• YAKHAK HOEJI
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• v.54 no.5
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• pp.398-402
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• 2010

[ ${\alpha}$ ]Glucosidase inhibitor is a target in the treatment of type II diabetes through the mainly inhibition of glucose levels after meals. In this study, we purified steppogenin and oxyresveratrol from the stem of Morus alba L. and examined their inhibitory activity against yeast ${\alpha}$-glucosidase. Steppogenin and oxyresveratrol were inhibited yeast ${\alpha}$-glucosidase in a dose dependent manner. The $IC_{50}$ activities (50% inhibition) were 34.4 and 9.3 ${\mu}M$, respectively. The kinetic inhibition of steppogenin showed noncompetitive inhibition ($K_m:1.1{\times}10^{-3}M$; $K_i:1{\times}10^{-5}M$), meanwhile oxyresveratrol showed competitive inhibition ($K_m:4.3{\times}10^{-3}M$; $K_i:3.4{\times}10^{-6}M$) against yeast ${\alpha}$-glucosidase. These results indicate that steppogenin and oxyresveratrol are noncompetitive and competitive inhibitors, respectively, against yeast ${\alpha}$-glucosidase.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.149-160
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• 2015

This study aims to estimate the forest volumes of the upper region of Nam-Han River in ecosystem zoning by forest types and age classes, and to suggest the optimal estimation method through the comparison of the standard errors according to the spatial unit. In the estimation of forest volumes, we used both of direct estimation, which uses sample plots of the target area only, and synthetic estimation, which includes sample plots of the expanded areas as well as those of the target area. As for the spatial expansion, we applied four standards for synthetic estimator: Mountainous zone, Neighbor ecosystem region, Gangwon province, and Buffer zone. The results show that average forest volume per ha, calculated by direct estimation, was $143.5m^3/ha$, while that by synthetic estimation with each standard, was estimated at $146.9m^3/ha$ by Gangwon province, $144.8m^3/ha$ by Buffer zone, $139.8m^3/ha$ by Neighbor ecosystem region, and $138.6m^3/ha$ by Mountainous zone, respectively. The standard errors of direct estimation was $1.79m^3/ha$, while those of synthetic estimation showed not a great difference among the errors. Meanwhile, considering the standard errors by forest type, the lowest was ${\pm}2.3m^3/ha$ of broad-leaved forest, followed by ${\pm}3.3m^3/ha$ of mixed forest, and ${\pm}4.8m^3/ha$ of coniferous forest.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.255-265
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• 2017

We have determined the optimal pumping rate of the PW-2 water well (depth=100 m) at Imgokri, Sangju City. Cutting analysis and geophysical logging data reveal water-producing horizons at 26.1-26.5, 28.0-30.0, 33, 58, and 71 m. For pumping rates of 40, 55, 70, 90, and $132m^3/d$ over 70 days, the estimated drawdown from the PW-2 well was 6.48, 11.56, 18.07, 28.99 and 60.26 m, respectively. During a constant-rate pumping test at a rate of $117m^3/d$, the cone of depression intersected an impermeable boundary after 120-150 min of pumping. Therefore, we consider the critical pumping rate for well PW-2 to be $90m^3/d$. After pumping at $90m^3/d$ for 70 days, the calculated drawdown was 28.82-31.27 m. We suggest an optimal pumping rate for well PW-2 of $70-90m^3/d$, as the optimal pumping rate should be similar to the critical pumping rate. Sharp increases in the slope of the time-drawdown relationship, dissolved oxygen concentrations, and oxidation-reduction potential during the constant-rate pumping test indicate the limited development of bedrock aquifers around PW-2.

• Journal of Korean Society for Atmospheric Environment
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• v.25 no.1
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• pp.46-56
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• 2009

The main purpose of this study was to investigate air quality trends of ambient aerosol with obtaining size-fractionated information. The suspended particulate matters were continuously collected on membrane filters and glass fiber filters by an 8-stage cascade impactor for 2 years (Sep. 2005 $\sim$ Sep. 2007) in Kyung Hee University-Global Campus. 8 ionic species ($Na^+$, ${NH_4}^+$, $K^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, ${NO_3}^-$, and ${SO_4}^{2-}$) were analyzed by an IC after performing proper pretreatments of each sample filter. The average concentration levels of each ion were $9.24{\mu}g/m^3$ of ${SO_4}^{2-}$, $7.35{\mu}g/m^3$ of ${NO_3}^-$, $2.81{\mu}g/m^3$ of ${NH_4}^+$, $2.11{\mu}g/m^3$ of $Ca^{2+}$, $1.65{\mu}g/m^3$ of $Cl^-$, $1.87{\mu}g/m^3$ of $Na^+$, $0.80{\mu}g/m^3$ of $Mg^{2+}$, and $0.54{\mu}g/m^3$ of $K^+$, respectively. The distribution pattern of $Na^+$, $Mg^{2+}$, $Ca^{2+}$, $Cl^-$, and ${NO_3}^-$ was bi-modal and two peaks appeared in the range of $0.4{\sim}0.7{\mu}m$ and $3.3{\sim}4.7{\mu}m$, respectively. On the other hand, ${SO_4}^{2-}$, ${NH_4}^+$, and $K^+$ showed patterns of uni-modal distribution, mostly abounded in the fine mode group.

