• Earthquakes and Structures
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• v.8 no.5
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• pp.957-976
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• 2015

Recently, two energy-based response parameters, i.e., the absolute and the relative elastic input energy equivalent velocity, have been receiving a lot of research attention. Several studies, in fact, have demonstrated the potential of these intensity measures in the prediction of the seismic structural response. Although some ground motion prediction equations have been developed for these parameters, they only provide marginal distributions without information about the joint occurrence of the spectral values at different periods. In order to build new prediction models for the two equivalent velocities, a large set of ground motion records is used to calculate the correlation coefficients between the response spectral values corresponding to different periods and components of the ground motion. Then, functional forms adopted in models from the literature are calibrated to fit the obtained data. A new functional form is proposed to improve the predictions of the considered models from the literature. The components of the ground motion considered in this study are the two horizontal ones only. Potential uses of the proposed equations in addition to the prediction of the correlation coefficients of the equivalent velocity spectral values are shown, such as the prediction of derived intensity measures and the development of conditional mean spectra.

• Journal of the Korean earth science society
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• v.23 no.1
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• pp.15-29
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• 2002

Bayesian inversion for gravity and resistivity data was performed to investigate the cavity structure appearing as a lava tunnel in Cheju Island, Korea. Dipole-dipole DC resistivity data were proposed for a prior information of gravity data and we applied the geostatistical techniques such as kriging and simulation algorithms to provide a prior model information and covariance matrix in data domain. The inverted resistivity section gave the indicator variogram modeling for each threshold and it provided spatial uncertainty to give a prior PDF by sequential indicator simulations. We also presented a more objective way to make data covariance matrix that reflects the state of the achieved field data by geostatistical technique, cross-validation. Then Gaussian approximation was adopted for the inference of characteristics of the marginal distributions of model parameters and Broyden update for simple calculation of sensitivity matrix and SVD was applied. Generally cavity investigation by geophysical exploration is difficult and success is hard to be achieved. However, this exotic multiple interpretations showed remarkable improvement and stability for interpretation when compared to data-fit alone results, and suggested the possibility of diverse application for Bayesian inversion in geophysical inverse problem.

• The Journal of Korean Academy of Prosthodontics
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• v.39 no.1
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• pp.25-36
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• 2001

Among the numerous factors contributing to implant failure, the most common are infection, failure of proper healing and overload. These factors may occur combined. Implant fractures are one of the complications resulting from overload. Implant fracture is not a common feature, but once it occurs it causes very unpleasant circumstances for the patient as well as for the practitioner. Only few studies have been reported regarding this subject. Thus, little is known about its solutions. It is important that analyzing reasons for implant fracture and finding appropriate solutions. Factors leading to implant fracture are design, material defects, nonpassive fit of prosthetic framework and biomechanical overload. Previous studies have reported that implant fractures ares associated with marginal bone loss and occur mostly in the posterior regions and that most patients showing parafunctional habits also have implant fracture. Abutment and gold screw loosening or fracture were also observed in some of the cases previous to implant fracture. Similar observations were seen in our hospital as well. The following cases will present implant fracture cases which have been successfully treated regarding function and biomechanics. This was achieved by means of using increased number of futures, increasing fixture diameter and establishing proper occlusion.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.1
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• pp.1-11
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• 2008

Statement of problem: Over the past decade, increased demand for esthetically pleasing restorations has led to the development of all-ceramic systems. Recent reports suggest that the all-ceramic crowns have excellent physical properties, wear resistance, and color stability. In addition, numerous ceramics have excellent biocompatibility, a natural appearance, and improved physical bonding with resin composite luting agents. However, the brittle nature of ceramics has been a major factor in their restriction for universal usage. Functional occlusal loading can generate stress in the luting agent, and the stress distribution may be affected by the marginal geometry at the finish line. Tooth preparation for fixed prosthodontics requires a decision regarding the marginal configuration. The design dictates the shape and bulk of the all ceramic crowns and influences the fit at the margin. Purpose: The purpose of this study was to evaluate the stress distribution within marginal configurations of all- ceramic crowns (90-degree shoulder, 110-degree shoulder, 135-degree shoulder). Material and methods: The force is applied from a direction of 45 degrees to the vertical tooth axis. Three-dimensional finite element analysis was selected to determine stress levels and distributions. Results and conclusion: The result of stress level for the shoulder marginal configuration was more effective on stress distribution at 135-degree shoulder margin. But the stresses concentrated around at 135-degree shoulder margin. The stress decreased apically at the surface between cements and alumina core, and increased apically at the surface between alumina core and veneering porcelain.

• Journal of the Korean Data and Information Science Society
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• v.28 no.4
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• pp.797-810
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• 2017

The Korean peninsula is exposed to typhoons every year. Typhoons cause huge socioeconomic damage because tropical cyclones tend to occur with strong winds and heavy precipitation. In order to understand the complex dependence structure between strong winds and heavy precipitation, the copula links a set of univariate distributions to a multivariate distribution and has been actively studied in the field of hydrology. In this study, we carried out analysis using data of wind speed and precipitation collected from the weather stations in Busan and Jeju. Log-Normal, Gamma, and Weibull distributions were considered to explain marginal distributions of the copula. Kolmogorov-Smirnov, Cramer-von-Mises, and Anderson-Darling test statistics were employed for testing the goodness-of-fit of marginal distribution. Observed pseudo data were calculated through inverse transformation method for establishing the copula. Elliptical, archimedean, and extreme copula were considered to explain the dependence structure between strong winds and heavy precipitation. In selecting the best copula, we employed the Cramer-von-Mises test and cross-validation. In Busan, precipitation according to average wind speed followed t copula and precipitation just as maximum wind speed adopted Clayton copula. In Jeju, precipitation according to maximum wind speed complied Normal copula and average wind speed as stated in precipitation followed Frank copula and maximum wind speed according to precipitation observed Husler-Reiss copula.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.246-251
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• 2014

