• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.07a
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• pp.104-109
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• 2001

A 355 nm (3.5 eV) neodymium:yttrium aluminum gamet laser, produced by a harmonic generator, was used to create silver metallic particles as seeds for nucleation in photosensitive glass containing Ag+ and Ce3+ ions. The pulse width and frequency of the laser were 8 ns and 10 Hz, respectively. Heat treatment was conducted at 570 C for 1 h, following laser irradiation, to produce crystalline growth, after which a LiAlSi3O8 crystal phase appeared in the laser-irradiated Li2O A1203 SiO2 glass. For the Present study, we compared the effect of laser-induced crystallization on glass crystallization with that of spontaneous crystallization by heat treatment.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.43-46
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• 2000

Nd:YAG laser of 355 nm wavelength, which amounts to 3.5 eV, produced by a harmonic generator was used to create Ag metallic particles as seeds for nucleation in photosensitive glass containing $Ag^+$ and $Ce^{3+}$ . The pulse widths and frequency of the laser were 8ns and 10 Hz, respectively. For crystalline growth, heat-treatment following laser irradiation was carried out at $570^{\circ}C$ for 1h. Then, the $LiAlSi_3O^8$ crystal phase appeared in the laser irradiated lithium aluminum silicate glass. We present the effect of laser-induced nucleation compared with spontaneous nucleation by heat treatment fur crystallization in the glass.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.7 no.2
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• pp.109-115
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• 2013

In this paper, we developed pressure mesuring system for powered wheelchair and tried to validate the usefulness of developed system by pressure measuring experiment with 3D motion analysis. This system consist of 64ch seat FSR(Force Sensitive Resistance) sensor unit, 30ch*2 armchair FSR sensor unit, analog and digital hardware board, 2ch rotary encoder unit and realtime signal processing & display S/W. And each data acquired from this system has sampling frequency of 12bit, 10Hz. Pressure measuring experiment for 10 persons who use wheelchair in real life was performed in the 3D vision analysis room. From the experiment, we obtained result that the center line of body inclined to outside direction during powered-wheelchair rotate any direction.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.47-47
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• 2010

Discharge under the water is very hard and demand considerable high voltage. But specially improved electrode can generate plasma discharge to salty water with relatively low voltage. A round shape ceramic electrode having many pinholes combined with metallic one can generate plasma. 400 volt, 10 kHz and 3 micro second pulse width were applied to repeatedly running synthetic seawater with 10 L/m velocity, containing cultivated E. coli and Bacillus. As a result, 18, 94, 99.97, 100, 100 % disinfection rates to E. coli and 17.1, 17.1, 82.9, 99.4, 99.9 % disinfection rates to Bacillus subtilis were achieved to 1, 2, 3, 4, 5 times repetitive treatment respectively. In the plasma condition, the ions and electrons are separated and new kinds of components are re-synthesized by the intensive movement of the components. Especially chlorine ions are separated and recombined to residual free chlorine like HOCl, $OCl^-$. The residual free chlorine concentrations of discharged water were 0.25, 0.88, 1.39, 1.59, 1.66 mg $Cl_2$/L after 5 times treatment respectively. Another unconfirmed radical and oxidants for example, OH, $H_2O_2$, and $O_3$ can have an effect on microorganism of course.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.2
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• pp.67-71
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• 2012

In this paper, a push-push oscillator at K-band with a double H-shape metamaterial resonator (DHMR) based on high-Q is proposed with metamaterial structure to improve the phase noise and output power. The proposed oscillator shows low phase noise and high output power. DHMR is designed to be high-Q at resonance frequency through strong coupling of E-field. oscillators which are combined in push-push structure improve output power. The propose push-push oscillator shows the output power of 3.1 dBm, the fundamental signal suppression of -23.7 dBc and phase noise of -116.28 dBc at 100 kHz offset frequency and 20.20 GHz center frequency.

• Korean Journal of Materials Research
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• v.15 no.2
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• pp.106-111
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• 2005

Effects of stainless steel-making dusts and binder content on compacting $density(\rho)$ and magnetic properties were evaluated. Cores compacted with the mixture of pure Fe powders, $5wt.\%$ dusts and $0.25wt.\%$ binder showed good AC magnetic properties. For example, permeability$({\mu}a)$ and core loss(P) of the cores containing $5wt.\%$ dusts at 500 kHz were 62 and $4008\;{\mu}W/cm^3$, respectively. These properties are almost equivalent to those of competitor's products (i.e, Ancorsteel TC 80 produced by $H\ddot{o}gan\ddot{a}s$ Corp.). The powdered cores obtained from the present work are expected to apply for high-performance soft magnetic components such as normal mode choke filter and pulse transformer.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.11-18
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• 2013

