• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.100-109
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• 1997

The objectives of this study was to decrease pollutions of bleaching effluent and was to enhanced brightness of non-chlorine bleached pulps by xylanase treatments. Xylanase cloned Esherichacoli(E. coli) capable of each of endo, exo-xylanase and acetyl-esterase were obtained from Bacillus stearothermophillus. These xylanase was maintained high activity in alkali and high temperature. Especially endo-xylanase would be more active in $60^{\circ}C$ and pH 11. Xylanase pretreatment(X) of unbleached pulp increased brightness, and decreased the degree of delignification. The degree of increase in brightness of pulp due to xylanase pretreatment was similar to non-enzyme treated pulp, regardless of the amount of enzyme added. Therefore, the addition of xylanase of 2 unit was recommended when considering costs of enzyme. The pulp bleached XO sequence had higher brightness and lower Kappa no, than O bleached pulp, while pulp bleached XP sequence had similar brightness and Kappa no. with P bleached pulp. In XOC/D, XOZ and XOP bleaching sequences, brightness and degree of delignification were improved. The C/D and Z stage bleached pulp was good effect on rate of raise in brightness and Kappa no., but P stage bleached pulp had similar level in non-enzyme treated bleaching sequence.

• Journal of Animal Science and Technology
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• v.66 no.5
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• pp.999-1009
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• 2024

The impact of dietary non-starch polysaccharides (NSP) on performance and carcass traits of broilers fed wheat-bran substituted into corn-soybean meal-based diets supplemented with xylanase was investigated. A total of 280 (7-day-old) Ross 308 broilers were randomly allotted to one of five dietary treatments with 8 replicates, 7 chicks per pen. Treatments were; i) CON: Control diet, ii) CON-X (CON + 3,000 U/kg xylanase), iii) L-X: low NSP (2% wheat bran in CON + 3,000 U/kg xylanase), iv) M-X: medium NSP (4% wheat bran in CON + 3,000 U/kg xylanase), v) H-X: higher NSP (8% wheat bran in CON+ 3,000 U/kg xylanase). Birds fed the H-X diet increased (p < 0.05) daily gains, and average daily feed intake and had marginally improved body weights (p = 0.074) on day 35. Relatively, the H-X diet tended to increase the average daily gains (p = 0.053; p = 0.073) of birds during the grower phase (d 24-35) and the entire experimental period (d 8-35), respectively. Moreover, there were no significant differences among treatments in the feed conversion ratio of birds throughout the entire experiment period. Birds fed diets CON-X, L-X, and M-X had improved (p < 0.05) the ileal digestibility of energy on d 24 and 35 compared to those fed the H-X diet. Furthermore, birds fed diet CON-X improved (p < 0.05) N digestibility on d 24. Improved carcass moisture content and lowered crude fat of leg meat (p < 0.05) were noted in birds fed the diet M-X and H-X on d 35, respectively. The intestinal viscosity was reduced (p < 0.05) in xylanase-supplemented treatments CON-X, L-X, M-X, and H-X diets when compared to CON. Our results suggest that supplementing 3,000 U/kg xylanase in a higher NSP (8% wheat bran substituted level) diet could improve the intestinal viscosity and growth performance of broilers.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1003-1007
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• 2005

We demonstrate color video displays driven by carbon nanotube electron field emitters. These nanotubes are incorporated into the device by selective growth using low temperature chemical vapor deposition. The device structure is simple and inexpensive to fabricate, and a 45 V switching voltage enables the use of low cost driver electronics. The prototype units are sealed 4.6” diagonal displays with 726 um pixels. They represent a piece of a 42” diagonal 1280x720 high definition television. The carbon nanotube growth process is performed as the last processing step and creates nanotubes ready for field emission. No activation post-processing steps are required, so chemical and particulate contamination is not introduced. Control of the nanotube dimension, orientation, and spatial distribution during growth enables uniform, highquality, color video performance.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.3
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• pp.251-260
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• 2014

