• Journal of Biosystems Engineering
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• v.20 no.3
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• pp.250-261
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• 1995

This study has been performed to develop an agricultural waste incinerator to combust the rice hull originated from RPC with the typical disposal treatment capacity of 30kg/h and to test performance of the developed incinerator. Experimental results are summarized as following. 1. The optimum feed rate of rice hull of the incinerator is 30kg/h with air ratio of 1.5. 2. The contents of $SO_2$ in flue gas is maximum 18ppm(when rice hull feed rate was 20kg/h and air ratio of 1.5), minimum 7ppm(when rice hull feed rate was 30kg/h and air ratio of 1.5) and average 11ppm. So there is no environmental pollution problem for the incinerating treatment of rice hull of the RPC. 3. The temperature of water of heat exchanger are $53^{circ} C$ and $62^{circ} C$ with water flow rate $3{ell}/min$ and $1.5{ell}/min$ at the optimum combustion condition, respectively. 4. According to theoretical energy calculation, the energy from rice hull combustion may be amounted as much as 80%~190% of energy supplied by kerosene required by RPC.

• Resources Recycling
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• v.8 no.4
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• pp.39-44
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• 1999

Nightsoil and brewery sludges usually contain a high concentration of organic matters. A composting study using reactors was carried out for the recycle of brewery wastewater sludge and nightsoil treatment sludge, which have been landfilled. A good composting process was obtained with a sludge mixing ratio of 1:1 and injual pH had no effect on temperature increase related to microbial activity. The injtial C/N ratio at approximarely 15 decreased to 13 without the increase in pH.. It was found that agitation of one time a week provided the most effective composting process.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.600-604
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• 2003

This study pointed at isolation of bunker-C oil degrading bacteria and then estimation of it's degrading capability in environmental conditions. Degradation ratio of the excellent isolate was appeared to 40.5% and 44.7% when the oil was treated to 1% and 5%, respectively. The isolate was identified to Acinetobater calcoaceticus SEBCM. In pH test, high degrading effect was appeared to about 73% at pH 6 and pH 7, and low degrading ratio was 37% at pH 4. Its growth condition at temperature has not large variation in $15^{\circ}C\;{\sim}30^{\circ}C$, Quantity of nitrogen for it's good growth was ranged of $0.5\;g/L{\sim}2\;g/L$. As these results, we realized that this isolate have good activity when treated to $15\;{\sim}30^{\circ}C$ of temperature and $6{\sim}7$ of pH.

• Journal of Magnetics
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• v.5 no.1
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• pp.23-25
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• 2000

We have investigated the effects of Ar and$O_2$-ion milling on the exchange coupling field ($H_{ex}$) and coercive field ($H_c$) at the interfaces between substrates and NiO/NiFe films, to understand the exchange biasing mechanism. The $O_2$-ion milling was successfully performed by means of the electron cyclotron resonance (ECR) process. We found that the local roughness gradient of the NiO surface increased by $O_2$-ion milling. The ratio of $H_{ex}/H_c$ increased from 0.87 to 1.77, whereas $H_c$ decreased by almost a half as a results of the ion milling. The decrease in $H_c$could be interpreted as due to the refinement of magnetic domain size, which arose from the increase of the local roughness gradient of the NiO surface. The decrease in low $H_c$, and increase in $H_{ex}$ in NiO spin valves by ECR-ion milling are in the right direction far use in magnetoresistance (MR) heads.

• Journal of Surface Science and Engineering
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• v.31 no.2
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• pp.117-126
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• 1998

In this study, the residue remaining on the silicon wafer during the oxide overetching using $C_4F_8/H_2$ helicon were plasmas and effects of various cleaning and annealing methods on the removal of the remaining residue were investigated. The addition of 30%$H_2$ to the C4F8 plasma increased the C/F ratio and the thickness of the residue on the etched silicon surface. Most of the residuse on the etched surfaces colud be removed by the oxygen plasmsa cleaning followed by thermal annealing over $450^{\circ}C$. Hydrogen-coataining residue formed on the silicon by 70%$C_4F_8/30%H_2$ helicon plasmas was more easily removed than hydrogen-free residue formed residue formed by $C_4F_8$ helicon wear plasmas. However, damage remaining on the silicon surface overetched using 70%$C_4F_8/30%H_2$ helicon plasmas was intensive and the degree of reocvery duing the post-annealing was lower.

• Korean journal of applied entomology
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• v.41 no.1
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• pp.21-25
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• 2002

Longevities of Hemiptarsenus zilahisebessi, ectoparasitoid of Liriomyza trifolii (Burgess) larva. were 23.0, 16.9. and 12.7 days at 20, 25, and 30$^{\circ}C$, respectively. The adults copulated and laid eggs as soon as they emerged at 20$^{\circ}C$ and 30$^{\circ}C$. The total number of eggs laid and the daily oviposition rate were 82.3/3.6, 90.3/6.0, and 95.5/7.8 at the three different constant temperatures. The sex ratios were 0.37,0.43. and 0.43 at 20,25, and 30$^{\circ}C$. respectively. Female oviposited 1.4 eggs near parasitized host larva and the average distance between eggs of H. zilahisebessi andhost larva wre 0.92mm. The instrinsic increase rates(r$\sub$m/) of H. zilahisebessi were 0.12, 0.19 and 0.27, and net reproduction were 31.0, 40.2, and 40.8 at 20,25, and 30$^{\circ}C$, respectively. Female of H. zilahisebessi oviposited mainly on the 3rd larva and sex ratio was 0.42, wheras the ratio was declined to 0.1 on the 1st larva.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.3
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• pp.287-294
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• 1995

