• Journal of Biomedical Engineering Research
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• v.22 no.2
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• pp.197-204
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• 2001

• JSTS:Journal of Semiconductor Technology and Science
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• v.17 no.3
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• pp.438-445
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• 2017

This paper presents a low-power high-resolution band-pass ${\Sigma}{\Delta}$ ADC for accelerometer applications. The proposed band-pass ${\Sigma}{\Delta}$ ADC consists of a high-performance 6-th order feed-forward ${\Sigma}{\Delta}$ modulator with 1-bit quantization and a low-power, area-efficient digital filter. The ADC is fabricated in 180 nm 1P6M mixed-signal CMOS process with a die area of $5mm^2$. This high-resolution ADC got 90 dB peak signal to noise plus distortion ratio (SNDR) and 96 dB dynamic range (DR) over 4 kHz bandwidth, while the intermediate frequency (IF) is shifting from 100 KHz to 200 KHz. The power dissipation of the chip is 5.6 mW under 1.8 V (digital)/3.3 V (analog) power supply.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.229-239
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• 2009

Orthogonal frequency division multiplexing (OFDM) has been adopted as a standard for various high data rate wireless communication systems due to the spectral bandwidth efficiency, robustness to frequency selective fading channels, etc. However, implementation of the OFDM system entails several difficulties. One of the major drawbacks is the high peak-to-average power ratio (PAPR), which results in intercarrier interference, high out-of-band radiation, and bit error rate performance degradation, mainly due to the nonlinearity of the high power amplifier. This paper reviews the conventional PAPR reduction schemes and their modifications for achieving the low computational complexity required for practical implementation in wireless communication systems.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1860-1862
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• 2004

It is widely known that the ultra high frequency (UHF) method that detects the electromagnetic wave of the PD pulses in the gas insulated space is one of the most competitive methods for its high sensitivity. From the above point of view, this paper describes the characteristics of GIS PD signals measured with ultra wide band (UWB) GIS PD detecting system in which PD signals are detected into the dual UHF band. The UWB PD detection system consists of the UWB UHF coupler, the UWB low noise amplifier (LNA) and the oscilloscope. The dual bands for PD signals are 0.5-2GHz(full band) and 1-2GHz(high band). As results, it was found that the partial discharges of each defect have their own characteristic pattern and the ratio of High band to Full band increases with gas pressure.

• Proceedings of the KIEE Conference
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• 2004.11d
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• pp.63-66
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• 2004

It is widely known that the ultra high frequency (UHF) method that detects the electromagnetic wave of the PD pulses in the gas insulated space is one of the most competitive methods for its high sensitivity. From the above point of view, this paper describes the characteristics of GIS PD signals measured with ultra wide band (UWB) GIS PD defecting system in which PD signals are defected into the dual UHF band. Thc UWB PD detection system consists of the UWB UHF coupler, the UWB low noise amplifier (LNA) and the oscilloscope. The dual bands for PD signals are 0.5-2GHz(full band) and 1-2GHz(high band). As results, it was found that the partial discharges of each defect have their own characteristic pattern and the ratio of High hand to Full band increases with gas pressure.

• ETRI Journal
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• v.40 no.6
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• pp.699-713
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• 2018

Orthogonal frequency division multiplexing (OFDM) has been the overwhelmingly prevalent choice for high-data-rate systems due to its superior advantages compared with other modulation techniques. In contrast, a high peak-to-average-power ratio (PAPR) is considered the fundamental obstacle in OFDM systems since it drives the system to suffer from in-band distortion and out-of-band radiation. The partial transmit sequence (PTS) technique is viewed as one of several strategies that have been suggested to diminish the high PAPR trend. The PTS relies upon dividing an input data sequence into a number of subblocks. Hence, three common types of the subblock segmentation methods have been adopted - interleaving (IL-PTS), adjacent (Ad-PTS), and pseudorandom (PR-PTS). In this study, a new type of subblock division scheme is proposed to improve the PAPR reduction capacity with a low computational complexity. The results indicate that the proposed scheme can enhance the PAPR reduction performance better than the IL-PTS and Ad-PTS schemes. Additionally, the computational complexity of the proposed scheme is lower than that of the PR-PTS and Ad-PTS schemes.

