• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.154.2-154.2
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• 2008

• Journal of Sensor Science and Technology
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• v.23 no.6
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• pp.392-396
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• 2014

The 2-dimensional silicon vertical Hall devices, which are sensitive to X,Y components of the magnetic field parallel to the surface of the chip, are fabricated using a modified bipolar process. It consists of the thin p-layer at Si-$SiO_2$ interface and n-epi layer to improve the sensitivity and influence of interface effect. Experimental samples are a sensor type K with and type J without $p^+$ isolation dam adjacent to the center current electrode. The results for both type show a more high sensitivity than the former's 2-dimensional vertical Hall devices and a good linearity. The measured non-linearity is about 0.8%. The sensitivity of type J and type K are about 66 V/AT and 200 V/AT, respectively. This sensor's behavior can be explained by the similar J-FET model.

• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.190-193
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• 1991

The monolithically integrated receiver OEIC using InGaAs/InP PIN PD, junction FET's and bias resistor has been fabricated on semi-insulating InP substrate. The fabrication process is highly compatible between PD and self-aligned JFET, and reduction in gate length is achieved using an anisotropic selective etching and a non-planar OMVPE process. The PIN photodetector with a 80 ${\mu}{\textrm}{m}$ diameter exhibits current of less than 5 nA and a capacitance of about 0.35 pF at -5 V bias voltage. An extrinsic transconductance and a gate-source capacitance of the JFET with 4 ${\mu}{\textrm}{m}$ gate length (gate width = 150 ${\mu}{\textrm}{m}$) are typically 45 mS/mm and 0.67 pF at 0 V, respectively. A voltage gain of the pre-amplifier is 5.5.

• Journal of Sensor Science and Technology
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• v.20 no.4
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• pp.260-265
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• 2011

The silicon vertical hall devices are fabricated using a modified bipolar process. It consists of the thin p-layer at Si-$SiO_2$, interface and n-epi layer without $n^+$buried layer to improve the sensitivity and influence of interface effects. Experimental samples are a sensor type I with and type H without p+isolation dam adjacent to the center current electrode. The experimental results for both type show a more high current-related sensitivity than the former's vertical hall devices. The sensitivity of type H and type I are about 150 V/AT and 340 V/AT, respectively. This sensor's behavior can be explained by the similar J-FET model.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.1048-1050
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• 2008

Electric current flow was observed through imogolite film when imogolite ($(HO)_3Al_2O_3SiOH$) was exposed to water molecules and connected to external electrodes. Current flow was due to the bound water on the surface of imogolite. Current flow increased as the pH of the water decreased. The current-voltage (I-V) measurements from a field effective transistor (FET) using $H_2O$/imogolite film revealed that the current carrier in $H_2O$/ imogolite had p-type characteristics, i.e. the carrier was probably $H^+$. The possible mechanism for current transportation in imogolite/water was also suggested in this paper.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.558-562
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• 2006

We have synthesized a new p-type polymer, poly(9,9'-n-dioctylfluorene-alt-phenoxazine) (PFPO), via the palladium catalyzed coupling reaction. The number average molecular weight ($M_n$) of PFPO was found to be 23,000. PFPO dissolves in common organic solvents such as chloroform and toluene. The UV-visible absorption maximum of the PFPO thin film is clearly blue-shifted with respect to that of F8T2, poly-(9,9'-n-dioctylfluorene-alt-bithiophene). The introduction of the phenoxazine moiety into the polymer system results in better field-effect transistor (FET) performance than that of F8T2. A solution processed PFPO TFT device with a top contact geometry was found to exhibit a hole mobility of $2.7{\times}10^{-4}cm^2/Vs$ and a low threshold voltage of -2 V with high on/off ratio(${\sim}10^4$).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.190-195
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• 2000

