• Title/Summary/Keyword: two-step cooling

Search Result 66, Processing Time 0.022 seconds

Cryopreservation of Scutellaria baicalensis Cells by Two-step Cooling Method

  • Seo, Weon-Taek;Kim, Suk-Weon;Liu, Jang-Ryol;Kim, Ik-Hwan;Park, Young-Hoon;Choe, Tae-Boo
    • Journal of Microbiology and Biotechnology
    • /
    • v.6 no.3
    • /
    • pp.209-212
    • /
    • 1996
  • A two-step cooling technique has been developed for cryopreservation of suspension cultured Scutellaria baicalensis cells. Efficient regrowth of cryopreserved cells was obtained in cryoprotected cells with a mixture of 1.5 M glycerol and 0.4 M sucrose in Schenk and Hildebrandt medium without pretreatment in high osmotic medium. Optimum freezing conditions were found to be a cooling rate of $0.5^{\circ}C$ min from $4^{\circ}C$ to $-40^{\circ}C$, and then retaining samples at $-40^{\circ}C$ for 30 min prior to plunging into liquid nitrogen. A regrowth rate of approximately 95$%$ was obtained after three month storage in liquid nitrogen. Callus cultures established from the cryopreserved cells were found to produce the same patterns of flavonoid accumulation and retain their baicalin producing activity.

  • PDF

Optimal Design for Indoor Thermal Environment based on CFD Simulation and Genetic Algorithms (CFD 연성해석과 유전자 알고리즘을 이용한 실내 열환경 최적설계에 관한 연구)

  • 김태연;이윤규
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.16 no.2
    • /
    • pp.111-120
    • /
    • 2004
  • The optimal design method of indoor thermal environment using CFD coupled simulation and genetic algorithms (GA) is developed in this study. CFD could analyze the thermal environment considering the distribution of temperature, velocity, etc. in a room. Therefore, It would be appropriate to use CFD for the optimal design method considering their distribution. In this paper, the optimal design means the most appropriate boundary conditions of the room among the conditions where the design target of indoor therm environment is achieved. Two step optimal indoor thermal environment design method is proposed. It includes the GA for searching the optimal indoor thermal environment design. To examine the performance of this method, the optimal design of hybrid ventilation system, which uses the natural cross ventilation and the radiation-cooling panel is conducted. The optimal design which satisfies the design target (thermal comfort, minimum cooling load, minimum vertical temperature difference) is found using two step optimal design method.

Cryopreservation of Sporothalli of the Genus Porphyra (Bangiales, Rhodophyta) from Korea

  • Jo, Young-Hyun;Kang, Sung-Pil;Seo, Tae-Ho;Choi, Sung-Je;Kho, Kang-Hee;Kuwano, Kazuyoshi;Saga, Naotsune;Kim, Min-Yong;Shin, Jong-Ahm
    • ALGAE
    • /
    • v.18 no.4
    • /
    • pp.321-331
    • /
    • 2003
  • Cryopreservation of sporothalli of the red alga Porphyra (P. seriata, P. yezoensis, P. tenera, P. pseudolinearis and P. dentata) was performed by the two-step cooling method in liquid nitrogen. The algal samples were suspended in various cryoprotective solutions, and slowly cooled to -40$^{\circ}C$ in 4 hours using a programmed freezer. After the first slow cooling the suspensions with cryoprotectants were immediately immersed in liquid nitrogen. The suspension from the programmed freezer was thawed quickly by agitation of the vial in a water bath at 40°C. When ice in the suspension of cryogenic vial was mostly melted, the vial was transferred to an ice bath for complete melting of the residual ice. The cryoprotectants in the vial were washed off by gradual dilution with seawater. The viability of the cell was assessed with neutral red staining. The viability of Porphyra samples ranged 54.6-70.9% when the mixed suspension of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater used as a cryoprotectant.

