• Journal of the Institute of Convergence Signal Processing
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• v.17 no.1
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• pp.1-9
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• 2016

In this paper, for the improvement of quality of service(QoS) performance of heterogeneous networks, multi-cell scheduling is proposed. In order to implement the proposed algorithm, for the recognition of the impact on the throughput performance of users, macro-pico-cells that form distributed architecture were proposed. In operating heterogeneous networks, considering the centralized structure, a macro-RRH(Remote Radio Head) deployment scenario was proposed. For interference mitigation of the proposed system, by applying the optional sub-frame, through CQI(Channel Quality Indicator) measurement for each sub-frame period, constraint conditions were measured according to system situations. For the simplification, the pattern of the same ABS muting was assumed. In the above two multi-cell environments, the algorithm of high-speed load balancing maintenance was proposed.

• Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.9.1-9.7
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• 2018

To establish a comprehensive management strategy, as part of the optimization of cultural practice for an oyster rack culture system, we used a numerical model to estimate the primary production in the waters on the eastern coast of Wando island, South Korea. The estimated primary production ranged from 17.12 to $1052.55mgC\;m^{-2}day^{-1}$ ($204.22{\pm}224.75mgC\;m^{-2}day^{-1}$ in average). Except for the times of peak phytoplankton blooms, the estimated primary production (PP) was consistently under $200mgC\;m^{-2}day^{-1}$, which is more similar to the value of PP measured off the western coast of South Korea than the southern coast. No clear relationship was observed between nitrogen content and rainfall with the exception of heavy rainfall events, indicating that precipitation might not be the main source of nutrients in these waters. No clear influence was observed from Doam tidal discharge, located 24 km north from these waters due to main tide comes in this area from the channel between Gunwe-myeon in Wando island and Pukpyeong-myeon in Haenam-gun. Because of the shallow water depth and strong tidal current, resuspension of sediments, which causes an input of nitrogen into the system, could be easily caused by even mild wind and the infrequent passing of ships. Microscopic examination of the phytoplankton composition showed additional contribution of benthic species such as Paralia sulcata into the waters, which increase the productivity of oyster farms in the waters. The availability of nitrate and phosphate for primary production was temporarily limited throughout most of the spring and autumn blooming season.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8B
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• pp.514-524
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• 2005

In optical burst switching(OBS) networks, the ingress edge router assembles packets in the same class queue into the appropriate size of burst. A burst control packet(BCP) is generated for channel reservation of corresponding data burst and sent earlier than the corresponding data burst with an offset time. Offset time is determined considering the number of hops from source to destination and the required quality of service(QoS). After offset time, the burst data is passed through tile pre-configured optical switches without any O/E/O conversion. But a failure in OBS networks may lead to the loss of bursts until the ingress nodes receive the failure indication signal. This results in a significant degradation in QoS. Therefore, in this paper, we propose a fault-tolerant node architecture based on sub-carrier multiplexing to reduce the effects of failure in OBS networks. The Performance of the proposed fault-tolerant node architecture exhibits considerable improvement as compared with the previous ones.

• Journal of the Korea Society of Computer and Information
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• v.13 no.4
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• pp.133-140
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• 2008

The cable TV network has delivered downward broadcasting signals from distribution centers to subscribers. Since the traditional coaxial cable has been upgraded by the Hybrid Fiber Coaxial(HFC) cable, the upward channels has expanded broadband services such as Internet. This upward channel is vulnerable to ingress noises. When the noises from the children nodes accumulated in an amplifier exceeds a certain level, that node has to be cut off to prevent the noise propagation. The node selection problem(NSP) is defined to select nodes so that the noise in each node does not exceed the given threshold value and the sum of Profits of selected nodes can be maximized. The NSP has shown to be NP-hard. In this paper, we have proposed heuristics to find the near-optimal solution for NSP. The experimental results show that interval partitioning is better than greedy approach. Our heuristics can be used by the HFC network management system to provide privileged services to the premium subscribers on HFC networks.

• Journal of Digital Convergence
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• v.11 no.3
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• pp.209-219
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• 2013

Smart phone environment have an effect on consumer life style, as well as advances in technology. In this paradigm shift on digital convergence make change to commodities, services, and distribution channels for consumers. HomePlus wholesale that is representative distribution company in Korea launched the new distribution channel model that combined off-line store with online store and mobile shopping system called 'smart mobile virtual store'. That is highly praised by abroad media and festivals. This study is an exploratory study on consumer-centric smart mobile virtual store of HomePlus. There are value and chance for developing the new digital distribution model, in this study, because the case study and evaluation of consumers is important in this momentous time.

