• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.693-696
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• 2006

In this study, we made the system to measure variation of blood flow using bio-electrical impedance analysis method. The system, which could measure variation of impedance according to pressure change by artificial pressure, consists of pressure measurement and impedance measurement by 4-electrode method. Pressure measurement splits into semiconducting pressure sensor and electronic circuit for processing output signal. In addition, impedance measurement splits into constant current source circuit and lock-in amplifier for detection impedance signal. We experimented feature of impedance measurement using standard resistance to evaluate the system characteristic. As well as, we experimented to estimate variation of blood flow by measuring impedance and blood flow resistance ratio using mean arterial pressure and variation of blood flow with experimental group. As result of this study, blood flow resistance ratio and variation of blood flow were definitely in inverse proportion and were -0.96776 as correlation coefficient by correlation analysis.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.1
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• pp.21-28
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• 2004

We have demonstrated a low speed weigh-in motion system using FBG sensors and performed field test at a trial road. Technique, called identical chirped grating interrogation, have used for a demodulation relying on the mismatching of two identical broadband chirped gratings. We compensated the fluctuation of LED power and the temperature of sensor and used a lock-in amplifier to reduce effect of noise. We could design a bending plate that the measurement results are independent of position of weight. The FBG sensors weigh-in motion system showed linearity and reproducibility.

• Journal of the Korean Magnetics Society
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• v.7 no.6
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• pp.327-333
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• 1997

We designed and constructed the high frequency magnetic characteristics measurement system to measure core loss, B-H curve, permeability of toroidal ferrite core, amorphous core and various materials for high frequency application. The system consists of universal equipments such as digitizing oscilloscope, signal generator, power amplifier, PC in order to make upgrade easily. The power source is composed of waveform synthesizer and power amplifier ranging from DC to 20 MHz, and output signal H and B from sample core are digitized by oscilloscope with sampling rate 1 GS/ s per channel. Computer controls power source and oscilloscope, reads data from oscilloscope, displays analyzed waveform and saves data with file. The entire procedures finishes within few seconds.

• Journal of Sensor Science and Technology
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• v.26 no.5
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• pp.342-347
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• 2017

We present a precision instrument amplifier (IA) designed for bio-potential acquisition. The proposed IA employs a capacitively coupled instrument amplifier (CCIA) structure to achieve a rail-to-rail input common-mode range and low gain error. A positive feedback loop is applied to boost the input impedance. Also, DC servo loop (DSL) with pseudo resistors is adopted to suppress electrode offset for bio-potential sensing. The proposed amplifier was designed in a $0.18{\mu}m$ CMOS technology with 1.8V supply voltage. Simulation results show the integrated noise of $1.276{\mu}Vrms$ in a frequency range from 0.01 Hz to 1 KHz, 65dB SNR, 118dB CMRR, and $58M{\Omega}$ input impedance respectively. The total current of IA is $38{\mu}A$. It occupies $740{\mu}m$ by $1300{\mu}m$ including the passive on-chip low pass filter.

• Applied Biological Chemistry
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• v.47 no.3
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• pp.300-306
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• 2004

Eight cation or anion-responsive polymer membranes were prepared by a casting procedure employing polyvinyl chloride, Bis (2-ethylhexyl)sebacate and each electroactive material in the ratio of 66 : 33 : 1. The resulting membranes were separately installed onto the sensitive area of the ionic electrodes to produce an 8-channel taste sensor array. The taste sensors of the array were connected to a high-input impedance amplifier and the amplified sensor signals were interfaced to a PC via an A/D converter. The taste evaluation system was applied to a discriminant analysis on six groups of marketed beverages like sikhye, sujunggwa, tangerine juice, ume juice, ionic drink and green tea. When the signal data from the sensor array were analyzed by principal component analysis after normalization, the 1st, 2nd and 3rd principal component explained most of the total data variance. The six groups of the analyzed beverages were discriminated well in the three dimensional principal component space. The half of the five groups of the analyzed beverages was also discriminated in the two dimensional principal component plane.

• Journal of Biomedical Engineering Research
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• v.25 no.3
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• pp.165-169
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• 2004

In Magnetic Resonance Electrical Impedance Tomography (MREIT), we inject current through electrodes placed on the surface of a subject and measure the induced magnetic flux density distribution using an MRI scanner. This requires a constant current source whose output pulses are synchronized with MR pulse sequences. In this paper, we present a design and performance analysis of a current source used in a 3.0T MREIT system. The developed current source was tested using a saline phantom. We found that its performance is satisfactory for the current MREIT system. We suggest future improvements for better SNR(signal-to-noise ratio).

• Journal of Energy Engineering
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• v.13 no.2
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• pp.93-100
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• 2004

The smear media possible to sampling and radiation detection was prepared and evaluated for the surface contamination using indirect method. The films were made by impregnating Cerium Activated Yttrium Silicate (CAYS) in a polysulfone membrane. The membranes used solution as a dimethylformamide (DMF) and methylene chloride (MC), polysulfone as a polymer matrix and CAYS as a inorganic scintillator. The proximity membranes were prepared with single- and double-layered structure. The solidified methods were immersion to the nonsolvent bath such at water and ethanol and solvent evaporation. The measurement of the photon produced by interaction with radiation and inorganic scintillator used a photomultiflier tube (PMT), amplifier, and counter. In the comparison with the low background alpha/beta counter, the counter rate using inorganic scintillator proximity membrane for the $\^$14/C surface contamination was about 50%. Also. the $^3$H counting results revealed that the prepared membranes were efficient to monitor the surface contaminated with the low energy be-ray emitter nuclides.

