• Journal of the Korean institute of surface engineering
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• v.25 no.5
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• pp.271-281
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• 1992

Amorphous hydrogenated silicon carbide(a-Si1-xCx : H) films have been prepared by the rf sputtering using a silicon target in a gas mixture of Argon and methane with varying methane gas flow rate(fCH) in the range of 1.5 to 3.5 sccm at constant Argon flow rate of 30sccm and rf power in the range of 3 to 6 W/$\textrm{cm}^2$. The effects of methane flow rate and rf power on the structure and optical properties of a-Si1-xCx : H films have been analysed by measuring both the IR absorption spectrum and the UV transmittance for the films. With increasing the methane flow rate, the optical band gap(Eg) of a-Si1-xCx : H films increases gradually from 1.6eV to the maximum value of 2.42eV at rf power of 4 W/$\textrm{cm}^2$, which is due to an increases in C/Si ratio in the films by an significant increase in the number of C-Hn bonds. As the rf power increases, the number of Si-C and Si-Hn bonds increases rapidly with simultaneous reduction in the number of C-Hn bonds, which is associated with an increase in both degree of methane decomposition and sputtering of silicon. The effects of rf power on the Eg of films are considerably influenced by the methane flow rate. At low methane flow rate, the Eg of films decreased from 2.3eV to 1.8eV with the rf power. On the other hand, at high methane flow rate, that of films increased slowly to 2.4eV.

• Korean Journal of Veterinary Research
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• v.41 no.4
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• pp.497-503
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• 2001

Evidence from the last 10 years have been suggested that melatonin mainly produce a depressant effect on the cardiac system, but we found an activating effect of melatonin on heart rate in this research. To determine the hypothesis that melatonin has dual effects on physiological behaviour of cardiac system, we investigated the effects of melatonin on heart rate in isolated rat atria and anesthetized rats. Regardless of concentration, melatonin produced bradycardia in the 84 cases of 148 experiments (57 %) and tachycardia in the 64 cases of 148 experiments (43 %). And in atrium, melatonin produced a decrease automaticity in 52 cases of 86 experiments (60 %) and increase automaticity in 40 % (34/86 cases). Also, these effects are not significnat relationship with concetration of melatonin. The melatonin-induced bradycardia in vivo was inhibited by pretreatment of atropine or bilateral cervical vagotomy. Also, in isolated atrium the melatonin-induced decrease in automaticity was inhibited by pretreatment of atropine. These melatonin-induced responses were potenitated by pretreatment of propranolol. The melatonin-induced tachycardia in vivo was inhibited by pretreatment of propranolol, nifedipine or bilateral cervical vagotomy, but not by pretreatment of atropine. The melatonin-induced incease in automaticity in isolated atrium was converted to decrease in automaticity by pretreatment of propranolol. In addition, the change in heart rate caused by adrenoceptor agonists was inhibited by pretreatment of melatonin. These results indicate that melatonin-induced bradycardia may be related to a muscarinic receptor activation and melatonin-induced tachycardia may be related to a $\beta$-adrenoceptor stimulation.

• Ocean and Polar Research
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• v.28 no.1
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• pp.45-56
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• 2006

This study investigated primarily the toxic effects of bis(tributyltin)oxide (TBT) and DDT (Dichlorodiphenyltrichloroethane) on the mortality of adult Acartia omorii and barnacle nauplii as well as the hatching rate of A. omorii. Subsequently, compound effects of TBT and DDT on the mortality of immature copepods were tested in order to assess whether or not synergistic influence existed in the mixture of sublethal concentration of two pollutants. Mortality of adult A. omorii increased as exposure concentration of DDT increased in the range of from 0.0001 to 1ppm. Egg hatching rate of the copepod showed no distinctive difference in the range between 0.1 and 10ppm, while barnacle nauplii showed abnormal motility of their appendages in the range of 0.0001 to 1 ppm. Mortality of adult A. omorii increased as TBT concentration increased within the range of 1 and 10 ppb, whereas egg hatching rate of the copepod showed no linear response to the same exposure range. Moreover, copepod nauplii were almost motionless even though copepod eggs hatched under the exposure condition of TBT $(0{\sim}10 ppb)$ and DDT $(0{\sim}10 ppm)$, respectively, suggesting that the nauplii are hard to develop into adult stage. On the basis of the sublethal concentration less than the 24-h $LC_{50}$, 0.001 ppm (DDT) and 2 ppb (TBT) were selected to confirm the compound effects of two pollutants on the mortality of immature copepods. Mortality of immature copepods under the condition of mixture of the two pollutants was higher than that in the single exposure condition. This result seems to indicate that synergistic effects of sublethal toxicants can make a more hazardous effect on the survival of immature copepods even though the concentration of single toxicant is not lethal to copepods in the marine environment.

