• 산업기술연구
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• 제24권B호
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• pp.171-176
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• 2004

The effects of agitation and aeration for exopolysaccharide(EPS) production through batch cultivation of an Enterobacter sp. isolated from the composter were investigated. During the EPS fermentation under conditions of constant agitation speed from 200 to 900 rpm and constant aeration rate of 0.5-2.5 vvm, the low yields of EPS(4.8-5.2g/L) was observed as the viscosity increase of culture broth. With the stepwise increases in agitation speed and aeration rate, the EPS production and the viscosity of EPS were increased 1.3~1.4 times and 2.3~3.6 times higher than those of the fixed conditions, respectively. Therefore, these stepwise increases were considered as the key operating parameters for enhancing EPS production. The max. EPS(6.8g/L) and viscosity(14,000cp) were obtained when the agitation speed was increased from 300 to 900 rpm for 54hrs at 1.5 vvm.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.725-728
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• 2000

The effects of agitation rate and agitation time on the synthesis of sphingosome were studied. As increase in the agitation rates 4,000, 6,000, 8,000, 10,000 and 12,000 rpm the viscosity of sphingosome were decreased. The most sufficient agitation rate was 8,000rpm for which micell viscosity and stability. The effect of agitation time on the sphingosome viscosity and stability was investigated by changing the agitation times 2, 4, 6, 8 and 10 minute at 8,000rpm. 4 minute was the most sufficient for the viscosity and stability. The sphingolipid activity of cutaneous wound healing in impaired mice was examined. As a result, we could prove that phytosphingosine-HCl medically worked on wound healing well. For the phytosphingosine-HCl, it was found that the experimentally determined medical action more effective than that of tetra-acetylphytosphingosine.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2002년도 생물공학의 동향 (X)
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• pp.192-195
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• 2002

Effect of aeration rate and agitation speed on cell growth and the production of heteropolysaccharide-7 (PS-7) by Beijerinckia indica was investigated. Aeration rate and agitation speed in a 7L bioreactor ranged from 0.5 to 1.5 vvm and from 300 to 500 rpm, respectively. Higher agitation speed with an aeration rate of 0.5 vvm in the bioreactor resulted in maintenance of higher concentration of dissolved oxygen in the medium, which enhanced the production of PS-7. In this study with a 7L bioreactor, maximal production of PS-7 was 11.0 g/L and its conversion rate from 2% (w/v) glucose was 0.55 when the aeration rate and agitation speed were 1.0 vvm and 500 rpm, respectively. Proper aeration rate and agitation speed might enhance the production of PS-7 as well as reduce the time to reach maximal production.

• 자원리싸이클링
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• 제27권1호
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• pp.45-54
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• 2018

플라이애시의 부유선별 과정에서 교반속도와 공기주입량과 같은 기계적 요소 변화에 따른 영향을 알아보고자 본 연구를 실시하였다. 본 연구에서는 미연탄소 함량이 약 3.4 ~ 3.7% 수준인 화력발전소 플라이애시를 사용하였다. 대표적인 부유선별의 선별 요소인 pH, 교반속도, 포수제 첨가량, 기포제 첨가량 변화에 따른 영향을 살펴보았을 때, Safflower oil을 포수제로 사용하여 첨가량을 800 g/ton, pH 7, 교반속도 1,200 rpm, 기포제 첨가량이 400 g/ton였을 때, 미연탄소 회수율과 미연탄소 함량이 각각 63%, 34%로 나타났다. 이 때 부상물 SEM/EDS 분석을 통해 알아본 결과, 구형의 플라이애시 미립자가 미연탄소 내에 고용되거나, 광액 내에 가라앉지 못하고 기포와 함께 부유함으로써 미연탄소의 함량을 낮추는 것으로 나타났다. 교반속도와 공기주입량과 같은 기계적 요소를 변화시킨 실험에서는 공기주입량 8L/min, 교반 속도 900 rpm에서 미연탄소 회수율 74%, 미연탄소 함량 67%인 것으로 나타났다. 이는 낮은 교반속도와 추가 공기주입으로 인하여 광액 내 와류의 강도가 낮아져, 미립의 플라이애시 입자가 미연탄소와 함께 부유되는 현상을 방지됨으로써, 미연탄소 회수율과 미연탄소 함량이 향상된 것으로 나타났다. 또한, 교반속도와 공기주입량을 각각 800 rpm, 6 L/min으로 설정하였을 때 미연탄소 회수율과 미연탄소 탄소함량이 각각 80%, 70%로 향상되어 가장 우수한 것으로 나타났다.

