• Journal of KIISE:Computing Practices and Letters
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• v.15 no.12
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• pp.963-967
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• 2009

The Log-structured File System (LFS) collects all modified data into a memory buffer and writes them sequentially to a segment on disk. Therefore, it has the potential to utilize the maximum bandwidth of storage devices where sequential writes are much faster than random writes. However, as disk space is finite, LFS has to conduct cleaning to produce free segments. This cleaning operation is the main reason LFS performance deteriorates when file system utilization is high. To overcome painful cleaning and reduced performance of LFS, we propose the segment space recycling (SSR) scheme that directly writes modified data to invalid areas of the segments and describe the classification method of data and segment to consider locality of reference for optimizing SSR scheme. We implement U-LFS, which employs our segment space recycling scheme in LFS, and experimental results show that SSR scheme increases performance of WOLF by up to 1.9 times in HDD and 1.6 times in SSD when file system utilization is high.

• Journal of KIISE
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• v.43 no.6
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• pp.627-635
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• 2016

When many processes issue write operations alternately on Log-structured File System (LFS), the created files can be fragmented on the file system layer although LFS sequentially allocates new blocks of each process. Unfortunately, this file fragmentation degrades read performance because it increases the number of block I/Os. Additionally, read-ahead operations which increase the number of data to request at a time exacerbates the performance degradation. In this paper, we suggest a new cleaning method on LFS that minimizes file fragmentation. During a cleaning process of LFS, our method sorts valid data blocks by inode numbers before copying the valid blocks to a new segment. This sorting re-locates fragmented blocks contiguously. Our cleaning method experimentally eliminates 60% of file fragmentation as compared to file fragmentation before cleaning. Consequently, our cleaning method improves sequential read throughput by 21% when read-ahead is applied.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.6
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• pp.46-53
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• 1998

A new method to form the double structured active layers of a-Si/a-SiN$_{x}$ of polycrystalline thin film transistor is proposed and poly-Si TFTs employed double structure active film are fabricated. Nitrogen ions were added to bottom amorphous silicon active film(a-SiN$_{x}$ ) and pure a-Si film deposition on a-SiN$_{x}$ was followed. The XeCl excimer laser was irradiated to crystallize double structure active film. The grain growth of upper a-Si film was also promoted in the double structured active layers of a-Si/a-SiN$_{x}$ due to the mitigation of solidification process of lower a-SiN$_{x}$ layer. Our experimental results show that the ratio of NH$_3$/SiH$_4$ is required to maintain below 0.11 for the reduction of contact resistance of n$^{+}$ poly-SiN$_{x}$ layer.r.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.4
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• pp.309-313
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• 2009

SQL:2003 standard provides SQL/XML publishing functions to publish the result of an SQL query as XML values but it does not provide any SQL/XML publishing function that can publish the result of a recursive query as recursively structured XML values. Therefore, for the relational tuples which are connected directly or indirectly according to given conditions, to publish both the contents of them and the relationship among them as XML values with the use of appropriate SQL/XML publishing functions, we have to write a nested SQL query. Writing that query, however, is not easy provided that the depth of the connections is deep even if we know the depth of them and is not possible once the depth of the connections is not known in advance. In order to resolve that problem, we propose a new SQL function XMLNEST that can publish the result of a recursive query as recursively structured XML values.

• The Journal of the Korea Contents Association
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• v.19 no.1
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• pp.1-15
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• 2019

One of the biggest difficulties in the vocational training field is the dropout problem. A large number of students drop out during the training process, which hampers the waste of the state budget and the improvement of the youth employment rate. Previous studies have mainly analyzed the cause of dropouts. The purpose of this study is to propose a machine learning based model that predicts dropout in advance by using various information of learners. In particular, this study aimed to improve the accuracy of the prediction model by taking into consideration not only structured data but also unstructured data. Analysis of unstructured data was performed using Word2vec and Convolutional Neural Network(CNN), which are the most popular text analysis technologies. We could find that application of the proposed model to the actual data of a domestic vocational training institute improved the prediction accuracy by up to 20%. In addition, the support vector machine-based prediction model using both structured and unstructured data showed high prediction accuracy of the latter half of 90%.

