• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.1
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• pp.21-40
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• 2018

In this paper, we propose the distributed robust beamforming design scheme in cognitive two-way amplify-and-forward (AF) relay networks with imperfect channel state information (CSI). Assuming the CSI errors follow a complex Gaussian distribution, the objective of this paper is to design the robust beamformer which minimizes the total transmit power of the collaborative relays. This design will guarantee the outage probability of signal-to-interference-plus-noise ratio (SINR) beyond a target level at each secondary user (SU), and satisfies the outage probability of interference generated on the primary user (PU) above the predetermined maximum tolerable interference power. Due to the multiple CSI uncertainties in the two-way transmission, the probabilistic constrained optimization problem is intractable and difficult to obtain a closed-form solution. To deal with this, we reformulate the problem to the standard form through a series of matrix transformations. We then accomplish the problem by using the probabilistic approach based on two sorts of Bernstein-type inequalities and the worst-case approach based on S-Procedure. The simulation results indicate that the robust beamforming designs based on the probabilistic method and the worst-case method are both robust to the CSI errors. Meanwhile, the probabilistic method can provide higher feasibility rate and consumes less power.

• Korean Journal of Computational Design and Engineering
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• v.10 no.6
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• pp.444-454
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• 2005

Recently, the requirements of multi-resolution models of a solid model, which represent an object at multiple levels of feature detail, are increasing for engineering tasks such as analysis, network-based collaborative design, and virtual prototyping and manufacturing. The research on this area has focused on several topics: topological frameworks for representing multi-resolution solid models, criteria for the level of detail (LOD), and generation of valid models after rearrangement of features. As a solution to the feature rearrangement problem, the new concept of the effective zone of a feature is introduced in the former part of the paper. In this paper, we propose a feature-based non-manifold modeling system to provide multi-resolution models of a feature-based solid or non-manifold model on the basis of the effective feature zones. To facilitate the implementation, we introduce the class of the multi-resolution feature whose attributes contain all necessary information to build a multi-resolution solid model and extract LOD models from it. In addition, two methods are introduced to accelerate the extraction of LOD models from the multi-resolution modeling database: the one is using an NMT model, known as a merged set, to represent multi-resolution models, and the other is storing differences between adjacent LOD models to accelerate the transition to the other LOD. We also suggest the volume of the feature, regardless of feature type, as a criterion for the LOD. This criterion can be used in a wide range of applications, since there is no distinction between additive and subtractive features unlike the previous method.

• The KIPS Transactions:PartA
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• v.9A no.1
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• pp.29-36
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• 2002

For the efficient collaboration awareness, the CSCW (Computer-Supported Cooperative Work) systems provide functions such as telepointing, snap-shot, and document/project tracking. Among these, telepointing allows an event occurrence on the shared window of a local computing system to be presented in remote computing systems. Although telepointing has been mentioned in the literature, few research papers deal with the functional requirements and protocols for telepointing. This parer describes the functional requirements and payload format for RTP (Real-Time Transport Protocol)-based telepointing. In order to evaluate the performance of the proposed RTP-barred telepointing, we have implemented a whiteboard and compared it with that of the Microsoft Netmeeting. The evaluation results show that the proposed telepointing performs better in terms of CPU usage and the amount of network traffic.

• The Journal of the Convergence on Culture Technology
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• v.9 no.5
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• pp.951-956
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• 2023

In the current situation where systematic and active disaster management is becoming more important, domestic libraries do not have their own disaster management plans or support systems. In order to improve these problems, this study looked at overseas cases. Among them, we looked at Japan, where related cases and research are actively underway due to its exposure to various geopolitical disasters. In particular, we focused on cases of public-private cooperation established after the Great East Japan Earthquake. Association's Library Disaster Response Committee and saveMALK, a voluntary network of experts. The Library Disaster Response Committee played a central role in organizing donations and volunteer activities, and saveMALK played a role in collecting and sharing information by forming a collective intelligence among relevant experts. This analysis of the Japanese case has positive implications for building collaborative disaster management system.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.34 no.3
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• pp.135-161
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• 2023

