shipping industry pointed out by the media were analyzed. As a result of the analysis, it was found that on the supply side, shipping companies mooring ships in response to IMO environmental regulations caused a rise in freight rates due to 'ships that could not be operated' even if demand increased. In terms of demand, it was determined that the claim that social distancing promoted purchases and increased demand was somewhat unfounded. The reason is that the relationship between social distancing and rising fares is weak.

• Journal of Practical Agriculture & Fisheries Research
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• v.26 no.1
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• pp.30-39
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• 2024

Korean arboretums where a large number of people are visiting could not do visitor's satisfaction in qualitative side and communication through education and event, although a lot of those things statistically have been doing so far. At this side, it needs an arboretum's segmentation: preparing to an adaptation strategy of a new paradigm, differentiated strategy, and problem solving strategy tied by a similar group for the Korean arboretum visitors. This research tries to classify several patterns with Korean arboretums by visitor's behavior and propose each type of subspecialized management plan after analyzing characteristic of supply and demand. The research for this tries to classify several patterns of Korean arboretum and suggest segmentalzed management plan by types after analyzing characteristics of aspects of demand and supply. By looking at the main patterning result of arboretum as a standard of the demand, there were four sorts of arboretums. In the first, it is the arboretum of intermediate type: not a clear characteristic. In the second, it is an arboretum of multipurpose resort type: strongly demanding motivational factors of a rest, health, access, low cost, experience, learning and sightseeing. In the third, it is an arboretum of theme tour type: a strong sightseeing motivational factor and demanding appreciate scenery. In the last, it is an arboretum of studying and admiring type: demanding a motivational factor of sightseeing landscape and plants, a strong experience and learning.

• Journal of Intelligence and Information Systems
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• v.9 no.1
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• pp.1-21
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• 2003

As electronic commerce(EC) has grown rapidly, agents that work on the behalf of humans on the Internet are being used actively. However, most of the EC agents have some problems. They fail to fully support buyers' decision making behaviors and sellers' information supply activities. Further, they are not suited for mobile computing environment. In this paper, we introduce a Multi-Mobile Agents System(MMAS) that has been developed according to a conceptual framework that corrects the aforementioned problems. Built by using Tokyo IBM ASDK(Aglets Software Development Kit) for the area of hotel reservation, the system consists of buyer- and seller-side agents that interact with each other; buyer-side agents help buyers to make purchasing decisions by collecting and analyzing information through applying a multi-criteria decision making method, while seller-side agents substitute fur sellers by managing databases and providing real-time information to the buyer-side agents. In this system, multiple agents perform their shared tasks at the same time in order to increase efficiency. Users do not have to keep the connection with the system because they are notified when tasks are done.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.3
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• pp.1302-1307
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• 2011

The Spiral coil is made considering primary, secondary side coil inductance, turn number, size, thickness, and shielding area with the litz wire-type in case of manufacturing a coil, and at this time, the semi-automation winding machine is used. When deciding on primary and secondary side coil specification and manufacturing a coil, the spiral coil of a specification varied in the various litz wire of a specification is required, and at this time, a difficulty is generated by the manufacture cost, period which during, and failure the manufacture is generated in the coil sample making. A difficulty is in the desired coil quality control of a specification. Since improving the rectifier of the secondary side in order to improve this kind of problem, the range of the coil design and the during the manufacture, various coil manufacture specifications can be comprehensively made.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.269-274
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• 2011

A CFD analysis was performed to examine the inner channel blockage of dual-cooled fuel which has being developed for the power uprate of a pressurized water reactor (PWR). The dual-cooled fuel consists of an annular fuel pellet($UO_2$) and dual claddings as well as internal and external cooling channels. The dual-cooled annular fuel is different from a conventional solid 려el by employing an internal cooling channel for each fuel pellet as well as an external cooling channel. One of the key issues is the hypothetical event of inner channel blockage because the inner channel is an isolated flow channel without the coolant mixing between the neighboring flow channels. The inner channel blockage could cause the Departure from Nucleate Boiling (DNB) in the inner channel that eventually causes a fuel failure. This paper presents the CFD simulation of the flow through the side holes of the bottom end plug for the complete entrance blockage of the inner channel. Since the amount of coolant supply to the inner channel depends on largely the pressure loss at the side hole, the pressure loss coefficient of the side hole was estimated by the CFD analysis. The CFD prediction of the loss coefficient showed a reasonable agreement with an experimental data for the complete blockage of both the inner channel entrance and the outer channel. The CFD predictions also showed the decrease of the loss coefficient as the outer channel blockage increases.