• Journal of Korea Foundry Society
• /
• 제17권5호
• /
• pp.488-493
• /
• 1997

주방상태 및 열처리를 행한 다합금계백주철(Fe-5%Cr-5%V-5%Mo-5%W-X%C(X=0.5, 1.0, 1.5, 2.0, 2.5, 3.0)에 있어서 탄소함량이 탄화물의 형태 및 잔류오스테나이트의 함량에 미치는 영향에 관하여 연구하였다. 주방상태의 경우, 2.0% 이하의 탄소함량에서는 편상MC 및 층상 $M_2C$탄화물만 관찰되었으나 2.5%C 이상의 경우, 편상 및 괴상MC, 층상$M_2C$ 그리고 셀형 $M_7C_3$탄화물이 관찰되었다. 또한, 기지조직내 오스테나이트의 함량도 탄소첨가와 더불어 점차 증가하여 2.5%C에서 84.8%의 최대함량을 나타낸 후, 3.0%C에서는 다시 감소하였다. 또한 열처리한 시편의 경우, 1차탄화물의 형상은 주방상태의 그것과 비슷하였으나 열처리중 기지조직내 용해되었던 C, Cr, V, Mo, W등이 아주 미세한 2차탄화물의 형태로 석출되어 기지조직내 오스테나이트의 함량은 주방상태의 그것에 비해 감소하였다.

• Journal of Nutrition and Health
• /
• 제34권7호
• /
• pp.754-761
• /
• 2001

Effects of dietary fatty acids and vitamin E on antioxidant vitamin status were studied in rat brain sections. Sources of dietary fat(10t%) were safflower oil(SO) poor in $\omega$3 fatty acid and mixed oil (MO) with computer-adjustd fatty acid ratios(AA/DHA=1.4, $\omega$6/$\omega$3=6.3, P/M/S=1.0/1.5/1, AA=2.%)with (ME) and without(MO) vitamin E(500mg/kg diet). Rats were fed the three kinds of diet from 3-4 wks prior to the conception. At the age of 3 & 9wks of the 2nd generation rat, antioxidant vitamins were measured in frontal cortex(FC), corpus striatum (CS), cerebellum(CB) and hippocampus(HP) using a multiwavelength, reverse phase gradient HPLC system. The levels of antioxidant vitamins converged to the similar value in all groups at 9 wks of age. Retinol, lycopene and cryptoxanthin levels of all experimental groups were found to be the highest in hippocampus at both 3 & 9wks of age. The levels of vitamin E appeared to be higher in the order of HP>CS-CB>FC in MO & ME. Beta-carotene and retinol showed the lowest level in hippocampus of vitamin E supplemented groups, even though vitamin E level tended to be higher in other sections. It seemed that vitamin E has an inhibitory action on the uptake of beta-carotene or acts as a preferred antioxidant to beta-carotene in certain section of the brain. By improving fatty acid balance (AA/DHA = 1.4, $\omega$6/$\omega$3=6.3, P/M/S=1.0/1.5/1, AA = 2%), the levels of vitamin E, retinol, lycopene & beta=carotene tended to be higher in MO than in SO, although crytoxanthin became lower at 3wks of age. In short, dietary fatty acids and vitamin E have different influence on antioxidant vitamin status in different rat brain sections. The higher levels of antioxidant vitamins in hippocampus should be pursued further in relation to behavioral development of rats.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• 제20권9호
• /
• pp.2819-2832
• /
• 1996

The estimation of the remaining life for the aged components in power plant as well as chemical and petroleum plants has been recently concerned. The raw materials used in this study are the 1Cr-1Mo-0.25V steel which intensified P and S compositions along with the nominal compositions of ASTM A 470 standard. Five kinds of specimens with the different degradation levels were prepared by isothermal aging heat treatment at 630.deg.C. The mechanical properties and rotated bending fatigue strength of virgin and aged 1Cr-1Mo-0.25V steel have been investigated through the hardness, tensile, fatigue test, SEM fractograph and EDS analysis at 538.deg.C and room temperature, respectively. Thus the data of aged specimens were compared with those of virgin specimen to evaluate the aging effects. The main results obtained in this study are as follows ; The decrease of the yield and tensile strength due to degradation was distinguished until 50, 000hrs simulated service time. And it was confirmed that the considerable amount of P, Mn, Cr and S was precipitated at the grain boundary of aged material through the SEM and EDS analysis. The rotated bendingd fatigue strength at 538.deg.C of virgin, 25, 000, 50, 000, 75, 000 and 100, 000 hrs aged material was decreased 44.6 %, 49.6 %, 51.5 %, 52.4% and 53.8% than that of virgin material at 10$_{7}$cycles of room temperature, respectively. The major cracks of virgin and aged materials mainly initiated at the inclusions including Si, P and Mn compositions which were located at the outer periphery of the specimen.n.

