• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.5
• /
• pp.77-82
• /
• 2003

A parametric study was conducted on pressure drop in a catalytic converter for automobile. In this work, we proposed a new pressure drop relation which contains the various parameters needed to calculate and got a few results. In a monolith of catalyst, the flow originally turbulent flow changes to laminar flow and thus the pressure drop through the monolith is linearly proportional to the velocity. The exhaust pressure is doubly affected by the increase of mean velocity and length when we decrease the diameter of monolith while the volume keeps constant. Theoretical parameters such as $\alpha$ and $\beta$ are suggested to use as a reference value when there is no a experimental data. Especially in the part load test, these values should be modified to consider the property change of exhaust gas.

• Journal of Ginseng Research
• /
• v.19 no.2
• /
• pp.122-126
• /
• 1995

The effects of treating bovine heart mitochondria with potassium chloride and surfactants such as digitonin and n-dodecy-$\beta$-maltoside (DMS) including plant saponins on extracting cytochrome c were examined. The spectra given by the cytochrome c-containing solutions from the extraction were inspected to ascertain whether ginseng and bellflower saponins could be used instead of the generally- employed surfactants of digitonin and DMS. These studies implied that the effect of ginseng saponins is superior to that of digitonin but inferior to that of DMS, and give rise to the idea of substitutional property of ginseng saponins for the widely-employed surfactants in the extraction of mitochondria intermembrane cytochrome c. The substitution for the solubilizing surfactants by bellflower saponins could, however, not presumably be anticipated; while ginseng saponin mixture are a suitable substitute.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.202.2-202.2
• /
• 2003

A bioassay-guided fractionation of the whole extract of Viscum album (a parasitic plant : Loranthaceae) led to the isolation of two triterpenoidal components, oleanolic acid (1), ${\beta}$-amyrin acetate (2), homoflavoyadorinin B (3) as well as large quantity of free fatty acid mixtures as active ingredients of the extract responsible for the antitumoral property. The EtOAc soluble part and BuOH soluble part of the extract demonstrated a significant inhibition on the proliferation of cultured human tumor cells such as A549 (non small cell lung), SK-OV-3 (ovary), SK-MEL-2 (melanoma), XF498 (central nerve system) and HCT-15 (colon) in vitro, whereas the remaining water soluble part exhibited a poor inhibition. (omitted)

• The Journal of Korean Medicine
• /
• v.26 no.3 s.63
• /
• pp.204-214
• /
• 2005

Objectives : The verity extract of the Gagam-Hyungbang-Gihwang-tang (GHG) was assessed to determine the mechanisms of its antioxidant activity. Methods : The fellowing effects were measured : GHG exhibited a concentration-treatment; scavenging ${\alpha},\;{\alpha}-diphenyl-\beta-picrylhydrazyl$ (DPPH) radical, linoleic acid oxidation in a thiocyanate assay system, and superoxide anion, hydroxyl radical-induced DNA nicking. We investigated mRNA levels such as superoxide-dismutase. Results : The GHG extract showed dose-dependent free radical scavenging activity, including DPPH radicals, hydroxyl radicals, and superoxide anion, using different systems. The GHG was also found to be effective in protecting plasmid DNA against the strand breakage induced by hydroxyl radicals in Fenton's reaction mixture. Furthermore, SOD-1 mRNA expression levels increased in tat hepatoma H4IIE cells Conclusions : We expect that GHG will to helpful to the development of antioxidant activity treatments.

• Journal of Microbiology and Biotechnology
• /
• v.18 no.9
• /
• pp.1572-1577
• /
• 2008

A facultative dissimilatory metal-reducing bacterium, Shewanella sp. strain HN-41, was used to produce magnetite nanoparticles from a precursor, poorly crystalline iron-oxyhydroxide akaganeite ($\beta$-FeOOH), by reducing Fe(III). The diameter of the biogenic magnetite nanoparticles ranged from 26 nm to 38 nm, characterized by dynamic light scattering spectrophotometry. The magnetite nanoparticles consisted of mostly uniformly shaped spheres, which were identified by electron microscopy. The magnetometry revealed the superparamagnetic property of the magnetic nanoparticles. The atomic structure of the biogenic magnetite, which was determined by extended X-ray absorption fine structure spectroscopic analysis, showed similar atomic structural parameters, such as atomic distances and coordinations, to typical magnetite mineral.

