• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.484-488
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• 2008

AHU(Autonomic Healing Utility)는 결함발생요인을 관리하고 결함이 발생할 가능성이 있는 응용프로그램을 검출하기 위하여 결함예방서비스와 더불어 프로액티브한 결함복구서비스를 지원한다. Server-Client 구조를 갖는 AHU는 하나의 AHU 서버에 너무 많은 AHU 클라이언트들이 자가치유 서비스를 요청하는 경우 병목현상이 발생하여 AHU 서버의 처리용량을 넘게 되고 AHU가 제공하는 자가치유시간을 증가시켜 자가치유서비스의 질을 저하시키거나 AHU의 SPOF(Single Point of Failure)로 작용하여 AHU의 전반적인 결함을 발생시키는 원인이 된다. 따라서 본 논문에서는 AHU 시스템의 부하를 분산시켜서 AHU 서버에 생기는 병목현상을 해소하기 위한 방법을 제안하고 이를 구현하여 기존의 AHU와 AHU 서버들 사이의 부하분산 방법을 적용한 AHU를 비교하는 성능평가를 수행하였다.

• International Journal of Contents
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• v.2 no.2
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• pp.29-31
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• 2006

Mobile Ad hoc network is a self configuring network of mobile nodes. It allows mobile nodes to configure network spontaneously and share their services. In these networks, service discovery is very important because all nodes do not have same resources in term of memory and computing power. Nodes need to use different services offered by different servers. Some service discovery protocols have been proposed in last couple of years but they include significant traffic overhead and for small scale MANETS. In this paper, we present extensible lookup service scheme based on distributed mechanism. In our scheme neighboring nodes of service provider monitor service provider and send notification to lookup server when the service provider terminates its services unexpectedly. Lookup server can find other service provider or other alternative services in advance because of advance notification method and can provide consistent lookup services. In our scheme neighboring nodes also monitor lookup server and send notification to network when lookup server terminates unexpectedly. Simulation results show that our scheme can reduce up to 70% and 30% lookup failure as compare to centralize and simple distributed mechanism respectively.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.788-792
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• 1993

The objective of this study is to develope a satellite dynamic simulator, which can test and analyze the performance of spacecraft attitude control, antenna pointing instruments, communication equipments and spacecraft components under the space environment. The satellite simulator can be used to predict the events such as malfunction and failure of satellites in space during operation and can be used to protect against emergencies. At first, the performance test system of attitude control is investigated which can simulate motion and verify stability of spacecraft. Our system consists of an attitude control main processor and a sub-processor including some real hardwares such as attitude sensors and actuators. In this paper, we describe the procedure of designing and manufacturing the dynamic simulator hardware, which consists of the central processor board, the sub-processor board and the sun sensor, and also communication between the components.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.43-48
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• 2011

In this paper, We have investigated the weak waterproofing defection characteristic of polymer humidity sensor and identified the cause of failure. In high temperature and high humidity conditions(($60^{\circ}C/95%$), the defecting process is simulated about defective and improved samples which are modified for the crosslinking polymer structure's aspect. It is aimed at the defecting reason and suggestion of defection process mechanism.

• International journal of advanced smart convergence
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• v.1 no.2
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• pp.26-29
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• 2012

Recently, to efficiently support the real-time requirements of RTLS( Real Time Location System) services, interest in the main memory DBMS is rising. In the main memory DBMS, because all data can be lost when the system failure happens, the recovery method is very important for the stability of the database. Especially, disk I/O in executing the log and the checkpoint becomes the bottleneck of letting down the total system performance. Therefore, it is urgently necessary to research about the recovery method to reduce disk I/O in the main memory DBMS. Therefore, In this paper, we analyzed existing log techniques and check point techniques and existing main memory DBMSs' recovery techniques for recovery techniques research for main memory DBMS.

• International journal of advanced smart convergence
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• v.7 no.2
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• pp.67-72
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• 2018

On the internal based search, the big data inference, which is failed in the president's election in the United States of America in 2016, is failed, because the prediction method is used on the base of the searching numerical value of a candidate for the presidency. Also the Flu Trend service is opened by the Google in 2008. But the Google was embarrassed for the fame's failure for the killing flu prediction system in 2011 and the prediction of presidential election in 2016. In this paper, using the virtual vote algorithm for virtual election and data mining method, the election prediction algorithm is proposed and unpacked. And also the WEKA DB is unpacked. Especially in this paper, using the K means algorithm and XEDOS tools, the prediction of election results is unpacked efficiently. Also using the analysis of the WEKA DB, the smart election prediction system is proposed in this paper.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1549-1552
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• 2005

네트워크에 연결된 장치나 자원은 심각한 네트워크 단절로 인해 사용이 불가능할 수도 있다. 견고한 네트워크 연결성을 제공하기 위해 본 논문에서는 협력작업(teamwork)을 이용한 UPnP 환경에서의 자동화된 복구 방법을 제안한다. 제안한 복구 방법에서는 복구 가능한 제어 포인트(control point)들과 이와 연관된 복구 장치들이 팀을 이루어 제어 포인트에 장애(failure)가 발생하여도 다른팀 구성원이 장치들을 자동으로 연결하여 공통의 목표를 달성한다. 제안한 복구 방법이 효과적임을 실험을 통해 검증하였는데, 이 실험에서 복구 가능한 제어 포인트는 팀 내의 다른 제어 포인트에 장애가 발생하였을 경우에도 장치로부터의 이벤트를 성공적으로 처리하였다.

• Journal of Information Technology Applications and Management
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• v.20 no.3
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• pp.105-127
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• 2013

Information and Communication Technology (ICT) has become a vital instrument for delivering a number of services such as education, healthcare and public services. Community wireless networks are community-centric telecommunication infrastructure developed to provide affordable communication for those who live in remote areas. This chapter discusses the role of Nepal Wireless in achieving socio economic development of rural communities by facilitating affordable Internet access. We analyze the challenges Nepal Wireless faced and articulate on the approaches it took to address those challenges such as lack of technical skills, appropriate technology and funding, difficult geographical terrains, unstable political situation, and expensive devices. In addition, we address the success and failure factors of this community-based ICT4D approach in order to guide similar endeavors. We conclude the chapter by some suggestions for policy makers, community developers, and academicians.

• ETRI Journal
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• v.38 no.5
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• pp.896-902
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• 2016

Luby transform (LT) codes were the first practical rateless erasure codes proposed in the literature. The performances of these codes, which are iteratively decoded using belief propagation algorithms, depend on the degree distribution used to generate the coded symbols. The existence of degree-one coded symbols is essential for the starting and continuation of the decoding process. The absence of a degree-one coded symbol at any instant of an iterative decoding operation results in decoding failure. To alleviate this problem, we proposed a method used in the absence of a degree-one code symbol to overcome a stuck decoding operation and its continuation. The simulation results show that the proposed approach provides a better performance than a conventional LT code and memory-based robust soliton distributed LT code, as well as that of a Gaussian elimination assisted LT code, particularly for short data lengths.

• Journal of Applied Reliability
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• v.6 no.4
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• pp.297-306
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• 2006

In this paper, We presented the algorithm for estimating a reliability between nodes in wireless distributed sensor networks (DSN). To estimate the reliability between nodes, we first modeled DSN as probability graph. Links of the graph are always reliable and the probability of node failure is independent. After all possible simple path which can be established between two nodes are examined, we perform sharp operation to remove repetition event between two nodes. Using probability for each variable of the minimized Boolean equation, we present the reliability formula.