• Journal of Korean Academy of Nursing
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• v.36 no.2
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• pp.236-243
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• 2006

Purposes: This experimental study was designed to verify the effect of inhalation of essential oils on body weight, feed intake, food efficiency rate and serum leptin. Methods: The subjects of this study were 90 growing SD rats(46 males and 44 females). They were allocated into one of four groups, the Fennel group, Patchouli group, Bergamot group and control group. The experimental treatment was the inhalation of aromatherapy essential oils which was applied two times a day for 10 minutes each during 8 weeks. To evaluate the effects, body weight, feed intake, food efficiency rate and serum leptin were measured before and after the treatment. The collected data was analyzed by repeated measures of Kolmogorov-smirnov test and Normal Q-Q plot for nomality, Kruskal Wallis test and $X^2-test$ for experimental effects with the SPSS program. Results: The food efficiency rate was significantly lower in the Patchouli group and Fennel group than in the Bergamot group and control group(P=.000). No significant group effects were found for SD rat's body weight, feeding amount and serum leptin. Conclusion: In conclusion, these findings indicate that the inhalation of essential oils could be effective in lowering the food efficiency rate rather than the feed intake.

• Journal of the Ergonomics Society of Korea
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• v.32 no.4
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• pp.345-353
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• 2013

Objective: This research measured physiological and psychological effects of Vibroacoustic stimulation(VA) to scapular and sacrum of supine position on the mattress. Background: When vibroacoustic stimulation applies to human body, it has a positive influence on physiological and psychological effects by stimulating the organs, tissues and cells of whole body. Method: This experiment was conducted to 10 normal males in two conditions: no stimulation and vibroacoustic stimulation. No stimulation experiment was executed as a supine position for 30 minutes without any vibrational stimulus, while vibroacoustic stimulation was transmitted by the vibrational speaker, which uses 40Hz frequency. Subjects had a laser Doppler flowmeter probe in scapular, sacrum, and also had 8 channel electroencephalogram(EEG) measurement sensor in the scalp. Blood pressure and skin temperature were measured in two conditions with an underlying posture for 30 minutes. Additionally, blood flow rate and EEG were measured before and after for two minutes on two conditions. Results: According to the vibroacoustic stimulation, blood flow rate and skin temperature were increased, while blood pressure was decreased. When using vibroacoustic stimulation compared to no stimulation, blood flow rate went approximately two times higher, and skin temperature also higher 3~4 times. Furthermore, the relative alpha power of brain wave was significantly increased when we applied to vibroacoustic stimulation. Conclusion: This experiment tested the VAT embedded in mattress in two conditions. According to this experiment, VAT decreases blood pressure, improves not only a physiological effect on blood flow rate as well as skin temperature, but also psychological functions by increasing relative alpha power. Application: The results of the publishing trend analysis might help physiological and psychological effects of vibroacoustic stimulation.

• Korean Journal of Veterinary Research
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• v.42 no.1
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• pp.123-130
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• 2002

To investigate the cardiopulmonary and anesthetic effects of propofol in dogs, experimental dogs were randomly divided into 4 groups (propofol infusion anesthesia, P/INF, propofol intermittent anesthesia, P/INTER, propofol induction anesthesia, P/ISO, thiopental Na induction anesthesia, T/ISO) and monitored analgesic and anesthetic effects, recovery time, body temperature, heart rate, mean arterial pressure, respiratory rate, systolic and diastolic pressure. In all groups, apnea was not observed. In the P/INF group, the respiratory rate(RR) was slightly decreased, but in the P/INTER group, RR was increased and shallowing. In the groups of P/ISO and T/ISO, the respiratory rate was decreased. Heart rate(HR) was increased after induction anesthesia in all groups, but gradually decreased. Mean arterial pressure(MAP) was decreased after injection anesthesia in the groups of P/INF and P/INTER. In the groups of P/ISO and T/ISO, however, MAP was slightly increased. Systolic and diastolic arterial pressure were gradually decreased after induction anesthesia, but not significantly. In the groups of P/INF and P/ISO, recovery time was shorter than the groups of P/INTER and T/ISO. In all groups, body temperature of animals was decreased gradually according to time but no significant changes were observed. Propofol injection doesn't make the complete loss of responses of animals, especially, in the P/INTER group. In the P/INF group, deep pain was present until the end of anesthetic period. During recovery period, any other side effects except incoordination were not monitored. The present study suggested that infusion anesthesia was superior to intermittent anesthesia as injection anesthetic agent, and propofol was better than thiopental Na as induction anesthetic agent.

