• Journal of the Korean Ceramic Society
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• v.54 no.3
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• pp.222-227
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• 2017

Flake-type micro hollow silica was synthesized by precipitation method using an $Mg(OH)_2$ inorganic template and sodium silicate and ammonium sulfate as the silica precursors. We investigated the effects of the silica precursor concentration on the shape, shell thickness, and surface of the hollow silica. When the concentration of the silica precursor was 0.5 M, the hollow silica had a smooth and translucent thin shell, but the shell was broken. On the other hand, the shell thickness of the hollow silica changed in the range of 12 nm to 18 nm with the increase of the precursor concentration from 0.7 M to 1.1 M. Simultaneously, unintended spherical silica satellites were created on the shell surface. The number of satellites and the size rose according to the increased concentration of silica precursor. The reason for the formation of spherical silica satellites is that the $NH_4OH$ nucleus generated in the synthesis of hollow silica acted as another silica reaction site.

• Journal of Biosystems Engineering
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• v.30 no.3 s.110
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• pp.147-154
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• 2005

The improved hitch device, which connecting the trailer to power tiller, was developed. This device, composed with spring and rubber, could reduce the vibration and shock levels during driven on off-road. The vertical vibration accelerations for the improved hitch device were measured at 6 positions, i.e. engine, hitch, seat, and three points in trailer (front, middle, and rear) for not driving but at low engine speed of 500 rpm, and compared with the existing hitch device. The results of this study could be summarized as follows; The average vibration acceleration up to 120 Hz was $0.4m/s^2$ at engine part, but it was 0.08 and $0.05m/s^2$ at trailer for existing and improved hitch device, respectively. About $38\%$ of average acceleration level could be absorbed for the improved hitch device compared with existing hitch device. The average vibration acceleration up to 40 Hz was reduced to 0.12 and $0.06m/s^2$ at trailer for existing and improved hitch device respectively, showing the reduction effect of $50\%$. The maximum acceleration occurred at up to 20 Hz of low frequency was much higher than total acceleration occurred at up to 120 Hz, which means that much loss or damage could be occurred during transporting of agricultural products on off-road. The portions of average acceleration occurred at up to 20 Hz of low frequency were $27\%\;and\;21\%$ for the existing and improved hitch device, respectively.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.4
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• pp.40-50
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• 1993

In this paper, MODFET devices with various gate length are simulated using the Monte-Carlo method. The number of superparticle is 5000 and the Poisson equation is solved to obtain field distribution. The structure of MODFET is n-AlGaAs/i-AlGaAs/iGaAs and doping concentration of n-AlGaAs layer is 1${\times}10^{17}/cm^{3}$ and the thickness is 500.angs., and the thickness of i-AlGaAs is 50$\AA$. The devices with gate length 0.2$\mu$m, 0.5$\mu$m, 1.0$\mu$m respctively are simulated and the current-voltage curves and transport characteristics of that devices are obtained. Occupancy of each subband and electron energy distribution and conduction energy band in channel have been analyzed to obtain transport characteristics, and particles transposed from source to drain have been analyzed to current-voltage curves. Current level is highest for the device of Lg=0.2$\mu$m and transconductance of this device is 310mS/mm.

• Journal of Biomedical Engineering Research
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• v.34 no.2
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• pp.69-72
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• 2013

The goal of this study is to develop test method for evaluating the drug eluting properties of drug eluting stents (DES). PBS and the detergent solutions, presented by each DES manufacturer, were used for drug release of DES coated with paclitaxel, zotarolimus and everolimus. The drugs which are coating DES were not released by PBS but released by the detergent solutions, finally paclitaxel 83.38%, zotarolimus 103.85% and everolimus 115.78%. It seems that the use of the detergents is necessary in order to release the drugs because those drugs are extremely hydrophobic. In conclusion, using of detergent solutions presented by each manufacturer were suitable for evaluating the drug eluting property of drug eluting stent.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.170-173
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• 2000

In this study, we have investigated the light-emitting property of the EL device with the thickness ratio of the HTL/ETL, which was 500$\AA$:500$\AA$, 400$\AA$:600$\AA$, 600$\AA$:400$\AA$. The ALq$_3$ was used for the ETL. We have studied the relation of voltage, contrase, efficiency for current density. Emission was observed above 10mA/$\textrm{cm}^2$ and luminance was measured to be 1030cd/$m^2$ at a current density of 100mA/$\textrm{cm}^2$ in 500$\AA$/500$\AA$ sample. A luminance of over 2500cd/$m^2$ was also observed after the final fabrication process in 500$\AA$/500$\AA$ sample

• IEIE Transactions on Smart Processing and Computing
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• v.2 no.2
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• pp.67-76
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• 2013

Under an imperfect channel estimation, a Device-to-Device (D2D) communication framework based on MIMO relay technology is presented. The model consists of a D2D pair equipped with M antennas and a relay equipped with N antennas as well as a cellular user equipped with M antennas. The outage probability under different relaying protocols (i.e. AF and DF protocol) with and without considering a direct link was derived. The actual and theoretical outage probability of the five links under different antenna numbers was emulated. The number of user antennas and channel estimation error was analyzed carefully to determine their impact on the outage probability of a system. The simulation verified the theory analyses and the results showed that MIMO relaying improves the D2D communication system performance.

