• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.12C
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• pp.1207-1214
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• 2002

A scheduling scheme for high speed networks requires a low time complexity to schedule packets in a packet transmission time. High speed networks support a number of connections, different rates for each connection and variable packet length. Conventional round robin algorithms have a time complexity of O(1), but their short time fairness, latency and burstiness depend on the quantum of a connection due to serving several packets for a backlogged connection once a round. To improve these properties, we propose in this paper an efficient packet scheduling scheme which is based on the credits of a connection and has a time complexity of O(1). We also analyzed its performance in terms of short time fairness, latency and burstiness. The analysis results show that the proposed scheme can improve the performance compared with traditional round robin schemes. The proposed scheme can be easily utilized in high speed packet networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2A
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• pp.209-215
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• 2010

This paper describes a design of variable-length FFT/IFFT processor (VL_FCore) for OFDM-based multi-standard communication systems. The VL_FCore adopts in-place single-memory architecture, and uses a hybrid structure of radix-4 and radix-2 DIF algorithms to accommodate various FFT lengths in the range of $N=64{\times}2^k\;(0{\leq}k{\leq}7)$. To achieve both memory size reduction and the improved SQNR, a two-step conditional scaling technique is devised, which conditionally scales the intermediate results of each computational stage. The performance analysis results show that the average SQNR's of 64~8,192-point FFT's are over 60-dB. The VL_FCore synthesized with a $0.35-{\mu}m$ CMOS cell library has 23,000 gates and 32 Kbytes memory, and it can operate with 75-MHz@3.3-V clock. The 64-point and 8,192-point FFT's can be computed in $2.25-{\mu}s$ and $762.7-{\mu}s$, respectively, thus it satisfies the specifications of various OFDM-based systems.

• Journal of Digital Convergence
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• v.14 no.1
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• pp.171-179
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• 2016

The energy consumption problem in wireless sensor networks is investigated. The problem is to expend as little energy as possible receiving and transmitting data, because of constrained battery. In this paper, in order to extend the lifetime of the network, we proposed a location-based clustering algorithm for wireless sensor network with skewed-topology. The proposed algorithm is to deploy multiple child nodes at the sink to avoid bottleneck near the sink and to save energy. Proposed algorithm can reduce control traffic overhead by creating a dynamic cluster. We have evaluated the performance of our clustering algorithm through an analysis and a simulation. We compare our algorithm's performance to the best known centralized algorithm, and demonstrate that it achieves a good performance in terms of the life time.

• Journal of the Korean Data and Information Science Society
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• v.22 no.4
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• pp.671-678
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• 2011

Data mining searches for interesting relationships among items in a given database. The methods of data mining are decision tree, association rules, clustering, neural network and so on. The decision tree approach is most useful in classification problems and to divide the search space into rectangular regions. Decision tree algorithms are used extensively for data mining in many domains such as retail target marketing, customer classification, etc. When create decision tree model, complicated model by standard of model creation and number of input variable is produced. Specially, there is difficulty in model creation and analysis in case of there are a lot of numbers of input variable. In this study, we study on decision tree using intervening variable. We apply to actuality data to suggest method that remove unnecessary input variable for created model and search the efficiency.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.795-801
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• 2013

As the life which existed only offline has changed into a life part of which is led online, it is an important problem to identify whether an online user is legitimate one or not. Biometric authentication technology was developed to identify the user more correctly either online or in offline daily life. Biometric authentication is a technology where a person is identified by his or her unique characteristics, and is highlighted as a next-generation authentication technology replacing password. There are various kinds of traits unique to each individual, and biometric authentication technologies drawing on such traits use various devices and algorithms. Firstly, this paper classified such various biometric authentication technologies, and analyzed the effects of them when they are applied on smartphone, smartwatch and M2M of the different devices platforms. Secondly, it suggested the effectiveness-based AIB(Authentication for Integrated Biometrics) authentication technique, a comprehensive authentication technique, which can be used in different devices platforms. We have successfully included the establishment scheme of the effectiveness authentication using biometrics.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.5
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• pp.77-87
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• 2000