• Korean Journal of Clinical Laboratory Science
• /
• 제42권3호
• /
• pp.116-124
• /
• 2010

This study was aimed to clerify the cytotoxicity of some plant extracts such as Hosta longissima HONDA (HL), Hemerocallis fulva var. Kwanso REGL (HFVK), Hemerocallis fulva L (HF), Macrocapium officinale NAKAI (MO) and Mentha canadensis var. piperascens HARA (MCVP), the cultured NIH3T3 fibroblasts were treated with 25, 50, 100, 150 and $200{\mu}g/mL$ of five kinds of plant extracts for 48 hours, respectively. The cytotoxicity of plant extracts was measured by MTT and NR assays for the cell viability, and XTT assay for the cell adhesion activity. In this study, HL, MO and FHVK extracts showed the range of midtoxic-non toxic by the criteria of chemical cytotoxicity. While, the HF and MCVP extracts showed midtoxic. In the extract cytotoxicity, HL, MO and FHVK extracts showed non-toxic by the criteria of extract cytotoxicity. While, HF extract was determined as lower-toxic. In the responsive sensitivity of each plant extract on colorimetric assays, HF extract was sensitive to mitochondrial enzyme by MTT assay, lysosomal enzyme by NR assay and mitochondrial nucleus by XTT assay. While, MCVP extract was sensitive to mitochondrial enzyme by MTT assay and lysosomal enzyme by NR assay than other assays. While, HL, HFVK and MO extracts were most sensitive to NR assay. Cell culture is one of useful materials in the screening of cytotoxic and recovary effect on the putative chemical agents or plant extract. And also, colorimetric assay is regarded as very useful tools for quantitative measurement of cytotoxic effect on plant extracts in vitro.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• 제46권4호
• /
• pp.21-27
• /
• 2009

In this work, Er-silicided SB-SOI nMOSFET and Pt-silicided SB-SOI pMOSFET have been fabricated to investigate the current-voltage characteristics of Schottky barrier SOI nMOS and pMOS at elevated temperature. The dominant current transport mechanism of SB nMOS and pMOS is discussed using the measurement results of the temperature dependence of drain current with gate voltages. It is observed that the drain current increases with the increase of operating temperature at low gate voltage due to the increase of thermal emission and tunneling current. But the drain current is decreased at high gate voltage due to the decrease of the drift current. It is observed that the ON/Off current ratio is decreased due to the increased tunneling current from the drain to channel region although the ON current is increased at elevated temperature. The threshold voltage variation with temperature is smaller and the subthreshold swing is larger in SB-SOI nMOS and pMOS than in SOI devices or in bulk MOSFETs.

• Journal of Korea Foundry Society
• /
• 제20권4호
• /
• pp.240-246
• /
• 2000

Surface layer properties such as composition, phase, hardness, and oxide layer condition are very important if the main failure mechanism of metals is wear. Generally, stable and dense oxide layers are known to decrease the wear rate of metals by prohibition of metallic junction occurred between bare metals. Addition of Si above 4 wt% to DCI(Ductile Cast Iron) is reported to enhance the significant oxidation resistance by forming the silicon-rich surface layer which inhibits further oxidation. And addition of up to 2 wt% Mo to high Si ductile iron produces significant increases in high temperature tensile strength, creep strength, thermal fatigue resistance and oxidation resistance. High pressure wear characteristics of unalloyed DCI(Ductile cast Iron), 4.46 wt% Si ductile iron, 4.3 wt% Si-0.52 wt% Mo ductile iron were investigated through unlubricated pin-on-disc wear test. Wear test was carried out at speed of 23m/min, under pressure of 3 MPa and 3.3 MPa. Wear surfaces of each specimen were observed by SEM to determine the wear mechanism under high pressure wear condition. Addition of Si 4.46 wt% severely deteriorated wear property of ductile iron compared to unalloyed DCI. But combined addition of Si 4.3 wt%andMo0.52wt%decreasedthefrictioncoefficient(${\mu}$)ofductileironsandremarkablydelayedthemild-severeweartransition.

