• Journal of Powder Materials
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• v.12 no.3
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• pp.214-219
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• 2005

In order to investigate the formation of AlN, mechanical alloying was carried out in $N_2$ and $NH_3$ atmosphere. Differential thermal analysis (DTA), x-ray diffraction (XRD) and chemical analysis were carried out to examine the formation behavior of aluminum nitrides. No diffraction pattern of AlN was observed in XRD analysis of the as-milled powders in $NH_3\;or\;N_2$ atmosphere. However, DTA and chemical analysis indicated that the precursors for AlN were formed in the Al powders milled in $NH_3$ atmosphere. The AlN precursors transformed to AlN after heat treatment at and above $600^{\circ}C$. It was considered that the reaction between Al and $NH_3$ was possible by the formation of fresh Al surface during mechanical alloying of Al powders.

• Journal of the Korean Ceramic Society
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• v.26 no.6
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• pp.811-819
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• 1989

There have been many studies on the biological phenomena of Bioglasses, which nay be used as implant materials in human body. However, not many works on the Bioglass compositions have been reported. In the present study, the effect of Al2O3 substitution for SiO2 in Bioglass of Na2O-CaO-P2O5-SiO2 system on its structure and properties was examined. Infrared and Raman spectroscopic studies for the glass structural analysis, differential thermal analysis and X-ray diffraction analysis for crystallization of the glass were perfomed. Several physical properties, such as thermal expansion coefficient, softening point, microhardness and reaction phenomena, were also measured. The major crystalline phase, after heat treatment of the glasses, was Na2Ca2(SiO2)3 and the crystal was transformed into other phase with increased substitution of Al2O3. The added Al2O3 reduced non-bridging oxygen in glass structure and thermal expansion coefficient, but increased glass density, sofening point and microhardness. When the glasses are reacted in Tris-buffer solution, the substituted Al2O3 inhibited the formation of hydroxyapatite on the Bioglas surface, and no hydroxyapatite was formed for the sample which contained more than 6wt.% of Al2O3 even if they were reacted for 600 hours.

• Korean Journal of Metals and Materials
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• v.49 no.1
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• pp.46-51
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• 2011

Real-time formation of $L1_0$ phase of FePt nanoparticles in the gas phase during ultrasonic-spray pyrolysis is first discussed in the present study. Without any post heat treatment, $L1_0$ phase of FePt nanoparticles appeared at the temperature above $900^{\circ}C$ in the gas phase synthesis. X-ray diffractometry (XRD) and transmission electron microscopy (TEM) studies revealed that FePt nanoparticles less than 10 nm in size contained small volume of $L1_0$ fct phase. However, in other samples obtained at the temperature below $900^{\circ}C$, iron oxide phase co-existed and no evidence of phase transformation was found. Thus, it is anticipated that the time of flight of particles required for crystallization and phase transformation was extended according to the increase of the collision rate. Finally, magnetic properties represented by coercivity and saturation magnetization and functional groups on the particle surface were discussed based on VSM and FT-IR results.

• The Journal of the Korea Contents Association
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• v.12 no.5
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• pp.303-310
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• 2012

In radiotherapy, accurate patient positioning and set up are important factor that treatment can influence success. In generally, the 3-laser system is used when the patient set up. But today the body surface scanning system(C-Rad system) is trying to use. Compare and evaluate the C-Rad system and the 3-laser system to check availability. Head and neck that are no movement of internal organs and easy to apply fixation device are limited. Alderson Rando anthropomorphic phantom and 10 patients who have lesions of head and neck are targeted. C-RAD system's setup error mean and standard deviation are the X axis($0.55{\pm}0.51mm$), Y axis($-0.2mm{\pm}0.523mm$), Z axis($-0.85{\pm}0.587mm$) in the phantom study, and in the patient study X axis($-0.05{\pm}0.621mm$), Y axis($0.075{\pm}0.755mm$) Z axis($-1.025{\pm}0.617mm$). So C-RAD system is better than 3-laser system mostly, but C-RAD system's error rate is a little worse than 3-laser system in the Z axis. When radiation treatment of head and neck, body surface contour scanning system contribute to correct positioning and minimize the set up error.

