• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.73-77
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• 2001

In this paper, we propose a virtual action system based on information agents, We call the system the MultiHammer, MultiHammer can be used for studying and analyzing online actions. MuiltiHammer provides functions of implement-ing a meta online action site and an experiment environ-ment. We have been using MultiHammer as an experiment as an experiment environment for BiddinBot. BiddingBot aims at assisting users to bid simultaneously in multiple online auctions. In order to bid simultaneously in multiple online auctions. In order to analyze the behavior of BiddngBot, we need to pur-chase a lot of items. It is hard for us to prepare a lot of fund to show usability and advantage of BiddingBot. MultiHam-mer enables us to effectively analyze the behavior of BiddingBot. MultiHammer consists of three types of agents for information collecting data storing and auctioning. Agents for information wrappers. To make agent work as wrarp-pers, we heed to realize software modules for each online action site. Implementing these modules reguires a lot of time and patience. To address this problem, we designed a support mechanism for developing the modules. Agents for data storing record the data gathered by agents for informa-tion collecting. Agents for auctioning provide online services using data recorded by agents for data storing. By recording the activities in auction sites. MultiHammer can recreate any situation and trace auction for experimentation, Users can participate in virtual using the same information in real online auctions. Users also participate in real auc-tions via wrapper agents for information collecting

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.879-888
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• 2000

In this paper, the performance of IS-95B CDMA system adopting multi-code scheme for data service on the forward link is obtained by theoretical analysis and computer simulation. The wireless channel is assumed to include AWGN, MUI(Multi-User Interference), and MPI(Multi-Path Interference), and multipath Rayleigh fading modeled by TDL(Tapped Delay Line). To obtain actual performance, IS-95B system using PN codes(M-sequence) concatenated with Walsh codes is considered. The BER performance of voice/data service satisfying QoS requirement and the maximum capacity of voice users is derived in terms of various system parameters(voice activity factor, required SNR of voice/data users, the number of multi-codes, the number of voice/data users.,etc.). As a result, under the condition that the maximum allowable number of voice user is 38 in voice only system, as the number of multi-code is decreased by 1, the maximum allowable number of voice user is increased by 5% for system with 1 data user and 22.3% for system with 4 data users. Therefore, it is possible to increase maximum allowable number of users in IS-95B CDMA system by appropriate control of the number of multi-codes and required SNR according to channel environment and traffic characteristic.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.145-148
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• 2000

This paper presents the performance of a GHICW(Group-wise Hybrid Interference Cancellation scheme based on Wiener filtering) receiver for the multi-rate DS-CDMA system. Our scheme has a small processing delay and a simple hardware complexity compared to ordinary interference cancellation schemes by grouping users with the same date rate. The performance improvement of the low rate user is obtained by using a Wiener filter which precisely estimates the high rate users' bit.

• Korean Management Science Review
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• v.21 no.3
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• pp.39-54
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• 2004

This paper presents a multi-agent system for intelligent recommendation of travel plans to users. The goal of the system is to provide alternative and preferable travel plans to users when the availability of tickets is low such as in vacations, holidays, weekends, or peak seasons. The multiple agents in the system search for available alternatives for a target travel in collaboration with other agents and recommend best alternatives by analyzing them using a multi-criteria decision-making model. A prototype online travel support system was constructed and a simulation experiment was performed for evaluation and comparison with different travel planning strategies.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.161-164
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• 2006

The sales of consumer durables are composed of first time purchases and replacement purchases. Since the sales for most mature durable products are dominated by replacement sales, it is necessary to develop a model incorporating replacement component of sales in order to forecast total sales accurately. Several single product diffusion models incorporating replacement demand have been developed, but research addressing the multi-product diffusion models has not considered replacement sales. In this paper, we propose a model based on consumer choice behavior that simultaneously captures the diffusion and the replacement process for multi-product relationships. The proposed model enables the division of replacement sales into repurchase by previous users and transition purchase by users of different products. As a result, the model allows the partitioning of the total sales according to the customer groups (first-time buyers, repurchase buyers, and transition buyers), which allows companies to develop their production and marketing plans based on their customer mix. We apply the proposed model to the Korean automobile market, and compare the fitting and forecasting performance with other Bass-type multi-product models.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1C
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• pp.22-27
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• 2011

This paper proposes an efficient user selection algorithm that provides a maximum 셀 용량 based Multi-user MIMO system based on zero-forcing criterion. The proposed scheme forms a primary group of users whose channel power exceeds a predetermined threshold. Through computer simulations, we have found that the proposed method outperforms the conventional scheme yielding a sum rate that is 0.33 bps/Hz higher when the total numbers of users and transmit antennas in the cell are 100 and 4, respectively.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.10
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• pp.1-8
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• 1997

In this paper, we propose a call admission control scheme which can be used in real environment for the traffic cibtrik if a base station if DS-CDNA cellular systems. The proposed scheme estimates the mean and variance of other cell interference by using the values used for the closed loop power control. The reerse link capacity of the base station can be calculated by using the estimated mean and variance of other cell interference. The base station admits a call only if the number of users is less than the calculated reverse link capacity. In addition, we propose a simple method to obtain the equivalent number of voice call users per one data call user in multi-rate traffic environment. The method can be applied to call admission control in multi-rate traffic environment.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.155-161
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• 2014

Mobility can lead to continual loss of data and service interruptions during communications in multi-hop cognitive radio networks. Mobility of primary users (PUs) or cognitive users (CUs) requires adjustment of multi-hop communications among CUs to avoid any interference to PUs. To provide durable and reliable data routing that ensures continuous network service, we propose mobility-aware cognitive routing (MCR) for multi-hop cognitive radio networks. MCR examines the risk level of each node against interference regions and selects the most reliable path for data delivery using a Markov predictor. Through simulation, we verify that the proposed scheme can avoid route destruction preemptively and achieve reliable data delivery.

• Journal of Communications and Networks
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• v.18 no.3
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• pp.439-445
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• 2016

In this paper, we consider subcarrier-index modulation (SIM) for precoded orthogonal frequency division multiplexing (OFDM) with a few activated subcarriers per user and its generalization to multi-carrier multiple access systems. The resulting multiple access is called sparse index multiple access (SIMA). SIMA can be considered as a combination of multi-carrier code division multiple access (MC-CDMA) and SIM. Thus, SIMA is able to exploit a path diversity gain by (random) spreading over multiple carriers as MC-CDMA. To detect multiple users' signals, a low-complexity detection method is proposed by exploiting the notion of compressive sensing (CS). The derived low-complexity detection method is based on the orthogonal matching pursuit (OMP) algorithm, which is one of greedy algorithms used to estimate sparse signals in CS. From simulation results, we can observe that SIMA can perform better than MC-CDMA when the ratio of the number of users to the number of multi-carrier is low.

• Journal of Information Processing Systems
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• v.17 no.2
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• pp.426-439
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• 2021

To alleviate the cold-start problem and data sparsity in web service recommendation and meet the personalized needs of users, this paper proposes a personalized web service recommendation method based on a hybrid social network and multi-objective immune optimization. The network adds the element of the service provider, which can provide more real information and help alleviate the cold-start problem. Then, according to the proposed service recommendation framework, multi-objective immune optimization is used to fuse multiple attributes and provide personalized web services for users without adjusting any weight coefficients. Experiments were conducted on real data sets, and the results show that the proposed method has high accuracy and a low recall rate, which is helpful to improving personalized recommendation.