• Journal of Mechanical Science and Technology
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• v.19 no.7
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• pp.1478-1487
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• 2005

A small mixed-type turbine with a diameter of 19.9 mm has been substituted for a rotational part of pencil-type air tool. Usually, a vane-type rotor is applied to the rotational part of the air tool. However, the vane-type rotor has some problems, such as friction, abrasion, and necessity of accurate assembly etc.,. These problems make the life time of the vane-type air tool short, but air tools operated by mixed-type turbines are free of friction and abrasion because the turbine rotor dose not contact with the casing. Moreover, it is assembled easily because of no axis offset. These characteristics are merits for using air tools, but loss of power is inevitable on a non-contacting type rotor due to flow loss, tip clearance loss, and profile loss etc.,. In this study, four different rotors are tested, and their characteristics are investigated by measuring the specific output power. Additionally, optimum nozzle location against the rotor is studied. Output powers are obtained through measured pressure, temperature, torque, rotational speed, and flow rate. The experimental results obtained with four different rotors show that the rotor blade shape greatly influences to the performance, and the optimum nozzle location exists near the mid span of the rotor.

• Nuclear Engineering and Technology
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• v.53 no.10
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• pp.3335-3343
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• 2021

The impact of gamma radiation on a commercial off the shelf microcontroller board has been investigated. Three different tests have been performed to ascertain the radiation tolerance of the device from a nuclear decommissioning deployment perspective. The first test analyses the effect of radiation on the output voltage of the on-board voltage regulator during irradiation. The second test evaluated the effect of gamma radiation on the voltage characteristics of analogue and digital inputs and outputs. The final test analyses the functionality of the microcontroller when using an external, shielded voltage regulator instead of the on-board voltage regulator. The results suggest that a series of latch-ups occurs in the microcontroller during irradiation, causing increased current drain which can damage the voltage regulator if it does not have short-circuit protection. The analogue to digital conversion functionality appears to be more sensitive to gamma radiation than digital and analogue output functionality. Using an external, shielded voltage regulator can prove beneficial when used for certain applications. The collected data suggests that detaching the voltage regulator can extend the lifespan of the platform up to approximately 350 Gy.

• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.131-136
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• 2018

Background: We investigated the current characteristics of a thin-film Ag electrode on a chemical vapor deposition (CVD) diamond. The CVD diamond is widely recognized as a radiation detection material because of its high tolerance against high radiation, stable response to various dose rates, and good sensitivity. Additionally, thin-film Ag has been widely used as an electrode with high electrical conductivity. Materials and Methods: Considering these properties, the thin-film Ag electrode was deposited onto CVD diamonds with varied deposition thicknesses (${\fallingdotseq}50/98/152/257nm$); subsequently, the surface thickness, surface roughness, leakage current, and photo-current were characterized. Results and Discussion: The leakage current was found to be very low, and the photo-current output signal was observed as stable for a deposited film thickness of 98 nm; at this thickness, a uniform and constant surface roughness of the deposited thin-film Ag electrode were obtained. Conclusion: We found that a CVD diamond radiation detector with a thin-film Ag electrode deposition thickness close to 100 nm exhibited minimal leakage current and yielded a highly stable output signal.

• Progress in Medical Physics
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• v.27 no.4
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• pp.224-231
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• 2016

The usefulness of Gel Bolus phantom was investigated by comparing the temperature distribution characteristic of the agar phantom produced to investigate the dose distribution characteristic of radiofrequency hyperthermia device with that of the Gel Bolus phantom under conditions similar to those of an agar phantom that can continuously carry out temperature measurement. The temperatures of the agar phantom and the Gel Bolus phantom were raised to $36.5{\pm}3^{\circ}C$ and a temperature sensing was inserted at depths of 5, 10, and 15 cm from the phantom central axis. The temperature increase rate and the coefficient of determination were analyzed while applying output powers of 100 W and 150 W, respectively, at intervals of 1 min for 60 min under conditions where the indoor temperature was in the range $24.5{\sim}27.5^{\circ}C$, humidity was 35~40%, internal cooling temperature of the electrode was $20^{\circ}C$, size of the upper electrode was 250 mm, and the size of the lower electrode was 250 mm. The coefficients of determination of 150 W output power at the depth point of 5 cm from the central axis of the phantom were analyzed to be 0.9946 and 0.9926 in the agar and Gel Bolus phantoms, respectively; moreover, the temperature change equation of the agar and Gel Bolus phantoms with time can be expressed as follows in the state the phantom temperature is raised to $36^{\circ}C:Y(G)$ is equation of Gel Bolus phantoms (in 5 cm depth) applying output power of 150 W. Y(G)=0.157X+36. It can be seen that if the temperature is measured in this case, the Gel Bolus phantom value can be converted to the measured value of the agar phantom. As a result of comparing the temperature distribution characteristics of the agar phantom of a human-body-equivalent material with those of the Gel Bolus phantom that can be continuously used, the usefulness of Gel Bolus phantom was exhibited.

