• 한국산업융합학회 논문집
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• 제11권1호
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• pp.19-26
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• 2008

The gas-liquid mass transfer volumetric coefficients in gas-liquid agitated vessels with wire gauge impellers were measured to be compared with those in vessels with disk turbine and paddle impellers. Also mass transfer volumetric coefficients for disk turbine, paddle impeller and wire gauge impeller in cylindrical agitated vessel was measured over a wide range of Reynolds number from turbulent flow to transition regions. The effect of geometries on $k_La$ is clarified experimentally. Mass transfer volumetric coefficients $k_La$ depends only on the power consumption ($P_{gv}+P_{av}$) per unit volume.

• 공업화학
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• 제24권6호
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• pp.650-655
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• 2013

본 연구에서는 Pd/C 촉매를 이용하여 무수말레인산(maleic anhydride) 수용액상에서 수소화 반응을 통해 호박산(succinic acid) 합성을 진행하였으며, 그에 따른 최적 공정 조건을 도출하고자 하였다. 반응 온도 및 반응시간에 따른 호박산 순도의 차이는 크지 않았으나 압력과 교반속도가 증가함에 따라 불순물의 생성이 줄고, 호박산의 순도가 증가함을 확인하였다. 실험 결과 본 수소화 반응에서는 압력과 교반속도가 기체-액체 간 물질전달저항을 감소시켜 반응속도를 증가시킬 수 있는 가장 중요한 변수임을 확인하였으며 이에 따라 압력과 교반속도에 대한 반응속도를 구하였다. 반응압력이 5 bar에서 10 bar로 2배 증가 시, 반응속도는 2.14배 증가하였으며 교반속도가 300 rpm에서 700 rpm으로 2배 증가 시, 반응속도는 2.36배 증가함을 확인할 수 있었다.

• 한국산업융합학회 논문집
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• 제14권2호
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• pp.73-78
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• 2011

Power consumption for wire gauge impeller in cylindrical agitated vessel was measured over a wide range of Reynolds number from laminar to turbulent flow regions. The power correlation were obtained agitation power input of WM4 at gassing condition in turbulent region, at gassing condition in transient region and at gassing condition in laminar region. Also the compared with effect of impeller diameter and blade width on agitation power input at gassing condition in turbulent region, at gassing condition in transient region and at gassing condition in laminar region.

• 공업화학
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• 제17권5호
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• pp.509-516
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• 2006

Rushton turbine, paddle and propeller 임펠러 등 표준적인 임펠러가 부착된 기-액-고 3상교반조에서 고-액간 물질이동계수 $k_L$를 측정하였다. 표준적인 임펠러들에 대한 부유화한계회전수 $N_{js}$는 임펠러 높이와 가스유속에 따라 변했다. 입자부유가 통기에 의존한 Rushton turbine 임펠러의 물질이동계수는 Pgv에만 상관하였다. Rushton turbine, paddle and propeller 임펠러에 대한 물질이동계수 $k_L$은 임펠러의 종류에 의하지 않고 임펠러 위치에 영향을 받았다.

• Journal of Microbiology and Biotechnology
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• 제10권3호
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• pp.367-374
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• 2000

The composition of dissolved gases and nutrients in a liquid medium were determined for establishment of the optimum conditions for in vitro culture of Helicobacter pylori. A microaerobic condition facored by the organism was prepared by adjusting the partial pressure of the gas, agitation speed, and viscosity of the medium. The gaseous concentrations were controlled by utilizing CampyPak Plus that reduced oxygen while augmenting carbon dioxide. Agitation of the broth facilitated the oxygen transfer to the cells, yet inhibited the growth at high rates. An increase of viscosity in the medium repressed the culture although this variable was relatively insignificant. The chemical constituents of the liquid broth were examined to establish an economic model for H. pylori cultivation. The microbe required a neutral pH for optimum growth, and yet was also able to proliferate in an acidic condition, presumably by releasing the acidity-modulating enzyme, urease. Cyclodextrin and casamino acid were investigated as growth enhancers in place of serum, while yeast extract unexpectedly inhibited the cells. A low concentration of glucose, the unique carbon source for the organism, increased the cell density, yet high concentrations resulted in an adverse effect. Under optimally dissolved gas conditions, the cell concentration in brucella broth supplemented with serum substitutes and glucose reached $1.6{\times}10^8$ viable cells/ml which was approximately 50% higher than that obtained in the liquid medium added with only cyclodextrin or serum.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.391-394
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• 2006

Growth characteristics of methane-propane clathrate hydrate, growing under different undercooling conditions, was investigated. After the water within pressurized vessel was fully saturated with guest gas molecules by agitation, medium was rapidly undercooled and maintained at the constant temperature. The growth of hydrate was always Initiated with film formations at the upper bounding surface of liquid pool. The visual observation using microscope revealed detailed features of subsequent crystal nucleation, migration, growth and interference occurring within liquid pool. A number of small crystals ascended and settled at the hydrate film. When undercooling was small $({\Delta}T=3.2K)$, some of the settled crystals slowly grew into faceted columns. As the undercooling increased, the downward growth of crystals underneath the hydrate film became dendritic and occurred with greater rate and with finer arm spacing. The shapes of the floating crystals were diverse and included octahedron and triangular or hexagonal platelet When the undercooling was small, the octahedral crystals were found dominant. As the undercooling increased, the shape of the floating crystals also became dendritic. The detailed characteristics of floating crystals were reported in this study.

