• Applied Microscopy
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• v.50
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• pp.8.1-8.7
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• 2020

Two thickness measurement methods using an electron energy loss spectroscopy (EELS) and 10a convergent beam electron diffraction (CBED) were compared in an Fe-18Mn-0.7C alloy. The thin foil specimen was firstly tilted to satisfy 10a two-beam condition. Low loss spectra of EELS and CBED patterns were acquired in scanning transmission electron microscopy (STEM) and TEM-CBED modes under the two-beam condition. The log-ratio method was used for measuring the thin foil thickness. Kossel-Möllenstedt (K-M) fringe of the $13{\ba{1}}$ diffracted disk of austenite was analyzed to evaluate the thickness. The results prove the good coherency between both methods in the thickness range of 72 ~ 113 nm with a difference of less than 5%.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.303-315
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• 1995

An adequate and homogeneous cure of light-activated restroative material is very important for improvement of marginal adaptation and prevention of marginal leakage, secondary caries and pulpal irritation as well as expressing natural physical property of that material. The purpose of this study was to evaluate the change of surface hardness and cure uniformity of light-activated glass ionomer cements. Restorative(Fuji II LC, Vitremer) and lining(Baseline VLC, Vitrebond) light-activated glass ionomer cements were investigated for this study. The surface hardness of the top and bottom surfaces and cure uniformity of each 1mm, 1.5mm, 2mm, 2.5mm & 3mm in the thickness of specimen were measured immediately, at 1 hour, 24 hours and 1 week after light activation. The surface hardness change and cure uniformity of all the specimens were measured by Knoop hardness tester. The results were as follows. 1. The surface hardness of top and bottom surfaces in all groups increased with time(p<0.01). 2. Both top and bottom surfaces hardness of Vitrebond group measured immediately after light-activation were significantly lower than those of the other groups(p<0.01). 3. The surface hardness of top and bottom surfaces of restorative light -activated glass ionomer cements was higher than those of lining materials at 1 week(p<0.10). 4. Surface hardness of Vitremer group decreased as the specimen thickness increased, except top and bottom surfaces hardness of the specimen at 1 week(p<0.01). There was no significant difference in the surface hardness of Fuji II LC with changes in the thickness except bottom surface hardness of specimen at 24 hours and 1 week (p>0.05). 5. Surface hardness of Vitrebond group significantly decreased as the specimen thickness increased(p<0.01). There was no significant difference in the surface hardness of Baseline VLC group with changes in the thickness except bottom surface hardness of specimen measured immediately after light -activation(p>0.05). 6. The hardness ratio of top against bottom surface in all groups decreased with time(p<0.05). 7. There was no significant difference in the hardness ratio of top against bottom surface with changes of the thickness except Vitrebond group, 24 hours and 1 week of Vitremer group and 1 week of Baseline VLC group (p>0.05). These results suggest that surface hardness of restorative ligh-activated glass ionomer cements were highter than those of lining light-activated materials. In all groups, the surface hardness and cure uniformity continuously increased with time.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.13-18
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• 2004

The objective of this study is to investigate fracture toughness and fatigue crack propagation behavior in the Reduced Activation Ferritic Steel (RAFs) JLF-I. The fracture toughness tests were performed with various size(plane size and thickness) and various side groove of specimens. The fatigue crack propagation behavior of the JLF-I steel was investigated by the constant-amplitude loading test for the stress ratios R=O.I, 0.3 and 0.5 respectively. The effects of stress ratios and specimen size on the fatigue crack growth behaviors for JLF-I steel were discussed within the Paris law. The test results showed the standard CT specimen with the side groove of 40 % represented a valid fracture toughness. The fracture resistance curve increased with increasing plane size and decreased with increasing thickness. However, the fracture resistance curve of half size specimen was similar to that of the standard specimen. The fatigue crack propagation rate of a half size specimen was similar to that of a full size specimen at the stress ratios of 0.1, 0.3 and 0.5 respectively. The fatigue crack propagation behavior of this material were evaluated by using a half size specimen.