PURPOSES : This study presents the noise level and frequency characteristics investigated in the national highways with the consideration of various measuring conditions and/or methods. METHODS : The noise levels on the asphalt concrete pavement(ACP) and the jointed plain concrete pavement(JPCP) of the national highway were measured and analysed with respect to three variables, i.e., pavement type, surface condition, and measurement distance. The PASS-By method is utilized for the noise measurement and then using CPB spectrum analysis method with 1/3 octave bandwidth, the noise levels and frequency characteristics were calculated for two-second periods before and after the peak noise. RESULTS : Depending on the pavement type, the noise level was changed as the average noise levels are 73.3dB(A) and 78.3dB(A) for ACP and JPCP, respectively. With respect to the effect of surface condition, the average noise levels for crack H(high), M(medium), and L (low) sections are 77.4dB(A), 77.4dB(A), and 78.1dB(A), respectively. Regarding the measurement distance, 1.2meter difference in measuring location reduces 1.6dB(A) of noise level; the average noise levels at 5.3m and 7.5m from the centerline of outer lane are 72.8dB(A) and 71.2dB(A), respectively. It should be noted that the noise levels are slightly different as a function of vehicle speed and type. However, the overall trends for each case was similar. It was found that the domain frequency bands for ACP and JPCP were 400Hz~2000Hz and 500Hz~2000Hz, respectively. CONCLUSIONS : Based on the analysis with the measured noise date from national highway, it was concluded that the noise level and frequency band vary depending on the various conditions. It was also found that some variables significantly affect the noise level while others do not. With further systematic investigation, the comprehensive noise characteristics on the national highway can be achieved. Using such database, it is possible to develop the fundamental noise reduction technology.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.227-230
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• 2016

Zn_xMn_3-xO₄ (0.95≤x≤1.20) specimens were prepared using a conventional solid state reaction method. All specimens were sintered in air at 1,200℃ for 12 h, cooled at a rate of 2℃/min to 800℃, and subsequently quenched to room temperature. We investigated the electrical properties of Zn_xMn_3-xO₄ specimens with various amounts of ZnO for use as IR detectors. At a composition of x≥1.15, the ZnO phase precipitates beside the spinel structure. The electrical resistivity at room temperature, activation energy, responsivity, and detectivity of a Zn_1.10Mn_1.90O₄ specimen are 653.2 kΩ-cm, 0.392 eV, 0.016 V/W, and 7.52×10³ cmHz^1/2/W, respectively.

• Corrosion Science and Technology
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• v.8 no.2
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• pp.62-67
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• 2009

Ti and Ti-alloys have good biocompatibility, appropriate mechanical properties and excellent corrosion resistance. However, the widely used Ti-6Al-4V is found to release toxic ions (Al and V) into the body, leading to undesirable long-term effects. Ti-6Al-4V has much higher elastic modulus (100 GPa) than cortical bone (20 GPa). Therefore, titanium alloys with low elastic modulus have been developed as biomaterials to minimize stress shielding. The electrochemical behavior of surface-modified and MC3T3-E1 cell-cultured Ti-30(Nb,Ta) alloys with low elastic modulus have been investigated using various electrochemical methods. Surfaces of test samples were treated as follows: $0.3{\mu}m$ polished; $25{\mu}m$, $50{\mu}m$ and $125{\mu}m$ sandblasted. Specimen surfaces were cultured with MC3T3-E1 cells for 2 days. Average surface roughness ($R_a$) and morphology of specimens were determined using a surface profilometer, OM, and FE-SEM. Corrosion behavior was investigated using a potentiostat(EG&G PARSTAT 2273), and electrochemical impedance spectroscopy was performed (10 mHz to 100 kHz) in 0.9% NaCl solution at $36.5{\pm}1^{\circ}C$. The microstructures of the Ti-30(Ta,Nb) alloys had a needle-like appearance. The $R_a$ of polished Ti-30Ta and Ti-30Nb alloys was lower than that of the sandblasted Ti alloy. Cultured cells displayed round shapes. For polished alloy samples, cells were well-cultured on all surfaces compared to sandblasted alloy samples. In sandblasted and cell-cultured Ti-30(Nb,Ta) alloy, the pitting potential decreased and passive current density increased as $R_a$ increased. Anodic polarization curves of cell-cultured Ti alloys showed unstable behavior in the passive region compared to non-cell-cultured alloys. From impedance tests of sandblasted and cell-cultured alloys, the polarization resistance decreased as $R_a$ increased, whereas, $R_a$ for cell-cultured Ti alloys increased compared to non-cell-cultured Ti alloys.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.16-19
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• 2000

DC and low frequency noise characteristics of InGaP/InGaAs pseudomorphic HEMTs (p-HEMTs) grown by compound source MBE are investigated for temperature range of 150K to 370K. Equivalent input noise spectra( $S_{iv}$ ) were measured as a function of frequency and temperature. $S_{iv}$ was measured to be 3.4 $\times$ 10$^{-12}$ $V^2$/ Hz at 1kHz for 1.3 X 50${\mu}{\textrm}{m}$$^2$InGaP/InGaAs p-HEMT at room temperature. Measurements of the low-frequency noise spectra of the p-HEMT as a function of temperature show that the trap with an activation energy level around 0.589 eV is a dominant trap that accounts for the low-frequency noise behavior of the device. The normalized extrinsic gm frequency dispersion of the p-HEMT. was as low as 2.5％ at room temperature, indicating that the device has well-behaved low-frequency noise characteristics. Sub-micron (0.25 $\times$ 50${\mu}{\textrm}{m}$$^2$) gate p-HEMT showed $f_{T}$ and $f_{max}$ of 40GHz and 108GHz, respectively.y.y.