• Microbiology and Biotechnology Letters
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• v.13 no.4
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• pp.397-402
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• 1985

The fermentation of various sugars by C. thermosaccharolyticum was examined under pH controlled, anaerobic condition. The kinetic model for Product formation at various sugars was the combination of growth and non-growth associated mode. In the utilization of a single sugar, glucose was the best carbon source for growth. The specific growth rate of glucose, xylose and cellobiose were 0.363 h$^{-1}$, 0.242 h$^{-1}$ and 0.144 h$^{-1}$ respectively. The production of ethanol from glucose showed a negatively growth associated mode, so the higher growth rate decreased the productivity of ethanol. The maximum concentrations of the produced ethanol were 2.42 g/l, 3.76 g/l, and 3.4 g/l on glucose, xylose, and cellobiose. No glucose was detected during cellobiose fermentation. Sequential utilization of sugars was observed in the mixtures of glucose, xylose and cellobiose. It preferred glucose, followed by xylose and then cellobiose. The presence of other sugars had little or no effect on the rate of another sugar utilization. Cell lysis at the end of fermentation occured more slowly in the mixtures of sugars than a single sugar.

• Microbiology and Biotechnology Letters
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• v.16 no.6
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• pp.494-498
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• 1988

The optimum conditions for glucoamylase production, and ethanol productivity of the transformant TSD-14 were investigated as compared with the parental strains. The properties of TSD-14 were comparatively similar to the donor S. diastaticus IFO 1046 as regards the conditions of glucoamylase production and ethanol productivity. The soluble starch was the most effective carbon source for the glucoamylase production. While inorganic nitrogen sources did not prompt cell growth and enzyme production, the organic nitrogen sources generally enhanced both cell growth and glucoamylase production. The metal salts such as FeSO$_4$, MgSO$_4$, MnCl$_2$, and NiSO$_4$were favorable to the enzyme production. And the optium temperature and initial pH for glucoamylase production were 3$0^{\circ}C$ and 5. The transformant TSD-14 produced 8.3%(v/v) ethanol from 15% sucrose medium, 4.8%(v/v) ethanol from 15% soluble starch medium, and 7.5%(v/v) ethanol from 15% liquefied potato starch medium. The corresponding fermentation efficiency were 84% , 45% and 70%, respectively.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.3
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• pp.191-196
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• 2017

Owing to the harmful environmental effects of HCFC and CFC refrigerants discovered in the late 20th century, the need for environmentally friendly refrigerants such as $CO_2$ in cooling systems has increased. Air-source $CO_2$ heat pumps that utilize ambient heat in cold winter are less efficient because of a higher evaporation temperature, and it is difficult to manufacture the components of the heat pump owing to a super critical pressure of over 130 bar. This research aims to overcome these disadvantages and improve energy efficiency by introducing a new lower-pressure $CO_2$ auto-cascade heat pump system. $CO_2$-R32 zeotropic refrigerants were considered for two-stage expansion and effective cooling heat exchanging system configurations of the new auto-cascade heat pump. The results indicated that the efficiency of the two-stage expansion system was higher than that of the original one-stage expansion system. Furthermore, the two-stage expansion system showed significant performance improvements when the two-stage expansion stage from highest pressure of 70bar, intermediate expansion pressure of 25bar, and final low pressure of 10bar is applied. The COP of the new two-stage auto-cascade system (2.332) was 43.15% higher than that of the present simple auto-cascade system (1.629). Refrigerants having an evaporation temperature of $-10^{\circ}C$ or lower can be obtained that can be easily evaporated in an evaporator even at a low temperature.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.90-102
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• 2017

In this study, various types of nutrient models were tested by using two tears's water quality data collected from the stormwater wetland in Korea. Based on results, most important factor influencing nitrogen removal was hydraulic loading rate, which indicates that surface area of wetland is more important than its volumetric capacity, and model proposed by WEF was found to give a least error between measured and calculated values. For the phosphorus, in case assuming a power relationship between rate constant and temperature, the best prediction result were obtained, but temperature was most sensitive parameter affecting phosphorus removal. In addition, denitrification was always a limiting step for the nitrogen removal in this particular wetland mostly due to the lack of carbon source and high dissolved oxygen concentration. In this paper, several alternatives to improve nitrogen removal, including proper arrangement and designation of wetland elements and use of floating plants or synthetic fiber mat to control oxygen level and to capture the algal particles were proposed and discussed.

• Journal of Wetlands Research
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• v.22 no.3
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• pp.171-177
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• 2020

To improve the nitrogen reduction capability of stormwater treatment systems subjected to intermittent saturation, organic materials are often added as filter media. However, these materials can be an additional source of organic carbon and increase the chemical oxygen demand (COD) in the outflow. In this study, different types of organic filter media were subjected to a batch leaching test to observe and quantify the release of COD. Results reveal that the initial pH of the tap water used for soaking which is 7.5-7.7 is conducive to the release of organics from the media to the leachate. The highest amount of COD released was observed in yard clippings and woodchip followed by compost and bark mulch. The leaching of organics also increased as the size of the media decreases due to higher surface area per volume. In addition, empirical regression analysis predicted that COD from these organic media will be exhausted from the material in 3-5 months to up to 26 months depending on the type of media. The results of this study can serve as a guide in estimating the potential release of COD in organic media in order to ensure their safe application in stormwater treatment facilities.

