• The Korean Journal of Quaternary Research
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• v.20 no.2
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• pp.11-29
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• 2006

A bedrock river is a channel in which bedrock is exposed along the channel bed or walls for at least approximately half of its length. In some case, a continuous alluvial veneer may be present, but this is completely mobilized during floods. From the point of long term landscape evolution during the Quaternary, the bedrock channel determines local base level and the lowering rate of bedrock channels controls the rate of erosion and transport processes and forms on the adjacent hillslopes. In this review, various erosional processes in bedrock river channels are classified and discussed. Especially, theoretical and numerical models on channel bed abrasion with bed load sediment particles are introduced and discussed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.251-256
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• 2011

In this paper, we analyze the distance between two systems, WiBro and WLAN, compared to standard interference probability for channel co-use in order to be used as a criteria in realization. Co-channel and adjacent channel interference probability and its effect of (WiBro) into Wireless LAN (WLAN) in TV White Spaces (TVWS) is evaluated through Spectrum Engineering Advanced Monte Carlo Analysis Tool(SEAMCAT) based on the Monte-Carlo simulation method. As a result, in the case of co-channel interference, the minimum distance between WiBro Mobile Station(MS) and WLAN User Equipment (UE) should be 210 m to allow the maximum transmitter power of WiBro UE of 25 dBm. The transmit power of WiBro BS have to be reduced to -4.96 dBm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.6 no.1
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• pp.21-26
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• 1981

The effect of wideband FDM-FM signal on binary CPSK signal in an interchannel interference environment has been investigated. A general equation of the bir error rate of binary CPSK signal with cochannel and adjacent channel interference from FDM-FM signal has been derived. The numerical results are given in graphs as the functions of carrier to noise ratio (CNR), carrier to interference ratio(CIR) and normalized carrier separation between PSK and FM signals. The results obtained can be used om desogmomg tje freqiemcy allocation, bandwidths and powers of PSK and FM signals in same radio frequency (RF) bands.

• ETRI Journal
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• v.30 no.1
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• pp.21-32
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• 2008

Cognitive radio (CR) has been proposed as an effective technology for flexible use of the radio spectrum. The interference between primary users and CR users, however, becomes a critical problem when they are using adjacent frequency channels with different transmission power levels. In this paper, a robust CR orthogonal frequency division multiplexing (OFDM) architecture, which can effectively suppress interference to nearby primary users and overcome adjacent channel interference (ACI) to the CR user, is proposed. This new approach is characterized by adaptive data repetition for subcarriers under heavy ACI, and adaptive time spreading for subcarriers near the borders of the CR user's spectrum. The data repetition scheme provides extra power gain against the ACI coming from primary users. Time spreading guarantees an acceptable interference level to nearby primary users. By computer simulation, we demonstrate that, under a CR environment, the proposed CR OFDM architecture outperforms conventional OFDM systems in terms of throughput and BER performance.

• Proceedings of the Korea Contents Association Conference
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• 2006.11a
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• pp.52-57
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• 2006

This research studies and analyzes the current trends and the frequency allocation bands for digital cordless phone(DCP) in other county. From these results, we propose 1.7GHz & 2.4GHz as a effective candidate frequency band for domestic DCP. A proposed 1.7GHz is expected to introduce DECT system of Europe. Therefore it is necessary to make an analysis of interference between 1.7GHz band and an adjacent IMT-2000 band. In this paper, we proposed the allocation of channel for 1.7GHz on the basis of the analysis of frequency interference between 1.7GHz band and an adjacent IMT-2000 band.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.179-184
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• 2011

In this paper, we analyze the sharing parameters in order to co-use of different communication systems in adjacent channels. We analyze the performance result according to various density of interfering transmitter and transmitter output in hetero systems. In order to get the relationship with between density of interfering transmitter and transmitter output, we consider the case that WiBro is an interfering transmitter an WLAN is a victim receiver. When the center frequency of WLAN is 687MHz and interferer density is 50/$km^2$, required guard band is 10MHz. Analyzed coexistence results may be widely applied into the technique developed to get the coexisting condition for wireless devices using many communication protocols in same frequency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.2
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• pp.159-164
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• 2005

When an optical pulse propagates through the atmospheric channel, the atmospheric turbulence attenuates and spreads this pulse. This attenuation and broadening of pulse are occurred by the fluctuation in the arrival time of pulse at the optical receiver. This pulse broadening induces the intersymbol interference (ISI) between the adjacent pulses. finally, the adjacent pulses are overlapped and the bit rate and the repeaterless transmission length are limited by the ISI. In digital communication system, therefore, the pulse broadening is more important factor than the attenuation. In this paper, thus, we find the ISI in the atmospheric turbulence as the function of the structure constant for the refractive index fluctuation that presents the strength of turbulence using the temporal momentum function and present it by numerical analysis.

• The Journal of the Korea Contents Association
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• v.7 no.3
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• pp.60-67
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• 2007

This research studies and analyzes the current trends and the frequency allocation bands for digital cordless phone(DCP) in other country. From these results, we propose 1.7GHz & 2.4GHz as a effective candidate frequency band for domestic DCP. A proposed 1.7GHz is expected to introduce DECT system of Europe. Therefore it is necessary to make an analysis of interference between 1.7GHz band and an adjacent IMT-2000 band. In this paper, we proposed the allocation of channel for 1.7GHz on the basis of the analysis of frequency interference between 1.7GHz band and an adjacent IMT-2000 band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.10
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• pp.1186-1189
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• 2016

A distributed uplink power control algorithm based on flocking model is proposed to improve the energy efficiency of mobiles station (MS) in cellular networks. As each bird in a flock matches its velocity with the average velocity of the adjacent birds, each MS in a cell matches its uplink rate with the average uplink rate of the co-channel MSs in adjacent cells by controlling its transmission power. Results show that the proposed algorithm effectively reduces the power consumption in the MS, while maintaining a low outage probability, which eventually improves the energy efficiency of the MS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.724-730
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• 2002

Digital communication systems are required to cause the minimum interference to adjacent channels, they must therefore employ the linear power amplifiers. In respect to linear power amplifiers, there are many linearization techniques. Feedforward power amplifier represent very wide bandwidth and high linearization capability. In the feedforward systems, overall efficiency is reduced due to the loss of delay line. In this paper, delay filter instead of transmission delay line adapted to get more high efficiency. Experimental results showed that ACLR (Adjacent Channel Leakage Ratio) has improved 17.43(dB), which is added 3.44(dB) by using the delay filter.