• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.4
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• pp.804-811
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• 1997

In the CDMA mobile communication system, reverse power control can be used to minimize the interference level for a good quality of the voice channel, and used to maxmize the system capacity. In this paper, we have analyed the environment of the K-parameter and the access procedure for the mobile station, and proposed a new algorithm for the access probe procedure of the station. K-parameter is determined according to the environment of the base station and access probe can adaptively control the power according to the position changes of the mobile station or the rapid and various state changes of the channel. Simulation results in the limited test environment show that it can increase the system capacity and decrease the power comsumption of the mobile station while maintaining the good and stable quality of the voice channel.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.19-22
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• 1998

In this study, the efficient channel coding method combined with CS-ACELP is proposed. The same convolutional coder and Viterbi decoder of COMA mobile communication system is used as channel coder. To make the best available use of limited channel coding redundancy, unequal error protection of punctured convolutional coder is used for variable reate allocation. But, the overall code rate is given by 2. The performance of proposed coder is analyzed and simulated in a Rayleigh fading channel. Experimental results show that the objective and subjective speech quality of variable rate channel coding methods are superior to those of non-variable channel coding method.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.74-77
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• 1998

We consider connection-oriented wireless cellular networks. These networks employ dedicated radio channels for the transmission of signaling information. A forward signaling channel is a common signaling channel assigned to carry the multiplexed stream of paging and channel allocation(virtual circuit allocation) packets from a base station to mobile stations. The delay levels experienced by paging and channel allocation packets have serious effect on the utilization level of the limited radio channel capacity. While a slotted mode operation is used to reduce the power consumption level at mobile stations, it may induce an increase in packet delay levels. In this paper, we thus consider a multiplexing scheme for paging and channel allocation packets under which slots are dynamically allocated for the paging packet transmission. For this dynamic scheme, we develop an analytical method for deriving the delay characteristics exhibited by paging and channel allocation packets, and investigate the effect of network parameters on the delay level by using this method.

• Journal of the Korean Operations Research and Management Science Society
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• v.41 no.1
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• pp.71-85
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• 2016

Service channel environments have changed dramatically with the advent of new, online digital channels. This article studies the effects of perceived multi-channel service quality on customer satisfaction and loyalty in the banking industry and the moderating role of age, which is a characteristic of customers. The objective is to identify the quality factors that affect the overall satisfaction and loyalty of a multi-channel customer. A quantitative study was conducted on 900 customers, with the main targets being users of the nine primary Korean retail banks. Results show that perceived service quality of the physical environment, human service, Internet banking, mobile banking, and ATM has a positive influence on overall satisfaction and loyalty. Age moderates the relationship among physical environment quality, human service, and customer loyalty.

• Electronics and Telecommunications Trends
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• v.37 no.3
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• pp.74-84
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• 2022

The Korean mobile service market has persistently grown with the number of subscribers and volume of mobile traffic. It shows the slow diffusion of 5G subscribers, and rapid growth of both the MVNO(Mobile Virtual Network Operator) market and unlocked mobile phones. Therefore, this study derives the direction of telcos' strategies and policy implications by empirically analyzing the usage and attitude of LTE and 5G subscribers. Our major findings are as follows: First, our current mobile service subscription market constitutes most long-term customers for their incumbent carriers only by device change from lock-in with bundle services. Mobile tariffs, data speed, and benefits of bundle services are important factors affecting choices and customers' satisfaction with a provider and intentions of churning to another. Second, demand and satisfaction for using 5G are less because speeds and service tariffs act as pain points for 5G services. Third, the users' high preferences for MVNOs and unlocked mobile phones are linked to their subscription to MVNOs' low-cost plans with unlocked mobile phones on online channels. These streams lead to a big change in the market competition that MNO(Mobile Network Operator)s' market shares are expected to decrease and MVNOs' shares will be increased by two times, in the near future. Therefore, MNOs need to change their distribution strategies from offline to online channels and try to resolve the stereotype, "mobile tariffs are expensive," by enhancing their service values. Finally, as consumers prefer one-stop service in the same channel regardless of the distribution channel, policies should focus on the consumers' needs for convenience rather than on the channel separation for perfectly unlocked mobile phones.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.7A
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• pp.623-631
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• 2010

