• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.10
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• pp.2462-2472
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• 2014

Recently, the computing paradigm has been changing and VoIP technology is being revisited to support various services. In this paper, we have designed and implemented the system of software PBX open source Asterisk, hardware platform, and mobile devices to support secured voice service based on VoIP. Specially, we designed the various platform from single board to servers based on XenServer in hardware platform. And we verified the delay test of network traffics and the secured voice communication test based on this platform.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.7
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• pp.613-621
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• 2016

This research connected network equipment, including CCTV, PAGA, IP-PBX, and Legacy, in order to enable the operation and configuration of internal IP-based network equipment in maritime plants and vessels, both in the field and from remote places, and to allow for the support of remotely controlling such equipment. It also realized an operating program for the integrated network equipment management system to enable the monitoring and control of equipment status, operation condition, and notifications from distant places. By applying the operating program to satellite stations and vessels sailing on the sea, a performance test was conducted to evaluate data loss and transmission/reception delay in the communication section between the land and vessels. As a result, this research verified the normal operation of CCTV control and of real-time monitoring and control of the network equipment, including PAGA, IP-PBX, and Legacy under the FBB and MVSAT environments. It was observed that the transmission of CCTV video images with a large volume of data as well as the transmission and reception of voice data were found to be slightly delayed, indicating the need to develop technology to compress and convert data for real-time transmission and reception.

• Journal of the Korea Society for Simulation
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• v.21 no.4
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• pp.91-102
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• 2012

Network port scan attack is the method for finding ports opening in a local network. Most existing IDSs(intrusion detection system) record the number of packets sent to a system per unit time. If port scan count from a source IP address is higher than certain threshold, it is regarded as a port scan attack. The degree of risk about source IP address performing network port scan attack depends on attack count recorded by IDS. However, the measurement of risk based on the attack count may reduce port scan detection rates due to the increased false negative for slow port scan. This paper proposes a method of summarizing 4 types of information to differentiate network port scan attack more precisely and comprehensively. To integrate the riskiness, we present a risk index that quantifies the risk of port scan attack by using PCA. The proposed detection method using risk index shows superior performance than Snort for the detection of network port scan.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10B
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• pp.630-638
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• 2005

As real-time media applications based on IP multicast networks spread widely, the end-to-end QoS (quality of service) provisioning for these applications have become very important. To guarantee the end-to-end QoS of multi-party media applications, it is essential to monitor the time-varying status of both network metrics (i.e., delay, jitter and loss) and system metrics (i.e., CPU and memory utilization). In this paper, targeting the multicast-enabled AG (Access Grid) group collaboration tool based on multi-Party real-time media services, a hybrid monitoring scheme that can monitor the status of both multicast network and node system is investigated. It combines active monitoring and passive monitoring approaches to measure multicast network. The active monitoring measures network-layer metrics (i.e., network condition) with probe packets while the passive monitoring checks application-layer metrics (i.e., user traffic condition by analyzing RTCP packets). In addition, it measures node system metrics from system API. By comparing these hybrid results, we attempt to pinpoint the causes of performance degradation and explore corresponding reactions to improve the end-to-end performance. The experimental results show that the proposed hybrid monitoring can provide useful information to coordinate the performance improvement of multi-party real-time media applications.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.3
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• pp.107-117
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• 2009

Network administrator recognizes the abnormal phenomenon in the managed network by using the alert messages generated in the security devices including the intrusion detection system, intrusion prevention system, firewall, and etc. And then the series of task, which searches for the traffic related to the alert message and analyzes the traffic data, are required to determine where the abnormal phenomenon is the real network security threat or not. There are many alert messages to have to inspect in order to determine the network security situation. Also the much times are needed so that the network administrator can analyze the security condition using existing methods. Therefore, in this paper, we proposed an efficient method for analyzing network security situation using visualization. The proposed method monitors anomalies occurred in the entire IP address's space and displays the detail information of a security event. In addition, it represents the physical locations of the attackers or victims by linking GIS information and IP address. Therefore, it is helpful for network administrator to rapidly analyze the security status of managed network.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.138-147
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• 2003

There are some problems of current internet protocols to support the mobility of terminal in wireless environments. The mobile IP has come out to solve these problems, but there exists some problems like triangle routing, the need of each host's home address and the management of tunneling. Also. real-time multimedia traffics require fast hand-off, low latency and the utilization ratio of high bandwidth. SIP can support the mobility of wireless terminal and is widely accepted as the protocol which can support multimedia service and call setup in next generation network. In this paper, the framework of SIP system will be designed and implemented to support the mobility of wireless terminal by using JAIN API which follow the standards of next generation network and this system matches the standards of next generation network.

• Proceedings of the Korea Information Processing Society Conference
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• 2006.05a
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• pp.1235-1238
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• 2006

VoIP(Voice over IP)는 IP를 이용하여 음성과 데이터를 패킷 형태로 통합하여 실시간으로 전송하는 기술이다[1]. 본 논문에서는 VoIP망에서 리눅스 기반 IP 녹취 시스템을 설계 및 구현한다. 녹취 시스템은 고객과 상담원의 통화 내용을 자동으로 녹음하여 보관함으로써 고객의 요구 사항을 명확히 파악할 수 있다. 녹취 시스템으로 모든 네트워크 환경에서 사용할 수 있으며 CTI와 연동하여 효율적이고 체계적인 녹취 시스템 구축이 가능하다.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.11a
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• pp.1206-1209
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• 2007

IP-TV 서비스는 통신/방송 융합서비스로서 데이터 스트림이 송출되는 Server로부터 QoS가 보장되는 IP망을 통해 디지털 영상 방송이나 양방향 서비스를 가입자 단말까지 제공하는 서비스이다. IP-TV 서비스는 보안을 위해 CAS(Conditional Access System)를 사용하고, 또한 효율적인 콘텐츠의 전송을 위해 IP Multicast를 사용하게 된다. 보안 기능이 제공되지 않는 IP Multicast는 익명성을 허용하게 하여 eavesdropping, denial of service(DoS) Attack등이 가능하고, 또한 AAA(Authentication, Accounting, Authorization) 기능이 제공되지 않는다. IP-TV에서는 보안을 제공하기위해 Application 계층에서 CAS를 운용하게 되는데, 이는 Network계층에서 보안문제를 해결하는 것 보다 비효율적이다. 본 논문에서는 기존의 IGMP프로토콜을 확장, 개선하여 상호인증을 통해 CAS Server와 연계하여 IP-TV에 적합하게 만든 프로토콜을 제시함으로서, 이와 같은 문제점들을 해결하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.510-512
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• 2015

Recently, people fear is growing because of the various crimes that may occur when you go out. The growing is interest in security systems for the protection of an individual's property. In this paper, to establish a single central server based on the home network when intruders access to city, such as image processing values obtained through the IP camera and distance values disciplined use an ultrasonic sensor the user for an attacker city that will connect to the server the surveillance system provides the information that is received and implemented.

• The Transactions of the Korean Institute of Power Electronics
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• v.12 no.1
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• pp.19-26
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• 2007

This paper presents a precision position control of induction motor using disturbance observer to reduce disturbance effects. It shows that proposed algorithm is strong in induction motor precision control for disturbance change. This system with disturbance observer using deadbeat control, which has high benefit, is good for quick disturbance compensation. To show this effectiveness the whole process is simulated by simulink, and also experimented by DSP6416 with TCP-IP network board.