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Kim D.H.,Kunsan National University | Lee S.G.,Kunsan National University | Lee I.K.,Korea Expressway Corporation Research Institute
Renewable Energy | Year: 2014

Considering nonlinear soil-pile interaction, seismic fragility analysis of offshore wind turbine was performed. Interface between ground soils and piles were modeled as nonlinear spring elements. Ground excitation time histories were applied to spring boundaries. Two methods of applying ground motion were compared. Different time histories from free field analysis were applied to each boundary in the first loading plan (A). They were compared with the second loading plan (B) in which the same ground motion is applied to all boundaries. Critical displacement for wind turbine was proposed by using push-over analysis. Both the stress based and the displacement based fragility curves were obtained using dynamic responses for different peak ground accelerations (PGAs). In numerical example, it was shown that seismic responses from loading plan A are bigger than from plan B. It seems that the bigger ground motion at surface can cause less response at wind turbine due to phase difference between ground motions at various soil layers. Finally, it can be concluded that layer by layer ground motions from free field analysis should be used in seismic design of offshore wind turbine. © 2013 Elsevier Ltd.

Choi Y.-H.,Korea Expressway Corporation Research Institute | Chung Y.,Korea Transport Institute
19th Intelligent Transport Systems World Congress, ITS 2012 | Year: 2012

Electronic toll collection systems (ETCS) have begun to be introduced globally in the early 1990s in order to relieve traffic congestion at expressway toll gates and are currently operate in approximately 30 countries. However, studies related to safe operation of ETCSs are insufficient. Since ETCS tag-equipped vehicles pass toll gates without any stop while general vehicles stop to pay tolls, speed differences between high speed and low speed vehicles occur at toll gates. Therefore, when ETCSs are introduced, guidelines for toll gate lane operation are necessary. In this study, we identify the necessity of ETCS operation guidelines through analyses of cases of ETCS operation in various countries and identify the risk of the occurrence of accidents based on speed differences between ETCS tag-equipped vehicles and general vehicles by examining actual running speeds of actual vehicles. We also identify that by allowing vehicles that have entered the wrong lane to change lanes reduces the risk of accidents and prevents accidents resulting from speed differences between ETCS tagequipped vehicles and general vehicles. In particular, we investigated the relationship between speed differences and accident rates to establish traffic operational guidelines in relation to speed differences.

Lin W.,Shanghai Maritime University | Park D.-G.,Pavement Research Center | Ryu S.W.,Korea Expressway Corporation Research Institute | Lee B.-T.,Chung - Ang University | Cho Y.-H.,Chung - Ang University
Construction and Building Materials | Year: 2016

Pervious pavement has been used widely due to efficient hydrological characteristics such as reduction of runoff during floods, providing delay of rainwater into sewer systems and ground water quality improvement. However, clogging prevents it from functioning properly due to sedimentation after a short period of service, which results to poor permeability and performance of pervious pavement. In this study, the causes of clogging were investigated and a clogging simulator was developed in order to evaluate the sustainable permeability of porous concrete block pavement in advance. Furthermore, a test method for verifying the sustainability of infiltration which can predict and assess the permeability performance by years of service was proposed. In addition, the penetration of contaminants also varies depending on vehicle vibration and the rainwater that permeates together with it. It was found that the pores were easily clogged with the vibration frequency increased, but with the amount of contaminants increased to a degree clogging had less influence on vibration. When various types of porous concrete block pavers were evaluated with the proposed sustainable permeability test method, the coefficient of permeability before and after the test have shown very high correlation. © 2016 Published by Elsevier Ltd.

