• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.243-248
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• 2012

In this paper we simulate the capacity of VOIP calls through WiFi network by computer simulations using OPNET modeler. The results show that sudden quality degradations occur on all VoIP calls when the number of call of an AP(Access Point) increases beyond a specific value. The reason of the quality degradation was turned out to be the queueing delay at the down link of AP. Under the IEEE 802.11b environments, the maximum number of VoIP calls of an AP maintaining the required voice quality (MOS > 2.5), was evaluated as 5, 12, and 27 when we use G.711, G.729a, and G.729a VAD codec, respectively.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.445-447
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• 2003

최근 무선네트워크의 급속한 확대로 무선인터넷 접속 또한 크게 증가하고 있다. 무선인터넷을 이용하는 Voice over IP 서비스는 IP 기반의 인터넷과 셀룰러 네트워크를 합쳐 놓은 것과 유사하며 모바일 노드의 이동성 확보가 핵심 기술이다. 특히 VoIP 서비스 이용자는 지연이나 끊어짐에 대하여 매우 민감하므로 가급적 지연시간이 적은 핸드오프 기법이 필요하다. 본 연구에서는 무선네트워크를 이용하는 VoIP 서비스 프로토콜 중 하나인 SIP를 기반으로 이동성 관리를 위한 신호의 흐름을 도시하여 발생 가능한 지연의 구성요소를 분석하였으며 핸드오프 지연을 줄이기 위한 Prediction Shadow Registration을 제안하였다.

• Electronics and Telecommunications Trends
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• v.17 no.2 s.74
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• pp.7-17
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• 2002

오늘날 대부분의 신기술은 통신규제를 우회하므로, 각국 정부는 규제를 포기하고 기술과 시장이 통신업종의 발전을 지향하는 방향으로 나아가고 있다. 그러나, IP Telephony와 관련된 최근의 동향은 기존의 법률과 규제가 각국에서 IP Telephony의 발전을 결정하는 강력한 요소임을 보여주고 있다. 본 고는 IP Telephony와 관련한 기술발전 추세와 표준화동향, 시장도입효과를 알아보고 특히, IP Telephony와 관련한 구체적인 도입방안을 위한 논의가 있었던 유럽연합과 프랑스를 중심으로 규제동향을 살펴보았다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.532-534
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• 2002

본 논문에서는 UDP／IP기반 SAN의 구현을 소개하였고 TCP／IP기반 SAN 및 로컬디스크와의 성능 비교를 통해 UDP／IP기반 SAN이 클러스터 웹서버에서 사용될 수 있는 가능성을 보였다. 실험결과 UDP／IP기반 SAN은 TCP／IP기반 SAN의 경우보다 약 20%정도 성능이 우수함을 볼 수 있다. 이는 UDP의 경우 TCP의 프로토콜 오버헤드가 없고 slow start의 영향을 받지 않으며 ACK를 기다릴 필요가 없기 때문이다.

• Convergence Security Journal
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• v.17 no.5
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• pp.11-18
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• 2017

Now the ways in which information is exchanged by computers are changing, a variety of this information exchange method also requires corresponding change of responding to an illegal attack. Among these illegal attacks, the IP spoofing attack refers to the attack whose process are accompanied by DDoS attack and resource exhaustion attack. The way to detect an IP spoofing attack is by using traceback information. The basic traceback information analysis method is implemented by comparing and analyzing the normal router information from client with routing information existing in routing path on the server. There fore, Such an attack detection method use all routing IP information on the path in a sequential comparison. It's difficulty to responding with rapidly changing attacks in time. In this paper, all IP addresses on the path to compute in a coordinate manner. Based on this, it was possible to analyze the traceback information to improve the number of traceback required for attack detection.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.1994-2005
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• 2015

Voice over IP (VoIP) is a technology for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks. Instead of being transmitted over a circuit-switched network, however, the digital information is packetized, and transmission occurs in the form of IP packets over a packet-switched network which consist of several layers of computers. VoIP Service that used the various techniques has many advantages such as a voice Service, multimedia and additional service with cheap cost and so on. But the various frauds arises using VoIP because VoIP has the existing vulnerabilities at the Internet and based on complex technologies, which in turn, involve different components, protocols, and interfaces. According to research results, during in 2012, 46 % of fraud calls being made in VoIP. The revenue loss is considerable by fraud call. Among we will analyze for Toll Bypass Fraud by the SIM Box that occurs mainly on the international call, and propose the measures that can detect. Typically, proposed solutions to detect Toll Bypass fraud used DPI(Deep Packet Inspection) based on a variety of detection methods that using the Signature or statistical information, but Fraudster has used a number of countermeasures to avoid it as well. Particularly a Fraudster used countermeasure that encrypt VoIP Call Setup/Termination of SIP Signal or voice and both. This paper proposes the solution that is identifying equipment of Toll Bypass fraud using those countermeasures. Through feature of Voice traffic analysis, to detect involved equipment, and those behavior analysis to identifying SIM Box or Service Sever of VoIP Service Providers.

