• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.371-374
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• 2003

The corrosion of steel reinforcing bar(re-bar) has been the major cause of the reinforced concrete deterioration. FRP(Fiber-reinforced polymer) reinforcing bar has emerged as one of the most promising and affordable solutions to the corrosion problems of steel reinforcement in structural concrete. In this study, long-term durability performance of FRP re-bar were evaluated. The mechanical and durability properties of two type of CFRP- and GFRP re-bar were investigated; the FRP re-bars were subjected to alkaline solution, acid solution, salt solution and deionized water. The mechanical and durability properties were investigated by performing tensile and short beam tests. Experimental results confirmed the desirable resistance of FRP re-bar to aggressive chemical environment.

• 한국신뢰성학회지:신뢰성응용연구
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• 제11권1호
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• pp.31-41
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• 2011

A strut mount is an important part of vehicles which reduces the vibration and the impact transmitted from the wheels while supporting a shock absorber and a coil spring. Rubber compounding, shape design, and process design technologies are important components to improve the functionality of a strut mount such as durability, static, dynamic, and torsional characteristics. Among them the rubber compounding technology is the key technology which dominates the quality of a strut mount. In this study a strut mount with high reliability has been developed by adopting new rubber compounding and improving the shape of the inner plate and the isolator. Through the tests for prototypes it has been shown that the durability has been improved more than 2.5 times, from about 60,000 cycles to about 160,000 cycles.

• 한국자동차공학회논문집
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• 제3권6호
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• pp.154-161
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• 1995

There are several kinds of driving conditions according to the characteristic of each vehicle diver. Automaker produces vehicle strong enough to satisfy this several driving conditions at the point of vehicle durability. In order to develop the car in a short period, Automaker engineer tests vehicle at serveral accelerated durability test roads. Before testing the vehicle durability, test engineer must know how much this test road severe than general field road which is composed of high way, city road, paved road and unpaved road. This paper suggests two types of road severity test method that is using relative fatigue life prediction method and using absolute fatigue life prediction method, and also present the merits and demerits of two test methods.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 추계학술대회 논문집
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• pp.24-29
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• 1998

To absorb the deformation of ,external live load, thermal gradient, shrinkage and creep in bridge structures and general structures, expansion joint has to be established. Especially expansion joint for high-speed railway bridge has to accomodate the static and dynamic forces and it not only has the durability of itself but also maintain the durability of structure by preventing the leakage of water. The actual used product of expansion joint for high-speed railway bridge is only ones made in France, Germany and Japan. In this study, the development process and test results of developed expansion joint are introduced which has the functional operation and durability enough to apply to high-speed railway bridges, roadway bridges and general structures. The tests consist of fatigue-durability test of 3 million times by high-speed rail load, leakage test and jack-up test for verifying the possibility of exchanging it. The performance of developed expansion joint satisfy the specification of Korea High Speed Rail Construction Authority.

• 지질공학
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• 제27권4호
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• pp.451-462
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• 2017

Physical weathering caused by external forces and chemical weathering caused by the decomposition or alteration of constituent materials are the two factors that dominate the mechanical properties of rocks. In this study, a field investigation was undertaken to identify the physical and chemical weathering characteristics of the biotite granite and granitic weathered soils in Gyeongju, South Korea. Samples were collected according to their grade of weathering and subjected to modal analysis, XRD analysis, XRF analysis, physical property tests, particle size distribution tests, and slake durability tests. Modal and XRD analysis identified these rocks as biotite granite; secondary alteration minerals were not observed. Physical property tests and particle size distribution analyses indicate an average porosity of 41.28% and a sand content of > 90 wt.%. These values are somewhat higher than those of granites in general. The results of the slake durability test and XRF analyses show that the physical and chemical weathering indices of the samples vary with the degree of weathering.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집 특별세미나,특별/일반세션
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• pp.421-426
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• 2009

Recently, the design process for a railway bogie frame in Europe has been carried out according to the norm EN 13749. The activities in the norm EN shall demonstrate that the design of the bogie frame fulfills the acceptances of 4 steps of the program such as structural calculation, static tests, fatigue test and on-tracks tests. At the end of the acceptance program, the on-tracks tests have the aim to measure the real stress history generated in operation and to verify that they are reasonably next to those calculated and measured on the test rig. Therefore, in order to assure the safety of the railway vehicle, it is important to examined the durability of that under load histories measured from on-tracks tests. In this study, under variable amplitude loading based on the actual acceleration history, fatigue analysis of the welding bogie frame is investigated by using durability software. Moreover, the fatigue life of the frame under the loading in the norm EN fatigue test condition is evaluated and compared with the life under variable amplitude loading.