Development of Thermal Performance Prediction for Large Planar Military Antenna with Multi-Cooling Channels (다중 냉각유로가 적용된 수랭식 군사용 대면적 안테나의 열성능 예측 기술)

  • YeRyun Lee;SungWook Jang;PilGyeong Choi;NohJin Kwak;JunJung Park
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.27 no.1
    • /
    • pp.43-50
    • /
    • 2024
  • Large planar military antenna boasts a range of electrical components, including TRA(Transmit-Receive Assembly), signal processors, etc. which engage in computations and calculations. These processes generate a significant amount of heat, leading to unforeseen consequences for the equipment. To mitigate these adverse effects, it's imperative to implement a cooling system that can effectively reduce heat-related issues. Given the antenna's intricate nature and the multitude of components it houses, a two-step estimation process is necessary. The first step involves a comprehensive model calculation to determine the total flow characteristics, while the second step entails a thermal analysis of individual TRA set. In this study, we depicted an antenna set using simplified 3D models of its components, considering their material and thermal properties. The sequential analysis process facilitated the calculation of branched flow rates, providing insights into the individual TRA. This approach also allowed us to design a cooling system for the TRA set, assessing its thermal stability in high-temperature environments. To ensure the optimal performance of TRA, breaking down the analysis into stages based on the cooling system's structure can assist operators in predicting numerical results more effectively.

Change of Secondary Dendrite Arm Spacing of Hypoeutectic Al-Si Alloys according to Si Content and Cooling Rate (아공정 Al-Si 합금에서 Si 함량과 냉각속도에 따른 제이차수지상간격의 변화)

  • Park, Kyeong-Seob;Kim, Hee-Soo
    • Journal of Korea Foundry Society
    • /
    • v.37 no.4
    • /
    • pp.108-114
    • /
    • 2017
  • In this study, we investigated the effect of the Si content on the secondary dendrite arm spacing (SDAS) of hypoeutectic Al-Si binary alloys in the range of 4~10 wt% Si. Cooling curves were measured during the solidification of the alloy cast in a step-wise mold. We compared two kinds of solidification time: the first is the total solidification time for both dendritic and eutectic growth, and the second is the solidification time for only dendritic growth. The proportional constant in the relationship between SDAS and cooling rate was estimated, as this constant represents the stability of the cast microstructure. The proportional constant decreased with the Si contents from 4 wt% to 8 wt%, and it remains relatively uniform with up to 10 wt% of Si.

Crystallization of High Purity Ammonium Meta-Tungstate for production of Ultrapure Tungsten Metal

  • Choi, Cheong-Song
    • Proceedings of the Korea Association of Crystal Growth Conference
    • /
    • 1997.10a
    • /
    • pp.1-5
    • /
    • 1997
  • The growth mechanism of AMT(Ammonium Meta-Tungstate) crystal was interpreted as two-step model. The contribution of the diffusion step increased with the increase of temperature, crystal size, and supersaturation. The crystal size distribution from a batch cooling crystallizer was predicted by the numerical solution of a mathematical model which uses the kinetics of nucleation and crystal growth. Temperature control of a batch crystallizer was studied using Learning control algorithm. The purity of AMT crystal producted in this investigation was above 99.99%.

  • PDF

Enhancement of the Soft Magnetic Properties of Co-based Amorphous Alloy by Two-step Cooling Method. (이단 냉각열처리에 의한 Co계 비정질 합금의 연자기 특성 향상)

  • 양재호;김만중;정연춘;김윤배;김택기
    • Journal of the Korean Magnetics Society
    • /
    • v.10 no.1
    • /
    • pp.7-10
    • /
    • 2000
  • The soft magnetic properties of Co-based amorphous alloy have been studied as a function of cooling condition after annealing. The F&W treatment (furnace cooling to 25$0^{\circ}C$ then water quenching) could increase 60~10$0^{\circ}C$ more the initial permeability than those of furnace cooled or water quenched alloys. These results are investigated in terms of thermal stress and ordering of magnetic ion pairs.