• Composites Research
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• v.31 no.5
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• pp.238-245
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• 2018

The hydrodynamic ram (HRAM) phenomenon is one of the main types of ballistic battle damages of a military aircraft and has great importance to airframe survivability design. The HRAM effect occurs due to the interaction between the fluid and structure, and damage can be investigated by measuring the pressure of the fluid and the dynamic strains on the structure. In this paper, HRAM test of a composite T-Joint was performed using a ram simulator which can generate HRAM pressure. In addition, calibration tests of PVDF sensor were performed to determine the circuit capacitance and time constant of the measurement system. The failure behavior of the composite T-Joint due to HRAM pressure was examined using the strain gauges and a PVDF sensor which were attached to the surface of the composite T-Joint.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.2
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• pp.217-224
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• 2008

Trusses are found in many common structures such as bridges and buildings. The truss is a fundamental design element in engineering structures and it is important for an engineer to apply the truss design to engineering structures by understanding the mechanics of truss element. In an experimental course, the experiment selves as an example of the usefulness of the Wheatstone bridge in amplifying the output of a transducer. With the apparatus described here, it is possible to obtain experimental measurements of forces in a truss member which agree within errors to predictions from elementary mechanics. The apparatus is inexpensive, easy to operate, and suitable as either a classroom demonstration or student laboratory experiment. This device is a small table-top experiment. The conventional strain measuring device is costly and complicated - it is not simple to understand its structure. Hence, strain gage and the A/D converter are assembled to come up with a load and a strain measuring device. The device was tested for measuring the strain in a loaded specimen and the results were compared to those predicted by theory of mechanics.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.211-212
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• 2011

플라즈마를 제어하기 위해서는 플라즈마의 온도, 밀도, 에너지 분포등과 같은 플라즈마의 특성을 정확히 측정할 수 있어야한다. 핵융합발전에서는 플라즈마를 발생하기 위하여 플라즈마의 온도, 밀도 등 각종 변수들을 시공간적으로 계측, 분석할 수 있는 진달설비를 사용하고 있으며, 정확한 플라즈마 제어와 측정을 위한 새로운 진단기술을 개발하고 있다. 그리고 중요한 변수중에 하나인 플라즈마 이온온도를 측정하기 위해 중성입자 검출법이 잘 알려져 있다. 이 실험은 수소 중성입자가 토카막 내부의 플라즈마 이온과 충돌하면서 생성된 고속 중성입자의 에너지를 분석하는 실험이다. 본 연구의 실험방법은 수소 중성입자를 이온빔 장치에서 이온화 시킨 후 자체 제작한 가속기를 통하여 가속시켜 에너지 특성을 분석을 하는 것이다. 본 연구의 실험장치로 에너지 교정용 100 keV 이온빔 소스를 제작 하였고 이온빔 장치 내부에 수소기체를 주입하고 기체방전을 일으켜 플라즈마를 발생시켰다. 이온빔 외부에는 팬을 설치하고 전도성이 강한 물 대신 전도성이 약한 오일을 사용하여 냉각 하였다. 이온빔 장치와 결합될 이온 가속장치는 지름 300 mm, 두께 2 mm의 원형 구리판을 여러층으로 쌓아 전극으로 제작하였고 전극과 전극 사이에서 코로나 방전과 스파크를 방지하기 위해 전극 둘레에 코로나링을 설치 하였다. 또한 전극 사이마다 1G${\Omega}$의 저항을 설치한 후 고전압을 생성하여 이온 가속 효율을 증대시켰다. 진공시스템으로는 Alcatel사의 CFF100 터보분자 펌프와 우성진공사의 MVP24 진공로타리펌프를 결합하여 사용하였으며, 진공도측정은 Alcatel사의 ACS1000 장치를 사용하였다. 고진공후 고속 중성입자의 이온화와 에너지 측정을 위한 전하교환기를 설치하였다. 전하교환기로는 진공시스템을 별도로 설치하고 비용이 비교적 많이 드는 기체형 전하교환기 대신 소형화가 가능하고 유지보수가 좋은 고체형 전하교환기 제작하여 실험 하였다. 전하교환기에서 이온화된 고속 중성입자가 전기장이나 자장에 영향을 받았을때 에너지분포를 디텍터를 통해 측정하였다. 즉, 이온화된 중성입자의 에너지가 실리콘 다이오드를 통해 전압 펄스 신호로 변환되고 이차 증폭기를 통해 전압 펄스 신호들이 증폭한다. 에너지 측정을 위한 디텍터는 소형화가 가능하고 비용이 비교적 적게 드는 실리콘 다이오드를 설치하였다. 본 연구결과 중성입자 에너지 분석 장치가 실제 핵융합 장치의 플라즈마 이온온도와 특성 측정에 적용할 수 있으며, 앞으로 개발될 여러 형태의 응용 플라즈마 발생장치의 플라즈마 진단에 이용될 것으로 기대한다.