• Journal of Sensor Science and Technology
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• v.10 no.5
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• pp.314-319
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• 2001

In this study, the highly sensitive $CaSO_4$:Tm-PTFE TLDs has been fabricated for the purpose of measurement of high energy electron. $CaSO_4$:Tm phosphor powder was mixed with polytetrafluoroethylene(PTFE) powder and moulded in a disk type(diameter 8.5mm, thickness $90mg/cm^2$) by cold pressing. The batch uniformities were average deviation 3.1%. The TLDs were applied to measurement of absorbed dose distribution for high energy electron, the ranges were determined to be $R_{100}=14.5mm$, $R_{50}=24.1mm$ and $R_p=31.8mm$, respectively. The beam flatness were 4.5% as the variation of dose relative to the central axis over the central 80% of the field size at a maximum dose depth in a plane perpendicular to the central axis.

• Journal of Sensor Science and Technology
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• v.7 no.3
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• pp.218-224
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• 1998

2nO and $Al_{2}O_{3}$ powder were weighed in 1 : 1 mole ratio and ball-milled in ethanol for 3 h. Dried mixture were pressed and then sintered at $900^{\circ}C{\sim}1200^{\circ}C$ for 3 h in vacuum($3{\times}10^{-5}$ Torr). According to XRD, remnant ZnO and $Al_{2}O_{3}$ not converted to $ZnAl_{2}O_{4}$ were observed up to $1100^{\circ}C$, which were completely changed to$ZnAl_{2}O_{4}$ ternary compound at $1200^{\circ}C$. Optical bandgap is calculated at 4.75 eV. With increasing sintering temperature, PL spectrums shifted to shorter wavelengths and are appeared 430nm at $1200^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.9 no.1
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• pp.83-89
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• 2000

BST thin films were deposited on the ITO coated glass for using TFELD insulating layer by rf magnetron sputtering method. $O_2/(Ar+O_2)$ mixing ratio was 10%, substrate temperature was changed from R.T. to $500^{\circ}C$, and working pressure was changed from 5 mTorr to 30 mTorr. BST thin films deposited with various conditions were investigated electrical, optical, structural properties, and stoichiometry. The result of investigation was achieved good fabrication condition that substrate temperature of $400^{\circ}C$, and working pressure of 30 mTorr. Relative dielectric constant of 254 at 1 kHz, leakage current density was below $3.3{\times}10^{-7\;}A/cm^2$ at 5\;MV/cm applied electric field, and transmittance was over 82% at visible range.

• Journal of Sensor Science and Technology
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• v.5 no.1
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• pp.63-70
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• 1996

Silicon epitaxial films of submicron level were successfully grown by the RTCVD method. For the growth of silicon epitaxial layers, $SiH_{2}Cl_{2}\;/\;H_{2}$ gas mixtures and various process parameters including $H_{2}$ prebake process were used. The growth conditions were varied to investigate their effects on the interface abruptness of doping profile, the film growth rates and crystalline properties. The crystallinity of the undoped silicon was excellent at the growth temperature of $900^{\circ}C$. The doping profiles were measured by SIMS technique. The abruptness of doping profile would be controlled within about $200{\AA}/decade$ in the structure of undoped Si / $n^{+}-Si$ substrate.

• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.157-163
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• 2011

In this paper, configuration control for the Horizontal Maintenance and driving of the mobile inverted pendulum robot has been studied using ARS(Attitude Refrence System). The inverted pendulum technique is getting attention and there have been many researches on the seg-way since the US. Using its 2 freedom, a mobile inverted pendulum robot can move in various modes and Our robot performs goal reaching ARS. Mobile inverted pendulum robot fall down to the forward or reverse direction to converge to the stable point. Kalman Filter is normally used for the algorithm and numerous research is progressing at the moment. To calculate the attitude in ARS using 2 axis gyro(roll, pitch) and 3 axis accelerometers (x, y, z). In this paper we present a two wheel robot system for an autonomous mobile robot. This paper realized the robot control method which is much simpler but able to get desired performance by using the IMU and PID control.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.689-696
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• 2011

In this paper, we propose the result of PSSK(Phase Silence Shift Keying) modulation scheme that is mixed PSK(Phase Shift Keying) modulation and PPM(Pulse Position Modulation) method. The performance of underwater communication systems are influenced underwater channel characteristics. In particular, delay spread can make ISI(Inter Symbol Interference) because of reverberation and multi path. It degrade the performance of the communication system. Also underwater sensor networks consider about power efficient due to the particularities of their operating environment. PSSK modulation method transmit two orthogonal symbol and using silence period in a period so it can reduce the power. Increasing the distance of between modulation symbols, to enhance the performance of BER(Bit Error Rate) as well as to improve power efficient. The result of sea trial, QPSK modulation BER is $3.19{\times}10^{-1}$ and PSSK modulation BER is $2.89{\times}10^{-1}$.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.348-353
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• 2009

