• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.3
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• pp.217-222
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• 2015

Clustering is one of important data mining techniques known as exploratory data analysis and is being applied in various engineering and scientific fields such as pattern recognition, remote sensing, and so on. The method organizes data by abstracting underlying structure either as a grouping of individuals or as a hierarchy of groups. Weather radar observes atmospheric objects by utilizing reflected signals and stores observed data in corresponding coordinate. To analyze the radar data, it is needed to be separately organized precipitation and non-precipitation echo based on similarities. Thus, this paper studies to apply clustering method to radar data. In addition, in order to solve the problem when precipitation echo locates close to non-precipitation echo, fuzzy logic based clustering method which can consider both distance and other properties such as reflectivity and Doppler velocity is suggested in this paper. By using actual cases, the suggested clustering method derives better results than previous method in near-located precipitation and non-precipitation echo case.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.718-723
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• 2008

Bearing is one of the important mechanical elements used in various industrial equipments. Most of failures occurred during the equipment operation result from bearing defects and breakages. Therefore, monitoring of bearings is essential in preventing equipment breakdowns and reducing unexpected loss. The purpose of this paper is to present an online monitoring method to predict bearing states using vibration signals. Bearing vibrations, which are collected as a form of profile signal, are first analyzed by a discrete wavelet transform. Next, some statistical features are obtained from the resultant wavelet coefficients. In order to select significant ones among them, analysis of variance (ANOVA) is employed in this paper. Statistical features screened in this way are used as input variables to support vector machine (SVM). An hierarchical SVM tree is proposed for dealing with multi-class problems. The result of numerical experiments shows that the proposed SVM tree has a competent performance for classifying bearing fault states.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.76-76
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• 2013

The current hierarchical model of galaxy formation predicts that galaxy halos contain merger relics in the form of long stellar streams. In order to find stellar substructures in galaxy, we focused our investigation on the stellar spatial density around globular clusters and on the quantitative properties of the evolved sequences in the color-magnitude diagrams (CMDs). First, we investigated the spatial configuration of stars around five metal-poor globular clusters in halo region (M15, M30, M53, NGC 5053, and NGC 5466) and one metal-poor globular cluster in bulge region (NGC 6626). Our findings indicate that all of these globular clusters show strong evidence of extratidal features in the form of extended tidal tails around the clusters. The orientations of the extratidal features show the signatures of tidal tails tracing the clusters' orbits and the effects of dynamical interactions with the galaxy. These features were also confirmed by the radial surface density profiles and azimuthal number density profiles. Our results suggest that these six globular clusters are potentially associated with the satellite galaxies merged into the Milky Way. Second, we derived the morphological parameters of the red giant branch (RGB) from the near-infrared CMDs of 12 metal-poor globular clusters in the Galactic bulge. The photometric RGB shape indices such as colors at fixed magnitudes, magnitudes at fixed colors, and the RGB slope were measured for each cluster. The magnitudes of the RGB bump and tip were also estimated. The derived RGB parameters were used to examine the overall behavior of the RGB morphology as a function of cluster metallicity. The behavior of the RGB shape parameters was also compared with the previous observational calibration relation and theoretical predictions of the Yonsei-Yale isochrones. Our results of studies for stellar spatial distribution around globular clusters and the morphological properties of RGB stars in globular clusters could add further observational evidence of merging scenario of galaxy formation.

• Fire Science and Engineering
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• v.32 no.2
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• pp.92-101
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• 2018

This study investigated the impact of post-traumatic stress of the fire-fighting officers who are exposed to traumatic events repeatedly on suicide and attempted to verify the moderating effect of cognitive emotion regulation in the relationship between post-traumatic stress and suicidal ideation. For this investigation, this study measured Post-traumatic stress Diagnostic Scale, Korean Beck scale for Suicidal Ideation, Cognitive Emotion Regulation Questionnaire. The research results are as follows. First, Post-traumatic stress, suicidal ideation, adaptive cognitive emotion regulation, and maladaptive cognitive emotion regulation were correlated. second, A hierarchical regression analysis was conducted in order to examine the moderating effect of cognitive emotion regulation in the relationship between post-traumatic stress and suicidal ideation, and as a result, it was found that a sub-factor of cognitive emotion regulation, adaptive cognitive emotion regulation had a moderating effect in a group of persons with low post-traumatic stress, while maladaptive cognitive emotion regulation had a moderating effect in a group of persons with high post-traumatic stress. These results, this study discussed the necessity of follow-up studies, in addition to its academic and clinical implications.

• Journal of Preventive Medicine and Public Health
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• v.46 no.6
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• pp.300-308
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• 2013

Objectives: The purpose of this study was to classify determinants of cost increases into two categories, negotiable factors and non-negotiable factors, in order to identify the determinants of health care expenditure increases and to clarify the contribution of associated factors selected based on a literature review. Methods: The data in this analysis was from the statistical yearbooks of National Health Insurance Service, the Economic Index from Statistics Korea and regional statistical yearbooks. The unit of analysis was the annual growth rate of variables of 16 cities and provinces from 2003 to 2010. First, multiple regression was used to identify the determinants of health care expenditures. We then used hierarchical multiple regression to calculate the contribution of associated factors. The changes of coefficients ($R^2$) of predictors, which were entered into this analysis step by step based on the empirical evidence of the investigator could explain the contribution of predictors to increased medical cost. Results: Health spending was mainly associated with the proportion of the elderly population, but the Medicare Economic Index (MEI) showed an inverse association. The contribution of predictors was as follows: the proportion of elderly in the population (22.4%), gross domestic product (GDP) per capita (4.5%), MEI (-12%), and other predictors (less than 1%). Conclusions: As Baby Boomers enter retirement, an increasing proportion of the population aged 65 and over and the GDP will continue to increase, thus accelerating the inflation of health care expenditures and precipitating a crisis in the health insurance system. Policy makers should consider providing comprehensive health services by an accountable care organization to achieve cost savings while ensuring high-quality care.

