• Restorative Dentistry and Endodontics
• /
• v.44 no.4
• /
• pp.45.1-45.10
• /
• 2019

Objectives: Self-adhesive resin cements contain functional monomers that enable them to adhere to the tooth structure without a separate adhesive or etchant. One of the most stable functional monomers used for chemical bonding to calcium in hydroxyapatite is 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP). The aim of this study was to evaluate the influence of the10-MDP concentration on the bond strength and physical properties of self-adhesive resin cements. Materials and Methods: We used experimental resin cements containing 3 different concentrations of 10-MDP: 3.3 wt% (RC1), 6.6 wt% (RC2), or 9.9 wt% (RC3). The micro-tensile bond strength of each resin cement to dentin and a hybrid resin block (Estenia C&B, Kuraray Noritake Dental) was measured, and the fractured surface morphology was analyzed. Further, the flexural strength of the resin cements was measured using the three-point bending test. The water sorption and solubility of the cements following 30 days of immersion in water were measured. Results: The bond strength of RC2 was significantly higher than that of RC1. There was no significant difference between the bond strength of RC2 and that of RC3. The water sorption of RC3 was higher than that of any other cement. There were no significant differences in the three-point bending strength or water solubility among all three types of cements. Conclusions: Within the limitations of this study, it is suggested that 6.6 wt% 10-MDP showed superior properties than 3.3 wt% or 9.9 wt% 10-MDP in self-adhesive resin cement.

• Composites Research
• /
• v.30 no.2
• /
• pp.158-164
• /
• 2017

The fiber metal laminate is a type of hybrid materials laminated thin metallic sheets with fiber reinforced plastic sheets. The laminate has been researched or applied in automotive and aerospace industries due to their outstanding impact absorbing performance in view of light weight aspect. Specially, the replacement of side-impact beam as the fiber reinforced plastic has been researched actively. The objective of this paper is the primitive investigation in the development of side-door impact beam using the fiber metal laminate. First, the three-point bending simulations were conducted to decide the shape of impact beam using the numerical analysis. Next, two cases impact beam (pure DP 980 and fiber metal laminate) were installed in the side-door, and then the bending tests (according to FMVSS 214S) were simulated using the numerical analysis. It is noted that the side-door impact beam can be replaced with the fiber metal laminate sufficiently based on the numerical analysis results.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1995.04a
• /
• pp.257-262
• /
• 1995

In this study, after concrete cylinders were made on the condition of varying water-to -cement ratio, and cured 80 days compressive strength and splitting tensile strength were performed and moduls of elasticy is obtained. The fracture energy was obtained by acting three point bending on the 80cm in length. This test involved static loading test and dynamic loading test. In this work, the new interrelation of the material constants was obtained clearly and the property of the mixture was inspected, including the relation between the fracture energy and all kind of the material constants.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.1525-1529
• /
• 2003

This paper describes the result of carbody load test. The purpose of the test is to evaluate an safety which carbody structure shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load and operating condition. Carbody material applied a stainless steel and an aluminum alloy, The stainless steel model is the carbody of a motor car which is delivering to KNR line 1 in 2002 and the aluminum alloy model is the carbody of a motor car which is delivering to GWANGJU line 1 in 2003.

• Tribology and Lubricants
• /
• v.15 no.2
• /
• pp.141-149
• /
• 1999

Fracture, fatigue and wear characteristics of Al-Si alloy used for compressor are experimentally studied. Plane strain fracture toughness test is carried out using three point bending specimen. Fatigue test is performed under constant loading condition and wear test is carried out as a function of sliding velocity and applied load. To obtain the crack propagation characteristics and wear mechanism of Al-Si alloy, fracture and worn surfaces are investigated using SEM. It is verified that fracture and fatigue strength of Al-Si alloy are improved by the fine microstructure of alloy. The wear behavior and specific wear amount of Al-Si alloy are not dependent on the microstructure but on a function of the silicon content. Anodizing on the surface of Al-Si alloy, surface hardness and wear characteristics are improved.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.13 no.1
• /
• pp.136-146
• /
• 2021