In case of prosthesis fabrication by CAD/CAM, location, area and contour of occlusal contacts can be adjusted so more functional occlusion can be acquired. Also, errors in a manufacturing process is reduced compared to cast metal prostheses and porcelain fused metal prostheses fabricated by conventional methods such as casting and porcelain build up. Therefore, prostheses by CAD/CAM show superior occlusion accuracy. Recently, virtual articulator function has been introduced to CAD/CAM system, which reproduces mandibular movement against maxilla. Thus, it is possible to consider occlusal interference in anterior/lateral movement as well as closing movement. There have been many studies on the marginal and internal fit of prostheses using zirconia but the occlusal fit of zirconia crown fabricated by CAD/CAM has not been researched as much. In this case report, 7 zirconia crowns were designed and fabricated by CAD/CAM for total 5 patients. The models of zirconia crowns before and after occlusal adjustment during intraoral try-in were scanned for occlusal contacts, which were compared to evaluate accuracy of prostheses and understand patterns of occlusal adjustment. Most of the occlusal adjustments were done on functional cusps and slopes of zirconia crown, and the magnitude of occlusal adjustment ranged from $15{\mu}m$ to $60{\mu}m$. In the zirconia crown fabricated with CAD/CAM systems, the occlusal adjustment is a necessary procedure, so additional procedures will be needed for compensating reduced mechanical properties.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.3
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• pp.224-233
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• 2024

The patient was a 69-year-old male who had decreased VDO and overbite of the anterior teeth due to severe teeth wear. Complete mouth rehabilitation was planned to restore esthetics and function. Due to the presence of a subgingival finish line, poor fit of the margin of the temporary crown, and insufficient oral hygiene management, gingival overgrowth and bleeding occurred in many teeth, and inaccurate impressions were taken. After dividing each arch and taking partial impressions, a transfer coping was made using pattern resin on each working model die, and after being placed on the abutment teeth, a master cast was made through pick-up impression taking to produce prosthesis. In this case, the final prosthesis produced on the second master cast were fitted in terms of proximal contact, marginal fit, vertical occlusal dimension, facial appearance, esthetics, and occlusion. After complete mouth rehabilitation, the patient was satisfied with function and esthetic appearance.

• The Journal of Advanced Prosthodontics
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• v.6 no.5
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• pp.372-378
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• 2014

PURPOSE. The porcelain fused to gold has been widely used as a restoration both with the natural esthetics of the porcelain and durability and marginal fit of metal casting. However, recently, due to the continuous rise in the price of gold, an interest towards materials to replace gold alloy is getting higher. This study compared the bond strength of porcelain to millingable palladium-silver (Pd-Ag) alloy, with that of 3 conventionally used metal-ceramic alloys. MATERIALS AND METHODS. Four types of metal-ceramic alloys, castable nonprecious nickel-chrome alloy, castable precious metal alloys containing 83% and 32% of gold, and millingable Pd-Ag alloy were used to make metal specimens (n=40). And porcelain was applied on the center area of metal specimen. Three-point bending test was performed with universal testing machine. The bond strength data were analyzed with a one-way ANOVA and post hoc Scheffe's tests (${\alpha}=.05$). RESULTS. The 3-point bending test showed the strongest ($40.42{\pm}5.72$ MPa) metal-ceramic bond in the nonprecious Ni-Cr alloy, followed by millingable Pd-Ag alloy ($37.71{\pm}2.46$ MPa), precious metal alloy containing 83% of gold ($35.89{\pm}1.93$ MPa), and precious metal alloy containing 32% of gold ($34.59{\pm}2.63$ MPa). Nonprecious Ni-Cr alloy and precious metal alloy containing 32% of gold showed significant difference (P<.05). CONCLUSION. The type of metal-ceramic alloys affects the bond strength of porcelain. Every metal-ceramic alloy used in this study showed clinically applicable bond strength with porcelain (25 MPa).

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.2
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• pp.169-175
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• 2020

Traditionally, gingival retraction has been performed to obtain customized abutment impressions with subgingival margins of the implant supported prosthesis. However, gingival retraction may have side effects such as gingival recession and bleed, leading to an inaccurate impression. In order to prevent these problems, in this case, the new technique has been introduced; a customized abutment which is designed for superimposition is used. Before the connection of the abutment to the implant fixture, pre-scanned shape data are stored, and then the optical impression without gingival retraction is obtained after connecting to the fixture. The suprastructure is fabricated by superimposing the two data. This technique showed the clinical efficacy of fabricating the implant supported prosthesis with subgingival margin, which satisfied the aesthetics, convenience, and clinically acceptable marginal and internal fit.

• International Journal of Highway Engineering
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• v.10 no.4
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• pp.199-211
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• 2008

This study deals with the side right-angle collisions of 4-legged signalized intersections in Cheongju. The goals are to analyze the characteristics of accidents and to find out the accident factors that affect severity using ordered probit model. In pursuing the above, the study uses the data of 580 side right-angle collisions occurred at the 181 intersections(2004-2005). The analyses show that more accidents were occurred in the nighttime and in going straight. The main cause was analyzed to be the red-light violation. Also, the main results of modeling are the following, First, the likelihood ratio index is 0.094 and t-ratio values that explain goodness of fit are significant. Second, minor road traffic volumes, minor road lanes, major road left-turn lanes, major road left-turn signal, major road yellow signal time, cross angle, major and minor road speed limits are significant factors affecting crash severities at signalized intersections.