• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1238-1241
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• 2000

The deformations of concrete specimens were measured at early at early ages, in order to verify the applicability of FBG(Fiber Bragg Grating) sensors. The FBG sensors were directly buried at various locations in the beam-type RC specimens at the time of fabrication. In this experiment, the changes of strains in concrete at early age were successfully measured as the movement in wavelength of light signals. The FBG sensors may be a very effective tool to investigate the mechanical/thermal behavior inside of concrete structures.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.96-104
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• 2001

This study was performed to compare the abrasiveness and wear resistance of several restorative materials occluding enamel and gold alloy. Intact labial surface of bovine incisor and the plain portion of type III gold alloy were used as plate specimens, and pin specimens were fabricated using $Artglass^{(R)},\;Targis^{(R)},\;Sculpture^{(R)}$. After two-body wear test using pin and plate model, amount of vertical height loss of plate and pin specimens were measured and statically analyzed. The amount of vertical height loss of plate specimens against pin specimens were measured by a roughness measurement instrument. The amount of vertical height loss of pin specimens against plate specimens were measured by an image analyzing program after taking scanning electron micrographs of pin specimens. The results were as following. 1. As fir the amount of enamel wear. gold group showed least amount of wear. There was no significant difference among Sculpture, Targis and Artglass groups(p<0.05). 2. As for the amount of gold wear Sculpture group standed first and Targis and Artglass group followed respectively, and there was significant difference between Sculpture and Artglass groups(p<0.05). 3. As for the amount of restorative materials against enamel, Artglass group showed greatest, and there was no significant difference among gold. Sculpture, Targis groups(p<0.05). 4. As for the amount of restorative materials against gold, Artglass group standed first and Targis and Sculpture group followed respectively, and there was significant difference among each groups(p<0.05).

• Korean Journal of Clinical Laboratory Science
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• v.41 no.4
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• pp.189-195
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• 2009

Lung cancer is a type of cancer with high mortality; its 5-year survival rate is at a low 14%. Related cytological tests include sputum, bronchial brushing, bronchial washing and fine needle aspiration cytology test etc. From the test specimens in which sputum, bronchial brushing, bronchial washing, and fine needle aspiration cytology were performed, the sensitivity, specificity and accuracy between cytology test and histology test. In the sputum test, sensitivity was 27.71% and specificity was 98.02%, and the bronchial brushing test showed sensitivity of 93.33% and a specificity of 91.3%. The bronchial washing test was a sensitivity of 53.7% and its specificity was 98.9%, and the fine needle aspiration cytology test showed sensitivity and specificity were 88.46% and 72.97%, respectively. In the specimens diagnosed as normal at the sputum test, malignant diagnosis was found in 21 specimens of bronchial brushing, 30 cases of bronchial washings and 37 cases of fine needle aspiration cytology specimens. In the specimens diagnosed as normal at the bronchial washing test, malignant diagnosis was found in 5 specimens of sputum, 7 specimens of bronchial brushin and 1 cases of fine needle aspiration cytology. One specimens found to be normal in fine needle aspiration cytology turned out to maligant in sputum test. The result of this research shows that, in diagnosis lung cancer, a test method of high sensitivity and specificity should be pursued. However, depending on the location and malignancy of the illness, diagnosis may not be obtained in some cases. Therefore, we conclude that the cytological tests performed for lung cancer testing such as sputum, bronchial brushing, bronchial washing, and fine needle aspiration cytology should be carried out in a mutually complementary manner.

