• Communications for Statistical Applications and Methods
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• v.22 no.5
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• pp.415-434
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• 2015

In this paper we overview the literature on common features analysis of economic time series. Starting from the seminal contributions by Engle and Kozicki (1993) and Vahid and Engle (1993), we present and discuss the various notions that have been proposed to detect and model common cyclical features in macroeconometrics. In particular, we analyze in details the link between common cyclical features and the reduced-rank regression model. We also illustrate similarities and differences between the common features methodology and other popular types of multivariate time series modelling. Finally, we discuss some recent developments in this area, such as the implications of common features for univariate time series models and the analysis of common autocorrelation in medium-large dimensional systems.

• Journal of Internet Computing and Services
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• v.16 no.3
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• pp.71-77
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• 2015

This paper implements an estimated closeness centrality ranking algorithm in large-scale workflow-supported social networks and performance analyzes of the algorithm. Existing algorithm has a time complexity problem which is increasing performance time by network size. This problem also causes ranking process in large-scale workflow-supported social networks. To solve such problems, this paper conducts comparison analysis on the existing algorithm and estimated results by applying estimated-driven RankCCWSSN(Rank Closeness Centrality Workflow-supported Social Network). The RankCCWSSN algorithm proved its time-efficiency in a procedure about 50% decrease.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.52 no.7
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• pp.401-406
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• 2003

Electric power industries in several countries are currently undergoing major changes, mainly represented by the privatizations of the power plants and distribution systems. Reliable operations of the power plants directly contribute to the revenue increases of the generation companies in such competitive environments. Strategic optimizations should be performed between the levels of the reliabilities to be maintained and the various preventive maintenance costs, which require the accurate estimations of the power plant reliabilities. However, accurate estimations of the power plant reliabilities are often limited by the lack of accurate power plant failure data. A power plant is not supposed to be failed that often. And if it fails, its impact upon the power system stability is quite substantial in most cases, setting aside the significant revenue losses and lowered company images. Reliability assessment is also important for Independent System Operators(ISO) or Market Operators to properly assess the level of needed compensations for the installed capacity based on the availability of the generation plants. In this paper, we present a power plant reliability estimation technique that can be applied when the failure data is insufficient. Median rank and Weibull distribution are used to accommodate such insufficiency. The Median rank is utilized to derive the cumulative failure probability for each ordered failure. The Weibull distribution is used because of its flexibility of accommodating several different distribution types based on the shape parameter values. The proposed method is applied to small size failure data and its application potential is demonstrated.

• Korea Trade Review
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• v.47 no.3
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• pp.75-92
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• 2022

This study aims to analyze the International trade network of Water transport service using Social Network Analysis for defining the status of Korean Water transport industry. This study use World Input-Output Table of Asian Development Bank from 2000 to 2020 and build the International trade matrix of Water transport service from that. Therefore, this study analyze Out-degree centrality, In-degree centrality and betweenness centrality of Korea and other main countries in the matrix of World Water transport industry. As a result, Korea rank above 10th in the all centralities and the total output also rank 8th in the world, therefore, this study show the importance of Korean Water transport industry in the world. However, Singapore has the highest centrality in the world, even though China has the largest Total output among 63 countries.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.1
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• pp.1-9
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• 2024

Multivariate Quadratic (MQ)-based digital signature schemes have advantages such as ease of implementation and small signature sizes, making them promising candidates for post-quantum cryptography. To enhance the efficiency of such MQ-based digital signature schemes, utilizing sparse matrices have been proposed, including HiMQ, which has been standardized by Korean Telecommunications Technology Association standard. However, HiMQ shares a similar key structure with Rainbow, which is a representative MQ-based digital signature scheme and was broken by the MinRank attack proposed in 2022. While HiMQ was standardized by a TTA and recommended parameters were provided, these parameters were based on cryptanalysis as of 2020, without considering recent attacks. In this paper, we examine attacks applicable to MQ-based digital signatures, specifically targeting HiMQ, and perform a security analysis. The most effective attack against HiMQ is the combined attack, an improved version of the MinRank attack proposed in 2022, and none of the three recommended parameters satisfy the desired security strength. Furthermore, HiMQ-128 and HiMQ-160 do not meet the minimum security strength requirement of 128-bit security level.

• Journal of the Korean Solar Energy Society
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• v.33 no.4
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• pp.101-110
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• 2013

The propose of this study is to understand the phenomenon of radiation and comparison of analysis of two methods. One is analysis method of same-time data and the another is analysis method of rank data. We confirmed that two methods of correlation analysis had the effectiveness and suitability. The followings are main results from this study. 1) The seasonal correlation coefficient of long and short-wave radiation is higher in winter than in summer because of high humidity in the summer season can makes easily cloud in the sky locally. 2) According to analysis method, there is big difference in correlation coefficient from 0.494(Analysis method of same-time data) to 0.967(Analysis method of rank data) with short-wave radiation by the location during summer. These results have significant value in solar radiation research and analysis. It has explored a new way for solar radiation research of analysis method as well.