• 대한화학회지
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• 제21권6호
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• pp.449-452
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• 1977

脂質 生産의 새로운 供給源으로 고려될 수 있는 石油炭化水素 醱酵에 의한 菌體脂質의 生成에 있어서 炭化水素의 炭素數의 影響과 그 脂肪酸의 組成을 檢討하였다. 菌株로서 Rhodotorula sp., 基質로서 炭素數가 짝수인 n-tetradecane과 n-hexadecane을 使用하여 容量 2l의 醱酵槽에서 溫度 $28^{\circ}C$, pH 4.0 ∼ 4.6, 酸素供給速度 0.4vvm, 攪拌速度 1000 rpm의 條件에서 醱酵시켜 生成된 菌體를 回收, 乾燥後 菌體脂質을 抽出하고 gas-liquid chromatography로 醱酵酸 組成을 檢索한 바, n-tetradecane과 n-hexadecane을 基質로 한 경우, 生成菌體의 脂質含量은 各各 12.0 및 25,8 %이었으며 菌體 脂肪酸은 大部分 炭素數가 짝수인 脂肪酸으로 構成되어 있었다.

• 한국환경과학회지
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• 제26권6호
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• pp.711-717
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• 2017

Dielectric Barrier Discharge (DBD) plasma is a new technique for use in environmental pollutant degradation, which is characterized by the production of hydroxyl radicals as the primary degradation species. Due to the short lifetime of the chemically active species generated during the plasma reaction, the dissolution of the plasma gas has a significant effect on the reaction performance. The plasma reaction performance can be enhanced by combining the basic plasma reactor with a homogenizer system in which the bubbles are destroyed and turned into micro-bubbles. For this purpose, the improvement of the dissolution of plasma gas was evaluated by measuring the RNO (N-dimethyl-4-nitrosoaniline, an indicator of the generation of OH radicals). Experiments were conducted to evaluate the effects of the diameter, rotation speed, and height of the homogenizer, pore size, and number of the diffuser and the applied voltage on the plasma reaction. The results showed that the RNO removal efficiency of the plasma reactor combined with a homogenizer is two times higher than that of the conventional one. The optimum rotor size and rotation speed of the homogenizer were 15.1 mm, and 19,700 rpm, respectively. Except for the lowest pore size distribution of $10-16{\mu}m$, the pore size of the diffuser showed little effect on RNO removal.

• Biotechnology and Bioprocess Engineering:BBE
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• 제10권3호
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• pp.270-274
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• 2005

A reactor-scale hydrogen (H2) production via the water-gas shift reaction of carbon monoxide (CO) and water was studied using the purple nonsulfur bacterium, Rhodopseudomonas palustris P4. The experiment was conducted in a two-step process: an aerobic/chemoheterotrophic cell growth step and a subsequent anaerobic $H_2$ production step. Important parameters investigated included the agitation speed. inlet CO concentration and gas retention time. P4 showed a stable $H_2$ production capability with a maximum activity of 41 mmol $H_2$ g $cell^{-1}h^{-1}$ during the continuous reactor operation of 400 h. The maximal volumetric H2 production rate was estimated to be 41 mmol $H_2 L^{-1}h^{-1}$, which was about nine-fold and fifteen-fold higher than the rates reported for the photosynthetic bacteria Rhodospirillum rubrum and Rubrivivax gelatinosus, respectively. This is mainly attributed to the ability of P4 to grow to a high cell density with a high specific $H_2$ production activity. This study indicates that P4 has an outstanding potential for a continuous H2 production via the water-gas shift reaction once a proper bioreactor system that provides a high rate of gas-liquid mass transfer is developed.

• Korean Chemical Engineering Research
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• 제53권2호
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• pp.174-180
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• 2015

8자 진동교반조에 대해 실험적으로 유동상태를 관찰하여 혼합 가시화, 소요동력, 고-액 및 기-액 물질이동에 대한 여러가지의 특성을 측정하였다. 진동수가 증가하면 유동상태, 혼합시간 소요동력 및 물질이동계수는 규칙적으로 변하지 않으므로 조작조건의 선정이 중요하다. 어떤 진동수에서라도 Fr = 0.095 이상에서는 실험적으로 명확하게 되었다. 이때 교반조내 유체는 선회류형으로 되어 혼합에 적합한 상태가 되고, 8자 진동교반에서의 최적 조작범위는 왕복 진동교반 보다도 넓었다. 8자 진동교반과 기존의 선회진동교반내의 고-액간 물질이동계수는 완전히 같은 식으로 상관되었다. 또한 기-액간 물질이동용량계수도 기존의 선회진동교반에서의 식과 같은 형태의 상관식으로 나타났다.