• Journal of Conservation Science
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• v.29 no.2
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• pp.93-102
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• 2013

The wooden Ksitigarbha Triad Statues (Treasure No. 1749) of Shinhungsa temple in Sokcho are enshrined in the inside of the Myeonbujeon Hall. The Statues are highly damaged physical weathering which are crack and exfoliation. Also, the Statues were deteriorated by chemical and biological weathering. This study carried out nondestructive method as deterioration map, ultrasonic measurement, X-ray and endoscopy survey for deterioration evaluation and conservation plan. As a result, Ksitigarbha Statue coated by dust and various pollutants. And gold-gilt of Statue's surface has peeled off. Head part of Mudokguiwang Statue was discolored from water leak in Myeongbujeon Hall. Domyeongjonja Statue is highly damaged by insects. Result of endoscopy, there were bee hives in the inside of the Statue. Therefore, we suggest that these Statues have need to do conservation treatment on the basis of diagnostic results.

• Restorative Dentistry and Endodontics
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• v.15 no.1
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• pp.201-216
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• 1990

A variety of surface pre-treatments have been advocated to prepare the dentin prior to placement of a bonding agent. The purpose of this study was to evaluate the effect of various dentin conditioners upon the degree of resin impregnation to the dentinal tubules and the shear bond strength of a new dentinal bonding agent (Scotchbond 2) used in conjunction with a visible light cured composite (Silux). The healthy eighty human molars extracted due to periodontal or orthodontic reasons were used and randomly divided into five groups. All the grinded dentin surfaces were conditioned with 3% $H_2O_2$, Cavity Cleanser (Columbus/Bayer), Dentin Conditioner (GC Inter. Corp.), Scotchprep (3M Co.) according to the manufacturer's directions. The specimens were then demineralized in 10% HCl for 20 sec. and 24 hrs. in order to observe the resin tags in Hitachi X-450 scanning electron microscope at 25KV. Also, shear strengths were obtained using an Instron Testing Machine with a cross head speed of 1 mm/min. The following results were obtained ; 1. In group treating with Dentin Conditioner and Scotchprep, the resin strings were formed on most of the surfaces and penetrated more than $50{\mu}m$ into the tubules. 2. The inner surface of resin treated with Cavity Cleanser, indicating the resin strings formed partly and penetrated about in depth of $30{\mu}m$. 3. In control and experimental group treated with 3% $H_2O_2$, the resin tags were not formed, if any, penetrated shortly. 4. Shear bond strengths in groups treating with Dentin Conditioner and Scotchprep were statistically significant increase than with 3% $H_2O_2$. (P<0.01). 5. The Scotchprep treatment group was significantly higher in shear strength than groups treated with no conditioning and Cavity Cleanser.(P<0.01) 6. Shear bond strengths evaluated were gradually increase in proportion to the tag length of resin impregnation.

• Korean Journal of Materials Research
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• v.17 no.8
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• pp.437-441
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• 2007

Preparation and morphology control of $TiO_2$ nano powders for gas sensor applications are investigated. $TiO_2$ nanopowders with rutile and anatase structures were prepared by controlling the pH value of a precursor solution without any heat treatment. The mean particle size of $TiO_2$ powders were below 10nm. The prepared $TiO_2$ nano powders were hydrothermal treated by NaOH solution. The sample was washed in HCl solution. As a result and $TiO_2$ nanotubes were formed. The lengths of $TiO_2$ nanotube were $1{\mu}m$ and the diameters were 10nm. Crystal structure and microstructure of $TiO_2$ nanotube were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). As-prepared $TiO_2$ nanotube powders have several advantages of nano particle size and high surface area and could be a prominent candidate for nano-sensors. The sensitivity of $TiO_2$ nanotube sensor was measured for toluene and NO in this study.

