• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.631-634
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• 2009

Recent advances in wireless communication, electronics, MEMS device, sensor and battery technology have made it possible to manufacture low-cost, low-power, multi-function tiny sensor nodes. A large number of tiny sensor nodes form sensor network through wireless communication. Sensor networks represent a significant improvement over traditional sensors, research on Zigbee wireless image transmission has been a topic in industrial and scientific fields. In this paper, we design a Zigbee wireless image sensor node and multimedia monitoring server system. It consists of embedded processor, memory, CMOS image sensor, image acquisition and processing unit, Zigbee RF module, power supply unit and remote monitoring server system. In the future, we will further improve our Zigbee wireless image sensor node and monitoring server system. Besides, energy-efficient Zigbee wireless image transmission protocol and interworking with mobile network will be our work focus.

• Proceedings of the Korea Information Processing Society Conference
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• 2010.04a
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• pp.218-221
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• 2010

현재 중복 제거 기술은 클라이언트 기반 중복 제거 모델, 인라인(in-line) 중복 제거 모델 그리고 포스트 프로세스(post-process) 중복 제거 모델로 구분할 수 있다. 본 연구에서는 클라이언트와 서버의 부하를 모니터링하여 시스템 부하에 따라 중복 제거의 핵심 작업을 동적으로 변경한다. 즉, 클라이언트가 유휴하고 서버의 자원 사용량이 높은 경우에는 클라이언트 기반 중복 제거 모델로 동작시키고, 클라이언트의 자원 사용량이 높고 서버가 유휴한(idle) 경우에는 인라인 중복 제거 모델로 동작시킨다. 그리고 전체 시스템이 과부하인 경우는 포스트 프로세스 모델로 동작하게 된다. 제안하는 방식에 대한 실험 결과 전체 시스템의 처리율이 높아지는 것을 확인하였다.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.5
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• pp.817-824
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• 2021

The SDN(Software Defined Networking) technology, which appeared to overcome the limitations of the existing network system, resolves the rigidity of the existing system through the separation of HW and SW in network equipment. These characteristics of SDN provide wide scalability beyond hardware-oriented network equipment, and provide flexible load balancing policies in data centers of various sizes. In the meantime, many studies have been conducted to apply the advantages of SDN to data centers and have shown their effectiveness. The method mainly used in previous studies was to periodically check the server load and perform load balancing based on this. In this method, the more the number of servers and the shorter the server load check cycle, the more traffic increases. In this paper, we propose a new load balancing technique that can eliminate unnecessary traffic and manage server resources more efficiently by reporting to the controller when a specific level of load occurs in the server to solve this limitation.

• Proceedings of the Korea Information Processing Society Conference
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• 2003.11a
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• pp.209-212
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• 2003

인터넷 서비스 서버들의 가용성과 확장성, 부하분산의 특성들을 가지는 클러스터 시스템에서 성능관리와 이상상황관리를 위해서 본 논문에서는 성능 모니터링을 통하여 클러스터 시스템으로부터 필요한 자료를 수집할 수 있는 구조와 성능 분석을 위한 수집해야하는 정보들의 분석과 수집된 데이터를 분석하기 위한 다양한 분석 방법론을 제시한다. 이러한 성능 분석을 통해 자원사용, 확장성 가용성, 부하분산, 서비스의질, 이상상황 추적 등을 고려하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2000.04a
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• pp.307-310
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• 2000

인터넷 이용자들의 증가로 인해 개방된 네트워크에서의 실시간 분산환경이 고려되고 있으며, 이들 분산된 정보 및 컴퓨터 자원들에 대한 접근 요구가 증대됨에 따라 네트워크 상호연결 요구또한 커지고 있다. 이러한 정보제공에 대한 이용자들의 요구를 충족시키기위해 다중 서버를 두고 이들 서버간에 네트워크의 성능을 효율적으로 감시하고 제어하기 위한 모니터링 서버를 제공함으로써 분산 시스템의 성능 향상은 물론 이용자 입장에서의 정보에 대한 응답시간과 반환시간을 최소화하고, 시스템의 전반적인 측면에서의 작업 처리율과 자원의 활용도를 최대화 할수 있으며, 동적인 상황에 따라 스스로 판단하고 적절하게 대응할 수 잇는 지능형 이동 에이전트 템플릿을 설계구현하였다.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.12
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• pp.568-575
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• 2008