• Progress in Medical Physics
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• v.30 no.1
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• pp.14-21
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• 2019

Purpose: To report the initial experience of patient-specific quality assurance (pQA) for the wobbling and line-scanning proton therapy at Samsung Medical Center. Materials and Methods: The pQA results of 89 wobbling treatments with 227 fields and 44 line-scanning treatments with 118 fields were analyzed from December 2015 to June 2016. For the wobbling method, proton range and spread-out Bragg peak (SOBP) width were verified. For the line-scanning method, output and two-dimensional dose distribution at multiple depths were verified by gamma analysis with 3%/3 mm criterion. Results: The average range difference was -0.44 mm with a standard deviation (SD) of 1.64 mm and 0.1 mm with an SD of 0.53 mm for the small and middle wobbling radii, respectively. For the line-scanning method, the output difference was within ${\pm}3%$. The gamma passing rates were over 95% with 3%/3 mm criterion for all depths. Conclusions: For the wobbling method, proton range and SOBP width were within the tolerance levels. For the line-scanning method, the output and two-dimensional dose distribution showed excellent agreement with the treatment plans.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.139-148
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• 2020

The purpose of this study is to propose a method to optimize the performance of Digital Radiography (DR) by analyzing the effect of exposure time change on the stability of radiation output and image quality. The experimental method was used to change the exposure time to 50 msec, 100 msec, 200 msec, and 400 msec so that the Percentage Average Error (PAE), Time-to-Radiation Dose Curve, Signal to Noise Ratio (SNR), Contrast to Noise Ratio (CNR) and theses analysis were performed to evaluate the normal operation of parameters, radiation output and image quality. As a result, all the parameters used in the experiment showed the Percentage Average Error in the normal range, and the shorter the exposure time, the stability of radiation output and image quality decrease. In conclusion, it was found that the performance of Digital Radiography can be optimized when stable radiation output and image quality are applied by applying 100 msec ~ 200 msec exposure time.

• Journal of Food Hygiene and Safety
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• v.7 no.2
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• pp.83-89
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• 1992

This study was perfonned to investigate effectiveness eness on the gastritis and gastric lesion with the methanol extract of the flower buds of Eugenio caryophyllata. The extract was fractionated with hexane, chIorofonn, ethyl acetate, butanol, followed by bioassay Oil antigastritis. The ethyl acetate and the buthanol fraction reduced significantly HCI.ethanol induced gastric lesion at the dose of 165 and 215 mg/kg, p.o., respectively. These results may indicate that remarkably.effective are ethyl acetate and butanol fractions in HCI-ethanol induced gastric lesion. Howeever, the fractions didn't exhibit any inhibition of gastric secretion and acid output. The buthanol fraction reduced significantly the acetic acid induced ulcer at a daily dose of 215 mg/Kg, p.o., given for 10 days. These result showed considerable inhibit of acetic acid induced ulcer without inhibition of indomethacin induced gastric lesion. The methanol extract showed low acute toxicity with minimum lethal dose of more than 3000 mg/kg, p.o. in mice. In conclusion, Eugenia F10s exhibited antigastric activity which might be attributable to inhibition of gastric secretion. It is indicated that activie component may be present in the buthanol fraction.

• Journal of radiological science and technology
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• v.33 no.2
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• pp.133-141
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• 2010

The evaluation of Varian enhanced dynamic wedges (EDW) were performed in terms of quality assurance in external radiotherapy. The seven (10, 15, 20, 25, 30, 45, 60 deg.) EDW angles were evaluated for 6 and 15 MV x-rays in Varian Linac. The STT (segmented treatment table) for a field were calculated and compared with actual movement of the jaw using Dynalog files in order to evaluate mechanical operation. Two dimensional array detector and an ionization chamber were used to measure dose distributions in phantom from Linac. The mechanical movement of jaw was agreed with its expectation and two dimensional dose distributions including beam profiles were in agreement with RTP data approximately. In comparison with RTP calculations the percentage difference of output dose values for 100 MU irradiation was less than 2.9% and measured wedge factor was less than 2.6%. These results are shown that there is no problem in clinical applications of EDW equipped on this linac.

