• The Journal of the Acoustical Society of Korea
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• v.28 no.3E
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• pp.99-108
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• 2009

In this paper, we suggest criteria for objective measurement of speech quality in mobile VoIP (Voice over Internet Protocol) services over wireless mobile internet such as mobile WiMAX networks. This is the case that voice communication service is available under other networks. When mobile VoIP service users in the mobile internet network based on packet call up PSTN and mobile network users, but there have not been relevant quality indexes and quality standards for evaluating speech quality of mobile VoIP. In addition, there are many factors influencing on the speech quality in packet network. Especially, if the degraded speech with packet loss transfers to the other network users through the handover, voice communication quality is significantly deteriorated by the transformation of speech codecs. In this paper, we eventually adopt the Gilbert-Elliot channel model to characterize packet network and assess the voice quality through the objective speech quality method of ITU-T P. 862. 1 MOS-LQO for the various call scenario from mobile VoIP service user to PSTN and mobile network users under various packet loss rates in the transmission channel environments. Our simulation results show that transformation of speech codecs results in the degraded speech quality for different transmission channel environments when mobile VoIP service users call up PSTN and mobile network users.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.293-300
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• 2007

As the development of the various IP-based services, it is expected that Internet telephony service will gradually replace the traditional PSTN-based telephony service. But there are many issues resolved to spread the Internet telephony service. One of them is to support the emergency services in the Internet telephony. In the case of USA, it has been regulated that 911 services should be supported in the Internet telephony services using VoIP on the similar performance level to PSTN 911 service. According to the regulation, basic VoIP 911 calls should be routed to the general access line of LEA without the location information or the callback number, but the enhanced VoIP 911 calls with the location information and callback number should be routed on the dedicated 911 network and destined to the local 911 distribution center such as PSAP. But, in the current VoIP-based Internet telephony network, the emergency call service has not been handled as one of the special services as well at has a worse performance in comparison to it on PSTN. Moreover, the service has a critical problem that it can not be destined to the nearest PSAP because of the insufficient information about the location information and the call back number. In this paper, we suggest the SIP-based emergency call service mechanism in order to resolve the problems above mentioned. This suggested mechanism is implemented to show its effectiveness and efficiency.

• The Journal of Korea Robotics Society
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• v.6 no.2
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• pp.147-155
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• 2011

This paper presents an edutainment robot for young children. The edutainment robot called 'Mon-e' has developed by the Central R&D Laboratory at KT. The main services of the Mon-E robot are autonomous moving service, object card and story book telling service and videophone service. The RFID technology was introduced for easy interface to young children. The face of Mon-E robot is mounted with an RFID reader. The RFID tag is pasted on story book and object card. If you approach a book or an object card to the face of Mon-E, the Mon-E robot recognizes the identified code and plays its service. In autonomous moving, if the Mon-E robot meets obstacles, it moves back and turns left or right or half rotation. In videophone service, if young children approach an RFID card to the Mon-E, the Mon-E can make a call to the specific number, which is contained in the RFID card. The developed Mon-E robot has tested in real world environment and is evaluated young children and their parents. In the result of evaluation, the feeling of satisfaction was high to main services of Mon-E robot.

• Journal of Korea Multimedia Society
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• v.1 no.2
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• pp.249-255
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• 1998

This paper analyzes the impact of Call Setup Time on UPT performance based on the AIN platform. Call Setup Time is used as the performance parameter. In implementing UPT based on the AIN platform, the geographical location of VLR affects network performance. In order to find an optimum location of VLR among three different types of structures, i.e. VLR is located close to Service Switching Point and Cell Site Controller and located at Service Control Point, each Call Setup Time on proposed time delay model is calculated and compared. Network performance is analyzed by changing the number of STP in No.7 signaling network in UPT and the utilization ratio, $\rho$, for SSP, STP and SCP.

