• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.6
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• pp.589-593
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• 2015

The demand of high cycle fatigue behavior on plate material is increasing because of its various applications. However, the high-cycle fatigue life data of the plate material is very rare compared to the rod material. Thus, in this study, a plate specimen is designed for the ultrasonic fatigue test because it is time efficient as compared to the conventional fatigue test. To apply the ultrasonic fatigue test, the specimen design is required to resonate at 20 kHz. Therefore, the dynamic elastic modulus was determined by measuring the resonance frequency with a piezoelectric element and laser doppler vibrometer (LDV). As a result, the plate specimen is designed and demonstrated using the ultrasonic fatigue testing machine. The ultrasonic fatigue test results were compared with the hydraulic fatigue test results.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.5
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• pp.140-147
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• 2003

As the huge energy transfer systems like as nuclear power plant and steam power plant are operated for a long time at a high temperature, mechanical properties are changed and ductile-brittle transition temperature is raised by degradation. So it is required to estimate degradation in order to assess the safety, remaining life and further operation parameters. The sub-sized specimen test method using surveillance specimen was developed for evaluating the integrity of metallic components. In this study, we would like to present the evaluation technique of the ductile-brittle transition temperature by the sub-sized specimen test. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. The tensile test and fracture toughness test were performed. The results of the fracture toughness tests using the sub-sized specimens were compared with the evaluation technique of the ductile-brittle transition temperature.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.11
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• pp.84-90
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• 2007

In this study, design and manufacturing of plastic injection mold with cavity pressure/temperature sensors were performed fur tensile test specimen. International standard system for plastic tensile specimen was applied to design an injection molding system. Cavity pressure and temperature sensors were placed on the side of fixed platen of the injection mold to prevent them from external impact damage. Injection molding experiments with variations of injection speed and melt temperature were performed and then tensile test of the manufactured polycarbonate specimens was also performed. It was shown that injection molding processing parameters can have effect on the mechanical properties of the plastic injection molded part.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.579-584
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• 2001

As the huge energy transfer systems like as nuclear power plant and steam power plant are operated for a long time, mechanical properties are changed and ductile-brittle transition temperature is raised by degradation. So it is required to estimate degradation in order to assess the safety, remaining life, and further operation parameters. The sub-sized specimen test method using surveillance specimen was developed for evaluating the integrity of metallic components. In this study, we would like to present the evaluation technique of the ductile-brittle transition temperature by the sub-sired specimen test. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. The tensile test and fracture toughness test were performed. The results of the fracture toughness tests using the sub-sized specimens were compared with the evaluation technique of the ductile-brittle transition temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.2001-2005
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• 2005

The tensile test is generally used to measure mechanical properties with conventional fracture test. This test is extremely certain method to measure Young's modulus, yield strength, tensile strength and so on. ASTM, by international standard, prescribes two classes of tensile tests in tubular products. One is method that specimens aren't done by any process with Tube-shape. The other is that specimens are made on process for C-shape. In this paper, we would like to present the new-shape specimens for the tensile test. The presented specimen's shape is that put two pieces of C-shape specimens together. Besides a load point and a support point are fixed like Tube-shape specimens. This shape of specimen has a difference that existing specimen is made on one-step process out this specimen is made on two-step process. This shape is considered that stress concentration phenomenon occurs at the reduced section if a specimen is made on one step process.

• Earthquakes and Structures
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• v.12 no.1
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• pp.79-89
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• 2017

