• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.597-604
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• 2007

Stream data is a continuous flow of information that mostly arrives as the form of an infinite rapid stream. Recently researchers show a great deal of interests in analyzing such data to obtain value added information. Here, we propose an efficient cube computation algorithm for multidimensional analysis of stream data. The fact that stream data arrives in an unsorted fashion and aggregation results can only be obtained after the last data item has been read. cube computation requires a tremendous amount of memory. In order to resolve such difficulties, we compute user selected aggregation fables only, and use a combination of an way and AVL trees as a temporary storage for aggregation tables. The proposed cube computation algorithm works even when main memory is not large enough to store all the aggregation tables during the computation. We showed that the proposed algorithm is practically fast enough by theoretical analysis and performance evaluation.

• Journal of the Korea Society of Computer and Information
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• v.10 no.6 s.38
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• pp.153-166
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• 2005

Existing single cache structure has shown difference of hit-ratio according to individually replacement strategy However. It needs new improved cache structure for reducing network traffic and providing advanced hit-ratio. Therefore, this Paper design push agent model using dual cache for increasing hit-ratio by reducing server overload and network traffic by repetition request of persistent and identical information. In this model proposes dual cache structure to do achievement replace gradual cache using by two caches storage space for reducing server overload and network traffic. Also, we show new cache replace techniques and algorithms which executes data update and delete based on replace strategy of Log(Size) +LRU, LFU and PLC for effectiveness of data search in cache. And through an experiment, it evaluates Performance of dual cache push agent model.

• Journal of Intelligence and Information Systems
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• v.16 no.3
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• pp.15-35
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• 2010

Web service Technology has been developing rapidly as it provides a flexible application-to-application interaction mechanism. Several ongoing research efforts focus on various aspects of Web service technology, including the modeling, specification, discovery, composition and verification of Web services. The approaches advocated are often conflicting-based as they are differing expectations on the current status of Web services as well as differing models of their future evolution. One way of deciding the relative relevance of the various research directions is to look at their applicability to the currently available Web services. To this end, we conducted a survey on currently publicly available Web service repositories. Our aim is to get an idea of the number, complexity and composability of these Web services and see if this analysis provides useful information about the near-term fruitful research directions.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.16 no.5
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• pp.47-57
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• 2006

Mobile Ad-hoc networks have various implementation constraints such as infrastructure-free, no trusted authority, node mobility, and the limited power and small memory of mobile device. And just like wired networks, various security issues such as authentication, confidentiality, integrity, non-repudiation, access control, availability and so on have been arisen in mobile Ad-hoc networks. But we focus on authentication of these security issues because it is quitely affected by the characteristics of networks. In this paper, we propose the authentication protocol that can limit the size of certificate repository as $log_2N$ and assures to make a trusted certificate path from one node to another, adopting the concept of Hamming distance. Particularly, our protocol can construct a trusted certificate path in spite of decreasing or increasing the number of nodes in mobile Ad-hoc network.

• Smart Media Journal
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• v.11 no.5
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• pp.56-62
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• 2022

Water reservoir is defined as a storage space to hold and supply filtered water and it's significantly important to manage water level in the water reservoir so as to stabilize water supply by controlling water supply depending on demand. Liquid level sensors have been installed in the water reservoir and the pumps in the booster station facilitated management for optimum water level in the water reservoir. But the incident responses including sensor malfunction and communication breakdown actually count on manager's inspection, which involves risk of accidents. To stabilize draining facility management, this study has come up with AI model that predicts changes in the water level in the water reservoir. Going through simulation in the case of missing data in the water level to verify stability in relation to the field application of the prediction model for water level changes in the reservoir, the comparison of actual change value and predicted value allows to test utility of the model.

• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.123-131
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• 2009

In this paper, we design ZigBee RF based framework for mobile web service on collected data by sensor node and transmitting data to data base by sensor network and remote sensing server through wireless connection. The proposed system is an integrated platform of sensor network for the sensor management and providing SOA based sensor web access. This paper combines SOA technology with sensor network. composes sensor node as web view, and provides high capability. extensiveness, reliability, and usability to the user who accesses to sensor web. The mobile message conversion module, SOAP message processing module. WSDL message generator, and mobile web service module is embodied for improving the capacity of the framework. The capacity evaluation of local wireless communication system which is proposed in this paper is analyzed through NS-2 simulation.

