• Korean Journal of Microbiology
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• v.36 no.2
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• pp.79-83
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• 2000

Activated sludge samples were collected from a municipal sewage treatment plant and used for enrichment of microbial consortia with aniline as the sole carbon and nitrogen source. Threc aniline-degrading bacteria were obtained lrom microbial consortia and an isolate which has excellent aniline degradability was selected for this study. The isolate was Gram-negative, and identified and designated as Delfha sp. JK-2 on the basis of various physiological and biochemical tests. 10 mM aniline was completely degraded within 24 hours after inoculation of the culture. Ammonium ion was liberated in the medium transiently during the incubation and disappeared when aniline was completely degraded. Addition of glucose as a supplementary source to aniline minimal media showed significant decrease in aniline degradat~on rate for the strain Effective degradation of aniline was achieved by the addition of 0.5% nitrate as a nitrogen source, and resulted in approximately 80% higher aniline degradation compared to the absence of nitrate. Phylogenetic analysis based on 16s [DNA sequence revealed that the strain was closely related to De@ia acidovorans, with 96% overall similarity. The 16s [DNA sequence of JK-2 was also found to be closely related to those of six other clonal types, including Acidovoru, Aquaspirillum. Xylophilus, Variovorm, and Rhodofernr.

• Korean Journal of Plant Tissue Culture
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• v.27 no.3
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• pp.203-211
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• 2000

In this study to produce large-scale scopolamine we were examined in the tumor calli of Datura metel L. induced by Agrobacterium tumefaciens $Ery{101}$. The growth and scopolamine contents of tumor calli were higher under light condition than in dark. The optimum condition of growth and scopolamine production were fluence rate of 16 $\mu$mol $m^{-2}s^{-1}$, spectra of red light region and 16 hour light periods on 50 mL SH liquid medium in 4 weeks culture. To increase of the scopolamine contents in tumor calli, the optimum concentration of nitrogen source were 1.8 mM NH$_4$+ and 40 mM NO$_3$. The optimum elicitor concentration for production of scopolamine were 10 mg/L chitosan and 15 mg/L yeast extract. The effect of precursors were good at the concentration of 0.2 mM tropine and 0.3 mM tropic acid, respectively. In order to increase of growth and scopolamine contents. we induced mutant from Datura metel L. tumor callus. Mutants of tumor calli were obtained by 3 Krad, 4 Krad and 6 Krad of ${60}^Cor-ray$. Among them, 3 Krad tumor callus was excellent on the growth and teratoma induction. The 4 Krad tumor callus was negligible for both growth and teratoma induction. But the 6 Krad tumor callus was the best in growth and teratoma induction. The formation of the mutant calli can be enhanced through hormonal combination of 1 mg/L 2,4-dichlorophenoxyacetic acid and 0.5 mg/L benzyladenine. We carry out selection mutant tumor calli for high content tropane alkaloid and suspension cultures for scopolamine production.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.3
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• pp.177-183
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• 2004

The discharge of waste nutrient solution from greenhouse to natural ecosystem leads to the accumulation of excess nutrients that results in contamination or eutrophication. There is a need to recycle the waste nutrient solution in order to prevent the environmental hazards. The amount and kind of nutrients in waste nutrient solution might be enough to grow photosynthetic microorganisms. Hence in the present study, we examined the growth and mass cultivation of cyanobacteria in the waste nutrient solution with an objective of removing N and P and concomitantly, its mass cultivation. Four photosynthetic filamentous cyanobacteria (Anabaena HA101, HA701 and Nostoc HN601, HN701) isolated from composts and soils of the Chungnam province were used as culture strains. Among the isolates, Nostoc HN601 performed faster growth rate and higher N and P uptake in the BG-II ($NO_3{^-}$) medium when compared to those of other cyanobacterial strains. Finally, the selected isolate was tested under optimum conditions (airflow at the rate of $1L\;min^{-1}$. in 15 L reactor, initial pH 8) in waste nutrient solution from tomato hydroponic in green house condition. Results showed to remove 100% phosphate from the waste nutrient solution in the tomato hydroponics recorded over a period of 7 days. The growth rate of Nostoc HN601 was $16mg\;Chl-a\;L^{-1}$ in the waste nutrient solution from tomato hydroponics with optimum condition, whereas growth rate of Nostoc HN601 was only $9.8mg\;Chl-a\;L^{-1}$ in BG-11 media. Nitrogen fixing capacity of Nostoc HN601 was $20.9nmol\;C_2H_4\;mg^{-1}\;Chl-a\;h^{-1}$ in N-free BG-11. The total nitrogen and total phosphate concentration of Nostoc HN601 were 63.3 mg N gram dry weight $(GDW)^{-1}$ and $19.1mg\;P\;GDW^{-1}$ respectively. Collectively, cyanobacterial mass production using waste nutrient solution under green house condition might be suitable for recycling and cleaning of waste nutrient solution from hydroponic culture system. Biomass of cyanobacteria, cultivated in waste nutrient solution, could be used as biofertilizer.

