• Restorative Dentistry and Endodontics
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• v.34 no.5
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• pp.424-429
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• 2009

This study aimed to assess the influence of different cross-sectional area on the cyclic fatigue fracture of Ni-Ti rotary files using a fatigue tester incorporating cyclical axial movement. Six brands of Ni-Ti rotary files (ISO 30 size with. 04 taper) of 10 each were tested: Alpha system (KOMET), HeroShaper (MicroMega), K3 (SybronEndo), Mtwo (VDW), NRT (Mani), and ProFile (Dentsply). A fatigue-tester (Denbotix) was designed to allow cyclic tension and compressive stress on the tip of the instrument. Each file was mounted on a torque controlled motor (Aseptico) using a 1:20 reduction contra-angle and was rotated at 300 rpm with a continuous, 6 mm axial oscillating motion inside an artificial steel canal. The canal had a $60^{\circ}$ angle and a 5 mm radius of curvature. Instrument fracture was visually detected and the time until fracture was recorded by a digital stop watch. The data were analyzed statistically. Fractographic analysis of all fractured surfaces was performed to determine the fracture modes using a scanning electron microscope. Cross-sectional area at 3 mm from the tip of 3 unused Ni-Ti instruments for each group was calculated using Image-Pro Plus (Imagej 1.34n, NIH). Results showed that NRT and ProFile had significantly longer time to fracture compared to the other groups (p < .05). The cross-sectional area was not significantly associated with fatigue resistance. Fractographycally, all fractured surfaces demonstrated a combination of ductile and brittle fracture. In conclusion, there was no significant relationship between fatigue resistance and the cross-sectional area of Ni-Ti instruments under experimental conditions.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.9
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• pp.3945-3949
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• 2015

Background: For brachytherapy of cervical cancer, applicator shifts can not be avoided. The present investigation concerned Utrecht interstitial applicator shifts and their effects on organ movement and DVH parameters during 3D CT-based HDR brachytherapy of cervical cancer. Materials and Methods: After the applicator being implanted, CT imaging was achieved for oncologist contouring CTVhr, CTVir, and OAR, including bladder, rectum, sigmoid colon and small intestines. After the treatment, CT imaging was repeated to determine applicator shifts and OARs movements. Two CT images were matched by pelvic structures. In both imaging results, we defined the tandem by the tip and the base as the marker point, and evaluated applicator shift, including X, Y and Z. Based on the repeated CT imaging, oncologist contoured the target volume and OARs again. We combined the treatment plan with the repeated CT imaging and evaluated the change range for the doses of CTVhr D90, D2cc of OARs. Results: The average applicator shift was -0.16 mm to 0.10 mm for X, 1.49 mm to 2.14 mm for Y, and 1.9 mm to 2.3 mm for Z. The change of average physical doses and EQD2 values in Gy${\alpha}/{\beta}$ range for CTVhr D90 decreased by 2.55 % and 3.5 %, bladder D2cc decreased by 5.94 % and 8.77 %, rectum D2cc decreased by 2.94 % and 4 %, sigmoid colon D2cc decreased by 3.38 % and 3.72 %, and small intestines D2cc increased by 3.72 % and 10.94 %. Conclusions: Applicator shifts and DVH parameter changes induced the total dose inaccurately and could not be ignored. The doses of target volume and OARs varied inevitably.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.77-77
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• 2000

Titanium oxide (TiO2) thin films have valuable properties such as a high refractive index, excellent transmittance in the visible and near-IR frequency, and high chemical stability. Therefore it is extensively used in anti-reflection coating, sensor, and photocatalysis as electrical and optical applications. Specially, TiO2 have a high dielectric constant of 180 along the c axis and 90 along the a axis, so it is highlighted in fabricating dielectric capacitors in micro electronic devices. A variety of methods have been used to produce patterned self-assembled monolayers (SAMs), including microcontact printing ($\mu$CP), UV-photolithotgraphy, e-beam lithography, scanned-probe based micro-machining, and atom-lithography. Above all, thin film fabrication on $\mu$CP modified surface is a potentially low-cost, high-throughput method, because it does not require expensive photolithographic equipment, and it produce micrometer scale patterns in thin film materials. The patterned SAMs were used as thin resists, to transfer patterns onto thin films either by chemical etching or by selective deposition. In this study, we deposited TiO2 thin films on Si (1000 substrateds using titanium (IV) isopropoxide ([Ti(O(C3H7)4)] ; TIP as a single molecular precursor at deposition temperature in the range of 300-$700^{\circ}C$ without any carrier and bubbler gas. Crack-free, highly oriented TiO2 polycrystalline thin films with anatase phase and stoichimetric ratio of Ti and O were successfully deposited on Si(100) at temperature as low as 50$0^{\circ}C$. XRD and TED data showed that below 50$0^{\circ}C$, the TiO2 thin films were dominantly grown on Si(100) surfaces in the [211] direction, whereas with increasing the deposition temperature to $700^{\circ}C$, the main films growth direction was changed to be [200]. Two distinct growth behaviors were observed from the Arhenius plots. In addition to deposition of THe TiO2 thin films on Si(100) substrates, patterning of TiO2 thin films was also performed at grown temperature in the range of 300-50$0^{\circ}C$ by MOCVD onto the Si(100) substrates of which surface was modified by organic thin film template. The organic thin film of SAm is obtained by the $\mu$CP method. Alpha-step profile and optical microscope images showed that the boundaries between SAMs areas and selectively deposited TiO2 thin film areas are very definite and sharp. Capacitance - Voltage measurements made on TiO2 films gave a dielectric constant of 29, suggesting a possibility of electronic material applications.