• The Journal of Society for e-Business Studies
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• v.21 no.3
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• pp.51-78
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• 2016

Online-to-offline (O2O) commerce is the new trend that merges online commerce with traditional industries in various fields. The primary purpose of this paper is to find out which factors influence customers' intention to switch from call-based driver-for-hire services to O2O app-based services. This study used variables and factors based on Theory of Switching Intention, and Extended Unified Theory of Acceptance and Use of Technology in order to design research questions. We surveyed 500 users of call-based driver-for-hire services. According to the result of this study, dissatisfaction with the current call-based driver-for-hire services is estimated to be a significant factor that strengthens customers' intention to switch from the call-based driver-for-hire services to the app-based services. Loyalty to the previous call-based driver-for-hire services was not seen as a crucial motivator that causes customers to switch to the new O2O driver service. Switching cost also did not play a key role in explaining the relationship between dissatisfaction with the current call-based service and the intention to use the new app-based service. Performance expectancy, easiness in use, the level of user's knowledge or available assistance in relation to the use of app-based services, and expectancy for reasonable price was found to have meaningful impacts on customers' intention to switch from the call-based driver-for-hire services to the app-based services. Age, gender and user experience on the new service were found incapable of moderating the relationship between aforementioned factors which influence customers' choice of the app-based driver-for-hire service, and customers' intent to switch to the app-based service.

• The Journal of Korea Robotics Society
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• v.5 no.2
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• pp.93-101
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• 2010

This paper presents the system design and implementation of 'Mon-e', the KT's edutainment robot for young children. We paid our special attention to the computer- illiterate young children, and the provision of the physical and friendly human interface of robots. Specifically, the paper focuses on the video telephony and home monitoring service using the Mon-e robot. RFID cards -based calling makes it possible for the computer-illiterate children to make a phone call to their parents. The SIP and DTMF based remote control of the robot enables the search and track of the children. This experimental development shows the potentialities and values of the convergence service of telecommunication and robotics.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.7
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• pp.520-533
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• 2007

The CRM(Customer Relationship Management) is the business strategy model for higher profits and competitive power of the enterprise in a new business environment. The large-scale customer response service technique uses internet, e-mail, SMS (Short Message Service), Telephony service, DM(Direct Mail) by customer channel point. Recently, business model diversify for new contract and retaining existing customer to the effort for a profitable model of business. This paper is based on Avaya PDS(Predictive Dialing System) model for CRM bond center. If the number of "available" agents are less than the number of inbound channels, then there may be real-time response problems in PDS system implemented. The Organization cannot afford to have many agents in available mode because of the high cost of manpower. This paper provides two contributions to the study. First, we present Call Object Management Mechanism of Customer Channel integration for reduce outbound consulting and reduce CallBack data in the PDS. Second, we design and implement the proposed system. Our simulation results show analysis of old model and proposed model. The proposed model can be efficiently used in Large-scale CRM.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.5
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• pp.77-82
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• 2016

Web developers have had difficulties in using Rich Communication Service-e(RCS-e) on their applications because of complicated protocols and closed interfaces. In order to vitalize the use of RCS-e, we need a RCS Application Program Interface(API) which has simple protocols and can be accessed easily. This paper presents the web-based Open API Framework for the RCS-e presence feature. A system architecture for the framework is defined. Call flows for the presence feature between the framework and other nodes are defined. Also, one of the call flows is illustrated to explain how to convert web-based requests to RCS-e requests. Finally, performance evaluation proves that the framework does not add any loads to the existing network infrastructure.

• Journal of Korea Multimedia Society
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• v.17 no.5
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• pp.582-589
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• 2014

Mobile phone users have been using the SMS to send and receive text messages between them. Recently, GSMA(GSM Association) proposed the next generation instant messaging service, RCS-e(Rich Communication Service-enhanced). This was unavoidable because new OTT(Over The Top) services have emerged that threat the SMS after smart phones became popular. However, the RCS-e has limitations that it cannot inter-operate with the SMS which is still widely used. This paper propose a software framework that inter-work SMS with RCS-e. Call flows for canceling wireless contracts and sending SMS messages to RCS-e users were defined. Also, methods for protocol conversion were defined to inter-work two services. The performance evaluation showed that the proposed framework does not increase loads on IMS(IP Multimedia Subsystem) infrastructure.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.939-945
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• 2011

We show a new scheme and implementation of maritime data communication systems for GMDSS ship which performs e-Navigation and removes the functional limitation of those systems through comparing to service fee, call processing reliability, and bit rates of all of those systems within communication range at sea. We confirmed available each frequency band communication and application services at sea by experimental result with proposed new system, MF/HF band being useful to a short text message service, VHF band to 9600bps email service, Fleet Broadband Maritime Satellite system to one or more Mbps multimedia service each.