• Economic and Environmental Geology
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• v.23 no.2
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• pp.215-219
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• 1990

Geological and electrical resistivity surveys along the survey line of about 3 km between Kyungsangbukdo Youngilgun Hodong and Gwangmyungdong using by dipole-dipole electrode array method were carried out to examine the boundary and structural relationship between Tertiary Pohang and Janggi basins. Electrical resistivity data were interpreted qualitatively and quantitatively by means of pseudosection of apparent electrical resitivity distribution and finite difference method for two dimensional geologic structure model. The nearly vertical fault zone with low electrical resistivity value of 1-5 Ohm-m and widths of about 200m at the surface and 400 m at depth exists around 1.2 km west of national road between Ocheoneup and Yangbukmyun. Mudrocks, sandstones and tuffaceous rocks are widely distributed with electrical resistivity values of 6-77 Ohm-m. Especially, tuffaceous rocks with relatively high electrical resistivity value are predominant at eastern side of fault zone. Consequently, it is known that Pohang and Janggi basins are in fault contact.

• Structural Engineering and Mechanics
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• v.49 no.2
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• pp.203-223
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• 2014

The extensive use of prestressed reinforced concrete (PSC) highway bridges in marine environment drastically increases the sensitivity to both fatigue-and corrosion-induced damage of their critical structural components during their service lives. Within this scenario, an integrated method that is capable of evaluating the fatigue reliability, identifying a condition-based maintenance, and predicting the remaining service life of its critical components is therefore needed. To accomplish this goal, a procedure for fatigue reliability prediction of PSC highway bridges is proposed in the present study. Vehicle-bridge coupling vibration analysis is performed for obtaining the equivalent moment ranges of critical section of bridges under typical fatigue truck models. Three-dimensional nonlinear mathematical models of fatigue trucks are simplified as an eleven-degree-of-freedom system. Road surface roughness is simulated as zero-mean stationary Gaussian random processes using the trigonometric series method. The time-dependent stress-concentration factors of reinforcing bars and prestressing tendons are accounted for more accurate stress ranges determination. The limit state functions are constructed according to the Miner's linear damage rule, the time-dependent S-N curves of prestressing tendons and the site-specific stress cycle prediction. The effectiveness of the methodology framework is demonstrated to a T-type simple supported multi-girder bridge for fatigue reliability evaluation.

• ETRI Journal
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• v.38 no.4
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• pp.787-797
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• 2016

Mining, construction, and other special vehicles for heavy use are designed to work under high-performance and off-road working conditions. The driving and executive mechanisms of the support structures and superstructures of these vehicles frequently operate under high loads. Such high loads place the equipment under constant risk of an accident and can jeopardize the dynamic stability of the machinery. An experimental investigation was conducted on a refuse collection vehicle. The aim of this research was to determine the working conditions of a real vehicle: the kinematics of the waste container, that is, a hydraulic rotate drum for waste collection; the dynamics of the load manipulator (superstructure); the vibrations of the vehicle mass; and the strain (stress) of the elements responsible for the supporting structure. For an examination of the force (weight) on the rear axle of a heavy vehicle, caused by its own weight and additional load, a universal measurement system is proposed. As a result of this investigation, we propose an alternative system for continuous vehicle weighing during waste collection while in motion, that is, an on-board weighing system, and provide suggestions for measuring equipment designs.

• Journal of Industrial Technology
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• v.20 no.A
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• pp.149-158
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• 2000

After measuring actual stress by two measurements(Dynamic Strain Meter, Histogram Recorder) on truss rail road bridge, we could perform time history analysis by 3-D beam element method on modelling bridge. And then, after analyzing bridge structure in static by 3-D modelling, we estimated degree of fatigue damage in main member, secondary member of tie zone, cutting area of base metal cross section for confirming the result. In case that the simulated stress is carried out on modeling bridge, most of those simulation mainly is performed by main members. But in real bridge fatigue damage problems generally caused by junctions, connections, joints in which especially local stress is activated. Therefore, in this paper actual stress on critical area was estimated through the analysis result by simulation. With this study, we can estimate the degree of fatigue damage from a safety point of view and comparative accuracy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.67-73
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• 2017

The concrete pavement slabs that suffer expansion due to the Alkali-Aggregate Reaction(AAR) increase and the increase consequently causes unexpected displacement of bridge abutment. As the expansion due to the AAR is greater than that due to the temperature change, lethal load can act on bridge abutment. Therefore appropriate preventive measures may be necessary. The degree of expansion by AAR depends on the severity of AAR and geometry condition of concrete pavement and road structure. In order to prevent damage to bridge, it is effective to release the expansion force of the concrete. It would be advantageous to replace the concrete pavement with asphalt for a long section of concrete pavement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.2963-2978
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• 2017