• Korean Journal of Food Science and Technology
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• v.36 no.6
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• pp.893-899
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• 2004

Method for sample preparation and quantitative analysis of 19 permitted and non-permitted synthetic colors in foods was developed based on reversed-phase ion-pairing high performance liquid chromatography. For color extraction of samples, deionized water was added, and pH was appropriately adjusted with 1% ammonia water. Any undissolved matters were extracted with 50% ethanol or 70% methanol. Lipid in snacks was first removed using n-hexane with centrifugation, water was added to extract colors, followed by clean-up and concentration using Sep-Pak $C_{18}$ cartridge. Recovery efficiencies at known concentrations of 19 standard food colors spiked into foods were in 90.3-97.9% range far soft drink, 79.2-101.9% for candy, 84.1-103.4% for jelly, 86.4-100.8% for chewing gum, 83.5-103.4% for ice cream, and 78.5-95.6% for snack.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.467-475
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• 2015

The effects of replacement of wheat flour with laver, Pyropia yezoensis, on the bread making properties and quality characteristics of bread were evaluated. The poor baking performance which arose from dried laver addition could be compensated by using exogenous enzymes (Flavouzyme) and baking aids. Laver hydrolysate was prepared by hydrolyzing laver using Flavouzyme for 9 hrs at $50^{\circ}C$. Doughs made by addition of laver hydrolysate (8% dried laver substitution level) showed excellent baking properties. Moreover, with the addition of glucose oxidase and hydro colloidal HPMC, loaf volume and crumb grain were improved for doughs containing laver hydrolysate. Both of intermediate fermentation and final proof time for doughs containing laver hydrolysate was shorter than that for conventional dough.

• Journal of Mushroom
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• v.6 no.1
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• pp.27-31
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• 2008

The optimization of submerged culture conditions for mycelial growth and exopolysaccharide (EPS) production in an edible mushroom Tremella fuciformis were studied in shake flasks and bioreactors. The temperature of $28^{\circ}C$ and pH 8 in the beginning of fermentation in agitated flasks was the most efficient condition to obtain maximum mycelial biomass and EPS. The optimal medium constituents were as follows (g l-1): glucose 20, tryptone 2, $KH_2PO_4$ 0.46, $K_2HPO_4$ 1 and $MgSO_4H_2O$ 0.5. The fungus was cultivated under various agitation and aeration conditions in a 5L stirred-tank bioreactor. The maximum cell mass and EPS production were obtained at a relatively high agitation speed of 200 rpm and at an aeration rate of 2 vvm. The flow behavior of the fermentation broth was Newtonian and the maximum apparent viscosity (35 cP) was observed at a highly aerated condition (2 vvm). The EPS productivity in an airlift reactor was higher than that in the stirred-tank reactor. The EPS was protein-bound polysaccharides consisted of mainly mannose, xylose, and fructose. The molecular weights of EPS were determined to be $1.3{\sim}1.5{\times}10^6$.

• Journal of IKEEE
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• v.13 no.2
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• pp.126-131
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• 2009

To overcome short channel effects, wrap-around field effect transistors have drawn a great deal of attention for their superior electrostatic coupling between the channel and the surrounding gate electrode. In this paper, we introduce a bottom-up technique to fabricate a wrap-around field effect transistor using silicon nanowires as the conduction channel. Device fabrication was consisted mainly of electron-beam lithography, dielectrophoresis to accurately align the nanowires, and the formation of gate electrode using electrochemical deposition. The electrolyte for electrochemical deposition was made up of non-toxic organic-based solution and liquid nitrogen was used as a method of maintaining the shape of polymethyl methacrylate(PMMA) during the process of electrochemical deposition. Patterned PMMA can be used as a nano-template to produce wrap-around gate nano-structures.

