• The Journal of the Korean dental association
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• v.56 no.12
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• pp.686-694
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• 2018

Purpose: The aim of this study was to evaluate the validity of swept-source optical coherence tomography (SS-OCT) for detecting sealant microleakage. Materials and Methods: A total of 31 extracted sound human molar, assigned as suitable for sealant application, were chosen and divided into two groups: (1) no microleakage group and (2) microleakage group by applying sealant using the different methods. All specimens were immersed in 1% methylene blue for 24 h and sectioned to confirm the absence or presence of sealant microleakage as a gold standard method. Subsequently, all the sectioned specimens were digitally photographed using a microscope with a magnification of ${\times}50$. Presence of microleakage was evaluated on a 2-point rating scale. The association of histological method with conventional methods (visual and tactile assessment) and SS-OCT was assessed using a chi-squared test. The intra- and inter-examiner reliability was calculated using Cohen's Kappa. Results: The SS-OCT showed a sensitivity of 0.73 and a specificity of 1.00, while visual and tactile assessment showed a sensitivity of 0.67 and a specificity of 0.86. The inter-examiner reliability of SS-OCT was 0.79, whereas that of the visual and tactile assessment was 0.53. Conclusions: SS-OCT can be used to non-invasively detect sealant microleakage and to monitor pit and fissure sealant in the clinics.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.669-676
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• 2018

The "pseudo-wedge" failure is a name for a complex instability occurring at the Sarcheshmeh open-pit mine (Iran). The pseudo-wedge failure contains both the rock bridge failure and sliding along pre-existing discontinuities. In this paper, a cross section of the failure area was first modeled using a bonded-particle method. The results indicated development of tensile cracks at the slope toe which explains the freedom of pseudo-wedge blocks to slide. Then, a three-dimensional discrete element method was used to perform a block analysis of the instability. The technique of shear strength reduction was used to calculate the factor of safety. Finally, the influence of geometrical characteristics of the mine wall on the pseudo-wedge failure was investigated. The safety factor significantly increases as the dip and dip direction of the wall decrease, and reaches an acceptable value with a 10-degree decrease of them.

• Journal of the Korean Society of Food Culture
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• v.17 no.5
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• pp.638-645
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• 2002

The purpose of this study is to evaluate the quality characteristics and consumer acceptance of the Kimchi affected by the storage method and the duration. The characteristics of Kimchi fermented and stored in the traditional method, such as cave facility or pit storage on the shore were compared to the Kimchi which was stored in the Kimchi refrigerator using the physicochemical and sensory evaluation. The quality of Kimchi stored by the Kimchi refrigerator was most acceptable with 3 month storage, while that of Kimchi stored by the storage facility under the ground on the shore was 1 month storage. Shelf life of Kimchi was extended up to 5 month stored by Kimchi refrigerator, and 3 month for the Kimchi stored under the ground on the shore.

• Transactions of the Society of Information Storage Systems
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• v.1 no.2
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• pp.132-136
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• 2005

It is widely accepted that the reading mechanism of Super-RENS(super-resolution near field structure) and Super-ROM(super-resolution read only memory) is closely related with non-linear temperature dependent material properties such as refractive indices, phase change. Furthermore, the dynamic change of the temperature distribution also an essential part of reading mechanism of Super-RENS/ROM. Therefore, the knowledge of the temperature distribution as a function a time is one of the important keys to reveal the physics of reading mechanism in Super-RENS/ROM. We calculated time-dependent temperature distribution in a 3-dimensional Super-ROM disk structure when moving laser beam is irradiated. With a help of commercial software FEMLAB which employed finite element method, we simulated the temperature distribution of ROM structure whose pit diameter is 120-nm with 50-nm depth. Energy absorption by moving laser irradiation, time variations of heat transfer processes, heat fluxes, heat transfer ratios, and temperature distributions of the complicate 3-dimensional ROM structure have been obtained.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.20 no.5
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• pp.202-206
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• 2010

