• Journal of the Korean Vacuum Society
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• v.18 no.3
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• pp.208-212
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• 2009

The optical characterization of self-assembled InAs/AlAs quantum dots(QD) grown by MBE were investigated using photoreflectance spectroscopy. The intensities of the signals of the GaAs buffer and wetting layer(WL) changed with the width of the WL layer. The PR spectrum for the sample, in which QDs layer were etched off at room temperature, indicated that the broadened signal ranging $1.1{\sim}1.4\;eV$ was originated from InAs QDs and WL. The intensities of signals of GaAs buffer and the WL changed with the WL width. A red shift of the PR peak of WL are observed when the annealing temperatures range from $450^{\circ}C$ to $750^{\circ}C$, which indicates that the interdiffusion between dots and capping layer is caused by improvement in size uniformity of QDs.

• Korean Journal of Medicinal Crop Science
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• v.14 no.2
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• pp.70-76
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• 2006

Paeoniae radix has been widely used for its anti-allergic, anti-inflammatory and analgesic effects, and demonstrated to have anticonvulsant, memory enhancing and anxiolytic activities. The present study was performed to examine the protective effect of methanol extract of Paeoniae radix (PR) from Paeoniae Japonica Miyabe et Takeda (Paeoniaceae) on hydrogen peroxide $(H_2O_2)-induced$ neurotoxicity using cultured rat cerebral cortical neuron. $H_2O_2$ produced a concentration-dependent reduction of neuronal viability, PR, over a concentration range of 10 to $100\;{\mu}g/ml$ showed concentration-dependent decrease of the $H_2O_2$$(100\;{\mu}M)-induced$ neuronal cell death, as assessed by a 3-[4,5-dimethylthiazol-2-yl]-2,5-di-phenyl-tetrazolium bromide assay and the number of apoptotic nuclei, evidenced by Hoechst 33342 staining. PR $(100\;{\mu}g/ml$ inhibited $100\;{\mu}M$ $H_2O_2-induced$ elevation of the cytosolic $Ca^{2+}$ concentration $([Ca^{2+}]_c)$, which was measured by a fluorescent dye, flue-4 AM. PR $(50\;{\mu}g/ml$ inhibited glutamate release into medium induced by $100\;{\mu}M$ $H_2O_2$, which was measured by HPLC, and generation of reactive oxygen species (ROS). These results suggest that PR may mitigate the $H_2O_2-induced$ neurotoxiciy by interfering with the increase of $[Ca^{2+}]_c$, and then inhibiting glutamate release and generation of ROS in cultured neurons.

• Journal of Physiology & Pathology in Korean Medicine
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• v.18 no.2
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• pp.522-527
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• 2004

The aim of this study is to investigate the effect of Naegwan-Acupuncture stimulation on the relationship of change in electrocardiopgraphy(EGG). For this purpose, 11 normal volunteers were acupunctured at Naegwan acupoint using the method of Young-Su-Bo-Sa. Then, we measured and observed the change of augmented unipolar limb leads aVR, aVL and aVF in EGG. In aVR, Naegwan acupuncture treated groups were increased the activity of PR interval and PR segment compared to the control group. In aVL, Naegwan acupuncture treated groups were increased the activity of R wave amplitude, PR interval and PR segment. In aVF, Naegwan acupuncture treated groups were increased the activity of S wave amplitude and PR interval. These results suggested that Naegwan acupuncture stimulation play an important role to the activities of EGG.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.11
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• pp.450-457
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• 2016

