• The Journal of Korean Institute of Communications and Information Sciences
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• v.9 no.4
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• pp.157-162
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• 1984

The data transmission in radio channel is mainly influenced by interfere and random noise. The increasing man-made impulsive noise environment has the necessity to consider impulsive noise than conventional white gaussian noise in digital communications. In this paper, we have investigated the error rate performance of hybrid modulation system. AFSK, which is composed of ASK and FSK in the environment of electromaganetic interference (EMI), especially impulsive noise.

• Journal of the Korean Society for Railway
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• v.11 no.3
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• pp.248-256
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• 2008

The study aims at verifying no generation of electrical power induced noise voltage on telecommunications lineside cable by analyzing the practical findings of noise voltage produced at the telecommunication lines in the vicinity of electrified high-speed railways like KTX, while proposing to make the current standard measurement circuit along with its measuring conditions revised in compliance with international ITU-T recommendations by identifiably finding out the present problems in balance level measuring instruments as well as their errors in the measurement method now applicable by local telecommunications companies and the Radio Research Laboratory.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.6 s.121
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• pp.648-655
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• 2007

In this paper, we introduce a dual coil antenna which is useful for reducing the effects of radio frequency noise in an RFID system. A dual coil antenna is composed of two identical coils that are connected in series. The noise voltages in the two coils almost disappear when they are added because the magnitudes are equal and the polarities are opposite. The noise in an RFID reader with a dual coil antenna was 15 dB lower than that with a single coil antenna.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1984.10a
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• pp.37-42
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• 1984

In this paper, the error rate equation of MSK system through the Nakagami's m-distribyted fading channel has been derived in the interference and inpulsive noise invironments. The evaluated performances are shown and discussed in terms of carrier-to-noise power ratio, carrier-to-interferer power ratio, fading figure, and impulsive indexes.

• Bulletin of the Korean Chemical Society
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• v.32 no.10
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• pp.3821-3823
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• 2011

• Publications of The Korean Astronomical Society
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• v.12 no.1
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• pp.185-196
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• 1997

We present a code which identifies individual clouds in crowded region using IMFORT interface within Image Reduction and Analysis Facility (IRAF). We define a cloud as an object composed of all pixels in longitude, latitude, and velocity that are simply connected and that lie above some threshold temperature. The code searches the whole pixels of the data cube in efficient way to isolate individual clouds. Along with identification of clouds it is designed to estimate their mean values of longitudes, latitudes, and velocities. In addition, a function of generating individual images (or cube data) of identified clouds is added up. We also present identified individual clouds using a $^{12}CO$ survey data cube of Galactic Anticenter Region (Lee et al. 1997) as a test example. We used a threshold temperature of $5\sigma$ rms noise level of the data With a higher threshold temperature, we isolated subclouds of a huge cloud identified originally. As the most important parameter to identify clouds is the threshold value, its effect to the size and velocity dispersion is discussed rigorously.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.16 no.4
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• pp.301-308
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• 1991

In this paper, we have proposed a demodulation circuit of radio data receiver system and calculated the error probability of the digital transmitted signal corrupted under noise environment. And we have evaluated the error performance of the proposed system. The designed demodulation circuits have been implemented by using the general random logic and PLL circuits, which can be possible for the integrated circuit design of the radio data receiver system. In addition calculation of bit error rate in recovered digital signal has been accomplished ans we have confirmed that the proposed system hsa the equivalent performance with already existing ones.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.482-483
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• 2011

본 논문에서는 스마트TV향 VoIP(Voice over Internet Protocol) 컨퍼런스 기능을 위한 잡음제거 알고리즘의 성능비교 하였다. 기존에 연구 되어져 있는 Improved Minima Controlled Recursive Averaging(IMCRA)방식과 Gaussian분포 기반의 잡음제거 알고리즘, IMCRA방식과 Gamma분포 기반의 잡음제거 알고리즘, IMCRA방식과 Mel-filter를 적용한 잡음제거 알고리즘, R&L 알고리즘들의 방식을 비교하였으며, 성능 비교를 위해 각 알고리즘을 통해 나온 다양한 잡음 환경에서의 잡음이 제거된 신호의 PESQ와 연산속도를 비교한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.458-466
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• 2008

Spectrum sensing is the key challenge in implementing cognitive radio system, which enables unlicensed users to identify "white holes" in the spectrum allocated to primary users and utilize them efficiently. Recent studies have proposed three major sensing methods for WRAN systems, including matched filter, energy and feature detector. However, there are some drawbacks along with them. In this paper, we propose an enhanced energy detector that extends the ability of conventional one, which can differentiate the primary users from each other as well as the noise with different maximum-to-mean power ratio. Furthermore, a novel structure of cognitive radio detector employing the proposed algorithm is also analyzed to implement spectrum sensing. The simulation result shows that our proposed scheme performs well in the individual sensing environment and can satisfy the requirement with high detection probability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1006-1022
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• 2010

In this paper, a cross-layer resource allocation mechanism is proposed for wireless multimedia service. In particular, a game theory based on quality of service (QoS) for multimedia users is introduced to deal with the fairness of network resource allocation in wireless networks. Moreover, the channel states of wireless users are additionally regarded under the cross-layer design in WiMAX environment. In details, the bargaining solution is adopted to discover the efficient and fair resource allocation strategy for multimedia service in considering QoS in the peak signal-to-noise ratio (PSNR) and the channel states in the carrier-to-interface ratio (CINR). The proposed mechanism is illustrated and evaluated by simulation results of transmitting video sequences in WiMAX environment.