• Bulletin of the Korean Chemical Society
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• v.16 no.9
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• pp.835-839
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• 1995

Mer,trans-Re(≡NC6H5)(PPh3)2Cl3, Ⅰ, reacted with trimethylphosphine to give a mixture of two stereoisomers, mer,trans-Re(≡NC6H5)(PMe3)2Cl3,Ⅱ, and fac,cis-Re(≡NC6H5)(PMe3)2Cl3, Ⅲ. These compounds could also be prepared from the reaction of Re(≡NC6H5)(PMe3)(PPh3)Cl3 with trimethylphosphine. In both reactions the mer,trans-isomer is a major product. The products have been characterized by NMR, elemental analysis, and X-ray crystallography. Crystal data for Ⅱ: monoclinic space group P21, a=10.053(1) Å, b=10.844(1) Å, c=10.058(2) Å, β=113.45(2)°, Z=2, R(wR2)=0.0348 (0.0894). Crystal data for Ⅲ: monoclinic space group P21/n, a=7.183(2) Å, b=16.983(4) Å, c=15.543(4) Å, β=90.38(2)°, Z=4, R(wR2)=0.0603 (0.1484).

• Korean Journal of Agricultural Science
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• v.15 no.2
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• pp.143-152
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• 1988

This study was conducted to obtain basic data which affected engine performance of the power tiller being widely used in the rural area. Among the various factors affected engine performance, only flywheel weight was considered as the major factor in this study. Fuel consumption ratio, motoring loss, torque, vibration and mechanical efficiency of the engine tested were measured and analyzed on the four levels of flywheel weight (32.2, 29.7, 26.4, 24.2 kg). The results obtained were as follows: 1. The maximum output of 6 and 7.5 kW engine was 7.43 kW and 7.85 kW respectively. When flywheel weight was reduced from 32.2 kg to 24.2 kg, output power of the engine was increased 0.27 kW in 6 kW engine and increased 0.39 kW in 7.5 kW engine. 2. The fuel consumption ratio was decreased from 300.8 to 296.8 g/kW-hr in 6 kW engine and decreased from 313.6 to 312.8 g/kW-hr in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. 3. The mechanical efficiencies of the engine was increased from 76.1 to 76.8% in 6 kW engine and increased from 76.7 to 77.0% in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. 4. When the flywheel weight was reduced from 32.2 kg to 24.2 kg, a tendency of a little decrease of vibration at X- and Z-axis in 6 kW engine and of a little increase of vibration at Y-axis in 6 kW engine and all directions in 7.5 kW engine was observed. 5. Motoring losses was decreased from 2.33 to l.76 kW in 6 kW engine and decreased from 2.46 to 1.84 kW in 7.5 kW engine when the flywheel weight was reduced from 32.2 kg to 24.2 kg. From the above results and the flywheel weight calculated theoretically, it was recommendable that the flywheel weight should be reduced about 7 kg in 6 kW engine and about 10 kg in 7.5 kW engine, respectively.

• Korean Journal of Microbiology
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• v.40 no.1
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• pp.54-59
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• 2004

$\beta$-Glucan has been efficiently produced with higher yield by the optimization of liquid cultivation conditions. The optimal composition of medium for batch culture was 5% (w/v) of glucose as a carbon source, 0.5% (w/v) of yeast and 0.5% (w/v) of malt extract as a nitrogen source, 0.1% (w/v) of $KH_2PO_4$ and 0.05% (w/v) $MgSO_4{\cdot}7H_2O$, which had been the base medium for determination of other conditions. The set-up conditions are pH 5.0, $28^{\circ}C$, 1 vvm for aeration and 300 rpm for agitation. In order to minimize the inhibition effect of glucose on the initial growth of mycelia and to maximize the production of extracellular $\beta$-glucan, we have reduced the initial glucose feed to 4% and added 2nd feed at the point of 70 hr from the initial feed. The 2nd feed was composed of glucose 3%, yeast extract 0.1 % and malt extract 0.1 %. It improved the $\beta$-glucan yield upto 5.2 g/L in comparison with 2.8 g/L resulted from batch cultivation. Moreover, the serial treatment of a cell wall lytic enzyme and bromelain to the mycelia was effective for extraction of the cell wall bound $\beta$-glucan. The yield of $\beta$-glucan extraction by the enzyme treatment was 3.5 g/L, which was almost 4 times higher than that by hot-water extraction.

