• Journal of Korean Society of Transportation
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• v.5 no.1
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• pp.59-74
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• 1987

A prediction is an indispensable element to research of Social Science, especially in Regional planning, City planning, and Transportation planning. Since 1930s, varieties of prediction methods have been developed. In the 1980s, numerical models have been used by high-developed computers. even though the numerical models can be figured mathematically, it could not be applied practically due to it's expertness and complicateness. And even professional planners often can not use their ideas which are valuable experiences in prediction process, because they are not knowledgable for numerical models. The YSIM developed by author, is available as follows. i)Numerical modeling of professional experiences ii)Providing a foundation of large-scale model iii) Understanding of research object structure The YSIM make use of matrix to identify the system structure which is similar to the Cross Impact Method. To evaluated the YSIM availabilities, it is compared with the early developed methodologies such as KSIM, QSIM, and SPIN. As the result, it was confirmed that YSIM was more accurate in the prediction. The algorithms in YSIM is programmed for use of PCs.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.10
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• pp.616-623
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• 2003

Competition among electric generation companies is a major goal of restructuring in the electricity industry, The trading system in an electricity market has been one of the most important issues in deregulated electricity market. This paper deals with comparisons of the major two types of the trading system: compulsory pool market and bilateral contract market. The two trading systems are compared quantitatively from the viewpoint of consumer's surplus and social welfare, This paper, also, proposes a unified model of Cournot and Bertrand for analyzing the mixed trading system of pool market and bilateral contract market. Nash equilibrium of the unified model is derived by criteria for participating in bilateral contract market. Numerical results from a sample case show that a mixed trading system of pool market and price-competitive bilateral market is beneficial to consumer from the view points of consumer's surplus.

• The Korean Journal of Applied Statistics
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• v.25 no.4
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• pp.613-620
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• 2012

In most cases of multidimensional scaling(MDS), the distances or dissimilarities among units are assumed to be symmetric. Thus, it is not an easy task to deal with asymmetric distances. Asymmetric MDS developed so far face difficulties in the interpretation of results. This study proposes a much simpler asymmetric MDS, that utilizes the notion of "altitude". The analogy arises in mountaineering: It is easier (more difficult) to move from the higher (lower) point to the lower (higher). The idea is formulated as a quantification problem, in which the disparity of distances is maximally related to the altitude difference. The proposed method is demonstrated in three examples, in which the altitudes are visualized by rainbow colors to ease the interpretability of users.

• Communications for Statistical Applications and Methods
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• v.27 no.5
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• pp.569-578
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• 2020

Various graph clustering methods have been introduced to identify communities in social or biological networks. This paper studies the entropy-based and the Markov chain-based methods in clustering the undirected graph. We examine the performance of two clustering methods with conventional methods based on quality measures of clustering. For the real applications, we collect the mathematical subject classification (MSC) codes of research papers from published mathematical databases and construct the weighted code-to-document matrix for applying graph clustering methods. We pursue to group MSC codes into the same cluster if the corresponding MSC codes appear in many papers simultaneously. We compare the MSC clustering results based on the several assessment measures and conclude that the Markov chain-based method is suitable for clustering the MSC codes.

• Communications for Statistical Applications and Methods
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• v.4 no.3
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• pp.637-644
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• 1997

Sometimes, the first principal component may come logically from the established knowledge and premises. For example, for the high school students' test scores of Korean, English, Mathematics, Social Study, and Science, it is natural to define the first principal component as the average of all subject scores. In such cases, we need to respect both the background knowledge and the data exploration. The aim of this study is to find the remaining components in principal component analysis of multivariate data when the first principal component is defined a priori by the researcher. Moreover, we study related matrix decomposition and their application to the graphical display.

• Environmental and Resource Economics Review
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• v.11 no.1
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• pp.145-184
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• 2002

This paper analyzes the impact of imposing carbon tax on the Seoul economy to reduce Greenhouse Gas(GHG) emission. We construct the social accounting matrix of Seoul, specifying energy and transport sectors which is closely related to air pollution. Then, we formulated the computable general equilibrium (CGE) model of seoul and performed scenario analysis. The main result shows that the economic cost of GHG reduction is quite large but the health benefit is also considerable. It also suggests the importance of cost effective measures such as the development of new energy technology and the improvement of energy efficiency.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2009.11a
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• pp.77-80
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• 2009

Because buildings which apply color that is various to concrete recently are introduced, value as design element of building is rising gradually in townscape. Even if expense is increased according as importance of concrete that have variety of design because do such social background and connection is emphasized, development of color concrete is pressing. Therefore, in this research, examined concrete physical & chemical characteristics by use of acid agent as part of research to embody diverse surface color of cement material. Here, embodiment of various color by unique color that stained hydrate has as that Color Concrete forms stained oxide that react with hydrate within concrete spreading stained agent that contain acid and metallic-ion in matrix that have cement ingredient on the surface is available.

• Journal of Digital Convergence
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• v.1 no.1
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• pp.147-164
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• 2003

The use of electronic mail and messenger software tools has been increased rapidly over a decade. Compared to the variety of research related to the relationship between personal psychological traits and communication modes, effects of human psychology on online activities have only recently become a focus of interest. This research analyzed the relationship between personal psychological type and online connectivity. We employed network analysis methodology and collected and analyzed data from 146 subjects. Significant differences in network measures were found among groups with different psychological style. Findings of the research can provide several implications for managerial activities regarding social connectivity.

• ETRI Journal
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• v.38 no.1
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• pp.52-61
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• 2016

A microblog is a service typically offered by online social networks, such as Twitter and Facebook. From the perspective of information dissemination, we define the concept behind a spreading matrix. A new WeiboRank algorithm for identification of key nodes in microblog networks is proposed, taking into account parameters such as a user's direct appeal, a user's influence region, and a user's global influence power. To investigate how measures for ranking influential users in a network correlate, we compare the relative influence ranks of the top 20 microblog users of a university network. The proposed algorithm is compared with other algorithms - PageRank, Betweeness Centrality, Closeness Centrality, Out-degree - using a new tweets propagation model - the Ignorants-Spreaders-Rejecters model. Comparison results show that key nodes obtained from the WeiboRank algorithm have a wider transmission range and better influence.

• Journal of radiological science and technology
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• v.42 no.4
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• pp.301-308
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• 2019

This study reviewed whether radiology-related pictograms listed on the website of hospitals deliver clearly, accurately and quickly the necessary information. TOPSIS was carried out to select the most fitting pictograms for the department of radiology, department of radiation oncology, and department of nuclear medicine. The finally selected pictogram for the department of radiology shows an image of the chest (lungs), while that for the department of radiation oncology shows the process of treatment using equipment. Using these pictograms as standards seem to be appropriate to a certain level. However, the pictogram for department of nuclear medicine has a symbol for a nucleus and is thus inappropriate to meet the standards for a hospital pictogram. This study is meaningful in that it has established evaluation methods and procedures relaetd to radiation pictograms.