• Electronics and Telecommunications Trends
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• v.17 no.5 s.77
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• pp.47-54
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• 2002

VoIP는 인터넷을 통한 음성 전화를 제공하는 기술이다. 유선의 PSTN과 인터넷간에 VoIP 기술을 적용하여 음성 전화를 제공한 데 이어, 이동통신 네트워크에서도 VoIP 기술에 의한 음성 서비스를 제공할 예정이다. 본 고에서는 유선 및 무선 통합 네트워크에서 VoIP 기술을 수용하기 위한 공통 논리 기능을 정의하고, 각 공통 논리 기능에 대한 IETF, ITU-T, 3GPP, 3GPP2 표준 규격의 기능 관계를 분석하여 유선, 무선, 인터넷의 통합 네트워크 구조를 제시하였다. 본 고에서 제시한 유선, 무선, 인터넷의 공통 논리 기능 구조는 유무선 네트워크를 통합할 수 있는 원천 기술 개발의 개념 구조로 사용할 수 있다.

• Review of KIISC
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• v.17 no.5
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• pp.57-65
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• 2007

초고속 인터넷의 보급 확산과 IT기술의 급격한 발전으로 우리 사회에서 인터넷 이용이 보편화를 넘어 필수적인 요소로 자리 잡고 있다. 이러한 현상에 따른 이용자 증가로 인해 최근 들어 패킷 망에 음성을 실어 보내는 VoIP(Voice Over Internet Protocol) 기술이 주목을 받고 있다. 이 기술로 인해 저렴한 통신비용 및 다양한 부가 서비스의 제공 가능성에 따라 새로운 비즈니스 모델이 증가할 것으로 예상되고 있다. 그러나 VoIP 서비스는 기존 인터넷망에서 발생할 수 있는 보안 취약성뿐만 아니라 인터넷 전화 트래픽 통과 문제 및 VoIP스팸이나 도청 같은 기존에 없었던 새로운 형태의 보안 이슈들이 많이 발생할 것으로 예상한다. 본 논문에서는 VoIP 신규 보안 위협을 분석하고, 분석된 보안 위협을 바탕으로 VoIP 공격 패킷 발생 도구를 구현하여 실제 공격 시 기존 보안 장비 시스템의 대응 여부에 대해서 기술하고자 한다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.3
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• pp.227-233
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• 2021

To obtain a fruitful outcome in intellectual property (IP) education in colleges, it is essential to identify the affecting factors. The relationships between the factors were to be analyzed as a structural equation model. The IP education achievement was measured by the IP total score. The students' characteristics (input factor) were measured by defining the characteristics, parents' expectations, and IP interest. The characteristics after highschool (process factor) were observed as college satisfaction and learning attitude. Students with excellent defining characteristics have not only high college satisfaction but also an excellent learning attitude, so they have a high IP total score. Using indirect effects analysis, the path through which the defining characteristics indirectly affects the IP total score through college satisfaction and learning attitude was identified. This is consistent with the prediction that self-directed students will have high participation in IP classes and achieve excellent results. The IP interest was found to have no significant effect on the IP total score. This contradicts the belief that students with high IP interest will actively participate in IP classes and earn high scores, which is because it overlooks the possibility that participation in IP activities in high school is semi-forced.

• Journal of Life Science
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• v.31 no.4
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• pp.410-417
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• 2021

Next-generation sequencing (NGS) is a high-throughput technique for sequencing large numbers of DNA fragments that are prepared from a genome. This sequencing technique has been used to elucidate whole genome sequences of living organisms and to analyze complementary DNA (cDNA) or chromatin immunoprecipitated DNA (ChIPed DNA) at the genome level. After NGS, the use of proper tools is important for processing and analyzing data with reasonable parameters. However, handling large-scale sequencing data and programing for data analysis can be difficult. The Galaxy platform, a public web service system, provides many different tools for NGS data analysis, and it allows researchers to analyze their data on a web browser with no deep knowledge about bioinformatics and/or programing. In this study, we explain the procedure for preparing chromatin immunoprecipitation-sequencing (ChIP-seq) libraries and steps for analyzing ChIP-seq data using the Galaxy platform. The data analysis steps include the NGS data upload to Galaxy, quality check of the NGS data, premapping processes, read mapping, the post-mapping process, peak-calling and visualization by window view, heatmaps, average profile, and correlation analysis. Analysis of our histone H3K4me1 ChIP-seq data in K562 cells shows that it correlates with public data. Thus, NGS data analysis using the Galaxy platform can provide an easy approach to bioinformatics.