• Proceedings of the Korean Information Science Society Conference
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• 2011.06d
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• pp.135-136
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• 2011

The more VoIP service is widely used, the more VoIP spam becomes threatened. Both VoIP spam violates the user's privacy and VoIP spam can cause money trouble. Therefore, it is important to reduce the VoIP spam but it is not easy to adopt some useful techniques to counter e-mail spam due to VoIP characteristics. We propose a technique using VoIP-RBL for countering SIP-based VoIP spam.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.421-426
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• 2004

According to explosive increasing of internet users, efforts and competitions for development of internet industry has been accelerated. In recently the VoIP service is on the rise with the best interesting field among the present internet application services. In this paper, we proposed a desirable VoIP service activation plan in the cases of technic, politcy and so on by considering on VoIP service and current VoIP service problems.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.5 no.3
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• pp.110-116
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• 2012

As rapid development of the Internet, there are increasing interests about quality of service of VoIP using the Internet network and established PSTN. There was some study going on to improve the quality of service from the point of view of supplier's mainly. However recently, the demand for setting up the objective standards that service provider can offer to customers is needed as the interests from customers has been going up. In this study, we analysed the results from the test using PESQ which is a parameter of quality of service. we offer the conditions of network which guarantees the minimum quality of phone call using VoIP.

• Journal of the Korea Society for Simulation
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• v.16 no.3
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• pp.75-87
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• 2007

As the VoIP service quality is getting better and many shortcomings are being overcome, users are getting interested in this service. Also, there are several additional features that provide a convenience to users such as presence service, instant messaging service and so on. But, as there are always two sides of rein, some security issues have users hesitate to make use of it. This paper deals with one of the issues, the VoIP spam problem. We took into account the signal pattern of voice message in spam call and we have constructed voice signal models of normal call, normal call with noise and spam call. Each voice signal case is inserted into our spam decision algorithm which detects the spam calls based on the amount of information in the call signal. We made use of the DEVS-$Java^{TM}$ for our modeling and simulation. The contribution of this work is in suggestion of a way to detect voice spam call signal and testing of the method using modeling and simulation methodology.

• Journal of Digital Contents Society
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• v.12 no.1
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• pp.85-94
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• 2011

QoS(Quality of Service) is defined as "The collective effect of service performance which determines the degree of satisfaction of a user of the service" by ITU-T Rec. E.800. While the use of VoIP(Voice Over Internet Protocol) has been widely implemented, persistent problems with QoS are a very important sue which needs to be solved. This research is finding the assignment of VoIP QoS to deduct how to manage the control system and presenting the QoS control process and framework under NGN(Next Generation Network) environment. The trial framework is the modeling of the QoS measurement metrics, instrument, equipment, method of measurement, the series of cycle & the methodology about analysis of the result of measurement. This research underlines that the vulnerability of the VoIP protocol in relation to its QoS can be guaranteed when the product quality and management are controlled and measured systematically. Especially it's very important time to maintain the research about VoIP QoS measurement and control because the big conversion of new network technology paradigm is now spreading. In addition, when the proposed method is applied, it can reduce an overall delay and can contribute to improved service quality, in relation to signal, voice processing, filtering more effectively.

• The KIPS Transactions:PartC
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• v.14C no.6
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• pp.481-492
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• 2007

The ubiquitous environment allows users to communicate with others and to have access to computing service any time, any place. Multipoint VoIP is expected to be one of the loading applications in this environment. The paper compares various conference models for efficient VoIP service in ubiquitous environment and shows why the endpoint mixing model performs effectively in this environment. However, the endpoint mixing model has its own drawbacks as well and we propose solutions to solve the problems.

• Proceedings of the Korea Contents Association Conference
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• 2004.11a
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• pp.125-128
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• 2004

Although the current VoIP service is limited within the wire network, the future network will be a united network of wire/wireless. It is required that the study on the granting plan of numbering system by not considering the simple VoIP service but considering the entire network of wire/wireless. In this paper, we proposed a desirable VoIP service activation plan in mobile network suited to the future network by considering on VoIP service and mobile VoIP service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.387-393
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• 2009

In this paper, we have considered the network performance of the VoIP service with the measurement by an emulator, and analyzed the major factors to affect its performance. Also, we have used the measured values to investigate the traffic variations, where their values were observed in the commercial operated network after the delay, jitter and packet loss, and loss compensation methods were applied as the dominant elements. It is expected that our presented results will be a good data to provide the high-quality of voice service in the Internet.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.3
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• pp.261-265
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• 2008

As increasing the user of VoIP service using ITSP(Internet Telephony Service Provider), the VoIP spam becomes a big problem. The spam used in the existing public telephone is detected by using the pattern inspection of call behavior because it is difficult to filter contents for the characteristic of real-time voice communication. However there is a false-positive problem. The threat on spam remains where spam with low threshold can't be detected or users share one number. In this paper, we propose anti-spam for VoIP based on luring test. The proposed method gives a user luring test and he/she can connect to a receiver if passing turing test. A ticket is given to a user that pass luring test and it reduces overhead of luring test in re-dial. The proposed method is implemented on ASUS WL-500G wireless router and Asterisk IP-PBX. Experimental results show the effectiveness of the proposed method.

• The Journal of the Acoustical Society of Korea
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• v.28 no.2E
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• pp.35-42
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• 2009

In this paper, we present criteria of objective measurement of speech quality to provide the mobile-VoIP services efficiently over wireless mobile internet. The mobile-VoIP service, which is based on mobility and is error-prone compared to conventional VoIP over wired network, is about to be launched, but there have not been adequate quality indexes and the Quality of Service (QoS) standards for evaluating speech quality of Mobile-VoIP. In addition, there are many factors influencing on the speech quality in packet network of which packet loss contribute directly to the overall voice communication quality. For this reason, we adopt the Gilbert-Elliot Channel Model for modeling packet network based on IP and assess the voice quality through the objective speech method of ITU-T P. 862 PESQ and ITU-T P. 862.1 MOS-LQO under various packet loss rates in the transmission channel environments. Our simulation results address the specific criteria and QoS for the mobile-VoIP services in terms of the various packet loss environments.