Single crystals of $ZnWO_4$ were grown successfully in the [100], [010] and [001] directions using the Czochralski method. The growth parameters and the formation of slip plane in $ZnWO_4$ crystals were studied. $ZnWO_4$ crystals had a cleavage plane of (010). The dislocation density on the (010) plane at the center of the crystal was lower than that of the edge region. It was inferred that the high density at the edge of the crystals was caused by the thermal gradient during crystal growth. The etch pit arrangement revealed the (100) slip plane to be most active during crystal growth.

• Journal of applied mathematics & informatics
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• v.30 no.3_4
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• pp.395-411
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• 2012

Several methods with order higher than that of Newton methods which are of order 2 have been reported in literature for solving nonlinear equations. The focus of most of these methods was to economize on/minimize the number of function evaluations per iterations. We have demonstrated here that there are several computational pit-falls, such as the violation of fixed-point theorem, that one could encounter while using these methods. Further it was also shown that the overall computational complexity could be more in these high-order methods than that in the second-order Newton method.

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.112-122
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• 1995

In this work, prediction of fatigue life and fatigue crack growth are studied. 4th order polynominal function is presented to describe the crack growth behaviors from artifical pit of SM45C steel. Crack growth curves obtained from 4th order polyminal growth equations are in good agreement with experimental data The crack growth behaviors at arbitrary stress levels and investigated by the concept of elastic-plastic fracture mechanics using ${\Delta}J$. Fatigue life prediction are carried out by numerical integral method. Prediction lives obtained by proposed method in this study, is in good agreement with the experimental ones. Life prediction results calculated by using of ${\Delta}J$ better than those of ${\Delta}K$.

• Progress in Superconductivity
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• v.5 no.1
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• pp.65-69
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• 2003

Many researches on fabrication process for BSCCO precursor powders have been developed for high J$_{c}$ BSCCO-2223 tape. Spray pyrolysis method for fabrication of precursor powder has many advantages, such as high purity, fine particle size and low carbon content of BSCCO precursor powder. Fine, spherical powders were prepared by ultrasonic spray pyrolysis from the aqueous solution of metal nitrates. BSCCO precursor powders were synthesized with various solutes concentration and heat treatment conditions. Average particle size for spray pyrolysis powders was $1.5∼3\mu\textrm{m}$. Bi-2223/Ag tape was prepared by PIT method and followed by various sintering conditions. BSCCO precursor powders were characterized by XRD, SEM, EDS, Carbon content and particle size analysis.s.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.289-292
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• 2002

In this study, a topography based hydrologic model (TOPMODEL) was tested on the Anseong-cheon watershed. Pit in watershed was removed by liner trend surface interpolator. The DTM Analysis program is used to derived a distribution of ln($a/tan{\beta}$) values from DEM (Digital Elevation Model) using the MDF (Multiple Direction Flow) algorithm of Quinn et al (1995). Current TOPMODEL program limits are number of time step, ln($a/tan{\beta}$) increment, delay histogram ordinate and size of subcatchment pixel maps. Therefore, TOPMODEL is not suitable for application of large watershed. Muskingum method and watershed division enhance grid pixel resolution for rainfall-runoff simulation accuracy.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.3
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• pp.80-88
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• 2010

A simple computational model for modeling of subsurface crack growth under cyclic contact loading is presented. In this model, it is assumed that the initial fatigue crack will initiate in the region of the maximum equivalent stress at certain depth under the contacting surface. The position and magnitude of the maximum equivalent stress are determined by using the equivalent contact model, which is based on the Hertzian contact conditions with frictional forces. The virtual crack extension method is used for simulation of the fatigue crack growth from the initial crack up to the formation of the surface pit due to contact fatigue. The relationships between the stress intensity factor and crack length are then determined for various combinations of equivalent contact radii and loadings.