• International Journal of Highway Engineering
• /
• v.14 no.6
• /
• pp.1-11
• /
• 2012

PURPOSES : The purpose of the study was to examine dynamic features of concrete after mixing a little macro fiber with small aspect ratio and long length utilized for bridge, tunnel and shotcrete for tensile performance and crack control in domestic/overseas countries with cement concrete pavement mix. METHODS : Coarse aggregates with small aspect ratio and macro fibers with maximum length of approximately 32 mm are introduced in small quantities in the mix proportions of concrete pavement so as to prevent loss of the workability. Then, this study intends to evaluate the applicability of macro fibers in the mix proportions of concrete pavement by examining the basic construction performance, as well as the change of toughness, the equivalent bending strength and the flexural toughness index caused by compression, bending, tension and the flexural stress-displacement curve. RESULTS : As the results, in each kind of macro fiber, polyvinyl alcohol fiber and steel fiber displayed a good performance. CONCLUSIONS : In 0.2 and 0.3% of fiber contents, it is appeared that polyvinyl alcohol fiber has a large effect on improvement of tensile performance and steel fiber on improvement of deforming performance of bending stress.

• Tunnel and Underground Space
• /
• v.27 no.5
• /
• pp.295-302
• /
• 2017

In this study, a new quantitative instrumentation and measurement standards applicable to the field of mining has been proposed to improve the problems of the current measurement practices that apply the measuring standards of the civil engineering field (road, railway, etc.). With the data coordination of the mine reclamation corporation, we collected data on ground subsidence in the abandoned mine area, and studied various techniques for establishing a new management reference value based on the manual measurement data measured in the field. As a result, new instrumentation and measurement standards is set up and proposed by using statistics like the average value, the third quartile, the 95% confidence, and the maximum value.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2001.03a
• /
• pp.81-88
• /
• 2001

Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity is widely used in determination of rock quality in road and railway tunnel design. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test in laboratory, such as uniaxial compressive strength(UCS), p wave velocity, Young's modulus and electrical resistivity. We correlate each test results and we found out that electrical resistivity has exponentially related to UCS and P wave velocity and linearly related to Young's modulus. And we accomplished electrical resistivity survey in field site and carried out electrical resistivity logging at in-situ area. Also we peformed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to rock classification results. We found out that electrical resistivity logging data are highly correlate to RQD, Q and RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RQD, Q and RMR.

• Explosives and Blasting
• /
• v.22 no.3
• /
• pp.97-101
• /
• 2004

The using of Gun powders are getting grower than power due to the road opening, tunnel digging, the highest building, the pound digging on the construction industry, it also happen blasting accident as well, and it become society issue more than more. In this study, The check list far the human cause of the most rate among the blasting accident was developed in availing of accident investigation chart for the analysis of the blasting accident of already developed and FTA technique analysis with the analysis systematically of blasting accident. And then, Analysis for the application was carried out in construction cite, availing of the check list. As results, The most error has broken out at charge work, an uncomfortable processes, among the blasting work. Thus, It is a matter for consideration with improvement work.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.4
• /
• pp.146-154
• /
• 2011

Recently, the paradigm of social infrastructure investment has been changed from new construction to maintenance and management. As a consequence, the management and maintenance system of existing highway facilities needed an innovation involving the concept of asset management. This paper discusses the new facility management system suitable to local highway agencies. The new system incorporates asset management concept so that it can analyze the network level facility management solution and it can also improve the budget efficiency for local government. This paper also presents systematic method to integrate various facilities for management system.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.23 no.4
• /
• pp.428-435
• /
• 2015

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is $3.1-4.2^{\circ}C$ lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2003.06b
• /
• pp.119-137
• /
• 2003

Electrical resistivity is one of physical property of the earth and measured by electrical resistivity survey, electrical resistivity logging and laboratory test. Recently, electrical resistivity Is widely used In determination of rock quality in road and railway tunnel design. To get more reliable rock quality data from electrical resistivity, it needs a lot of test and study on correlation of resistivity and rock quality. Firstly, we did rock property test In laboratory, such as uniaxial compressive strength(UCS), P wave velocity, Young's modulus and electrical resistivity. We correlate each test results and we found out that electrical resistivity has exponentially related to UCS and P wave velocity and linearly related to Young's modulus. And we accomplished electrical resistivity survey in field site and carried out electrical resistivity togging at In-situ area. Also we performed rock classification, such as RQD, RMR and Q-system and we correlate electrical resistivity to rock classification results. We found out that electrical resistivity logging data are highly correlate to RQD, Q and RMR. Also we found out that electrical resistivity survey data are lower than electrical resistivity logging data when there are faults or fractures. And it cause electrical resistivity survey data to lowly correlate to RQD, Q and RMR.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.11a
• /
• pp.485-492
• /
• 2005

Since blast-induced vibration may cause serious problem to the rock mass as well as the nearby structures, the prediction of blast-induced vibration and the stability evaluation must be performed before blasting activities. Dynamic analysis has been Increased recently in order to analyze the effect of the blast-induced vibration. Most of the previous studies, however, were based on the continuum analysis unable to consider rock joints which significantly affect the wave propagation and attenuation characteristics. They also adopted pressure curves estimated by theoretical or empirical equations as input detonation load, thus there were very difficult to reflect the characteristics of propagating media. In this study, therefore, we suggested a discontinuum dynamic analysis technique which uses velocity waveform obtained from a test blast as an input detonation load. A distinct element program, UDEC was used to consider the effect of rock joints. In order to verify the validity of proposed method, the test blast was simulated. The predicted results from the proposed method showed a good agreement with the measured vibration data from the test blast Through the dynamic numerical modelling on the planned road tunnel and slope, we evaluated the effect of blast-induced vibration and the stability of rock slope.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2020.06a
• /
• pp.50-51
• /
• 2020

Recently, construction projects are gradually becoming high-rise and large-scale, and furthermore, the use of new buildings is emerging through the deepening of the underground. In this situation, a lot of fire damage has occurred in recent years, mainly in buildings and tunnel structures. In particular, damages caused by fires during large-scale construction projects such as freezing warehouse accidents are increasing. In this situation, in Korea, it is still trying to secure safety from human fire through the administrative system divided into the building law and the fire law, but it is being developed in a negative direction rather than a positive direction. The fire risk is getting bigger even when the road is not maintained. In this current situation, it is considered that the development of a Korean integrated life safety code centering on the consciousness base of Koreans will be necessary, and in particular, the ease of revision will also be needed by promoting the integrated safety code rather than current laws and regulations. This is a summary of the future tasks.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.22 no.1
• /
• pp.121-133
• /
• 2020

Globally, the frequency and intensity of abnormal climate events are increasing. Since this can directly damage lives and property, it is important to establish and implement an appropriate maintenance strategy in response to abnormal weather. Facilities built in cold regions where cold wave or heavy snow occurs frequently can be more damaged by freeze-thaw than facilities located in other regions. However, there are no clear criteria for quantitatively identifying the damage of freeze-thaw and how to cope with it. Therefore, based on the results of indoor freezing tests, the freezing conditions considering regional climate characteristics were selected as one day at -14℃, two days at -7℃ or three days at -5℃. As a result, it was confirmed that they were in the freeze-thaw environment in order of Daegwallyeing (8.3 times), Cheorwon (5.3 times) and Taebeak (4.9 times) in Gangwon region. Through this study, the evaluation criteria of freeze-thaw of road tunnels were newly proposed. The freeze-thaw evaluation criteria of the road tunnel presented in this study can be used for the quantitative evaluation and maintenance strategy of tunnels in cold regions.