This study analyzed the research trends of COVID-19 research papers published in medical journals of Korea. Data were collected from 25 MEDLINE journals in 'Medicine and Pharmacy' studies and a total of 800 were selected. As a result of the study, authors from domestic affiliations made up 76.96% of the total, and the proportion of authors from foreign institutions decreased without significant change. The authors' majors were 'Internal Medicine' (32.85%), 'Preventive Medicine/Occupational and Environmental Medicine' (16.23%), 'Radiology' (5.74%), and 'Pediatrics' (5.50%), and 435 (54.38%) papers were collaborative research. As for author keywords, 'COVID19' (674), 'SARSCoV2' (245), 'Coronavirus' (81), and 'Vaccine' (80) were derived as top keywords. There were six words that appeared throughout the entire period: 'COVID19,' 'SARSCoV2,' 'Coronavirus,' 'Korea,' 'Pandemic,' and 'Mortality.' Co-occurrence network analysis was conducted on MeSH terms and author keywords, and common keywords such as 'covid-19,' 'sars-cov-2,' and 'public health' were derived. In topic modeling, five topics were identified, including 'Vaccination,' 'COVID-19 outbreak status,' 'Omicron variant,' 'Mental health, control measures,' and 'Transmission and control in Korea.' Through this study, it was possible to identify the research areas and major keywords by year of COVID-19 research papers published during the 'Public Health Emergency of International Concern (PHEIC).'

• Journal of Intelligence and Information Systems
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• v.26 no.4
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• pp.67-86
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• 2020

Recommender Systems have been huge influence users and business more and more. Recently the importance of E-commerce has been reached rapid growth greatly in world-wide COVID-19 pandemic. Recommender system is the center of E-commerce lively. Top ranked E-commerce managers mentioned that recommender systems have a major influence on customer's purchase such as about 50% of Netflix, Amazon sales from their recommender systems. Most algorithms have been focused on improving accuracy of recommender system regardless of novelty, diversity, serendipity etc. Recommender systems with only high accuracy cannot satisfy business long-term profit because of generating sales polarization. In addition, customers do not experience enjoyment of shopping from only focusing accuracy recommender system because customer's preference is changed constantly. Therefore, recommender systems with various values need to be developed for user's high satisfaction. Reranking is the most useful methodology to realize diversity of recommender system. In this paper, diversity of recommender system is represented through constructing high similarity with users who have different preference using each user's purchased item's category algorithm. It is distinguished from past research approach which is changing the algorithm of recommender system without user's diversity preference level. We tried to discover user's diversity preference level and observed the results how the effect was different according to user's diversity preference level. In addition, graph-based recommender system was used to show diversity through user's network, not collaborative filtering. In this paper, Amazon Grocery and Gourmet Food data was used because the low-involvement product, such as habitual product, foods, low-priced goods etc., had high probability to show customer's diversity. First, a bipartite graph with users and items simultaneously is constructed to make graph-based recommender system. However, each users and items unipartite graph also need to be established to show diversity of recommender system. The weight of each unipartite graph has played crucial role changing Jaccard Distance of item's category. We can observe two important results from the user's unipartite network. First, the user's diversity preference level is observed from the network and second, dissimilar users can be discovered in the user's network. Through the research process, diversity of recommender system is presented highly with small accuracy loss and optimalization for higher accuracy is possible controlling diversity ratio. This paper has three important theoretical points. First, this research expands recommender system research for user's satisfaction with various values. Second, the graph-based recommender system is developed newly. Third, the evaluation indicator of diversity is made for diversity. In addition, recommender systems are useful for corporate profit practically and this paper has contribution on business closely. Above all, business long-term profit can be improved using recommender system with diversity and the recommender system can provide right service according to user's diversity level. Lastly, the corporate selling low-involvement products have great effect based on the results.