• The Korean Journal of Mycology
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• v.14 no.4
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• pp.257-263
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• 1986

So as to clarify the biodegradation mechanism of lignin, lignin biodegradability among four white-rot fungi, Pleurotus ostreatus 1,2,3, and Polyporus versicolor were compared each other by simple plate test method, so that P. ostreatus 2 and P. versicolor exhibited the most wide clear zone. And to investigate the degree of lignin depolymerization, they were grown in lignin­media where various carbohydrates were added, then that was analyzed through column chromato­graphy. In consequence, P. ostreatus 2 and 3 showed more excellent effect of lignin depolymerization among those 4 white-rot fungi, and also in culture media in which glucose, cellobiose and xylose were added. When culture filtrates of the same media were scanned at UV range, there were no peak at 280 nm in the culture filtrate of P. ostreatus 2 and 3 where glucose, cellobiose and xylose were added. At the same time, culture filtrate, in which lignin was only contained as a carbon source, showed browning in color, whereas culture media with glucose, cellobiose and xylose in addition to lignin became yellowish (that is, decolorization). From above results, it might be assumed that polymerization and browning of lignin were decreased and lignin biodegradability was increased, when grown in lignin media where various carbohydrates were added.

• Korean Journal of Materials Research
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• v.5 no.7
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• pp.775-780
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• 1995

Thin films of titanium nitride are formed using the tetrakis-dimethyl-amino-titanium (TDMAT(Ti[N($CH_3$)$_2$]$_4$)) under various conditions. The formation of TiN films has been obtained from the thermal decomposition of the Ti-precursor and the gas phase reaction between TDMAT and ammonia(NH$_3$). The resistivity of the MOCVD film can be attributed to their impurity. Especially the curve fitting graph of XPS data is revealed that main impurities in the films as carbon and oxygen make various interstitial compounds which has influenced physical and electrical properties of the film. In the contact hole with the aspect ratio of 3:1 and the diameter of 0.5${\mu}{\textrm}{m}$, the SEM morphology shows that the step coverage is more decreased in the films formed y flowing ammonia additionally than the films formed by pyrolysis of TDMAT and the phenomenon is probably related with the activation energy.

• Korean Journal of Microbiology
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• v.50 no.3
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• pp.210-215
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• 2014

Pseudomonas nitroreducens TX1 was isolated from a rice field drainage in Taiwan. The bacterium is of special interest because of its capability to use a group of nonionic surfactants such as alkylphenol polyethoxylates even at high concentrations as a sole carbon source. In this study, a small cryptic circular plasmid, pTX1, was characterized from P. nitroreducens TX1. It is 2,286 bp in length with a GC content of 63.3% and harbors three open reading frames, $Rep_{pTX1}$ and functionally unidentified ORF1 and ORF2. The predicted $rep_{pTX1}$ gene product is homologous to Rep proteins of plasmids belonging to the pC194/pUB110 family, which is predominantly found in Gram-positive bacteria and is known to replicate by the rolling-circle mechanism. The copy number of pTX1 was estimated to be about 150 in each cell. Based on the genetic fingerprints and comparison with other plasmids, it is concluded that pTX1 replicates by a rolling circle mechanism which is rarely found for Pseudomonas plasmids.

• Korean Journal of Microbiology
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• v.50 no.1
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• pp.33-39
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• 2014

One hundred forty four bacterial colonies which were able to degrade crude oil were isolated from soil samples that were contaminated with oil in Daejeon area. Among them, one bacterial strain was selected for this study based on its emulsification activity, growth rate and surface tension activity, and this selected bacterial strain was identified as Pseudomonas sp. HN37 through physiological- biochemical tests and analysis of its 16S rRNA sequence. Pseudomonas sp. HN37 utilize the several aliphatic hydrocarbons, 3,5-dinitrosalicylic acid and 2,4-dichlorophooxyacetic acid as a sole carbon source. And this bacterial strain showed a high resistance to antibiotics such as ampicillin and chloramphenicol, as well as heavy metals such as Ba, Cr, Li and Mn. Also, it was found that the optimal pH and temperature for the cell growth, surface tension, and emulsification activity of Pseudomonas sp. HN37 were pH 6.0-9.0 and $30^{\circ}C$, respectively. The emulsification and surface tension activity was reached the maximum to 1% (V/V) crude oil and 1% (W/V) NaCl concentration. The surface tension of the culture broth was decreased from 62 to 27 dyne/cm after fifteen hours of inoculation in LB media.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.441-444
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• 2002

This study was targeted to develope a microbial consortium having high cellulase production. A filamentous fungus, strain FB01, isolated from a compost showed high ${\beta}-glucosidase$ activity especially. The strain FBOl was co-cultured with Trichoderma viride to enhance the productivity of ${\beta}-glucosidase$, changing inoculation time of one strain (FB01). The microbial consortium prepared showed the higher cellulytic enzyme production than T. viride well-known. The maximal enzyme production was obtained when the microbial consortium was cultured at $30^{\circ}C$ and pH 6.0 for 10days and the activities of CMCase, ${\beta}-glucosidase$, and avicelase were 2.0, 0.8, and 0.2 U/mL, respectively. These enzyme activities were 2, 4, and 2 times as high as those of CMCase, ${\beta}-glucosidase$, avicelase from T. viride, respectively, indicating that a synergistic interaction appeared between T viride and strain FB01. The serial subcultures by pH control increased ${\beta}-glucosidase$ production about 3.2 times. Also, enzyme production using rice-straw as a carbon source showed that the activities of CMCase, ${\beta}-glucosidase$, and avicelase were 3.69, 0.76, 0.17 U/mL, respectively, and ${\beta}-glucosidase$ activity was 1.5 times higher than that of T. viride. Consequently, microbial consortium showed the considerabely enhanced production of the cellullolytic enzymes, such as CMCase, ${\beta}-glucosidase$, and avicelase compared those of T. viride, and a favorable stability for the enzyme production even in the serial subcultures.