As a new type of energy dissipation component with excellent mechanical performance, the Buckling-Retrained Braces (BRBs) were gradually applied in retrofitting and improving seismic performance of reinforced concrete structures in China. In order to investigate the seismic performance of reinforced concrete structures retrofitted with BRBs, quasi-static test of two single-bay and 3-story reinforced concrete frames specimens was conducted and introduced in this paper. Two 1/2 scaled specimens were designed to reflect real prototype structure. For comparison, one control specimen was designed without BRBs, and the other specimen was retrofitted with BRBs. And particularly, for the specimen retrofitted with BRBs, the BRBs were eccentric layout instead of usually concentric or x-shaped layout, aiming to be more suitable for large-span frames. In the test, the failure mode, carrying capacity, deformability, ductility and energy dissipation ability of both two specimens were investigated. Based on the test results of the measured hysterical curves, skeleton curves, the seismic performances such as bearing capacity, plastic deformability, energy dissipation ability and ductility of two specimens were fully studied. And from the test results, it was indicated that the specimen retrofitted with BRBs showed much better seismic performance than the control specimen without BRBs, and the BRBs could effectively improve the seismic performance of the reinforced concrete frame. For the specimen retrofitted with BRBs, the BRBs firstly yielded before the beam-ends and the column-ends, and an expected yielding process or yielding mechanism as well as good seismic performance was obtained. For the specimens without BRBs, though the beam-ends yielded prior to the column-ends, the seismic performance was much poor than that of the specimen with BRBs.

• Journal of Technologic Dentistry
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• v.37 no.3
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• pp.107-113
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• 2015

Purpose: This study provided the basic data for selecting the zirconia blocks by comparing the mechanical properties of the all ceramic crown between the domestic, import, translucent and shade blocks that were used in clinically. Methods: Currently, the most commercial block of five types(one import and two domestic block which is the translucent and shade) were used. It were elucidated by means of three point bending test, hardness test, FE-SEM observations and EDX analysis. The results were analyzed using a one-way ANOVA and Scheffe post hoc test for significant findings. Results: For flexural strength, LT specimen was the highest as 733.1 MPa, followed by JT specimen(712.0 MPa), ZT specimen(646.0 MPa), LS specimen(553.1 MPa), JS specimen(429.0 MPa). One-way ANOVA showed statistically significant difference between groups for flexural strength(p<0.05). For hardness, ZT specimen was the highest as 1556.5 Hv, followed by JT specimen(1540.3 Hv), LT specimen(1512.3 Hv), JS specimen(1472.0 Hv), LS specimen(1353.3 Hv). One-way ANOVA showed statistically significant difference between groups for hardness(p<0.05). Conclusion: Domestic block was higher than import block for flexural strength, and translucent block was higher than shade block for flexural strength. However, all blocks showed clinically acceptable range. There was no significant difference in hardness between domestic and import blocks. And significant difference was observed in translucent and shade blocks.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.199-204
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• 2001

Big accidents of flyings, vessel, subways, gas equipments, buildings and bridge happens frenquently. Therefore many people are suffering harm of property. The destruction cause of macaine components is almost accused by fatigue. This study is test for STS304 specimen using pure and cantilever bending state. Rounded specimen and notched specimen including fracture surface investigation was comparatively experimented, fatigue life according to degree of surface finishing was examined. Fatigue fracture probability of notched canilever specimens were predicted by P-S-N curve, median rank and Weibull distribution. And at the relation with the rotational speed and stress, the fatigue life of the test specimen was higher at high speed than low speed.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.132-137
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• 2001

Miniaturized specimen technology is useful to characterize the mechanical behavior using a minimum volume of material, because it is almost impossible to sample the conventional specimen for the fracture toughness test without damage to equipment. Test material was 1Cr-1Mo-0.25V steel which was widely used for turbine rotor material. Two kinds of miniaturized impact specimens were prepared, i.e., miniaturized specimen with side groove and without side groove. The correlation between ductile brittle transition temperature(DBTT) of full size impact specimen and that of miniaturized impact specimen was made. The characteristics of miniaturized impact specimens technique as well as fracture stress were discussed. Finally, we concluded that the characteristics of fracture stress change on aging time were similar to that of DBTT.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.831-835
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• 2008

Recently, the use of C.S.G is gradually increasing as the construction material for dam, road, revetment and so on. The strength characteristics of C.S.G is affected by various influence factors such as specimen size, maximum grain size and water contents. Therefore, When designing and constructing the C.S.G structure, it is very important for us to understand the nature of used materials well and to test it's quality. Commonly, C.S.G strength test is used the cylinders specimen size of $15{\times}30$ at KS F2405. But, the specimen size extracted from the field structure is not regular. This paper aims at offering the experimental data about the compressive strength and elasticity modulus by change of the specimen size for the effective quality control of the C.S.G structure.