• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.5
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• pp.857-861
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• 2016

In this study, we proposed a new method that can be measure ECG (Electrocardiography) and PPG (Photoplethysmography) in realtime on the site of the wrist for check the state of health in daily life. For convenience measurement of ECG the lead I method was used on the wrist, and omit the reference junction ECG I was measured in the right hand and the left hand of the potential difference. Then the measured electrocardiogram was amplified by the differential amplifier and the signals were passed HPF, LPF, and BPF filters. For removing the PPG's noise from the Motion artifact and temperature, we apply the reflective photoelectric volume pulse wave measurement method using green LED as a light source. The circuits was designed to be able to check the waveform using higher active amplification method at weak signals. For the validation of our device, the measured signals were compared with E2-KIT on same time. The results shows that the error does not exceed the maximum one, most of the data is confirmed to be issued Peak inspection of the same number.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.7 no.2
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• pp.47-54
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• 1982

In this paper, a improved per-channel PCM Coder with 1-bit interpolation is proposed. The coder converts a telephone signal to 15-segments u-law PCM signal of a large dynamic range. The A/D conversion technique of the proposed converter requires a feedback loop around a quantizer operates at high speed, and a accumulater for accumulating the quantized values to provide PCM outputs. To obtain both linear and compressed PCM signals a improved table look-up method is presented. The operations of the proposed converter are certified through the experiments to be good. The experimental circuit comprises TTL logic gates, a resistive D/Z converter and a simple differential amplifier. From the results of the experiments, it is known that the proposed converter has many advantage to be adopted economically for per-channel onverter used in rural area service.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.2
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• pp.109-115
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• 2004

This paper deals with the behaviors of magnetic flux density near down-conductors by lightning currents. The background on the principle of magnetic flux density measurements using the RL self-integrating magnetic field sensor was described. The magnetic flux density measuring device consisting of RL self-integrating magnetic field sensor and differential amplifier was designed and fabricated. The frequency bandwidth of the magnetic flux density measuring system ranges from 200 Hz to 300 KHz and the response sensitivity was 0.126 $\mu$T/㎷ The distributions of the magnetic flux density near down-conductors due to impulse currents with various rise times were analyzed as a parameter of the bonding conditions and materials of conductor and wiring conduits. The magnetic flux density due to impulse currents was inversely proportional to the distance between the down-conductor and measuring point. The amplitude of the magnetic flux density for PVC Pipe with down-conductor was 72 $\mu$T/㎷ at the distance of 1m and was higher than for steel conduits and coaxial cable. Finally the magnetic flux density is increased with increasing the di/dt it and oscillation frequency of lightning currents in this experimental ranges.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1914-1915
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• 2007

The period and strength of the pulse on the radial artery are important physiological factors, and they have been used to diagnosis in both Western and Eastern countries for a long time and has been developed as a unique method of diagnosis at each countries. Recently, there are a lot of systems which can give diagnosis information by recording the pulse wave and analyzing the characteristics of the pulse shape. This study describes the Pulse-Wave Measurement System which is able to measure the pulse wave signal using piezoresistive sensor and the pulse wave signal measured by the developed system is transmitted to a computer on the basis of the USB Driver. It has finally shown the the pulse wave signal measured by the sender is appeared to the host PC in real time. The Pulse-Wave Measurement System used the piezoresistive sensor to measure the pulse wave signal and the differential amplifier(AD620) to amplify the pulse wave signal which is small signal. And it used the ADC to convert analog to digital for the measured analog signal and the interface with a computer. It transmitted the measured pulse signal through USB transmission module to the host computer and Labview tool shows it. This Pulse-Wave measurement system will afford comvenience of detecting pulse wave to user related to oriental medicine.

• International journal of advanced smart convergence
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• v.10 no.1
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• pp.12-23
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• 2021

This paper proposes a low power radio frequency receiver front-end where, in a single stage, single-balanced mixer and voltage-controlled oscillator are stacked on top of low noise amplifier and re-use the dc current to reduce the power consumption. In the proposed topology, the voltage-controlled oscillator itself plays the dual role of oscillator and mixer by exploiting a series inductor-capacitor network. Using a 65 nm complementary metal oxide semiconductor technology, the proposed radio frequency front-end is designed and simulated. Oscillating at around 2.4 GHz frequency band, the voltage-controlled oscillator of the proposed radio frequency front-end achieves the phase noise of -72 dBc/Hz, -93 dBc/Hz, and -113 dBc/Hz at 10KHz, 100KHz, and 1 MHz offset frequency, respectively. The simulated voltage conversion gain is about 25 dB. The double-side band noise figure is -14.2 dB, -8.8 dB, and -7.3 dB at 100 KHz, 1 MHz and 10 MHz offset. The radio frequency front-end consumes only 96 ㎼ dc power from a 1-V supply.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.522-529
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• 2000

