• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.599-607
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• 1986

Acute toxicity of crude oil (WSF) on the mortality and respiration rates of Neomysis awatschensis was examined. This experiment was conducted by static and short-term bioassay procedure. In lethal test, the test animals were exposured to 8 different concentrations to determine $LC_{50}$ value (median lethal concentration). The concentrations of total hydrocarbon of 96-hr $LC_{50}$ value at $14^{\circ}C\;and\;20^{\circ}C$ were 1.01 ppm and 0.78 ppm, respectively. $LT_{50}$ (the median lethal time) also was determined. The $LT_{50}$ of 0.56 ppm was found within 100 hours, while the $LT_{50}$ of 5.6 ppm was 21 hours at $14^{\circ}C$. At $20^{\circ}C$, the $LT_{50}$ values of 0.56 ppm and 5.60 ppm were 95 hours and 17 hours, respectively. There was little difference between two temperature experiments. The effect of WSF on respiration rate was more sensitive than that on mortality, but no considerable difference was shown between different concentrations in this experiment. The results of these experiments indicated that relatively low concentration of dissolved crude oil fraction can impact on small crustacean in the marine ecosystem.

• Journal of the Korean Ceramic Society
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• v.43 no.12 s.295
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• pp.812-822
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• 2006

This study amis to investigate the functional analysis of anode and cathode materials in Anode supported Solid Oxide Fuel Cell. The concentration polarization of single cell was investigated with CFD (Computational Fluid Dynamics) method for the case of the different morphology by using four types of unit cell and discussed to reduce the concentration polarization. The concentration polarization at anode side effected the voltage loss in Anode supported Solid Oxide Fuel Cell and increased contact areas between fuel gas and anode side could reduce the concentration polarization. For intermediate temperature operation, Anode-supported single cells with thin electrolyte layer of YSZ (Yttria-Stabilized Zirconia) were fabricated and short stacks were built and evaluated. We also developed diesel and methane autothermal reforming (ATR) reactors in order to provide fuels to SOFC stacks. Influences of the $H_2O/C$ (steam to carbon ratio), $O_2/C$ (oxygen to carbon ratio) and GHSV (Gas Hourly Space Velocity) on performances of stacks have been investigated. Performance of the stack operated with a diesel reformer was lower than with using hydrogen as a fuel due to lower Nernst voltage and carbon formation at anode side. The stack operated with a natural gas reformer showed similar performances as with using hydrogen. Effects of various reformer parameters such as $H_2O/C$ and $O_2/C$ were carefully investigated. It is found that $O_2/C$ is a sensitive parameter to control stack performance.

• Journal of the Korean Magnetics Society
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• v.21 no.2
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• pp.77-82
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• 2011

The use of soft magnetic materials have been increasing in the various industrial fields according to the increasing demand for high performance, automatic, miniaturing equipments in the recent our life. In this study, we investigated the effect of factors on the core loss and magnetic properties of electrical steel and soft magnetic composites. Furthermore, we reviewed the major efforts to reduce the core loss and improve the soft magnetic properties in the two main soft magnetic materials. Domain purification which results from reduced density of defects in cleaner electrical steels is combined with large grains to reduce hysteresis loss. The reduced thickness and the high electrical conductivity reduce the eddy current component of loss. Furthermore, the coating applied to the surface of electrical steel and texture control lead to improve high permeability and low core loss. There is an increasing interest in soft magnetic composite materials because of the demand for miniaturization of cores for power electronic applications. The SMC materials have a broad range of potential applications due to the possibility of true 3-D electromagnetic design and higher frequency operation. Grain size, sintering temperature, and the degree of porosity need to be carefully controlled in order to optimize structure-sensitive properties such as maximum permeability and low coercive force. The insulating coating on the powder particles in SMCs eliminates particle-to-particle eddy current paths hence minimizing eddy current losses, but it reduces the permeability and to a small extent the saturation magnetization. The combination of new chemical composition with optimum powder manufacturing processes will be able to result in improving the magnetic properties in soft magnetic composite materials, too.

