• Korean Journal of Materials Research
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• v.9 no.5
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• pp.533-537
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• 1999

ATO(Sb doped $SnO_2$) thin films whose thicknesses were 600, 1100 and $2100\AA$ were prepared by DC magnetron sputtering method. They showed the lowest resistivity at DC sputtering power 0.24kW and had lower resistivity with increasing thickness. The power dependence of resistivity among ATO thin films was also different with thickness. The increase of carrier concentration in ATO thin films was responsible for the decrease of resistivity with thickness increase. ATO thin films which were prepared at 30sccm oxygen flow rate showed a great change of sheet resistance under 1M HCl solution. The investigation of SAM(Scanning Auger Microprobe) revealed that oxygen atomic percentage on the surface of ATO thin films was changed. The decrease of sheet resistance also occurred when ATO thin films, prepared at 30sccm oxygen flow rate, were exposed to air for a long period of time. For this reason, it was considered that the desorption of oxygen on ATO surface was accelerated by HCl.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.4
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• pp.242-253
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• 2011

Skin frictional drag reduction efficiency of "stiff" compliant coating was investigated in a wind tunnel experiment. Flat plate compliant coating inserts were installed in a wind tunnel and the measurements of skin frictional drag and velocity field were carried out. The compliant coatings with varying viscoelastic properties had been prepared using different composition. In order to optimize the coating thickness, the most important design parameter, the dynamic viscoelastic properties had been determined experimentally. The aging of the materials (variation of their properties) during half a year was documented as well. A design procedure proposed by Kulik et al. (2008) was applied to get an optimal value for the coating thickness. Along with the drag measurement using the strain balance, velocity and pressure were measured for different coatings. The compliant coatings with the thickness h = 7mm achieved 4~5% drag reduction within a velocity range 30~40 m/s. The drag reduction mechanism of the attenuation of turbulence velocity fluctuations due to the compliant coating was demonstrated. It is envisioned that larger drag reduction effect is obtainable at higher flow velocities for high speed trains and subsonic aircrafts.

• Composites Research
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• v.34 no.1
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• pp.30-34
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• 2021

This paper present a three-dimensional unit cell finite element analysis to predict the pull-out behavior of a single stitch in a composite laminate. The stitching process used for this study correspond to the I-fiber stitching method that has been studied by the Composite Structures Lab (CSL) as a new through-thickness reinforced method. A total of six cases were analyzed, which were divided in two groups by the stitching yarn used, 6k and 12k. Each group of cases have three different thickness according to the amount of plies; 16 plies, 32 plies and 64 plies. The finite element analysis used the cohesive zone method to characterize the single stitch reinforcement in the interface. Due to the complexity of the load vs displacement curves taken from the experimental results, a bilinear and trilinear bridging laws were implemented in the models. The cohesive parameters used for each case showed a good agreement with the experimental data and can be used for future studies.

• Transactions of Materials Processing
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• v.13 no.1
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• pp.65-71
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• 2004

Recent electronic equipment becomes smaller, more functional, and more complex. According to these trends, LTCC(low temperature co-fired ceramic) has been emerged as a promising technology in packaging industry. It consists of multi-layer ceramic sheet, and the circuit has 3D structure. In this technology via hole formation plays an important role because it provides an electric path for the packaging interconnection network. Therefore via hole qualify is very important for ensuring performance of LTCC product. Via holes are formed on the green sheet that consists of ceramic(before sintering) layer and PET(polyethylene terephthalate) one. In this paper we found the correlation between hole quality and process condition such as PET thickness and ceramic thickness. The shear behavior of double layer sheet by micro hole punching which is different from that of single layer one was also discussed.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.1
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• pp.111-120
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• 2014

Purpose: This study was to investigate changes in the thickness of cornea, curvature of cornea, and aberration depending on the water contents, materials, and refractive power of contact lens. Methods: The differences in the corneal thickness between pre- and post-wearing the lenses were compared using 5 kinds of lenses. The changes in the corneal thickness, the curvatures of the anterior and posterior cornea, and high order aberration (HOA) before and after wearing the lenses were investigated at the center of the cornea, and the different distance and the direction away from the center of the cornea. For the equipments of measurement, ORB ScanII (Bausch & Lomb Inc, ver 3.14) was used to measure the corneal topography and thickness, and Zywave (Bausch & Lomb Inc, ver 5.20) was used to analyze the high order aberration. Results: Five (S1, S2, S3, T1, T2) of the lens was used for this study, excluding the lens T2 lens has four lenses and the thickness of the corneal shape, but the impact is minimal. In the case of the hydrogel soft contact lenses (T2 lens) with low oxygen permeability, the corneal thickness showed distinct increasing patterns. The high order aberration and coma aberration were most changed in the silicon hydrogel toric lens, while the depth of anterior was most changed in the hydrogel toric lens. Conclusion: Among the 5 kinds of contact lenses with different water contents, materials, and refractive power used for this study, the corneal shape change was small for the lenses with an oxygen permeability (Dk) of more than 28, and the largest for the lenses with a very low oxygen permeability.

