• Title/Summary/Keyword: Droplet Model

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A Sensitivity Study of the Number of Parcels to the Numerical Simulation of Sprinkler Sprays (통계적 액적군집수에 따른 스프링클러 분무해석의 민감도에 관한 연구)

  • Kim, Sung-Chan;Lee, Sang-Woo;Park, Won-Ju
    • Fire Science and Engineering
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    • v.23 no.1
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    • pp.48-54
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    • 2009
  • The present study has been performed to investigate the effect of statistical number of droplets on the simulation of the sprinkler spray using fire field model. In order to simulate the sprinkler spray characteristics, the present study uses NIST Fire Dynamics Simulator version 5.2. A group of Lagrangian particles with similar droplet characteristics, such as diameter, velocity, temperature and so on, is represented by parcel concept to decrease the total number of droplets tracked in the simulation. The present study introduces a new parameter to represent the ratio between real number of droplets and computational parcels. The dependency of the number of parcels on the fire suppression characteristics and spray patterns is quantitatively examined for different ratio between the real number of droplets and computational parcels.

Microemulsion-based hydrogels for enhancing epidermal/dermal deposition of topically administered 20(S)-protopanaxadiol: in vitro and in vivo evaluation studies

  • Kim, Ki-Taek;Kim, Min-Hwan;Park, Ju-Hwan;Lee, Jae-Young;Cho, Hyun-Jong;Yoon, In-Soo;Kim, Dae-Duk
    • Journal of Ginseng Research
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    • v.42 no.4
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    • pp.512-523
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    • 2018
  • Background: 20(S)-Protopanaxadiol (20S-PPD) is a fully deglycosylated ginsenoside metabolite and has potent dermal antiaging activity. However, because of its low aqueous solubility and large molecular size, a suitable formulation strategy is required to improve its solubility and skin permeability, thereby enhancing its skin deposition. Thus, we optimized microemulsion (ME)-based hydrogel (MEH) formulations for the topical delivery of 20S-PPD. Methods: MEs and MEHs were formulated and evaluated for their particle size distribution, morphology, drug loading capacity, and stability. Then, the deposition profiles of the selected 20S-PPD-loaded MEH formulation were studied using a hairless mouse skin model and Strat-M membrane as an artificial skin model. Results: A Carbopol-based MEH system of 20S-PPD was successfully prepared with a mean droplet size of 110 nm and narrow size distribution. The formulation was stable for 56 d, and its viscosity was high enough for its topical application. It significantly enhanced the in vitro and in vivo skin deposition of 20S-PPD with no influence on its systemic absorption in hairless mice. Notably, it was found that the Strat-M membrane provided skin deposition data well correlated to those obtained from the in vitro and in vivo mouse skin studies on 20S-PPD (correlation coefficient $r^2=0.929-0.947$). Conclusion: The MEH formulation developed in this study could serve as an effective topical delivery system for poorly soluble ginsenosides and their deglycosylated metabolites, including 20S-PPD.

Experimental determination of liquid entry pressure (LEP) in vacuum membrane distillation for oily wastewaters

  • Racz, Gabor;Kerker, Steffen;Schmitz, Oliver;Schnabel, Benjamin;Kovacs, Zoltan;Vatai, Gyula;Ebrahimi, Mehrdad;Czermak, Peter
    • Membrane and Water Treatment
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    • v.6 no.3
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    • pp.237-249
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    • 2015
  • In this study we investigate a laboratory scale vacuum membrane distillation system to produce pure water from model oil in water emulsion. Experimental determination of liquid entry pressure (LEP) of a commercial Durapore$^{TM}$ GVPH flat sheet membrane using model emulsions in various oil concentrations has been carried out. Two different methods of liquid entry pressure determination - a frequently used, so-called static and a novel dynamic method - have been investigated. In case of static method, LEP value was found to be 2.3 bar. No significant effect of oil content on LEP was detected up to 3200 ppm. In contrast, LEP values determined with dynamic method showed strong dependence on the oil concentration of the feed and decreased from 2.0 bar to a spontaneous wetting at 0.2 bar in the range 0-250 ppm, respectively. Vacuum membrane distillation tests were also performed. The separation performance is evaluated in terms of flux behavior, total organic carbon removal and droplet size distribution of the feed and final retentate. No significant effect of oil content on the flux was found ($5.05{\pm}0.31kgm^{-2}h^{-1}$) up to 250 ppm, where a spontaneous wetting occurred. High separation performance was achieved along with the increasing oil concentration between 93.4-97.0%.