• Journal of dental hygiene science
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• v.17 no.4
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• pp.358-367
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• 2017

The purpose of this study was to evaluate the influence of water infiltration and flexural strength changes in dental porcelain with glazing treatment. The block specimens were prepared as experimental materials, using feldspar type commercial dental porcelain; then, these were fired at $940^{\circ}C$ for 1 minute. The fired specimens were polished with a dimension of $40{\times}5.5{\times}5mm$. The specimens were distributed to two experimental groups: with and without glazing treatment specimens (n=5), and they were immersed in a solution of pH 7 for 3, 7, and 20 days at $40^{\circ}C$ after fabrication. To evaluate the flexural strength changes with water infiltration treatment in specimens with and without glazing, the 3-point flexural test was performed, using a universal testing machine until failure occurred. Starting powder and fired specimens consisted of amorphous and leucite crystalline phase. The Vickers hardness of fired specimens was more than 1.6 times higher than that of the enamel of natural teeth. According to porosimeter results, the specimens without glazing treatment exhibited a porosity of about 14.7%, whereas the glazed specimens exhibited the lowest porosity at about 1.1%. The average flexural strength of glazed specimens was higher than the flexural strength of specimens without glazing treatment (p<0.05). The flexural strength of all specimens with and without glazing treatment deteriorated with accelerated aging in the solution. In addition, significant differences between these two treatment groups were observed in all of the specimens treated at various water infiltration periods (p<0.05). The exposure of internal pores and micro-cracks in the surface due to polishing of the fired specimens influenced mechanical behaviors. Especially, the flexural strength in specimens without glazing treatment has shown significant degradation with the infiltration of water. Therefore, this study suggests that glazing processes can improve mechanical properties of dental porcelain.

• Journal of the Korean Wood Science and Technology
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• v.45 no.1
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• pp.107-115
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• 2017

In this study, the surface check reduction effect of preservative-treated Korean larch round-wood was investigated by applying three physical treatments, such as incising, kerfing, and kiln-drying. Moreover, the possibility of long-term service life was also checked by comparing the depth of surface check and the penetration depth of preservative. A rapid gradient of wood moisture content between surface and center causes a surface check. Thus, the effect of reducing surface check was carried out at the lowest equilibrium moisture content (EMC) condition, temperature ($2^{\circ}C$), humidity (44.6%), in outdoor locations in Korea until the test specimens reach to the 8.6% EMC. As a result, the preservative-treated specimens without incising, kerfing, kiln-drying (Type C) could not ensure the long-term service life due to a large surface check. Because the surface check depth of all specimens was deeper than the penetration depth of preservative. In case of the incising treated specimens (Type I), 80% of them, the depth of surface check was not deeper than the penetration depth of preservative. However, when a kerfing was additionally treated (Type B), a possibility of happening deeper surface check than penetration depth of preservative was increased rather than Type I.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.3
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• pp.280-293
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• 2004

Statement of problem. Glass fiber post is one of recent developments to accommodate esthetic restoration for endodontically treated teeth. This has many advantages over conventional post system in physical properties, esthetic factor, risk of root and restoration fracture, adhesion to core, radiopacity, removal and retrievabilty, biocompatibility and chemical stability. Purpose. This in vitro study was to evaluate the most suitable type of resin core for the glass fiber post through surveying the fracture modes and the maximum load that fractures the tooth. Material and methods. 50 sound maxillary premolars restored with glass fiber posts($ParaPost^{(R)}$ Fiber White) and different types of resin cores(ParaCore, $Z100^{TM}$, $Rebilda^{(R)}$ and $Admira^{(R)}$) were prepared and loaded to faiure in a universal test machine. The maximum fracture load and fracture mode were investigated in the specimens that were restored with resin and those of metal cast and core. With the data, Wilcoxon rank sum test was used to validate the significance between the test groups, and Tukey' s studentized range test was used to check if there is any significant statistical difference between each test group. Every analysis was approved with 95% reliance. Results. On measuring the maximum fracture load of teeth specimens, there was a significant difference between the maximum fracture loads of the tooth specimens. ParaCore showed the highest mean maximum fracture load followed by $Z100^{TM}$. And, the distribution of fracture mode of tooth specimens showed generally Type D, the three parted fracture of the core around the post was mostly seen(62.5%), and specifically, ParaCore showed 90% and $Z100^{TM}$ showed 100% Type D fracture. Conclusion. Referring to the values of maximum fracture load and mean compressive fracture load, ParaCore and $Z100^{TM}$ had high values and are recommended as tooth colored resin core material for glass fiber post. CLINICAL IMPLICATIONS. This study was carried out intending to be of aid in selecting the appropriate resin core for the glass fiber post. The dual cure type composite resin ParaCore and light cure type composite resin $Z100^{TM}$ have good properties and are recommended as tooth colored resin core material for glass fiber post.