• Journal of the Korea Society of Computer and Information
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• v.15 no.3
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• pp.55-63
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• 2010

On Handoff, existing AP search has chosen one of various APs according to signal strength. However IEEE 802.11 uses Medium Access method with CSMA/CA(Carrier Sensing Multiple Access /Collision Avoidance) that competes to obtain a channel by sharing common medium. For that reason, network performance is heavily affected by the number of nodes and network congestion aside from signal strength. Consequently, in this paper we propose the method that choose one AP which ensures more improved network performance and set up a link, reflecting AP network information in Handoff area, on Handoff in the process of AP selection. We also demonstrate through simulation that it gets maximum performance even in the wireless network which many users concurrently access to, and it has considerable effects on aspects of resources and network management by distribution of users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7B
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• pp.477-487
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• 2008

Congestion control of the TCP reduces transmission rate when it detects packet loss because packet loss origines from congestion in the wired network. In the wireless network, packet loss comes from channel errors. Wired TCP degrades performance when there are wireless losses because it does not classify type of loss. These day, there are many researches which classify type of loss between congestion loss and wireless loss for wired-wireless hybrid network. For wireless TCP, many of existing algorithms are based on the estimated bandwidth or variations of packet arrival time. In this paper, we propose a new TCP scheme to distinguish the wireless packet losses from the congestion packet losses using MIB of the IEEE 802.11 MAC. We perform excessive simulations using the NS-2 network simulator and analyze the simulation results to compare the performance of the proposed algorithm to other well-known algorithms. From simulation results, we know that proposed algorithm improves performance about 12% and 32% compared with Spike algorithm and mBiaz algorithm, respectively.

• Journal of Digital Convergence
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• v.14 no.9
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• pp.251-264
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• 2016

The purpose of this study is to compose direction about mUC as a communication channel in the company. Recently, many companies have started to adopt or try to vitalize the use of mUC. This study starts from the viewpoint of communication which is the original purpose of SNS or mUC. The purpose and function of life-world are drawn based on Habermas' theory of communicative action. Firstly, this study will check on a difference in usage over the action and articulation between SNS and mUC. Secondly, this study will examine a difference of effect of life-world between SNS and mUC. Thirdly, to check that there is difference according to the user characteristics. The result is that there are differences about action and articulation but little differences of effect to the life-world between SNS and mUC. Also, there is difference according to the user characteristics. This study could contribute to compose direction when a company adopts or vitalizes mUC.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.5
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• pp.369-378
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• 2003

This paper presents design and VLSI implementations of a reassembly processor for ATM/AAL. The assembly processor is responsible for processing ATM cells from the receive physical interface. It controls the transfer of the AAL payload to host memory and performs all necessary SAR and CPCS checks. We propose the improved structure of cell identification algorithm and smart scatter method for host memory management. The proposed cell identification algorithm quickly locates the appropriate reassembly VC table based on the received VPI./VCI channel value in the ATM header. The cell identification algorithm also allow complete freedom in assignment of VCI/VPI values. The reassembly processor uses a smart scatter method to write cell payload data to host memory. It maintains the scatter operation and controls the incoming DMA block during scatter DMA to host memory. The proposed reassembly processor can perform reassembly checks on AAL. OAM cell. For an AAL5 connection, only CPCS checks, including the CRC32, are performed. In this paper, we proposed a practical reassembly architecture. The design of reassembly processor has become feasible using 0.6${\mu}{\textrm}{m}$ CMOS gate array technology.

• Journal of the Korea Convergence Society
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• v.8 no.3
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• pp.215-223
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• 2017

The purpose of the present study is to identify the differences of customer preference in online and offline used car business. Conjoint analysis is used for examining the attributes of used car choices. As a result, the order of importance in real used car market is as follows: brand, design, price, model, mileage. Whereas the order of importance in online used car market is as follows: brand, trust, price, web design, accident. Accordingly, the author suggested that customer preferences depend on the path people are approaching and the attributes of preference vary in online and real stores. For example, trust and accident are important attributes in online market in comparison with real market. Used car market is increasing and becoming important. The authorities and practitioners need to understand used car market and establish the related policies.