• Korean Journal of Food Science and Technology
• /
• v.31 no.2
• /
• pp.410-415
• /
• 1999

Yakju was sterilized with high-voltage pulses of short time of a continuous pulsed electric field (PEF) system. The initial microbial counts of Yakju were $2.2{\times}10^{5}$ CFU/mL for total aerobes. The pH, acidity and electric conductivity of Yakju were 3.82, 0.37% and 1.24 mS/cm, respectively. Yakju was treated with exponential-wave formed electric pulses of 100 Hz for $0{\sim}4000{\mu}s$ under the field strength of $20{\sim}35\;kV/cm$. The lethal effect of electric fields on microorganisms was resulted from the breakdown of the cell membrane induced by the transmembrane electric potential. The critical values of the external field for the sterilization were 16.0 kV/cm for total aerobes. Logarithmic survival rates decreased linearly at low electric field strength, but curvilinearly at high electric field strength with treatment time. The sterilization of Yakju was more largely affected by the electric field strength than by the treatment time. Any changes in pH, acidity, and the growth of microorganisms were not found in the PEF treated Yakju during the storage at both $4^{\circ}C\;and\;30^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.29 no.8
• /
• pp.461-465
• /
• 2016

n-type silicon shows the better tolerance towards metal impurities with a higher minority carrier lifetime compared to p-type silicon substrate. Due to better lifetime stability as compared to p-type during illumination made the photovoltaic community to switch toward n-type wafers for high efficiency silicon solar cells. We fabricated the front electrode of the n-type solar cell with AgAl paste. The electrodes characteristics of the AgAl paste depend on the contact junction depth that is closely related to the firing temperature. Metal contact depth with p+ emitter, with optimized depth is important as it influence the resistance. In this study, we optimize the firing condition for the effective formation of the metal depth by varying the firing condition. The firing was carried out at temperatures below $670^{\circ}C$ with low contact depth and high contact resistance. It was noted that the contact resistance was reduced with the increase of firing temperature. The contact resistance of $5.99m{\Omega}cm^2$ was shown for the optimum firing temperature of $865^{\circ}C$. Over $900^{\circ}C$, contact junction is bonded to the Si through the emitter, resulting the contact resistance to shunt. we obtained photovoltaic parameter such as fill factor of 76.68%, short-circuit current of $40.2mA/cm^2$, open-circuit voltage of 620 mV and convert efficiency of 19.11%.

• Journal of the Korean Magnetics Society
• /
• v.24 no.4
• /
• pp.123-127
• /
• 2014

We developed a digital 3-axis flux-gate magnetometer for magnetic field signal measurement from warship during demagnetizing and degaussing processes. For the magnetometer design, we considered following points; the distance between magnetic field measurement station and magnetometer located under sea is about several 100 m, the magnetometer is exposed to magnetic field of ${\pm}1mT$ during demagnetizing process, and magnetometer is located under the sea about 30 m depth. To overcome long distance problem, magnetometer could be operated on wide input supply voltage range of 16~36 V using DC/DC converter, and for the data communication between the magnetometer and measurement station a RS422 serial interface was employed. To improve perming effect due to the ${\pm}1mT$ during demagnetizing process, magnetometer could be compensated external magnetic field up to ${\pm}1mT$ but magnetic field measuring rang is only ${\pm}100{\mu}T$. The perming effect was about ${\pm}2nT$ under ${\pm}1mT$ external magnetic field. The magnetometer was tested water vessel with air pressure up to 6 bar for the sea water pressure problems. Linearity of the magnetometer was better than 0.01 % in the measuring range of ${\pm}0.1mT$ and noise level was $30pT/\sqrt{Hz}$ at 1 Hz.

• Korean Journal of Optics and Photonics
• /
• v.15 no.5
• /
• pp.469-474
• /
• 2004

We have fabricated and designed wavelength-tunable sampled grating distributed Bragg reflector laser diodes(SGDBR-LD) by using, for the first time, planar buried heterostructures(PBH). The diodes have low threshold current values and high-performance of laser operation. Growth condition using metal organic chemical vapor deposition(MOCVD) was optimized for the formation of a good butt-coupling at the interface. A maximum output power of the fabricated device was 20 mW under 200 mA continuous wave(CW) operation at $25^{\circ}C$. Average threshold current and voltage were 12 mA and 0.8 V, approximately. This output power is higher than those of ridge waveguide(RWG) and buried ridge stripe(BRS) structures by amounts of 9 mW and 13 mW, respectively. We obtained a tuning range of 44.4nm which is well matched with the target value of our design. The side mode suppression ratio of more than 35 dB was obtained for the whole tuning range. Optical output power variation was less than 5 dB, which is 4 dB smaller than that of RWG structures.