• Korean Journal of Materials Research
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• v.15 no.10
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• pp.621-625
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• 2005

Effects of rf power, pressure, sputtering gas composition, and substrate temperature on the deposition rate of the $WC_x$ coatings were investigated. The effects of rf power and sputtering gas composition on the hardness and corrosion resistance of the $WC_x$ coatings deposited by reactive sputtering were also investigated. X-ray diffraction (XRD) and Auger electron spectroscopy (AES) analyses were performed to determine the structures and compositions of the films, respectively. The hardnesses of the films were investigated using a nanoindenter, scanning electron microscopy, ana a salt-spray test, respectively. The deposition rate of the films was proportional to rf power and inversely proportional to the $CH_4$ content of $Ar/CH_4$ sputtering gas. The deposition rate linearly increased with increasing chamber pressure. The hardness of the $WC_x$ coatings Increased as rf power increased. The highest hardness was obtained at a $Ar/CH_4$ concentration of $10 vol.\%$ in the sputtering gas. The hardness of the $WC_x$ film deposited under optimal conditions was found to be much higher than that of the electroplated chromium film, although the corrosion resistance of the former was slightly lower than that of the latter.

• Korean Journal of Microbiology
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• v.20 no.1
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• pp.27-40
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• 1982

The effects of heavy metals on the growth rate and phosphate metabolism of Chlorella elliposidea cells were investigated. Chlorella cells were cultured in the media treated with Hg(0.3, 0.7, 0.9 ppm), Cd(1, 5, 15ppm), and Zn(1, 5, 50ppm) for 6days. Aliquots cells were taken out at the inoculation and at intervals during the culture, and measured packed cell vlolume and optical density. The inhibitions of heavy metals on the growth rate and chlorophyll contents were traced. Also after 6 days culture, the amounts of inorganic phosphate and organic compounds of various fractions in Chlorella cells were observed. The turbid effects of heavy metals on the growth rate and chlorphyll contents of Chlorella cells were in order of Hg>Cd>Zn. Because heavy metals depressed the biosynthesis of inorganic polyphosphates and nucleic acids and turn over of inorganic phosphates, the amounts of various phosphate compounds were decreased. The inhibitory effect of photosynthesis by heavy metals resulted in lower contents of carbohydrate. Due to the turbidity of biosynthesis of amino acids by heavy metals, contents of protein were reduced in comparison with those of control. It is suggested conciusively that the minimum concentrations affected by heavy metals on the growth rate and phosphate metabolism of Chlorella cells were 0.7 ppm Hg, 15ppm Cd, 50ppm Zn.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.41-47
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• 2003

The patency rates of small diameter vascular grafts are disappointing because of the formation of thrombus and intimal hyperplasia. Among the various factors influencing the success of graft surgery, the compliance and the size of a graft are believed to be the most important physical properties of a vascular graft. Mismatch of compliance and size between an artery and a graft alters anastomotic flow characteristics, which may affect the formation of intimal hyperplasia. Among the hemodynamic factors influencing the development of intimal hyperplasia, the wall shear stress is suspected as the most important one. The wall shear stress distributions are experimentally measured near the end-to-end anastomosis models in order to clarify the effects of compliance and diameter mismatch on the hemodynamics near the anastomosis. The effects of radial wall motion, diameter mismatch and impedance phase angle on the wall shear rate distributions near the anastomosis are considered. Compliance mismatch generates both different radial wall motion and instantaneous diameter mismatch between the arterial portion and the graft portion during a flow cycle. Mismatch in diameter seems to be affecting the wall shear rate distribution more significantly compared to radial wall motion. The impedance phase angle also affects the wall shear rate distribution.

• Korean Journal of Adult Nursing
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• v.26 no.3
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• pp.341-351
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• 2014

Purpose: The purpose of the study was to examine preventive effects of tailored water drinking on orthostatic hypotension and heart rate variability in the elderly. Methods: A non-equivalent control group pre and post time-series design was adapted. Among a total of 64 elderly people admitted to two nursing homes, 35 elderly were assigned to the experimental group and 29 were assigned to the control group. As for the elderly people in the experimental group, tailed water drink was provided according to the scheduled time for six weeks. Blood pressure and heart rate were measured twice before the intervention in both groups. The data were analyzed with SPSS program using t-test, ${\chi}^2$-test, and repeated measure of ANOVA. Results: There were significant differences in blood pressure and heart rate variability between the two groups. Conclusion: Tailored water drinking had preventive effects on decreasing blood pressure fall as well as prevalence of orthostatic hypotension in the elderly people.