• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.2
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• pp.107-112
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• 2001

The prosthodontic treatment of severely resorbed edentulous patients has been one of the frustrating areas due to extensive loss of tissues. The integrated neuromuscular balance among tongue, lip, and cheek is compromised. The retention, stability, and support are the three major factors to influence the clinical outcome. Fish described a denture as having three surface, with each surface playing an independent and important role in the over all fit, stability, and comfort of the denture. He recommended that the polished surface should be a series of inclines so that pressure from muscular activity will retain dentures. Within the denture space there is an area that has been termed the neutral zone. The neutral zone is that area in the mouth where, during function, the forces of the tongue pressing outward are neutralized by the forces of the cheeks and lips pressing inward. According to Jacobson and Krol, neuromuscular control interacts to provide retention and the relationship of polished surface of denture base to the surrounding muscular structure of orofacial capsule facilitates the stability and retention. This neutral zone concept has been demonstrated with various modification by a number of authors. The theory used to develop the denture base contours is based on the belief that the muscle should functionally mold not only the border but the entire polished surface. Lott and Walsh reported the clinical success on complete mandibular dentures with application of neutral zone concept. A number of studies demonstrated that denture stability and retention are more dependent on correct position of the teeth and correct contour of external surfaces of the denture in a severely resorbed alveolar ridge. This article presents a prosthodontic approach to treatment of a edentulous patient using neutral zone technique to improve the retention and stability of the prosthesis.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.28 no.5
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• pp.454-469
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• 2006

Today, there is considerable evidence to support a cause-effect relationship between microbial colonization and the pathogenesis of implant failures. The presence of bacteria on implant surfaces may result in an inflammation of the peri-implant mucosa, and, if left untreated, it may lead to a progressive destruction of alveolar bone supporting the implant, which has been named as peri-impantitis. Several maintenance regimens and treatment strategies for failing implants have been suggested. Recently, in addition to these conventional tools, the use of different laser systems has also been proposed for treatment of peri-implant infections. As lasers can perform excellent tissue ablation with high bactericidal and detoxification effects, they are expected to be one of the most promising new technical modalities for treatment of failing implants. It is introduced that Er,Cr:YSGG laser, operating at 2780nm, ablates tissue by a hydrokinetic process that prevents temperature rise. We studied the change of the titanium implant surface under scanning electron microscopy after using Er,Cr:YSGG laser at various energies, irradiation time. In this study, Er,Cr:YSGG laser irradiation of implant fixture showed different effects according to implant surface. Er,Cr:YSGG laser in TPS surface with RBM not alter the implant surface under power setting of 4 Watt(W) and irradiation time of 30sec. But in TPS surface with $Ca_3P$ coating alter above power setting of 2W and irradiation time of 10sec. TPS surface with RBM showed microfracture in 4W, 30sec and TPS surface with $Ca_3P$ coating showed destruction of fine crystalline structure, melting in excess of 2W, 10sec. We concluded that proper power setting, air, water of each implant surface must be investigated and implant surface must be irradiated under the damaged extent.

• International Journal of Highway Engineering
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• v.4 no.2 s.12
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• pp.33-42
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• 2002

The cracks in the pavements result from drying shrinkage, temperature change, repeated traffic loadings and so on. The reduction of soil support, spatting and many local failures are caused by water and incompressible foreign materials infiltrated into the cracks. In order to reduce this kind of problems the crack width must be controlled and managed by the accurate measurement. The current method is a visual survey using a microscope, which requires traffic blocking. The purpose of this study is to find the best condition to measure accurate crack width using automated pavement condition survey equipment running at the similar speed as other vehicles. In this study pavement surfaces are filmed on an enlarged scale by the camera with a zoom lens, and then the proper focal distance is determined according to the crack width through a pilot survey. The conditions for measurement of the accurate crack width using the image processing technique are suggested by comparing crack widths surveyed using a microscope in the field with those computed by various factors in the image processing program, STADI-2. In conclusion, the camera with a focal distance of 75m could detect crack range of 0.5mm$\sim$1.2mm In width with an accuracy of 80% for CRCP. The camera with a focal distance of 12.5mm could detect crack range of 1.8mm$\sim$3.3mm in width with an accuracy of 90% for asphalt pavement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.160-166
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• 2018

