• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.237-241
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• 2001

Our goal is to present a simple volume-of-fluid type interface-tracking algorithm to compressible two-phase flow in two space dimensions. The algorithm uses a uniform underlying Cartesian grid with some cells cut by the tracked interfaces into two subcells. A volume-moving procedure that consists of two basic steps: (1) the update of volume fractions in each grid cell at the end of the time step, and (2) the reconstruction of interfaces from discrete set of volume fractions, is employed to follow the dynamical behavior of the interface motion. As in the previous work with a surface-tracking procedure for general front tracking (LeVeque & Shyue 1995, 1996), a high resolution finite volume method is then applied on the resulting slightly nonuniform grid to update all the cell values, while the stability of the method is maintained by using a large time step wave propagation approach even in the presence of small cells and the use of a time step with respect to the uniform grid cells. A sample preliminary numerical result for an underwater explosion problem is shown to demonstrate the feasibility of the algorithm for practical problems.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.123-128
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• 2014

In this study, we have investigated the flow rate effects of Ag nanoparticle (NP) suspensions on the progress of the cell cycle by using a microfluidic image cytometry (${\mu}FIC$)-based approach. Compared with the conventional "static" exposure conditions, enhancements in G2 phase arrest were observed for the cells under continuously flowing "dynamic" exposure conditions. The "dynamic" exposure conditions, which mimic in vivo systems, induced an enhanced cytotoxicity by accelerating G2 phase arrest and subsequent apoptosis processes. Moreover, we have also shown that the increases in delivered NP dose due to the continuous supply of Ag NPs contributed dominantly to the enhanced cytotoxicity observed under the "dynamic" exposure conditions, while the shear stress caused by these slowly flowing fluids (i.e., flow rates of 6 and $30{\mu}L/h$) had only a minor influence on the observed enhancement in cytotoxicity.

• Journal of the Korean Graphic Arts Communication Society
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• v.28 no.2
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• pp.45-56
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• 2010

The computer simulation is presented of gravure ink transferring behavior and penetration to the paper when an gravure roller is used to transfer a printing ink onto a substrate. The three dimensional unsteady ink motion is simulated by Polyflow package software and experimented by IGT gravure printing test machine. The simulation is performed where the flow domain is bounded above by a stress free surface and bounded below by a moving substrate. Specific predictions are made for particular pattern of cells and substrates. Cell size and ink rheological properties are found to be the principal determination of transferring behavior. Simulation is currently restricted to the flow domain beneath the receding meniscus. Both Newtonian and shear thinning inks are considered.

• The KSFM Journal of Fluid Machinery
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• v.20 no.2
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• pp.41-46
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• 2017

The flotation performance of the induced gas flotation (IGF) machine is considerably influenced by geometric configurations of rotor and stator. The interaction of rotor and stator, which are the most important components in IGF, serves to mix the air bubbles. Thus, the understanding of flow characteristics and consequential analysis on the machine are essential for the optimal design of IGF. In this study, two-phase (water and air) flow characteristics in the forced-air mechanically stirred Dorr-Oliver flotation cell was investigated using ANSYS CFX. In addition, the void fraction and the velocity distributions are determined and presented with different blade configurations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.2
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• pp.153-161
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• 1998

This study describes the results of the analysis of measured rotating stall signal in a centrifugal compressor with vaneless diffuser. Unsteady flow and rotating stall in vaneless diffuser were investigated by measuring of unsteady velocity fluctuation using hot-wire anemometer. Experiments were carried out in several impeller rotating speeds, at different radius ratios. Single hot -wire was used to study the characteristics of rotating stall. As a result, the abrupt rotating stall was detected at all measured impeller rotating speeds and the several flow coefficients which are less than 0.16. The number of the stall cell was one at all measured rotational speeds, and the rotating direction was the same as that of the impeller. As the flow rate decreased, the profile of the phase averaged radial velocity component with time changed from a sawtooth to a sine wave.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.495-498
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• 1994

Genistein, a inhibitor of the progression of G$_{1}$ and G$_{2}$ phase of the mammalian cell cycle, was discovered through a unique screening system, in which effects of microbial metabolites on the cycle progression of the cultured mouse mammalian carcinoma cell were monitored by flow cytometry. The inhibitor was extracted from the fermentation broth of Streptomyces sp. ZF10 with ethyl acetate, and purified by silica gel column chromatography and HPLC.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.2
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• pp.201-210
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• 1996

