• Journal of Sensor Science and Technology
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• v.12 no.2
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• pp.57-65
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• 2003

When a vision chip for edge detection using CMOS process is designed, there is a necessity to implement local light adaptive-function for detecting distinctive features of an image at a wide range of light intensities. Local light adaptation is to achive the almost same output level by changing the size of receptive-fields of the local horizontal cell layers according to input light intensities, based on the lateral inhibitive-function of the horizontal cell. Thus, the almost same output level can be obtained whether input light intensities are much or less larger than background. In this paper, the horizontal cells using a resistive network which consists of p-MOSFETs were modeled and analyzed, and the local light adaptive-mechanism of the designed vision chip using the resistive network was verified.

• Journal of Sensor Science and Technology
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• v.12 no.2
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• pp.88-94
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• 2003

Electromyogram (EMG) is the bioelectric signal induced by motor nerves. Analyzing EMG with the movement produced by muscle contraction, we can provide input commands to a computer as a man-machine interface as well as can evaluate the patient's motional abnormality. In this paper, we developed an integrated miniaturized device which acquires and transmits the surface EMG of an interested muscle. Developed system measures $60{\times}40{\times}25mm$, weighs 100g. Using an amplifier circuitry on the electrodes and the radio frequency transmission, the developed system dispenses with the use of cables among the electrodes, amplifier, and the post processing system (personal computer). The wiring used in conventional systems can be obstacle for natural motion and source of motion artifacts. In results, the developed system improves not only the signal-to-noise ration in dynamic EMG measurement, but also the user convenience. We propose a new human-computer interface as well as a dynamic EMG measurement system as a possible application of the developed system.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.466-475
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• 1997

In this paper, an implantable middle ear hearing aids using an electromagnetic transducer which consists of a tiny coil and a magnet is designed, and objective design method to implement a vibrator of the electromagnetic type transducer is proposed. Sound characteristic of the electromagnetic type vibrator is excellent but power transfer rate is lower than that of a ceramic type. To improve power transfer efficiency of system, external and inner part of a middle ear system is designed using FM transmission method. We implemented an experimental set of the designed transducer, inner part, and outer part. Then, we measured vibration characteristics of a metal strip and a temporal bone of a dead body. As the results, we confirmed the advantage of FM method and showed that designed transducer could effectively transmit vibration of amplified input sound pressure to ossicle.

• Journal of Sensor Science and Technology
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• v.6 no.6
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• pp.491-499
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• 1997

We fabricated the ceramic PLT tablet which was composed of 5, 10 and 15 mol% lanthanum concentration and thin film PLT to develope pyroelectric materials, and investigated their characteristics. Using TG/DTA, we determined calcination and sintering temperature to sinter the PLT completely and to prevent volatilization of the Pb components. The calcination and sintering temperature were $850^{\circ}C$, $1150^{\circ}C$ respectively, and there was a lot of mass loss at higher sintering temperature. By measuring temperature-dielectric constant characteristics of ceramic tablet we investigated dielectric constant characteristics depends on La concentration. The Curie point of PLT with 5, 10 and 15 mol% lanthanum concentration were $330^{\circ}C$, $269^{\circ}C$ and $210^{\circ}C$ respectively. Using PLT ceramic tablet we observed IR detection characteristics, and then deposited PLT thin film by rf magnetron sputtering. We verified that PLT thin film fabricated with completely sintered PLT target had the same structure to target by investigating lattice constant and optical transparency.

• Journal of Sensor Science and Technology
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• v.4 no.3
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• pp.37-42
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• 1995

The PLT thin films on MgO substrate have been fabricated by RF magnetron sputtering and the dependence of properties on fabrication conditions have been studied. The PbO-rich target was used and the optimum fabrication conditions of the PLT thin films were such that substrate temperature, working pressure, $Ar/O_{2}$ ratio, and rf power was $640^{\circ}C$, 10 mTorr, 10:1, and $1.7\;W/cm^{2}$, repectively. In these conditions, the PLT thin film showed the deposition rate of $62.5\;{\AA}/min$, the Pb/Ti ratio of 1/2, and the dielectric constant of 200. The PLT thin film showed good c-axis orientation and crystalinity according to XRD and SEM analysis.