In this paper, various of pilot-assisted channel estimation techniques for 3GPP LTE downlink are tested under multipath Rayleigh fading channel. At first, the conventional channel estimation techniques are applied with linear zero-forcing (ZF) equalizer, such as one dimensional least square (1-D LS) linear interpolation, two dimensional (2-D) wiener filter, the time and frequency dimension separate wiener filter and maximum likelihood estimator (MLE). Considering the practical implementation, we proposed two channel estimation techniques by combining time-dimension wiener filter and MLE in two manners, which showed a good tradeoff between system performance and complexity when comparing with conventional techniques. The nonlinear decision feedback equalizer (DFE) which can show a better performance than linear ZF equalizer is also implemented for mitigating inter-carrier interference (ICI) in our system. The complexity of these algorithms are calculated in terms of the number of complex multiplications (CMs) and the performances are evaluated by showing the bit error rate (BER).

• Journal of the Korean Society of Clothing and Textiles
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• v.35 no.12
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• pp.1425-1439
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• 2011

The present research developed and empirically examined a theoretical model called a Mobile Channel Extension Model for consumer behavior toward mobile commerce. We proposed three antecedents: compatibility of, subjective norm regarding, and media influence regarding mobile use for communication purposes that influence the attitude toward the subjective norm and media influences of mobile use for shopping. These in turn positively influenced the consume's intention to use mobile devices for shopping. A Structural equation modeling analysis, using the data collected from a national online survey of 524 U. S. multichannel shoppers, confirmed the proposed model. The theoretical implications of these effects were discussed and managerial suggestions were made for both academicians and practitioners.

• Journal of Broadcast Engineering
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• v.11 no.4 s.33
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• pp.521-532
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• 2006

Recently, many research initiatives have been underway to improve reception performance of ATSC based DTV signal in mobile channel by adopting multiple antennas. In this paper, we propose a new mobile channel model which can be applicable to any array geometry. And then we propose new channel estimation algorithm which uses PN5l1 sequence in field synch. The proposed algorithm is to estimate channel by correlating the input signal in If frequency band and finding maximum peak, which does not need complicated synchronization circuit. Finally, we propose new receiver structures which can be implemented at the front-end of the existing receiver with no modification. With computer simulation, we verify the performance of the proposed model and verify the performance of the receiver structure with computer simulation.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.5
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• pp.59-68
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• 1998

This paper proposes a neural network algorithm for a channel assignment in cellular mobile communications. The proposed algorithm is developed base on hopfield neural network in order to minimize the number of channel without a confliction between cells. To compare the performance of the proposed algorithm, we used seven benchmark problems selected from kunz's and funabiki's papers. Experimental results show that the convergence times are reduced form 27% to 66% compared with Kunz's and funabiki's algorithm and vonvergence rates are improved to 100%.

• Journal of Advanced Navigation Technology
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• v.18 no.3
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• pp.223-228
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• 2014

Recently mobile communication systems have supported various multimedia services based on wideband code division multiple access (WCDMA). In November 2013, the statistics reported that the domestic subscriber number of mobile communication systems was totally 54 million 514 thousand 397 in using feature phones and smart phones. Therefore, the user number of mobile communication services has surpassed over 4 million rather than the whole number of population. The sharp increase of the mobile user number has made the network management and analysis for mobile communication services more important than before. Besides, the service quality has been studied in various ways. This paper has implemented the simulator calculating the channel capacity of mobile communication systems to support secure and stable services for both feature phones on CDMA and smart phones on WCDMA. By using the simulator, this paper has analyzed the characteristics of the various channel capacity in mobile communication environments.