• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.1038-1043
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• 1997

To adapt the neural network proess for the purpose of determination of optimal utting onditions (optimal cutting speed and feed rate), some selection strategies for the machining factors are necessary, which is considered planning cutting process. In this case, factors that have both nonlinearity and strong relationship must be selected. Although tool grade and chemical properties of workpiece material have strong effect to cutting speed, it's not easy to find a analytic relation between them. In this paper, a mathematical method for determining the optimal amount of cutting (depth of cut, feed rate) is presented by tool goemetry and heat generation during cutting process. And various tool grade and workpiece material groups ase classified based on its chemical properties. Thier chemical composition and hardness are used as input pattern for neural network learnig. The result of learning shows the relationship between tool grade and workpiece material and it is proved that it can be used as a sub-system for automatic process planning system.

• Journal of Life Science
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• v.12 no.5
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• pp.549-554
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• 2002

Taraxacunf mongofieum Hand-Mass aqua-acupuncture solution (TMAS) was prepared and investigated og, the effect on initiation of carcinogenesis. The following effe.Is as a blocking agent were measured. .(a) Indu.ction of quinone reductase, (b) Induction of glutathione S-transferase activity (c) Increase of reduced glutathione. TMAS was potent inducer of quinone reductase in Hepa Iclc7 murine hepatoma cells. Clutathione S-transferase activity was increased with TMAS. In addition glutathione levels were increased about 1.6-fold with TMAS in cultured murine hepatoma Hepa Iclc7 cells.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.6
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• pp.97-101
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• 1999

We propose and demonstrate a novel sensor which can simultaneously measure strain and temperature. The sensor is composed of a single fiber Bragg grating and an erbium-doped fiber amplifier. Using linear variation in the amplified spontaneous emission power of an erbium-doped fiber amplifier with temperature, we determine the temperature. By subtracting the temperature effect from the Bragg wavelength shift, we determine the strain. Experiments show rms deviations of $18.2{\mu}{\varepsilon}$ and $0.7^{\circ}C$ for strain and temperature, respectively.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.179-183
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• 2007

A plate heat exchanger (PHE) normally uses vacuum brazing technology for connecting plates and fins. However, the reliability of high temperature brazing, especially with nickel-based filler metals containing boron the formation of brittle intermetallic compounds (IMCs) in brazed joints is of major concern. since they considerably degrade the mechanical properties. This research was examined the vacuum brazing of commercially SUS304 stainless steel with BNi-2 (Ni-Cr-B-Si) filler metal, and discussed to determine the influence of brazing temperatures on the microstructure and mechanical strength of brazed joints. In the metallographic analysis it is observed that considerable large area of Cr-B intermetallic compound phases at the brazing layer and the brazing tensile strength is related to removal of this brittle phase greatly. The mechanical properties of brazing layer could be stabilized through increasing the brazing temperature over $100^{\circ}C$ more than melting temperature of filler metals, and diffusing enough the brittle intermetallic compound formed in the brazing layer to the base metal.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.142-146
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• 2007

Vacuum brazing method has been coming to an important process as one of the new fabricating techniques of metals and alloys. In this study, a vacuum brazing of SUS304 stainless steel with BNi-2 filler metal was carried out in $1{\times}10^{4}$ Torr of vacuum atmosphere. The formation of brittle intermetallic compounds in brazed joints between SUS304 stainless steel and BNi-2 filler metal is a major concern, since they considerably degrade the mechanical properties of joints. To obtain enough stable joining strength, it is necessary to understand the unique properties of brazing process with Ni-based filler metals containing boron. So, in this research we investigated the performance of SUS304/BNi-2 brazed system and the brazed joint properties were evaluated at room temperature by using tensile test. Metallurgical and fractographic analysis were used to characterize the microstructure, the mechanisms of brazing, and joint failure modes.

• KSBB Journal
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• v.11 no.1
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• pp.52-57
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• 1996

Bovine aortic smooth muscle cells cultured on the slide glass were exposed to sheared flow up to 120 hours in flow chamber to see the effect of shear stress on cell growth in wall shear stresses of 0 to 26dyn/$cm^2$. From lactate dehydrogenase concentration measurement of the circulating medium, it was shown that sheared flow in the shear stress range did not remove additional smooth muscle cells from the slide glass compared with cells in stationary condition. According to smooth muscle cell counting per$cm^2$ of the surface, smooth muscle cells grew fastest in the stationary condition. As the wall shear stress increased, the growth of cells became slower. When the wall shear stress increased over 17dyn/$cm^2$, cell growth was not observed throughout the experiment.