While many studies on the heat transfer effect of an impinging jet have been published, most studies focus on the downward impinging jet. This study investigates the impinging jet heat transfer phenomenon when water at a temperature of $24^{\circ}C$ impinges on the downward isothermal circular plate at 60, 70, and $80^{\circ}C$ and when the upward round jet nozzle is 4, 6, and 8 mm diameter with a flow rate 3.6, 4.6, and 5.6 L/min, respectively, and when the ratio of the nozzle clearance/nozzle diameter (H/D) is 1. The results showed that, as the nozzle diameter decreases, the heat transfer coefficient increases at a constant flow rate. The correlation equation of $Nu_r$, $Pr_r$, and $Re_{jg}$ is obtained in the impinging and constant velocity flow region $(Nu_r/Pr^{0.4}_r)Dr=4.6[Re_{jg}(r/R_c)Dr]^{0.8}$ at all flow rates, in the deceleration and falling flow regions $(Nu_r/Pr^{0.4}_r)Dr=42.7{\mid}Re_{jg}(r/R_c)Dr-345.7{\mid}^{0.3}$ at 3.6 L/min, $(Nu_r/Pr^{0.4}_r)Dr=92.4{\mid}Re_{jg}(r/R_c)Dr-16.8{\mid}^{0.2}$ at 4.6 L/min, and $(Nu_r/Pr^{0.4}_r)Dr=322.4{\mid}Re_{jg}(r/R_c)Dr-536.2{\mid}^{0.01}$ at 5.6 L/min.

• Journal of the Korean Vacuum Society
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• v.9 no.2
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• pp.130-135
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• 2000

We have analyzed characteristics for the structure of $Al_{0.25}/Ga_{0.75}/As/In_{0.15}/Ga_{0.85}$/AS/GaAS pseudomorphic high electron mobility transistor (PHEMT) by photoluminescence (PL) and photoreflectance (PR) measurements. By the PL measurement at 10 K, we observed el-hl transition peak at 1.322 eV and e2-hl transition peak at 1.397 eV in the InGaAs quantum well. We calculated value of 23 meV, the difference between the first energy level and the second energy level of a valence band by dependence of temperatures. Also, (e2-h2) transition signal was observed at 300 K by PR measurement. From the PR measurement, we recognized that the transition was dominated the second energy level of conduction band than the first energy level of conduction band due to band filling. The other hand, PL signal of the first energy level of conduction band was dominated because of the electron screening effect.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.92-96
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• 2001

The present study was investigated effect of each water extract from Pueraria flos (PF) and Pueraria radix (PR) on serum several biomarkers in ethanol-treated rats. Male Sprague-Dawley rats were randomly divided into six groups: Normal (None-treated group); Ethanol (only ethanol-treated group); EPF I (ethanol-treated, supplemented group); EPR (ethanol-treated, PF II-supplemented group); EPR I (ethanol-treated, PR I-supplemented group) ; EPR (ethanoltreated, PR II-supplemented grou). Five groups of male Sprague-Dawley rats were orally administered 25% ethanol (5 g/kg body weight/day) and sacrified 5 weeks post treatment. Aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and ${\gamma}-glutamyl$ transpeptidase activities were significiantly lowered by feeding of PF or PR than those of only ethanol-treated group. Whereas serum glucoseand liver glycogen contents were significantly decreased (p<0.05) by ethanol administration and increased decreased (p<0.05) by PF or PR supplement. This results indicate that Pueraria flos and radix water extract supplement improves alcoholic disorder.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.640-646
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• 2001

