• 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.

• Journal of Digital Contents Society
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• v.13 no.4
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• pp.477-482
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• 2012

The mVoIP service is the technology which focuses on the wireless data service as the IP network having the transmission rate of 100 Mbps classes on the high-speed middle of movement through the WiFi, WiBro and 3G mobile radio communication network, and etc. and is developed. Since 2010, the mVoIP (mobile VoIP) service shows the rapid growth due to 4G-LTE service seriously disclosed from July with the Smart phone and 2,011 it begins to be rapidly popularized. In this research, additionally the mVoIP service industry activation plan is presented with the trends of technology development including the chip-set/module/terminal, etc. based upon local and foreign market trend searchlight through the market demand analysis. The mVoIP service downloads App to the mobile apparatus and or can provide the service as the software through the WiFi network. Therefore, the change which is large in the products development aspect is to be have no. Expected to is being provided as the added service in the case of 4G-LTE as a matter of course, the service deployment where it is based on the market principle and demand needs is needed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.750-752
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• 2010

MANET has some interest as a wireless mobile network supporting node mobility and having no additional infrastructure. Speed of mobile node on MANET is various from just slow speed of human's walk to vehicle's moving speed. In this study, VoIP performance of MANET is evaluated in the view of speed of mobile node. VoIP performance is studied on walking speed, vehicle speed and higher speed on MANET. PDR(Packet Delivery Ratio), MOS(Mean Opinion Score) are used as performance parameters.

• The KIPS Transactions:PartC
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• v.18C no.3
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• pp.143-150
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• 2011

The adoption of VoIP is continuously increasing in public institutions, private enterprises and households due to cheaper cost and various supplementary services. Also, it is expected to spread widely the use of VoIP in mobile environment through the increasing use of smartphone. With the growing concern over the incidents of VoIP service while the VoIP service has become increasingly. Especially eavesdropping, it is possible to invade user privacy and drain the secret of company. So, it is important to adopt the protocols for VoIP secure communication. VoIP security protocols are already adopted in public institutions, but it is not adopted in private enterprises and households. In addition, it is necessary to verify whether the VoIP security protocol could be adopted or not in mobile VoIP due to its limited computing power. This paper compared the VoIP security protocol under fixed network and mobile network through performance evaluation. Finally, we found that it is possible to adopt the VoIP security protocols in mobile network.

• 한국경영정보학회:학술대회논문집
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• 2007.06a
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• pp.911-915
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• 2007

Mobile VoIP(이하 m-VoIP) 서비스의 도입에 따른 이동통신 사업자에게 미치는 영향을 크게보면 음성통화 서비스의 요금정책의 영향, 상호접속제도의 영향 그리고 음성통화 수익성에 영향으로 나누어 생각해 볼 수 있다. 본 논문에서는 m-VoIP 도입에 따른 이통사의 수입변화를 분석함으로서 그 영향력을 파악 하였다. 분석방법은 이통사의 수입을 접속료 수입과 음성통화 수입으로 나누고, 각각의 손실분 및 이익분을 추산해보는 방법을 사용 하였다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1109-1116
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• 2010

In this paper, some performance characteristics of VoIP(Voice over Internet Protocol) for MANET(Mobile Ad-hoc Networks) with simulation is studied and appropriate condition for implementation of VoIP service is suggested. VoIP simulator is implemented with NS(Network Simulator)-2. VoIP traffic for simulation is generated with some codecs of G.711, G.723.1, G.726-32, G.729A, GSM.AMR and iLBC. As simulation results for traffic transmission under $670{\times}670m$ 50node MANET environment, performance data for MOS(Mean Opinion Score), network delay, packet loss rate and transmission bandwidth are measured. Normalized analysis about measured results shows that maximum VoIP connection satisfying VoIP service quality condition is 15.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3238-3246
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• 2013

The progress of Information Technology enables people can communicate each others using the Internet. As a smartphone proliferates, many free mobile VoIP(Voice over IP) application are developed and accepted by smartphone users. In this study we investigate the factors affecting the acceptance of mobile VoIP applications and the structural relationship among these factors. We review the related works and extract the related factors and build a research model describing the causal relationship among these factors. We conduct an empirical study - a survey and statistical analysis - to verify the research model. EFA(Exploratory Factor Analysis) is applied for variables in the survey and SEM(Structural Equation Model) is used to reveal the structural relationship among the factors. We can find that two factors - usefulness of mobile VoIP and social influence - positively affect usage intention and actual use. These findings imply that it is required to emphasize the benefits of mobile VoIP use and add S/W functionalities enhancing social influence.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.795-797
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• 2009

Voice over Internet Protocol(VoIP) service becomes more and more popular nowadays. As such, it is developed over many kinds of network models, especially wireless networks. Mean Opinion Score(MOS) computes the QoS of VoIP service which should be supported by robust network environment. However, MANET is not stable enough to supply high MOS values for VoIP service. In this paper, VoIP service over MANET is simulated using ns-2(Network Simulation 2). In oder to get different MOS values in the results, we differentiate between network environments by adjusting the parameters of MANET.Through comparing the results we can know how to improve the QoS.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.89-92
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• 2001

In this paper, it is proposed that RSVP and WFQ must be a good way of a better service for the better quality for Mobile If Network. For the Performance Analysis of working it was composed of Mobile IP and VoIP Network model, and further more test of the postpone and QoS was implemented. The results of the test is as follows, Before the movement of mobile agent was 2ms, after that, 3ms, And before QoS was adapted the value was 30ms, after being adapted, analyzed as 10ms. This research that the problem of put off was improved by adaping QoS in the mobile IP Network.

• Electronics and Telecommunications Trends
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• v.21 no.2 s.98
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• pp.66-73
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• 2006

PC-to-PC 또는 PC-to-Phone에서 구현되었던 초기 VoIP 서비스의 낮은 음성 품질은 기존 유선 전화서비스와 경쟁이 되지 않는 것으로 인식되었고 규제의 대상에서 제외되었다. 그러나 기술의 발전에 따라 향상된 품질의 음성서비스 및 다양한 응용서비스 등을 저렴한 가격에 제공할 수 있게 되었으며, 식별번호의 부여를 통해 VoIP 서비스는 기존 음성전화서비스와 동등한 수준의 경쟁력을 확보할 수 있는 것으로 평가되어, 기간통신서비스로서 기존 음성전화서비스와 유사한 수준의 규제를 받게 되었다. 최근에는 이러한 VoIP 서비스가 유선 환경에서뿐만 아니라 무선 LAN 환경에서도 구현되었고, 나아가 VoWLAN과 이동전화를 묶음으로 제공하는 기술이 가능하게 되었으며, 궁극적으로 VoIP가 이동전화서비스와 같이 완전한 이동 환경에서의 구현이 멀지않은 것으로 전망되고 있다. 이에 따라 무선 또는 이동 환경에서의 VoIP 서비스에 대한 이슈가 수면 위로 부상할 전망이며, 특히 이동 환경은 기존 이동전화사업자의 주파수 할당대가 납부 등의 측면에서 유선 환경과는 다소 차이가 있으므로 이동 환경에서의 VoIP를 어떤 식으로 규정해야 될지에 대해 많은 논란이 일 것으로 예상된다.