• Journal of information and communication convergence engineering
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• v.16 no.1
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• pp.38-42
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• 2018

In this paper, we consider measurement allocation problem in a spatially correlated sensor field. Our goal is to determine the probability of each sensor's being measured based on its contribution to the estimation reliability; it is desirable that a sensor improving the estimation reliability is measured more frequently. We consider a spatial correlation model of a sensor field reflecting transmission power limit, noise in measurement and transmission channel, and channel attenuation. Then the estimation reliability is defined distortion error between event source and its estimation at sink. Motivated by the correlation nature, we model the measurement allocation problem into a cooperative game, and then quantify each sensor's contribution using Shapley value. Against the intractability in the computation of exact Shapley value, we deploy a randomized method that enables to compute the approximate Shapley value within a reasonable time. Besides, we envisage a measurement scheduling achieving the balance between network lifetime and estimation reliability.

• Journal of Magnetics
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• v.4 no.2
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• pp.65-68
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• 1999

The M-type barium ferrite ($BaFe_{12}O_{19}$) is well known magnetic material to be used as a permanent magnet due to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ to its strong uniaxial anisotropy. The substitution of nonmagnetic $Ti^{+4}$ and magnetically weak $Co+^2ion for Fe^{+3}$ sublattices reduces the uniaxial anisotropy and those compounds open a new application field of noise suppressor at high frequencies. In this study, the magnetic and microwave absorbing properties are investigated in Ti-and Co-substituted barium ferrites ($BaFe_{12-2X} Ti_XCo_XO_{19}$). The saturated magnetization decreases linearly with the substitution of Ti and Co. The rapid drop in coercive force is observed with Ti and Co substitution upto x=1.2. The magnetic permeability spectrum shows the natural magnetic resonance in the specimens with small coercive force and large attenuation of microwave is predicted in those specimens at high frequencies (above 4 GHz).

• Journal of Integrative Natural Science
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• v.13 no.1
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• pp.1-7
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• 2020

This paper proposes a novel fractional frequency reuse(FFR) based on dynamic user distribution. In the FFR, a macro cell is divided into two regions, i.e., the inner region(IR) and outer region(OR). The criterion for dividing the IR and OR is the distance ratio of the radius. However, these distance-based criteria are uncertain in measuring user performance. This is because there are various attenuation phenomena such as shadowing and wall penetration as well as path loss. Therefore, we propose a novel FFR based on dynamic user classification with signal to interference plus noise ratio(SINR) of macro users and classify the FFR into two regions newly. Simulation results show that the proposed scheme has better performance than the conventional FFR in terms of SINR and throughput of macro cell users.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.49 no.9
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• pp.546-553
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• 2000

W e have developed a power line simulator which is one of the basic tools for the research of the power line communication and its control system. In the developed simulators, we have considered the transfer function of the power line, noises and signal attenuation characteristics. Simulator was made using the matlab tool program. We made the power line modem using the FSK chip(ST7537) and experimentalized to show the efficiency grade of simulator. We have expected that the developed simulators are very useful in the area for the power line communication research and the control system design.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3B
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• pp.446-455
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• 2000

In this paper, we analyzed the reach performance of the FLC-C VDSL system using 4-CAP modulation scheme. We measured the attenuation of VDSL lines and their noise characteristics, and calculated the channel capacity. And then, we evaluated the VDSL coverage fro each type of cables; CPEV 0.5mm, CPEV 0.65mm, UTP3 0.5mm, UTP5 0.5mm, FS 0.4mm, FS 0.5mm. In case that FLC-C VDSL modern transmits 25.92 Mbps data over a UTP5 0.5mm cable, the VDSL reach appears to be about 570mm.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.102-104
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• 2005

This paper describes the model of the distribution grid for the broadband power line communication based on lumped-element circuits. In addition, this paper discusses various configurations of the MV distribution network in PLC. The distribution grid is not designed for communication so that it involves unfriendly conditions for PLC. The characterization of the MV distribution grid for PLC should be determined such as noise, attenuation, and mismatched impedance. For theses reasons, the PLC networks is described in using the scattering parameters. Finally, the n-port network is explained.

• Journal of Industrial Technology
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• v.19
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• pp.81-89
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• 1999

We have developed a power line simulator which is one of the basic tools for the research of the power line communication and its control system. In the developed simulators, we have considered the transfer function of the power line, noises and signal attenuation characteristics. Simulator was made using the matlab tool program. We made the power line modern using the FSK chip(ST7537) and experimentalized to show the efficiency grade of simulator. We have expected that the developed simulators are very useful in the area for the power line communication research and the control system design.

• The Journal of the Acoustical Society of Korea
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• v.17 no.3
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• pp.78-89
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• 1998

도심에서 발생하는 건설소음은 건설현장 주변의 주민들에게 불쾌감을 유발하고 있 으며 점차 주거환경을 위협하는 환경 오염원으로 등장하고 있다. 이러한 건설소음은 일반적 으로 건설기계소음과 건설공사소음으로 분류될 수 있는데, 전자의 경우 최근에 정부차원에 서 그 심각성을 인정하여 정책적으로 기초적인 연구가 수행되고 있지만 후자의 경우에는 기 초적인 자료 및 연구가 거의 전무한 상태이다. 따라서 국내에서는 이러한 건설소음을 저감 시키기 위한 실질적인 방법들이 강력히 요구되고 있으나, 기존의 연구부족과 자료의 결핍 등으로 인해 많은 어려움을 겪고 있는 실정이다. 이러한 관점에서 본 연구에서는 건설현장 에서 발생하는 건설공사소음의 전달 및 감쇠특성을 파악하고자 하였으며 향후 건설소음의 기준 설정시 기초적인 자료를 제시하고자 한다.

• Journal of Biomedical Engineering Research
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• v.17 no.2
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• pp.179-188
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• 1996

A clinically oriented 32-channel electroencephalogram (EEG) and evoked potential (EP) mapping system has been developed EEG and EP signals acquired from 32-channel electrodes attached on the heroid surface are amplified by a pre-amplifier which is separated from main amplifier and is located near the patient to reduce signal attenuation and noise contamination between electrodes and the amplifier. The amplified signals are further amplified by a main amplifier where various filtering and gain contr61 are achieved An automatic artifact rejection scheme is employed using neural network-based EEG and artifact classifier, by which examination time is substantially reduce4 The continuously measured EEG sigrlals are used for spectral mapping, and auditory and visual evoked potentials measured in synchronous to the auditory and visual stimuli are used for temporal evoked potential mapping. A user-friendly graphical interface based on the Microsoft Window 3.1 is developed for the operation of the system. Statistical databases for comparisons of group and individual are included to support a statistically-based diagnosis.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.06a
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• pp.118-123
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• 2007

A robust objective function in the frequency domain is applied to the acoustic full waveform inversion. The proposed objective function is defined as $l_1$-norm of residual wavefields in the frequency domain. Generally, the full waveform inversion is extremely sensitive to a number of factors such as parameterization, initial model, noise and so on. The numerical tests were performed for checking the sensitivity to attenuation and several noises. For the comparison with other objective functions, the conventional least-squares method and the logarithmic method were tested under the same condition. The synthetic data examples show that the proposed algorithm is more robust than the well-known methods.