• Journal of Digital Contents Society
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• v.16 no.3
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• pp.445-455
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• 2015

According as internet and computer technology develops, the amount of information has increased exponentially, arising from a variety of web authoring tools and is a new web standard of appearance and a wide variety of web content accessibility as more convenient for the web are produced very quickly. However, web documents are put out on a variety of topics divided into some blocks where each of the blocks are dealing with a topic unrelated to one another as well as you can not see with contents such as many navigations, simple decorations, advertisements, copyright. Extract only the exact area of the web document body to solve this problem and to meet user requirements, and to study the effective information. Later on, as the reconstruction method, we propose a web search system can be optimized systematically manage documents.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.423-429
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• 2011

Cooperative spectrum sensing is proposed to overcome some problem such as multipath fading and shadowing and to improve spectrum sensing performance. There are different combining methods for cooperative spectrum sensing: hard decision method and soft decision method. In this paper, we analysis the performance of cooperative spectrum sensing with distance based weight that is kind of a soft decision rule for cognitive radio(CR) systems and CR systems sense the spectrum of the licensed user by using a energy detection method. Threshold is determined in accordance with the constant false alarm rate(CFAR) algorithm for energy detection. The signal of licensed user is OFDM signal and the wireless channel between a licensed user and CR systems is modeled as Gaussian channel. From the simulation results, the cooperative spectrum sensing with distance based weight combining(DWC) and equal gain combing(EGC) methods shows higher spectrum sensing performance than single spectrum sensing does. And the detection probability performance with the DWC is higher than that with the EGC.

• Journal of the Korean Solar Energy Society
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• v.29 no.2
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• pp.31-38
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• 2009

This study was conducted to forecast inner water temperature strata change by extracting deep water from a dam. For the methodology, the scope wherein the balance between the volume of low-temperature water intake through the virtual water intake opening as installed within the stored water area and the volume of water intake from the surrounding area is not destroyed was calculated through the CFD simulation technique using the computational fluid dynamics(CFD) interpretation method. This study suggested a supplementary method(diffuser) to avoid destroying the water temperature strata, and the effect was reviewed. In case of intake of the same volume, when the velocity of flow of water intake is reduced by increasing the pipe diameter, the destruction of water temperature strata can be minimized. When the area(height) where the intake of water is possible is low, a diffuser for interrupting the vertical direction inflow should be installed to secure favorable water intake conditions in case of water intake on the upper part. This study showed that there was no problem if the intake-enabled, low-temperature area was secured approximately 10m from the bottom when the scope that does not destroy the water temperature strata in case of water intake was forecast using the regression formula.

• Journal of the Korean Ceramic Society
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• v.43 no.5 s.288
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• pp.270-276
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• 2006

LSGM(($La_xSr_{1-x})(Ga_yMg_{1-y})O_3$) electrolyte is known to show very serious interfacial reaction with other unit cell components, especially with an anode. Such an interfacial reaction induced the phase instability of constituent component and deterioration of the unit cell performance, which become the most challenging issues in LSGM-based SOFCs. In this study, we fabricated LSGM($La_{0.8}Sr_{0.2}Ga_{0.83}Mg_{0.17}O_x$) electrolyte supported-type cell in order to avoid such interfacial problem by lowering the heat-treatment temperature of the electrode fabrication. According to the microstructural and phase analysis, there was no serious interfacial reaction at both electrolyte/anode and electrolyte/cathode interfaces. Moreover, from the electrochemical characterization of the unit cell performance, there was no distinct deterioration of the open cell voltage as well as an internal cell resistance. These results demonstrate the most critical point to be concerned in LSGM-based SOFC is either to find a proper electrode material which will not give any interfacial reaction with LSGM electrolyte or to properly adjust the processing variables for unit cell fabrication, to reduce the interfacial reaction.

• Journal of the Korea Society of Computer and Information
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• v.22 no.7
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• pp.55-62
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• 2017

Recently, there has been an increasing need for the sharing of microdata containing information regarding an individual entity. As microdata usually contains sensitive information on an individual, releasing it directly for public use may violate existing privacy requirements. Thus, to avoid the privacy problems that occur through the release of microdata for public use, extensive studies have been conducted in the area of privacy-preserving data publishing (PPDP). The k-anonymity algorithm, which is the most popular method, guarantees that, for each record, there are at least k-1 other records included in the released data that have the same values for a set of quasi-identifier attributes. Given an original table, the corresponding k-anonymous table is obtained by generalizing each record in the table into an indistinguishable group, called the equivalent class, by replacing the specific values of the quasi-identifier attributes with more general values. However, query processing over the anonymized data is a very challenging task, due to generalized attribute values. In particular, the problem becomes more challenging with an equi-join query (which is the most common type of query in data analysis tasks) over k-anonymous tables, since with the generalized attribute values, it is hard to determine whether two records can be joinable. Thus, to address this challenge, in this paper, we develop a novel scheme that is able to effectively perform an equi-join between k-anonymous tables. The experiment results show that, through the proposed method, significant gains in accuracy over using a naive scheme can be achieved.