• Reproductive and Developmental Biology
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• v.35 no.4
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• pp.469-473
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• 2011

These study was carried out to investigate the effects of the supplementation with sodium nitroprusside (SN) and nitric oxide (NO) of canine oocytes on IVM rates. Oocytes were incubated in TCM-199 supplement with at 0.03~0.10 mM SN and 0.3~1.0 mM NO for 48 hrs. Oocytes were transferred to 50 ul drops of maturation medium covered mineral oil and cultured in a $CO_2$ incubator (5% $CO_2$, 95% air, $38^{\circ}C$). The in vitro maturation rate of oocytes cultured for 48 hrs in TCM-199 medium supplement with 0.03, 0.05, 0.07, 0.10 mM SN were $25.9{\pm}3.5%$, $36.4{\pm}3.2%$, $33.3{\pm}3.5%$, $28.8{\m}3.2%$, respectively. The in vitro maturation rate of oocytes cultured for 48 hrs in TCM-199 medium supplement with 0.03~0.07 mM SN were significantly increased compare to the control ($26.0{\pm}2.2%$). The in vitro maturation rates of oocytes cultured for 48 hrs in TCM-199 medium supplement with 0.3, 0.5, 0.7, 1.0 mM NO were $28.0{\pm}4.2%$, $36.5{\pm}3.6%$, $30.0{\pm}3.8%$, $19.2{\pm}3.5%$, respectively. The in vitro maturation rate of oocytes in TCM-199 medium supplemented with 0.3 and 0.5 mM NO were significantly increased compare to the control ($26.0{\pm}2.2%$). The in vitro maturation rates of oocytes cultured for 12~48 hrs in TCM-199 medium supplement with 0.05 mM SN were $26.0{\pm}3.2%$, $28.0{\pm}3.4%$, $38.0{\pm}3.2%$, respectively. The in vitro maturation rate of oocytes cultured for 12~48 hrs in TCM-199 medium supplement with 0.5 mM NO were $22.0{\pm}3.0%$, $30.0{\pm}3.8%$, $36.0{\pm}4.2%$, respectively. These result was significantly increased compare to the control.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.33-38
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• 2013

A study was carried out on the effect of particle size (mean diameter) on magnesium dust explosion. Experimental investigations were conducted in a 20-L explosion sphere, using 10 kJ chemical ignitors. Explosion tests were performed with three different dusts having mean diameter (38, 142, $567{\mu}m$) and the dust concentrations were up to $2250g/m^3$. The lower explosion limits(LEL) of magnesium dusts were about $30g/m^3$ at $38{\mu}m$ and $40g/m^3$ at $142{\mu}m$. LEL tended to increase with particle size and this means that the explosion probability of magnesium dust decreased with increase of particle size. The maximum explosion presssure ($P_m$) and $K_{st}$ (Explosion index) decreased with the increase of particle size. For magnesium powder of $567{\mu}m$, however, the explosive properties were not observed in the 5 kJ ignition energy.

• Membrane Journal
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• v.16 no.4
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• pp.259-267
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• 2006

The critical breakthrough pressure through both porous PVDF (polyvinylidenefluoride) and PTFE (poly-tetrafluoroethylene) was measured using pure water, $0.1M{\sim}4.0M$ NaOH aqueous solutions and $0.1M{\sim}3.0M\;NaHSO_3$ aqueous solutions. The critical breakthrough pressure through PTFE was observed to be higher than that through PVDF membrane at the same pore size. The critical breakthrough pressure decreased as the molar concentration of NaOH increased up to 1.0 M reaching the minimum and then increased further after 1.0 M NaOH up to 4.0 M NaOH. On the other hand, the critical breakthrough pressure measured using $NaHSO_3$ aqueous solutions was decreased with increasing the concentration of $NaHSO_3$. The critical breakthrough pressure could be well interpreted with Cantor's equation.

