• Proceedings of the KSR Conference
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• 2005.11a
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• pp.854-859
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• 2005

The major objective of this study is to investigate the dynamic behaviors of track due to the deterioration characteristics of ballast for servicing tracks by the field test. The durability of ballast plays an important role in the track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several shcolars. The deterioration characteristics of ballast is one of the most important factor in the dynamic behaviour of track and its life. In this paper abrasion/breakage characteristics of ballast is studied to predict the effect of physical ballast characteristics on ballast track. To reveal deterioration characteristics of ballast, the field test were carried out. The deterioration characteristics, studied in this paper, is applied to the dynamic behaviour of track in various conditions.

• The International Journal of Costume Culture
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• v.3 no.2
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• pp.147-160
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• 2000

The purposes of the present study were to investigate the factors of consumer dissatisfaction with backpacks and to examine if the levels of dissatisfaction with the factors differ significantly among the groups determined by demographic characteristics and purchase behaviors. The differences in the purchase behaviors of backpacks were also tested among the groups determined by demographic characteristics. Data collection was consisted of two pilot tests and the final test. The questionnaire was distributed to 40 students of universities in Seoul from July 1 to 13 in 2000 and 351 were usable. Data were analyzed by factor analysis, t-test, χ²analysis, MANOVA, ANAOVA, Duncan's multiple range tests using SPSS PC/sup +/ Program. Five factors were formulated : durability, ease-of-care/color fastness, dimensional stability, wearability and design. Subjects were most dissatisfied with the dimensional stability of backpacks. Different demographic characteristics and purchase behaviors resulted in significantly different levels of dissatisfaction with selected factors. Significant differences were also found in selected selection criteria and purchase behaviors among groups determined by some demographic characteristics.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.494-507
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• 2006

The major objective of this study is to investigate the dynamic behaviors of track due to the deterioration characteristics of ballast for servicing tracks by the field test. The durability of ballast plays an important role in the track behaviour. To estimate the deterioration characteristics of ballast, several tests have been carried out by several scholars. The deterioration characteristics of ballast is one of the most important factor in the dynamic behaviour of track and its life. In this paper abrasion/breakage characteristics of ballast is studied to predict the effect of physical ballast characteristics on ballast track. To reveal deterioration characteristics of ballast, the field test were carried out. The deterioration characteristics, studied in this paper, is applied to the dynamic behaviour of track in various conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.3
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• pp.66-72
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• 1999

The purpose of this experiment is to estimate freezing and thawing resistance of rice straw ash concrete. Test results show that mass, pulse velocity and relative synamic modulus of elasticity are gradually decreased with increase of freezing and thawing cycle. The durability factor(DF) is in the range of 85.48 ∼86.33 in the rice straw ash comcrete with 2.5% , 5% 7.5%, rice straw ash and higher than that of thenormal cement concrete. But, DF of 10% , 12.5%, 15% rice straw ash filled rice straw ash concrete is in the range of 41.26∼65.34 and lower than that of the normal cement concrete.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.188-193
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• 2007

Magnetic contactors (MCs) are widely used in industrial equipment such as elevators, cranes and factory control rooms in order to close and open the control circuits. The reliability of MCs mainly depend on mechanical durability and international standards such as IEC 60947-4-1, which stipulates the testing method for MCs. Testing time, however, is so long in usual cases that a method of reducing testing time is required. Therefore, a temperature and voltage-accelerated life testing (ALT) method has been developed to reduce the testing time in this work. The accelerated life test data are analyzed and acceleration factors (AFs) are provided.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.935-940
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• 2008

To maintain the primary stage of design, it is not too much to say that drainage systems should has been to maintain the most factor in earthwork structures. The durability of earthwork structures has about over 90 years as like concrete structures and has easily used to construction materials. Even if is a good earthwork materials, it hasn't lose design life at inadequate drainage system. In case of railway was frequently performed a maintenance works after construction 5 years because embankment site hasn't installed a concrete duck. In this study, the drainage standard of railway reviews the technological levels of drainage system by comparing the code for design of railway and road.

• International conference on construction engineering and project management
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• 2013.01a
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• pp.235-242
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• 2013

With the recent global trends in environmental preservation, the importance of sustainable construction is being highlighted in Korea. In particular, the trend is being discussed about life cycle of the apartment houses in various aspects. However the Korean construction market and housing policy have been increasingly focusing on supplier. Structures become progressively obsolete after a certain period, but their durability can be extended with proper maintenance management. Accordingly, if maintenance management on the structures is made efficiently, waste of construction energy and damage to the environment and economic loss due to early demolition and reconstruction can be effectively prevented. Therefore, this study aims to suggest the user manual design for the efficient maintenance in apartment housing

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.145-146
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• 2023

One of the causes of recent construction site collapses was that the compressive strength of concrete was less than half of the allowable design standard strength range. In the safety diagnosis of structures, the compressive strength of concrete is a factor that determines the durability of a building. Therefore, in this study, we aim to examine the characteristics of compressive strength according to the particle size distribution of coarse aggregate among the compressive strength factors using small-diameter cores. To avoid problems when collecting cores, core specimens with diameters of 100×200, 50×100, and 25×50 (mm) were manufactured directly. As a result of measuring the compressive strength of concrete for each diameter, the larger the core diameter, the higher the compressive strength. has increased.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.651-657
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• 2010

A composite piston with a crown made of steel and a skirt made of NCI is used in a marine diesel engine, which has a maximum firing pressure of over 180 bar and a high thermal load. In the fatigue design of the composite piston, the fatigue is influenced by factors such as the load type, surface roughness, and temperature; further, the distribution ratio of the firing force from the crown to the skirt is important for optimizing the design of the crown and skirt. In this study, the stress gradient method was used to consider the effect of the load type. The temperature field on the piston was predicted by cocktail-shaking cooling analysis, and influence of high temperature on fatigue strength was investigated. The load transfer ratio and contact pressure were optimized by design of the surface shape and accurate tolerance analysis. Finally, the cooling performance and durability design of the composite piston were verified by performing a long-term prototype test.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.4
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• pp.11-19
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• 2015

The important properties of EVA (ethylene vinyl acetate) redispersible polymer was waterproof, densification of internal pore space of concrete and ball bearing and micro filler. Also, the significant role of polypropylene(PP) fiber was crack control and blockade of movement for deterioration factors. The most studies for EVA were limited in the field of mortar and PP fiber reinforced concrete had been studied in the state of being restricted unit water content, rich mix and mixing much of the fiber without considering construction site. Therefore, the control mix design were applied in ready mixed concrete using 10 % fly ash of total cement weight used in batch plant. On the basis of control mix design, EVA contents ranging from 0 % to 10 % of total cement weight and PP fiber contents ranging from 0 % to 0.5 % of EVA concrete volume were used in the mix designs. The results showed the maximum compressive strength value was measured at EVA 5.0 % and PP fiber 0.1 %, the minimum water absorption ratio was at EVA 10 % and PP fiber 0 %, the durability factor for freezing and thawing resistance was at EVA 5.0 % and PP fiber 0.3 % and the minimum weight reduction ratio of resistance to sulfuric acid attack was at EVA 10 % and PP fiber 0.5 % after curing age 42days. Meanwhile, From these results, PP fiber reinforced EVA concrete would be very benefit, if each optimal mix types were used in hydraulic structures, underground utilities and agricultural structures.