• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.8A
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• pp.743-751
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• 2010

OFDMA femtocell becomes an effective solution to support indoor high data rate services instead of the macrocell systems. Although the advantage of the femtocell, the co-channel interference between the femocell and the macrocell is the most significant problem that reduces the system performance. Macrocell users who have no permission to access the femtocell suffer from interference of the downlink transmission of femtocell. Therefore, the femtocell should use transmission power as small as possible to reduce interference to macrocell users. In this paper, we define the margin adaptive power allocation problem for the femtocell and propose a heuristic power allocation algorithm to solve the problem. Simulation results show the performance of the proposed algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1132-1136
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• 2005

In this paper, adaptive equalizer receiver for a turbo code direct sequence code division multiple access (DSCDMA) by using least mean square (LMS) adaptive algorithm is presented. The proposed adaptive equalizer is using soft output of decision feedback adaptive equalizer (DFE) to examines the output of the equalizer and the Log- maximum a posteriori (Log-MAP) algorithm for the turbo decoding process of the system. The objective of the proposed equalizer is to minimize the bit error rate (BER) of the data due to the disturbances of noise and intersymbol interference (ISI)phenomenon on the channel of the DS-CDMA digital communication system. The computer program simulation results shown that the proposed soft output decision feedback adaptive equalizer provides a good BER than the others one such as conventional adaptive equalizer, infinite impulse response adaptive equalizer.

• IEIE Transactions on Smart Processing and Computing
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• v.3 no.4
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• pp.181-190
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• 2014

This paper reports a cognitive radio network architecture based on overloaded multicarrier direct sequence code division multiple access (O-MC-DS-CDMA). The O-MC-DSCDMA technique combines CDMA with a multicarrier modulation technique to overcome the channel fading effects. In this technique, secondary users are enabled to share the available bandwidth with the existing primary users. Two sets of orthogonal Gold codes are used to support the primary and secondary users simultaneously. The orthogonality between the spreading codes is lost due to the non-zero cross correlation between the codes and the timing synchronization error in the uplink transmission, which causes interference between primary and secondary users. This paper proposes two modified hybrid parallel/successive interference cancellation techniques for primary and secondary user base station receivers with multiple antennas to suppress the interference among users. Interference among the same group of users is cancelled by parallel interference cancellation and the interference among groups is cancelled using successive interference cancellation. The simulation results confirmed that the proposed modified interference cancellation techniques show better BER performance over conventional interference cancellation techniques.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.1
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• pp.17-23
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• 2007

The home network has been revitalized due to the emergence of the high-speed broadband network and explosive increases of the home network services. Especially multicast based high-definition (HD) IPTV service is on high demand from both Internet service provider (ISP) and users. In order to provide high quality HD IPTV service without packet loss and delay, the ISP utilizes various network QoS mechanisms. Due to the misleading fact, that the home gateway is considered as an end terminal in terms of the ISP's viewpoint, the ISPs can not guarantee the end-to-end QoS within the scope of the current home network architecture. Therefore, an independent QoS guaranteed mechanism should be considered within the home network domain. As the home gateway manages both private home and public access network within the home network, we propose and implement a novel QoS mechanism for the multicast based HD IPTV service over the home gateway. In order to provide QoS guaranteed HD IPTV service, the proposed mechanism classifies the packets, manages home network bandwidth resources, and executes call admission control using the channel join message. Also, we utilize layer 2 multicast packet forwarding scheme to improve the overall performance of the home network services. Through the experiments of implementing the multicast based HD IPTV services, we will verify the efficiency of the proposed mechanism.

• Nuclear Engineering and Technology
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• v.52 no.8
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• pp.1603-1610
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• 2020

Due to ever-growing advancements in computers and relatively easy access to them, many efforts have been made to develop high-fidelity, high-performance, multi-physics tools, which play a crucial role in the design and operation of nuclear reactors. For this purpose in this study, the neutronic Monte Carlo and thermal-hydraulic sub-channel codes entitled MCNP and COBRA-EN, respectively, were applied for external coupling with each other. The coupled code was validated by code-to-code comparison with the internal couplings between MCNP5 and SUBCHANFLOW as well as MCNP6 and CTF. The simulation results of all code systems were in good agreement with each other. Then, as the second problem, the core of the VVER-1000 v446 reactor was simulated by the MCNP4C/COBRA-EN coupled code to measure the capability of the developed code to calculate the neutronic and thermohydraulic parameters of real and industrial cases. The simulation results of VVER-1000 core were compared with FSAR and another numerical solution of this benchmark. The obtained results showed that the ability of the MCNP4C/COBRA-EN code for estimating the neutronic and thermohydraulic parameters was very satisfactory.

