• KSBB Journal
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• v.19 no.1
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• pp.50-56
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• 2004

The aim of this work was to investigate the purification and characterization dixoygenases isolated from Delftia sp. JK-2, which could utilize aniline, benzoate, and p-hydroxybenoate as sole carbon and energy source. Catechol 1,2-dioxygenase (C1, 2O), catechol 2,3-dioxygenase(C2, 3O), and protocatechuate 4,5-dioxygenase(4,5-PCD) were isolated by benzoate, aniline, and p-hydroxybenzoate. In initial experiments, several characteristics of C1 ,2O, C2, 3O, and 4,5-PCD separated with ammonium sulfate precipitation, DEAE-sepharose, and Q-sepharose were investigated. Specific activity of C1 ,2O, C2, 3O, and 4,5-PCD were approximately 3.3 unit/mg, 4.7 unit/mg, and 2.0 unit/mg. C1 ,2O and C2, 3O demonstrated their enzyme activities to other substrates, catechol and 4-methylcatechol. 4,5-PCD showed the specific activity to the only substrate, protocatechuate, but the substrates(e.g., catechol, 3-methylcatechol, 4-methylcatechol, 4-chlorocatechol, 4-nitrocatechol) did not show any specific activities in this work. The optimum temperature of C1, 2O, C2, 3O, and 4,5-PCD were 30$^{\circ}C$, and the optimal pHs were approximately 8, 8, and 7, respectively. Ag$\^$+/, Hg$\^$+/, Cu$\^$2+/ showed inhibitory effect on the activity of C1, 2O and C2, 3O, but Ag$\^$+/, Hg$\^$+/, Cu$\^$2+/, Fe$\^$3+/ showed inhibitory effect on the activity of 4,5-PCD. Molecular weight of the C1, 2O, C2, 3O, and 4,5-PCD were determined to approximately 60 kDa,35 kDa, and 62 kDa by SDS-PAGE.

• Journal of the Korean Society of Combustion
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• v.16 no.3
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• pp.33-40
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• 2011

Combustion experiments were conducted at three different fuels ($CH_4$, $C_2H_4$ and $C_3H_8$) to investigate the effects of combustor pressure (30 ~ -30 kPa) on combustion charateristics and reaction zone structure. Regardless of the fuels, emission index of CO (EICO) increased with decreasing combustor pressure, and EICO of $C_2H_4$ was mostly affected by changing combustor pressure at subatmospheric pressure. In order to observe reaction zone, $OH^*$, $CH^*$ and ${C_2}^*$ chemiluminescence intensity were measured. The sequence of the chemiluminescence intensity peak position was affected by chemical characteristics of fuels rather than changing combustor pressure. The emission zone thickness of $C_2H_4$ and $C_3H_8$, defined by the full width at half maximum (FWHM) of $CH^*$ intensity profile, were increased with decreasing combustor pressure. however, the thickness of $C_2H_4$ exhibited the opposite tendency due to the characteristics of the fuel as the bond structure.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.10
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• pp.495-499
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• 2004

Characteristics of ohmic Ni/Si/Ni contacts to n-type 4H-SiC are investigated systematically. The ohmic contacts were formed by annealing Ni/Si/Ni sputtered sequentially The annealings were performed at 950℃ using RTP in vacuum ambient and N₂ ambient, respectively. The specific contact resistivity(p/sub c/), sheet resistance(R/sub s/), contact resistance (R/sub c/) transfer length(L/sub T/) were calculated from resistance(R/sub T/) versus contact spacing(d) measurements obtained from TLM(transmission line method) structure. While the resulting measurement values of sample annealed at vacuum ambient were p/sub c/ = 3.8×10/sup -5/Ω㎠, R/sub c/ = 4.9 Ω and R/sub T/ = 9.8 Ω, those of sample annealed at N₂ ambient were p/sub c/ = 2.29×10/sup -4/Ω㎠, R/sub c/ = 12.9 Ω and R/sub T/ = 25.8 Ω. The physical properties of contacts were examined using XRD 3nd AES. The results showed that nickel silicide was formed on SiC and Ni was migrated into SiC. This result indicates that Ni/Si/Ni ohmic contact would be useful in high performance electronic devices.