• Journal of Korean Society for Atmospheric Environment
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• v.34 no.1
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• pp.120-143
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• 2018

The analytical methods and their ambient levels of organic nitrogenous compounds such as nitrosamines, nitramines (nitroamines), imines, amides and nitro-polycyclic aromatic hydrocarbons (nitro-PAHs) in the atmosphere are summarized and discussed. Sampling for the analysis of organic nitrogenous compounds was mostly conducted using high volume air sampler. The direct liquid extraction (DLE) using sonification and the pressurized liquid extraction (PLE) using the accelerated solvent extraction (ASE) have been frequently employed for the extraction of organic nitrogenous compounds in the atmospheric samples. After extraction, clean-up via filtration and the solid phase extraction (SPE) and concentrations using nitrogen and rotary evaporator have been generally conducted but in some studies the clean-up and concentration steps have been omitted to prevent the loss of analyte and improve the recovery rate of the analytical procedure. Instrumental analysis was mainly carried out using gas chromatography (GC) or the high performance liquid chromatography (HPLC) coupled with the single quadrupole mass spectrometer or tandem mass spectrometer in the electron ionization (EI), positive chemical ionization (PCI) and negative chemical ionization (NCI) mode and analysis sensitivity of nitrosamines and nitramines were higher in NCI mode. Desirable sampling and analysis methods for analyzing particulate organic nitrogenous compounds are suggested.

• Natural Product Sciences
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• v.18 no.2
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• pp.76-82
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• 2012

Stamens of Mesua ferrea L. are a well-known herbal drug used in Indian System of Traditional Medicine to treat various diseases. The claimed activity of this plant part is necessitated to investigate antioxidant and hepatoprotective activity. Authenticated plant sample was extracted with hexane, ethanol (EtOH) and water (aq.) using ASE 100 accelerated solvent extractor. Antioxidant activity was evaluated by means of different in vitro assays. Hepatoprotective effect was investigated on carbon tetrachloride induced oxidative stress in liver slice culture model. Cytotoxic marker lactate dehydrogenase (LDH) released in culture medium and the activity of lipid peroxidation along with antioxidant enzymes (AOEs) namely superoxide dismutase (SOD), catalase (CAT) and glutathione reductase (GR) were estimated. Hexane and EtOH extracts were significantly inhibited DPPH, NO, SOD and $ABTS^+$ radical in dose dependent manner. The trade of phenol content was: aq. extract < hexane extract < EtOH extract. A significant correlation was shown by total phenol content and free radical scavenging activity of extracts. The culture system treated with hexane extract, EtOH extract or ascorbic acid exhibited significant depletion in LDH, lipid peroxidation, antioxidative enzymes SOD, CAT and GR. Hexane extract and EtOH extracts of stamen of M. ferrea protected liver slice culture cells by alleviating oxidative stress induced damage to liver cells.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.437-443
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• 2015

In this paper, we analyze the performance of the all-optical multihop radio over a free space optical (RoFSO) communication system with amplify-and-forward (AF) relays under varying weather conditions. The proposed channel model considers the propagation loss, attenuation and atmospheric fading modeled by the Gamma-Gamma (GG) distribution. Both the amplified spontaneous emission (ASE) noise in the all-optical relays and the background noise projected onto receiver apertures have been considered in the analysis. The lower bound analytical expressions for the end-to-end bit error rate (BER) and outage probability are derived for the multihop system employing the all-optical relays with the full channel state information (CSI). Meanwhile, the exact results for BER and outage probability are obtained via Monte Carlo simulation. Results indicate the performance of the proposed system will be improved by the multihop transmission technology. For a fixed number of relays, the BER and outage probability will be increased with the deterioration of the weather conditions.

• The Korean Journal of Zoology
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• v.20 no.2
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• pp.101-107
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• 1977

The effects of sodium azide, cAMP, G-strophanthin and dicumarol on the ATP-ase activity and Ca uptake of the fragmented sarcoplasmic reticulum of skeletal muscle were studied and the effects were compared with respect to the enzymatic activity and Ca transport. Sodium azide (0.05 mM) and G-strophanthin (0.25mM) caused no inhibition on either ATPase activity or Ca uptake. cAMP($1\\times10^{-6}\\sim5\\times10^{-4}$) had no effect on ATPase activity while inhibited Ca uptake. Dicumarol (0.05 mM) did not inhibit ATPase activity but caused a decreased Ca uptake of heavier fraction (8,000-12,000xG) of the reticulum fragments.