Predictive tests for the identification of contact sensitizing chemicals have been developed. We measured the sensitization potential with three predictive tests, the in vitro and the in vivo Local Lymph Node Assay(LLNA), ELISA to detect interferon-gamma(IFN-${\gamma}$) from supernatant and flow cytometry to detect change of cell surface proteins, using draining lymph nodes of mice. BALB/c mice were exposed to various chemicals or vehicles on the ears daily for 3 consecutive days in all experiments. With some exceptions of propyl paraben, neomycin sulfate, the in vivo LLNA was able to detect the sensitizing capacity of test chemicals and was more sensitive than the in vitro LLNA for chemicals used in the present study. In another experiment, contact sensitivity was assessed by the ELISA to detect IFN-Υ from the supernatants of the cultured LNCs after sensitization with chemicals. There was a good correlation between the LLNA and the IFN-Υ production for test chemicals. We also examined the change of cell surface proteins on LNCs after sensitization by flow cytometry for some cell adhesion molecules(ICAM-1, E-cadherine, B7 molecule), T cell markers(CD3, CD4, CD8, T$\alpha$$\beta$,T${\gamma}$$\delta$) and B cell markers(LR1, CD45R, I-Ad). The number of ICAM-1 positive cells and B cells in LNCs were increased after sensitization with DNCB, TNCB, isoeugenol and 25%, 50% cinnamic aldehyde compared with that of vehicle as a control. In conclusion, the in vivo LLNA could provide more sensitive screening test for moderate to strong sensitizers and some weak sensitizers including cosmetic raw materials than the in vitro LLNA. The production of IFN-Υ by allergen-activated LNCs might be a values indicators without radioisotopes for the identification of contact allergens. Detection of allergens by testing the increase of ICAM-1 positive cells and B cells in LNCs by flow cytometry might be used as a test method to detect allergens.

• Atmosphere
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• v.26 no.1
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• pp.159-183
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• 2016

On 31 July 2014, there was a localized torrential rainfall ($58.5mm\;hr^{-1}$) caused by a strong convective cell with thunder showers over Daegwallyeong. In the surface synoptic chart, a typhoon was positioned in the East China Sea and the subtropical high was expanded to the Korean peninsula. A WRF (Weather Research and Forecasting) numerical simulation with a resolution of 1 km was performed for a detailed analysis. The simulation result showed a similar pattern in a reflectivity distribution particularly over the Gangwon-do region, compared with the radar reflectivity. According to the results of the WRF simulation, the process and mechanism of the localized heavy rainfall over Daegwallyeong are as follows: (1) a convective instability over the middle part of the Korean peninsula was enhanced due to the low level advection of warm and humid air from the North Pacific high. (2) There was easterly flow from the coast to the mountainous regions around Daegwallyeong, which was generated by the differential heating of the insolation among Daegwallyeong and the Yeongdong coastal plain, and nearby coastal waters. (3) In addition, westerly flow from the western part of Daegwallyeong caused a strong convergence in this region, generating a strong upward motion combined by an orographic effect. (4) This brought about a new convective cell over Daegwallyeong. And this cell was more developed by the outflow from another thunderstorm cell to the south, and finally these two cells were merged to develop as a strong convective cell with thunder showers, leading to the record breaking maximum rainfall per hour ($58.5mm\;hr^{-1}$) in July.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.4
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• pp.316-322
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• 2012

A fuel cell vehicle has the hydrogen detection sensors for checking the hydrogen leakage because it use hydrogen for its fuel and can't use a odorant to protect the fuel cell stack. To verify the hydrogen safety of leakage we select the high possible leak points of fittings in hydrogen storage system and test the leaking behavior at them. The hydrogen leakage flow rate is 10, 40, 118 NL/min and the criterion for maximum hydrogen leakage is based on allowing an equivalent release of combustion energy as permitted by gasoline vehicles in FMVSS301. There are total 18EA hydrogen leakage detection sensors installed in test system. we acquire the hydrogen leakage detection time and determine the ranking. Hydrogen leakage detection time decrease when hydrogen leakage flow rate increase. The minimum hydrogen leakage detection time is about 3 seconds when the flow rate is 118NL/min. In this study, we optimize hydrogen sensor position in fuel cell vehicle and verify the hydrogen leakage safety because there is no inflow inside the vehicle.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.28 no.1
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• pp.59-71
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• 1998

The radiation-induced apoptosis was studied for two human cancer cell lines (KB cells, RPMI 2650 cells) and the human gingival fibroblast cell line (HGF-1 cells). The single irradiation of 2, 10, 20Gy was done with 241.5 cGylmin dose rate using the /sup 137/Cs MK cell irradiator. The cells were stained with propidium iodide and examined under the fluoro-microscope and assayed with the flow cytometry a day after irradiation. Also, the LDH assay was done to determine the amount of necrotic cells. The obtained results were as follows: 1. On the fluoro-microscope, many fragmented nuclei were detected in the KB, RPMI 2650, and HGF-1 cells after irradiation. 2. On the DNA content histogram obtained from the flow cytometry, the percentages of the pre-Gl peak of the control and 2, 10 and 20Gy irradiation group were 4.5, 55.0, 52.3, and 66.6％ on KB cells, 2.7, 3.3, 31.8, and 32.6％ on RPMI 2650 cells and 2.8, 21.8, 30.4, and 40.2％ on HGF-1 cells respectively. 3. The number of Gl-stage cells was abruptly decreased after 2Gy irradiation on KB cells and 10Gy irradiation on RPMI 2650 cells, But there was a slight decrease without regard to irradiation dose on HGF-1 cells. 4. There was no significantly different absorbance in extracellular LDH assay along the experimental cell lines.