• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.377-386
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• 2012

Crack sealing has been widely used in the pavement maintenance due to its advantage of repairing the cracks at the preliminary stages. However, it has been analyzed that the crack sealing work process is dangerous and labor intensive. Moreover, quality and productivity of crack sealing work are highly depended on labor experience and skills. Therefore, various crack sealing machines have been researched but revealed many limitations in practical application. This research analyses conventional crack sealing work process and previously developed crack sealing machines in order to develop an automated pavement crack sealing machine which can be practically and widely applied in the construction fields. This paper develops the previously proposed conceptual design by drawing detailed designs and fabricating the hardware(manipulator and end-effector) of the automated pavement crack sealing machine. The crack sealing machine suggested in this paper overcomes limitations of existing crack sealing machines and designed to meet the domestic road conditions and regulations. It is expected that automating the conventional crack sealing method contributes to the improvement of quality, economy and reduce accidents.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4D
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• pp.577-584
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• 2011

A series of field and laboratory permeability tests were performed to investigate the pore-clogging phenomenon of porous concrete used for pavement materials of a road. The field permeability tests were conducted for 37 study points in Jeju city, using the porous concretes with 13mm of maximum coarse aggregate ($G_{max}$). The results show that the service life of porous concrete is about 22 months when the permeability of the porous concrete is designed for 0.01 cm/sec. Some specimens were made with the purpose of recreating pore-clogging phenomenon. Tests were done for injected concentration of pore-clogging materials or size of maximum coarse aggregates ($G_{max}$). The test results demonstrated that relatively long in service life experienced with small amount of injected concentration of pore-clogging materials, whereas relatively short in service life experienced with a reduction in size of maximum coarse aggregates ($G_{max}$). In conclusion, the service life of porous concrete is in proportion to the concentration of pore-clogging material but it is in inverse proportion to the size of maximum coarse aggregate ($G_{max}$). Thus, the persisting period of porous concrete can be determined with respect to concentration of pore-clogging materials or size of maximum coarse aggregates ($G_{max}$).

• Journal of the Korean Geotechnical Society
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• v.30 no.1
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• pp.65-74
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• 2014

Cemented soils have been widely used in road and dam construction, and recently ground improvement of soft soils. The strength of such cemented soils can be tested by using cored sample or laboratory-prepared specimen through unconfined compression or triaxial tests. It takes time to core a sample or prepare a testing specimen in the laboratory. In a certain situation, it is necessary to determine the in-situ strength of cemented soils very quickly and on time. In this study, the relation between unconfined compressive strength and shear wave velocity was investigated for predicting the in-situ strength of cemented soils. A small cemented specimen with 5 cm in diameter and 10 cm in height was prepared by Nakdong river sand and ordinary Portland cement. Its cement ratios were 4, 8, 12, and 16% and air cured for 7, 14, and 28 days. For recycling of resources, a blast furnace slag was also used with sodium hydroxide as an alkaline activator. The shear wave velocity for cemented soils was measured and then unconfined compressive strength test was carried out. As a cement ratio increased, the shear wave velocity and unconfined compressive strength increased due to increased density and denser structure. The relation between unconfined compressive strength and shear wave velocity increased nonlinearly for cemented soils with less than 16% of cement ratio.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.2 s.5
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• pp.129-140
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• 2004

In this paper, we conduct the research about optimal aggregation interval of travel time data on interrupted traffic flow and verify the reliability of AVI collected data by using car plate matching method in RTMS for systematic collection and analysis of link travel time data on interrupted traffic flow rural arterial. We perform Kolmosorov-Smirnov test on AVT collected sample data and on entire population data, and conclude that the sample data does not represent pure random sampling and hence includes sample collection error. We suggest that additional review is necessary to investigate the effectiveness of AVI collected sample data as link representative data. We also develop statistical model by applying two estimation techniques namely point estimation and interval estimation for calculating optimal aggregation interval. We have implemented our model and determine that point estimate is preferable over interval estimate for exactly selecting and deciding optimal aggregation interval. Our final conclusion is that 5-minute aggregation interval is optimal to estimate travel time in RTMS, as is currently being used our investigation is based on AVI data collected from Yang-ji to Yong-in $42^{nd}$ National road.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.97-103
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• 2020

The newly improved multistep steel pipe grouting method was applied to an existing steel pipe-reinforced grouting method. It was applied in order to prevent a damage caused by ground failure from excessive grouting pressure in a tunnel construction. The tunnel goes under a highway and a ramp connected to a rest area on OO highway with 11.3~12.1 m depth cover and is a part of roadbed facility construction section ordered by OO public corporation. The improved grouting method provides pre-construction work condition assessment technique through new water injection limit test and grouting effect assessment technique by grouting type assessment. It also includes assessments on interval of joints, appropriate grouting pressure, and optimal operation time to be applied to current operations. Application of the grouting method allowed the smooth road management in shallow-depth grouting construction area located upper part of tunnel excavation. Moreover, the possibility of the application of the method not only to shallow-depth grouting construction but also to various steel pipe-reinforced grouting constructions was confirmed.

