• The Transactions of The Korean Institute of Electrical Engineers
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• 제58권7호
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• pp.1349-1355
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• 2009

This paper is studied on a novel power factor correction (PFC) AC-DC converter of high efficiency by soft switching technique. The input current waveform in the proposed converter is got to be a sinusoidal form composed of many a discontinuous pulse in proportion to the magnitude of a ac input voltage under the constant switching frequency. Therefore, the input power factor is nearly unity and the control method is simple. The proposed converter adding an electric isolation operates with a discontinuous current mode (DCM) of the reactor in order to obtain some merits of simpler control, such as fixed switching frequency, without synchronization control circuit used in continuous current mode (CCM). To achieve the soft switching (ZCS or ZVS) of control devices, the converter is constructed with a new loss-less snubber for a partial resonant circuit. It is that the switching losses are very low and the efficiency of the converter is high, Particularly, the stored energy in a loss-less snubber capacitor recovers into input side and increases input current from a resonant operation. The result is that the input power factor of the proposed converter is higher than that of a conventional PFC converter. This paper deals mainly with the circuit operations, theoretical, simulated and experimental results of the proposed PFC AC-DC converter in comparison with a conventional PFC AC-DC converter.

• Journal of Korea Multimedia Society
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• 제15권5호
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• pp.624-631
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• 2012

For many medical imaging systems, volume datasets are stored as a compressed form, so that the dataset has to be decompressed before it is visualized. Since the decompression process takes quite a long time, we present an acceleration method for medical volume decompression using GPU. Our method supports that both lossy and lossless compression and progressive refinement is possible to satisfy variable user requirements. Moreover, our decompression method is well parallelized for GPU so that the decompression takes a very short time. Finally, we designed that the decompression and volume rendering work in one framework so that the selective decompression is available. As a result, we gained additional improvement in volume decompression.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.511-514
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• 2007

Gas hydrate has a unique property that can store a large volume of gas in water as a solid form. Even though investigations for natural gas storage technology have been carried out for several decades, there are still a lot of unsolved problems due to complex formation process, low formation speed, high energy consumption and so on. So, lots of experiments were conducted to overcome these weaknesses and to develop artificial NGH formation technology applicable to industrial-scale storage and commercial transport. In this study, some series of experiments were performed to analyze both stirred and unstirred system especially about the influences of several gas hydrate formation factors such as agitation speed, system temperature, SDS concentration, etc. As a result, optimum range of SDS concentration and temperature that could enhance the storage capacity and shorten the formation time were found. And it is obviously presented that SDS such a kind of surfactant promotes gas hydrate formation dramatically and the quantity of stored gas are proportional to agitation speed in stirred system.

• Journal of Computing Science and Engineering
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• 제4권4호
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• pp.291-312
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• 2010

The last decades a large amount of research has been done in the genomics domain which has and is generating terabytes, if not exabytes, of information stored globally in a very fragmented way. Different databases use different ways of storing the same data, resulting in undesired redundancy and restrained information transfer. Adding to this, keeping the existing databases consistent and data integrity maintained is mainly left to human intervention which in turn is very costly, both in time and money as well as error prone. Identifying a fixed conceptual dictionary in the form of a conceptual model thus seems crucial. This paper presents an effort to integrate the mutational data from the established genomic data source HGMD into a conceptual model driven database HGDB, thereby providing useful lessons to improve the already existing conceptual model of the human genome.

• Korean Management Science Review
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• 제12권2호
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• pp.129-146
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• 1995

As society's relience on computerized information systems to support a wide range of activities proliferates, the long recognized importance for adequate data quality becomes imperative. Furthermore, current trends in information systems such as dispersal of the data resource together with its management have increased the difficulty of maintaining suitable levels of data integrity. Especially, the importance of adequate accounting (transaction) data quality has been long recognized and many procedures (extensive and often elaborate checks and controls) to prevent errors in accounting systems have been introduced and developed. Nevertheless, over time, even in the best maintained systems, deficiencies in stored data will develop. In order to maintain the accuracy and reliability of accounting data at certain level, periodic internal checks and error corrections (internal audits) are required as a part of internal control system. In this paper we develop a general data quality degradation (error accumulation ) and cost model for an account in which we have both error occurrences and error amounts and provide a closed form of optimal audit timing in terms of the number of transactions that should occur before an internal audit should be initiated. This paper also considers the cost- effectiveness of various audit types and different error prevention efforts and suggests how to select the most economical audit type and error prevention method.