• Journal of Korean Society of Rural Planning
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• v.16 no.3
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• pp.43-49
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• 2010

This study generalized and systemized the unit-project items of 176 project districts for the rural village comprehensive development projects (RVCDP). This paper surveyed opinions of III answerers (7 specialists, 43 agents of Korea Rural Community corporation, and 61 agents of local government of cities and counties) in order to determine the classification system and their corresponding weighting values of the project items using analytic hierarchy process (AHP) method. From the results extracted by project plans of 176 project districts for 5 years from 2004 to 2008, this study decided a hierarchical system for unit-project items of RVCDP by AHP method, which consisted of three steps: 4 items for 1st step, 13 items for 2nd step, and 52 items for 3rd step. The first step contains 4 items of Strength of Rural-urban Exchange & Regional Capability (RURC), Green-income Infrastructure & Facility (GIF), Culture-health-welfare Facility, and Eco-environment & Landscape facility (ELF). In the survey of weighting values with AHP method, the analysis result for the first step showed that in opinion of specialists, GIF is more important than the others while in opinion of the other agents, RURC is more important. In the second step, Product Facility is more important in the specialists, whereas Strength of Resident Capability is the most important in the other agents. Analyzed unit project items as the third step, all answerers evaluated that the Education and Excursion for Rural Resident Capability has the highest weighting values.

• The Journal of the Korea Contents Association
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• v.11 no.7
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• pp.366-373
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• 2011

This study aims to present basic directions and implications of the organizational culture and job performance by analysis of the causal path between the variables acknowledging the important role of the organizational satisfaction on the assumption that the organizational culture which is developed for improvement of the revenue officer's job performance by the taxation organization. In the results of analysis, the clan culture, hierarchy culture and market culture except the culture of innovation have positive effects on the organizational satisfaction, and the higher the organizational satisfaction, the higher efficiency of the performance of the tax administration affairs become, so the job performance becomes increase. This can be the results that the characteristics of the tax organizational culture which conducts the taxation administration affairs by the clan culture which is hierarchical and emphasizes the business performance through teamwork, and the market culture which emphasizes the results reflect the job performance. Therefore, the organizational culture that develops sense of ownership and being performed autonomously and responsibly should be created in order to increase the competitiveness in the organizations and to increase the job performance efficiently by the members of the organization to have worthwhile feeling.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.11-14
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• 2009

In this paper, we propose the method configuring social networks among users based on users' context and profile. Recently, many researchers are concerned about social networks related with collaborative systems. In case of the existing researches, however, it is difficult to configure social networks dynamically because they are based on static data types, such as log and profile of users. The proposed method uses not only user profiles but also context reflecting users' behavior dynamically. It computes the similarity among users' behavior contexts using hierarchical structure of context domain knowledge model. And it calculates relationships between contexts by given weight factors of category of context model. In order to verify usefulness of the method, we conduct an experiment on configuring social network according to change of user context. We expect that it makes dynamic analysis of relationship of users possible.

• Journal of KIISE
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• v.41 no.12
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• pp.1035-1049
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• 2014

This paper presents a new method to detect attack patterns in security-critical systems, based on a new notion of Behavior Ontology. Generally security-critical systems are large and complex, and they are subject to be attacked in every possible way. Therefore it is very complicated to detect various attacks through a semantic structure designed to detect such attacks. This paper handles the complication with Behavior Ontology, where patterns of attacks in the systems are defined as a sequences of actions on the class ontology of the systems. We define the patterns of attacks as sequences of actions, and the attack patterns can then be abstracted in a hierarchical order, forming a lattice, based on the inclusion relations. Once the behavior ontology for the attack patterns is defined, the attacks in the target systems can be detected both semantically and hierarchically in the ontology structure. When compared to other attack models, the behavior ontology analysis proposed in this paper is found to be very effective and efficient in terms of time and space.

• Journal of KIISE
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• v.44 no.1
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• pp.21-26
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• 2017

In recent years, new technologies such as Internet of Things, Cloud Computing and Big Data are being widely used. And the type and amount of data is dramatically increasing. This makes security an important issue. In terms of leakage of sensitive personal information. In order to protect confidential information, a method called anonymization is used to remove personal identification elements or to substitute the data to some symbols before distributing and sharing the data. However, the existing method performs anonymization by generalizing the level of quasi-identifier hierarchical. It requires a higher level of generalization in case where k-anonymity is not satisfied since records in data table are either added or removed. Loss of information is inevitable from the process, which is one of the factors hindering the utility of data. In this paper, we propose a novel anonymization technique using decision tree based machine learning to improve the utility of data by minimizing the loss of information.