An intercomparison study between optimization algorithms for parameter estimation of microphysics in Unified model : Micro-genetic algorithm and Harmony search algorithm (통합모델의 강수물리과정 모수 최적화를 위한 알고리즘 비교 연구 : 마이크로 유전알고리즘과 하모니 탐색 알고리즘)

  • Jang, Jiyeon;Lee, Yong Hee;Joo, Sangwon
    • Journal of the Korean Institute of Intelligent Systems
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    • v.27 no.1
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    • pp.79-87
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    • 2017
  • The microphysical processes of the numerical weather prediction (NWP) model cover the following : fall speed, accretion, autoconversion, droplet size distribution, etc. However, the microphysical processes and parameters have a significant degree of uncertainty. Parameter estimation was generally used to reduce errors in NWP models associated with uncertainty. In this study, the micro- genetic algorithm and harmony search algorithm were used as an optimization algorithm for estimating parameters. And we estimate parameters of microphysics for the Unified model in the case of precipitation in Korea. The differences which occurred during the optimization process were due to different characteristics of the two algorithms. The micro-genetic algorithm converged to about 1.033 after 440 times. The harmony search algorithm converged to about 1.031 after 60 times. It shows that the harmony search algorithm estimated optimal parameters more quickly than the micro-genetic algorithm. Therefore, if you need to search for the optimal parameter within a faster time in the NWP model optimization problem with large calculation cost, the harmony search algorithm is more suitable.

Analysis of Fire Suppression Efficiency for Intermittent Water Spray Pattern by Fire Dynamics Simulator (FDS를 이용한 교번식 미분무방식의 소화 성능 분석)

  • Jee, Moon-Hak;Lee, Byung-Kon
    • Fire Science and Engineering
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    • v.22 no.3
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    • pp.216-220
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    • 2008
  • Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively lower than that of larger water droplet and the infiltration of water mist to the fire source is not effective. Contribution of evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist pattern is expected to improve the penetration force of water mist as well as the air expelling capability with the stratified spray characteristics. At this paper, we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis can support the basic concept to the development of the prototype of water mist nozzle.

Studies on the use of computer aided semen analysis(CASA) technology for fertility prediction in Korean native cattle (한우에서 Computer aided semen analysis(CASA) 기법을 이용한 수태율 예측에 관한 연구)

  • Lee, Kang-nam;Lee, Byeong-chun;Hwang, Woo-suk
    • Korean Journal of Veterinary Research
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    • v.38 no.4
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    • pp.882-897
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    • 1998
  • This experiment was conducted to predict the effects of motional characteristics on the fertility of Korean native cattle(KNC) by using CASA technology and in vitro fertilization system. Twenty-six KNC frozen semen straws were obtained from Korean KNC improvement department, livestock improvement main division, national livestock cooperatives federation in Korea. Specimens were allowed to thaw at $37^{\circ}C$ for 30 sec in water bath. Semen analysis was performed on semen image analysis system(SIAS, Medical supply, Korea) adjusted to the gate settings and used the semen droplet ($5{\mu}l$) placed on Makler counting chamber(Sefi medical instrument, Israel) prewarmed at $37^{\circ}C$. The same person used the same micropipette to fill the Makler counting chamber. A total of 150 or more of sperms were analysed in each specimen by a single trained person by scanning at least 5 to 10 fields. The oocytes collection, in vitro maturation, IVF, in vitro culture and determination of the cleavage rate were performed by the technique, as described by Hwang et al (1997). Statistical analysis was done by linear regression with use of the Sigma plot program on a IBM personal computer. The cleavage rate in vitro fertilized oocyte was significantly correlated(P<0.05) with MOT, VCL, VSL, VAP, ALH, BCF and MAD, but not CON, LIN, STR, WOB, DNM, DNC and HYP in regressional analysis. The results show that some kinematic characteristics of frozen-thawed semen by CASA can be predict the fertility in in vitro model system.

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Study of Nano-emulsion Formation by Different Dilution Method (희석 방법에 따른 나노에멀젼 형성 연구)

  • Cho, Wan-Goo;Han, Sang-Gil
    • Journal of the Society of Cosmetic Scientists of Korea
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    • v.38 no.3
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    • pp.201-207
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    • 2012
  • The influence of different dilution procedures on the properties of oil-in-water (O/W) nano-emulsions obtained by dilution of oil-in-ethanol (O/E) microemulsions with water has been studied. The system water/ethanol/nonionic surfactant/silicone oil with ethanol was chosen as model system. The dilution procedures consisted of adding water (or microemulsion) stepwise. By mixing O/E microemulsions into water, nano-emulsions with droplet diameters of 30 nm were obtained. In contrast, by mixing water into O/E microemulsion, emulsions with diameter of 400 nm were obtained The dilution methods were shown to be a key factor determining the properties of the emulsions. There were no change in diameters of nanoemulsion droplets against time, however sizes of droplets in the emulsion with larger droplets were increased with time and the mechanism of unstability was thought to be Ostwald ripening.