• Culinary science and hospitality research
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• v.22 no.1
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• pp.135-140
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• 2016

Food is widely accepted as very important factor in tourists' experiences by researchers. However, few studies revealed tourists' importance of food for their travel. Therefore, through a case study in Busan (South Korea), this study aims to critically assess the importance of food tourism from domestic tourists' perspectives. In particular, this study assess the relationship between food tourists' value, nutrition information, behavioral intention of tourists' food experiences during their travel. Using SmarPLS program, a quantitative research methodology involving a structured questionnaire has been adopted. The results reveal that food tourists' value and importance of nutrition information plays different roles in food tourism. Food tourism value and nutrition information has shown its importance for increasing revisit intention in Busan. In light of these findings, marketing strategies can be identified to accelerate the development of food tourism at a destination.

• Korean Institute of Interior Design Journal
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• no.31
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• pp.71-78
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• 2002

Understanding the consumer changed life styles are integrated, mutual complement for user's worth and consciousness, the life of consumption, etc. Recently, Apartment Model House has built for distribute to Apartment house When they enter the units after 2 or 3 years. So, Interior designer make an inference from the changed life styles. But, We don't have enough information to trace the design trend about residential space design. Design database is correspond with interior space and structured entity relationship. There are three parts in this Database, Type, Elements and Relation information. Type are composed size, ages, style, and space, Elements are materials and space elements. Relation information are publishing, designer, exhibition, construction company, remodeling, Intoner design and User favorite styles are the development in web environment. This research supplies interior design information for Web environment and trend analysis supports collaboration with development of interior design information database.

• Journal of Korean Library and Information Science Society
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• v.26
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• pp.441-478
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• 1997

This paper surveyed the development and future of electronic journals. The growing and impact of electronic publishing, developments and access of electronic journals, and the future of electronic journals were examined in detail, and remaining problems were analyzed. The findings of the study can be summarized as follows : 1. The future of electronic journals is not an issue of technology it is an issue of economics and social policy. And, the cost of delivering an electronic version to end-users were more expensive. 2. More sophisticated markup software and display software system are needed for fully structured text versions of articles. 3. Coordination of effort is essential in order that we maximize the end-users access requirements against resonable protection for the intellecture effort of the scholarly writer. 4. The success of an electronic journals will depend on the improved communication and cooperation between libraries, users, author, publishers, and information technology specialists. The advent of electronic information delivery has brought with it these issues to be solved. And development in the delivery of scholarly information by electronic means will accelerate.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.14
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• pp.373-395
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• 2000

Recently international trade environment has been rapidly changed according to information age. In particular, international trade has been carried out with various ways under the digital revolution. In this regard, the companies are handling their business with the open network internet and doing their critical marketing activities which are very different from the existed trade customs. However, trade-related information database which is necessary to import and export activities is partly built, and there are many issues to be settled down. In other words, electronic trade opportunity website in the field of overseas marketing and customs clearance with EDI(electronic data interchange) are developed, but the database which companies can make use of their businesses is not fully supported. Therefore the structured database should be developed urgently from the stage of opening business to that of payment. This study closely analyzes the databases under the trade procedure, look into the problems of those database and suggest the solutions of trade information databases. Finally this study provides a sort of trade infrastructure for the development of international trade by internet through the building of trade information.

• Annual Conference of KIPS
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• 2001.04b
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• pp.779-782
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• 2001

IHWA 는 분리개발 된 객체 컴포넌트를 통합함으로써 새로운 응용 시스템을 작성할 수 있는 CBSE(Component Based Software Engineering)기법을 바탕으로 한, 웹 기반 정보 저장/검색의 전형적 모델을 제공하는 소프트웨어 시스템이다. 현재 본 연구팀은 IHWA 시스템의 적용 사례로서 e-business 를 위한 쇼핑몰을 구축하고자 검색, 지불, 운용분야의 모듈들을 S/W 컴포넌트로 개발 중에 있다. 본 논문에서는 그 중, IHWA 의 검색분야에서 상품정보를 보다 효율적으로 수집하고 사용자에게 양질의 정보를 제공하기 위해 필수적으로 요구되는 정보 수집 서비스의 구조에 대하여 설명하고, 특히 비 정형화 된 XML 웹 소스에서의 정보수집 방법에 있어 현재 진행중인 연구에 대하여 설명 하고자 한다.