• Microbiology and Biotechnology Letters
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• v.21 no.5
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• pp.435-439
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• 1993

For the overproduction of glutathione, Candida sp. mutant was isolated by the treatment with U.V. light. The highest glutathione production of Candida sp. mutant was obtained after shaking culture for 48 hours in the cullture medium containing glucose 1.5%(w/v), yeast extract 4.0% (w/v), KH2PO4 0.04%(w/v), biotin 5 ng/ml, and L-cysteine 0.04%(w/v). The optimal pH and temperature for the glutathione production were pH 6.0 and 25C, respectively.

• Journal of environmental and Sanitary engineering
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• v.16 no.4
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• pp.62-68
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• 2001

The advantages of hydrogen peroxide dissolution method were no discharge of noxious matter when dissolution of iron wire which used as the center supporter, reactions occur in room temperature and easy to recover dissolved iron. This study was aimed at gathering the basic data of iron wire dissolution- recovery process and proposes the reaction condition of iron wire dissolution- recovery process rind the factors influencing those reactions. The results were as follows : 1 . Hydrogen peroxide dissolution method used hydrochloric acid as the catalyst. 1. In the dissolution of iron wire(1.668 g), the condition of reaction was E1702(30 ml), HCI(20 ml) and $H_2O$(200 ml) ; time of the reaction was 18 min. P.W.(Piece weight) was 7.75 mg, and C.R. was $2.34{\;}{\Omega}$ 2. In the dissolution of iron wire(1.529 g), the condition of reaction was H7O2(30 ml), HCI(20 ml) and $H_2O$(200 ml), time of the reaction was 21 min., P.W.(Piece weight) was 7.73 mg, and C.R. was $2.35{\;}{\Omega}$. Hydrogen peroxide dissolution method used sulfuric acid as the catalyst. 1. In the dissolution of iron wire(0.834 g), the condition of reaction was $H_2O$(65 ml), $H_2SO_4$(5 ml) and 1702(5 ml) ; time of the reaction was 5 min.30 sec, P.W.(Piece weight) was 7.74 mg, and C.R. was $2.33{\;}{\Omega}$ 2. In the dissolution of iron wire(1.112 g), the condition of reaction was $H_2O$(65 ml), $H_2SO_4$(5 ml) and $H_2O_2$(5 ml) ; time of the reaction was 4 min.30 sec, P.W.(Piece weight) was 7.75 mg, and C.R. was $2.33{\;}{\Omega}$. Hydrogen peroxide dissolution method used hydrochloric acid and sulfuric acid as the catalyst confirmed a clean technology, because there were not occurred a pollutant discharged in the existing method.

• Asian-Australasian Journal of Animal Sciences
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• v.16 no.12
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• pp.1743-1748
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• 2003

The effect of pH on the fermentation characteristics and the formation of cis-9, trans-11 conjugated linoleic acid (CLA) and trans-11 octadecenoic acid by mixed ruminal bacteria was examined in vitro when incubated with linseed or rapeseed. Concentrate (1%, w/v) with ground linseed (0.6%, w/v) or rapeseed (0.5%, w/v) was added to 600 ml mixed solution of strained rumen fluid with artificial saliva (1:1, v/v), and was incubated anaerobically for 12 h at $39^{\circ}C$. The pH of culture solution was maintained at level close to 4.5, 5.3, 6.1 and 6.9 with 30% $H_2SO_4$ or 30% NaOH solution. pH increment resulted in increases of ammonia and total volatile fatty acid (VFA) concentration in culture solutions containing both oilseeds. Fermentation did not proceeded at pH 4.5. Molar proportion of acetate decreased but that of propionate increased as pH increased when incubated with oilseeds. While the hydrogenating process was very slow at the pH range of 4.5 to 5.3, rapid hydrogenation was found from the culture solutions of pH 6.1 and 6.9 when incubated with linseed or rapeseed. As pH in culture solution of linseed or rapeseed increases proportions of oleic acid (cis-9 $C_{18:1}$) and trans-11 octadecenoic acid increased but those of linoleic acid and linolenic acid decreased. The CLA proportion increased with pH in culture solution containing rapeseed but CLA was mostly not detected from the incubation of linseed.