• Journal of Sensor Science and Technology
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• v.20 no.1
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• pp.19-24
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• 2011

Brain disorders such as epilepsy is a condition that affects an estimated 2.7 million Americans, 50,000,000 worldwide, approximately 200,000 new cases of epilepsy are diagnosed each year. Of the major chronic medical conditions, epilepsy is among the least understood. Scientists are conducting research to determine appropriate treatments, such as the use of drugs, vagus nerve stimulation, brain stimulation, and Peltier chip-based focal cooling. However, brain stimulation and Peltier chip-based stimulation processes cannot effectively stop seizures. This paper presents simulation of a novel heat enchanger network(HEN) technique designed to stop seizures by using a neural cooling probe to stop focal and spontaneous seizures by cooling the brain. The designed probe was composed of a U-shaped tube through which cold fluid flowed in order to reduce the temperature of the brain. The simulation results demonstrated that the neural probe could cool a 7 $mm^2$ area of the brain when the fluid was flowing atb a velocity of 0.55 m/s. It also showed that the neural cooling probe required 23 % less energy to produce cooling when compared to the Peltier chip-based cooling system.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.136-143
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• 2013

In the study, novel blood pressure estimation method was proposed to improve the accuracy of oscillometric method. The proposed algorithm estimated the blood pressure by comparing and analyzing the point variation aspect of dicrotic notch on pulsating waveform during each cardiac cycle. The waveforms of each cardiac cycle were extracted by maximum points. The extracted pulsating waveforms were applied by re-sampling, end-matching, and normalization. The systolic and diastolic blood pressures were estimated by point variation aspect of dicrotic notch. The blood pressures, which were estimated from proposed algorithm, were compared and analyzed by blood pressures from oscillometric methods and auscultation. The systolic blood pressure from oscillometric methods were +0.88 mmHg more than proposed algorithm, and 1.875 less than the diastolic blood pressures from proposed algorithm. The systolic and diastolic blood pressures from auscultation were 2.89 mmHg and 3.44 mmHg less than the blood pressures from proposed algorithm. As the errors between blood pressures from proposed algorithm, oscillometric method and auscultation were less than 5 mmHg, the proposed algorithm was effective.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.150-155
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• 2013

Recently, various hearing aids are developed to overcome hearing loss. There are available hearing aids, such as air conduction hearing aid, implantable middle ear hearing aid and so on. But air conduction hearing aid is inconvenience caused by howling, and ossicle chain driving type implantable middle ear hearing aid has some week point due to problem of possible nercobiosis of coupling spot along incus long process. In recent years, in order to improve these shortcomings round window (RW) driving hearing aid has been paying attention. In this paper, the physical cochlear model is proposed for a performance evaluation of the RW driving hearing aids of a transducer. In order to verify an experiment proposed on a performance of physical cochlear model, the transducer which has ossicles characteristics is used. By measuring and comparing the frequency characteristics of transducer with ossicles and human temporal bone, performance of physical cochlear model was verified. As from the result of experiment, it is expected that an implemented cochlear model is useful for evaluating characteristics of RW transducer.

• Journal of Sensor Science and Technology
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• v.22 no.2
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• pp.130-135
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• 2013

This study proposed a noble process to fabricate TSV (Through Silicon Via) structure which has lower cost, shorter production time, and more simple fabrication process than plating method. In order to produce the via holes, the Si wafer was etched by a DRIE (Deep Reactive Ion Etching) process. The via hole was $100{\mu}m$ in diameter and $400{\mu}m$ in depth. A dielectric layer of $SiO_2$ was formed by thermal oxidation on the front side wafer and via hole side wall. An adhesion layer of Ti and a seed layer of Au were deposited. Soldering process was applied to fill the via holes with solder paste and metal powder. When the solder paste was used as via hole metal line, sintering state and electrical properties were excellent. However, electrical connection was poor due to occurrence of many voids. In the case of metal powder, voids were reduced but sintering state and electrical properties were bad. We tried the via hole filling process by using mixing solder paste and metal powder. As a consequence, it was confirmed that mixing rate of solder paste (4) : metal powder (3) was excellent electrical characteristics.

• Journal of Sensor Science and Technology
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• v.27 no.1
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• pp.55-58
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• 2018

Low-cost and large-scale fabrication method of nanohole array, which comprises nanoscale voids separated by a few tens to a few hundreds of nanometers, has opened up new possibilities in biomolecular sensing as well as novel frontier optical devices. One of the key aspects of the nanohole array research is how to control the hole size following each specific needs of the hole structure. Here, we report the extensive study on the fine control of the hole size within the range of 500-2500 nm via surface-catalyzed chemical deposition. The initial hole structures were prepared via conventional photo-lithography, and the hole size was decreased to a designed value through the surface-catalyzed chemical reduction of the gold ion on the predefined hole surfaces, by simple dipping of the hole array device into the aqueous solution of gold chloride and hydroxylamine. The final hole size was controlled by adjusting reaction time, and the optimal experimental condition was obtained by doing a series of characterization experiments. The characterization of size-controlled hole array was systematically examined on the image results of optical microscopy, field emission scanning electron microscopy(FESEM), atomic-force microscopy(AFM), and total internal reflection microscopy.