• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.885-886
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• 2006

Significant advances in mechanical testing for hard materials are discussed in this paper. There are three specific areas that are covered. In the measurement of fracture toughness factors such as the control of slow crack growth to produce strating cracks, and evaluating reproducibility and repeatability of tests have been recently examined. The miniaturization of tests reduces the amount of material that is used in testing, improves the throughput of tests, and also improves cost effectiveness. New techniques such as stepwise testing and micro scratch testing have contributed to significant additions to the knowledge of the wear mechanisms that operate in these materials.

• Journal of the Korea Safety Management & Science
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• v.3 no.1
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• pp.127-137
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• 2001

Because of the inherent flexibility in their design for improved material properties, composites have wide applications in aerospace vehicles and automobiles. The purpose of this study is to investigate the energy absorption characteristics of CFRf (Carbon Fiber Reinforced Plastics) tubes on static and impact tests. Static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine) and impact compression tests have been carried out using the vertical crushing testing machine. When such tubes were subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that control the crushing process. The collapse characteristics and energy absorption were examined. Trigger and interlaminar number affect the energy absorption capability of CFRP tubes.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.359-364
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• 2004

We investigated the effect of weld details on fatigue behavior of a material, JIS SM 490 A, with yielding strength of about 350 MPa and tensile strength of about 520 MPa. Tensile tests, instrumented indentation tests and fatigue tests were carried out on double V-grooved butt weld plates such as reinforcement removed, as-welded and weld toe ground. In addition plates with transverse fillet welded web, load carrying cruciform fillet welded plates, non-load-carrying cruciform fillet welded plates and longitudinal butt welded plates were tested. S-N curves for the above specimens were obtained and analyzed

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.596-600
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• 2002

To analyze the settlement characteristics of short-fiber reinforced soil(SFRS), which will be used as a new backfill material of reinforced retaining wall, under simulated railroad loading, a series of tests with loading condition of 5 Hz frequency and 500,000 cycles were performed. The materials used for tests are soils with SM or ML type, and polypropylene short-fibers with mono-filament(PPM) or fibrillated type(PPF). From the tests, average plastic settlement is low at PPF38(0.3%)(abbreviation of PPF with 38mm length and mixing ratio 0.3%), PPF38(0.5%), PPM60(0.2%) for SFRS using SM soil and at PPF38(0.3%), PPF60(0.2%) for SFRS using ML soil. Elastic settlement is low at PPM60(0.2%) for SFRS using SM soil and at PPM60(0.5%) for SFRS using ML soil.

• Journal of Ocean Engineering and Technology
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• v.13 no.1 s.31
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• pp.94-104
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• 1999

In order to evaluate the performance of axially of laterally loaded piles experimentaly, pile load tests can be carried out at the site Otherwise stress analyses or subgrade reaction analyses can solve the problem. In this study, stress analysis using FLAC code and subgrade reaction analyses using load transfer curves recommended by API(1993) were performed consistently on the basis of a result of site investigations, and the result of analyses was compared with the measured. As a result the behavior of pile heads was analyzed accurately for both axially and laterally loaded tests. Furthermore axially transferred loads were calculated appropriately for the measured and axial loads were transferred mainly mainly by the frictional resistance rather than by the tip resistance. Consequently, it can be commented that both analysis methods of soil-pile systems are applicable at teh objective site and that solutions may be more accurate if material properties from the site investigation are more explicit.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.553-557
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• 1996

Heat cycle aging of insulating materials in large generator stator winding has been investigated using both on-line and off-line test methods. On this study, principally, off-line test against actual generator in service was carried out to acquire information about polarization index(PI) and dissipation factor, dissipation factor tip-up, maximum partial discharge for the purpose of remnant breakdown voltage and life assessment. It was found from the tests that both dissipation factor and maximum partial discharge decreased with the increase of operating hours and starting numbers. It was found from off-line tests that the remnant breakdown voltage had a strong relationship with both dissipation factor and maximum partial discharge the remnant breakdown voltage as a results of both operating hours and starting number and the nondestructive tests were proposed as parameters which can predict the remnant lifetime of insulating materials in large generator stator windings. (author). 8 refs., 8 figs., 2 tabs.

• Journal of Surface Science and Engineering
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• v.36 no.6
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• pp.475-479
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• 2003

In this study, to investigate the effects of 2-step shot peening at the surface of spring steel, tests are conducted on spring steel and shot peened specimens. Various tests are accomplished to evaluate mechanical properties influenced by shot peening process, and fatigue tests are also performed to evaluate the improvement of fatigue strength. And then the residual stresses are examined. The mechanical properties of material did not change so much by shot peening. However, the fatigue strength of notched specimen remarkably increased. In the case of 1-step shot peening, fatigue strength increased by about 20％ than unpeened specimen. Especially, in the case of 2-step shot peening, fatigue strength increased by about 40％, because the residual compressive stress at surface was higher than that of 1-step shot peened specimen. The fatigue strength and life are closely related to the value and position of maximum compressive residual stress by shot peening.

• Journal of Ship and Ocean Technology
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• v.7 no.1
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• pp.1-12
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• 2003

Stiffened plates are among the most popular structural elements for marine structures like ships or offshore platforms. Many researchers have performed and reported the results of structural tests on stiffened plates in the open literature. However, the behaviour of stiffened plates in post-ultimate regime has not been fully reported. This paper reports the results of twenty-one axial compression tests including the initial imperfections and material properties of the test models. In aiming to investigate the post-ultimate behaviour of stiffened panels, the axial shortenings were increased up to far beyond the ultimate state. The results obtained from these tests can be utilized in substantiating design formulae in predicting the post-ultimate behaviour of stiffened plates.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.430-435
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• 2008

Hyundai-Rotem Company has designed and manufactured Light Railway Vehicle (LRV) according to the Urban Rail Transit Code, which applies to urban railway vehicles in Korea. The Urban Rail Transit Code specifies the loads, for which vehicle bodies shall be capable of withstanding, identifies how material data shall be used and presents the principles to be used for design verification by analysis and test. The structural design of railway vehicle bodies depends on the loads they are subjected to and the characteristics of the materials they are manufactured from. Therefore Hyundai-Rotem Company has carried out Finite Element Analysis (FEA) and has performed load tests on the vehicle body according to the Urban Rail Transit Code. This research contains the results obtained by the analysis and the load tests. The analysis was carried out using I-DEAS Master Series 12 and load test were carried out using specially designed test jigs and equipment are used for the load tests.

• Metals and materials international
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• v.24 no.6
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• pp.1249-1255
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• 2018

High temperature compression tests for newly developed Al-Zn-Mg alloy were carried out to investigate its hot deformation behavior and obtain deformation processing maps. In the compression tests, cylindrical specimens were deformed at high temperatures ($300-500^{\circ}C$) and strain rates of 0.001-1/s. Using the true stress-true strain curves obtained from the compression tests, processing maps were constructed by evaluating the power dissipation efficiency map and flow instability map. The processing map can be divided into three areas according to the microstructures of the deformed specimens: instability area with flow localization, instability area with mixed grains, and stable area with homogeneous grains resulting from continuous dynamic recrystallization (CDRX). The results suggest that the optimal processing conditions for the Al-Zn-Mg alloy are $450^{\circ}C$ and a strain rate of 0.001/s, having a stable area with homogeneous grains resulting from CDRX.