• Journal of applied mathematics & informatics
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• v.3 no.1
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• pp.101-115
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• 1996

In this paper we extend the best choice of subsample size m in the 2-stage sampling which suggested by Mohammad(1986) to the 3-stage sampling in cases of known and of unknown cost and variance ratio. We find the subsample size m.k which ensures more than the relative efficiency 90% Also we see that the choice of 3-stage subsample size depends on the design parameters using in 2-stage sampling.

• Applied Microscopy
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• v.28 no.4
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• pp.465-475
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• 1998

The cryoprotection, section retrieval and embedding methods were studied for the preservation of ultrastructure of ultracryomicrosections in immunoelectron microscopy. The results obtained were as follows. 1. The cryoprotection of ultrastructure with a mixture containing 1.7 M sucrose and 15% polyvinylpyrrolidone was better than that with 2.3 M sucrose. The stretching caused by surface tension and the electron lucent holes decreased more in the cryosections infused with 2.3 M sucrose than in those with the mixture. 2. The difference between section retrieval solutions in cases of cryoprotection with 2.3 M sucrose was that the destructive .effects such as electron lucent holes and stretching between myofribrils were less in a mixture containing 1% methylcellulose and 2.3 M sucrose than in 2.3 M sucrose. The difference was obscure in the mixture containing 1.7 M sucrose and 15% PVP, but the destructive effects were slightly less in a mixture containing 1% mthylcellulose and 2.3 M sucrose than in 2.3 M sucrose or 1% methylcellulose. 3. The embedding of cryosection on drying with 2% PVA or 2% methylcellulose exhibited some protective effect during observation with transmission electron microscope, but made the ultrastructure more obscure. 4. Mitochondrial membrane and cristae and myofilaments were well delinated in sections infused with 2.3 M sucrose and retrieved with 1% methylcellulose and 2.3 M sucrose. In summary, it is suggested that the cryoprotection with 2.3 M sucrose and section retrieval with a mixture containing 1% methylcellulose and 2.3 M sucrose are good for the ultrastructure of cryosections.

• Journal of Environmental Health Sciences
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• v.33 no.6
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• pp.506-512
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• 2007

This study was conducted to describe the exposure levels of welding fumes by the type of manufacturers, work process, welding type and the size of manufacturers, and to find out the trend of chronological changes of airborne welding fume levels. The subjects of this study were 509 manufacturers, consisting of 11 types of manufacturers, 3 work processes, 7 welding types, in Busan from January, 1997 to December, 2005. Airborne concentration of welding fume was determined by manual of National Institute for Occupational Safety and Health (NIOSH), and the data were analyzed by using SPSS 10.0 for Windows program. The mean concentration of airborne welding fume in all manufacturers was $1.29\;mg/m^3$ (Range: $0.01{\sim}3.00\;mg/m^3)$. The level of welding fume was the highest, as $1.96\;mg/m^3$, for manufactures of motor vehicles, trailers and semi-trailers, which was lower than $5.0\;mg/m^3$ of 8 hr-TWA in Korean permissible exposure limit for welding fume. There was a significant difference in the mean levels of welding fumes by work process, showing the highest in welding workshop ($1.39\;mg/m^3$), followed by pipeline welding workshop ($1.26\;mg/m^3$) and engineering workshop ($1.20\;mg/m^3$). Among welding types, the mean level of welding fume was the highest in the type of $CO_2$ & arc welding, as $1.46\;mg/m^3$, followed by $CO_2$ welding ($1.40\;mg/m^3$), shielded metal arc welding ($1.31\;mg/m^3$), spot welding ($1.27\;mg/m^3$), and so on. The highest mean level of welding fume was $1.58\;mg/m^3$ in work process of pipe line welding workshop for the manufacturers of basic iron and steel, and $2.27\;mg/m^3$ in the type of arc welding for the manufactures building ship and boats. By the size of manufacturers, the mean concentration of welding fume for manufactures in small scale with less than 50 workers was the highest as $1.45\;mg/m^3$ (Range: $0.07{\sim}3.00\;mg/m^3)$. The mean level of welding fume was the highest as $1.39\;mg/m^3$ both in 1997 and in 2005, showing a trend of fluctuating periodically within a range of $1.10{\sim}1.39\;mg/m^3$. The above results suggested that more effective control program for work environment producing welding fumes should be developed and applied since there were significant variations in welding fume levels by the type of manufacturers, work processes, welding types, the size of manufactures, and by year.