• Journal of Oriental Neuropsychiatry
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• v.19 no.3
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• pp.45-54
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• 2008

Objective: To treat psychogenic headache patients, doctors have to amplify on the headache caused by emotional stress to patients, and assist the patients to cope with difficulties. So, we investigated HRV of the headache patients caused by Chiljungsang and would like to apply to the clinical treatment. Method: Our study measured time and frequency domain HRV indicies(5-min resting study) of 123 headache patients caused by emotional stress. Standardized tests of HRV allow a quantitative estimation of autonomic nervous system function. Results & Conclusions: 1. The study classed as aspects of the head pain showed the differences in RMS-SD(square root of mean squared difference of successive NN intervals) band, HF(high frequency) band significantly. 2. The male headache patients showed higher all the indicies except heart rate compared to the female patients, significantly in SDNN(standard deviation of NN interval), TP(total Power), HF band. 3. As the patients grow older, SDNN, RMS-SD band was lower and LF(low frequency) band, LF/HF ratio higher significantly. The beginning age lower, SDNN, RMS-SD band was higher significantly. The duration of the disease longer, LF band, LF/HF ratio was higher significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.2
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• pp.209-216
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• 2013

In this paper, we design and analyze digital retrodirective array antenna (RDA) system in 60GHz wireless communication for low power consumption and high quality. Digital RDA can automatically make beam toward source without information about the direction of incoming signal, this system is able to do low power communication thanks to increased signal to interference noise ratio (SINR) because making the beam toward source can reduce interference signals. The frequency offset seriously arises when millimetric wave band like 60GHz is used to communicate for high-speed transmission. The proposed system is robustly designed to frequency offset through designing digital phase lock loop in order to solve the problem of frequency offset. In this paper, we analyze the performance of the proposed system according to the number of array antenna and frequency offset. striking space.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1649-1651
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• 2002

Ultra-wide bandwidth (UWB) detection method has been widely used as a front end detection scheme for the ultra-high frequency (UHF) partial discharge (PD) monitoring systems. A broad-band video detector module was developed and characterized for the UHF UWB PD detection systems. The useable bandwidth of the module is more than 2 GHz and it is optimized for 50-ohm systems. The detection sensitivity and dynamic range of the module were characterized by using a known ns-width RF pulses of GHz range. The dynamic range is more than 6-decades and the module can detect pulsed RF signals down to 1 nW. The detector module can eliminate expensive equipment such as high speed oscilloscopes and radio frequency (RF) spectrum analyzers. Therefore, it enables one to use slow speed data acquisition systems for the PD monitoring at the UHF range. The detector module was used to detect real PDs of about <3 pC. The module converts the UWB PD signals into a low-bandwidth video signal with a high signal-to-noise ratio.

• The Journal of Korean Medicine
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• v.28 no.2 s.70
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• pp.80-92
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• 2007

Objectives : Functional dyspepsia (FD) is one of the most common gastrointestinal diseases. Nevertheless, there are many unknown mechanisms of autonomic functioning in FD patients. This study was designed to investigate the relationship between FD and biosignals from heart rate variability (HRV) and Yangdorak diagnosis. Methods : 32 patients (22 female, 10 male; mean age 40) and 32 healthy volunteers (21 female, 11 malemean; age 38) participated in this study. First gastrointestinal symptoms rating scale (GSRS) was assessed by questionnaires in both groups to evaluate the types of gastrointestinal symptoms. Second, HRV and Yangdorak diagnosis were measured in both groups. Results : 1. The FD group in this study mainly had the complaint of 'bloating' symptoms. 2. There was statistically no significant difference between Yangdorak (total average and 24 acupoints) and HRV values except logarithmic low-frequency band (lnLF) and total power (TP) in frequency domain. 3. There was statistically no significant relationship between HRV and Yangdorak in either group. However, most Yangdorak values were positively related with some HRV values (low-frequency, low-frequency/high-frequency ratio and high-frequency, etc) in the control group. Conclusions : FD patients had relatively lesser sympathetic domain than healthy subjects, indicated by decreased lnLF and TP. Particularly, there were positive relationships and significant differences between Yangdorak and HRV in young healthy subjects. This suggests that biosignals from HRV may be a useful method that can differentiate FD from healthy state in those of young age.