• 한국농공학회논문집
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• 제58권1호
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• pp.19-26
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• 2016

This study was performed to evaluate the strength and durability properties of modified epoxy composites with waste tire chip, recycled coarse aggregate, filler and modified epoxy to improve elongation and elasticity of epoxy. Additionally, for comparing to modified epoxy and unsaturated polyester resin as a binder, unsaturated polyester resin composites were developed in the same condition. The mix proportions were determined to satisfy the requirement for the workability and slump according to aggregate size and binder content. Tests for the compressive and flexural strength, freezing and thawing and durability for 20 % sulfuric solution were performed. The compressive and flexural strength of modified epoxy composites were in the range of 34.9~61.6 MPa and 10.2~18.3 MPa at the curing 7 days, respectively. Also, the compressive and flexural strength of unsaturated polyester resin composites were in the range of 44.2~77.8 MPa and 11.3~20.8 MPa at the curing 7 days, respectively. After 300 cycles of freezing and thawing, weight decrease ratio and durability factor of modified epoxy composites were in the range of 0.8~1.9 % and 95~98, respectively. Accordingly, modified epoxy composites will greatly improve the durability of concrete.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 추계 학술논문 발표대회 논문집
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• pp.151-154
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• 2006

It is generally referred that life cycle of concrete construction is depend on whether durability of concrete is obtained or not. Nevertheless, it has not been yet applied that new material and technology to improve durability of concrete such as seaside concrete construction. In this study, chemical agent which is capable of improving durability added to 2 types seaside concrete mixs and evaluated engineering properties such as slump, air content, setting time and compressive strength. Besides shrinkage crack with an restraint condition and chloride ion penetration tests were executed to measure resistance of concrete added chemical agent and then compared non-added. It was appeared that engineering properties and resistant for chlorides was possible to improved. But resistant for shrinkage crack was not noticeable improvement than non-added. Therefore it is necessary that more consideration and following study to improve durability aspect to shrinkage crack and chlorides resistant.

• Computers and Concrete
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• 제15권4호
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• pp.589-606
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• 2015

It is well-documented that the major deterioration of coastal RC structures is chloride-induced corrosion. Therefore, regional investigations are necessary for durability based design and evaluation of the proposed service life prdiction models. In this paper, four reinforced concrete jetties exposed to severe marine environment were monitored to assess the long term chloride penetration at 6 months to 96 months. Also, some accelerated durability tests were performed on standard samples in laboratory. As a result, two time-dependent equations are proposed for basic parameters of chloride diffusion into concrete and then the corrosion initiation time is estimated by a developed probabilistic service life model Also, two famous service life prediction models are compared using chloride profiles obtained from structures after about 40 years in the tidal exposure conditions. The results confirm that the influence of concrete quality on diffusion coefficients is related to the concrete pore structure and the time dependence is due to chemical reactions of sea water ions with hydration products which lead a reduction in pore structure. Also, proper attention to the durability properties of concrete may extend the service life of marine structures greater than fifty years, even in harsh environments.

• 한국의류학회지
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• 제42권3호
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• pp.474-485
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• 2018

Smart sensors and connected devices have changed the concept of garments along with IT technology convergent garments that transform the performance of basic functions. Various types of products have been researched and developed due to the increased interest in smart clothing; in addition, studies based on physical and mechanical properties have also been actively studied to improve accuracy and reliability. This study represents a basic study for the development of smart textiles based on motion recognition for the surfing practice of beginners interested in IT convergence type. A physical durability evaluation of conductive yarn according to sewing method was later carried out. This study is a conditional specimen sewn with cotton lower thread and 100mm pattern length based on the results of previous studies. The durability of the conductive yarn according to the sewing method was evaluated according to the sewing method. Durability was evaluated by two kinds of repeated strain and abrasion tests. The specimen with applied cotton in a lower thread zigzag pattern 2mm stitch size 100mm stitch length was shown to have the most suitable durability for smart textile.