• Journal of the Korean Solar Energy Society
• /
• v.32 no.4
• /
• pp.24-33
• /
• 2012

Recently, finishing materials at spandrel area, a part of curtain-wall system, are gradually forced to improve thermal insulation performance in order to enhance the building energy efficiency. Also, Building Integrated Photovoltaics(BIPV) systems have been installed in the exterior side of the spandrel area, which is generally composed of windows. Those BIPVs aim to achieve high building energy efficiency and supply the electricity to building. However, if transparent BIPV module is combined with high insulated spandrel, it would reduce the PV efficiency for two major reasons. First, temperature in the air space, located between window layer and finishing layer of the spandrel area, can significantly increase by solar heat gain, because the space has a few air density relative to other spaces in building. Secondly, PV has a characteristics of decreased Voltage(Voc and Vmp) with the increased temperature on the PV cell. For these reasons, this research analyzed a direct interrelation between PV Cell temperature and electricity generation performance under different insulation conditions in the spandrel area. The different insulation conditions under consideration are 1) high insulated spandrel(HIS) 2) low insulated spandrel(LIS) 3) PV stand alone on the ground(SAG). As a result, in case of 1) HIS, PV temperature was increased and thus electricity generation efficiency was decreased more than other cases. To be specific, each cases' maximum temperature indicated that 1) HIS is $83.8^{\circ}C$, 2) LIS is $74.2^{\circ}C$, and 3) SAG is $66.3^{\circ}C$. Also, each cases yield electricity generation like that 1) HIS is 913.3kWh/kWp, 2) LIS is 942.8kWh/kWp, and 3) SAG is 981.3kWh/kWp. These result showed that it is needed for us to seek to the way how the PV Cell temperature would be decreased.

• Korean Journal of Materials Research
• /
• v.10 no.12
• /
• pp.812-818
• /
• 2000

We studied the effects of Ge preamorphization (PAM) on 0.25$\mu\textrm{m}$ Ti-salicide junctions using comparative study with As PAM. For each PAM schemes, ion implantations are performed at a dose of 2E14 ion/$\textrm{cm}^2$ and at 20keV energy using $^{75}$ /As+and GeF4 ion sources. Ge PAM showed better sheet resistance and within- wafer uniformity than those of As PAM at 0.257m line width of n +/p-well junctions. This attributes to enhanced C54-silicidation reaction and strong (040) preferred orientation of the C54-silicide due to minimized As presence at n+ junctions. At p+ junctions, comparable performance was obtained in Rs reduction at fine lines from both As and Ge PAM schemes. Junction leakage current (JLC) revels are below ~1E-14 A/$\mu\textrm{m}^{2}$ at area patterns for all process conditions, whereas no degradation in JLC is shown under Ge PAM condition even at edge- intensive patterns. Smooth $TiSi_2$ interface is observed by cross- section TEM (X- TEM), which supports minimized silicide agglomeration due to Ge PAM and low level of JLC. Both junction break- down voltage (JBV) and contact resistances are satisfactory at all process conditions.

• Polymer(Korea)
• /
• v.33 no.3
• /
• pp.191-197
• /
• 2009

We have investigated the effect of strong p-type organic semiconductor $F_4$-TCNQ-doped CuPc hole transport layer on the performance of p-i-n type bulk heterojunction photovoltaic device with ITO/PEDOT:PSS/CuPc: $F_4$-TCNQ(5 wt%)/CuPc:C60(blending ratio l:l)/C60/BCP/LiF/Al, architecture fabricated via vacuum deposition process, and have evaluated the J-V characteristics, short-circuit current ($J_{sc}$), open-circuit voltage($V_{oc}$), fill factor(FF), and power conversion efficiency(${\eta}_e$) of the device. By doping $F_4$-TCNQ into CuPc hole transport layer, increased absorption intensity in absorption spectra, uniform dispersion of organic molecules in the layer, surface uniformity of the layer, and enhanced injection currents improved the current photovoltaic device with power conversion efficiency(${\eta}_e$) of 0.16%, which is still low value compared to silicone solar cell indicating that many efforts should be made to improve organic photovoltaic devices.

• Journal of the Korean Magnetics Society
• /
• v.16 no.3
• /
• pp.157-162
• /
• 2006

In this study, a high sensitive giant magnetoresistance-spin valve (GMR-SV) bio-sensing device with high linearity and very low hysteresis was fabricated by photolithography and ion beam deposition sputtering system. Detection of the Fe-hemoglobin inside in a red blood and magnetic nanoparticles using the GMR-SV bio-sensing device was investigated. Here a human's red blood includes hemoglobin, and the nanoparticles are the Co-ferrite magnetic particles coated with a shell of amorphous silica which the average size of the water-soluble bare cobalt nanoparticles was about 9 nm with total size of about 50 nm. When 1 mA sensing current was applied to the current electrode in the patterned active GMR-SV devices with areas of $5x10{\mu}m^2 $ and $2x6{\mu}m^2 $, the output signals of the GMRSV sensor were about 100 mV and 14 mV, respectively. In addition, the maximum sensitivity of the fabricated GMR-SV sensor was about $0.1{\sim}0.8%/Oe$. The magnitude of output voltage signals was obtained from four-probe magnetoresistive measured system, and the picture of real-time motion images was monitored by an optical microscope. Even one drop of human blood and nanopartices in distilled water were found to be enough for detecting and analyzing their signals clearly.

