• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2649-2656
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• 2010

MC-DS-CDMA is technique where a single data symbol is transmitted at multiple subcarriers which are orthogonal to each other. With this technique, frequency diversity can be achieved. The performance of uplink MC-DS-CDMA systems with the application of MRRC antenna diversity over time variant channels is analyzed. Time variant channels lead to interchannel interference which increases the bit error rate in the receiver. The BER performance of this system over multipath fading environment is evaluated, considering the channel estimation error, carrier frequency offset, and the nonlinear high power amplifier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1570-1578
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• 2000

A quadrature pair of filter banks that are composed of a pair of cosine and sine modulated filter banks is applied to MC-CDMA data transmultiplexing in the view point of mitigating inter-channel interferences. Exploiting superior capabilities of wavelet properties in composing the filter banks the proposed scheme is capable of compromising inter-channel interference problems better than the conventional DFT-based MC-CDMA due to superior subchannelization effects. To verify the behavior of our proposed MC-CDMA system based on the quadrature filter banks the reverse-link bit error rates with respect to signal-to-noise ratio under Rayleigth fading and additive white Gaussian noise channel environments are computed. The results show an improved system performance over the conventional MC-CDMA in the view point of minimizing interference effects.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2686-2695
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• 1997

The MC-CDMA(multi-carrier code division multiple access) technique is known to be appropriate for high data-rate wireless communications such as mobile multimedia communication due to its robustness to multipath fading and its capability of handing high data rates with a simple one-tap equalizer. In this paepr, the performance of a MC-CDMA cellular system employing antenna arrays at the based station in a fading channel is presented. It is whown that the interference from other users within the cell can be significantly reduced for both reverse link (mobile to base station) and forward link (base station to mobile) using a MC-CDMA with antenna arrays, thus incresig the system's user-capacity. Computer simulations that demonstrate user-capacity improvement of the proposed approach are discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.680-683
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• 2001

본 논문은 대기에 의한 흡수율이 매우 큰 60GHz 대역에서의 전파 특성을 이용하여 근거리 차량간 통신 시스템에 적용하여 시스템을 분석한다. 근거리 차량간 통신에서는 전파환경이 직접파와 지면반사파 그리고 측면 차량, 도로벽면에 의한 다중경로가 존재하는 라이시안 분포의 특성이 존재하며 이러한 특성을 고려하여 밀리미터파 분석에 효율적인 Raytracing방법을 도입하여 차량간 통신 시스템을 분석한다. 또한 차량간 통신은 운전자의 안전성과 연결되어지기 때문에 매우 높은 신뢰성이 요구되어지며 따라서 MC-CDMA/QPSK 방식을 도입하여 시스템의 신뢰성을 확보하였으며 수신 성능 향상을 위한 개선기법으로는 BCH 부호화 기법을 적용하여 시스템의 성능을 비교 분석 한다.

• Communications for Statistical Applications and Methods
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• v.4 no.2
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• pp.333-343
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• 1997

선형회귀분석에서 변수의 선택문제는 최적의 모형을 찾는데 아주 중요한 부분을 차지한다. George와 McCulloch(1993)는 계층적 베이즈 모형과 깁스표본법을 이용하여 선형회귀모형에서 변수를 선택하는 문제를 고려하였다. 이 논문에서는 George와 McCulloch의 모형을 바탕으로 각각의 설명변수가 모형에 포함될 사전확률을 객관적인 기준에 의하여 결정하는 문제를 고려하여 보았다.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.130-133
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• 1999

In the view point of further reducing the inter-symbol interferences studied in our previous paper 〔1〕, a quadrature pair of wavelet-based filter banks that are composed of a pair of cosine and sine modulated filter banks is applied to MC-CDMA transmultiplexing. For that fact, the symbol duration gets twice longer than the one in , 〔1〕, the interference effects due to channel overlapping and Doppler spread can be effectively alleviated while increasing the channel utilization efficiency. Moreover, the well-known wavelet properties are exploited to design the prototype filter in such a way to maintain the size of sidelobes much smaller than those of the FFT, the interference reduction effect can be further obtained. To verify the behavior of our proposed quadrature filter bank based MC-CDMA system, the reverse-link bit error rates with respect to SNR under Rayleigh fading and additive white Gaussian noise channel environments are computed. The results show an improved system performance over the conventional MC-CDMA.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.1
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• pp.110-118
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• 2009

The PB/MC-CDMA(Partial Block Multi Carrier Code Division Multilple Access) system can improve the performance by reducing the ICI(Inter-Code Interference) between users. Also, this system can achieve the frequency diversity gain by avoiding ISI(Inter Symbol Interference). Therefore, the performance of PB/MC-CDMA system is better than that of conventional MC-CDMA(Multi Carrier Code Division Multiple Access) system. However, similarly to other multi-carrier systems, it still has a PAPR(Peak to Average Power Ratio) issue. In this paper, we propose a peak power reduction technique involving optimized spreading code selection without side information for the PB/MC-CDMA. The PB/MC-CDMA system in each block of units reuses the code so the extra code will be remained. This extra code is divided into several groups to calculate the PAPR and solving the PAPR problem by transferring the selected code which has minimum peak power.

• Journal of Advanced Navigation Technology
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• v.5 no.1
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• pp.11-18
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• 2001

In this paper, we evaluated the performance of Orthogonal MC/FH-CDMA system considering the hit of frequency hopping patterns, and obtained the degree of the performance improvement by adopting TCM scheme under frequency selective Rayleigh fading channel. From the performance analysis, it is known that the error performance is improved, since delay time relative to symbol time is reduced as the number of carrier is increased. On the other hand, it is found that BER performance is improved about $5{\times}10^{-2}$ degree by adopting TCM scheme, and higher S/N is required if the QoS of voice (BER = $10^{-3}$) must be achieved.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.6
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• pp.149-157
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• 2011

In this paper, we propose a new DPCM-based transmission scheme for flight data. The amount of the flight data from LRU to MC has been increased due to the emergence and development of avionics systems and functions. It becomes a serious issue for satisfying the hard real-time processing required in the MC. In order to solve this problem, we observed the flight data produced by X-Plane simulator and discovered that the most flight data are moderately varied during flight. Based on this fact, a new data format is suggested by modifying that of ARINC-429 protocol in this paper. And the different value of the flight data is transmitted in the proposed scheme. The simulation results show that the proposed scheme achieves 20% data transfer gain compared to the ARINC-429 based transmission method.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.21 no.2
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• pp.15-24
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• 2015

Background: Many people are suffering from neck and shoulder pain due to muscle weakness, muscle fatigue, lack of exercise and accidents during exercise. In this study we compared the effects of McKenzie method and Mulligan technique method. Method: we randomly selected men(10) and women(10) and they are the 20s students of Busan material K college. We divided for McKenzie exercise group and Mulligan exercise group. McKenzie exercise and mulligan exercise applied cervical area three times a week for three weeks. We compared with pre-experiment and after 1~3 week through measuring the electromyography (EMG) change and neck range of motion (ROM). Results: The changes in the EMG at each exercise group, there was a statistically significant difference in each week. Although there was a significant difference after 1 week between the exercise group, the changes in the neck ROM at each exercise group there was no statistically significant difference. Conclusion: After experiment, EMG and neck ROM were increased in McKenzie exercise group and Mulligan exercise group. But Mulligan exercise group showed the change better than McKenzie exercise group in early stage. We suggest the Mulligan exercise method for recovering in early stage of neck ROM.