The worldwide semi-conductor market has been growing for a long time. Manufacturing lines of semi-conductors need to handle several types of toxic gases. In particular, they need to be controlled accurately in real time. This type of toxic gas control system consists of many different kinds of parts, e.g., fittings, valves, tubes, filters, and regulators. These parts obviously need to be manufactured precisely and be corrosion resistant because they have to control high pressure gases for long periods without any leakage. For this, surface machining and hardening technologies of the metal block and metal gasket need to be studied. This type of study depends on various factors, such as geometric shapes, part materials, surface hardening method, and gas pressures. This paper presents strong concerns on a series of simulation processes regarding the differences between the inlet and outlet pressures considering several different fluid velocity, tube diameters, and V-angles. Indeed, this study will very helpful to determine the important design factors as well as precisely manufacture these parts. The EP (Electrolytic Polishing) process was used to obtain cleaner surfaces, and hardness tests were carried out after the EP process.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.1
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• pp.49-61
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• 2021

The repeated shipboard measurements that have been conducted by the National Institute of Fisheries Science (NIFS) for more than a half century, provide the valuable long-term hydrographic data with high spatial-temporal resolution. However, this unprecedent dataset has been rarely used for oceanic climate sciences because of its reliability issue. In this study, temporal variability of salinity error in the NIFS data was quantified by means of extremely small variability of salinity in the deep layer of the south-western East Sea, in order to contribute to studies on long-term variability of the East Sea. The NIFS salinity errors estimated on the isothermal surfaces of 1℃ have a remarkable temporal variation, such as ~0.160 g/kg in the year of 1961~1980, ~0.060 g/kg in 1981~1994,~0.020 g/kg in 1995~2002, and ~0.010 g/kg in 2003~2014 on average, which basically represent bias error. In the recent years, even though the quality of salinity has been improved, there still remain relatively large bias errors in salinity data presumably due to failure of salinity sensor managements, especially in 2011, 2013, and 2014. On the contrary, the salinity in the year of 2012 was very accurate and stable, whose error was estimated as about 0.001 g/kg comparable to the salinity sensor accuracy. Thus, as long as developing proper data quality control procedures and sensor management systems, I expect that the NIFS shipboard hydrographic data could have good enough quality to support various studies on ocean response to climate variabilities. Additionally, a few points to improve the current NIFS shipboard measurements were suggested in the discussion section.

• Korean Journal of Heritage: History & Science
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• v.55 no.2
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• pp.186-197
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• 2022

The Daejanggakgibi Stele of Silleuksa Temple in Yeoju is a stone stele from the Goryeo Dynasty that is inscribed with various stories about the construction of Daejanggak, a place where Buddhist scriptures were kept. This stele has been maintained for a long time in a state in which discoloration of the body has occurred, and the inscription has been partially damaged due to dozens of cracks. Using non-destructive analysis methods for stone artifacts, material investigation, portable X-ray fluorescence analysis, and ultrasonic velocity analysis for the stele were performed. It was confirmed that the stele body was composed of light gray crystalline limestone, and the base stone, support stone, and cover stone were medium-grained biotite granite. Portable X-ray fluorescence analysis confirmed that iron(Fe) was an original coloring element of the stele surface. From the distribution pattern of the coloration, it can be inferred that iron-containing materials flew down from between the stele body and the cover stone. Thereafter, living organisms or organic contaminants attached to it so that yellow and black contaminants were formed. Ultrasonic diagnosis revealed that the physical property of both the front and back surfaces ranged from fresh rocks(FR) to completely weathered rocks(CW), and the average weathering index was grade 3(intermediate). However, the point where cracks developed intensively was judged to be the completely weathered stage(CW), and some cracks located in the upper and lower parts of the stele bear potentially very high risk. It is necessary to monitor the movement of these cracks and establish reinforcement measures for conservation in the future.

• The Journal of Korean Academy of Prosthodontics
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• v.48 no.3
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• pp.194-201
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• 2010

