• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.610-615
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• 2001

In the interest of improved automotive fuel economy, one solution is reducing vehicle weight. Achieving significant weight reductions will normally require reducing the panel thickness or using alternative materials such as aluminum alloy sheet. These changes will affect the dent resistance of the panel. In this study, the correlation between panel size, curvature, thickness, material properties and dent resistance is investigated. A parametric approach is adopted, utilizing a "design software" tool incorporating empirical equations to predict denting and panel stiffness for simplified panels. The developed design program can be used to minimize panel thickness or compare different materials, while maintaining adequate panel performance.

• The Journal of Advanced Prosthodontics
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• 제4권2호
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• pp.93-96
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• 2012

PURPOSE. The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. MATERIALS AND METHODS. A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical significance was determined using two-way ANOVA (${\alpha}$=.05). RESULTS. ANOVA revealed that thickness of zirconia and light curing unit had significant effects on light transmittance ($P$ <.001). CONCLUSION. Greater thickness of zirconia results in lower light transmittance. Light-emitting diodes light-curing units might be considered as effective as Plasma arc light-curing units or more effective than Quartz-tungsten-halogen light-curing units for polymerization of the resin-based materials.

• Nuclear Engineering and Technology
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• 제53권5호
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• pp.1634-1641
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• 2021

Exposure to gamma-rays is hazardous for humans and other living beings because of their high penetration through the materials. For this reason, shielding materials (usually lead, copper and stainless steel) are used to protect against gamma rays. This study's objective was to prepare ceramic materials for gamma radiation shielding by using different natural bentonite clays. Gamma-ray attenuation performances of the prepared shielding materials at different thicknesses were investigated and evaluated for different gamma-ray energies from different standard point gamma radiation sources (²⁵¹Am, ⁵⁷Co, ¹³⁷Cs, ⁶⁰Co, and ⁸⁸Y). The mass and linear attenuation coefficients of the prepared ceramics vary between 0.238 and 0.443 cm² g^-1 and between 0.479 and 1.06 cm^-1, respectively, depending on their thicknesses. Results showed that these materials could be prioritized because of their evidential properties of gamma radiation protection in radiation applications.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1996년도 제23회 학술대회
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• pp.30-35
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• 1996

An elastohydrodynamic lubrication (EHL) analysis for an axially crown profiled cylindrical roller is carried out using a finite difference method and the Newton-Raphson method. Variations of the minimum film thickness with dimensionless parameters show considerably different from those of infinite solutions.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1997년도 춘계학술대회논문집
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• pp.117-120
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• 1997

Microstructure and pole figure through thickness in cold rolled sheet steel were investigated. The calculated plastic strain ratio in surface is greatly different with that in center layer and measured value in tensile test.

• 한국안전학회지
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• 제13권4호
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• pp.79-86
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• 1998

The effect of specimen thickness on fatigue crack growth behavior has been carried out by compact tension specimens of thickness of 3mm, 10mm and 25mm for maraging steel and Al 7075-T6. The closure points were determined during the test by means of a clip-gage situated at the notch mouth. Specimen thickness have no apparent influence on the fatigue crack growth rate of maraging steel, but the crack growth rate of 25mm thickness specimen for Al 7075-T6 is faster than that of 3 and 10mm specimens. The difference of crack growth rates can be successfully explained by considering the different stress state of plane strain and plain stress due to the variation of specimen thickness. Also the crack opening ratio of 25mm specimen is greater than those of 3 and 10mm specimens. When a side groove is introduced in a 10mm specimen, the crack growth rate is approximately similar to that of 25mm specimen. The effective thickness expression of $B_e=B_o-(B_o-B_N)^2B_o$ is the most appropriate to evaluate the crack growth rate of side-grooved specimen. Fatigue crack growth rates can be well described by $\Delta K_{eff}$ of the crack closure points in regardless of all thickness and side-grooved specimens.