• Archives of Craniofacial Surgery
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• v.17 no.3
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• pp.162-164
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• 2016

Stafne bone cavity is a rare mandibular defect that was first reported by Edward C. Stafne in 1942. It commonly presents with a well-demarcated, asymptomatic, unilateral radiolucency that indicates lingual invagination of the cortical bone. A 52-year-old female patient who with nasal bone fracture, visited the hospital. During facial bone computed tomography (CT) for facial area evaluation, a well-shaped cystic lesion was accidentally detected on the right side of the mandible. Compared to the left side, no swelling or deformity was observed in the right side of the oral lesion, and no signs of deformity caused by mucosal inflammation. 3D CT scans, and mandible series x-rays were performed, which showed a well-ossified radiolucent oval lesion. Axial CT image revealed a cortical defect containing soft tissue lesion, which has similar density as the submandibular gland on the lingual surface of the mandible. The fact that Stafne cavity is completely surrounded by the bone is the evidence to support the hypothesis that embryonic salivary gland is entrapped by the bone. In most cases, Stafne bone cavity does not require surgical treatment. We believe that the mechanical pressure from the salivary gland could have caused the defect.

• Journal of dental hygiene science
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• v.16 no.3
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• pp.235-241
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• 2016

This study was conducted to provide basic understanding regarding possible enamel erosion by three kinds of fist-aid antipyretic and analgesic medicines over a period of time, with comparison and analysis of the resulting deciduous teeth surface and microhardness changes. The analysis was performed using energy dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM) to examine the surface erosion and changes. The Kruskal-Wallis test show differences in surface erosion and changes after 3, 5 and 8 days of treatment as well as before and after the treatment in each group. According to the results, there was no significant difference in the early deciduous teeth enamel surface microhardness (p>0.01). However there were signigicant changes after 3, 5, and 8 days (p<0.01). Calcim (Ca) and phosphorous (P) analysis using EDX showed significant differences in the enamel characteristics according to each tissue area after 8 days (p<0.05), but there was no significant difference in any of the areas for P content (p>0.05). In the surface observation with the SEM treatment with Children's Tylenol$^{(R)}$ tablet, which has the lowest pH, looked the roughest, followed by Brufen syrup for children and Children's Tylenol$^{(R)}$ suspension. Based on these results, it should be considered that antipyretic and analgesic medicines for children, which have lower pH values, may cause tooth erosion. Hence, it is necessary to give special attention to oral hygiene in young children or infants by brushing their teeth after such drugs are administered.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.163-174
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• 1996

The purpose of this study was to examine the effects of bisphosphonate and indomethacin, blockers of bone resorption with different mechanisms, on alveolar bone remodeling. Male rats were divided into control, bisphosphonate and indomethacin groups, and then each group was divided info an experimental side and a control side according to the force application. Bisphosphonate(6.3mg/kg,$2.52x10^{-2}mol/L$) and indomethacin (9mg/kg, $2.52x10^{-2}mol/L$) were injected 6 hours and 1 hour before or 24 hours after the force application. The rats were killed 72 hours after the force application and histologic examination was perfomed. The values of serum acid phosphatase and lactate dehydrogenase were also measured in the control md experimental groups treated with bisphosphonate or indomethacin 1 hour before the force application. In the experimental side, the least number of osteoclasts was noted in the groups treated 1 hour before the force application with indomethacin or bisphosphonate, while there were no differences between the control and the groups treated with drugs 6 hours before or 24 hours after the force application. In the control side, the number of osteoclasts was not inecreased with no differences among the groups. Histologic examination revealed a severe alveolar bone resorption in the control group and the groups treated with indomethacin 6 hours before or 24 hours after the force application. Indomethacin treatment 1 hour before the force application and bisphosphonate treatment at any time significantly attenuated the bone resorption. Electron microscopically, ruffled border and clear zone of osteoclasts were observed in the control and indomethacin groups, while some osteoclasts were detached from the bone surface and exhibited dull cellular projections in the bisphosphonate groups. The bisphosphonate and indomethacin groups showed lower values of acid phosphatase and lactate dehydrogenase than the control group. The acid phosphatase value in the bisphosphonate group was lower than that in the indomethacin group, whereas there was no difference in the lactate dehydrogenase value between the groups. These results suggest that bisphosphonate reduces the activity of osteoclasts as well as the number of osteoclasts and that indomethacin reduces the number of osteoclasts without affecting the activity of osteoclasts. Bisphosphonate has a larger inhibitory effect on bone resorption md thus less limitation in the application time than indomethacin.