Lin W.,Shanghai Maritime University | Ryu S.,Korea Expressway Corporation Research Institute | Hao H.,Shanghai Maritime University | Cho Y.-H.,Chung - Ang University
Construction and Building Materials | Year: 2016

Few studies have been conducted on horizontal shifting prediction models that consider block shapes and laying patterns for block pavements. To develop a prediction model, a combination of different block shapes and laying patterns was evaluated by computer modeling and laboratory tests. The relationship between the force and displacement was recorded via a photogrammetric method using a friction tester. In order to quantify the recorded video results, rigid body analysis was performed. The results of laboratory experiments and the rigid body analysis offered a good match. A displacement vector was used to express the movement of the block with time, according to the start and end position information of each block. Also, a concept of Specific D-Moment (SDM) was proposed to describe the relationship between the movement of the individual blocks and the entire movement. A horizontal shifting mechanistic-empirical prediction model of concrete block pavement is proposed based on regression analysis of the existing performance data. According to the prediction model, higher SDM values give lower cumulative amounts of horizontal shifting due to traffic. © 2016 Published by Elsevier Ltd.

Kim H.-J.,Korea Expressway Corporation Research Institute | Kim Y.,Cooperation Technology | Sim J.,Hanyang University
KSCE Journal of Civil Engineering | Year: 2015

This study was conducted to assess the field applicability of the Glass Fiber Reinforced Polymer (GFRP) slip-form proposed in previous studies by testing its performance-related properties in various experiments. We compared the initial curing temperature of concrete, which exerts the greatest impact on reducing the construction duration in the slip-form system, with that when using a steel slip-form. We measured the friction force to compare the cross section formability of the two methods. We then conducted a mock-up test on the basis of the experimental results and assessed its usability and field applicability. The GFRP form maintained a higher curing temperature than the steel form, and the difference in the curing temperature was larger with an increase in the air temperature and smaller with a decrease in the air temperature. The slip-up rate in the slip-forming was confirmed to be affected the most by the initial curing temperature of the concrete, whereas the cross-section formability was affected by the friction force and adhesion of the concrete. The results of the experiments verified that the GFRP slip-form efficiently overcomes the drawback of the steel slip-form system and maximizes the advantages of slip-forming. © 2015 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg

Kim H.-J.,Korea Expressway Corporation Research Institute | Sim J.,Hanyang University
KSCE Journal of Civil Engineering | Year: 2015

In this paper, a more effective construction method is introduced, wherein the mechanical advantages of Glass Fiber Reinforced Polymer (GFRP) are applied to the slip-form method. The slip-form method, which is a typical moving form method, has advantages such as reduced construction duration and simple components because it enables continuous forming work of concrete in a single construction. However, it is vulnerable to corrosion, quality control is difficult, and the form plate cannot be reused. In this study, a tensile test was carried out on a GFRP plate by using a new method to apply the steel form to the GFRP plate. Effective GFRP slip-form shape and the application method were proposed by conducting finite element analysis and parametric analysis based on the results of the GFRP plate tensile test; performance was verified through a structural test. From the test results, the GFRP slip-form showed better structural performance than the steel form, and the GFRP slip-form construction method may reduce costs because of its reusability, easy quality control, and reduced construction duration. © 2015 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg

Gil H.,Korea Expressway Corporation Research Institute | Kang S.,Korea Expressway Corporation Research Institute
Advances in Structural Engineering | Year: 2015

The simultaneous presence of multiple heavy trucks on road bridges causes a higher stress to the structural members of bridges than the presence of a single heavy truck. Truck traffic data acquired using weigh-in-motion systems are typically used to assess the multiple-presence probability for side-by-side and following trucks. A number of high-speed weigh-in-motion (HS-WIM) systems are installed in the Korean Expressway Network to control overloaded vehicles and obtain long-term truck weight data. In this study, the multiple-presence probabilities for following and side-by-side trucks were determined using data from two HS-WIM sites. The correlation probability between the gross vehicle weights (GVWs) of successive trucks was also calculated. To determine the characteristics of heavier truck loads, the multiple-presence probabilities for the overweight trucks, which exceed the legal weight limit, were calculated separately. The analysis of the HS-WIM data showed that the multiple-presence probabilities of the trucks increased with the headway distance of following or side-by-side trucks, and the probability of following truck events was lower than that of side-by-side truck events. The probability of side-by-side truck events increased with the increase of daily truck traffic (DTT), whereas the probability of following truck events was only slightly affected by the DTT. The full correlation probabilities of the GVW for the following and side-by-side trucks were low.