• 한국전기전자재료학회논문지
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• 제24권3호
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• pp.215-218
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• 2011

A novel design of gas sensor using Ga-doped ZnO (GZO) thin films which are deposited on low temperature co-fired ceramic (LTCC) substrates is presented. The LTCC substrates with thickness of 400 ${\mu}m$ are fabricated by laminating 12 green tapes which consist of alumina and glass particle in an organic binder. The GZO thin films with different thickness are deposited on LTCC substrates, by RF magnetron sputtering method. The microstructure and sensing properties of GZO gas sensing films are analyzed as a function of the film thickness. The films are well crystallized in the hexagonal (wurzite) structure with increasing thickness. The maximum sensitivity of 3.49 is obtained at 100 nm film thickness and the fastest 90% response time of 27.2 sec is obtained at 50 nm film thickness for the operating temperature of $400^{\circ}C$ to the $NO_2$ gas.

• 대한치과교정학회지
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• 제51권2호
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• pp.135-141
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• 2021

Objective: To assess the effects of thermoforming on aligner thickness and gap width in six aligner systems with the same nominal thickness. Methods: Six passive upper aligners of different brands were adapted to a single printed cast. Each sample was evaluated with high-resolution micro-computed tomography. To investigate aligner thickness and gap width, two-dimensional (2D) analysis was conducted assessing the effects of the following variables: tooth type (central incisor, canine, and first molar), 2D reference points, and aligner type. Data were analyzed and compared using analysis of variance and Tukey's post-hoc tests (p < 0.05). Results: Tooth type, dental region, and aligner type affected both the gap width and aligner thickness. The aligner thickness remained moderately stable across the arch only in the F22. Conclusions: All thermoformed samples displayed smaller aligner thickness and gap width at anterior teeth and both gingival and coronal centers than at posterior teeth and occlusal surfaces.

• Journal of Periodontal and Implant Science
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• 제31권3호
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• pp.641-649
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• 2001

The aim of present study was to assess the thickness of masticatory mucosa on the hard palate and tuberosity as a potential donor site for mucogingival surgery. Thickness measurement was performed in 30 dental college students who are periodontally healthy, with a recently developed, ultrasonic device(SDM). The mean age of study subjects was 23.7(range 21-29) years old and the subjects were composed of 18 males and 12 females. Eighteen standard measurement points were defined on the hard palate, located on 3 lines which ran at different distances parallel to the gingival margin. Six positions were designated on each of these 3 lines between the level of the canine and the second molar. On the tuberosity, 6 standard measurement points were defined, located on 2 lines running parallel to the gingival margin at different distances. Data were analyzed to determine differences in gender, between different positions, and between lines, by an analysis of variance. The results showed that the mucosa of the tuberosity was significantly thicker than that of the hard palate region. Gender did not influence the thickness of masticatory mucosa, either on the hard palate or the tuberosity. On the hard palate, mucosa thickness increased as the distance from the marginal gingiva increased. The mucosa over the palatal root of the maxillary first molar was significantly thinner than that at all other positions on the hard palate. Measurement error at palate was 0.25mm, at tuberosity 0.51mm. No difference in the thickness of masticatory mucosa on palate and tuberosity was found between men and women. On the hard palate, soft tissue thickness progressively increased in sites further from the gingival margin. Therefore, we may harvest more thicker graft on the tuberosity that has more masticatory mucosa thickness than hard palate, however the width may not be sufficient for using.

• Journal of the Korean Wood Science and Technology
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• 제45권3호
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• pp.335-342
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• 2017

본 연구는 제재과정에서 발생하는 톱밥과 농업부산물인 귤박의 새로운 활용 방안을 찾기 위하여 수행되었다. 귤박 혼합율 및 밀도별로 혼합보드를 제조한 후 수지함침율, 탄화온도 및 귤박혼합율별로 세라믹화 하여 물리적 성질을 조사하였다. 수지함침율이 증가할수록 두께와 길이감소율 및 밀도는 증가하였고, 중량감소율은 감소하였다. 탄화온도가 증가할수록 중량감소율은 증가되었고, 길이와 두께 감소율은 $1000^{\circ}C$까지 증가하고 그 이후의 증가는 완만하였다. 귤박혼합율이 높을수록 중량과 두께 및 길이 감소율은 감소하였다.