• Journal of the Korea Fashion and Costume Design Association
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• v.5 no.2
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• pp.31-46
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• 2003

The purpose of this study was to explore the ways of improving Korean apparel firms' competitiveness by examining the Korea's number one trading partner U.S. apparel industry. Especially, the Los Angeles area apparel industry which is the second largest and the primary market center on the west coast was analysed. The following strategies are suggested to Korean apparel firms to function more effectively in incleasingly competitive U.S. markets: l)Basics can be produced in lower wage countries meanwhile quick turnaround and high quality works can be produced either in Korea or U.S. 2)Manufacturers might try to have direct relationship with powerful retailers who have their own private labels of store-brand lines. 3)Apparel companies can open market showrooms in the California Market Center. For small firms they can contact with independent representatives who receive commissions for showing lines for manufacturers or rent space for showing the lines during market weeks. 4)Apparel firms can contact buying offices to introduce their products to retail buyers. 5)Korean firms can contact Korean-American apparel firms to gain easy access to U.S.Market.

• Journal of Information Technology Applications and Management
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• v.15 no.1
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• pp.261-270
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• 2008

Wireless Mesh Networks (WMNs) have emerged as one of the new hot topics in wireless communications. WMNs have been suggested for use in situations in which some or all of the users are mobile or are located in inaccessible environments. Unconstrained transmission in a WMN may lead to the time overlap of two or more packet receptions, called collisions or interferences, resulting in damaged useless packets at the destination. There are two types of collisions; primary collision, due to the transmission of the stations which can hear each other, and hidden terminal collision, when stations outside the hearing range of each other transmit to the same receiving stations. For a WMN, direct collisions can be minimized by short propagation and carrier sense times. Thus, in this paper we only consider hidden terminal collision while neglecting direct collisions. To reduce or eliminate hidden terminal collision, code division multiple access (CDMA) protocols have been introduced. The collision-free property is guaranteed by the use of spread spectrum communication techniques and the proper assignment of orthogonal codes. Such codes share the fixed channel capacity allocated to the network in the design stage. Thus, it is very important to minimize the number of codes while achieving a proper transmission quality level in CDMA WMNs. In this paper, an efficient heuristic code assignment algorithm for eliminating hidden terminal collision in CDMA WMNs with general topology.

• International Commerce and Information Review
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• v.11 no.1
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• pp.177-197
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• 2009

In this study we presented the plans to activate the Internet Shopping Mall for GWmart under its present situation recording a rapid growth in sales and recognized as a local new distribution channel since its early stage, using the analysis that affects the purchases of consumers. On studying the reliance of a shopping mall, only the shopping mall image and the efficiency in providing information are significant. Regarding the concentration on the shopping site by shoppers, what becomes significant are the efficiency in providing information and the convenience in searching for products, which is one of the important factors in increasing sales, does not affect the reliance of a shopping mall and the concentration on the shopping site by shoppers. Therefore, this finding suggests that it is not easy to access the internet shopping mall when consumers go shopping for certain products. Because of this, it is necessary to change the design and structure of internet shopping mall to focus on the consumers. Moreover, this study showed that the efficiency in providing information to customers and the image of the shopping mall do not affect the consumers' intention to purchase, which means that shopping mall lacks in its information service and the management of its structure. To address this, it is required to advance the User Interface and contents of internet shopping mall.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.4
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• pp.759-764
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• 2009

A new backoff scheme for infrastructure mode in IEEE 802.11 wireless LANs is proposed to improve a performance. Each station generates a unique backoff number using total number of stations, fairness parameter included in beacon frame and an user's ID that is assigned by AP. The station sends a packet after its own backoff number of idle slots, which makes a collision free access among stations within AP's coverage. The proposed method shows better performance in the view of channel utilization and packet delay than an original IEEE 802.11 CSMA/CA backoff scheme.

• Journal of the Korean housing association
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• v.18 no.1
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• pp.1-10
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• 2007

This study aims to examine the way in which magazines represent housings, since magazines are one of major channel to connect individual houses with the public including professionals and the mass as well. Not only the professional architectural magazine but also women's magazine produce discourses which exercise huge influences on the public's understanding of the housings. After examining the different ways of representing housings in the houses related articles of architectural magazine and women's magazine, serious discrepancies have been noticed in both form and content of the text. In representing housings, women's magazine uses headlines and standfirsts with various modifiers to enhance the chance of interventions of the magazine/journalists. Focusing of the interests upon residents and architects, women's magazines force the reader to look at the housings through the frame of social status and celebrity of the residents and architects marginalizing actual houses. On the other hand, architectural magazines adopt externalized and objective way of representation using minimum layout elements following relatively uniform editing format. The abstract, rigid and masculine way of representation in the architectural magazines endow the published housings with the masculine and normative senses which can be seen as some sorts of aura which obstruct easy access to the housings themselves.