• Journal of IKEEE
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• v.5 no.1 s.8
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• pp.1-7
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• 2001

In this paper, we have investigated the CDMA(Code Division Multiple Access) Cellular System with non-linear equalizer in reverse link channel. In general, due to unknown characteristics of channel in the wireless communication, the distribution of the observables cannot be specified by a finite set of parameters; instead, we partitioned the m-dimensional sample space Into a finite number of disjointed regions by using quantiles and a vector quantizer based on training samples. The algorithm proposed is based on a piecewise approximation to regression function based on quantiles and conditional partition moments which are estimated by Robbins Monro Stochastic Approximation (RMSA) algorithm. The resulting equalizers and detectors are robust in the sense that they are insensitive to variations in noise distributions. The main idea is that the robust equalizers and robust partition detectors yield better performance in equiprobably partitioned subspace of observations than the conventional equalizer in unpartitioned observation space under any condition. And also, we apply this idea to the CDMA system and analyze the BER performance.

• Progress in Medical Physics
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• v.23 no.3
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• pp.162-168
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• 2012

In proton therapy, in vivo dose verification is one of the most important parts to fully utilize characteristics of proton dose distribution concentrating high dose with steep gradient and guarantee the patient safety. Currently, in order to image the proton dose distribution, a prompt gamma distribution detection system, which consists of an array of multiple CsI(Tl) scintillation detectors in the vertical direction, a collimator, and a multi-channel DAQ system is under development. In the present study, the optimal design of prompt gamma distribution detection system was studied by Monte Carlo simulations using the MCNPX code. For effective measurement of high-energy prompt gammas with enough imaging resolution, the dimensions of the CsI(Tl) scintillator was determined to be $6{\times}6{\times}50mm^3$. In order to maximize the detection efficiency for prompt gammas while minimizing the contribution of background gammas generated by neutron captures, the hole size and the length of the collimator were optimized as $6{\times}6mm^2$ and 150 mm, respectively. Finally, the performance of the detection system optimized in the present study was predicted by Monte Carlo simulations for a 150 MeV proton beam. Our result shows that the detection system in the optimal dimensions can effectively measure the 2D prompt gamma distribution and determine the beam range within 1 mm errors for 150 MeV proton beam.

• The Journal of Fisheries Business Administration
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• v.23 no.2
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• pp.101-128
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• 1992

How to distribute fisheries catches from producer to consumer is very important for everybody joined fisheries marketing channels (FMC), because most people are influenced their revenue and expenditure through marketing channels. Many institutions in Korea after 1960's have tried to develop the rationalization of FMC, but they have not gotten the satisfactory results in general in spite of a lot fruits. Comparing with general manufacturing industry, the fisheries industry has some specializations in the marketing channels. It makes them unique structure included wholesale market system similiar to fresh (perishable) food market with expertised technology. Wholesale market collects, distributes the fisheries catches and evaluates in by auction or bidding without consideration of producer's opinion. It is very necessary institution to make a decision to equatible price for fresh food and to play an important role for marketing effectiveness with minimum total transation and with massed reserve among institutions. But it has two weak points to increase the marketing cost and to make products bad fresh (perishable). Therefore, both Producer and consumer want to find the direct channels not to pass through wholesale market and to get more profit. I wanted to explain what problems of traditional FMC are and why the direct channel is necessary as follows in this paper. Chapter II : The types and specialization of FMC Chapter III : The structure and problem of fisheries wholesale market channel Chapter IV Marketing cost of FMC and direct channel I suggested when the direct channel in FMC is designed, new planner must carry out marketing functions which are performanced by wholesaler, middle man and the joined members of auction at wholesale market. In view of consumption area, these functions are : (1) the finding of production partner to make a business ; (2) communication of information ; (3) collecting ; (4) distribution ; (5) selecting and grading ; (6) evaluating ; (7) financing and payment ; (8) organization, in view of consumption area. The government must support also the group or individual of new direct channels to succeed it with (1) furnishing of market information (2) supplying of land and facility (3) financing (4) feed-back of dierct channels totally (5) making an opportunity of communication between producer and consumer. I want to emphasize again wholesale market is necessary and important institution for equatible price of fresh food in spite of the its weak points. At the same time. the direct channels are necessary to reduce the marketing cost and to keep better fresh food.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.7
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• pp.648-656
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• 2009

We perform an analysis of the characteristics of the time-reversal pulse in Rayleigh or Ricean fading channel environments. We verify it by using Monte Carlo simulation. In a time-reversal system, each antenna in the time-reversal array receives signals from the transmitter and reverse the received signal in the time axis and then resend it to the original transmitter. We assume that the channel characteristics varies very slowly and the spatial separation between the antennas is not large. Hence the signals received by each antenna are correlated. In this paper, the effect of the correlation on the time-reversed pulse is examined, which includes the spatial properties of the time-reversal pulse such as the focus size, and spatial power distribution.