In this paper, we propose a Over-The-Cell channel routing algorithm for the advanced three-layer process. The proposed algorithm makes the channel routing problem to simplified one and makes use of simulated annealing technique to achieve the global optimal solution. And, a new method to remove the cyclic vertical constraints which are known to be the hardest element in the channel routing problem is proposed, and a way to detect the local minimal solution and escape from it successfully is presented. Futhermore, genetic algorithm based channel router is implemented and comparison is performed with the simulated annealing based one. All algorithms are written in C++ and GUI is made using Motif under Linux environment.

• Journal of the Korea Convergence Society
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• v.11 no.3
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• pp.19-26
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• 2020

In this paper, we propose a method to analyze the loss region of the dictionary-based super resolution result learned for image quality improvement and to map the learning data according to the analyzed loss region. In the conventional learned dictionary-based method, a result different from the feature configuration of the input image may be generated according to the learning image, and an unintended artifact may occur. The proposed method estimate loss information of low resolution images by analyzing the reconstructed contents to reduce inconsistent feature composition and unintended artifacts in the example-based super resolution process. By mapping the training data according to the final interpolation feature map, which improves the noise and pixel imbalance of the estimated loss information using a Gaussian-based kernel, it generates super resolution with improved noise, artifacts, and staircase compared to the existing super resolution. For the evaluation, the results of the existing super resolution generation algorithms and the proposed method are compared with the high-definition image, which is 4% better in the PSNR (Peak Signal to Noise Ratio) and 3% in the SSIM (Structural SIMilarity Index).

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2140-2146
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• 2014

Ocean buoys are operated for safe navigation and collecting ocean data. Recently, to reducing marine buoy's damage by ocean weather's bad condition and collision with vessels has been conducted in several field research. This paper's experiment is buoy condition monitoring about predefined data form by users. As a result using Wireless remote control board applying a radio signal processing algorithms, it can observe buoy's state at an interval of three minutes on the land. Acquired data type is changeable according to ocean weather condition or buoy's purpose of using in advance. Also, this paper conducted an experiment such as data-transmission's stability and wireless communication's availability. As results of the analysis of the transmitted data, the solar, wind and wave power indicates the maximum amount of power, 50 W, 20 W and 40 W respectively. The communication system proven through this research can apply to buoy or other ocean facility.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.4B
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• pp.351-360
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• 2003

All-optical network provede unlimited for bandwidth, the very low bit error rate, and the transparency to IP. Optical networks promise to be the next generation networks that can meet the higher bandwidth demands. However, the number of wavelengths is often not large enough to help a large amount of nodes. The blocking by wavelength contention can be reduced by wavelength conversion, which can't perfectly resolve all situations. Because of that, a lot of groups have proposed unique wavelength assingment algorithms and protocols. Most schemes don't support the priority concepts. This paper describes the unique priority scheme based on the throughput. In this paper, we apply our priority scheme to SWAP(Simple Wavelength Assignment Protocol) and show the performance of the proposed priority scheme. Our proposed priority scheme can be a better solution to solve an important problem about the blocking by wavelength contention into WDM optical networks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1586-1592
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• 1999

In DWMT, CMFB is employed in the synthesis/analysis part. The CMFB uses filters of greater length than the DFT, resulting in reduced interference between the carriers. In addition, the CMFB system is computationally efficient and fast algorithms are available for their implementation. Traditional designs for the prototype filters of CMFB usually involve nonlinear optimizations. Thus the required design time is considerably large even for small filter orders. In this paper, a prototype filter design method for CMFB is presented using optimal window method. The design process is reduced to the optimization of a single parameter and consequently the required design time is much less than those of the existing methods. It is shown that the stopband performance of the proposed method is better than that of the Kaiser window method.