• Korean Journal of Agricultural Science
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• v.35 no.1
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• pp.1-9
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• 2008

There were four types of Doenjang fermentation as following conditions for investigation ; 1) low temperature fermentation at $13^{\circ}C$ for 180 days, 2) low temperature at $13^{\circ}C$ for 7 days to room temperature at $30^{\circ}C$ for 10 days, to low temperature at $13^{\circ}C$ for 163 days, and for 173 days, 3) low temperature at $13^{\circ}C$ 7 days to room temperature at $30^{\circ}C$, 4) room temperature at $30^{\circ}C$ for 180 days. There were no changes of moisture, NaCl and total nitrogen content during fermentation period of four types conditions, but pH and amino type nitrogen decreased in room temperature at $30^{\circ}C$ for 180 days. It required 3 times more fermentation period until same quantity of the amino type nitrogen. The low temperature fermentation sample was lower than room temperature fermentation sample in pH and amino type nitrogen. The yeast decreased in low temperature fermentation sample taken 15 to 30 days longer than room temperature sample. The yeast is increased up to 30 days, and decreased little by little. After 60 days, it remained a few without effectiveness on the Doenjang quality. The low temperature fermentation sample showed brighter than room temperature fermentation sample. Different fermentation condition affected Doenjnag quality, especially, low temperature fermentation sample showed bright color in Doenjnag. So low temperature fermentation must be expected as good method for getting high quality Doenjnag.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2438-2442
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• 2014

A kinetic study is reported for $S_NAr$ reaction of 1-fluoro-2,4-dinitrobenzene (5a) and 1-chloro-2,4-dinitrobenzene (5b) with alkali-metal ethoxides (EtOM, M = Li, Na, K and 18-crown-6-ether complexed K) in anhydrous ethanol. The second-order rate constant increases in the order $k_{EtOLi}$ < $k_{EtO^-}$ < $k_{EtONa}$ < $k_{EtOK}$ < $k_{EtOK/18C6}$ for the reaction of 5a and $k_{EtOLi}$ < $k_{EtONa}$ < $k_{EtO^-$ < $k_{EtOK}$ < $k_{EtOK/18C6}$ for that of 5b. This indicates that $M^+$ ion behaves as a catalyst or an inhibitor depending on the size of $M^+$ ion and the nature of the leaving group ($F^-$ vs. $Cl^-$). Substrate 5a is more reactive than 5b, although the $F^-$ in 5a is ca. $10pK_a$ units more basic than the $Cl^-$ in 5b, indicating that the reaction proceeds through a Meisenheimer complex in which expulsion of the leaving group occurs after the rate-determining step (RDS). $M^+$ ion would catalyze the reaction by increasing either the nucleofugality of the leaving group through a four-membered cyclic transition state or the electrophilicity of the reaction center through a ${\pi}$-complex. However, the enhanced nucleofugality would be ineffective for the current reaction, since expulsion of the leaving group occurs after the RDS. Thus, it has been concluded that $M^+$ ion catalyzes the reaction by increasing the electrophilicity of the reaction center through a ${\pi}$-complex between $M^+$ ion and the ${\pi}$-electrons in the benzene ring.

• Korean Journal of Materials Research
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• v.13 no.6
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• pp.343-346
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• 2003

Photoluminescence(PL), photostimulated luminescence(PSL) and thermoluminescence(TL) in $SrC1_2$:$Eu^{2+}$ , $Na^{+}$ phosphor powder were measured, and the activation energies(trap depth) of traps associated with TL and PSL were investigated. The PL and PSL in the studied sample is due to the $4f^{6}$ 5d\longrightarrow$4f^{7}$transition of $Eu^{ 2+}$. TL glow curve is single peak, and its peak temperature is about 377.2 K. The PL, PSL and TL emission spectra of the phosphors are located in the range of 380∼440 nm, peaking at 408 nm. The activation energy of the PSL trapping center is 0.78 eV and that of the TL trapping center is 0.79 eV. We, thus, suggest that the trapping centers giving rise to the PSL are identical to those giving rise to the TL.

