• 대한화학회지
• /
• 제13권2호
• /
• pp.187-193
• /
• 1969

As part of an extensive program on the microbiological oxidation of hydrocarbons, reaction conditions and nutrients consumption of candida lipolytica grown on alkane as carbon source were studied. For optimum growth of yeast, the conditions of pH 5, temperature $30^{\circ}C$, carbon number $C_{16}$& $C_{18}$aeration 25.6 1/l/hr, agitation 3000 r.p.m., hydrocarbon concentration 10% were obtained. Carbon and nitrogen balance related to these conditions were also investigated. In the course of this investigation, some significant effects of pH and carbon number of hydrocarbon variation were observed.

• 폴리머
• /
• 제28권2호
• /
• pp.170-176
• /
• 2004

반응조건에 따른 실록산으로 코팅된 마그네타이트 나노입자의 크기 및 분포를 동적광산란을 이용하여 조사하였다. FT-IR로부터 마그네타이트의 표면에 히드록시기가 존재함을 확인하였고 이 히드록시기는 코팅된 실록산의 실란올과 수소결합을 이루고 있음이 확인되었다. 제조된 나노입자의 크기는 반응온도가 증가함에 따라 입자크기는 증가하였고 단량체 함량과 교반 속도의 증가에 따라서는 감소하였다. 입자 크기 분포는 반응조건에 따라서 약간의 변화는 있지만 전체적으로 14∼41nm 크기의 범위를 나타냈다. 제조된 마그네타이트의 자성특성은 vibrating sample magnetometer를 이용하여 초상자성임이 확인되었고 실록산으로 코팅된 나노입자 역시 초상자성을 나타냄을 확인하였다. 반응조건에 따라서는 반응온도가 증가할수록 포화자화강도는 증가하였고 단량체 함량과 교반 속도가 증가함에 따라서 포화자화강도가 감소하는 것을 나타내었다.

• 한국산업융합학회 논문집
• /
• 제23권4_2호
• /
• pp.617-626
• /
• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
• /
• pp.287-290
• /
• 2000

회분배양에서 교반속도와 통기량에 대한 영향을 살펴본 결과 400 rpm과 1.0 vvm의 조건에서 균체량은 25.1 g/L, 다당체는 2.5 g/L로 가장 높게 생성되었다. 회분배양을 기초로 균체량과 다당체 생성을 높이기 위해 glucose를 대수기에 공급한 결과 배양 6일째 균체량은 29,2 g/L, 다당체 생성은 3.3 g/L로 회분배양보다 우수한 결과를 보였다.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
• /
• pp.342-348
• /
• 2001

This study was conducted to obtain granular crystalline gypsum that can be used as raw material for plaster boards or cements from waste Plaster board. We could disintegrate preferentially gypsum to gypsum needle in 10${\mu}{\textrm}{m}$ or less size among the contents of waste plaster board (gypsum, paper, fiber, and inorganic material .etc.) by hydration afterwards the dehydration of crushed waste plaster board. In this case, the optimum conditions for minimizing the size of gypsum were dehydration rate of 75%~ 85%, hydration concentration of 10~20%, agitation speed of 250~400rpm, crushing size of 2cm or less. Gypsum of 98.21% grade was recovered with 99.0% yield from under screenings of 325mesh wet screening which followed by the dehydration-hydration process performed in the conditions of dehydration rate of 80%, hydration concentration of 15%, agitation speed of 300rpm, crushing size of 2cm or less. Subsequently, Plate-like Crystalline gypsum of is 151${\mu}{\textrm}{m}$ size and the grade of 99.49% with the Yield of 98.0% from the upper screenings of 270mesh wet screening carried out after the re-crystallization of the recovered gypsum needle slurry.

