• Korean Journal of Microbiology
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• v.27 no.3
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• pp.291-296
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• 1989

Campylobacter jejuni was studied for its disinfection by heat-and cold-treatment and UV-irradiation. When C. jejuni was treated by heat, no viable cell was found after 10 min treatment at $55^{\circ}C$, whereas small fraction of cell population was survived after 60 min treatment at $45^{\circ}C$ and $50^{\circ}C$. When they were treated by cold temperature for 30 days, no cell was survived at -$23^{\circ}C$ but about 4 log of the cells were survived at both temperature of $4^{\circ}C$ and -$40^{\circ}C$. When the organisms were UV-irradiated, thier survival rates were proportionally varied to the distance of irradiation. The scanning electron microscopic studies of C. jejuni cells treated by the disinfecting agents revealed that shapes of thecells were deformed from spiral rod into spherical form. The heat-treated cells showed rough and damaged surface on the scanning electron micrographs. In the heat-treated cells, some proteins of high molecular weight appeared to become accumulated in the electrophoretic analysis. The DNAs extracted from the cells treated with the physical agents showed some differences in agarose gel electrophoresis, comparing those of normal cells.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.4
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• pp.483-489
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• 1995

To investigate the mechanism generated by irradiation in the insulator layer irradiated MIS (Metal - Insulator - Semiconductor) device, the various types of MIS capacitors depending on insulator thickness, insulator types and implanted impurities are fabricated on the P-type wafer. MIS capacitors exposed by 1Mrad Co$^{60}$ .gamma.-ray are measured for flat band voltage and charge density shifts pre- and post-irradiation. The measuring results of post-irradiation show the flat band voltage shifting toward negative direction and charge density increasing regardless of parameters. This results have a good agreement with calculated data by computer simulation. Si$_{3}$N$_{4}$ layers have a good radiation-hardness than SiO$_{2}$ layers compared to the results of post-irradiation. Also, radiation-induced negative trap is discovered in the implanted insulator layer. Using numerical analysis, four continuty equations (conduction-band electrons continuity equation, valence-band holes continuity equation, trapped electrons continuity equation, trapped holes continuity equation) are solved and charge distributions according to the distance and Si-Insulator interface states are investigated.

• Journal of Energy Engineering
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• v.13 no.4
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• pp.235-241
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• 2004

This experiment was undertaken to investigate the atomization characteristics of the high viscosity biodiesel blended fuel and ultrasonic energy irradiation one. Test fuels were conventional diesel fuel and biodiesel one. We compared to the characteristics of viscosity and surface tension, SMD between high viscosity biodiesel blended fuel and ultrasonic energy irradiation one. Sauter mean diameter was measured under the variation of the spray distance. Viscosity and surface tension were measured under the variation of the time trace. To measure the droplet size, we used the Malvern system 2600c. Droplet size distribution was analyzed from the result data of Malvern system. Through this experiment, we found that the condition of the ultrasonic energy irradiation situation had smaller Sauter mean diameter of droplet, viscosity and surface tension than those of the conventional situation.

• The Journal of Korean Physical Therapy
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• v.18 no.3
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• pp.79-87
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• 2006

Purpose: The present study purposed to examine induced characteristic or erythema and safety by medium wave ultra violet(UVB) lamp. Methods: We compared sunshine and UVB lamp using spectroradiometer and UV radiometer. For measuring sunshine irradiation, we used spectoradiometer and detected from 8 to 18 o'clock every each hour on the beach, playground and rooftop of a 5 story building. The subjects for erythema examination were 5 healthy subjects who have no pathologic history of photosensitivity reaction, psoriasis and vitiligo. They were exposed to UVB radiation at the abdominal area for 2 hours and after irradiation, we observed the change of skin color every 12 hours over a period of 1 week. Results: Between sunshine and UVB lamp, sunshine had higher data on the chromaticity coordinates, dominant and peak wavelength, bandwidth and purity than the UVB lamp but on the color temperature, brightness the UVB lamp had higher data than the sunshine. In comparison of sunshine and UVB lamp, UVB lamp irradiated constantly such as $3.9-4.4{\mu}W/cm^2$ at a distance of 100cm between bed and lamp which was same as early morning irradiation on the sunshine. The erythema didn't appear to any subject. Conclusion: This results suggest that the UVB lamp has lower irradiance as much as early sunshine. Therefore the UVB lamp had no influence of inducing erythema at a distance of 100cm between bed and lamp.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.192-194
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• 2002

