• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.337-352
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• 2023

In general, Rainfall-Runoff model parameter set is optimized using the entire data to calculate unique parameter set. However, Korea has a large precipitation deviation according to the season, and it is expected to even worsen due to climate change. Therefore, the need for hydrological data considering seasonal characteristics. In this study, we conducted regional sensitivity analysis(RSA) using the conceptual Rainfall-Runoff model, GR4J aimed at the Soyanggang dam basin, and clustered combining the RSA results with hydrometeorological data using Self-Organizing map(SOM). In order to consider the climate characteristics in parameter estimation, the data was divided based on clustering, and a calibration approach of the Rainfall-Runoff model was developed by comparing the objective functions of the Global Optimization method. The performance of calibration was evaluated by statistical techniques. As a result, it was confirmed that the model performance during the Cold period(November~April) with a relatively low flow rate was improved. This is expected to improve the performance and predictability of the hydrological model for areas that have a large precipitation deviation such as Monsoon climate.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.3
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• pp.55-64
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• 2014

While utilizing high resolution satellite image for land use classification has been popularized, object-oriented classification has been adapted as an affordable classification method rather than conventional statistical classification. The aim of this study is to extract the paddy field area using object-oriented classification with time series NDVI from high-resolution satellite images, and the RapidEye satellite images of Jaeryung-gun in North Korea were used. For the implementation of object-oriented classification, creating objects by setting of scale and color factors was conducted, then 3 different land use categories including paddy field, forest and water bodies were extracted from the objects applying the variation of time-series NDVI. The unclassified objects which were not involved into the previous extraction classified into 6 categories using unsupervised classification by clustering analysis. Finally, the unsuitable paddy field area were assorted from the topographic factors such as elevation and slope. As the results, about 33.6 % of the total area (32313.1 ha) were classified to the paddy field (10847.9 ha) and 851.0 ha was classified to the unsuitable paddy field based on the topographic factors. The user accuracy of paddy field classification was calculated to 83.3 %, and among those, about 60.0 % of total paddy fields were classified from the time-series NDVI before the unsupervised classification. Other land covers were classified as to upland(5255.2 ha), forest (10961.0 ha), residential area and bare land (3309.6 ha), and lake and river (1784.4 ha) from this object-oriented classification.

• Safety and Health at Work
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• v.7 no.3
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• pp.201-207
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• 2016

Background: Korean Working Conditions Surveys (KWCS), referencing European Working Conditions Surveys, have been conducted three times in order to survey working condition and develop work-related policies. However, we found three limitations for managing the collected KWCS data: (1) there was no computerized system for managing data; (2) statistical KWCS data were provided by limited one-way communication; and (3) the concept of a one-time provision of information was pursued. We suggest a web-based public service system that enables ordinary people to make greater use of the KWCS data, which can be managed constantly in the future. Methods: After considering data characteristics, we designed a database, which was able to have the result of all pairwise combinations with two extracted data to construct an analysis system. Using the data of the social network for each user, the tailored analysis system was developed. This system was developed with three methods: clustering and classification for building a social network, and an infographic method for improving readability through a friendly user interface. Results: We developed a database including one input entity consisting of the sociodemographic characteristics and one output entity consisting of working condition characteristics, such as working pattern and work satisfaction. A web-based public service system to provide tailored contents was completed. Conclusion: This study aimed to present a customized analysis system to use the KWCS data efficiently, provide a large amount of data in a form that can give users a better understanding, and lay the ground for helping researchers and policy makers understand the characteristics.

• Journal of the Korea Society of Computer and Information
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• v.25 no.11
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• pp.201-210
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• 2020

Navy submarines are developed into complex weapons systems with various equipment, which directly leads to difficulties in submarine maintenance. In addition, the method of establishing a maintenance plan for submarines is limited in efficient maintenance because it relies on statistical access to the number of people, number of target ships, and consumption time. For efficient maintenance, it is necessary to derive and maintain major maintenance factors based on an understanding of the target. In this paper, the maintenance loads rate is defined as a key maintenance factor. the submarine maintenance data is analyzed using the SNA scheme to identify phenomena by focusing on the relationship between the analysis targets. Through this, maintenance loads characteristics that have not been previously revealed in quantitative analysis are derived to identify areas that the maintenance manager should focus on.

• Korean Journal of Social Welfare
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• v.59 no.2
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• pp.143-169
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• 2007

The major purpose of this study was to offer a comprehensive analysis of the changing trends and causes of poverty among urban wage earners' households from 1995 to 2005. In order to do that, this study used the micro data of "Income and Expenditure Survey of Urban Households" by the National Statistical Office(NSO) and GEE(Generalized estimating equation) regression model which is know as an appropriate method for the longitudinal and clustering data. The results show that (1) the numbers of poverty rate and poverty gap in recent years are even getting seriously worse than those in the IMF crisis. (2) Main characteristics of poor are female headed, old aged, low educated households, and having atypical working position. (3) Major determinants of poverty are also related to the variables as mentioned the above. (4) However, poverty reduction effect of public transfer increased preferably in recent years.