• Journal of Technologic Dentistry
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• v.38 no.3
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• pp.127-133
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• 2016

Purpose: Currently advanced in Dental CAD/CAM technology increase a use of Co-Cr sinter metal block at Dental CAD/CAM part traditionally it has been being used with metal casting method. There is an advantage that can leave out a step of investment and casting as well as reducing a working time to compare with conventional casting method in a dry milling. Methods: In this research, compare a deformation of before and after sinter result of Co-Cr sinter metal block. Design a specimen figure by 3D CAD software and transformed it to a STL file can be used at Dental CAD/CAM. With a transformed STL file, milled a Co-Cr sinter metal specimen by using a Dental CAD/CAM dry milling machine. It arrived at the following conclusions after measuring an outer form and thickness of a machined specimen and then after sinter measure it again in a way of before sinter measurement method. Results: It is confirmed that there is no error while a 3D design figure specimen is transformed to a Dental CAD data. It is observed that there is no error at Co-Cr sinter metal specimen which consider a length of single coping and bridge. Conclusion: It is observed that there is no deformation at a specimen of AS05 and AB05 are made of 0,5mm thickness. On the other hand, the out of range of deformation is observed at a specimen of AS10 and AB10 which are made of 1mm thickness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05b
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• pp.46-49
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• 2001

To estimate the influence of electrical properties due to the poly back seal(PBS). we were investigated defect density in surface by deposition thickness and breakdown voltage in specimens. Deposition thickness of specimen is prepared from 7,000[$\AA$] to 13,000[$\AA$], respectively. From the results, it is confirmed that PBS deposition thickness of 10,000[$\AA$] among the specimen is decreased defect density by contribution of the gettering effect.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.447-452
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• 1987

In this paper, the dependence of piezoelectric properties in the 0-3 composite system of piezoelectric-ceramics polymer materials on particle size of ceramics were investigated. Radial mode and thickness mode of composite were observed similar to single phase of piezoelectric ceramics. The measured values of dielectric constant and dissipation factor were dependent on particle size, which increased with the increasing particle size. the planar coupling factor, thickness coupling factor and thickness frequency constant with the particle size were almost constant, while planar frequency constant increased. The thickness coupling factor decreased with the increasing thickness of specimen. It is found that maximum voltage coeffidient was calculated on the specimen with particle size smallar than 46 ${\mu}m$.

• Structural Engineering and Mechanics
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• v.42 no.5
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• pp.701-713
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• 2012

Results pertaining to 3D investigations on the effect of the thickness on the stress fields at the crack front are presented. A 3D finite element analysis is performed using a modified single edge-notched tension specimen configuration, with an inclined crack to include mixed mode I-II. A technique to mesh the crack front (3D) with singular finite elements in ANSYS without using third party software is introduced and used in this study. The effect of the specimen thickness is explicitly investigated for six thicknesses ranging from 1 to 32 mm. In addition, three crack inclination angles, including pure Mode-I, are used to study the effect of mixed-mode I-II fracture. An attempt is made to correlate the extent of a particular stress state along the crack front to thickness. In addition, ${\sigma}_{zz}/{\nu}({\sigma}_{xx}+{\sigma}_{yy})$ contours at the crack front are presented as a useful means to analyze the stress state.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.3396-3402
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• 2014

The importance of shape design for strength is highly regarded when applied to thin plate products in Ceramic Injection Molding (CIM), such as cases for electronic goods. This study analyzed the characteristics of the mechanical strength of CIM product by measuring the flexural strength and elastic modulus through a 3-point bending test according to the thickness of a thin plate test piece prepared by CIM. The specimen with a thickness of 0.48mm required a 82.9~94.5N fracture load, whereas a 1.0mm thick test piece required 233.6~345.8N. The increase in thickness by 0.5mm resulted in a 3-fold increase in the fracture load, whereas the elastic modulus decreased by 20%. The thicker the specimen, the lower relative density and surface hardness of the specimen. This is because the thicker the specimen, the lower the powder fraction of the ceramic mixture, and the material properties partially change after sintering.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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• pp.788-795
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• 2008

To understand the tensile behaviors of GFRP at low temperature, three types of specimen have been used in this study. Tensile properties and fracture mechanisms for three orthogonal orientations of plain weave glass fabric reinforced epoxy resin laminate were investigated at temperature range of about -30 to $15^{\circ}C$. The tensile properties of axial and edge type specimen decrease slightly with decreasing temperature to $-20^{\circ}C$. However, at $-30^{\circ}C$ the decreases in the tensile properties increased considerably. Below $-20^{\circ}C$, thickness type specimen showed a marked decreases in the tensile properties. It was obvious that the fracture manner of thickness type specimen was adhesive failure at above $-10^{\circ}C$ and a mixed adhesive and cohesive failure at below $-20^{\circ}C$.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.4
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• pp.395-400
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• 2009

As the variables affecting the fatigue behavior have uncertainty, the fatigue crack propagation is stochastic in nature. Therefore, the fatigue life prediction is critical for the design and the maintenance of many structural components. In this study, fatigue experiments are conducted on the specimens of magnesium alloy under the different thicknesses of specimen. The effects of specimen thickness on the probability distribution of the fatigue crack propagation life and the crack size are estimated experimentally. The probability distribution of the crack size and the fatigue life for different specimen thicknesses are investigated by Anderson-Darling test and the best fit for those probability distributions are also presented.