• Journal of The Korean Association For Science Education
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• v.39 no.1
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• pp.129-141
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• 2019

As the number of minority students such as multicultural, North Korean defectors, and low-income groups increases, more research is needed in science education to help their learning. Due to the various growth backgrounds and learning environments of the underprivileged students, there is a big difference in the individual characteristics of the group rather than the whole group characteristics. In this study, we conducted about 50 hours of science lessons for seven students in the underprivileged class, categorized them by observing and interviewing the characteristics of their science learning. Seven underprivileged students showed five different learning patterns, these are 'I love science', 'I think I know science', 'I want to know science', 'I need to know science', and 'I don't know what I want'. Although the scientific activities they experienced were not all of an excellent educational quality, their interest in science learning has increased with their experience in science activities. It shows the need to provide more abundant science experience and educational opportunities for these minority students who can only experience science learning under the public educational system.

• Journal of the Korea Society of Computer and Information
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• v.18 no.8
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• pp.95-104
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• 2013

DDoS attacks have became as a social threat since 2009 7.7 DDoS turmoil. Even though defence techniques have been developing to provide against those threats, they become much more sophisticate. In recent years, the attack form of DDoS is changing from high amount of traffic attack of network layers to highly sophisticate small amount of application layers. To make matters worse, attack agent for the attack has became very intelligent so that it is difficult to be blocked since it can't be distinguished from normal PCs. In the user authentication system(such as CAPTCHA) User intervention is required to distinguish normal PCs and intelligent attack agents and in particular, in a NAT environment, IP-based blocking method can be cut off the normal users traffic at the same time. This research examined defense techniques which are able to distinguish between agent and normal PC and effectively block ways the HTTP DDoS offense applying one-time session key based authentication method using Cookie which is used in HTTP protocol to protect web sever from sophisticate application layer of DDoS.

• Journal of Korean Library and Information Science Society
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• v.34 no.4
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• pp.203-226
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• 2003

The purpose of this study aims to provide possible suggestions for the improvement of the korean Decimal Classification System in 21th century through the analysis of language field as the subject of study. As a result of this study, some problems(for example, irrational classification number system, very simplicity of $\ulcorner$Subdivisions of Individual languages md languages families$\lrcorner$, improper languages development insufficiency of note etc.) were found out. This study can be useful for the future revision of KDC4 because a revolutionary improvement were provided.

• Journal of Korean Library and Information Science Society
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• v.35 no.2
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• pp.135-154
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• 2004

This study was investigated to the geographical categories and arrangement of library classifications and public organizations in ender to understand the geographical category comprehension and canon from the north-west to south-east in Korean library classification and then to develop a Korean geographical classification system Research method was the examination of different type of library classification (DDC, NDC, LCC) and geographical categorizations of the public organizations. The results show that there was not a principle of categorization and arrangement for geographical information. This study proposes to the three hierarchical structures and radial category arrangement from center-area to side area for developing Km geographical classification.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.504-504
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• 2015

수공구조물을 설계하기 위해서는 설계수문량을 빈도해석을 통해 산정할 수 있다. 빈도해석 중 지점빈도해석을 보완한 지역빈도해석을 적용하기 위해서는 군집분석을 통한 지역구분이 무엇보다 중요하다. 또한 스케일 성질(scaling property)은 강우의 시 공간적 특성을 지속기간별 관측된 강우자료를 이용하여 재현기간에 대한 지속기간의 함수로 강우의 IDF곡선을 제시할 수 있는 방법이다. 따라서 스케일 성질을 통해 군집된 지역에서의 강우자료에 적용하여 스케일 인자(scaling exponent)를 추정한 후 수문학적 동질성을 통계적 특성으로 설명하고자 한다. 본 연구를 수행하기에 앞서 군집 분석은 4개의 군집방법(평균연결법, Ward방법, Two-Step방법, K-means방법)을 적용하였고, 한강유역에 위치한 104개의 강우지점은 4개의 지역으로 구분하는 것이 적절하다고 판단되어 비계층적 방법인 k-means방법을 이용하여 지역을 구분하였다. 본 연구에서는 군집된 결과를 바탕으로 4개의 지역으로 구분된 지역에 포함된 강우지점을 대상으로 스케일 인자를 추정하고 수문학적 동질성을 통계적 방법으로 제시하고자 한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.8
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• pp.889-897
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• 2014