• KSBB Journal
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• v.14 no.1
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• pp.103-108
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• 1999

A bacterium having strong fibrinolytic activity, S7-16 strain, was isolated from soil. The isolated bacterium was identified and named as Bacillus sp. S7-16. The optimal composition of the medium for the production of fibrinolytic enzyme by Bacillus sp. S7-16 was 0.5%(w/v) polypeptone, 0.5%(w/v) yeast extract, 0.3%(w/v) NaCl, 0.1% (w/v) $KH_2PO_4,\;0.3%(w/v)\;K_2PHO_4,\;and\;0.01%(w/v)\;MgSO_4{\cdot}7H_2O$. The optimal temperature and initial pH of the medium for the production of the enzyme were $35^{\circ}C$ and 7.0, respectively. The maximum production of the fibrinolytic enzyme was obtained after 24 hours of the incubation. Under the above conditions, the culture supernatant had strong fibrinolytic activity. Within pH4~11, the crude fibrinolytic enzyme was stable. The enzyme was stable up to $50^{\circ}C$. The optimum pH and temperature for the enzyme activity were around 7.5 and $40^{\circ}C$, respectively.

• Journal of electromagnetic engineering and science
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• v.15 no.1
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• pp.59-61
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• 2015

A wideband H-band detector operating near 300 GHz has been developed based on SiGe HBT technology. The detector consists of an on-chip antenna and a HBT differential pair for square-law detection. It showed responsivity of more than 1,700 V/W and noise equivalent power (NEP) smaller than $180pW/Hz^{0.5}$ for the measured frequency range of 250-350 GHz. The maximum responsivity and the minimum NEP were 5,155 V/W and $57pW/Hz^{0.5}$, respectively; both were obtained at 330 GHz with DC power dissipation at 9.1 W.

• Journal of the Korean Chemical Society
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• v.52 no.2
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• pp.164-168
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• 2008

CaWO4 crystals were synthesized by a microemulsion method. Various sizes and shapes of CaWO4 were obtained by changing the molar ratio (w) of H2O to CTAB. At w=5 and 10, oval CaWO4 crystals with length of 100 nm and 500 nm were obtained, respectively. At w=20, rod-like CaWO4 crystal with length of 1 μm was obtained. The sphere CaWO4 crystal with length of about 2~3 μm was obtained at w=30. The CaWO4 crystal morphology changes from oval to sphere via a rod by aggregation with increasing the molar ratio of H2O to CTAB.

• Korean Journal of Food Science and Technology
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• v.40 no.4
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• pp.424-429
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• 2008

To investigate the acid tolerance characteristics of the acid-resistant mutant, Leuconostoc paramesenteroides P-200, as a kimchi starter, this study examine proton permeability, ATPase activity, glycolysis activity, $Mg^{2+}$ release, and membrane fatty acid composition, and compared the data to that of its wild-type, L. paramesenteroides LP-W. In the proton permeability experiment, the LP-W and P-200 strains' average maximum half-time $(t_{1/2})$ values for pH equilibration through the cell membrane were approximately 5.7 and 9.3 min in 150mM KCl solution, and 4.2 and 8.3 min in 3% NaCl solution, respectively. Their values and pH levels for maximal specific ATPase activity showed that P-200 had greater activity than LPW. And the results of pH-dependent glycolysis activity showed that P-200 had greater activity than LP-W. Furthermore, after 2 hr at pH 4.0, LP-W and P-200 had percent magnesium release values of approximately 12% and 34%, respectively. A comparison of their membrane fatty acid compositions indicated that C18 and cyclo-C19 were the major different fatty acids between the two strains, and their contents of C18 and cyclo-C19 were 2.5% and not detected, respectively, in LP-W, and 6.4% and 11.4%, respectively, in P-200. These results indicate that the P-200 strain has significantly improved acid tolerance as compared to its wild type, LP-W.