The Top-K query is currently played a key role in a wide range of road network, decision making and quantitative financial research. In this paper, a Top-K recommendation algorithm is proposed to solve the cold-start problem and a tag generating method is put forward to enhance the semantic understanding of the OLAP session. In addition, a recommendation system for OLAP sessions called "OLAP4R" is designed using collaborative filtering technique aiming at guiding the user to find the ultimate goals by interactive queries. OLAP4R utilizes a mixed system architecture consisting of multiple functional modules, which have a high extension capability to support additional functions. This system structure allows the user to configure multi-dimensional hierarchies and desirable measures to analyze the specific requirement and gives recommendations with forthright responses. Experimental results show that our method has raised 20% recall of the recommendations comparing the traditional collaborative filtering and a visualization tag of the recommended sessions will be provided with modified changes for the user to understand.

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.33-40
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• 2015

PURPOSES: Evaluation of the wind speed effect on the temperature drop of an asphalt mixture during construction, by using the transient heat transfer theory and dominant convective heat transfer coefficient model. METHODS: Finite difference method (FDM) is used to solve the transient heat transfer difference equation numerically for various wind speeds and initial temperature conditions. The Blasius convective heat transfer coefficient model is adapted to account for the effect of wind speed in the temperature predictions of the asphalt mixture, and the Beaufort number is used to select a reasonable wind speed for the analysis. As a function of time and depth, the temperature of the pavement structure is predicted and analyzed for the given initial conditions. RESULTS : The effect of wind speed on the temperature drop of asphalt mixture is found to be significant. It seems that wind speed is another parameter to be accounted for in the construction specifications for obtaining a better quality of the asphalt mixture. CONCLUSIONS: It is concluded that wind speed has a significant effect on the temperature drop of the asphalt layer. Although additional field observations have to be made to reflect the effect of wind speed on the construction specifications, it appears that wind speed is a dominant variable to be considered, in addition to the atmospheric temperature.

• Computers and Concrete
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• v.14 no.6
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• pp.727-743
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• 2014

The management of existing concrete bridges has become a major social concern in many developed countries due to the large number of bridges exhibiting signs of significant deterioration. This problem has increased the demand for effective maintenance and renewal planning. In order to implement an appropriate management procedure for a structure, a wide array of corrective strategies must be evaluated with respect to not only the condition state of each defect but also safety, economy and sustainability. This paper describes a new performance evaluation system for existing concrete bridges. The system evaluates performance based on load carrying capability and durability from the results of a visual inspection and specification data, and describes the necessity of maintenance. It categorizes all girders and slabs as either unsafe, severe deterioration, moderate deterioration, mild deterioration, or safe. The technique employs an expert system with an appropriate knowledge base in the evaluation. A characteristic feature of the system is the use of neural networks to evaluate the performance and facilitate refinement of the knowledge base. The neural network proposed in the present study has the capability to prevent an inference process and knowledge base from becoming a black box. It is very important that the system is capable of detailing how the performance is calculated since the road network represents a huge investment. The effectiveness of the neural network and machine learning method is verified by comparing diagnostic results by bridge experts.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1395-1404
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• 2015

This paper provides information for quantitative evaluation of transportation technology, technology development, and transportation R&D and construction engineering policy agenda. Technology classification structure and key words were established and survey was performed to identify key words of technology for transportation. Then, competitiveness of patents and journal articles is evaluated for Korea, USA, Japan, Germany, France, and England. As a result, USA is the most competitive country for all technology categories based on patents and journal articles. Korea is grouped in upper-middle class for overall transportation technology level. However, there are some variances among the level of technologies. The results of this research can be utilized to establish a road map for transportation R&D and plans.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.3
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• pp.219-228
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• 2001

The research into the field of managing urban utility information (such as gas pipes, power line, telecommunication utilities) is growing ever more important as the efficient management of social infra-structure gets higher and also with the fast technological progress made in nationwide scale of geo-spatial information systems. This research is focused on the collection of street utilities information in urban areas using aerial ortho-images. Until now this has been carried out by on site investigation and ground surveying methods. The result of this research shows that the geometric accuracy was obtainable within 12 cm referenced to 1/1,000 digital map. It was also possible to collect the street utilities which were described in the digital map as well as other information which were not.