With the development of wireless communication and sensor technology, sensor network applications in various fields have been applied. To minimize the power consumption of sensors in sensor network is one of the important factors in oder to extend the system life. The power consumption of each sensor within sensor network can be different depending on the communication method between head(sink) node and its node. In this paper, we propose a new hierarchical communication method to minimize the power consumption of each sensor. The proposed method divides the area of sensor network into four areas using divide-and-conquer method and selects the nearest node to head node in each area as a child node of the node. Next the hierarchical tree in the same way is constructed recursively until each area is no longer divided. Each sensor can communicate to head node using this hierarchical tree. The proposed results were compared with the previous methods through simulation, and showed excellent results in the energy efficiency of sensor network.

• Journal of the Korean association of regional geographers
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• v.13 no.5
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• pp.477-494
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• 2007

This paper offers a brief overview of the historical implications of residential segregation in Busan, Korea. It first reviews the history of residence from the early 1900s to the present and the transition of residential boundary of the City of Busan. It then considers the characteristics of residential segregation and the important factors in it. The social class of pre-industrial society led the inequality of residential areas around the Eubchee. The existed Korean residential areas were separated by newly built-up residential areas in the Japanese colonial era. After the liberation from Japanese Rule and Korean War, rapid population growth made considerable slums across the City of Busan. These slums were an important factor to segregate residential areas from prosperous areas ever afterward. The socio-economic status has related to residential segregation through the formation of differential housing classes since 1990s. The historial analysis of these periods will offer an insight into how the dominant factors lead residential segregation in a specific period by promoting a more socio-economically integrated society.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.4
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• pp.313-318
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• 2002

The Integration of agent technology and security technology is needed to many application areas like electronic commerce. This paper suggests a model of extended multi-agent engine which supports privacy, integrity, authentication and non-repudiation on agent communication. Each agent which is developed with the agent engine is composed of agent engine layer and agent application layer. We describe and use the concepts self-to-self messages, secure communication channel, and distinction of KQML messages in agent application layer and messages in agent engine layer. The suggested agent engine provides an agent communication language which is extended to enable secure communication between agents without any modifications or restrictions to content layer and message layer of KQML. Also, in the model of our multi-agent engine, secure communication is expressed and processed transparently on the agent communication language.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.27 no.1
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• pp.313-336
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• 2016

The study reviews theoretical and empirical research literature in information needs, seeking and uses in order to search for the most pertinent metatheories for studying information practices of the disadvantaged. The study examines the salient features and main theories/models of each cognitive, affective and social approach in the user-centered paradigm through analyzing prior information practices studies. While analyzing the main features of each cognitive, affective and social approach, the study points out the limitation of research using the cognitive and affective approaches to fail to theorize the relationship between individuals and complex and dynamic socio-cultural contexts in information practices. As an alternative, the study suggests using the social approach as a pertinent metatheory for understanding information practices of the disadvantaged who are entangled with myriad social contexts and issues. In order to verify the pertinence, the study examines the advantages of the social approach through analyzing both the main models related to everyday information practices under social constructionism and the main findings from information practices of the disadvantaged.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.1
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• pp.77-85
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• 2006

In this paper, we propose a hierarchical classifier of object images using neural networks for content-based image classification. The images for classification are object images that can be divided into foreground and background. In the preprocessing step, we extract the object region and shape-based texture features extracted from wavelet transformed images. We group the image classes into clusters which have similar texture features using Principal Component Analysis(PCA) and K-means. The hierarchical classifier has five layes which combine the clusters. The hierarchical classifier consists of 59 neural network classifiers learned with the back propagation algorithm. Among the various texture features, the diagonal moment was the most effective. A test with 1000 training data and 1000 test data composed of 10 images from each of 100 classes shows classification rates of 81.5% and 75.1% correct, respectively.