This study demonstrates the influence of environmental conditions, other than iron, on pyoverdin production by fluorescent Pseudomosonas. In slightly acidic pH conditions(pH 6), cell yield was reduced while the siderophore production per cell yield was increased. The optimum temperatures for the siderophore production and cell yield was $19^{\circ}C$ and $28^{\circ}C$ for 7NSK2 and $12^{\circ}C$ and $19^{\circ}C$ for ANP15. The carbon and nitrogen balance showed that at low C : N ratio of the growth medium (higher nitrogen concentration), both cell yield and siderophore production was reduced. Use of different carbon sources revealed that citrate as a carbon source facilitated iron uptake and resulted in a significant reduction in siderophore production. However, at the late exponential phase, the iron content in the cell biomass was not significantly different from those grown in glucose or succinate. From these results it can be suggested that the environmental factors other than iron may also influence siderophore production by fluorescent pseudomonas.

• Journal of Microbiology
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• v.43 no.1
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• pp.28-33
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• 2005

The purpose of this study was to develop a multipurpose incubator, without the gas cylinders (bottles) which are required for $H_2$ and $CO_2$ supplementation. In our bottle-free multipurpose incubator, the $H_2$ and $CO_2$ were generated by chemical reactions induced within the chamber. The reaction between sodium borohydride and acetic acid at a molar ratio of 1:1 was used to generate $H_2$, according to the following formula: $4NaBH_4+2CH_3COOH+7H_2O{\rightarrow} 2CH_3COONa+Na_2B_4O_7+16H_2$, whereas the other reaction, citric acid and sodium bicarbonate at a 1:1 molar ratio, was used to generate $CO_2$, according to the following formula: $C_6H_8O_7+3NaHCO_3{\rightarrow}Na_3(C_6H_5O_7)+3H_2O+3CO_2$. Five species of obligate anaerobic bacteria, one strain of capnophilic bacterium, and one strain of microaerophilic bacterium were successfully cultured in the presence of their respective suitable conditions, all of which were successfully generated by our bottle-free multipurpose incubator. We conclude that, due to its greater safety, versatility, and significantly lower operating costs, this bottle-free multipurpose incubator can be used for the production of fastidious bacterial cultures, and constitutes a favorable step above existing anaerobic incubators.

• Journal of Microbiology and Biotechnology
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• v.10 no.1
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• pp.69-74
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• 2000

The medium for erythritol production by Torula sp. in a 500-ml baffled flask was optimized to be 300 g/I sucrose, 10 g/I yeast extract, 3 g/I $KH_2PO_4$, and 10 mg/I $CuSO_4{\cdot}5H_2O{\;}at{\;}34^{\circ}C$ with initial pH of 5.5. Using this optimal medium, erythritol of 166 g/I was obtained after 140 h of cultivation, corresponding to 55.3% of the erythritol yield from sucrose with a productivity of 1.11 g/I/h. Optimal concentrations of carbbon and nitrogen sources in a fermentor were higher than that in a flask due to the higher oxygen supply of the fermentor. Employing the medium containing 300 g/I or 400 g/I sucrose for the determination of optimal C/N ratio, the C/N ratio was found to be more important than the nitrogen concentration for effective erythritol production, The optimal ratio of yeast extract to sucrose (g/g) was 20. The yield and productivity of erythritol were maximal in the medium containing 400 g/I sucrose and 20 g/I yeast extract. when dissolved oxygen in the culture was increased, the cell mass increased but the erythritol production was manimal in the range of 5 to 10% of dissolved oxygen. Under the optimal the rane of 5 to 10% of dissolved oxygen. Under the optimal culture condition of the fermentor, a final erythritol concentration of 200 gI was obtained after 120 h with a yield of 50% and the productivity was 1.67 g/I/h. The yield was the highest among erythritol-producting microorganisms

• Journal of Environmental Science International
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• v.11 no.4
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• pp.347-353
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• 2002

This study was conducted to investigate the characteristics of chloramination as a secondary disinfection in a drinking water distribution system. At the range from pH 6 to pH 8, monochloramine was predominant with a trace of dichloramine, and the free chlorine was detected after breakpoint. At $25^{\circ}C$, the breakpoints of pH 6, 7 and 8 appeared when the weight ratios of chlorine to ammonia nitrogen were 11:1, 9:1 and 10:1 respectively, and the peak points on the breakpoint curves at pH 6, 7 and 8 were in the Cl$_2$ / NH$_3$-N ratio of 9:1, 6:1 and 5:1 respectively. As pH increased from 6 to 8, maximum point of monochloramine on the breakpoint curve was moved from 7:1 to 5:1 in the weight ratio of chlorine to ammonia nitrogen. The maximum concentration of monochloramine was formed at the pH values of 7~8 and in the Cl$_2$ / NH$_3$-N ratio below 5:1. As the Cl$_2$/NH$_3$-N ratio increased and the pH lowered, chloramines decay proceeded at an increased rate, and residual chloramines lasted longer than the residual free chlorine. The monochloramine and the dichloramine were formed at pH 6, and then the dichloramine continued increasing with contact time.