• The Korean Journal of Physiology and Pharmacology
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• v.2 no.3
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• pp.287-295
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• 1998

Diazepam is known to have cardiovascular depressive effects through a combined action on benzodiazepinergic receptor and the GABA receptor-chloride ion channel complex. Moreover, it is known that barbiturates also have some cardiovascular regulatory effects mediated by the central GABAergic system. Therefore, this study was undertaken to delineate the regulatory actions and interactions of these systems by measuring the responses of the cardiovascular system and renal nerve activity to muscimol, diazepam and pentobarbital, administered intracerebroventricularly in rabbits. When muscimol $(0.03{\sim}0.3\;{\mu}\;g/kg)$, diazepam $(10{\sim}100\;{\mu}\;g/kg)$ and pentobarbital $(1{\sim}10\;{\mu}\;g/kg)$ were injected into the lateral ventricle of the rabbit brain, there were similar dose-dependent decreases in blood pressure (BP) and renal nerve activity (RNA). The relative potency of the three drugs in decreasing BP and RNA was muscimol ＞ pentobarbital ＞ diazepam. Muscimol and pentobarbital also decreased the heart rate in a dose-dependent manner; however, diazepam produced a trivial, dose-independent decrease in heart rate. Diazepam $(30\;{\mu}g/kg)$ augmented the effect of muscimol $(0.1\;{\mu}g/kg)$ in decreasing blood pressure and renal nerve activity, but pentobarbital $(3\;{\mu}g/kg)$ did not. Bicuculline $(0.5\;{\mu}g/kg)$, a GABAergic receptor blocker, significantly attenuated the effect of muscimol in decreasing BP and RNA, either alone or with diazepam, and that of pentobarbital in decreasing BP and RNA, either alone or with muscimol. We inferred that the central benzodiazepinergic and barbiturate systems help regulate peripheral cardiovascular function by modulating the GABAergic system, which adjusts the output of the vasomotor center and hence controls peripheral sympathetic tone. Benzodiazepines more readily modulate the GABAergic system than barbiturates.

• Journal of Veterinary Clinics
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• v.20 no.4
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• pp.449-457
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• 2003

To investigate the renal effects of enrofloxacin administration on rats induced with dehydration or hyperoxaluria, male rats were treated with enrofloxacin of 50 mg to 500 mg/kg b.w.. The microscopical observations of kidney and urine sediment were carried out in the experimental groups. The result obtained were as follows; The male rats deprived of water for 72 hours and administered with enrofloxacin. As enrofloxacin administration dose was increased, clinical signs such as loss of appetite, depression, weakness, and loss of urine output became more severe. In the histopathological findings, there were hyperemia and hemorrhage in renal cortex, vacuolation and necrosis of renal tubular epithelia, proteinous casts within renal tubules. The male rats were orally administered with sodium oxalate and injected with enrofloxacin for 7days. As enrofloxacin administration dose was increased, clinical signs such as the loss of appetite and water consumption, and weakness became more severe. In the histopathological findings, there are hemorrhage of glomeruli and cortical hyperemia, vacuolation and necrosis of tubular epithelia, proteinous casts in renal tubules. In the microscopical findings of urine sediment, there are calcium oxalate crystal (diamond-like type) and magnesium ammonium phosphate crystals (rhomboid). The male rats were intraperitoneally injected with sodium oxalate and administered with enrofloxacin for 7days. As enrofloxacin administration dose was increased, clinical signs such as the loss of appetite and water consumption, weakness were more severe. In the histopathological findings, there were hyperemia and hemorrhage in both glomeruli and renal cortex. Severe necrosis of renal tubular epithelia, bluish materials within renal tubules were also found. In the microscopical findings of urine sediment, there were many calcium oxalate crystals. The present results suggest that enrofloxacin has some injurious effects in rats having dehydration or hyperoxaluria, and clinically, we should consider these renal injury effects when we use enrofloxacin in patients accompanied renal disease, dehydration and hyperoxaluria conditions.