Organic materials reveal the remarkable absorption and high buffer capacity for nutrient. Hence, organic materials need some different nutrient management skill from inorganic one. The objective of this study was to evaluate the effect of EC level of nutrient solution on the yield and quality of cut rose grown in the mixed substrate of coir and perlite. 3 EC levels of nutrient solution was treated, which were 0.7, 1.0, 1.3 times of standard solution (Aichiken solution, Japan) for cut rose hydroponics. EC of the standard solution was changed by season following as 1.4 (Apr.~June), 1.0 (July~Aug.), 1.4 (Sep.~Oct.), and $1.6dS{\cdot}m^{-1}$ (Nov.~Mar.) subsequently. The supply of nutrient solution was controlled by the signal of water potential at -5kPa using frequency domain reflectometry (FDR) sensor. As the results, marketable yield was similar for all treatments until 3rd harvest, but was decreased in high EC level from 4th harvest to 7th harvest as final. 0.7 times of standard solution decreased the ratio of unmarketable rose having short stem below 70cm and increased the ratio of high quality rose having long stem above 91cm. The flower weight and stem diameter of cut rose was higher in the low EC treatment than the others.

• Journal of Bio-Environment Control
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• v.19 no.4
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• pp.240-245
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• 2010

The objective of this study was to determine the effect of different height of drainpipe and growing media soilless cultivated cut rose in container culture. Two experiment were to examine the effect of the drainpipe height and media composition on yield and quality of cut rose, Four different drainpipe height (0, 3, 6, 9 cm) were treated to determine of optimal container type. Yield was the highest at 3 cm drainpipe height, but quality was not significantly affected by drainpipe height. Survival rate of rose was 100%, 100%, 92%, and 92%, respectively. Two different drainpipe height (0, 3 cm) and 7 media composition (pure coir and pelite, and mixed with two media 3 : 1, 2 : 1, 1 : 1, 1 : 2, 1 : 3 v/v) was treated to determine of media composition related to drainpipe height. The supply of nutrient solution was controlled by the signal of water potential at -5 kPa using frequency domain reflectometry (FDR) sensor in mixed coir with pelite 3 : 1, 1 : 1, 1 : 3 (v/v), respectively. Irrigation frequency reduced in high ratio of coir media and 3 cm height of drainpipe. Quality of cut rose except for flower weight and yield until 2nd harvest was not significantly affected by drainpipe height, but yield after 3rd was higher at 3 cm than 0 cm height of darinpipe. In the media composition, yield and qulity of cut rose was increased at high ratio of coir media.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.2
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• pp.54-64
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• 2010

Localization is the most important feature in the sensor network environment because it is a basic element enabling people and things to aware the circumference environment. Existing localization methods can be categorized as either range-based or range-free. While range-based is known to be not suitable because of the irregularity of radio propagation and the additional device requirement. range-free is much appropriated for the resource constrained sensor network because it can actively locate by means of the communication radio. But its location accuracy is just depended on the density of circumference nodes; it is very low in low-density sensor network environment. This paper proposes a mobile object tracking method, named DRTS(Distributed Range-hybrid Tracking Scheme), with combining range-based and range-free. It is optimally making use of the location, communication range, and received signal strength from circumference nodes. Especially, it can greatly improve the mobile tracking accuracy by adapting a new prediction method, named EGP(Estimative Gird Points) into the proposed location estimation method. The simulation results show that our method outperforms the other localization and tracking methods in the tracking accuracy point of view.

• Composites Research
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• v.23 no.3
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• pp.31-36
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• 2010

A new material, carbon-nanofiber/polypyrrole (CNF/PPy) composite films, with different CNF weight ratios were fabricated electrochemically. Compared to the fabrication process based on simple physical mixing, the flexibility of the new film has been improved much better than the previous similar material. Pure PPy films were also fabricated by the new electrochemical process for the comparison of difference. Several SEM images were taken at two locations (electrode-side and solution-side) and at the cross section of the samples. Electrical conductivity of the composite films was measured by the four-probe method. The conductivity of the pure PPy film 0.013cm thick was 79.33S/cm. The CNF/PPy composite film with 5% CNF showed a conductivity of 93S/cm. One with 10% CNF showed a conductivity of 126 S/cm. The conductivity of PPy improves, as the CNF weight ratio increases. The good conductivity of CNF/PPy composites makes them a candidate for a small bending actuator. A bending sensor consists of PPy and PVDF, which can be operated in the air, was designed and the bending deflection was calculated using FEM.