  • PDF

Comparison of Recombination Methods ad Cooling Factors in Genetic Algorithms Applied to Folding of Protein Model System

  • U, Su Hyeong;Kim, Du Il;Jeong, Seon Hui
    • Bulletin of the Korean Chemical Society
    • /
    • v.21 no.3
    • /
    • pp.281-290
    • /
    • 2000
  • We varied recombination method of fenetic algorithm (GA), i.e., crossover step, to compare efficiency of these methods, and to find more optimum GA method. In one method (A), we select two conformations(parents) to be recombined by systematic combination of lowest energy conformations, and in the other (B), we select them in a ratio proportional to the energy of the conformation. Second variation lies in how to select crossover point. First, we select it randomly(1). Second, we select range of residues where internal energy of the molecule does not vary for more than two residues, select randomly among such regions, and we select either thr first (2a) or the second residue (2b) from the N-terminal side, or the first (2c) or the second residue (2d) from the C-terminal side in the selected region for crossover point. Third, we select longest such hregion, and select such residue(as cases 2) (3a, 3b, 3c or 3d) of the region. These methods were tested in a 2-dimensionl lattice system for 8 different sequences (the same ones used by Unger and Moult., 1993). Results show that compared to Unger and Moult's result(UM) which corresponds to B-1 case, our B-1 case performed similarly in overall. There are many cases where our new methods performed better than UM for some different sequences. When cooling factor affecting higher energy conformation to be accepted in Monte Carlo step was reduced, our B-1 and other cases performed better than UM; we found lower energy conformers, and found same energy conformers in a smaller steps. We discuss importance of cooling factor variation in Monte Carlo simulations of protein folding for different proteins. (A) method tends to find the minimum conformer faster than (B) method, and (3) method is superior or at least equal to (1) method.

Finite Element Analysis for Shape Prediction on Micro Lens Forming (마이크로 렌즈 성형시 형상예측을 위한 유한요소해석)

  • 전병희;홍석관;표창률
    • Transactions of Materials Processing
    • /
    • v.11 no.7
    • /
    • pp.581-588
    • /
    • 2002
  • Among the processes to produce micro lens, the process using press molding is a new technology to simplify the process, but it contains many unknown variables. The press-molding process proposed in this paper was simplified into two step process, the first step is the pressing to design the preform for glass element, the second step is the annealing to reduce the residual stress. It is important to estimate the amount of shrinkage of glass gob and the residual stress during process. It Is difficult to evaluate the process variables as mentioned above through the experiment. The influences due to process variables was evaluated by using FEM parametric analysis. The results in this paper can be applicable to produce micro lens.

Effects of Operating Conditions on Adsorption and Desorption of Benzene in TSA Process Using Activated Carbon and Zeolite 13X (활성탄과 제올라이트 13X 충진탑을 사용한 TSA 공정에서 조업조건이 벤젠의 흡착 및 탈착에 미치는 영향)

  • Jung, Min-Young;Suh, Sung-Sup
    • Applied Chemistry for Engineering
    • /
    • v.29 no.5
    • /
    • pp.594-603
    • /
    • 2018
  • The effects of operating conditions such as benzene concentration, nitrogen flow rate, steam flow rate, and bed temperature on TSA process were experimentally investigated as a potential VOC removal technology using two kinds of beds packed with activated carbon and zeolite 13X. The TSA cycle studied was composed of the adsorption step, steam desorption step, and drying and cooling step. At 2% benzene concentration, the total adsorption amounts of zeolite 13X and activated carbon were 4.44 g and 3.65 g, respectively. Since the zeolite 13X has a larger packing density than that of the activated carbon, the larger benzene amount could be adsorbed in a single cycle. Increasing the water vapor flow rate to 75 g/hr at 2% benzene concentration reduced the desorption time from 1 hr to a maximum of 33 min. If the desorption time is shortened, the drying and cooling step period can be relatively increased. Accordingly, the steam removal and bed cooling could be sufficiently performed. The desorption amounts increased with the increase of the bed temperature. However, the energy consumption increased while the desorption amount was almost constant above $150^{\circ}C$. In the continuous cycle process, when the amount of remained benzene at the completion of the regeneration step increased, it might cause a decrease in the working capacity of the adsorbent. The continuous cycle process experiment for zeolite 13X showed that the amount of remained benzene at the end of regeneration step maintained a constant value after the fourth cycle.