Allithiamine Exerts Therapeutic Effects on Sepsis by Modulating Metabolic Flux during Dendritic Cell Activation

  • Choi, Eun Jung;Jeon, Chang Hyun;Park, Dong Ho;Kwon, Tae-Hwan
    • Molecules and Cells
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    • v.43 no.11
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    • pp.964-973
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    • 2020
  • Recent studies have highlighted that early enhancement of the glycolytic pathway is a mode of maintaining the proinflammatory status of immune cells. Thiamine, a wellknown co-activator of pyruvate dehydrogenase complex, a gatekeeping enzyme, shifts energy utilization of glucose from glycolysis to oxidative phosphorylation. Thus, we hypothesized that thiamine may modulate inflammation by alleviating metabolic shifts during immune cell activation. First, using allithiamine, which showed the most potent anti-inflammatory capacity among thiamine derivatives, we confirmed the inhibitory effects of allithiamine on the lipopolysaccharide (LPS)-induced pro-inflammatory cytokine production and maturation process in dendritic cells. We applied the LPS-induced sepsis model to examine whether allithiamine has a protective role in hyper-inflammatory status. We observed that allithiamine attenuated tissue damage and organ dysfunction during endotoxemia, even when the treatment was given after the early cytokine release. We assessed the changes in glucose metabolites during LPS-induced dendritic cell activation and found that allithiamine significantly inhibited glucose-driven citrate accumulation. We then examined the clinical implication of regulating metabolites during sepsis by performing a tail bleeding assay upon allithiamine treatment, which expands its capacity to hamper the coagulation process. Finally, we confirmed that the role of allithiamine in metabolic regulation is critical in exerting anti-inflammatory action by demonstrating its inhibitory effect upon mitochondrial citrate transporter activity. In conclusion, thiamine could be used as an alternative approach for controlling the immune response in patients with sepsis.

Investigation of the Optical and Cloud Forming Properties of Pollution, Biomass Burning, and Mineral Dust Aerosol

  • Lee Yong-Seop
    • Proceedings of the Korea Air Pollution Research Association Conference
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    • 2006.04a
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    • pp.55-56
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    • 2006
  • This thesis describes the use of measured aerosol size distributions and size-resolved hygroscopic growth to examine the physical and chemical properties of several particle classes. The primary objective of this work was to investigate the optical and cloud forming properties of a range of ambient aerosol types measured in a number of different locations. The tool used for most of these analyses is a differential mobility analyzer / tandem differential mobility analyzer (DMA / TDMA) system developed in our research group. To collect the data described in two of the chapters of this thesis, an aircraft-based version of the DMA / TDMA was deployed to Japan and California. The data described in two other chapters were conveniently collected during a period when the aerosol of interest came to us. The unique aspect of this analysis is the use of these data to isolate the size distributions of distinct aerosol types in order to quantify their optical and cloud forming properties. I used collected data during the Asian Aerosol Characterization Experiment (ACE-Asia) to examine the composition and homogeneity of a complex aerosol generated in the deserts and urban regions of China and other Asian countries. An aircraft-based tandem differential mobility analyzer was used for the first time during this campaign to examine the size-resolved hygroscopic properties of particles having diameters between 40 and 586 nm. Asian Dust Above Monterey (ADAM-2003) study was designed both to evaluate the degree to which models can predict the long-range transport of Asian dust, and to examine the physical and optical properties of that aged dust upon reaching the California coast. Aerosol size distributions and hygroscopic growth are measured in College Station, TX to investigate the cloud nucleating and optical properties of a biomass burning aerosol generated from fires on the Yucatan Peninsula. Measured aerosol size distributions and size-resolved hygroscopicity and volatility were used to infer critical supersaturation distributions of the distinct particle types that were observed during this period. The predicted CCN concentrations were used in a cloud model to determine the impact of the different aerosol types on the expected cloud droplet concentration. RH-dependent aerosol extinction coefficients are calculated at a wavelength of 550 nm.

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Study on the Passive Shock/Boundary Layer Interaction Control in Transonic Moist Air Flow (습공기 유동에서 발생하는 충격파와 경계층 간섭의 피동제어에 관한 연구)

  • Baek, Seung-Cheol;Kwon, Soon-Bum;Kim, Heuy-Dong
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.30 no.8
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    • pp.21-29
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    • 2002
  • In the present study, a passive control method, using a porous wall and cavity system, is applied to the shock wave/boundary layer interactions in transonic moist air flow. The two-dimensional, unsteady, compressible, Navier-Stokes equations, which are fully coupled with a droplet growth equation, are solved by the third-order MUSCL type TVD finite difference scheme. Baldwin-Lomax model is employed to close the governing equations. In order to investigate the effectiveness of the present control method, the total pressure loss of the flow and the time-dependent behaviour of shock motions are analyzed in detail. The computed results show that the present passive control method considerably reduces the total pressure losses due to the shock wave/boundary layer interaction in transonic moist air flow and suppresses the unsteady shock wave motions over the airfoil as well. It is also found that the location of the porous ventilation significantly affects the control effectiveness.