This paper aims to numerically estimate the dynamic ice load on a conical structure. The Discrete Element Method (DEM) is employed to model the level ice as the assembly of numerous spherical particles. To mimic the realistic fracture mechanism of ice, the parallel bonding method is introduced. Cases with four different ice drifting velocities are considered in time domain. For validation, the statistics of time-varying ice forces and their frequencies obtained by numerical simulations are extensively compared against the physical model-test results. Ice properties are directly adopted from the targeted experimental test set up. The additional parameters for DEM simulations are systematically determined by a numerical three-point bending test. The findings reveal that the numerical simulation estimates the dynamic ice force in a reasonably acceptable range and its results agree well with experimental data.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.1
• /
• pp.605-611
• /
• 2023

In this study, in order to reduce energy that affects the natural environment, a moving iron core type welding machine and a digital welding machine (inverter type) with low power consumption are compared in shielded arc welding, and the parts that use less power and have the same weldability conditions are identified. want to check. The movable iron core welder uses alternating current that outputs a sine wave, and the digital welder also generates a sine wave alternating current, so it must have the same conditions, low power consumption, and the same weldability. However, weldability can be verified in various ways, but the analysis is limited to the qualification test in the field of national technical qualification welding.

• Journal of the Korean Ceramic Society
• /
• v.39 no.7
• /
• pp.675-679
• /
• 2002

To produce a strengthened glass, single ion exchange properties such as three-point bend strength and residual stress were investigated in soda-lime-silicate substrate glass for display use. The present work showed that the maximum value of strength was 62.5${\times}$10$\sub$6/ kg/㎡ after, the two-step single ion exchange process at 470$^{\circ}C$ for 1 h and 450$^{\circ}C$ for 24 h. As the result of the fracture analysis after bending test, the residual stress on the fractured surface of the strengthened glass increased the flexibility by means of absorbing the elastic deformation energy in the glass. Also, the effects of absorbing the elastic deformation energy were analysed by curvature change, number of multiple crack branches and brittleness.

• Corrosion Science and Technology
• /
• v.19 no.2
• /
• pp.51-56
• /
• 2020

The objective of this study was to improve properties of plasma sprayed HAp layer to titanium substrate by introducing an intermediate layer with two different methods. Before applying Zn doped HAp coating on titanium substrate, an intermediate layer was introduced by titanium plasma spray or titanium anodization. Heat treatments were conducted for some samples after titanium intermediate layer was formed. Zn doped HAp top layer was applied by plasma spraying. Three-point bending test and pull-off adhesion test were performed to determine the adhesion of Zn doped HAp coatings to substrates. Long-term credibility of Zn doped HAp plasma sprayed coatings on titanium was assessed by electrochemical impedance measurements in Hanks' solution. It was found that both titanium plasma sprayed and titanium anodized intermediate layer had excellent credibility. Strong adhesion to the titanium substrate was confirmed after 12 weeks of immersion for coating samples with titanium plasma sprayed intermediate layer. Samples with titanium anodized intermediate layer showed good bending strength. However, they showed relatively poor resistance against pulling off. The thickness of titanium anodized intermediate layer can be controlled much more precisely than that of plasma sprayed one, which is important for practical application.

• Journal of the Korean Society of Safety
• /
• v.38 no.3
• /
• pp.20-26
• /
• 2023

Fiber-reinforced composite materials with carbon, glass, and aramid fibers are widely applied to industrial field structures due to their excellent properties. However, carbon fibers are vulnerable to external impacts, whereas aramid fibers degrade when exposed to water. This study evaluated carbon/aramid fiber composites degraded and damaged by high-temperature saline environments using acoustic emission (AE). The test specimen was molded using an autoclave and immersed in seawater at 70 ℃ for 224 days. In order to imitate the damage, a 3-mm-diameter hole was drilled using a diamond drill. Additionally, the specimen with the perforation was repaired by patch attachment processing. Three-point bending was used to conduct the flexural experiment, and an AE sensor with a 150-kHz resonance frequency was attached to evaluate the damage and the effect of patch attachment. AE accumulative counts obtained at the maximum load were 69.2, 67.1, and 91.2 for a high-temperature seawater deteriorated condition, a hole specimen, and a repaired patch specimen, respectively. Furthermore, the maximum amplitude of AE was detected at low values of 28 dB, 31.3 dB, and 30.3 dB.