• The Journal of Korean Academy of Prosthodontics
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• v.36 no.6
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• pp.789-805
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• 1998

The purpose of this study was to compare the microleakage of the IPS Empress ceramic crown according to 1) margin types such as rounded shoulder and bevel, 2) margin locations such as enamel and dentine, 3) resin cement types such as Variolink and Bistite. For this study, 80 extracted premolar teeth were used. After 10 experimental dies were prepared for each group, the IPS Empress ceramic crowns were fabricated on the dies and cemented with one of two types of resin cement. After 1,000 cycles of thermal changes were given with the thermocycling unit, each specimen was sectioned with a low speed diamond saw in both the buccolingual and the mesiodistal direction. The microleakage was then measured with a stereo microscope. The obtained results were as follows : 1. Every experimental group showed microleakage. The microleakage of the crowns which had a rounded shoulder on enamel cemented with Variolink was the lowest of all. The resulting rank of the mean microleakage was rounded shoulder on enamel using Variolink(0.601mm), rounded shoulder on enamel using Bistite (0.794mm), bevel on enamel using Variolink (0.826mm), rounded shoulder on dentine using Variolink(1.054mm), bevel on enamel using Bistite(1.087mm), rounded shoulder on dentine using Bistite(1.176mm), bevel on dentine using Variolink(1.258mm), and bevel on dentine using Bistite(1.467mm). 2. The statistically significant differences in the microleakage were found in 4 cases: rounded shoulder on enamel using Variolink and bevel on dentine using Variolink, rounded shoulder on enamel using Variolink and bevel on dentine using Bistite, rounded shoulder on enamel using Bistite and bevel on dentine using Bistite, bevel on enamel using Variolink and bevel on dentine using Bistite. 3. The microleakage of rounded shoulder finish line was lower than that of bevel finish line. The statistically significant differences were found with respect to the type of finish lines. 4. The microleakage of the finish line on enamel was lower than that of finish line on dentine. The statistically significant differences were found with respect to the location of the finish lines. 5. The microleakage of the Variolink cement was lower than that of the Bistite cement. The statistically significant differences were found with respect to the resin cements.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.435-441
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• 2017

Studies on self-healing have currently been diversified and the methods to evaluate the studies have become more diversified as well. Among them, the back-scattered electron (BSE) image acquired through the scanning electron microscope (SEM) is attempted as the means to evaluate the self-healing effect on cracks. In order evaluate by the BSE image, sophisticated pre-processing of specimen is critical and this injected inside the particle, pore and artificial crack of the hardener to stabilize the structure of the newly generated self-healing product and it enables to endure the stress on polishing without deformation. The impregnated specimen smoothen the surface to obtain the BSE image of high resolution that polishing is made for diamond suspension for wet polishing after dry polishing. As a result of evaluating the self-healing product on the impregnated and polished self-healing specimen, the generated product is formed from the surface of the artificial crack and the self-healing substances are confirmed as $Ca(OH)_2$ and C-S-H.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.2
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• pp.157-170
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• 2007

Purpose: This investigation was designed to determine the translucency and color stability of various core ceramics for all-ceramic restoration using the CIE $L^*a^*b^*$ system. Material and Methods: IPS e.max Press ceramic(Ivoclar-Vivadent, Liechtenstein), $LAVA^{TM}$ All Ceramic(3M-Espe, Germany), Cercon Smart Ceramic(Dentsply, Germany), and Z-match Ceramic(DentAim, Korea) were used for this study. For the specimens of zirconia oxide ceramics, the as-sintered cylindrical blanks($11.0{\times}25.0mm$) were machined into the shape of a disk(0.4, 0.8, 1.5 mm in thickness, 10 mm in diameters) with a diamond grind machine. The IPS e.max Press specimens ($0.8{\times}10mm$) were fabricated using the "lost wax" technique. CIE $L^*a^*b^*$ coordinates and light transmission were recorded for each specimen with a spectrophotometer(CM-2600d, Minolta, Japan). Color differences were calculated using the equation, ${\Delta}E^*ab=[({\Delta}L^*)2+({\Delta}a^*)2+({\Delta}b^*)2]1/2$. Results: The results were obtained as follows: 1. The most translucent group was IPS e.max Press ceramic that is a glass-ceramic, and $Lava^{TM}$ and Z-match ceramic were more translucent than Cercon Smart ceramic in zirconia ceramic group. 2. In the all groups, there was no significant translucent change after 6 times heat-treatments required to make a final restoration. 3. Colored zirconia was showed more yellowish and dark than uncolored zirconia. 4. After heat-pressing, IPS e.max Press ceramic was showed high ${\Delta}E^*ab$ value(4.1 of eM1, 6.8 of eM2) that means to be more whiter than before heat-pressing. However, there was no color change after additive heat treatments for final restoration. 5. In the colored zirconia groups, there was no significant color change after some heat-treatments required to make a final restoration.