• Advances in nano research
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• v.10 no.4
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• pp.339-347
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• 2021

In the framework of the density functional theory combined with the method of non-equilibrium Green functions (DFT + NEGF), the electric transport properties of a one-dimensional nanodevice consisting of telescoping polyprismanes with various types of electrical conductivity were studied. Its transmission spectra, density of state, current-voltage characteristic, and differential conductivity are determined. It was shown that C_[14,17], C_[14,11], C_[14,16], C_[14,10] show a metallic nature, and polyprismanes C_[14,5], C_[14,4] possess semiconductor properties and has a band gap of 0.4 eV and 0.6 eV, respectively. It was found that, when metal C_[14,11], C_[14,10] and semiconductor C_[14,5], C_[14,4] polyprismanes are coaxially connected, a Schottky barrier is formed and a weak diode effect is observed, i.e., manifested valve (rectifying) property of telescoping polyprismanes. The enhancement of this effect occurs in the nanodevices C_[14,17] - C_[14,11] - C_[14,5] and C_[14,16] - C_[14,10] - C_[14,4], which have the properties of nanodiode and back nanodiode, respectively. The simulation results can be useful in creating promising active one-dimensional elements of nanoelectronics.

• Journal of IKEEE
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• v.18 no.4
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• pp.620-624
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• 2014

In this study, the electrical characteristics of Ni/CNT/$SiO_2$ structures were investigated in order to analyze the mechanism of carbon nanotubes in 4H-SiC MIS device structures. We fabricated 4H-SiC MIS capacitors with or without carbon nanotubes. Carbon nanotubes were dispersed by isopropyl alcohol. The capacitance-voltage (C-V) is characterized at 300 to 500K. The experimental flat-band voltage ($V_{FB}$) shift was positive. Near-interface trapped charge density and oxide trapped charge density values of Ni/CNT/$SiO_2$ structure were less than values of reference samples. With increasing temperature, the flat-band voltage was negative. It has been found that its oxide quality is related to charge carriers or defect states in the interface of 4H-SiC MIS capacitors. Gate characteristics of 4H-SiC MIS capacitors can be controlled by carbon nanotubes between Ni and $SiO_2$.

• Journal of Food Hygiene and Safety
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• v.23 no.4
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• pp.304-308
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• 2008

We investigated temperature management for refrigerated foods in large discount markets, department stores, and convenience stores. Eleven stores in the Seoul area were used to examine temperature maintenance for frozen and refrigerated foods, including soybean curds (tofu), fish surimi, mook, wet noodles, kimbab, and salads. The surficial and central temperatures of foods in a refrigerator and a freezer were examined. While the difference between the highest ($7.5^{\circ}C$) and the lowest ($6.4^{\circ}C$) temperature spaces in a refrigerator was $1.1^{\circ}C$, the corresponding difference between the highest ($8.9^{\circ}C$) and lowest ($7.5^{\circ}C$) food surface temperatures was $1.4^{\circ}C$. The average temperatures of both chilled food surfaces and refrigerator spaces were $7^{\circ}C$ (max. $22.9^{\circ}C$) and 8.2 degrees C (in. $-0.4^{\circ}C$), respectively. The temperatures of chilled food surfaces were $6.1{\times}10.6^{\circ}C$ for soybean curds, $6{\sim}12.3^{\circ}C$ for fish paste, $2.3{\times}18.2^{\circ}C$ for kimbab, $4.6{\times}12.2^{\circ}C$ for salads, $3.4{\times}12.6^{\circ}C$ for wet noodles, and $7.1{\times}19^{\circ}C$ for mook. Our results indicate that chilled foods require careful management for storage at temperatures below $10^{\circ}C$ with careful recording of the warmest area of the refrigerator.

• Journal of dental hygiene science
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• v.9 no.4
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• pp.427-433
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• 2009

Nuclear factor I-C (NFI-C) null mice demonstrated aberrant odontoblast differentiation and abnormal dentin formation. In order to elucidate the mechanisms responsible for these changes, we evaluated the expression of dentin matrix gene after over-expression and inactivation of NFI-C in MDPC-23 cells by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Collagen type I (Col I), osteocalcin (OC), and dentin sialophosphoprotein (DSPP) expression was decreased after inactivation of NFI-C. However, bone sialoprotein (BSP) expression was dramatically increased after inactivation of NFI-C. ALP and DMP4 expression was not changed after inactivation of NFI-C. The expression of alkaline phoshatase (ALP) and dentin matrix protein 4 (DMP4) was increased after over-expression of NFI-C, while Col I, OC, DSPP, and BSP expression was decreased. These findings suggest that odontoblasts after loss of NFI-C lost the phenotype of odontoblasts and acquired those of osteoblasts.