Purpose: The purpose was to compare the marginal fidelity and the fracture resistance of the zirconia crowns according to the various coping designs with different thicknesses and cement types. Materials and methods: Zirconia copings were designed and fabricated with various thicknesses using the CAD/CAM system (Everest, KaVo Dental GmbH, Biberach., Germany). Eighty zirconia copings were divided into 4 groups (Group I: even 0.3 mm thickness, Group II: 0.3 mm thickness on the buccal surface and the buccal half of occlusal surface and the 0.6 mm thickness on the lingual surface and the lingual half of occlusal surface, Group III: even 0.6 mm thickness, Group IV: 0.6 mm thickness on the buccal surface and the buccal half of occlusal surface and the 1.0 mm thickness on the lingual surface and the lingual half of occlusal surface) of 20. By using a putty index, zirconia crowns with the same size and contour were fabricated. Each group was divided into two subgroups by type of cement: Cavitec$^{(R)}$ (Kerr Co, USA) and Panavia-$F^{(R)}$ (Kuraray Medical Inc, Japan). After the cementation of the crowns with a static load compressor, the marginal fidelity of the zirconia crowns were measured at margins on the buccal, lingual, mesial and distal surfaces, using a microscope of microhardness tester (Matsuzawa, MXT-70, Japan, ${\times}100$). The fracture resistance of each crown was measured using a universal testing machine (Z020, Zwick, Germany) at a crosshead speed of 1 mm/min. The results were analyzed statistically by the two-way ANOVA and oneway ANOVA and Duncan's multiple range test at $\alpha$=.05. Results: Group I and III showed the smallest marginal fidelity, while group II demonstrated the largest value in Cavitec$^{(R)}$ subgroup (P<.05). For fracture resistance, group III and IV were significantly higher than group I and II in Cavitec$^{(R)}$ subgroup (P<.05). The fracture resistances of Panavia-$F^{(R)}$ subgroup were not significantly different among the groups (P>.05). Panavia-$F^{(R)}$ subgroup showed significantly higher fracture resistance than Cavitec$^{(R)}$ subgroup in group I and II (P<.05). Conclusion: Within the limitation of this study, considering fracture resistance or marginal fidelity and esthetics, a functional ceramic substructure design of the coping with slim visible surface can be used for esthetic purposes, or a thick invisible surface to support the veneering ceramic can be used depending on the priority.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.349-356
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• 2006

We have investigated adsorption and desorption properties of CO adsorption on silica supported Ru/Ni alloys at various Ru/Ni mole content ratio as well as CO partial pressures using Fourier transform infrared spectrometer (FT-IR). For Ru-$SiO_{2}$ sample, four bands were observed at $2080.0cm^{-1}$, $2021.0{\sim}2030.7cm^{-1}$, $1778.9{\sim}1799.3cm^{-1}$, $1623.8cm^{-1}$ on adsorption and three bands were observed at $2138.7cm^{-1}$, $2069.3cm^{-1}$, $1988.3{\sim}2030.7cm^{-1}$ on vacumn desorption. For Ni-$SiO_{2}$ sample, four bands were observed at $2057.7cm^{-1}$, $2019.1{\sim}2040.3cm^{-1}$, $1862.9{\sim}1868.7cm^{-1}$, $1625.7cm^{-1}$ on adsorption and two bands were observed at $2009.5{\sim}2040.3cm^{-1}$, $1828.4{\sim}1868.7cm^{-1}$ on vacumn desorption. These absorption bands correspond with those of the previous reports approximately. For Ru/Ni(9/1, 8/2, 7/3, 6/4, 5/5; mole content ratio)-$SiO_{2}$ samples, three bands were observed at $2001.8{\sim}2057.7cm^{-1}$, $1812.8{\sim}1926.5cm^{-1}$, $1623.8{\sim}1625.7cm^{-1}$ on adsorption and three bands were observed at $2140.6cm^{-1}$, $2073.1cm^{-1}$, $1969.0{\sim}2057.7cm^{-1}$ on vacumn desorption. The spectrum pattern observed for Ru/Ni-$SiO_{2}$ sample at 9/1 Ru/Ni mole content ratio on CO adsorption and on vacumn desorption is almost like the spectrum pattern observed for Ru-$SiO_{2}$ sample. But the spectrum patterns observed for Ru/Ni-$SiO_{2}$ samples under 8/2 Ru/Ni mole content ratio on CO adsorption and vacumn desorption are almost like the pattern observed for $Ni-SiO_{2}$ sample. It may be suggested surfaces of alloy clusters on the Ru/Ni-$SiO_{2}$ samples contain more Ni components than the mole content ratio of the sample considering the above phenomena. With Ru/Ni-$SiO_{2}$ samples the absorption band shifts may be ascribed to variations of surface concentration, strain variation due to atomic size difference, variation of bonding energy and electronic densities, and changes of surface geometries according to surface concentration variation. Studies for CO adsorption on Ru/Ni alloy cluster surface by LEED and Auger spectroscopy, interation between Ru/Ni alloy cluster and $SiO_{2}$, and MO calculation for the system would be needed to look into the phenomena.