• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.4
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• pp.104-114
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• 2007

In this paper, an Ad-hoc Routing Protocol that works in wireless Ad-hoc communication networks with multiple radios and multiple channels and that controls call admission based on bandwidth measurement is proposed. Unlike the conventional Ad-hoc node with a single radio using a single channel, an Ad-hoc node of the protocol proposed, the MCQosR(Multiple Channel Quality of Service Routing), has multiple radios and uses multiple channels, which allows full duplex transmission between wireless Ad-hoc nodes, and reduces intra interference on the route. Also, a fixed channel only for reception at each node enables the estimation of the available bandwidth, which is used to control the call admission for QoS provision. The performance of the MCQosR was verified by simulation.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.121-128
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• 2010

Whenever and wherever, recognizing location of object such as human as well as things, ubiquitous Location-Based Service which provides useful service based on this are rising as an important service. In this paper, we implemented customized real time 1:1 e-CRM system that can communicate with user's mobile phone through using Location-Based Service of mobile phone. Among various scenarios that are applicable to designed system, development and test were conducted based on scenario that provides shopping information and discount information to customers through SMS as they approach to vicinity of large discount store and allow them to download discount coupons through Call Back. The suggested system will be applied to various service event and can be used as a customized real time marketing method according to user's personal activity area.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.2
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• pp.149-155
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• 2019

In this paper, we propose an emergency call system which makes a call to an institution or a guardian when an urgent case occurs to a user based on the indoor location service. In addition, it establishes indoor location service infrastructure assuming welfare institutions and hospitals. The proposed system receives the sensor value from the device that is in the form of a clock on the wrist and determines the emergency situation and delivers emergency information to the terminal. The location terminal transmits location and emergency information to the server, and the server accesses the database and stores the data. This enables the caregiver to communicate with the server through the application, monitor the user's status, receive notifications, and respond to emergency situations by using the emergency call function. If the proposed system is applied to the fields requiring urgent action such as medical field and welfare field, it will provide more stable and prompt emergency service to users and carers.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.10a
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• pp.27-30
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• 2003

The introduction of reseller In Australian Fixed Telecommunication Market resulted in the reduction of Telstra's local call market share by 13 percent and average fall rate was reduced. Thus, Telstra increased basic rate at 14.5 percent to compensate loss revenue in the local call market. With the deployment of carrier pre-selection of long distance and international calls, it reduced long distance rate at 23.5 percent and international tall rate at 53 percent, and increased the Churn rate. Therefore, the deployment of service-based competition brought efficient results for long distance and international call market. However, LM market created 13.4 percent reduction in call rates, complications in charge system, technical barriers and the preference of one-bill by customers.

• Journal of Internet Computing and Services
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• v.9 no.2
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• pp.139-145
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• 2008

CRM(Customer Relationship Management) improves the competitiveness of small companies to large enterprises. E-mail, SMS (Short Message Service), telephony service, DM (Direct Mail) are used for customer response in many companies. In order to improve company's profit, business diversification is in progress with protecting the succession of existing customers, and the only of new customers. Futhermore, BPR (Business Process Re-engineering) and BPM (Business Process Management) of the CRM can be easily found in many companies, because it is the first contact point to the company at the customer's view. This paper discusses the development of CRM, and proposes a call object routing agent that is the main engine of the CRM. Result of performance evaluation of proposed method show that the system is effective and powerful enough to use at the multi-channel environment.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.130-139
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• 2014

Due to the unpredictable nature of channel availability, carrying delay-sensitive traffic in cognitive radio networks (CRNs) is very challenging. Spectrum leasing of radio resources has been proposed in the so called coordinated CRNs to improve the quality of service (QoS) experienced by secondary users (SUs). In this paper, the performance of coordinated CRNs under fixed-rate with hard-delay-constraints traffic is analyzed. For the adequate and fair performance comparison, call admission control strategies with fractional channel reservation to prioritize ongoing secondary calls over new ones are considered. Maximum Erlang capacity is obtained by optimizing the number of reserved channels. Numerical results reveal that system performance strongly depends on the value of the mean secondary service time relative to the mean primary service time. Additionally, numerical results show that, in CRNs without spectrum leasing, there exists a critical utilization factor of the primary resources from which it is not longer possible to guarantee the required QoS of SUs and, therefore, services with hard delay constraints cannot be even supported in CRNs. Thus, spectrum leasing can be essential for CRN operators to provide the QoS demanded by fixed-rate applications with hard delay constraints. Finally, the cost per capacity Erlang as function of both the utilization factor of the primary resources and the maximum allowed number of simultaneously rented channels is evaluated.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1282-1289
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• 2000

In this paper we propose a Fractional Channel Reservation (FCS) scheme to satisfy a desired handoof dropping probability and to reduce the blocking probability of new calls using mobility characteristics and incoming handoff rate in mobile communication networks. When the ratio of the handoff call arrival rate is less then the ratio of the new call arrival rete, the proposed scheme is capable of determining the number of the guard channels which can guarantee the Quality of Service(QoS) in terms of the request handoff dropping probability and allocating dynamically the wireless channels the new calls according to the rest of the guard channels to reduce the new call blocking probability. Also we perform mathematical analysis and simulation to evaluate the performance of proposed scheme and compare to conventional guard channel scheme in terms of dropping probability blocking probability and the utilization efficiency of wireless channels.

• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.257-271
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• 2009

In this paper, we propose a protocol compression scheme for enhancing the performance of call processing of PTT(Push-to-Talk) which is one of the important services in IMS(IP Multimedia Subsystem), a next generation integrated wired/wireless packet communication network. To service the PTT on an IMS network, it should use the same call setup procedure as legacy Mobile and TRS(Trunked Radio System) networks and have a fast call setup time and enough communication bandwidth because a number of terminals should be able to exchange same data in real time. The proposed A+SigComp scheme reduces the initial call setup delay of SIP by about 10%, which is used by PTT service for call setup. In addition, the A+ROHC scheme is proposed to compress the header of RTP packets transferred during PTT voice transmission and, as a result, about 5% of increase in communication efficiency is observed.

• The KIPS Transactions:PartC
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• v.11C no.5
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• pp.613-620
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• 2004

Traditionally, simulation method was used to test and evaluate the performance of communication protocol or functional elements for mobile communication service. In this Paper, PCSsim(Personal Communication System Simulator) was realized that can evaluate and review the call process of mobile communication service or to predict its performance by using the object-oriented simulation platform. PCSsim can simulate the base station and mobile host by considering the user's mobility, call generation rate and call duration time. In this paper, based on the simulation, presented the simulation results of hand-off generation ratio according to call generation, user's moving speed and call duration time both in residence area and commercial area, and it was confirmed that the hand-off rates in simulation and actual service environment have similar features. PCSsim can be used in adjusting the characteristics of base station fellowing the dynamic hand-off buffering or the characteristics of user's call in the design stage, and also can be used in building new mobile communication network by reflecting the characteristics of region where the base station is located and the mobility of the user.