• Journal of Life Science
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• v.20 no.5
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• pp.683-690
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• 2010

The yeast strains of Saccharomyces diastaticus produce one of three isozymes of an extracellular glucoamylase I, II or III, a type of exo-enzyme which can hydrolyse starch to generate glucose molecules from non-reducing ends. These enzymes are encoded by the STA1, STA2 and STA3 genes. Another gene, sporulation-specific glucoamylase (SGA), also exists in the genus Saccharomyces which is very homologous to the STA genes. The SGA has been known to be produced in the cytosol during sporulation. However, we hypothesized that the SGA is capable of being secreted to the extracellular region because of about 20 hydrophobic amino acid residues at the N-terminus which can function as a signal peptide. We expressed the cloned SGA gene in S. diastaticus YIY345. In order to compare the biochemical properties of the extracellular glucoamylase and the SGA, the SGA was purified from the culture supernatant through ammonium sulfate precipitation, DEAE-Sephadex A-50, CM-Sephadex C-50 and Sephadex G-200 chromatography. The molecular weight of the intact SGA was estimated to be about 130 kDa by gel filtration chromatography with high performance liquid chromatography (HPLC) column. Sodium dedecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed it was composed of two heterogeneous subunits, 63 kDa and 68 kDa. The deglycosylation of the SGA generated a new 59 kDa band on the SDS-PAGE analysis, indicating that two subunits are glycosylated but the extent of glycosylation is different between them. The optimum pH and temperature of the SGA were 5.5 and $45^{\circ}C$, respectively, whereas those for the extracellular glucoamylase were 5.0 and $50^{\circ}C$. The SGA were more sensitive to heat and SDS than the extracellular glucoamylase.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.357-363
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• 2008

This study investigates the durability of carbon/epoxy composites for use on train car bodies under a salt water spray environment. Salt water solution with 5% NaCl, similar to natural salt water, was used for the salt water environmental tests. The specimens were obtained from a composite panel consisting of an epoxy matrix reinforced with T700 carbon fabric. The specimens were exposed to the salt water environment for up to 12 months. Mechanical tests were performed to obtain tensile properties, flexural properties, and shear properties. Dynamic mechanical analysis was used to measure such thermal properties as storage modulus, loss modulus, and tan $\delta$. Also FT/IR tests were conducted to investigate changes in chemical structure with exposure. The results revealed that fiber-dominated mechanical properties were not affected much by exposure time, but matrix-dominated mechanical properties decreased with increasing exposure time. Storage modulus was not very sensitive to exposure time, but glass transition temperature was affected, slightly decreasing with increasing exposure time. Although the peak intensity of FT/IR curves was affected slightly by exposure time, the peak shape and peak location of FT/IR curves were not noticeably changed. Carbon/epoxy composites used for this study were relatively stable to the salt water environment.

• Korean Journal of Microbiology
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• v.44 no.4
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• pp.293-298
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• 2008

HCV is transmitted via various plasma derived products. Current methods to detect hepatitis C virus (HCV) are based on its antibody detection in the donated blood and plasma. Viral contamination can potentially escape such detection during the window period of infection, when no antibody is present or the level of antibody is too low to detect. It is trying to application of nucleic acid amplification tests (NAT) for the direct detection of HCV. The objective of this study was to develop a reliable NAT for the HCV RNA detection from plasma-derived products. The most useful primers was selected for NAT among 5 sets of primers. We have also found that QIAamp viral RNA isolation kit was the most efficient for HCV RNA isolation. The highest sensitivity and specificity was appeared in $48^{\circ}C$ annealing temperature and 30 pmol of primers. With a spiking of HCV to albumin, immunoglobulins and coagulation factors, NAT can detect up to 100 IU/ml. Meanwhile, COBAS amplicor HCV 2.0 afforded a lower sensitivity in high concentrated intramuscular immunoglobulins to below 500 IU/ml. Our results suggested that NAT appears to be a highly sensitive and specific method for HCV RNA detection in plasma-derived products.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.1
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• pp.13-19
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• 2009