• Carbon letters
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• v.9 no.2
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• pp.137-144
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• 2008

The commercial activated carbons are typically prepared by activation from coconut shell char or coal char containing lots of inorganic impurities. They also have pore structure and pore size distribution depending on nanostructure of precursor materials. In this study, two types of commercial activated carbons were applied for EDLC electrode by removing impurities with acid treatments, and controlling pore size distribution and contents of functional group with heat treatment. The effect of the surface functional groups on electrochemical performance of the activated carbon electrodes was investigated. The initial gravimetric and volumetric capacitance of coconut based activated carbon electrode which was acid treated by $HNO_3$ and then heat treated at $800^{\circ}C$ were 90 F/g and 42 F/cc respectively showing 94% of charge-discharge efficiency. Such a good electrochemical performance can be possibly applied to the medium capacitance of EDLC.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.651-662
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• 2022

The electrochemical impedance spectroscopy(EIS) method was used to evaluate the concrete deterioration process related to chloride-induced steel corrosion with various corrosion levels(initiation, rust propagation and acceleration periods). The impressed current technique, with four total current levels of 0C, 13C, 65C and 130C, was used to accelerate steel corrosion in concrete cylinder samples with w/c ratio of 0.4, 0.5, and 0.6, immersed in a 0.5M NaCl solution. A series of EIS measurements was performed to monitor concrete deterioration during the accelerated corrosion test in this study. Some critical parameters of the equivalent circuit were obtained through the EIS analysis. It was observed that the charge transfer resistance(R_c) dropped sharply as the impressed current increased from 0C to 13C, indicating a value of approximately 10kΩcm². However, the sensitivity of R_c significantly decreased when the impressed current was further increased from 13C to 130C after corrosion of steel had been initiated. Meanwhile, the double-layer capacitance value(C_dl) linearly increased from 50×10^-6μF/cm² to 250×10^-6μF/cm² as the impressed current in creased from 0C to 130C. The results in this study showed that monitoring C_dl is an effective measurement parameter for evaluating the progress of internal concrete damages(de-bonding between steel and concrete, micro-cracks, and surface-breaking cracks) induced by steel corrosion. The findings of this study provide a fundamental basis for developing an embedded sensor and signal interpretation method for monitoring concrete deterioration due to steel corrosion at various corrosion levels.

• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.62-68
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• 2009

The culture conditions to maximize the production of laccase (EC 1.10.3.2) from Fomitopsis pinicola mycelia were investigated. Among the tested media for the enzyme production, mushroom complete medium (MCM ; 2% dextrose, 0.2% peptone, 0.2% yeast extract, 0.05% $KH_2PO_4$, and 0.05% $MgSO_4{\cdot}7H_2O$) showed the highest activity of the enzyme. To optimize the culture condition for the laccase activity, influence of various carbon and nitrogen sources was investigated in MCM. Among various carbon and nitrogen sources, 2% glucose and 0.4% peptone showed the highest production of the enzyme, respectively. For the phosphorus and inorganic source, 0.05% $NaH_2PO_4$ and 0.05% $CaCl_2$ were best for the enzyme activity. The enzyme production was reached to highest level after the cultivation for 8 days at $25^{\circ}C$. Native polyacrylamide gel electrophoresis (PAGE) followed by the laccase activity staining using 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as the substrate was performed to identify the laccase under culture conditions studied. Zymogram analysis of the culture supernatant showed a laccase band with molecular mass of 52 kDa. The optimum pH and temperature for the enzyme activity were $80^{\circ}C$ and pH 3.0.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.363-363
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• 2008

The development of dry etching process for sapphire wafer with plasma has been key issues for the opto-electric devices. The challenges are increasing control and obtaining low plasma induced-damage because an unwanted scattering of radiation is caused by the spatial disorder of pattern and variation of surface roughness. The plasma-induced damages during plasma etching process can be classified as impurity contamination of residual etch products or bonding disruption in lattice due to charged particle bombardment. Therefor, fine pattern technology with low damaged etching process and high etch rate are urgently needed. Until now, there are a lot of reports on the etching of sapphire wafer with using $Cl_2$/Ar, $BCl_3$/Ar, HBr/Ar and so on [1]. However, the etch behavior of sapphire wafer have investigated with variation of only one parameter while other parameters are fixed. In this study, we investigated the effect of pressure and other parameters on the etch rate and the selectivity. We selected $BCl_3$ as an etch ant because $BCl_3$ plasmas are widely used in etching process of oxide materials. In plasma, the $BCl_3$ molecule can be dissociated into B radical, $B^+$ ion, Cl radical and $Cl^+$ ion. However, the $BCl_3$ molecule can be dissociated into B radical or $B^+$ ion easier than Cl radical or $Cl^+$ ion. First, we evaluated the etch behaviors of sapphire wafer in $BCl_3$/additive gases (Ar, $N_2,Cl_2$) gases. The behavior of etch rate of sapphire substrate was monitored as a function of additive gas ratio to $BCl_3$ based plasma, total flow rate, r.f. power, d.c. bias under different pressures of 5 mTorr, 10 mTorr, 20 mTorr and 30 mTorr. The etch rates of sapphire wafer, $SiO_2$ and PR were measured with using alpha step surface profiler. In order to understand the changes of radicals, volume density of Cl, B radical and BCl molecule were investigated with optical emission spectroscopy (OES). The chemical states of $Al_2O_3$ thin films were studied with energy dispersive X-ray (EDX) and depth profile anlysis of auger electron spectroscopy (AES). The enhancement of sapphire substrate can be explained by the reactive ion etching mechanism with the competition of the formation of volatile $AlCl_3$, $Al_2Cl_6$ or $BOCl_3$ and the sputter effect by energetic ions.