We present the results on the calibration of iso-center positions using the quality assurance system established at PMRC for determination of center position in X-ray and proton irradiation fields. Details on the system are presented in another presentation in this session. The equipment in the system is mounted on a patient treatment bed in each proton exposure room, G1 or G2. A center of a stainless ball on the equipment is set at a cross of laser markers located around the iso-center and fixed on the room and on the snout in the gantry. A proton beam or an X-ray beam is exposed onto the ball through a brass collimator of 100 mm ${\times}$ 100 mm and projected onto the imaging plate set at I cm behind the ball. On the axis perpendicular to the thrust axis of the gantry on the imaging plate, a distance between a center of the collimator image and a center of the ball image varies as a cosine function of gantry angles unless the ball is set on the iso-center. An amplitude of the cosine curve shows the distance between the ball and the iso-center, an offset the offset of the collimator, and a phase shift at a zero crossing point the ball direction viewed from the iso-center. We present the relation among the iso-center position, the laser maker position, and the center of proton and X-ray irradiation fields. Its stability and its reproducibility are discussed.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1619-1624
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• 2018

Laser ablation may provide a minimally invasive palliative treatment for pancreatic cancer. The aim of the current study was to assess the feasibility of a 532-nm laser equipped with a cylindrical light diffuser for the treatment of pancreatic cancer. Monolayers of BxPC-3 human pancreatic cancer cell were exposed to 532 nm laser light. Power levels of 5 - 7 W were used to uniformly target the entire cell colonies for 60 and 120 seconds. The cells were incubated for 24 hours after treatment and viabilities were determined by using a MTT assay. Laser ablation was performed by using the cylindrical light diffuser on six pancreatic tumor tissues obtained from pancreatic cancer xenograft mouse models, which were exposed to the 532 nm light at 5W or 7W for 10 to 30 seconds. In the in vitro study, the survival rates of the pancreatic cancer cells were reduced by 6.6% to 98.9% after the treatment, and the survival rates were reduced by increasing laser power and/or irradiation time. In the pancreatic tumor tissues, a homogenous circular ablation zone was observed in all tumors and the ablation distance induced by the laser irradiation showed to be constant from the diffuser to all directions (standard deviation, 0.3 - 1.3 mm). Ablation distance and area increased with increasing laser power and/or irradiation time. The 532 nm laser effectively killed pancreatic cancer cells, and the cylindrical light diffuser was found to be suitable for laser ablation as it provided uniform ablation in pancreatic cancer.

• Food Science and Preservation
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• v.19 no.1
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• pp.47-53
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• 2012

UV light irradiation is known to give beneficial effects on fresh produce preservation. A container system equipped with UV-LED was fabricated for storing cherry tomatoes under computer-controlled conditions of intermittent on-off cycles (1 hour on/1 hour off). Wavelength (365 and 405 nm) and physical location of the LED (2 and 5 cm above fruit) were studied as variables affecting the respiration, ethylene production and quality preservation of the fruits at 10 and $20^{\circ}C$. 365 nm wavelength gave much higher radiation intensity than 405 nm, and intensity on surface decreased in inverse proportion to square of distance from LED. When compared to non-irradiated control, UV-LED irradiation decreased the respiration by 5-10% at $10^{\circ}C$ while there was no obvious effect at $20^{\circ}C$. Ethylene production was reduced when the fruits were placed at 5 cm distance, while there was no significant difference from control at 2 cm location. The reduction of ethylene production at 5 cm was more pronounced at $20^{\circ}C$. UV-LED irradiation was shown to have delayed increase or lower concentration in carotenoids compared to control treatment. Any negative effect of UV-LED irradiation on ascorbic acid content and firmness was not observed.