• The Journal of Advanced Prosthodontics
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• v.12 no.5
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• pp.283-290
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• 2020

PURPOSE. The present study aimed to evaluate the clinical applicability of monolithic zirconia (MZ) crowns of different thickness via determination of fracture resistance and marginal fit. MATERIALS AND METHODS. MZ crowns with 0.5, 0.8, 1.0, and 1.5 mm thickness and porcelain fused to metal (PFM) crowns were prepared, ten crowns in each group. Marginal gaps of the crowns were measured. All crowns were aged with thermal cycling (5 - 55℃/10000 cycle) and chewing simulator (50 N/1 Hz/lateral movement: 2 mm, mouth opening: 2 mm/240000 cycles). After aging, fracture resistance of crowns was determined. Statistical analysis was performed with one-way ANOVA and Tukey's HDS post hoc test. RESULTS. Fracture loads were higher in the PFM and 1 mm MZ crowns compared to 0.5 mm and 0.8 mm crowns. 1.5 mm MZ crowns were not broken even with the highest force applied (10 kN). All marginal gap values were below 86 ㎛ even in the PFM crowns, and PFM crowns had a higher marginal gap than the MZ crowns. CONCLUSION. The monolithic zirconia exhibited high fracture resistance and good marginal fit even with the 0.5 mm thickness, which might be used with reduced occlusal thickness and be beneficial in challengingly narrow interocclusal space.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.753-761
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• 2024

Introduction: In this study, TLD 600 and TLD 700 pairs were used to measure the neutron dose of Elekta Precise medical linac. To this end, the optimum moderate thickness for the conversion of fast to thermal neutrons were evaluated. Materials and methods: ²⁴¹Am-Be and ²⁵²Cf sources were simulated to calculate the optimum thicknesses of the moderator for the conversion of maximum fast neutrons (FN) into thermal neutrons (TN). Pair TLDs were used to measure F&TN doses for three different field sizes at four depths of the medical linac. Results: The maximum thickness of the moderator was optimized at 6 cm. The measurement results demonstrated that the TN dose increased with the expansion of field size and depth. The FN dose, which was converted TN, exhibits behaviors comparable to the TN due to its nature. Conclusion: This study presents the optimum thickness for the moderator to convert FN into TN and measure F&TN using TLDs.

• Imaging Science in Dentistry
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• v.53 no.2
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• pp.153-159
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• 2023

Purpose: The objective of this study was to assess the fractal dimension, lacunarity, trabecular microarchitecture parameters, and cortical linear measurements in the mandibles of male and female individuals to identify differences between them. Materials and Methods: In total, 116 cone-beam computed tomography scans of healthy individuals of different ages (57 men and 59 women, aged between 20 and 60 years) were selected. The following bone parameters were measured: 1) buccal, lingual, and basal cortical bone thickness in 5 standard parasagittal sections (the midline, the left and right sides of the lower lateral incisors, and the left and right sides of the lower canines); 2) the bone volume fraction of 10 sequential axial sections from each patient by creating a volume of interest in the area between the lower canines; and 3) fractal dimension and lacunarity using grayscale images of the same region of the volume of interest in the anterior mandible. Spearman correlation coefficients and the Mann-Whitney test were used. Results: A significant and positive correlation was found between age and cortical thickness, especially in the region of the central incisors. Significant differences between sexes in terms of fractal dimension, lacunarity, and bone volume were found. Women revealed lower fractal dimension values and higher lacunarity and bone volume ratio values than men. Conclusion: Fractal dimension, lacunarity, trabecular bone volume, and cortical thickness were different between men and women of different ages.

• Journal of Magnetics
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• v.18 no.4
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• pp.417-421
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• 2013

The dominant magnetization reversal behavior of electrodeposited CoPt samples with various thicknesses deposited at different current densities was the domain wall motion by means of wall pinning. The magnetic interaction mechanism was dipolar interaction for all samples. The dipolar interaction strength was significantly affected by the sample thickness rather than by the current density, while the magnetic properties were closely related to the current density.

• Transactions on Electrical and Electronic Materials
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• v.5 no.1
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• pp.24-28
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• 2004

We have used ITO/Alq$_3$/Al structure to study electrical conduction mechanism in organic light-emitting diodes. Current-voltage-luminance characteristics were measured at room temperature by varying the thickness of Alq$_3$ layer from 60 to 400mm. We were able to confirm that there are three different mechanisms depending on the applied voltage region; ohmic, space-charge-limited current, and trap-charge-limit-current mechanism. And the maximum luminous efficiency was obtained when the thickness of Alq$_3$ layer is 200nm.