Park J.,Korea University | Lee K.-H.,Korea Expressway Corporation Research Institute | Choi H.,Korea University | Lee I.-M.,Korea University
Tunnelling and Underground Space Technology | Year: 2016

This study applies the harmony search (HS) inverse analysis algorithm and develops the tunnel resistivity prediction (TRP) system for predicting the location, thickness, permittivity ratio, and conductivity of the anomalous zone ahead of the tunnel face by utilizing electrical resistivity. The relationship between the four characteristic values of the anomalous zone and the electrical resistance is derived using Gauss’ laws and Ohm's laws. The optimum values of HS algorithm operators (such as the harmony memory considering rate (HMCR) and the pitch adjust rate (PAR)) are proposed that can provide the best inverse analysis that correlates the four characteristic values with the electrical resistance. Also, the prediction accuracy of inverse analysis using the proposed HS algorithm is verified by laboratory tests on the artificially formed ground with an anomaly. An electrical resistance measuring system is devised to obtain the electrical resistance of the ground, and inverse analyses are performed from the measured resistance to estimate the four characteristic values of the artificial anomaly. The test results from laboratory scale experiments show that the characteristics of the anomalies are predicted reasonably well, resulting in less than 3% average error. This paper is part 1 of the companion papers; the second paper will verify the developed system through the field tests. © 2016 Elsevier Ltd

Lin W.,Chung - Ang University | Ryu S.,Korea Expressway Corporation Research Institute | Cho Y.-H.,Chung - Ang University
Journal of Performance of Constructed Facilities | Year: 2016

As industrialization advances, the increase in impermeable areas in urban regions has changed the water circulation system. Hence, many environmental issues such as heat islands and city floods have arisen. To solve this issue, related research with a high budget allocation is currently being carried out. A method of addressing this issue is to utilize permeable block pavements. The bearing capacity and hydrological efficiency of permeable block pavement with different base types was evaluated in this study using two accelerated pavement testings (APTs). Rutting was evaluated by performing a comparative analysis in each permeable block pavement. Furthermore, the hydrological characteristics were reviewed through a rainfall simulation experiment. The results of APT show that performance of permeable block pavements varies depending on the base type and traffic volume. Based on the result, it was demonstrated that the permeable block pavement is applicable for a vehicle road as well as the sidewalk. In addition, it was demonstrated that this pavement can improve the water circulation system. © 2014 American Society of Civil Engineers.

Oh H.J.,Kyung Hee University | Oh H.J.,Korea Expressway Corporation Research Institute | Cho Y.K.,Kyung Hee University | Seo Y.,Kennesaw State University | Kim S.-M.,Kyung Hee University
Construction and Building Materials | Year: 2016

The objective of this study is to understand the confining effect of two base types on the longitudinal displacements of the continuously reinforced concrete pavement (CRCP) subjected to short- and long-term temperature loadings. To this end, a series of full field experiments was carried out at two highway CRCP sections in Korea: one section with asphalt bond breaker beneath the concrete slab and the other with lean concrete beneath the concrete slab. Each section was instrumented with linear variable differential transformers and thermocouples to monitor the longitudinal displacements (expansions and contractions) of the concrete slab at different longitudinal locations as the temperature changed throughout the year. Results showed that the lean concrete base was more effective at confining the daily maximum expansions than the asphalt bond breaker especially in the region between the free end and 10 m away from the free end. In addition, the free-end expansion gradients (expansion per unit temperature change) were developed based on the test data to estimate the annual maximum expansions along with the daily maximum expansions of the terminals. Finally, the optimum expansion joint widths were proposed for CRCP with varying construction and design conditions, such as base type, slab length, and construction season. © 2016 Elsevier Ltd. All rights reserved.

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