• Journal of the Korea Society of Computer and Information
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• v.10 no.1 s.33
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• pp.59-66
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• 2005

The organization of the web is progressively more being used to improve search and analysis of information on the web as a large collection of heterogeneous documents. Most people begin at a Web search engine to find information. but the user's pertinent search results are often greatly diluted by irrelevant data or sometimes appear on target but still mislead the user in an unwanted direction. One of the intentional, sometimes vicious manipulations of Web databases is a intentionally biased web page like Google bombing that is based on the PageRank algorithm. one of many Web structuring techniques. In this thesis, we regard the World Wide Web as a directed labeled graph that Web pages represent nodes and link edges. In the Present work, we define the label of an edge as having a link context and a similarity measure between link context and target page. With this similarity, we can modify the transition matrix of the PageRank algorithm. By suggesting a motivating example, it is explained how our proposed algorithm can filter the Web intentionally biased web Pages effective about $60\%% rather than the conventional PageRank.

• Korean Journal of Community Nutrition
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• v.20 no.1
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• pp.53-60
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• 2015

Objectives: The purpose of this study is to provide the basic data for efficient operation and management of the military foodservice by analyzing the satisfaction of the quality of the foodservice and the perception of the military foodservice which are provided according to the ranks of the soldiers. Methods: A total of 252 military personnel (48 Private, 87 Private first class, 74 Corporal and 43 Sergeant) participated in Gyeonggi area from November 1 to 30, 2013, and data were analyzed by the SPSS Win (ver 18.0). Results: The perception with foodservice, variety of menu (p < 0.001), importance (p < 0.01), problem (p < 0.05) and leftover reason (p < 0.05) significantly differed by the rank of the soldiers. With regard to the satisfaction with food, there were significant difference by rank for all items (p < 0.01). Satisfaction with facilities did not indicate significant differences by rank. Satisfaction with sanitation indicated significant difference by rank in the categories of table ware (p < 0.05), process of distribution (p < 0.05), employee's uniform (p < 0.001) and drinking water (p < 0.05). Satisfaction with service indicated significant difference by rank with regard to kindness of employees (p < 0.01), providing information on foodservice (p < 0.05) and fast distribution (p < 0.01). Conclusions: In order to improve the satisfaction of all ranks, there is a need to offer a variety of nutritionally balanced menu and a proper amount of food provided through the voluntary food distribution services. The results also suggested the need to find a sustainable foodservice management plan to carry out satisfaction surveys regularly in the military foodservice.

• The Research Journal of the Costume Culture
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• v.17 no.3
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• pp.367-382
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• 2009

The aim of the current study was to investigate the impact of store attribute satisfaction on intentions of revisit and recommendation among clothing consumers. The data were collected from 319 consumers through survey and frequency analysis, reliability analysis, factor analysis, and multiple regression analysis were used to obtain results. The findings were as follows: 1. From factor analysis, seven factors were distracted: Fact 1(brand and price), Fact 2(store's facility and environment), Fact 3(product), Fact 4(transportation convenience and access), Fact 5(selling and advertisement), Fact 6(store's atmosphere), and Fact 7(salesman's service). 2. Four factors had statistically significant influence on overall satisfaction of clothing consumers. The most influential factor was Fact 2(store's facility and environment) and Fact 5(selling and advertisement), Fact 1(brand and price), and Fact 4(transportation convenience and access) showed their effects on overall satisfaction in an hierarchical rank-order following Fact 2. 3. Four factors such as Fact 2(store's facility and environment), Fact 1(brand and price), Fact 4(transportation convenience and access) and Fact 5(selling and advertisement) in an hierarchical rank-order from Fact 1 had statistically significant impact on intentions of revisit. 4. Six factors such as Fact 1(brand and price), Fact 2(store's facility and environment), Fact 3(product), Fact 5(selling and advertisement), Fact 6(store's atmosphere), and Fact 7(salesman's service) in an hierarchical rank-order from Fact 1 had statistically significant influence on the intention of recommendation. 5. The results further showed that among seven factors, Fact 1(brand and price), 'Fact 2(store's facility and environment), and Fact 5(selling and advertisement) had impact on both the intention of revisit and the intention of recommendation.

• Journal of Korean Society of Transportation
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• v.35 no.6
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• pp.525-544
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• 2017

With the advent of the big data era, the interest in the development of land using traffic data has increased significantly. However, the current research on traffic big data lingers around organizing or calibrating the data only. In this research, a novel method for discovering the hidden values within the traffic data through data mining is proposed. Considering the fact that traffic data and network structures have similarities, network analysis algorithms are used to find valuable information in the actual traffic volume data. The PageRank and HITS algorithms are then employed to find the centralities. While conventional methods present centralities based on uncomplicated traffic volume data, the proposed method provides more reasonable centrality locations through network analysis. Since the centrality locations that we have found carry detailed spatiotemporal characteristics, such information can be used as an objective basis for making policy decisions.