• 한국결정성장학회지
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• 제9권2호
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• pp.191-196
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• 1999

수열합성법을 이용한 $\alpha$-$SiO_2$ 단결정 분말 제조시 교반의 추가와 승온속도의 변화가 입자의 결정성, 입도분포 및 평균입경에 미치는 영향을 조사하였다. KOH를 광화제로 사용하였으며, $350^{\circ}C$에서 3시간 동안 반응을 시켜 평균입자 크기가 1~3.2$\mu\textrm{m}$인 결정 분말을 제조하였다. 실험결과 반응초기부터 교반을 한 경우에는 교반속도가 증가함에 따라 평균입경이 감소했으나, 결정성은 나빠지다가 150r/min 이상에서는 다시 좋아졌다. 또한 반응 도중에 교반을 추가하면 반응초기부터 교반을 한 경우보다 입자의 크기가 커졌다. 그러나 교반속도를 일정하게 한 후 승온속도를 느리게 하면 입자의 크기가 작아졌다.

• Journal of Microbiology and Biotechnology
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• 제21권6호
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• pp.652-658
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• 2011

The growth kinetics of Streptomyces noursei NRRL 5126 was investigated under different aeration and agitation combinations in a 5.0 l stirred tank fermenter. Poly-${\varepsilon}$-lysine biosynthesis, cell mass formation, and glycerol utilization rates were affected markedly by both aeration and agitation. An agitation speed of 300 rpm and aeration rate at 2.0 vvm supported better yields of 1,622.81 mg/l with highest specific productivity of 15 mg/l.h. Fermentation kinetics performed under different aeration and agitation conditions showed poly- ${\varepsilon}$-lysine fermentation to be a growth-associated production. A constant DO at 40% in the growth phase and 20% in the production phase increased the poly-${\varepsilon}$-lysine yield as well as cell mass to their maximum values of 1,992.35 mg/l and 20.73 g/l, respectively. The oxygen transfer rate (OTR), oxygen utilization rate (OUR), and specific oxygen uptake rates ($qO_2$) in the fermentation broth increased in the growth phase and remained unchanged in the stationary phase.

• Journal of Microbiology and Biotechnology
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• 제3권4호
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• pp.292-297
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• 1993

Aspergillus niger No. PFST-38 was grown on complex media in 30L agitated fermentors at various aeration rates and stirrer speeds. We could correlate the mixing time as a function of the Reynolds number and the apparent viscosity, as follows. ${\theta}_M=2.95\;\NRe^{-0.52},\;{\theta}_M=1.88\;{\eta_a}^{0.57}$ Also, the effects of the apparent viscosity (${\theta}_a$), the impeller rotational speed (N), the air flow rate ($V_s$), and the mixing time (${\theta}_M$) on the oxygen transfer coefficient, $K_L a$ were determined experimentally, and equated as follows. $K_La=12.04N^{0.88}Vs^{0.71}{n_a}^{-0.83},\;K_La=30.2N^{0.88}Vs^{0.71}{\theta_M}^{-1.45}$ $K_La$ increased as the agitation speed and the air flow rate increased. The rate of $K_La$ increase was dependent more on the rotational speed of impeller than on the air flow rate. The glucoamylase production increased with the increase of the agitation speed upto at 500 rpm and increased with the increase of air flow rate upto at 1.0 vvm. The values calculated from the above equation confirmed that the experimental maximum production of glucoamylase was achieved when the $K_La$ and the apparent viscosity of the broth were $260\;hr^{-1}$ and 1800 cps, respectively.