• Journal of the Korean Home Economics Association
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• v.29 no.2
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• pp.77-86
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• 1991

본 연구의 목적은 1) 집단 급식소의 재고 관리 시스템에 관한 자기학습식 Module (Self-instructional Module)을 개발하고, 2) 비동등 통계 실험연구 디자인 (Nonequivalent Control group research design)을 사용하요 자기학습식 재고 관리 시스템 Module의 교육적 효과를 평가하여, 3) 교육기관 및 집단 급식소에서의 교육용 교재로서의 타당성 여부를 검증하고자 함이다. 집단급식소의 재고 관리 시스템에 관한 자기학습식 Module을 개발하기 위해서 현재 미국 전역의 가정대학 내의 식품영양 및 급식경양학과에서 재고 관리에 관련된 교과목을 위하여 채택되어 사용되어지고 있는 주요 교과서들의 내용 분석과 급식경영학 전공 교수 3인의 판단에 기초를 두어 재고관리에 포함되어야 할 내용이 분석되었다. 포함되어져 있는 내용의 목차는 반입(receiving), 저장(storing), 출고(issuing), 재고통제(inventory control), 재고의 자산적 가치(inventory valuation) 및 재고관리 시스템의 자동화(inventory control computer system)등이다. 실험 대상은 Iowa 주립대학에서 급식정보관리 (Foodservice Management Information System) 과목을 수강하였던 88명의 학생이며, 강의를 통해 수업을 받은 통제집단 46명과, 자기 학습식 Module을 사용했던 실험집단 42명으로 구성되었다. 모든 실험 대상에게는 사전검사(Pretest)와 사후검사(posttest)를 실시하였으며 자료의 처리는 SPSS PC Package를 통계법으로 분석하였다. 연구결과는 강의 중심의 통제집단과 자기학습식 Module을 사용했던 실험집단 간의 통제 후 평균 값(posttest adjusted mean score)사이에는 유의적인 차이를 보였으며 (p<0.05), 자기 학습식 Module 그룹에 속해 있던 학생들이 더 높은 통제 후 평균값(adjusted mean score)을 보여 주었다. 그러므로, 이 실험을 통하여, 개발된 집단 급식소 재고관리 시스템에 대한 자기학습식 Module은 학생들에게 재고관리 시스템에 관한 개념과 내용의 습득력을 향상시키는데 있어서 적어도 강의식 교수법과 동일하거나 더나은 교육적 효과를 가져왔다고 판단되었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.142-148
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• 2017

Along with economic growth in the 1970s, the nation's economy, railroads, and airports have soared, but the facilities have been aging for 30 years. The aging SOC lowers the national competitiveness and threatens the safety of the people. SOC is a key asset of the national life and economic activity, and is a key factor for evaluating the national competitiveness. Therefore, it is necessary to systematically manage and operate the SOC related to people's lives. In the USA, the SOC report card is issued regularly. Those reports are used as a basis for securing budgets. In Korea, facilities management institutions are different. Therefore, there is no integrated SOC monitoring system. Hence, this study developed a 'SOC information system' that can collect reports scattered throughout the country and support report cards. The demonstration system was implemented through the web and the feasibility of implementing the evaluation support system was confirmed. The collection distributed SOC data should be supported by national policy. Although it takes a long time, it is necessary to improve national competitiveness and public safety.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.61-68
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• 2015

Recently, with increasing use of smartphones, the security threats also have increased rapidly. Especially, the compromised smartphone is very dangerous because it could be exploited in a DDOS attacks such as cyberterrorism as well as in the leakage of personal information. However, most bot detection mechanisms are still unsuitable for smartphone with its lower computing capability and limited battery capacity because they incur additional computational overheads or require pre-defined signatures. In this paper, we present an efficient bot detection mechanism in smartphones. Our mechanism detects effectively bots in outgoing traffic by using a correlation between user events and network traffic. We have implemented its prototype in Android smartphone and measured its performance. The evaluation results show that our mechanism provides low overhead to detect bots in smartphones.

• Journal of Internet Computing and Services
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• v.3 no.2
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• pp.79-85
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• 2002

In open communication architecture, application systems consist of objects distributed in lots of computing nodes. To reduce complexity of development. and management of distributed software, to manage efficiently distributed objects and to provide realtime service, the mechanisms for object group management and communication are needed in distributed environment. In this paper we compose object groups and provide reliable group communication mechanism based on CORBA which can adopt a new service without lots of changes on existing system. Group consist of some subgroups that subgroup manager manages for improving the efficiency of group management and message ordering is kept by using sequencer, Communication method among groups uses multicast based on paint to point communication as well as IP multicast and we provide high performance by using selective retransmission of message through message history, We analyze the performance of the proposed mechanism through simulation in distributed environment.