• Applied Biological Chemistry
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• v.15 no.1
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• pp.49-57
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• 1972

Varietal difference in root distribution and other root characteristics were investigated under fold and water culture condition. The results were as follows: 1. IR667 showed funnel type of root distribution in soil profit while Jinheung had barrel type, and each type appearance was more distinguishable with fertilizer application. 2. Root weight per tiller was smaller in IR667 than in Jinheung and IR667 had more root in 0 to 5cm of soil depth but Jinheung had more in 5 to l0cm depth. 3. Horizontal distribution of root was dencer near to stem base without fertilizer than with fertilizer in both IR667 and Jinheung indicating structural construction for intensive nutrient uptake. Between varieties this 'dence to stem base' trend accompaning 'dence to wide spacing side' was greater in IR667 without fertilizer and these were quite true with fertilizer in Jinheung. 4. The decreasing rates of root and ear weight by fertilizer application were greater in IR667 than in Jinheung. This and other characteristics indicated that the root of IR667 is likely to be panicle-number type comparing with Jinheung. 5. The root of IR667 had lower oxidizing power of ${\alpha}-naphthylamine$ than that of Jinheung indicating weaker resistance to reductive soil but cation exchange capacity of water-cultured root was higher in IR667 suggesting stronger nutrient uptake. 6. The content of phosphorus and especially potassium in root were higher with fertilizer but lower without fertilizer in IR667 than in Jinheung indicating that IR667 is more sensitive to root environment. 7. The contents of N, K and CEC were increasing toward root tip while P content was decreasing. The root from surface soil had higher N and K content than that from subsoil. The contents of N,P,K, and CEC of root at harvesting stage were about 1.0%, 0.1%, 0.5% and 15me/100g at dry weight base, respectively.

• Journal of Korean Society of Forest Science
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• v.82 no.1
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• pp.26-33
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• 1993

In vitro shoot proliferation and rooting were tested for 2-0 seedlings of half-sib families of 4 plus oaks trees. Nodal segments having axillary buds from 37 families(16 of Quercus acutissima, 10 of Q. variabilis, 7 of Q. serrata, and 4 of Q. mongolica) were cultured on WPM(Woody Plant Medium) supplemented with 0.5 mg/l BA (6-benzyladenine) and 0.01 mg/l NAA(${\alpha}$-naphthalene acetic acid) and subcultured at 2-3 weeks of intervals fur 6 months. In vitro rooting was carried out on GD(Gresshoff and Doy) medium supplemented with 0.5mg/l IBA(indole butyric acid). The capacity for shoot proliferation and rooting was highly varied with families. Generally, white oaks(Q. serrata and Q. mongolica) showed poor response than black oaks(Q. acutissima and Q, variabilis) in shoot proliferation and rooting. Among the total of 37 families, 7 of Q. acutissima, each 2 of Q. variabilis, Q. serrata, and Q. mongolica revealed abilities for continuous shoot proliferation, and the others failed to proliferate. Rooting of the selected oak trees also greatly varied among the families. In Q. acutissima, rooting ratio ranged from 10.0%(CB 25. KG 4) to 89.8%(CB 18). Although 26.7% of KG 16 in Q. variabilis, 3.3% of JN 15 in Q. serrata were rooted, Q. mongolica was not rooted at all in this experimental conditions. No relationship between shoot growth and the rooting ability was observed. Present results suggest the possibility of large-scale micropropagation, but further studies on family differences, shoot-tip necrosis, and callusing of rooting junction are still required to develop reliable micropropagation systems.