• 한국주조공학회지
• /
• 제13권6호
• /
• pp.524-531
• /
• 1993

Dispersion behaviors of SiC particles and microstructures in Al-2%Si/SiCp composite prepared by Rheo-compocasting were studied with change of fabrication conditions(slurry temperature, agitation time) and additions of Mg($0{\sim}3wt.%$). Also, the microhardness change of matrix, interface and total in composites were examined with additions of Mg($0{\sim}3wt.%$). The dispersion of particles in the composites became relatively homogeneous with increase of Mg additions, agitation time and decrease of slurry temperature. Rate of occupied area by particle in matrix was increased as increase of Mg additions due to improvement of wettability between SiC particle and matrix. A favorable composites were obtained by melting under Ar atmospheric SiCp injection and bottom pouring system. According to the analysis of X-ray diffraction, $Mg_2Si$, $Al_4C_3$, $SiO_2$ and MgO, etc, intermetallic compounds were formed by chemical interreaction at interface of matrix and particles. The microhardness of interface is higher than that of matrix due to more strengthening of above intermetallic compounds. It was considered that the total hardness of the composites is improved by dispersing of SiCp and addition of Mg.

• 자원리싸이클링
• /
• 제10권6호
• /
• pp.43-52
• /
• 2001

This study was conducted to obtain granular crystalline gypsum that can be used as raw material for Plaster boards or cements from waste Plaster board. Gypsum could be Preferentially disintegrated to gypsum needle in $10\mu\textrm{m}$ or less size by hydration after the dehydration of crushed waste Plaster board. The finer the gypsum needle, it is easier to remove coarse impurities and to recover the gypsum needle. The optimum conditions for obtain the finer gypsum size were dehydration rate of 75~85%, solid concentration at hydration of 10~15%, agitation speed of 250~400 rpm, crushing size before dehydration of 2 cm or less. Gypsum of 98.21% grade was recovered with 99.0% yield as the undersize of 325 mesh wet screening followed by the dehydration-hydration process performed at the conditions of dehydration rate of 80%, solid concentration at hydration of 15%, agitation speed of 300 rpm, crushing size before dehydration of 2 cm or less. After the recrystallization of recovered gypsum, Plate-like gypsum of $151\mu\textrm{m}$ size with 99.49% grade was obtained as the oversize of 270 mesh in a wet screening.

• 한국식생활문화학회지
• /
• 제34권3호
• /
• pp.361-368
• /
• 2019

The purpose of this study was to establish the best optimized extraction condition for the optimal development of fresh maca beverage using low temperature extraction and enzyme treatment. Low temperatures were applied to prevent heat-related nutritional loss during the extraction process. Best extraction conditions were investigated based on the ratio of maca to water, the ratio of enzymes, extraction temperature and time, and agitation. The optimal enzyme conditions were also examined after the treatment of cellulase:pectinase mixture to maintain the original color and flavor, as well as to increase the extraction yield. When cellulase:pectinase was 1:1, the extraction rate ranged from 77.84 to 79.29%. In addition, the best extraction rate was found when maca was mixed with twice volume of water and incubated at $45^{\circ}C$ ($84.05{\pm}0.32%$) with 90 rpm ($87.13{\pm}0.46%$) agitation for 3 hours ($84.73{\pm}0.29%$). Furthermore, sensory evaluation showed a high score in flavor, sweetness, and overall acceptability after adding 3% jujube concentrate into a fresh maca beverage.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제1권1호
• /
• pp.32-35
• /
• 1996

Amoving aeration-membrane (MAM) bioreactor was employed for the production of 2$\mu$g/mL of tissue type Plasminogen Activator (tPA)in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating condition, shear stress was as low as 0.65 dynes/$\textrm{cm}^2$ at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2$\mu$g tPA/mL while maintaining a high cell denisty of 1.0$\times$107 viable cell/mL.

• 한국의류산업학회지
• /
• 제3권5호
• /
• pp.455-465
• /
• 2001

Assessing soil removal is of interest to the washing machine industry because of government-mandated energy savings and changes in detergent formulation and consumer laundry practices. We designed this study to examine the laundry process from a holistic perspective by integrating factors perceived to be of importance. Our purpose was to assess the impact of selected variables (fabric and soil type, wash temperature and time. detergent amount, and degree of agitation) on soil removal using accelerated laundry conditions. We used the Taguchi method to develop the research design and ANOVA to analyze the data. Although soil removal was affected by fabric type, soil type, type and amount of detergent, degree of agitation, wash time and temperature, and water hardness and volume, wash temperature was the most significant variable.