• Journal of Powder Materials
• /
• v.6 no.1
• /
• pp.111-118
• /
• 1999

Ni(Fe)Al powders containing a homogeneous distribution of the in-situ formed AIN and $Al_2O_3$ dispersoids have been produced by mechanical alloying process in a controlled atmosphere using high energy attrition mill. The powders have been successfully consolidated by hot extrusion process. The phase information investigated by TEM and XRD analysis reveals that Fe can be soluble up to 20% to the NiAl phase ($\beta$) at room temperature after MA process. Subsequent thermomechanical treatment under specific condition has been tried to induce secondary recrystallization (SRx) to improve high temperature properties, however, the clear evidence of SRx was not obtained in this material. Mechanical properties in term of strength at room temperature as well as at high temperatures have been improved by the addition pf AIN, and the room temperature ductility has been shown to be improved after heat treatment, presumably due to the precipitation of second phase of $\alpha$ in this material.

• IE interfaces
• /
• v.16 no.spc
• /
• pp.39-44
• /
• 2003

As one of many design variables, the role of dimension tolerances is to restrict the amount of size variation in a manufactured feature while ensuring functionality. In this study, a nonlinear integer model has been modeled to allocate the optimal tolerance to each individual feature at a minimum manufacturing cost. While a normal distribution determines statistically worst tolerances with its symmetrical property in many previous tolerance allocation studies, a asymmetrical distribution is more realistic because its mean is not always coincident with a process center. A nonlinear integer model is modeled to allocate the optimal tolerance to a feature based on a beta distribution at a minimum total cost. The total cost as a function of tolerances is defined by machining cost and quality loss. After the convexity of manufacturing cost is checked by the Hessian matrix, the model is solved by the Complex Method. Finally, a numerical example is presented demonstrating successful model implementation for a nonlinear design case.

• The Bulletin of The Korean Astronomical Society
• /
• v.36 no.1
• /
• pp.51.1-51.1
• /
• 2011

Red dusty Active Galactic Nuclei (AGNs) are suspected to mid-stage between ULIRG and AGN phase. As well as, red AGNs are suspected that they have more than 50% of whole AGN population. In order to understand the character of red AGNs, Black Hole (BH) mass of red AGN is a key property and can not measured by existing method such as reverberation mapping and single epoch method. Thus we still don't know their character and properties in clearly. To estimate properties of red AGNs without the effect of dust-obscuration, we have obtained Near InfraRed (NIR) spectra of 31 reverberation mapped AGNs and 49 Palomar-Green(PG) Quasi-Stellar Object (QSO) by using the infrared camera (IRC) for AKARI with unique wavelength range $2.5-5.0{\mu}m$. From this spectra, we measured the FWHM and luminosity of brackett ${\alpha}$ and ${\beta}$ at 4.0, 2.6 micron meter for deriving new BH mass estimators based on the properties of Brackett line emission.

• Journal of Life Science
• /
• v.14 no.1
• /
• pp.14-16
• /
• 2004

Various ligands function as regulators in the allosteric control of tryptophan synthase. Effects of the monovalent cations and glycerophosphate on the mutant tryptophan synthases were examined in the presence of L-serine. The results showed that these compounds might play roles in the allosteric control of the proteins.

• The Bulletin of The Korean Astronomical Society
• /
• v.37 no.1
• /
• pp.51.2-51.2
• /
• 2012

Red Active Galactic Nuclei (AGNs) are suspected to intermediate stage between ULIRG and AGN phase. As well as, red AGNs are suspected to have more than 50% of whole AGN population. For understanding the characteristics of red AGN, Black Hole (BH) mass is a key property and can not be estimated by existed method such as reverberation mapping and single epoch method using 5100A continuum and Balmer lines. Thus we still don't know their characteristics and properties in clearly. To estimate properties of red AGNs without the effect of dust extinction, we obtained Near InfraRed (NIR) spectra of 31 reverberation mapped AGNs and 49 Palomar-Green(PG) Quasi-Stellar Objects (QSOs) by using the infrared camera (IRC) of AKARI space telescope with unique wavelength range 2.5-5.0 ${\mu}m$. Upon this spectra, we measured the FWHM and luminosity of Brackett ${\alpha}$ and ${\beta}$ lines for deriving new BH mass estimators of AGNs.