Biomass burning is one of the significant emission source of PM and CO, but a few studies are reported in Korea. Air pollutants emission from biomass burning such as wood stove and boiler, and wood-pellet stove and boiler were estimated in this study. Activity levels related to biomass burning such as fuel types, amount of fuel loading, and location and temporal variation were investigated by field survey over Korea. Fuel loadings were 14.9 kg/day for wood stove, 31.3 kg/day for wood boiler, 12.8 kg/day for wood-pellet stove, 32.5 kg/day for wood-pellet boiler during the season of active use. These were mostly burned in winter season from october to april of next year. Estimated annual emissions from wood stove & boiler were CO 76,677, $NO_x$ 710, $SO_x$ 70, VOC 20,941, TSP 6,605, PM10 2,921, PM2.5 1,851, and NH3 7 ton/yr, respectively. Emissions from wood-pellet stove and boiler were CO 32,798, $NO_x$ 1,830, $SO_x$ 25, VOCs 5,673, TSP 629, PM10 457, PM2.5 344, and $NH_3$ 2 ton/yr, respectively. When the emission estimates are compared with total emissions of the national emission inventory (CAPSS: Clean Air Policy Support System), Those occupy 12.5%, 2.8% of total national emission for CO and PM10, respectively. These results show wood and wood-pellet burning appliances were one of the major source of air pollution in Korea. In future, these types of heaters need to be regulated to reduce air pollution, especially in suburb area.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.2
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• pp.118-136
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• 2010

Photochemical characteristics of ozone ($O_3$) and its precursors such as $O_3$ budget and $O_3-NO_x$-VOC sensitivity were analyzed in different physico-chemical properties of air masses around the Mexico City Metropolitan Area (MCMA) using aircraft observations during March 2006. The physico-chemical properties of air masses were categorized into 5 groups: boundary layer (BL), biomass burning (BB), free tropospheric continent (FTCO) and marine (FTMA), and Tula industrial complex (TIC). Results from the $O_3$ budget analysis indicated that $O_3$ production for BL, FTCO, and FTMA (for BB and TIC) was mainly controlled by a photochemical production pathway, a reaction of NO with $HO_2$ (with $RO_2$), while the main pathway of photochemical $O_3$ destruction for BL, FTCO, and FTMA (for BB and TIC) was a reaction of $HO_2$ with $O_3$ (of $H_2$ with $O^1$(D)). In addition, most of air mass categories (especially FTCO) were estimated to be $NO_x$-sensitive for $O_3$ production with lower $NO_y$, higher ratios of the other indicator species (e.g., $O_3/(NO_y-NO_x$), $H_2O_2/HNO_3$, etc.), and the lower removal rate of radicals ($\leq$0.5) by the reaction of OH with $NO_2$ than those of the VOC-sensitive condition.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.6
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• pp.499-502
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• 2008

In this work, Ga-doped ZnO (GZO) thin films for gas sensor application were deposited on low temperature co-fired ceramics (LTCC) substrates, by RF magnetron sputtering method. The LTCC substrate is one of promising materials for this application since it has many advantages (e.g., low cost production, high manufacturing yields and easy realizing 3D structure etc.). The LTCC substrates with thickness of $400\;{\mu}m$ were fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The structural properties of the fabricated GZO thin film with thickness of 50 nm is analyzed by X-ray diffraction method (XRD) and field emission scanning electron microscope (FESEM). The film shows good adhesion to the substrate. The GZO gas sensors are tested by gas measurement system and show fast response and recovery characteristics to $NO_x$ gas that is 27.2 and 27.9 sec, recpectively.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.10
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• pp.1393-1398
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• 2011

Four 4-month old Charolais${\times}$Dorset male sheep (initial liveweight $25.0{\pm}1.1\;kg$), fitted with rumen and abomasal fistulas and nourished by total intragastric infusions, were used to study the relationships between methionine (Met) supply, nitrogen (N) retention and plasma insulin-like growth factor-I (IGF-I). Four graded levels of Met, i.e. 0 g/16 g N, 1.76 g/16 g N, 3.52 g/16 g N and 7.04 g/16 g N, were infused into abomasums as experimental treatments. The sheep and treatments were allocated in a $4{\times}3$ incomplete Latin square design (Yudon square design). The experiment lasted 3 periods and each period was 10 days. Quadratic correlations were found between Met level (x, g/16 g N) and N retention (y, g/d): y = $-0.03x^2$+0.41x+2.62, $r^2$ = 0.66, n = 12, p = 0.008, and between methionine level (x, g/16 g N) and plasma IGF-I concentration (y, ng/ml): y = $0.80x^2$-4.53x+190.24, $r^2$ = 0.51, n = 12, p = 0.009. No significant correlation was found between plasma IGF-I (x, ng/ml) and N retention (y, g/d) (p>0.05). It was concluded that Met level had a significant influence on N retention and plasma IGF-I concentration whereas IGF-I might not be an important mediator in the regulation of N metabolism by Met in growing sheep nourished by total intragastric infusions.