• Journal of the Korean Society for information Management
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• v.33 no.2
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• pp.177-200
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• 2016

The purpose of this study was to analyze how the Library and Information Science (LIS) related research efforts in Korea contributed to the progress of the Human Computer Interaction (HCI) discipline to identify the potential collaboration research partners and topics. The following data was used for the network and frequency analysis: titles, keywords and affiliation information extracted from the Korean journals serving the LIS fields as well as the conference proceedings of the Korean HCI society. Information communication technology, computer engineering, and technology industry had been active in research collaborations but LIS field was comparatively not active. This study was able to determine that LIS researchers carried out important research but they had not much interests in the topics that required interdisciplinary collaboration. However, there were a number of papers, which were not authored by LIS discipline researchers, in the LIS related journals. In addition, there are a few ongoing interdisciplinary research projects which included LIS researchers. This reveals that it is possible for the LIS field could play an important role in the future if the researchers actively participate the collaborative projects.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.926-932
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• 2009

Recently many research reports on effective use of mobile devices for museums to provide information on displayed artifacts providing individualized learning space, collaborative learning, and discovery learning, Such devices have many possibilities to support learning as a participatory media and social network. Mobile devices are used, however, limited for its usability and lack in providing expected learning experiences. It offers one-way interaction and they are often limited in providing customized services for different patrons to experience learning and entertainment. In this research, we have adopted user centered design approach to identify the needs and possible usage of PDA system in the museum. Research methods include contextual observation and inquiry with symbolic interactionism for qualitative research and its epistemology. We have developed conceptual model with scenario and storyboard method, and developed vertical prototype with Flash.

• Land and Housing Review
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• v.12 no.2
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• pp.61-78
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• 2021

This study aims to understand the thematic trends globally developed in the 'Green Urbanism' related research. Research methodology is based on systemic review of international literature published for the past 20 years period between 2000 and 2020. The specific methods applied include not only literature search by citation, co-authorship, and co-occurrence but social network analysis in order to find correlations among the publication. The correlations are visualized and analysed using VOSviewer and Ucinet software. The analysis indicates that total of 51 studies were carried out by 89 authors from 54 institutions across 21 countries during the period. The majority of the research was done by a country-specific study and only a few research were collaborative studies with other countries. The most common theme that occurred in the early years was 'sustainability and the theme evolved toward specific ones such as 'built environment', 'infrastructure', and 'health'. Having considered that climate change has become a global challenge, green urbanism is expected to be a future direction to pursue environmentally sustainable urban spaces. This study also implies that governance, policy support, and intervention are crucial factors in developing sustainable urban spaces.

• Journal of Korean Library and Information Science Society
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• v.50 no.4
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• pp.339-358
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• 2019

The purpose of this study is to understand the topics of the research for the establishment of cooperative platform between libraries, archives, and museums that carry out the common task of providing knowledge information in a broad sense. To achieve the purpose of this study, 637 bibliographic information on three institutions were collected from the Web version of Scopus database. Among the collected bibliographic information, 5,218 words were extracted through NetMiner V.4 and analysed topic modeling. The results are as follows: First, as a result of analyzing the frequency of word appearance according to the tf-idf weight 'Preservation' was the most hottest topic. Second, the topic modeling analysis through LDA(Latent Dirichlet Allocation) algorithm resulted in 13 topic areas. Third, as a result of expressing 13 topic areas as a network, repository construction was the central topic, and the research topics such as cooperation among institutions, conservation environment for collections, system and policy discovery, life cycle of collections, exhibition of information resources, and information retrieval were closely related to the central topic. Fourth, the trend of 13 topic areas by year 1998 is limited to the specific subjects such as system and policy discovery, information retrieval, and life cycle of collections, while the subsequent studies have been carried out after that year.