• The Korean Journal of Applied Statistics
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• v.33 no.5
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• pp.591-601
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• 2020

The self-organizing map (SOM) is a unsupervised learning method projecting high-dimensional data into low-dimensional nodes. It can visualize data in 2 or 3 dimensional space using the nodes and it is available to explore characteristics of data through the nodes. To understand the structure of data, cluster analysis is often used for nodes obtained from SOM. In cluster analysis, the optimal number of clusters is one of important issues. To help to determine it, various cluster validity indexes have been developed and they can be applied to clustering outcomes for nodes from SOM. However, while SOM has an advantage in that it reflects the topological properties of original data in the low-dimensional space, these indexes do not consider it. Thus, we propose a new cluster validity index for SOM based on connectivity between nodes which considers topological properties of data. The performance of the proposed index is evaluated through simulations and it is compared with various existing cluster validity indexes.

• Journal of Information Management
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• v.18 no.4
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• pp.98-117
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• 1985

At the present time, the role and importance of information retrieval has greatly increased for two main reasons: the coverage of the searchable collections is now extensive and collection size may exceed several million documents; further more, the search results can now be obtained more or less instantaneously using online procedures and computer terminal devices that provide interaction and communication between system and users. The large collection size make it plausible to the users that relevant information will in fact be retrieved as a result of a search operation, and the probability of obtaining the search output without delay creates a substantial user demand for the retrieval services.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.2
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• pp.44-51
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• 2009

Text understand in natural images has become an active research field in the past few decades. In this paper, we present an automatic recognition system in Korean signboards with a complex background. The proposed algorithm includes detection, binarization and extraction of text for the recognition of shop names. First, we utilize an elaborate detection algorithm to detect possible text region based on edge histogram of vertical and horizontal direction. And detected text region is segmented by clustering method. Second, the text is divided into individual characters based on connected components whose center of mass lie below the center line, which are recognized by using a minimum distance classifier. A shape-based statistical feature is adopted, which is adequate for Korean character recognition. The system has been implemented in a mobile phone and is demonstrated to show acceptable performance.

• Parasites, Hosts and Diseases
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• v.29 no.1
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• pp.55-66
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• 1991

A numerical taxonomy was studied on a group of heterophyid trematodes and analysis was made on the following species: Metagonimus yokogawai (3 OTU, Operational Taxonomic Unit) , Metagcnimus Miyata Type (3 OTU), Metagonimus takahashii (2 OTU), Heterophyes dispar (2 OTU), Heterephyes heterophyes (1 OTU), Heterophyes nocens (2 OTV), Heterophyopsis continua (1 OTU), Pygidiopsis summa (3 OTU), Stellantchasmus falcatus (2 OTU) and Stictodora sari (2 OTU). Twenty-six morphological characters were measured and their values were expressed as relative ratios. Similarity and correlation matrix among each individuals were calculated. Clustering analysis by Ward's method and factor analysis were performed using the SAS (Statistical Analysis System) package. As a results, the groups belonging to the genus of Metegenimus were divided into three phonons (Awetegonimus yokogawai, Metegcnimus Miyata Type, M. takahashii) , and Metagonimus Miyata Type was classified as the level of subspecies of M. takahashii. The groups belonging to the genus Heterophyes were clearly divided into three phonons (Heterophyes dispar, H. heterephyes, H. nocens), and H. nccens was classified as not a subspecies level of H. heterophyes but a distinct species. Other species were classified as distinct phonons. From these results, the appllcr lion of numerical taxonomy on trematode classification is considered to be a great aid to determine the limit of taxa.

• Convergence Security Journal
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• v.19 no.2
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• pp.3-9
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• 2019

Most of security countermeasures have been implemented to cope with continuous increase leakage of technology, but almost security countermeasures are focused on securing the boundary between inside and outside. This is effective for detecting and responding to attacks from the outside, but it is vulnerable to internal security incidents. In order to prevent internal leakage effectively, this study identifies activities corresponding to technology leakage activities and designes technology leakage activity detection items. As a design method, we analyzed the existing technology leakage detection methods based on the previous research and analyzed the technology leakage cases from the viewpoint of technology leakage activities. Through the statistical analysis, the items of detection of the technology leakage outcomes were verified to be appropriate, valid and reliable. Based on the results of this study, it is expected that it will be a basis for designing the technology leaking scenarios based on future research and leaking experiences.