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Noncoherent UWB 시스템을 위한 펄스 반복 전송 기반의 선택적 검출 기법
김재운(Jaewoon Kim),박영진(Youngjin Park),이순우(Sun woo Lee),이재진(Jaejin Lee),서철헌(Chulhun Seo),신요안(Yoan Shin) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.7
In this paper, We propose the selective detection scheme based on pulse repetition considering Bit Error Rate (BER) performance and complexity of noncoherent Ultra Wide Band (UWB) systems. To consider system complexity, the proposed scheme transmits the UWB signals by pulse repetition at the transmitter, like the conventional Pulse Repetition Coding (PRC) However, to effectively improve BER performance of the system, the proposed scheme performs selective detection by estimating the Signal-to-Noise Ratio (SNR) of the received pulse-repeated signal at the receiver. Hence, the proposed scheme effectively improves BER performance of the noncoherent UWB systems without increase of the system complexity, as compared to the conventional PRC algorithm.
김재운(Jaewoon Kim) 물리치료재활과학회 2021 Physical therapy rehabilitation science Vol.10 No.2
Objective: This study covered the effect of stabilization exercise on muscle activity, shoulder painanddisability index(SPADI)oftheelderly people with chronic shoulder pain by tele-rehabilitation village hall in rural area. Design: A randomized controlled trial. Methods: The study subjects are 29 elders with chronic shoulder pain aged over 65-year-old who reside in the rural area (experimental group: 14 elders and control group: 15). The elderly people in the experimental group were asked to perform shoulder stabilization exercise 60 minutes per one time for 4weeks and three times in a week and the others in the control group were asked to receive education related to pain management forthe initial one time. Before and after the experiment, we measured the subjects’ muscle activity of upper trapezius, serratus anteriorand the lower trapezius. In addition, SPADI is measured through the questionnaire. Results: Compared to the control group, the experimental group showed significant differences in the muscle activity of the threemuscles (upper trapezius, serratus anterior, lower trapezius), and SPADI. Conclusions: It is found that shoulder stabilization exercise is effective in muscleactivity, pain and ability of the elderly peoplethrough tele-rehabilitation service. This study should be used for improving the quality of the elderly people’s lives through activetele-rehabilitation service for areas where have poor medical benefits.
OFDM 신호의 PAPR 감소를 위한 효과적인 Clipped Companding 기법
김재운(Jaewoon Kim),신요안(Yoan Shin) 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.10C
본 논문에서는 OFDM (Orthogonal Frequency Division Multiplexing) 신호의 PAPR (Peak-to-Average Power Ratio)을 효과적으로 감소시키기 위한 Clipped Companding 기법을 제안한다. 제안된 기법은 시스템의 복잡도와 비트오율 (Bit Error Rate; BER) 성능 측면을 모두 고려하기 위해, 기본적으로 Companding 기법을 기반으로 하고 Clipping과 Companding 기법이 순차적으로 결합된 두 단계로 구성된다. 제안된 기법의 첫번째 단계에서는 시스템의 BER 성능에 영향을 미치지 않을 정도의 피크 신호들을 잘라내게 되고, 두번째 단계에서는 Wang이 제안한 μ -law Companding 기법을 사용하여 효과적으로 PAPR을 감소시키게 된다. 모의실험 결과, 제안된 Clipped Companding 기법은 기존의 μ -law Companding 기법에 비해 PAPR을 좀 더 감소시킬 수 있으며 동시에 시스템의 BER 성능은 거의 동일하게 유지시킬 수 있음을 확인할 수 있었다. In this paper, we propose a companding scheme to effectively reduce PAPR (Peak-to-Average Power Ratio) of the OFDM (Orthogonal Frequency Division Multiplexing) signals. The proposed scheme is basically based on the companding scheme to consider both complexity and Bit Error Rate (BER) performance, and composed of the clipping followed by the companding scheme. In the first step of the proposed scheme, some of peak signals which do not influence the BER even without them, are clipped. In the second step, the proposed scheme utilizes the μ-law companding to effectively reduce the PAPR. Simulation results show that the proposed clipped companding scheme can provide more PAPR reduction without degradation of the BER performance, as compare to the conventional μ-law companding.
고출력 증폭기의 비선형 왜곡 특성에 강인한 Companding 기법
김재운(Jaewoon Kim),한승우(Seungwoo Han),신요안(Yoan Shin) 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.11C
본 논문에서는 고출력 증폭기 (High Power Amplifier; HPA)의 비선형 특성에 관계없이 시스템의 비트오율 (Bit Error Rate; BER) 성능을 유지하면서 동시에 효율적으로 PAPR (Peak-to-Average Power Ratio)을 감소시킬 수 있는 CCP (Companding Combined with Predistorter) 기법을 제안한다. 제안된 CCP 기법은 기존에 본 저자들이 제안한 Companding 기법이 가지고 있는 Compression 특성과 HPA의 비선형 왜곡 특성에 의해 발생되는 전송 신호의 왜곡으로 인해 나타나는 시스템의 BER 성능 열화를 보완하기 위해 Predistorter를 기존의 Companding 기법에 결합하였다. 따라서, 제안된 CCP 기법은 HPA의 비선형 특성에 관계없이 효율적으로 PAPR을 감소시킬 수 있으며 동시에 시스템의 BER 성능도 유지시킬 수 있는 PAPR 감소 방식이라고 할 수 있다. 모의실험 결과, 제안된 CCP 기법은 TD (Total Degradation) 측면에서 Predistorter를 고려한 Clipping 기법과 Wang이 제안한 Companding 기법에 비해 모든 변조방식에서 가장 낮은 TD 성능을 나타내고 있음을 확인하였다. In this paper, we propose a CCP (Companding Combined with Predistorter) scheme that maintains BER (Bit Error Rate) performance of systems, while effectively reducing PAPR (Peak-to-Average Power Ratio) of OFDM (Orthogonal Frequency Division Multiplexing) signals, independent of nonlinear property of HPAs (High Power Amplifiers). The proposed CCP scheme combines the conventional companding scheme proposed by the authors with the predistorter, in order to prevent degradation of BER performance caused by signal distortion from nonlinear property of the HPA and the compression property of the companding scheme. Hence, the proposed scheme effectively reduces the PAPR and simultaneously maintains the BER performance, independent of nonlinear property of the HPA. Simulation results showed that the proposed CCP scheme provides the lowest total degradation for all the modulations, when comparing with the companding scheme proposed by Wang and the clipping scheme.