• The Korean Journal of Pain
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• v.2 no.2
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• pp.145-154
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• 1989

Pain is a common and important clinical symptom, and treatments aimed at relieving pain have a central position in medical practice. Recently Transcutaneous Electrical Nerve Stimulation (TENS) has been effectively used to control acute and chronic conditions that produce pain. But the mechanism of analgesia resulting from TENS remains obscure. In order to investigate the analgesic effect of TENS and it's action mechanism, TENS was applied in 40 rabbits with different frequencies, low frequency (2Hz) and high frequency (100Hz), for 20 minutes. And the pain threshold was measured by the temperature before and after stimulation, and an attempt was made to antagonize the stimulation effect with naloxone pretreatment (0.4 mg/kg) The results are as follows: 1) Both low frequency and high frequency TENS resulted in increasing the pain threshold significantly (Both p<0.01). 2) Naloxone pretreatment could antagonize the effect of increasing the pain threshold with low frequency TENS significantly (p<0.01), but not with high frequency TENS. Plasma beta-endorphin was measured by radioimmunoassay using an Beta-Endorphin Kit (Immunonuclear Corporation, Stillwater, Minnesota, USA) and Automatic Gamma Scintillation Counter (Micromedic System 4/2000) before and after stimulation. An attempt was made to reverse the stimulation effect with naloxone pretreatment (0.4 mg/kg). The results are as follows: 1) Low frequency TENS resulted in increasing the level of plasma beta.endorphin significantly (p<0.01), but high frequency TENS did not. 2) Naloxone pretreatment could reverse the effect of increasing the plasma beta-endorphin level with low frequency TENS significantly (p<0.01).

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.4
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• pp.11-17
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• 2001

In this paper, we propose a polarity decision carrier recovery algorithm for high order QAM(Quadrature Amplitude Modulation), which has robust and large frequency acquisition performance in the high order QAM modem. The proposed polarity decision PD(Phase Detector) output and its variance characteristic are mathematically derived and the simulation results are compared with conventional DD(Decision-Directed) method. While the conventional DD algorithm has linear range of $3.5^{\circ}{\sim}3.5^{\circ}$, the proposed polarity decision PD algorithm has linear range as large as $-36^{\circ}{\sim}36^{\circ}$ at ${\gamma}-17.9$. The conventional DD algorithm can only acquire offsets less than ${\pm}10\;KHz$ in the case of the 256 QAM while an analog front-end circuit generally can reduce the carrier-frequency offset down to only ${\pm}100\;KHz$. Thus, in this case additional AFC or phase detection circuit for carrier recovery is required. But by adopting the proposed polarity decision algorithm, we can find the system can acquire up to ${\pm}300\;KHz$at SNR = 30dB without aided circuit.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.38 no.8
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• pp.62-71
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• 2001

This paper presents a design of the real-time digital image enhancement preprocessor for CMOS image sensor. CMOS image sensor offers various advantages while it provides lower-quality images than CCD does. In order to compensate for the physical limitation of CMOS sensor, the spatially adaptive contrast enhancement algorithm was incorporated into the preprocessor with color interpolation, gamma correction, and automatic exposure control. The efficient hardware architecture for the preprocessor is proposed and was simulated in VHDL. It is composed of about 19K logic gates, which is suitable for low-cost one-chip PC camera. The test system was implemented on Altera Flex EPF10KGC503-3 FPGA chip in real-time mode, and performed successfully.