We present a new procedure to evaluate the residual life of 1Cr-1Mo-0.25V steel by reversible magnetic permeability. The method is based on the existence of the first harmonics in the differential magnetization around the coercive force. The apparatus is based on the detection of the voltage induced in a coil using a lock-in amplifier tuned to a frequency of the exciting one. Results obtained for the first harmonics and Vickers hardness on the aged samples show that the peak interval of reversible permeability and Vickers hardness decrease as ageing time increases. The correlation between Vickers hardness and the peak interval of the reversible permeability could well be used to evaluate the residual life of 1Cr-1Mo-0.25V steel, nondestructively.

• Journal of Korea Society of Digital Industry and Information Management
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• v.20 no.2
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• pp.63-74
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• 2024

This Paper presents a resistive wideband fully differential low-noise amplifier (LNA) designed using a noise-cancellation technique for TV tuner applications. The front-end of the LNA employs a cascode common-gate (CG) configuration, and cross-coupled local feedback is employed between the CG and common-source (CS) stages. The moderate gain at the source of the cascode transistor in the CS stage is utilized to boost the transconductance of the cascode CG stage. This produces higher gain and lower noise figure (NF) than a conventional LNA with inductor. The NF can be further optimized by adjusting the local open-loop gain, thereby distributing the power consumption among the transistors and resistors. Finally, an optimized DC gain is obtained by designing the output resistive network. The proposed LNA, designed in SK Hynix 180 nm CMOS, exhibits improved linearity with a voltage gain of 10.7 dB, and minimum NF of 1.6-1.9 dB over a signal bandwidth of 40 MHz to 1 GHz.

• Journal of Radiation Protection and Research
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• v.21 no.2
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• pp.139-143
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• 1996

A multi-wire proportional counter with large sensitive area was designed and constructed considering diameter of anode wire. its material and space. A preamplifier connecting detector to main amplifier or counter was also designed and constructed for measurement output pulse from multi-wire proportional counter. The preamplifier was composed of charge-sensitive differential circuit. clipping circuit and amplification circuit. To test the performance of this equipment, terminal output pulse from the preamplifier was measured and compared with noise For these tests $^{239}Pu(360 Bq)\;and\; ^{90}Sr/^{90}Y(250 Bq)$ were used as radiation sources. The noise ingredient contributing to the maximum amplitude(180mV from $^{239}Pu$ and 200 mV from $^{90}Sr/^{90}Y$) was found to be very small(8 mV) Piled up pulse occurring at the output pulse of charge-sensitive differential circuit was measured as an independent pulse since this affected the amplification in the clipping circuit and amplification circuit. This information can be used to improve the loss of measurement due to piled up pulse.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.41-46
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• 2007

A novel post-linearization technique is proposed for CMOS cascode low noise amplifier (LNA). The technique uses dual common gate FETs one of which delivers the linear currents to a load and the other one sinks the $3^{rd}$ order intermodulation currents of output currents from the common source FET. Selective current branching can be implemented in $0.18{\mu}m$ CMOS process by using a thick oxide FET as an IM3 sinker with a normal FET as a linear current buffer. A differential LNA adopting this technique is designed at 2.14GHz. The measurement results show 11dBm IIP3, 15.5dB power gain and 2.85dB noise figure consuming 12.4mA from 1.8V power supply. Compared with the LNA with turning off the IM3 sinker, the proposed technique improves the IIP3 by 7.5 dB.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.12 s.354
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• pp.47-54
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• 2006

This work proposes a dual-channel 6b 1GS/s ADC for ultra wide-band communication system applications. The proposed ADC based on a 6b interpolated flash architecture employs wide-band open-loop track-and-hold amplifiers, comparators with a wide-range differential difference pre-amplifier, latches with reduced kickback noise, on-chip CMOS references, and digital bubble-code correction circuits to optimize power, chip area, and accuracy at 1GS/s. The ADC implemented in a 0.18um 1P6M CMOS technology shows a signal-to-noise-and-distortion ratio of 30dB and a spurious-free dynamic range of 39dB at 1GS/s. The measured differential and integral non-linearities of the prototype ADC are within 1.0LSB and 1.3LSB, respectively. The dual-channel ADC has an active area of $4.0mm^2$ and consumes 594mW at 1GS/s and 1.8V.