• Clinical and Experimental Reproductive Medicine
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• v.23 no.1
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• pp.41-49
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• 1996

본 연구는 체외수정에 의해 생산된 생쥐 배반포기배를 vitrification 방법으로 동결보존하였을때 높은 생존율을 얻기 위한 적정조건을 검토하고자 실시하였다. 배반포기배를 생산하기 위하여, B6CBA F1 (C57BL/6, (표현불가)${\times}CBA/N$, (표현불가)) 계통의 생쥐 미수정란에 $1{\times}10^6$ spermatozoa/ml 농도의 정자로서 수정을 유도하였으며, 이후 $37^{\circ}C$, 5% $CO_2$배양기내에서 96시간동안 체외배양하였다. 배양 4일째의 배반포기배는 발달상태에 따라 early, middle 그리고 hatching blastocysts로 구분하였다. 본 실험에 사용된 동결보존액은 30% Ficoll과 0.5mol의 sucrose가 첨가된 mDPBS 용액에 40%의 ethylene glycol를 첨가한 EFS 40 (Zhu et al., 1993) 이었고, 수정란은 $25^{\circ}C$의 상온에서 먼저 20% ethylene glycol에 노출된 후 EFS 40 용액으로 옮겨 액체질소에 침지하는 2단계 동결법에 의해 동결보존되었으며, 급속융해하여 다음과 같은 결과를 얻었다. 1. 체외수정율과 배양 4일째 배반포기까지의 배발달율은 각각 89.4%와 86.1%였다. 2. 20% ethylene glycol에서 5분간 평형된 후 EFS 40 용액에 냉동보존된 후 융해된 난자의 생존율은 20% ethylene glycol에 0, 1, 3분간 평형된 난자의 생존율에 비해 유의하게 높았다. 3. 배반포기배를 20% ethylene glycol에서 5분간, EFS 40 용액에 1분간 차례로 노출한 다음 체와배양하였던 바, 배양 24시간째 생존율은 $82.9%{\sim}88.4%$ 였다. 본 연구 결과, 체외수정, 배양된 생쥐 배반포기배는 20% ethylene glycol과 EFS40에 대한 노출만으로는 난자의 생존성에 나쁜 영향을 미치지 않는 것으로 미루어 보아 배반포기배의 초자화 동결이 가능함을 시사하였다. 따라서 동결 융해 후 높은 생존율은 상온에서 난자를 2단계 즉, 20% ethylene glycol에 5분간 평형시킨 후 EFS 40 용액에 노출하여 1분내에 LN2에 직접 침지하는 간편한 동결방법으로 얻을 수 있었다.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.64-73
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• 2007

A Large thermal vacuum chamber (LTVC) for space environment simulation on large satellites was successfully developed and constructed by KARI (Korea Aerospace Research Institute) in Korea with a local company. This chamber has an effective diameter of 8 meters and depth of 10 meters, and is composed of vacuum system, thermal control system, and anti-vibration system. Temperature below $-190^{\circ}C$ is maintained over the thermal shroud wrapping a satellite under $3.7{\times}10^{-5}Pa$ ($5{\times}10^{-7}torr$) vacuum level, and optical test can be done in this chamber by seismic mass with $10^{-5}g_{rms}$ or lower vibration level. In addition, the shroud temperature can be increased up to $123^{\circ}C$ using halogen lamps. Chamber control program based on PLC (Programmable Logic Controller) could control this large thermal vacuum chamber automatically.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.1
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• pp.93-100
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• 2011

The thermal property of insulation material is essential in developing a high-temperature superconductor (HTS) power cable to be operated at around liquid-nitrogen temperature. Unlike metallic materials, nonmetallic materials have a high thermal resistance; therefore, accurate estimate of the heat flow is difficult in the case of nonmetallic materials. The aim of this study is to develop an instrument for precisely measuring the thermal conductivity of insulating materials over a temperature range of 30 K to approximately the room temperature by using a cryocooler. The details of the thermal-conductivity measurement system, including the design and fabrication processes, are described in this paper. In addition, the design optimization to minimize unavoidable heat leakage from room temperature is discussed.