• Proceedings of the Korea Contents Association Conference
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• 한국콘텐츠학회 2004년도 추계 종합학술대회 논문집
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• pp.466-469
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• 2004

XMLis that XML developers in client application data text base format that can express and deliver and exchange structured data to display and manufacture. Store Spatial XML to RDBMS actually and is using to useful data that do geography information there is many interests in utilization that Spatial XML including Spatial information does it appearing to this XML Wish to search Spatial XML about data that is stored to RDBMS using Spatial XQuery to ask a question in this paper and embody Spatial XML Generator algorithm that draw information in RDBMS in XML form through Spatial XML Generator also.

• Journal of Korea Multimedia Society
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• 제9권12호
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• pp.1552-1559
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• 2006

In a web environment, similar information exists in many different places in diverse formats. Even duplicate information is stored in the various databases using different terminologies. Since most information serviced in the current World Wide Web however had been constructed before the advent of ontology, it is practically almost impossible to construct ontology for all those resources in the web. In this paper, we assume that most information in the web environment exist in the form of RDBMS, and propose a matching method between domain ontology and existing RDBMS tables for semantic retrieval. In the processing of extracting a local ontology, some problems such as losing domain in formation can occur since the correlation of domain ontology has not been considered at all. To prevent these problems, we propose an instance-based matching which uses relational information between RDBMS tables and relational information between classes in domain ontology. To verify the efficiency of the method proposed in this paper, several experiments are conducted using the digital heritage information currently serviced in the countrywide museums. Results show that the proposed method increase retrieval accuracy in terms of user relevance and satisfaction.

• Journal of the Korea Computer Industry Society
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• 제2권3호
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• pp.321-328
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• 2001

Existing internet auction systems have adopted the form which gives a win to the auction bidder who proposes the top bid price for the goods posted on the auction board. But they haven't been satisfying the automatical one-step processing for user’s convenience because they must require continuous care of user for bidding and checking as well as neglecting the convenience of user interface while participating in the electronic bidding system. The agent push mail to a auctioneer information that able to get how much profit as calculate duration time and start price with bidding history stored database. So, this thesis propose a multi-agent system in internet auction that generate the highest margin for auctioneer’s goods.

• Journal of Korean Society for Geospatial Information Science
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• 제2권2호
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• pp.99-108
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• 1994

In this thesis, we propose the 3D terrain modelling method for the better understanding of the geographic information. The process of 3D terrain medelling consists of three steps. The first step is to obtain real-world data from satellite images and stored in the form of DEM(Digital Elevation Model). The second one is to extract the meaningful data from DEM data based on LOD(Level Of Detail). And the third is to construct the 3D surface by TIN(Triangulated Irregular Network) with the extracted meaingful data. The proposed dynamic TIN reconstruction algorithm locally reconstruct the existed TIN model with the additional a new point. In this way, we can construct the TIN with the reduced time and can simulated 3D terrain model in real time.

• Proceedings of the KOSOMBE Conference
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.253-256
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• 1997

KESF-1 foot conceptually provides storage of potential energy and is converted to kinetic energy throughout the weight - bearing phase of the gait cycle. This stored energy is progressively released as the foot continues through the toe-off phase to rebound and propel the body forward. A weight deflects the keel through a predetermined range, then the keel "springs back" as weight is removed. Foot designs criteria were selected to guide development beyond the proof-of concept composite material keels; 1) store and return energy (1-3/4 " metatarsal deflection at 435 pounds vertical load), 2) natural feel and stability; 3) useful life of 3-years: 4) lightweight; 5) reduced production costs. The purpose of this study is developed the comfortable stable foot that fitted with Korean lifestyle and road condition. The results produced the realistic cosmetic foot cover with polyurethane form and the keel composed with composite materials of both glass fiber and carbon fiber.