• Journal of Technologic Dentistry
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• v.34 no.3
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• pp.227-235
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• 2012

Purpose: This study compared the surface hardness (Vickers) and microstructural characteristics between a type IV stone with and without die hardening treatment, a polyurethane die material. Methods: Materials used were a type IV stone(MG Crystal Rock), two die hardeners (Hardening bath, Epox-it), and a polyurethane resin material(Polyluck). Six specimens per group were prepared according to manufacturer's directions. The prepared specimens were tested by means of hardness test, one-way ANOVA analysis, scanning electron microscopic(SEM) observations and energy dispersive spectroscopic(EDS) analysis. Results: In the hardness test and its statistical analysis, there was no significant difference in the surface hardness between a type IV stone and type IV stone with die hardener coating, type IV stone mixed with an epoxy like material instead of water. In contrast, polyurethane resin material exhibited significantly greater surface hardness than other specimen groups (p<0.05). Conclusion: By considering the results of the hardness test, SEM observations and EDS analysis, although the die hardeners on type IV stone did not show remarkable improvement in surface hardness, the die hardener coating on the surface of type IV stone material did show decrease of microporous and improvement of surface defects.

• Economic and Environmental Geology
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• v.23 no.2
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• pp.127-133
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• 1990

Relation between fluid inclusions and mineralization has been studied for 30 granitoid specimens from 19 localities in South Korea. Polyphase inclusions are found in granitoid specimens of 9 localities. In the vicinities of 6 localities among them occurs any of W, Cu or Fe deposits of the vein-, stockwork-, skarn-or pegmatite-type. On the contrary, no ore deposit is reported near the granitoids characterized by no polyphase inclusion except only one locality. This fact implies that the occurrence of polyphase inclusions is a good indicator for such kinds of mineralization. Ores and country rocks of some of the deposits contain polyphase inclusions in their quartz crystals. The fact that many polyphase inclusions occur in granitoids and ore constituents suggests that highly saline hydrothermal solution played an important role for the formation of such kinds of deposits. On the contrary, the granite and the ore of the Mugug gold deposit have many fluid inclusions, but are free from the polyphase type.

• Electrical & Electronic Materials
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• v.7 no.6
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• pp.527-533
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• 1994

In this study, it was studied on dielectric breakdown strength and thennostability properties due to the structure variation of matrix resin and treatment of coupling agent of epoxy insulating materials. The interpenetrating network structure was formed by simultaneous heating curing the epoxy resin with single network structure and the methacrylic acid resin. Also inner structure was observed and the glass transition temperature was measured on these three type specimens. Dielectric breakdown properties were investigated by applying DC, AC and impulse voltage. As a result, the glass transition temperature and the dielectric breakdown strength of specimen with interpenetrating network structure was more higher than another two type specimens.

• Journal of Ocean Engineering and Technology
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• v.15 no.4
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• pp.60-65
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• 2001

Thermal spray coating is formed by a process in which melted particles flying with high speed towards substrate, then crash and spread on the substrate surface cooled and solidified in a very short time, Stacking of the particles makes coating. In this study, the exfoliation of $Al_2$O$_3$ and Ni-4.5wt.%Al thermally sprayed coating which were deposited by an atmospheric plasma spray apparatus are investigated using an AE method. A tensile test is conducted on notch specimens in a stress range below the elastic limit of substrate. The wave forms of AE generated from the three coating specimens can be classified by FFT analysis into two types which low frequency(type I waveform is considered to corresponds exfoliation of coating layers and type II waveform corresponds the plastic deformation of notch tip or the resultant fracture of coating. The fracture of the coating layers can estimate by AE event and amplitude, because AE features increase when the deformation generates.