• Journal of the Korean institute of surface engineering
• /
• v.39 no.3
• /
• pp.93-97
• /
• 2006

Polymer light emitting diodes (PLEDs) are expected to be commercialized as next generation displays by advantages of the fast response time, low driving voltage and easy manufacturing process for large sized flexible display. Generally, the electrical and optical properties of PLEDs are affected by the surface conditions of transparent electrode. The PLED devices with ITO/PEDOT:PSS/PVK/PFO-poss/LiF/Al structures were prepared by using the spin coating method. For this, PEDOT:PSS(poly(3,4-ethylenedioxythiophene):poly(styrene sulfolnate)) Al 4083 and PVK(N-vinylcabozole) were used as hole injection and transport layers. The PFO-poss(poly(9,9-dioctylfluorene)) was used as the emitting layer. The dependence of $O_2$ plasma treatment of ITO electrode on the electrical and optical properties of PLEDs were investigated. The sheet resistances increased slightly with an improved surface roughness of ITO electrode as the RF power increased during $O_2$ plasma treatment. The PLED devices prepared on the ITO/Glass substrates, which were plasma-treated at 40 watt in RF power for 30 seconds under 40 mtorr $O_2$ pressure, showed the maximum external emission efficiency of 0.86 lm/W and the maximum luminance of $250\;cd/m^2$, respectively. The CIE color coordinates are ranged $X\;=\;0.13{\sim}0.18$ and $Y\;=\;0.10{\sim}0.16$, showing blue color. emission.

• The Korean Journal of Physiology and Pharmacology
• /
• v.3 no.1
• /
• pp.101-117
• /
• 1999

Amyotrophic lateral sclerosis (ALS) is a degenerative neuromuscular disease of unknown etiology in which the upper and lower motor neurons are progressively destroyed. Recent evidences support the role of autoimmune mechanisms in the pathogenesis of ALS. This study investigated the effects of sera from ALS patients on neuromuscular transmission in phrenic nerve-hemidiaphragm preparations and on calcium currents of single isolated dorsal root ganglion (DRG) cells in mice. Mice were injected with either control sera from healthy adults or ALS sera from 18 patients with ALS of sporadic form, for three days. Miniature end plate potential (MEPP) and nerve-evoked end plate potential (EPP) were measured using intracellular recording technique and the quantal content was determined. Single isolated DRG cells were voltage-clamped with the whole-cell configuration and membrane currents were recorded. Sera from 14 of 18 ALS patients caused a significant increase in MEPP frequency in normal Ringer's solution $(4.62{\pm}0.14\;Hz)$ compared with the control $(2.18{\pm}0.15\;Hz).$ In a high $Mg^{2+}/low\;Ca^{2+}$ solution, sera from 13 of 18 ALS patients caused a significant increase in MEPP frequency, from $2.18{\pm}0.31$ Hz to $6.09{\pm}0.38$ Hz. Sera from 11 of 18 patients produced a significant increase of nerve-evoked EPP amplitude, from $0.92{\pm}0.05$ mV to $1.30{\pm}0.04$ mV, while the other seven ALS sera did not alter EPP amplitude. In the ALS group, EPP quantal content was also elevated by the sera of 14 patients (from $1.49{\pm}0.07$ to $2.35{\pm}0.07).$ MEPP frequency and amplitude in wobbler mouse were $4.03{\pm}0.53$ Hz and $1.37{\pm}0.18$ mV, respectively, which were significantly higher than those of wobbler controls (wobblers without the symptoms of wobbler). Sera from ALS patients significantly reduced HVA calcium currents of DRG cells to 42.7% at -10 mV. Furthermore, the inactivation curve shifted to more negative potentials with its half-inactivation potential changed by 6.98 mV. There were, however, significant changes neither in the reversal potential of $I_{Ca}$ nor in the I-V curve. From these results it was concluded that: 1) The serum factors of sporadic ALS patients increase neuromuscular transmission and can alter motor nerve terminal presynaptic function. This suggests that ALS serum factors may play an important role in the early stage of ALS, and 2) Calcium currents in DRG cells were reduced and rapidly inactivated by ALS sera, suggesting that in these cells, ALS serum factors may exert interaction with the calcium channel.