• Journal of the Korean Chemical Society
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• v.61 no.4
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• pp.163-167
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• 2017

Along with the progress of white LED technology, red phosphors have become increasingly important in industry and academia, and a more specific demand has steadily increased in the market. Red phosphors are used in high efficiency and high rendering LED lightings. However, using red phosphors with $Eu^{2+}$ activators caused color rewarming and reduced emission intensity in white LED chips due to strong reabsorption in the green or yellow wavelength range caused by the 4f-5d transition. $Mn^{4+}$ doped phosphors which have no such drawbacks and which can further improve the color rendering index (CRI) are now of great interest. However, $Mn^{4+}$-doped phosphors have a disadvantage in that the emission wavelength is determined depending on the host due to the $^2E_g{\rightarrow}^4A_2$ transition. In this study, the $SrO-BaO-GeO_2$ solid-solution was selected, and $Sr_{1-x}B_axGe_4O_9:Mn^{4+}{_{0.005}}$ ($0{\leq}x{\leq}1$) phosphors were synthesized and characterized. This led to a versatile color tuning in LED technology.

• Journal of Ocean Engineering and Technology
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• v.13 no.4 s.35
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• pp.151-158
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• 1999

A model harbour with Plan scale of $1.08{\times}1.08m$ is built on a tidal tank using a Froude relationship from a real harbour($432{\times}432m$). Velocity components are measured by a ultrasonic velocity meter and flow structure is then predicted using a 2-D depth integrated hydrodynamic model. In the finite difference model implemented in this study, various wall boundary conditions, i.e. no-slip, free-slip, partial-slip and semi-slip are used to represent turbulent diffusion terms, e.g. ${\partial}^2U_{ij}/{\partial}x^2\;or\;{\partial}^2U_{ij}/{\partial}y^2$. These conditions are focused to investigate their influence on the flow structure along the wall and basin of the harbour with aspect ratio of unity, i.e. Length/Breadth. Numerical experiments are compared with the measurements and used to analyse flow patterns in the basin during tidal cycles. It is shown from the results that no-slip closed boundary condition is the most appropriate method with respect to the location of the eddy centre, although the condition underestimates velocity components along the wall.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.507-514
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• 1994

Acetyl xylan esterase was produced by E. coli HB101 harboring a recombinant plasmid pKMG6 which contained the estI gene of Bacillus stearothermophilus. The maximum production was observed when the E. coli strain was grown at 37$\circC for 12 hours in the medium containing 0.5% acetyl xylan, 1.0% tryptons, 1.0% sodium chloride, and 0.5% yeast extract. The esterase produced was purified to homogeneity using a combination of ammonium sulfate fractionation, DEAE Sepharose CL-6B ion exchange chromatography and Sephacryl S-200 gel filtration. The native enzyme had an apparent molecular mass of 60 kd and was composed of two identical subunits of 29 kd. The N-terminal amino acid sequence of the polypeptide was Ala-X-Leu-Gln- Ile-Gln-Phe-X-X-Gln. The acetyl esterase displayed a pH optimum of 6.5 and a temperature opti- mum of 45$\circC. The heavy metal ions such as Ag$^{++}$, Hg$^{++}$ and Cu$^{++}$ inhibited nearly completely the activity of the esterase, and no specific metal ion was found to be required for the enzyme activity. The enzyme readily cleaved MAS, $\beta$-D-glucose pentaacetate, $\alpha$-naphthyl acetate, $\rho$-nitrophenyl acetate as well as acetyl xylan, but had no activity on $\rho$-nitrophenyl propionate, $\beta$-nitrophenyl butyrate or $\beta$-nitrophenyl valerate. The Km and Vmax values for MAS were 2.87 mM and 11.55 $\mu$mole/min, respectively. Synergistic behavior was demonstrated with a combination of xylanase and esterase from B. stearothermophilus in hydrolyzing acetyl xylan.