• Journal of Korea Multimedia Society
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• v.17 no.5
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• pp.640-653
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• 2014

Recently medical consumers pursue high leveled quality of life through active promotion, prevention, management activity of health as the importance of health during home life is emerged to meet the aging society and chronic diseases. In addition, people are directed to the m-Health for managing yourself their health by using smartphone and various personal health devices, if necessary transmits health data to the physician himself. In the previous studies, m-Health Application were developed and applied in the real clinical environment by adopting the medical information standards was rarely conducted. Therefore, in this study, the m-Health application platform was developed. Developed application was communicate with IEEE 11073 standard protocol using the Bluetooth Health Device Profile in personal health device via smart phone to process blood pressure information, and it converted to HL7 V2.6 ORU_R01 message for send to remote medical server. In addition, we tested the interoperability and safety of the developed application for 23 inpatient and 17 outpatient at D University Hospital. As a result, the blood pressure information has been transmitted without error.

• Korean Journal of Materials Research
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• v.22 no.9
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• pp.450-453
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• 2012

In crystalline solar cells, the substrate itself constitutes a large portion of the fabrication cost as it is derived from semiconductor ingots grown in costly high temperature processes. Thinner wafer substrates allow some cost saving as more wafers can be sliced from a given ingot, although technological limitations in slicing or sawing of wafers off an ingot, as well as the physical strength of the sliced wafers, put a lower limit on the substrate thickness. Complementary to these economical and techno-physical points of view, a device operation point of view of the substrate thickness would be useful. With this in mind, BC-BJ Si and GaAs solar cells are compared one to one by means of the Medici device simulation, with a particular emphasis on the substrate thickness. Under ideal conditions of 0.6 ${\mu}m$ photons entering the 10 ${\mu}m$-wide BC-BJ solar cells at the normal incident angle (${\theta}=90^{\circ}$), GaAs is about 2.3 times more efficient than Si in terms of peak cell power output: 42.3 $mW{\cdot}cm^{-2}$ vs. 18.2 $mW{\cdot}cm^{-2}$. This strong performance of GaAs, though only under ideal conditions, gives a strong indication that this material could stand competitively against Si, despite its known high material and process costs. Within the limitation of the minority carrier recombination lifetime value of $5{\times}10^{-5}$ sec used in the device simulation, the solar cell power is known to be only weakly dependent on the substrate thickness, particularly under about 100 ${\mu}m$, for both Si and GaAs. Though the optimum substrate thickness is about 100 ${\mu}m$ or less, the reduction in the power output is less than 10% from the peak values even when the substrate thickness is increased to 190 ${\mu}m$. Thus, for crystalline Si and GaAs with a relatively long recombination lifetime, extra efforts to be spent on thinning the substrate should be weighed against the expected actual gain in the solar cell output power.

• Journal of Magnetics
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• v.13 no.1
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• pp.30-33
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• 2008

A highly sensitive, giant magnetoresistance-spin valve (GMR-SV) biosensing device with high linearity and very low hysteresis was fabricated by photolithography. The detection of magnetic nanoparticles and Fe-hemoglobin inside red blood cells using the GMR-SV biosensing device was investigated. When a sensing current of 1 mA was applied to the current electrode in the patterned active devices with an area of $2{\times}6{\mu}m^2$, the output signals were about 13.35 mV. The signal from even one drop of human blood and nanoparticles in distilled water was sufficient for their detection and analysis.

• Journal of Digital Convergence
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• v.11 no.2
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• pp.309-316
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• 2013

Machine-to-machine (M2M) communication occurs when devices exchange information independent of human intervention. Prominent among the technical challenges to M2M communication are security issues, such as eavesdropping, spoofing, modification, and privacy violation. Hence, it is very important to establish secure communication. In this paper, we propose a remote authentication scheme, based on dynamic ID, which provides secure communication while avoiding exposure of data through authentication between the M2M domain and the network domain in the M2M architecture. We then prove the correctness and security of the proposed scheme using a logic-based formal method.