• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.2
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• pp.289-295
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• 2000

Traffic analysis during past years used the Poisson distribution or Markov model, assuming an exponential distribution of packet queue arrival. Recent studies, however, have shown aperiodic and burst characteristics of network traffics. Such characteristics of data traffic enable the scalability of network, QoS, optimized design, when we analyze new traffic model having a self-similar characteristic. This paper analyzes the self-similar characteristics of a small-scale mixed traffic in a network simulation, the real WAN delay time, TCP packet size, and the total network usage.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.4
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• pp.578-587
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• 2009

In this paper, the characteristics of incompressible flow in a tube type marine fuel oil filter have been investigated. Fluent program has been used to obtain the solutions for the problems of three-dimensional, turbulent fuel oil flow in a filtering system. The inlet flow field is assumed to be uniform. The velocity and pressure distributions were obtained using Darcy's law. The increase of inlet velocity for cleaning fuel oil may cause some problems like vibration of the filter element. It was also required to consider the distribution of cleaning velocity because the worst distribution of cleaning velocity may cause the local insufficient cleaning effect and furthermore the effective filtration area can be reduced. The simulated results show that the computer code can be successfully applied for simulation of the complex base oil flow through the porous media. This paper could be applied to the design of auto-backwashing filtering system as design factor.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.223-231
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• 2015

As smartphones support a variety of applications and their memory demand keeps increasing, the design of an efficient memory management policy is becoming increasingly important. Meanwhile, as nonvolatile memory (NVM) technologies such as PCM and STT-MRAM have emerged as new memory media of smartphones, characterizing memory references for NVM-based smartphone memory systems is needed. For the deep understanding of memory access features in smartphones, this paper performs comprehensive analysis of memory references for various smartphone applications. We first analyze the temporal locality and frequency of memory reference behaviors to quantify the effects of the two properties with respect to the re-reference likelihood of pages. We also analyze the skewed popularity of memory references and model it as a Zipf-like distribution. We expect that the result of this study will be a good guidance to design an efficient memory management policy for future smartphones.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.238-241
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• 2009

In order to design a good quantizer for the underlying distribution using a training sequence (TS), the traditional approach is seeking for the empirical minimum based on the empirical risk minimization principle. As the size of TS increases, we may obtain a good quantizer for the true distribution. However, if we have a relatively small TS, searching the empirical minimum for the TS causes the overfitting problem, which even worsens the performance of the trained codebook. In this paper, the performance of codebooks trained by small TSs is studied, and it is shown that a piecewise uniform codebook can be better than an empirically minimized codebook is.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.525-528
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• 2009

Recently, image classification has been an important task in various fields. Generally, the performance of image classification is not good without the adjustment of image features. Therefore, it is desired that the way of automatic feature extraction. In this paper, we propose an image classification method which adjusts image features automatically. We assume that texture features are useful in image classification tasks because natural images are composed of several types of texture. Thus, the classification accuracy rate is improved by using distribution of texture features. We obtain texture features by calculating image features from a current considering pixel and its neighborhood pixels. And we calculate image features from distribution of textures feature. Those image features are adjusted to image classification tasks using Genetic Algorithm. We apply proposed method to classifying images into "head" or "non-head" and "male" or "female".

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.11a
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• pp.259-262
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• 2012

In this paper, we propose a new fast algorithm for effective scene change detection. The proposed algorithm exploits Otsu threshold matching technique, which was proposed earlier. In this method, the current and the reference frames are divided into square blocks of particular size. After doing so, the pixel histogram of each block is generated. According to Otsu method, every histogram distribution is assumed to be bimodal, i.e. pixel distribution can be divided into two groups, based on within-group variance value. The pixel value that minimizes the within-group variance is said to be Otsu threshold. After Otsu threshold is found, the same procedure is performed at the reference frame. If the difference between Otsu threshold of a block in the current frame and co-located block in the reference frame is larger than predefined threshold, then a scene change between those two blocks is detected.

• Journal of Information Processing Systems
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• v.9 no.3
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• pp.489-498
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• 2013

In this paper, we propose a common simulation model that can be reused for different performance evaluations of networked virtual environments. To this end, we analyzed the common features of NVEs, in which multiple regions compose a shared space, and where a user has his/her own interest area. Communication architecture can be client-server or peer-server models. In usual simulations, users move around the world while the number of users varies with the system. Our model provides various simulation parameters to customize the region configuration and user movement pattern. Furthermore, our model introduces a way to mimic a lot of users in a minimal experiment environment. The proposed model is integrated with our network framework, which supports various scalability approaches. We specifically applied our model to the interest management and load distribution schemes to evaluate communication overhead. With the proposed simulation model, a new simulation can be easily designed in a large-scale environment.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.11
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• pp.272-275
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• 1997

Noninvasive multifrequency microwave radiometry using coaxial waveguide antenna has been investigated for a homogeneous and our layer human body model. We derived finite-difference time-domain(FDTD) algorithm and equation of MUR and generalized perfectly matched layer(GPML) absorbing boundary conditions(ABCs) in cylindrical coordination. The coupling between coaxial waveguide antenna and a biological object was analyzed by use of the FDTD method using MUR and GPML ABCs to obtain the absorbed power patterns in the media. The specific absorption rates(SAR) distribution which was corresponding to the temperature distribution was calculated in each region by use of the steady-state response in FDTD method. The SAR patterns of FDTD method using MUR ABCs was compared with those of FDTD method using GPML ABCs.

• Journal of Energy Engineering
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• v.1 no.1
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• pp.97-101
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• 1992

A mathematical model has been developed for an analytical calculation of distribution coefficient (K$_1$) in the presence of a chelating agent, The newley formulated K$\_$D/ is given as a function of the mole fraction of a free metal ion in the solution, ${\beta}$, and will serve as an alternative for the tedious individual measurements of K$\_$D/. This formulation will be used to analyze the effects of the presence of chelating agents on the adsorption capacity of geologic media such as clay minerals and soils. The present method may be a significant progess for the evaluation of the transport phenomena and separation processes of metal ions (or radionuclides) in the presence of chelating agents.

• The Korean Journal of Ecology
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• v.23 no.4
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• pp.331-337
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• 2000

Fourteen different taxa of dictyostelid cellular slime molds were recovered from the alpine and subalpine zone in Mt. Paektu. In subalpine zone, six species were recovered : Dictyostelium minutum, D. brefeldianum, D. crassicaule, D. capitatum, Polysphondylium solitarium and P. pallidum. One of these species which were isolated from the soils of Larix olgensis community exhibited several distinctive features which differed from the published species. This species was designated as a new species, Polysphondylium solitarium Kang et Chang, sp. nov. When cultivated at 22~24$^{\circ}C$ on low-nutrient agar media with Escherichia coli, Polysphondylium solitarium is distinguishable from other species by the following combination of features: (ⅰ) the sorocarps with vinaceous pigmentation; (ⅱ) pseudoplasmodia radial. usually centralized and rarely subdivided; (ⅲ) the various number of whorls; (ⅳ) the spores with unconsolidated and nonconspicuous polar granules. Also, we confirmed this new species by analyzing ribosomal DNA (ITS1, ITS2 and 5.8s DNA) sequences of P. solitarium and P. violaceum.