This paper presents the fabrication of the LNA which is operating at 2.13∼2.16 GHz for IMT-2000 lot-end receiver using series feedback and resistive decoupling circuit. Series feedback added to the source lead of a transistor keep the low noise characteristics and drop the input reflection coefficient of amplifier simultaneously. Also, it increases the stability of the LNA. Resistive decoupling circuit is suitable for input stage matching because a signal at low frequency is dissipated by a resistor in the matching network The amplifier consist of GaAs FET ATF-10136 for low noise stage and VNA-25 which is internally matched MMIC for high gain stage. The amplifier is fabricated with both the RF circuits and self bias circuit on the Teflon substrate with 3.5 permittivity. The measured results of the LNA which is fabricated using above design technique are presented more than 30 dB in gain P$\_$ldB/ 17 dB and less than 0.7 dB in noise figure, 1.5 in input$.$output SWR(Standing Wave Ratio).

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.83-90
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• 2000

A simple low-cost and small size 1.88-198 GHz Band RF power amplifier module is developed for IMT2000 repeater. The power amplifier consists of two stage amplifiers that the first stage amplifier is drive amplifier using discrete type P-HEMT (ATF-34143, 800 micron gate width, Agilent Technologies) and the second is power amplifier with 300Bm 1dB gain compression point using GaAs FET(EFA240D-SOT89, 2400 micron gate width, Excelics Semiconductor). this power amplifier module feature a 29.5dBm 1dB gain compression point, 29.5dB gain, 42dBm 3rd order intercept point(OIP3) and -10dB/-l2dB input/output return loss over the 1880-1980 MHz. This PA module is fully integrated using MIC technology into a small size and design by full nonlinear design technologies. The dimensions of this PA module are 42(L) $\times$ 34(W) mm.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.15-22
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• 1996

FET type $Ca^{2+}$ sensor(Ca-ISFET) was fabricated by micropool and photolithographic method utilizing photosensitive polymer as membrane materials. When OMR-83 negative photoresist was used as membrane material, it gave good sensitivity by micropool method with dioctyladipate as plasticizer but it could not be used in the photolithographic method. When poly(viny1 butyral), PVB was used as membrane material, it gave relatively high sensitivity ($23{\pm}0.2\;mV/decade$) for $Ca^{2+}$ concentration range of $10^{-4}{\sim}10^{-1}\;mole/{\ell}$ by photolithographic method. PVB also provided good adhesion to the pH-ISFET base device without adhesion promoter pretreatment and any plasticizer.

• The Journal of Korean Physical Therapy
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• v.16 no.4
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• pp.38-58
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• 2004

The regain of independent ambulatory ability is a important goal in the rehabilitation program of hemiplegic patient. Not only the function of lower extremity muscles, but also trunk muscles which stabilize extremities and pelvis, are important factors in normal gait. Therefor, it is necessary to develop an effective program which can improve muscle strength and symmetric activity of trunk muscles. The purpose of this study was to evaluate the influence of trunk muscle strengthening by forceful respiratory exercise on the gait asymmetry ratio in hemiplegic patient. 45 Hemiplegic patients due to stroke was randomized in 3 groups, forceful expiratory training(FET), forceful inspiratory training(FIT) and control group. In the experimental groups, ordinary physical therapy with forceful expiratory training and forceful inspiratory training for 20 minutes duration 3 times per week for 6 weeks were respectively performed. In the control group, only ordinary physical therapy was done. Before and after experiments, temporal-spatial gait parameters was measured in all patients. The data of 28 patients who carried out the whole experimental course were statistically analysed. The results of these experiment are as follows : 1. In comparison of difference of single support time asymmetry ratio among 3 groups, the FET group was significantly decreased than the control group (p<.05). 2. In comparison of difference of step length asymmetry ratio among 3 groups, the FIT group was significantly decreased than the control group (p<.05). Based on these results, it is concluded that the forced respiratory exercise program for 6 weeks can be improve the gait asymmetry ratio in hemiplegic patients. Therefore, the forced respiratory exercise is useful to improve the walking ability in hemiplegic patients. Since this study dealt only with the patients who could walk more than 3 meters in distance on floor independently, the further study for evaluating the influence of the forceful respiratory exercise on patients with acute stage stroke and also the development in various methods of use are expected.