The electrical stability for DC stress of Pr$_{6}$O$_{11}$-based ZnO varistos consisting of ZnO-Pr$_{6}$O$_{11}$-CoO-Cr$_2$O$_3$-Er$_2$O$_3$-based ceramics were investigated with sintering temperature in the range of 1325~1345$^{\circ}C$. A the sintering temperature is raised, the nonlinear exponent of varistors was decreased, whereas the stability was markedly improved. The density of ceramics was found to greatly affect the electrical stability for DC stress. The varistors sintered at 13$25^{\circ}C$ were completely degraded because of thermal runaway attributing to low density. The varistors sintered at 1335$^{\circ}C$ exhibited the highest nonlinearity, with a nonlinear exponent of 70.53 and a leakage current of 1.92$\mu$A, whereas they did not exhibit relatively high stability. On the contrary, the varistors sintered at >134$0^{\circ}C$ exhibited not only a high nonlinearity marking the nonlinear exponent above 50 and the leakage current below 3$\mu$A, but also a high stability marking the variation rate of the varistor voltage below 2%, even under DC stress such as (0.80V$_{1mA}$/9$0^{\circ}C$/12h)+(0.85V$_{1mA}$/115$^{\circ}C$/12h)+(0.90V$_{1mA}$/12$0^{\circ}C$/12h)+(0.95V$_{1mA}$/1$25^{\circ}C$/12h)+(0.95V$_{1mA}$/15$0^{\circ}C$/12h). In particular, ti was found that the varistors sintered at 134$0^{\circ}C$ were more nonlinear and more stable, compared with that of 1345$^{\circ}C$.EX>.}C$.EX>.

• Clean Technology
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• v.17 no.4
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• pp.300-305
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• 2011

A mixture of supercritical carbon dioxide and a co-solvent was employed to strip a high-dose ion-implanted photoresist (HDIPR) from the surface of semiconductor wafers. The stripping efficiency was highly improved by the physical force generated from a ultrasonication tip inside the reactor. In addition, helium gas was injected in the reactor as a barrier gas before the introduction of pure supercritical $CO_2$ ($scCO_2$), which reduced the rinsing time significantly. The effect of co-solvents on the stripping efficiency was investigated. The wafer surfaces were analyzed by scanning electron microscopy and by an energy dispersive X-ray spectrometer.

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.189-195
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• 2019

In this work, the flow and combustion characteristics using a 3-D numerical simulation was evaluated for a shale gas fueled combustor in a commercial class gas turbine. The Standard k-e turbulence model, 2 step methane oxidation mechanism, Finite rate/Eddy dissipation reaction model, DTRM radiation model were employed and validated well at the baseline condition (Natural Gas, Pilot Ratio 0.2). Based on the validated models, the combustion characteristics of shale gas was evaluated for three pilot ratios cases. It was found that NOx concentrations for all shale gas cases were less than the that for city gas, which imply that, at the selected PRs, the condition for combustion stability is satisfied. In addition, for higher PR, whereas the average temperatures at the exit are the same, the NOx increases. It means that diffusion combustion portion increases due to the higher PR.

• Clinics in Shoulder and Elbow
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• v.25 no.1
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• pp.5-14
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• 2022

Background: The purpose of this study was to verify the effect of protocatechuic acid (PCA) on tendon healing and fatty degeneration in a chronic rotator cuff model. Methods: Twenty-eight Sprague-Dawley male rats were randomly allocated into two groups: Saline+repair (SR) and PCA+repair (PR). The right shoulder was used for experimental interventions, and the left served as a control. PCA (30 mg/kg/day) was administered intraperitoneally at the site of infraspinatus tendon detachment in rats in the PR group, and the same volume of saline was administered to the same site in the SR group. The torn tendon was repaired 4 weeks after infraspinatus detachment. Four weeks after repair, hematoxylin and eosin (H&E), S100, and CD68 stains were performed to evaluate the degree of fatty degeneration and H&E and Masson trichrome stains were performed to assess tendon healing. Superoxide dismutase (SOD) was measured to test the efficacy of PCA as an antioxidant. Results: Results from histological evaluation indicated that SOD and CD68 levels at the musculotendinous region and collagen fiber parallel to the orientation at the tendon-to-bone junction were not significantly different between the SR and PR groups. The mean load-to-failure of the PR group (20.32±9.37 N) was higher than that of the SR group (16.44±6.90 N), although this difference was not statistically significant (p=0.395). The SOD activity in the operative side infraspinatus muscle of the PR group was higher than that of the SR group, but the difference was not statistically significant (p=0.053). Conclusions: The use of PCA could improve tendon healing and decrease fatty degeneration after rotator cuff repair.