Server consolidation by sever virtualization can make one physical machine(PM) to run several virtual machines simultaneously. Although It is attractive in cost, it has complex workload behaviors. For that reason, efficient resource management method is required. Dynamic relocation of virtual machine(VM)[3,4] by live migration[1,2] is one of resource management methods. We proposed SCOA(Server Consolidation Optimizing Algorithm) : a fine-grained load balancing mechanism worked on this dynamic relocation mechanism. We could obtain accurate resource distribution information through pointed physical machines on multi dimensional resource usage coordination, so we could maintain more balanced resource state. In this paper, we show the effectiveness of our algorithm by comparison of experimental results between SCOA and sandpiper[3] by software simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.7-13
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• 2019

Unlike a typical video wall system, video wall systems used for integrated monitoring in smart city environments should be able to display various videos, images, and texts simultaneously. In this paper, we propose an Internet Protocol (IP)-based video wall system that has no limit on the number of videos that can be monitored simultaneously, and that can arrange the monitor screen layout without restrictions. The proposed system is composed of multiple display servers, a wall controller, and video source providers, and they communicate with each other through an IP network. Since the display server receives and decodes the video stream directly from the video source devices, and displays it on the attached monitor screens, more videos can be simultaneously displayed on the entire video wall. When one video is displayed over several screens attached to multiple display servers, only one display server receives the video stream and transmits it to the other display servers by using IP multicast communications, thereby reducing the network load and synchronizing the video frames. Experiments show that as the number of videos increases, a system consisting of more display servers shows better decoding and rendering performance, and there is no performance degradation, even if the display server continues to be expanded.

• The Journal of the Korea Contents Association
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• v.5 no.2
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• pp.79-85
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• 2005

In order to handle client's requests while multiple servers seamlessly work in the web server cluster environment, it is vital to implement a router that execute a routing using TCP information and requested target content. The implemented package software measured packet volume that was generated from data generator, virtual server, and server 1, 2, 3, and could find out traffic distribution toward Server 1, 2, 3. As the result of the study shows, Round Robin Algorithm ensured definite traffic distribution, unless incoming data loads differ much. Although error levels were high in some partial cases, they were eventually alleviated by repeated tests for a longer time.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.197-202
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• 2010

In this paper, multi-channel vital signal monitoring system was implemented for home healthcare. The system able to measure vital signal for example ECG, PPG and temperature simultaneously at patients’ home. The vital signal is an essential parameter for healthcare application and can be easily extracted from patients. The implemented system consist of sensor parts for signal extraction, signal amplifier and filter for analog circuit, analog signal to digital conversion for controlling devices and lastly the monitoring program. The system able to transmit vital signals using Bluetooth wireless communications to personal computer or home server. And the tele-monitoring system able to display real-time signals using web monitoring program. In medical application, the vital signal parameter able to stored and saved in the web server for further medical analysis. This system opens up the possibilities of ubiquitous healthcare where further implementation can be easily done.

• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.107-115
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• 2011

The line-telemetry data processing system is necessary for monitoring the status of each onboard systems of KSLV-I upper stage during the ground tests and launch preparation. The mission of line-telemetry system is to provide reference telemetry data and to monitor the status of upper stage. The line-telemetry data processing system consists of a PCM acquisition/processing server, a system management server, and 9 monitoring consoles. In this paper, we will describe the overview of onboard remote measurement system, the design of the line-telemetry data processing system, anomaly setup information for indicating alarm signal in case of abnormal occurrence, and the result of the ground test and flight test.