• Journal of Life Science
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• v.22 no.8
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• pp.1046-1051
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• 2012

In order to investigate the changes in bioactive materials induced in goldfish brains by $^{18}F$ irradiation, the variations in the neurotransmitter levels in the whole brain were studied. The distance between the goldfish and 580 mCi of $^{18}F$ was about 4 cm, and the exposure lasted for 4 hrs. The absorption level calculated based on the distance, exposure time, and half-life of $^{18}F$ was approximately 2 Gy. After sacrifice by $^{18}F$ irradiation or untreated conditions, ten brains were dissected or immediately frozen, respectively. The tissues were extracted in acetic acid. After lyophilization, the samples were dissolved in distilled water and were further purified on a reverse-phase HPLC column. There were no differences in the intensities of the bioactive materials between $^{18}F$-exposed goldfish and control goldfish, while the only peak corresponded to 13 min, which indicated a significant increase in the irradiated brains. Our analysis has found that this compound is tryptophan. This result suggests that $^{18}F$ leads to changes in a classical neurotransmitter, tryptophan, in both the brains of control goldfish and goldfish contaminated by irradiation.

• Journal of Periodontal and Implant Science
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• v.27 no.4
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• pp.819-828
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• 1997

The purpose of this study was to evaluate the abrasion-resistance of root surface after NaF iontophoresis, Nd:YAG laser irradiation and combined treatment 50 anterior teeth with flat interproximal root surface that had been extracted due to periodontal destruction were selected. All teeth were treated by the same procedure as conventional periodontal root treatment, such as scaling and root planing, root conditioning with tetracycline HCI(lOOmg/ml, 5min). The pre-treatment weight of each tooth was measured by a dial scale(SHIMADEU Co, LIBROR EB-220HU, capacity 220.000 g, Japan). All teeth were divided into 5 groups as follows: Nd:YAG laser irradiation(group 1, 1 W, 100 mJ, 10Hz, fiberoptic-root surface distance=5mm, $10\;sec.{\times}6times$, EL.EN.EN060, Italy): NaF iontophoresis(group 2, $150{\mu}A$, 4 min}: Nd:YAG laser irradiation following NaF iontophoresis(group 3): NaF iontophoresis following Nd:YAG laser irradiation(group 4): No treatment(control group). Electric toothbrushing (Oral-B, Brown Co, Germany) was conducted during 1 hour($lO\;min.{\times}6\;times$). Subsequently post-treatment weight was remeasured by the same method as pre-treatment weight measurement. The difference of abrasion rate among all groups was statistically analyzed by ANOVA(SAS program). Following results were obtained: 1. The abrasion rate was significantly lower in Nd:YAG laser irradiation group than NaF iontophoresis group(p < 0.001). 2. The abrasion rate was significantly lower in combined groups of Nd:YAG laser irradiation and NaF iontophoresis than either Nd:YAG laser irradiation group or NaF iontophoresis group(p < 0.001). 3. There was no significant difference in abrasion rate according to application order in the combined groups(p > 0.05). 4. The abrasion rate was significantly lower in all experimental groups than control group(p < 0.001). The results suggest that combined treatment of Nd:YAG laser irradiation and NaF iontophoresis on exposed root surface after periodontal therapy can enhance the abrasion-resistance of root surface and may inhibit the root caries development.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.5 s.142
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• pp.617-625
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• 2005

The purpose of this study was to develop functional and environment-friendly polyester fabric by irradiating Ultra-Violet, which was produced by the low-pressure mercury lamp. UV irradiation was conducted with various treatment times and distances. Also, pretreatments of solvents and photoinitiator were used to improve the surface modification effects. The effects of UV irradiation on the moisture regain were found to increase gradually with increase of UV treatment time and decrease of treatment distance. Compared the effects of UVC and UVA, UVC was more effective than UVA. Moisture regain and wicking of PET was increased after UV treatment in our experimental condition. And owing to increasing of moisture regain, static charge was decreased. Pretreatment of solvents such as methanol, ethyl ether and addition of photoinitiator such as Benzophenone accelerated surface modification. The moisture regain was increased but wicking was decreased with pretreatment and addition of photoinitiatior. Therefore it is considered as inappropriate f3r clothing because of wicking effects. Yellowness, tensile strength and elasticity slightly decreased after UV irradiation.