• Journal of the Korean Society for Marine Environment & Energy
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• v.4 no.3
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• pp.16-27
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• 2001

We have studied the phosphorus geochemistry in sediments from anoxic environments of Lake Shihwa. The dominant sedimentary phosphorus forms were detrital apatite P and Al-bound p, whereas the amount of Fe-bound P was low because of anoxic condition. Based on the correlation between TP(Total Phosphorus) and OC(Organic Carbon), the behavior of sedimentary phosphorus was influenced by organic matters. It shows that dissolved and solid phosphorus concentrations, the flux of phosphate and the correlation coefficients between sedimentary phosphorus and organic matter In St. Cl were higher than those in St. C2. The results indicate that the concentrations and distributions of phosphorus In sediments were controlled by organic matters.

• Applied Biological Chemistry
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• v.25 no.2
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• pp.67-74
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• 1982

Morphology, physicochemical properties, pasting properties in the presence of various anionic ions and aging of gels of Akibare (Japoica type) and Milyang 23 (Indica type) rice starch were studied, Both starches. were polygonal with length in the range of $3{\sim}6{\mu}m$. Starch granules of Akibare were somewhat smaller than those of Milyang 23. X-ray diffraction study demonstrated that peak shape and intensity were significantly different between the two starches. Akibare and Milyang 23 rice starch had amylose content of 18.5 and 19.5% and water binding capacity of 106 and 100%, respectively. Milyang 23 rice starch had a higher swelling power than Akibare starch. A relationship between percent solubility and swelling power implied that bonding forces within the granules of the both starches were different. The optical transmittance of 0.1% suspension of the two starches increased rapidly from $60^{\circ}C$. In the range of $60{\sim}90^{\circ}C$, the two starches showed a single gelatinization pattern. Amylograms of the two starches in the presence of various anionic ions showed that pasting temperature and peak temperature were progressively increased in the order of SCN-${SO_4}^=$. SCN- and I- ions increased the peak height of Akibare rice starch while only SCN- ion was effective for Milyang 23 rice starch. There were no differences in the rates of retrogradation of 45% gels of the two starches stored at $21^{\circ}C$.

• Bulletin of the Korean Chemical Society
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• v.16 no.10
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• pp.912-915
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• 1995

Ornidazole, C7H10ClN3O3, crystallizes in the triclinic, space group P1^, with a=13.605(2), b=14.054(1), c=8.913(5) Å, α=71.59(2), β=78.73(2), γ=64.86(1)°, μ=3.26 cm-1, Dc=1.499 g/cm3, Dm=1.497g/cm3, F(000)=684, and z=6. Intensities for 2693 unique reflections were measured on a CAD4 diffractometer with graphite-monochromated Mo-Kα radiation. The structure was solved by direct method and refined by block-diagonal least squares to a final R of 0.081 (Rw=0.047) for 1952 reflections with Fo>3σ (Fo). The asymmetric unit contains three independent molecules of the title compound. The bond lengths and bond angles are comparable with the values found in the other nitro-substituted compounds. The nitro groups are rotated (6.9°, 6.6°, 2.6° for the three independent molecule, respectively) about the C-N axes from the imidazole planes. The crystal structures are linked by two intermolecular hydrogen bonds of O-H---N type and one intermolecular hydrogen bond of O-H---O type.