A 440MHz wireless and passive surface acoustic wave (SAW) based chemical sensor was developed on a $41^{\circ}YX\;LiNbO_3$ piezoelectric substrate for simultaneous measurement of $CO_2$ gas and relative humidity (RH) using a reflective delay line pattern as the sensor element. The reflective delay line is composed of an interdigital transducer (IDT) and several shorted grating reflectors. A Teflon AF 2400 and a hydrophilic $SiO_2$ layer were used as $CO_2$ and water vapor sensitive films. The coupling of mode (COM) modeling was conducted to determine optimal device parameters prior to fabrication. According to simulation results, the device was fabricated and then wirelessly measured using the network analyzer. The measured reflective coefficient $S_{11}$ in the time domain showed high signal/noise (S/N) ratio, small signal attenuation, and few spurious peaks. In the $CO_2$ and humidity testing, high sensitivity ($2^{\circ}/ppm$ for $CO_2$ detection and $7.45^{\circ}/%$RH for humidity sensing), good linearity and repeatability were observed in the $CO_2$ concentration ranges of $75{\sim}375ppm$ and humidity levels of $20{\sim}80%$RH. Temperature and humidity compensations were also investigated during the sensitivity evaluation process.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1775-1781
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• 2008

The effects of the type of curing agent on the swelling of the natural rubber(NR) sponge applicable to the self-sealing layer of a helicopter fuel tank were investigated. The curing systems employed were peroxide and mixed ones of sulfur and peroxide. The NR compounds were prepared in a kneader and a roll-mill. The compounds were partially cured in a press at high pressure and subsequently cured fully with expansion in another press at atmospheric pressure. The apparent density of the NR sponge was measured and the cell structure was observed with scanning electron microscopy. The swelling experiments were performed at room temperature using toluene, iso-octane, and an aircraft fuel as a solvent. More rapid volume swelling of the NR sponge cured by peroxide was achieved than cured by sulfur and peroxide with similar amount of curing agent added in rubber compounds. The apparent density and cell structure of the sponge were extremely sensitive to the amount of peroxide, which influences again the swelling behavior of the NR sponge. It is important to control properly two reactions of decomposition of foaming agent and crosslinking of NR in the mold to obtain rapid swelling of the NR sponge on contact of the fuel.

• Journal of Sensor Science and Technology
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• v.8 no.3
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• pp.239-246
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• 1999

A highly sensitive photovoltaic infrared photodiode was fabricated for detecting infrared light in $3{\sim}5\;{\mu}m$ wavelength range on InSb wafer with p-i-n structure grown by MOCVD. Silicon dioxide($SiO_2$) insulating films for the junction interface and surface of photodiode were prepared using RPCVD because InSb has low melting point and evaporation temperature. After formation of In ohmic contacts by thermal evaporation, the electrical properties of the photodiode were characterized in dark state at 77K. A product of zero-bias resistance and area($R_0A$) showed $1.56{\times}10^6\;{\Omega}{\cdot}cm^2$ that satisfied BLIP(background limited infrared photodetector) condition. When the photodiode was tested under infrared light, the normalized detectivity of about $10^{11}\;cm{\cdot}Hz^{1/2}{\cdot}W^{-1}$ was obtained. we successfully fabricated a unit cell with InSb IR array with good quantum efficiency and high detectivity.

• Weed & Turfgrass Science
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• v.3 no.3
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• pp.225-231
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• 2014

Benzobicyclon induces phytotoxicity to Tongil type rice, although it is an efficient herbicide in paddy. This study was performed to figure out the benzobicyclon-induced phytotoxicity responses of whole crop forage rice genotypes that have the genetic background similar to Tongil type rice, under wet-seeded and transplanted conditions. Mogwoo demonstrated whitening symptom at all the temperatures in both wet-seeding and transplanting by the application of standard and double rates of benzobicyclon. Nokyang, Mogyang and Suweon560 exhibited no or negligible whitening and their plant heights were not reduced at standard rate of benzobicyclon. But in double rate application in wet-seeding, the three genotypes showed 0-8% of white plants at all temperature treatments and reduction in plant height was comparatively larger at $27^{\circ}C$. In transplanting, the double rate application of benzobicyclon at 24 and $27^{\circ}C$ induced 0-32% of whitening plants depending on genotypes while no whitening plants were observed at 18 and $21^{\circ}C$ in all genotypes. Reduction in biomass by double rate of benzobicyclon at 24 and $27^{\circ}C$ was greater than at 18 and $21^{\circ}C$. It is concluded that Mogwoo is extremely sensitive to benzobicyclon and Nokyang, Mogyang and Suweon560 are tolerant to the standard rate of benzobicyclon.