• Journal of the Korean institute of surface engineering
• /
• 제49권1호
• /
• pp.81-86
• /
• 2016

$Eu^{3+}$-doped $MgMoO_4$ phosphor thin films were deposited on quartz substrates by radio frequency magnetron sputtering with changing various growth temperatures. The effects of growth temperature on the structure, transmittance, optical band gap, and luminescence of the phosphor thin films were characterized. All the phosphor thin films, irrespective of growth temperature, showed a monoclinic structure with a main (220) diffraction peak. The thin film deposited at a growth temperature of $400^{\circ}C$ indicated an average transmittance of 90% in the wavelength range of 500 ~ 1100 nm and band gap energy of 4.81 eV. The excitation spectra of the phosphor thin films consisted of a broad charge transfer band peaked at 284 nm in the range of 230 ~ 330 nm and two weak peaks located at 368 and 461 nm, respectively. The emission spectra under ultraviolet excitation at 284 nm exhibited a sharp emission peak at 614 nm and several weak bands. All the phosphor thin films showed high asymmetry ratio values, indicating that $Eu^{3+}$ ions incorporated into the host lattice occupied at the non-inversion symmetry sites. The results suggest that the growth temperature plays an important role in growing high-quality phosphor thin films.

• Journal of Physiology & Pathology in Korean Medicine
• /
• 제27권3호
• /
• pp.327-330
• /
• 2013

The purpose of this study is to report a clinical progress of treatment of sequelae caused by removal of facial schwannoma through Korean medicine. A patient was diagnosed with facial schwannoma by MRI on 4th June 2012 in local university hospital, he had right facial palsy, auditory hypersensitivity, dizziness after removal of facial schwannoma. Between 25th July 2012 and 26th January 2013, he was treated with acupuncture, cupping, electro-acupuncture every week and observed by House-Brackmann facial nerve grading system(H-B scale) and MoReSS every month. He had 29 times treatments. At the first of treatment, his state was Grade IV (H-B scale), 4/8(facial nerve grading), 10 points during action 7 points during rest(MoReSS) and he had severe facial palsy, ill-acrimation, auditory hypersensitivity. At the middle of treatment, October 2012, symptoms improved. State was Grade III (H-B scale), 5/8(facial nerve grading), 7 points during action 3 points during rest(MoReSS). Severe facial palsy improved ; Forehead creasing and union motor function recovered, he was able to close his eyes so ill-acrimation improved. At the end of treatment, January 2012, state was Grade II (H-B scale), 7.5/8(facial nerve grading), 3 points during action 1 point during rest(MoReSS). He had only occasional tinnitus and auditory hypersensitivity. Acupuncture and electro-acupuncture are estimated to be good for facial palsy after removal of facial schwannoma. More cases are required to develop treatment of facial palsy.

• Journal of the Korean Institute of Gas
• /
• 제2권4호
• /
• pp.42-46
• /
• 1998

Miniaturized specimen technology Permits mechanical behavior to be determined using a minimum volume of material. The technology is useful in case of not collecting a large amount of materials from industrial equipments. Five kinds of accelerated degradation materials were prepared by isothermal aging heat treatment at $630^{\circ}C$. Three kinds of specimens were prepared for impact testing. In order to increase plastic constraint of subsize specimen, side-groove was introduced. Results between subsize and full size impact testing were compared. Size effects correlations were developed for the impact properties of turbine rotor material. These correlations successfully predict the ductile brittle transition temperature (DBTT) of full size Charpy impact specimens based on subsize specimen data.

• The Korean Journal of Applied Statistics
• /
• 제25권6호
• /
• pp.1037-1047
• /
• 2012

The generalized linear mixed model(GLMM) is widely used in fitting categorical responses of clustered data. In the numerical approximation of likelihood function the normality is assumed for the random effects distribution; subsequently, the commercial statistical packages also routinely fit GLMM under this normality assumption. We may also encounter departures from the distributional assumption on the response variable. It would be interesting to investigate the impact on the estimates of parameters under misspecification of distributions; however, there has been limited researche on these topics. We study the sensitivity or robustness of the maximum likelihood estimators(MLEs) of GLMM for counts data when the true underlying distribution is normal, gamma, exponential, and a mixture of two normal distributions. We also consider the effects on the MLEs when we fit Poisson-normal GLMM whereas the outcomes are generated from the negative binomial distribution with overdispersion. Through a small scale Monte Carlo study we check the empirical coverage probabilities of parameters and biases of MLEs of GLMM.