• Journal of Korea Port Economic Association
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• v.28 no.1
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• pp.105-122
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• 2012

This paper proposes a fuzzy-based AHP model by which the greenhouse gas reduction for container terminal problem was systematically structured and then evaluated. The model was established by exploiting a fuzzy theory and AHP for capturing the inexactness and vagueness of information. In this study, measurement areas were selected for equipment aspect, operating aspect, and energy aspect. The greenhouse gas reduction is the number one priority in the equipment aspect, operating aspect, energy aspect in order. The analysis result of equipment aspect reveals that the most important element is electrical T/C. The most important element of operating and energy aspect were a container rehandling and a LED lighting. As for the whole priority which conversion weight was applied, the results were shown as follows: an electrical T/C(16.2%) as the first rank: a hybrid Y/T(14.4%) as the second rank: a AMP(10.6%) as the third rank. The result of this study suggests some guidelines for deciding priority of greenhouse gas reduction for container terminal.

• Informatization Policy
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• v.19 no.4
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• pp.27-45
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• 2012

Smart grid, which is a sort of convergence of numerous technologies, can be deployed only with cooperation and fair competition among various stakeholders. If the interest conflicts were not coordinated properly, related business and investment would become delayed and inactive. Therefore, this study analyzes the causes of interest conflicts and related issues in smart grid sector and suggests policy directions by issue. As the result of AHP analysis, the majority of respondents surveyed said that ambiguity of the role and authority is the key problem causing conflicts of interest in smart grid deployment process. Differences in values, communications problems, etc. are pointed as additional main reasons of the interest conflicts. To resolve interest conflicts in smart grids, the Korean government should enhance its leadership in the coordination of stakeholders' interests. Government should make efforts to coordinate the various interests in terms of the development of the smart grid market and win stakeholders' sympathy of their desirable roles in the smart grid market.

• Hwankyungkyoyuk
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• v.15 no.2
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• pp.86-99
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• 2002

The purpose of this study is to make clear the management of Environmental Education in Elementary school in Korea. To accomplish this purpose, The research for the actual condition of management of Environmental Education according to school, grade, and class was progressed. The researcher was analyzed Hindrance Factors of Sound Environmental Education in School and presented some suggestion on the basis of above-mentioned findings. On one side, the method of research is a case study on qualitative based way. A case study was conducted with it's focus on public elementary school in Seoul. As for major research methods, observation by participating in school field and in-depth interview were respectively employed; subsidiary methods included literature study. The findings of this study are as belows: First, Environmental Education was not managed practically with specific way in school. Second, Environmental Education by direct and actual outdoor experience was unusual. Third, most of class school work about Environmental Education was focused on not only the type of prescription after the environmental problem but also, the treatment of articles in newspaper and TV. Forth, educational compulsion such as “you have to do that.” was mainly used as Environmental guidance for sound attitude in school without clear reasons. In the last analysis, hindrance factors of sound management for environmental education in elementary schools were ‘passive adjustment’, ‘discriminative reception’, ‘absence of information resource’. these factors came from atmosphere of negligence environmental education in schools. Therefore, all of teachers have to affirmative belief and attitude as personal dimension and all of elementary schools improve environmental education system.

• Journal of Convergence Society for SMB
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• v.4 no.3
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• pp.1-6
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• 2014

DDoS (Distributed Denial Service, Distributed Service) attacks are being generated for a constant threat on the Internet, countermeasures for this have been proposed. However, the problem has become an increasingly effective instruction in any Measures are a variety of attacks and sophisticated attacks. Attackers can change a steady attack tools to respond to these, the experts as a countermeasure to this constantly research for a fresh attack. This paper is to introduce countermeasures to DDoS recent representative examples of 7.7DDoS and look for 3.3DDoS existing types of DDoS attacks increased PPS attacks, high traffic sent, web service delay and router and firewall settings, applications and to describe the DDoS countermeasures research by certification, is so that you can plan effectively for the future DDoS attacks proposed method.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.2
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• pp.92-98
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• 2017

Data clustering determines a group of patterns using similarity measure in a dataset and is one of the most important and difficult technique in data mining. Clustering can be formally considered as a particular kind of NP-hard grouping problem. K-means algorithm which is popular and efficient, is sensitive for initialization and has the possibility to be stuck in local optimum because of hill climbing clustering method. This method is also not computationally feasible in practice, especially for large datasets and large number of clusters. Therefore, we need a robust and efficient clustering algorithm to find the global optimum (not local optimum) especially when much data is collected from many IoT (Internet of Things) devices in these days. The objective of this paper is to propose new Hybrid Simulated Annealing (HSA) which is combined simulated annealing with K-means for non-hierarchical clustering of big data. Simulated annealing (SA) is useful for diversified search in large search space and K-means is useful for converged search in predetermined search space. Our proposed method can balance the intensification and diversification to find the global optimal solution in big data clustering. The performance of HSA is validated using Iris, Wine, Glass, and Vowel UCI machine learning repository datasets comparing to previous studies by experiment and analysis. Our proposed KSAK (K-means+SA+K-means) and SAK (SA+K-means) are better than KSA(K-means+SA), SA, and K-means in our simulations. Our method has significantly improved accuracy and efficiency to find the global optimal data clustering solution for complex, real time, and costly data mining process.