• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.507-510
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• 2005

In winter, a large amount of de-icing salts such as $CaCl_2$, NaCl have been used on highways for road safety. They make concrete structures deteriorated. In this study, the chloride diffusion of concrete in presence of de-icing salt was investigated. The diffusion coefficient of chloride in presence of $CaCl_2$ solution was larger than in presence of NaCl solution. Therefore, it is necessary to assess chloride profile in presence of $CaCl_2$ by different way from the case in presence of NaCl solution or seawater.

• 한국도로학회:학술대회논문집
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• 2010.09a
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• pp.447-454
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• 2010

• 한국도로학회:학술대회논문집
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• 2010.09a
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• pp.365-370
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• 2010

• 한국도로학회:학술대회논문집
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• 2010.09a
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• pp.421-426
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• 2010

• International Journal of Highway Engineering
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• v.8 no.4 s.30
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• pp.25-36
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• 2006

Through field surveys and evaluation on several widened concrete pavements, issues on construction and design related problems are broken down into three categories to be discussed; poor smoothness, influence of traffic vibration on concrete curing, and poor connection to the existing pavement. There are many places where about 100mm only of the marginal strip is removed and where defects such as widening and faulting are observed. Also cracks arise again from the patched areas due to stress concentration near the joint. Roughness on the widened concrete pavement was evaluated and there are some stations where the smoothness limit is over passed. For design consideration, shortage of the required force in the tie-bar is expected in case of road widening specially from 3 lanes to 4 lanes. Finally the average pull-out force of specimens made from the current practice was about 57% of the required force. New connecting methods were suggested in this study.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.67-74
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• 2012

PURPOSES: In this study the influence factors related to abrasion resistance of interlocking concrete block have been evaluated, and comparisons between various domestic and foreign abrasion test methods was also accomplished. METHODS: The modified rotational cutting method suggested in ASTM C 944 was applied. Surface materials with different types of fine aggregate such as crushed sand, sea sand, and mixture of crushed and sea sand were tested to compare the aggregate effect for abrasion resistance. RESULTS: The different surface mixtures with various W/C ratios, mortar and fly ash ratios have been investigated for functional and economical considerations. CONCLUSIONS: This study had obtained reliable results by changing diamond blade of rotating cutter. Therefore, in order to improve the abrasion resistance of interlocking concrete block for road, a new mix design was proposed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.2 no.1
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• pp.121-128
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• 1998

The rail, which supports the train road, distributes the wheel loads to the tie by rail stiffness. Subway sleeper on concrete ballast is construction of PC or RC sleeper. The present, PC sleeper is constructed of line 1, 2, 3, 4 Seoul Subway and RC sleeper is planing construction for the STEDEF system on concrete ballast of the line 5, Seoul, Taegu, and Kwangju Subway. The major purpose of this study is to check influence of the angle with analysising the behavior of sleeper according to the existent or non-existent of angle. And the study is carried to check static analysis by manufacture of same model.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.1
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• pp.35-40
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• 2004

This study is performed to examine the physical and mechanical properties of eco-concrete using soil, natural coarse aggregate, excellent soil compound and polypropylene fiber. The test result shows that mass loss ratio is decreased with increasing the content of coarse aggregate and excellent soil compound. The compressive and flexural strengths are increased with increasing the content of coarse aggregate, excellent soil compound and polypropylene fiber. The coefficient of permeability is decreased with increasing the content of coarse aggregate and excellent soil compound, but it is increased in 0.2% polypropylene fiber content. The lowest coefficient of permeability is showed in $5.066\times 10^{-9}$cm/s. These eco-concrete can be used for farm road.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.21-29
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• 2012

PURPOSES: This study is to investigate the mechanical performance of the fiber reinforced lean concrete with respect to different types of fibers. METHODS: Increased vehicle weight and other causes from the exposed conditions have accelerated the deteriorations of road pavement. A new multi-functional composite pavement system is being developed recently in order to extend service life and upgrade the pavement. A variety of tests were conducted before and after hardening of the concrete. RESULTS: From the test results, it was found that the use of different types of fibers did not affect the compressive strength development. This might be due to the inherent property of the lean concrete. When steel fibers were used relatively greater flexural strength and flexural fracture toughness were developed. Also addition of fly ash by replacing a part of Portland cement the fracture toughness was slightly increased. CONCLUSIONS: It has been known that the addition of fibers and use of mineral admixture can be positively considered in the development of multi-functional composite pavement system as its required mechanical performance is obtained.

• Journal of Biosystems Engineering
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• v.33 no.1
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• pp.38-44
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• 2008

The freight vehicle is mostly used to transport the fruit. Shock and impact generated by the freight vehicle may give serious damage to fruits hence to reduce the fruits damage, the optimum packaging design during transportation by vehicle is required. In order to design the packaging system for fruit transportation optimally, the comprehension of characteristic for vibration and shock acting on vehicles under various road conditions and loading methods is required. This research was performed to analyze the shock characteristics, acceleration level and power spectral density (PSD) of the fruit transportation vehicles under several travel roads and positions. The vibration signal was measured and analyzed at the transportation vehicle operating on the road of three different surface conditions. The maximum acceleration was measured at the rear-end of the vehicle, and the acceleration in the direction of up-and-down (z-axis) was much greater than those in the directions of back-and-forth (x-axis) or right-and-left (y-axis). The peak acceleration in the direction of up-and-down (z-axis) at the vehicle driving on the expressway, the local road paved with concrete, and unpaved local road were 5.3621 G, 8.232 G, and 14.162 G respectively. PSD at 2.44 Hz showed maximum value at all road conditions. The maximum values of PSD on the expressway, a local road paved with concrete, and unpaved local road were 0.0075222 $G^2/Hz$, 0.058655 $G^2/Hz$, and 0.24598 $G^2/Hz$ respectively. The value of PSD decreased with an increase of the vibration frequency of the transportation vehicle. In most cases, the vibration frequency was below 20 Hz during transportation.