• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.33-36
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• 2000

In this paper, the performance of the W-CDMA system with smart antenna is investigated. The channel is assumed as wideband realistic channel mode, JTC(Joint Technique Committee), which has clustered multipaths. The beamforming-RAKE receiver structure is proposed, whose performance is analyzed on the assumption of the perfect channel estimation. In a simulation, the probability density function(pdf) of SINR(Signal to Interference and Noise Ratio) according to the number of antennas and users is presented. And based on the pdf of SINR, the BER(Bit Error Rate) is presented. According to the result of a simulation, the performance of the W-CDMA system with smart antenna over the realistic JTC channel model has been considerably improved.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.193-196
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• 2000

In this paper, the performance of DS-CDMA system with smart antenna is analyzed for different bandwidths (1.25MHz, 5MHz) and different channel environments (rural, urban). For the analysis of smart antenna system, the vector channel model having the spatio-temporal correlation is needed. Hence, the channel is modeled as a time-variant linear filter in time, and each multipath is assumed as a reflective wave from only one direction (only one cluster) in space. A simulation is carried out by dividing several multipaths within one chip into each one and searching the strongest signal. DS-CDMA system with smart antenna using wider bandwidth present better performance than that using narrow bandwidth. It is shown that the smart antenna is more effective in urban area when using 2D-RAKE receiver.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.75-78
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• 2004

In this paper, we analyze the performance of transmitter and receiver of W-CDMA system using the channel coding and space time code in downlink over ITU-R realistic channel model. We can improve the data rate and the reliability of communications by a channel code, and we can get a diversity gain by using the space time code over fading channels. We also apply the RAKE receiver to improve a performance in multi-path fading channel environment.

• The Journal of the Acoustical Society of Korea
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• v.17 no.3E
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• pp.58-66
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• 1998

In this paper, we analyze the effects of interference canceller on the performance of multitone DS/CDMA system proposed by Vandendorpe[5]. There are various kinds of interference canceller suggested by different researchers including parallel and successive cancellers and we adopt a canceller used by Yoon et al.[9] which is a kind of parallel canceller. We consider three kinds of interferences, that is, multipath interference(MPI), interchannel interference(ICI) and multiple access interference(MAI). The ICI is the interference between multitones. The equations for variances. are derived for the inteferences and thermal noise used for signal to noise ratio calculation. We also consider RAKE reception over multipath channel which is modeled as lowpass equivalent linear filter and three stage interference canceller used for performance improvement. We show the performance results for number of canceller stage, diversity order and number of users and draw some conclusions that interference canceller is effective in multitone DS/CDMA system and the performance is further improved with the higher order of diversity and larger number of PN chips.

• Journal of Korean Physical Therapy Science
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• v.24 no.3
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• pp.12-17
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• 2017

Purpose: The purpose of this study was to investigate the effects of backrest angle on lower extremity muscle strength in adult. Method: This research results are based on 10 healthy adults. 10 degree difference in pelvic angle does not effect the cross-connection of the Hamstring muscles, and created 3 types of rest with 20 degree differences each at 95, 115, and 135 degree angles. Result: significantly difference in contractibility muscle strength in accordance to the 3 rake angle. Conclusion: After putting together all these results, since both the expansibility muscle strength and contractibility muscle strength of the knee showed to be effected as the backrest angle changed during isokinetic muscle strength assessment, further research should be conducted if similar research results as this study can be acquired at various angles.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.959-962
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• 2001

Turbo codes of long block sizes have been known to show very good performance in an AWGN channel and the turbo code has been strongly recommended as error correction code for IMT-2000 in 3GPP(3rd Generation Partnership Project). Recently, turbo codes of short block sizes suitable for real time communication systems have attracted a lot of attention. Thus, in this paper we consider the turbo code of 1/3 code rate and short frame size of 192 bits in ITU-R channel model. We analyzed the performance of W-CDMA systems of 10MHz bandwidths employing RAKE receiver with not only MRC diversity but also turbo code.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.587-590
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• 2001

본 논문에서는 스마트 안테나를 적용하여 서로 다른 대역폭(1.25MHz, 5Mhz)과 서로 다른 환경(rural, urban)에서 W-CDMA 시스템의 성능을 분석하였다. 먼저 스마트 안테나 시스템의 성능을 분석하기 위해서 시·공간 상관특성을 갖는 채널이 필요하다. 이를 위해 시간 정보를 고려하기 위해 시변 선형 필터로 모델링하였고, 공간 정보를 고려하기 위하여 배열 응답 벡터를 삽입하였다. 이 때 공간적으로는 일정량의 각도 퍼짐을 갖는 부-다중경로 성분으로 구성된 한 개의 반사파가 한 방향으로부터만 수신된다고 가정하였다. 또한 한 칩 내에 들어오는 다중 경로 성분을 분리하여 가장 큰 신호 성분만을 찾아내어 원하는 사용자의 신호로 사용하는 방법으로 모의 실험을 실행하였다. 모의실험 결과, 협대역 CDMA를 사용하는 스마트 안테나 시스템보다 광대역 CDMA를 사용하는 스마트 안테나 시스템이 더 나은 성능을 보임을 확인할 수 있었다. 또한 스마트 안테나는 2D-RAKE receiver를 사용했을 때 urban area에서 보다 더 효과적임을 확인할 수 있었다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.579-582
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• 2001

The performance of a coherent rake receiver of DS-CDMA systems is significantly affected by the accuracy of channel estimation. The performance of the channel estimator can be improved by employing a channel estimation filter (CEF) whose impulse response is adjusted according to the channel condition. In this paper, we consider the design of an adaptive channel estimator for DS-CDMA systems with a pilot channel. The proposed channel estimator estimates the channel condition, which can be performed without haying exact a priori information on the operating condition. The estimated channel condition adjusts the impulse response of the CEF. Numerical results show that the use of the proposed channel estimator can provide BER performance quite robust to a wide range of channel condition.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.91-94
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• 2000

In this paper, the performance of the W-CDMA system with smart antenna is investigated. The realistic wideband channel is assumed, one of which is JTC(Joint Technique Committee) channel model. It is also assumed that multipaths are clustered. The beamforming-RAKE receiver structure of W-CDMA system is proposed, whose performance is analyzed on the assumption of perfect channel estimation. The probability density function (pdf) of SINR(Signal to Interference and Noise Ratio) for different number of antennas and users is presented, and the BER(Bit Error Rate) is presented based on that. As a result, the performance of the W-CDMA system with smart antenna in the realistic wideband channel has been considerably improved.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.79-82
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• 2000

In this paper, the performance of 05-CDMA system with smart antenna is analyzed for different bandwidths (1.25MHz, 5MHz) and different channel environments (rural, urban). For the analysis of smart antenna system, the vector channel having the spatio-temporal correlation is modeled as a time-variant linear filter in time, and each multipath is assumed as a reflective wave from only one direction (only one cluster) in space. Several multipaths within one chip are distinguished into each one and the strongest signal is selected. DS-CDMA system with smart antenna using wider bandwidth present better performance than that using narrow bandwidth. It is shown that the smart antenna is more effective in urban area when using 2D-RAKE receiver.