• Korean journal of applied entomology
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• v.48 no.1
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• pp.87-94
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• 2009

KNI3126 which is the eco-friendly material made by plant extracts - neem and matrine - have been evaluated for efficacies against 6 main pests and toxicity on natural enemies. Insecticidal efficacies of KNI3126 against plant hopper were above 95% at 5 days after treatment (DAT), whereas pesticidal effects against the cotton aphid were above 95% at 3 DAT and slightly decreased at 5 DAT. Insecticidal efficacy against the palm thrips resulted in lower control value as 68.1% than that of chemical insecticides. KNI3126 showed more than 95% control value against diamond back moth, suggesting that it could suppress the population of pest hard to control as eco-friendly material. Mortalities against two-spotted spider mite were about 80% at 1 DAT and over 90% at 5 DAT, respectively. For evaluation of the toxicity on natural enemies, effect against predatory natural enemy was classified as moderate selective toxicity based on the criterion of International Organization of Bio-Control (IOBC), whereas against parasitic natural enemies was found to be relatively safe. Repellent effect was weak against plant hopper, but strong against two-spotted spider mite. In the toxicity test for safety, KNI3126 was classified as the lowest level at acute oral, acute dermal and fish toxicity test and did not induce the irritancy at skin irritation test and eye irritation test.

• Archives of Plastic Surgery
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• v.38 no.1
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• pp.73-76
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• 2011

Purpose: Congenital midline upper lip sinus is a rare lesion. There are two postulates that can account for the formation of the upper lip sinus based on two major theories of the development of the face: the fusion theory and the merging theory. However, congenital midline lower lip sinus is very rarely reported and described. We report a case of a congenital midline sinus of the lower lip in a 6-year-old female. Methods: A 6-year-old girl presented with a nipple like swelling on the midline lower lip. Physical examination revealed about $5{\times}5$ mm protruding round mass with a just small opening that was non-tender to palpation. The mass was not associated with any skin changes. It umbilicated at the apex and contains a fistulous tract, discharging clear fluid. Only, simple radiologic finding shows bony spur on the lower one third of mandibular symphsis. Results: A small transverse ellipse is made around the opening and elevated mass with sharpe dissection. The tract is excised using the probe and dye as the guide. The tract was extended to periosteum of the lower one third of the mandible. The tract and involved periosteum were excised en bloc, and removed protrusion of the mandibular bone using diamond burr. Microscopic examination of the resected sinus revealed the fistulous tract itself, consisting of fibrous connective tissue covered with cornified stratified squamous epithelium, was observed in the center of the sample. In 6 months follow-up, This patient had a good result was obtained by the method of fistulectomy alone. Conclusion: Midline cranoifacial fistulas represent rare lesions resulting from abnormal fusion of embryologic structures. Our case report describes the excision of a congenital midline sinus of the lower lip in a 6-year-old female. This case represents the first report of a lower lip sinus presenting in a girl as a mass in the skin of the chin with extension to the midline of the mandible. However, the etiology of this rare congenital sinus remains obscure.

• Korean journal of applied entomology
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• v.54 no.1
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• pp.1-6
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• 2015

This study was conducted to estimate the economic injury level (EIL) to leaf broccoli (leaf vegetable) by the diamondback moth (Plutella xylostella L.) in 2007 and obtain basic data for pest management. To investigate the relationship between initial density of diamondback moth larvae and broccoli leaf yield, experimental plots with five treatments (0, 0.5, 1.0, 1.5 and 2.0 larvae per plant) as initial density were established. We inoculated larvae on cheesecloth covering to survey changes in larval density. When grown for consumption, leaves of broccoli are harvested in periods. High levels of larvae were associated with significant reductions in leaf yield. There were 0%, 15%, 35%, 42%, 44% yield reductions due to a density of 0, 0.5, 1.0, 1.5, 2.0 diamond back moth larvae per plant, respectively, 25 days after larva inoculation. The regression equation used to predict leaf yield based on the number of initial larvae per plant was y = 1636-394x($R^2=0.79^{***}$>). EIL of the diamondback moth on leaf broccoli was 2~3 larvae per 10 plants for a damage level of 5%. The economic threshold was 1~2 larvae per 10 plants. Thus, diamondback moth management should be initiated when 1~2 larvae appear on 10 plants.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.1
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• pp.11-18
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• 2020