• Journal of Korean Society of Transportation
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• v.33 no.3
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• pp.315-321
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• 2015

ATMS calculates section travel time using two-way communication system called DSRC(Dedicated Short Range Communications) which collects data of RSE (Road Side Equipment) and Hi-pass OBU (On-board Unit). Travel time estimation in urban area involves uncertainty due to the interrupted flow. This study not only analyzed real-time data but also considered pattern data. Baek-Je-Ro street in Jeon-Ju city was selected as a test site. Existing algorithm was utilized for data filtering and pattern data building. Analysis results repoted that travel time estimation with 20% of real-time data and 80% of pattern data mixture gave minimum average difference of 37.5 seconds compare to the real travel time at the 5% significant level. Results of this study recommend usage of intermixture between real time data and pattern data to minimize error for travel time estimation in urban area.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.27-35
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• 2009

This study was conducted to suggest resonable quality measurement methods of asphalt pavements to be used in the Pay adjustment. The Pay adjustment is a method to adjust the construction cost according to the pavement quality based on the statistic theories. Many U.S states use Pay adjustment and the PWL(Percent with in Limit) is calculated using their quality index tables. In this study, the application of PWL in Korea was evaluated by comparing the PWL South Carolina with the probability theories. The probability values and the PWL obtained using the data collected from the test roads were used to determine the pay factors suggested by AASHTO and the pay factors between them were closed to each other. In addition, the PWL was very similar to the probability obtained using the predicted average of the population when calculating the Z-values. The pay factors were obtained using artificial data whose average satisfied the codes and whose standard deviation was large. The pay factors were less than 100% in the quality measurements can be performed using the PWL methods, and with the development of the korea quality index table, the PWL methods can be applied in korea.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.69-77
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• 2000

In this paper, the effects of the positions of the potential and current probes on the measurements of the ground resistance and potential gradients with the fall-of-potential method are described and the testing techniques to minimize the measuring errors are proposed. The fall-of-potential method is theoretically based on the potential and current measuring principle and the measuring error is primarily caused by the position and ground resistance of the measuring probes. The ground resistance is calculated by applying the 61.8% and rule in the fall-of-potential method, and then the potential probe is located on the straight line between the grounding electrode to be measured and the current probe. However, sometimes the grounding electrode to be measured and the measuring probes in on-site test might not be arranged on the straight line with adequate distance because there are building, road block, construction and other establishments. Provided that the grounding electrode to be measured and the measuring probes ar out of position on the straight line or have inadequate distance, the measurement of the ground resistance classically falls into an error and the measured ground resistance should be corrected. Measurements were focused on the grounding electrode system made by the ground rods of 2.4m long. It was found that the suitable separation between the grounding electrode to be measured and the current probe is more than 5 times of the length of the grounding electrode to be measured.

• Journal of Life Science
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• v.16 no.2 s.75
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• pp.266-273
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• 2006

This study is investigated the effect of selenium against neurotoxicity induced by MPTP(1-methy-4-phenyl-propion-oxypiperidine) in mice. In order to demonstrate neuroprotective activity of selenium, mice were administrated orally with selenium(25, 50, 100 ${\mu}g/kg$, once/day) for 10 days, and MPTP(10 mg/kg) was injected subcutaneously into the mice for 6 days from the beginning 1hr before selenium treatment. Test of rota road activity was inhibited by treatment with selenium in MPTP-induced neurotoxicity group when compared to MPTP treatment group in normal mice. Monoamine oxidase(MAO)-B activity and cerebral lipid peroxide content were significantly decreased in the treatment of selenium in MPTP-induced neurotoxicity group when compared to MPTP treatment group in normal mice and MAO-A was not affected. Activities of cerebral superoxide dismutase, catalase and glutathione peroxidase were significantly increased in the treatment of selenium in MPTP-induced neurotoxicity group when compared to MPTP treatment group in normal mice. These results suggest that selenium might be estimated the result from the cooperative action of its inhibitory effect on monoamine oxidase-B with that of the enhancement of antioxidant(SOD, catalase, GSH-Px) defence ability.

• Korean journal of communication and information
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• v.62
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• pp.244-263
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• 2013

There have been enormous social impacts on many areas, including science journalism, since the so-called "Hwang Woo Suk" incident. Although wide demand for better science journalism has been aroused since then, but it is hard to find an evidence to prove we have reached the point. This study examines how major Korean newspapers report Unidentified Flying Objects in order to test if the level of science journalism had been elevated. As results, still it is a long road ahead to achieve the goals because most reports were taken from the international news agents or from the witnesses rather than scientific researches and analyses; terminologies used in the stories were ambiguous; follow-up stories were rare, the sources were usually pseudo-scientific, wanton errors in basic facts and coherence, and other problems were found. It could be suggested that the dependency on supplied news to be reduced, journalists who understand both science and journalism are required, inner regulations on science reporting to be established, correct quotations and fact-checks to be accomplished, fairness to be maintained within the boundary of normal science.