• KSBB Journal
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• 제16권3호
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• pp.307-313
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• 2001

The effects of agitaion and aeration on mycelial growth, exo-polysaccharide (EPS) production, and substrate consumption upon the submerged cultivation of G. lucidum were investigated, and the batch kinetics of the EPS fermentation of G. lucidum were interpreted as function of agitation speed and aeration rate. In a 2.6 L jar fermenter system, the optimum agitation speed and aeration rate for EPS production were determined to be 400 rpm and 1.0 vvm, respectively. The maximum production of EPS obtained was 15 g/L. The logistic model for mycelial growth fitted the experimental data better than that determined by the Monod and the two-thirds power models. The Luedeking-Piret equation adequately modelled the kinetic data obtained for product and substrate.

• 한국표면공학회지
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• 제27권2호
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• pp.109-117
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• 1994

Effect of ultrasonic agitation on the contact properties was studied in Ni electroless plating and Pd activation. P-type Si bare wafers were used as substrate and DMAB was used as reducing agent due to its good electrical properties, solderability and compatibility to substrate. In activation, high density Pd nuclei of small size were formed during ultra-sonic agitation compared to that of no stirring. In electroless plating, the plating rate was enhanced by 30∼90% by using ultrasonic agitation. In elecrtoless plating, inhibitor is the most effective additives in ultrasonic agitation. In this experi-ment, thiourea was used as inhibitor. The less the amount of the inhibitor, the more ultrasonic agitation efficiency. It is confirmed by SEM that Ni-B films formed by ultrasonic were coarser, less porous, and denser than those of no stirring. In ultrasonic agitation, boron content of the films was more than those of no stirring. In this case, the more DMAB concentration, the higher the temperature, the less pH, the more boron content. Resistivity of the films formed by ultrasonic agitation was higher than that of no strirring. As the content of boron was increased, the resistivity of the films was increased exponentially.

• 한국환경과학회지
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• 제10권1호
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• pp.65-71
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• 2001

HRP(high rate pond) which had kept the manufactured clay of 3cm-thickness as benthic clay in reactor and the 6 flat-blade turbine as impeller for agitation was named HRASP(high rate algae stabilization pond). And the experiment for treatment of artificial synthesis wastewater containing COD :300mg/$\ell$, NH$_3$-N : 300mg/$\ell$, T-P : 9mg/$\ell$ as nutrients was been performed successfully. This reactor was been operated under conditions : 24hrs.-irradiation and water temperature, $25^{\circ}C$ and pH 7 and agitation velocity, 15, 30, 45rpm and the effect of agitation velocity on algal bioaccumulation of nutrients was been studied with view point of fluid dynamics. The next followings could be obtained as results. 1. The agitation with a turbine impeller blade in HRASP makes clay particle indicate superior suspension effect by means of forming of excellent curl/shear flow in reactor. 2. The excessive suspension of clay particle which is created at 45rpm as rotation velocity of impeller blade of turbine disturbs the light penetration and algal photosynthesis reaction. 3. Efficiencies for removal of nutrients come out as COD : 93.9%~94.3%, ($NH_3-N + NO_3-N$) : 81.9%~99.0%, T-P : 46.8%~53.6%. 4. Kuo values of $K_1$for algal growth come out seperately as 15rpm : $1.876{\times}10^{-2}, 30rpm : 4.618{\times}10^{-3}$. 5. Kuo values of $K_2$for removal of N, P come out seperately as 15rpm : $8.403{\times}10^{-1}$ and $1.397{\times}10^{-1}$, 30rpm : $4.823{\times}10^{-1} and 2.052{\times}10^{-1}$. 6. It can be guessed easily that the excessive agitation can inhibit the algal and bacterial symbiotic reaction if it is considered that micro organism\` sense to preservation of life is relied on natural function of metabolism. Therefore the studies for this matter should be followed continuously.