• Journal of Distribution Science
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• v.7 no.4
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• pp.47-56
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• 2009

The purpose of this study is to present an alternative improving the efficient and reasonable of the physical distribution system management is influenced by many factors. Therefore, the study depends on the documentary method and survey method to achieve the purpose of this study. The major components of a physical distribution system are refers to as elements, include warehouse·storage system, transportation system, inventory system, physical distribution information system. The factors used in this study are ① factor of product(quality·A/S·added value of product·adaption of product·technical competitive power to other enterprises), ② factor of market(market channel·kinds of customer·physical distribution share), ③ factor of warehouse·storage(warehouse design·size·direction·storage ability·warehouse quality), ④ factor of transportation(promptness·reliability·responsibility·kinds of transportation·cooperation united transportation system·national transportation network), ⑤ factor of packaging (packaging design·material·educating program·pollution degree measure program), ⑥ factor of inventory(ordinary inventory criterion·consistence for inventories record), ⑦ factor of unloaded(unloaded machine·having machine ratio), ⑧ factor of information system (physical distribution quantity analysis·usable computer part), ⑨ factor of physical distribution cost(sales ratio to product) ⑩ factor of physical distribution system(physical distribution center etc). The implication of this study can be summarized as follows: ① In firms that have not adopted a systems integrative approach, physical distribution is a fragmented and often uncoordinated set of activities spread throughout various functions with function having its own set of priorities and measurements. ② The physical distribution is recognized as more an important strategic factor than a simple cost reduction factor, ③ It can be used a strategic competition tool to enterprise.

• The Journal of the Acoustical Society of Korea
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• v.32 no.4
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• pp.346-353
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• 2013

This paper deals with the implementation of a high-quality audio system for karaoke. For improving the key/tempo changes performance, we separated the audio into many musical instrument channels. By separating musical instrument channels, high-quality key/tempo changes can be achieved and we confirmed this using the cross-correlation distribution and the MOS evaluation. The improved audio system was implemented using the TMS320C6747 DSP with fixed/floating-point operations. The implemented audio system can perform the multi-channel WMA decoding, the MP3 encoding/decoding, the wav playing, the EQ, and the key/tempo changes in real time. The WMA channels used for processing the separated instrument channels. The audio system includs the MP3 encoding/decoding function for playing and recording and the wav channel for the effect sound.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1638-1654
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• 2018

The heterogeneous network (HetNet) has been one of the key technologies in Long Term Evolution-Advanced (LTE-A) with growing capacity and coverage demands. However, the introduction of femtocells has brought serious co-layer interference and cross-layer interference, which has been a major factor affecting system throughput. It is generally acknowledged that the resource allocation has significant impact on suppressing interference and improving the system performance. In this paper, we propose a hybrid-clustering algorithm based on the $Mat{\acute{e}}rn$ hard-core process (MHP) to restrain two kinds of co-channel interference in the HetNet. As the impracticality of the hexagonal grid model and the homogeneous Poisson point process model whose points distribute completely randomly to establish the system model. The HetNet model based on the MHP is adopted to satisfy the negative correlation distribution of base stations in this paper. Base on the system model, the spectrum sharing problem with restricted spectrum resources is further analyzed. On the basis of location information and the interference relation of base stations, a hybrid clustering method, which takes into accounts the fairness of two types of base stations is firstly proposed. Then, auction mechanism is discussed to achieve the spectrum sharing inside each cluster, avoiding the spectrum resource waste. Through combining the clustering theory and auction mechanism, the proposed novel algorithm can be applied to restrain the cross-layer interference and co-layer interference of HetNet, which has a high density of base stations. Simulation results show that spectral efficiency and system throughput increase to a certain degree.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2007.05a
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• pp.101-110
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• 2007

Current strategic trends in service distribution and software development in response to Web as a platform represent a paradoxical concurrent pursuit of 'economy of scale' and 'service'. From the software perspective, the major novel elements of the Web 2.0 era are Web as a platform and the emergence of long-tail service enabling web sites to function as an independent distribution channel. The current study analyzed the platform strategy for establishing a community of interactive developer and customers taking the issue of economy of scale into consideration. Software industry should face the new reality and utilize the open source community for cost minimization and securing customer base. Furthermore, Lego-style software development should be adopted for maintaining cost-competitiveness in customized software development.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.10
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• pp.522-531
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• 2001

A large dispersion value in optical fiber cable should be maintained to suppress the nonlinear effect induced distortion for the narrow channel spaced DWDM system while small value of dispersion is needed for high bit rate transmission. To meet these two requirement simultaneously, dispersion distribution control method during the cabling process was exploited. And dispersion distribution cable was fabricated by the way of designing alternation sections in single cable piece with standard single mode fiber(SSMF) and newly developed negative dispersion fiber(NDF). It is shown that the discretely dispersion varying cable along the axis keep the same average dispersion value of an entire cable length as that of nonzero dispersion shifted fiber(NZDSF) with 3.6 ps/km/nm while the local dispersion is around 17 ps/km/nm of absolute value. Moreover, the developed cable had good optical and mechanical properties and the feasibility of this cable for practical use was confirmed.

• Journal of Communications and Networks
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• v.6 no.1
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• pp.1-8
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• 2004

In this paper, we investigate the properties and performance of space-time bit-interleaved coded modulation (STBICM) systems in fast Rayleigh fading channels. We first show that ST-BICM with QPSK signaling in fast fading channels possesses the uniform distance property, which makes performance analysis tractable. We also derive the probability distribution of the squared Euclidean distance between space-time symbols assuming uniform bit-interleaving. Based on the distribution, we show that the diversity order for each codeword pair becomes maximized as the frame length becomes sufficiently long. This maximum diversity order property implies that the bit-interleaver transforms an ST-BICM system over transmit diversity channels into an equivalent coded BPSK system over independent fading channels. We analyze the performance of ST-BICM in fast fading channels by deriving an FER upper bound. The derived bound turns out very accurate, requiring only the distance spectrum of the binary channel codes of ST-BICM. Numerical results demonstrate that the bound is tight enough to render an accurate estimate of performance of ST-BICM systems.