High-pressure synchrotron X-ray powder diffraction experiments were performed on natural illite (K_0.65Al₂(Al_0.65Si_3.35)O₁₀(OH)₂) using diamond anvil cell (DAC) under two different pressure transmitting media (PTM), i.e., water and ME41 (methanol:ethanol = 4:1 by volume). When using water as PTM, occasional heating was applied up to about 250℃ while reaching pressure up to 2.7 GPa in order to promote both hydrostatic conditions and intercalation of water molecules into the layer. When using ME41, pressure was reached up to 6.9 GPa at room temperature. Under these conditions, illite did not show any expansion of interlayer distance or phase transitions. Pressure-volume data were used to derive bulk moduli (K₀) of 45(3) GPa under water and 51(3) GPa under ME41 PTM. indicating no difference in compressibility within the analytical error. Linear compressibilities were then calculated to be β^a = 0.0025, β^b = 0.0029, β^c = 0.0144 under ME41 PTM showing the c-axis is ca. six times more compressible than a- and b-axes. These elastic behaviors of illite were compared to muscovite, one of its structural analogues.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.6
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• pp.383-388
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• 2019

High purity SiC fine powder with metal impurity contents of less than 1 ppm was synthesized by improved carbothermal reduction process, and the synthesized powder was used for SiC single crystal growth in RF heating PVT device at temperature above 2,100℃. In-situ x-ray image analyzer was used to observe the sublimation of the powder and single crystal growth behavior during the growth process. SiC powder was used as a source of single crystal growth, exhausted from the outside of the graphite crucible at the growth temperature and left graphite residues. During the growth, the flow of raw materials was concentrated in the middle and influenced the growth behavior of SiC single crystals. This is due to the difference in temperature distribution inside the crucible due to the fine powder. After the single crystal growth was completed, the single crystal ingot was cut into a 1 mm thick single crystal substrate and finely polished using a diamond abrasive slurry. A dark yellow 4H-SiC was observed overall of single crystal substrate, and the polycrystals generated in the outer part may be caused by the incorporation of impurities such as the bubble layer mixed in the process of attaching the seed crystal to the seed holder.

• Journal of the Korean Ceramic Society
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• v.40 no.7
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• pp.657-661
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• 2003

The elastic moduli or fracture strengths of multi-layered film (SiO$_2$/po1y-Si/SiN/SiO$_2$, 2.77 $\mu\textrm{m}$ thick), CVD diamond film (1.6 $\mu\textrm{m}$ thick), SiO$_2$ film (1.0 $\mu\textrm{m}$ thick) and SiN film (0.43 $\mu\textrm{m}$ thick) made for the membrane of ink-jet printer head were measured with cantilever beam bending method using nanoindenter after fabricating in the form of micro cantilever beam (${\mu}$-CLB). And the elastic moduli of ${\mu}$-CLB of SiO$_2$ film and SiN film were compared with the value of each film on silicon substrate determined with nanoindentation method. The results showed that the modulus and strength of multi-layered film decrease from 68.08 ㎬ and 2.495 ㎬ to 56.53 ㎬ and 1.834 ㎬, respectively as the width of CLB increases from 18.5 $\mu\textrm{m}$ to 58.5 $\mu\textrm{m}$. And the elastic moduli of SiO$_2$ and SiN films measured with ${\mu}$-CLB bending method are 68.16 ㎬ and 215.45 ㎬, respectively and the elastic moduli of these films on silicon substrate measured with nanoindentation method are 98.78 ㎬ and 219.38 ㎬, respectively. These results show that with ${\mu}$-CLB bending technique, moduli can be measured to within 2%.

• Journal of the korean academy of Pediatric Dentistry
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• v.33 no.3
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• pp.422-428
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• 2006

Dentin bonding system have recently been developed in an effort to simplify and shorten bonding procedure. The intent of this study was to evaluate microleakage of newer generation of dentin bonding system comparing with other generations. Forty extracted human premolar teeth were randomly assigned to four groups for bonding : the 4th generation bonding system (Scotchbond Multi-Purpose). the 5th generation bonding system (Clearfil SE Bond), 6th generation bonding system (AQ bond) and 7th generation bonding $system(i-bond)^{TM}$ Class V cavities were prepared in buccal and lingual surface. The cavities were restored with composite resin (Z100) after the application of dentin bonding systems according to the instructions of the manufacturer Samples were thermocycled and immersed in methylene blue dye(2%). Each sample was sectioned with Isomet and evaluated for microleakage using stereomicroscopy. The mean value of the microleakage in 7th generation bonding system was greater than those of 4, 5, 6th generation dentin bonding system. Statistically, the mean values of microleakage between 4th and 7th generation bonding system were significantly different from each other (p<0.05).