• Korean journal of food and cookery science
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• v.17 no.4
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• pp.338-343
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• 2001

This study was carried out to analyze the characteristics of Dongchimi(watery radish kimchi) juice while fermenting the samples prepared at various salt concentrations(2, 2.5, and 3 %) and fermentation temperatures(4$^{\circ}C$, 12$^{\circ}C$, and 12$^{\circ}C$ for 12 hr followed by 4$^{\circ}C$). The changes in colour, total vitamin C and free sugar contents were analyzed, and sensory evaluation was performed. As the fermentation proceeded, the “L” value was decreased and “a” and “b” values were increased in all samples. Total vitamin C contents increased up to 26-33 days and decreased thereafter in the samples fermented at 4$^{\circ}C$ and those fermented at 12$^{\circ}C$ followed by 4$^{\circ}C$. In Dongchimi fermented at 12$^{\circ}C$, vitamin C contents increased up to 12-15 days. Glucose, fructose and sucrose were detected in Dongchimi juice. The total content of free sugars in Dongchimi juice was the highest in the samples fermented at 12$^{\circ}C$ followed by 4$^{\circ}C$ . Sensory evaluation was performed for sour taste, salty taste, carbonated flavor, offensive odor, overall preference and clearance of the juice. In overall preference, Dongchimi juice fermented at 12$^{\circ}C$ followed by 4$^{\circ}C$ was the best.

• Journal of the East Asian Society of Dietary Life
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• v.12 no.6
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• pp.554-565
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• 2002

The purpose of this study is to investigate the effect of raw Cassia tora L. powder added-diets on reducing cadmium accumulation in rats. The experimental animals were Sprague-Dawley family(♂, 4 weeks) which was classified into normal group CN, compared group CS, Cd-added group Cl and groups C2, C3, C4 in which 0.5, 1.0 and 1.5% of the Cassia tora L. powder are added, respectively. The growth rate and food efficiency ratio, and the amounts of accumulated cadmium in rats for S weeks were measured and analyzed. The results are as follows; 1. The rates of weight gain decreased in the order of C3>C2>C4>Cn>Cs>Cl groups, and Cl group to which only cadmium water had been fed was the lowest among them. The correlation between groups Cl and C3 was significantly different at the 1% level. 2. Food efficiency ratio(FER) decreased in the order of C3>C2>Cs>Cn>C4>Cl, and the FERs of C3, C2, CS, CN and C4 are greater than that of Cl by 22.87, 19.59, 18.54, 14.20 and 13.17%, respectively. 3. As for the Cassia tora L. powder-added groups, the amounts of cadmium accumulated in organs and tissues, that is, the brain, heart, spleen, liver, lungs, testicles. kidney, femoral muscle and leg bones were 0.45 $\pm$ 0.04 to 0.83$\pm$0.04, 1.68$\pm$0.02 to 2.16$\pm$0.02, 3.26$\pm$0.05 to 4.62$\pm$0.27, 37.52$\pm$0.09 to 47.71$\pm$0.73, 1.07$\pm$0.10 to 1.66$\pm$0.04, 1.04$\pm$0.06 to 1.24$\pm$0.08, 36.79$\pm$0.20 to 39.61 $\pm$0.53, 0.87$\pm$0.02 to 1.00$\pm$0.02 and 0.65$\pm$0.17 to 1.27 $\pm$ 0.06 $\mu\textrm{g}$/g, respectively. 4. The accumulated Cd content for C4 was the lowest among Cassia tora L. powder-added groups. When the results for C4 are compared with those for Cl, it is observed that each cadmium content accumulated in the brain, heart spleen, liver, lungs, testicles, kidney. femoral muscle and leg bones is dropped by 49.03, 22.56, 36.02, 35.75, 41.75, 36.20, 37.00, 22.77 and 56.67 %, respectively. On the other hand. the accumulated Cd content increased in the order of brain

• Korean Journal of Food Science and Technology
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• v.41 no.3
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• pp.251-257
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• 2009

The effects of temperature variations during storage on the quality characteristics of muskmelons (Cucumis melo L.) were investigated. In samples stored at $4^{\circ}C$ and $10^{\circ}C$, weight losses were almost 2.9- and 3.4-fold higher, respectively, compared to samples stored at $0^{\circ}C$. Soluble solids slightly increased except in the samples stored at $10^{\circ}C$, but acidity decreased over the entire storage period. Firmness decreased with storage time, but the samples stored at $0^{\circ}C$ had a lesser decrease in firmness than the samples stored at other temperatures. Water loss from the muskmelon stalk was most inhibited, and vitamin C content was maintained for the longest period, with storage at $4^{\circ}C$. Mineral contents (Ca, Na, Fe, Mg, K) were best maintained in muskmelon samples stored at $10^{\circ}C$ for 15 days, but levels had decreased by 30 days. Microbiological quality was not appreciably different at any storage temperature at 18 days; however, samples stored at $4^{\circ}C$ and $10^{\circ}C$ had deteriorated by 25 days. The results of sensory evaluations indicated that taste was best retained in samples stored at $10^{\circ}C$ for 15 days, although changes in taste were evident at all storage temperatures. When the samples were stored over 22 days at $10^{\circ}C$, retention of texture and overall acceptability were more inferior compared to samples stored at $0^{\circ}C$ and $4^{\circ}C$. These results suggest that storage at $4^{\circ}C$ can be used to reduce deterioration in muskmelons without significant loss of their quality attributes.