Geotechnical Engineering Research Institute

Goyang, South Korea

Geotechnical Engineering Research Institute

Goyang, South Korea
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Lee C.,Geotechnical Engineering Research Institute | Zhuang L.,Geotechnical Engineering Research Institute | Lee D.,Korea University | Lee S.,Korea University | And 2 more authors.
Geothermics | Year: 2017

The effective thermal conductivity of granular materials is widely used in numerous geothermal engineering applications, such as the ground source heat pump (GSHP) system. However, for unsaturated granular materials, it is difficult to predict the thermal conductivity because of the interaction between solid and fluid in media. In this study, the effective thermal conductivity of unsaturated granular materials was measured, reviewed and analysed using a macroscopic pore structure network model with a randomly packed particles. The network model was verified by measured data (soil water characteristics curve, thermal conductivity and etc.) of three different glass beads and also Jumunjin sand (standard sand of South Korea). Upon the series of laboratory experiments, some modification to the existing network model were introduced, such as the use of soil water characteristic curve (SWCC) applied to modelling the thermal conductivity of granular materials. In addition, an empirical correlation between the fraction of the mean radius (χ) and the thermal conductivity at a given saturated condition was developed through comparison with the test results. In the range of lower degree of saturation (5%–20%), the modified network model shows relatively higher thermal conductivity than the laboratory measurements. However, for the higher degree of saturation (>40%), it shows a similar tendency to the laboratory measurements. © 2017 Elsevier Ltd

Park E.,Hanyang University | Kim S.,ICT Convergence and Integration Research Institute | Kim Y.,Geotechnical Engineering Research Institute | Kwon S.J.,Dongguk University
Universal Access in the Information Society | Year: 2017

This study investigated the core motivations for adopting smart home services and explored the approaches and processes through which the motivations were incorporated with the original technology acceptance model (TAM) and the acceptance of the services. To achieve this purpose, an Internet survey was conducted in South Korea. The data (N = 799) from the survey were analyzed using structural equation modeling and confirmatory factor analysis. The results suggested that the perceived compatibility, connectedness, control, system reliability, and enjoyment of smart home services were positively related to the users’ intention to use the services, whereas there was a negative association between the perceived cost and usage intention. The structural results also provided evidence of the validity of the original TAM. Although smart home services have attracted users’ interest in the housing context, only a few studies have examined how the users’ intention to use the services is motivated. The present study represents an initial step to explore the process of adopting smart home services with potential future research areas. © 2017 Springer-Verlag Berlin Heidelberg

Lee J.-H.,Geotechnical Engineering Research Institute | Cho J.W.,Geotechnical Engineering Research Institute | Do J.,North Carolina State University | Park B.,BKGNC Inc.
Key Engineering Materials | Year: 2017

In case of underground construction affected by groundwater, CIP (Cast-In-Place Pile) method is generally used to solve the geo-hydraulic problem. However, as this method has poor connectivity between piles, an auxiliary method for cut-off is required in many cases. In this study, a newly-developed cut-off wall (H-CIP) with no auxiliary method, by using surfactant grout (Hi-FA), which improves anti-washout and infiltration ability, is introduced, and the field applicability of H-CIP method is evaluated. CIP and H-CIP piles were installed with same ground conditions, and field and laboratory tests were conducted to verify the performance, respectively. As results, newly-contrived H-CIP method shows higher field performance for cut-off and strength than conventional CIP method. © 2017 Trans Tech Publications, Switzerland.

Juhyung L.,Geotechnical Engineering Research Institute | Do J.,North Carolina State University
Geotechnical Special Publication | Year: 2017

In this study, a new type of suction pile foundation for floating structures, namely group suction piles, was proposed to improve the shortcomings of conventional single suction piles. Small-scale model tests were performed to estimate the horizontal behavior of single suction piles and group suction piles with different pile spacing (2, 3 and 4 times the pile diameter) under various loading conditions in terms of loading locations and inclinations. The horizontal behavior of group suction piles with different pile spacing was analyzed for various loading locations and load inclinations based on the model tests. For the given group pile configurations (a group pile having 9 component piles with a pile formation of 3 x 3), the horizontal resistance increased with increasing pile spacing. The maximum ultimate horizontal resistances were found at the loading locations of 50% of the embedded depth. Unlikely in the single suction pile case, the significantly maintained residual resistances were found for group suction piles. The residual resistances of group suction piles were at least higher than 40% of the corresponding ultimate horizontal resistances. © ASCE.

Cho J.W.,Geotechnical Engineering Research Institute | Lee J.H.,Geotechnical Engineering Research Institute | Choi E.K.,GI Co. | Kim S.W.,GI Co.
Key Engineering Materials | Year: 2017

This study aims to develop eco-friendly materials that can reduce the high unit weight of carbonate cement, as typical ground improvement material, and the release of harmful substances. Silicate binder, which is an inorganic matter based on a silicate mineral, includes kaolin, illite and metakaolin. A silicate mineral is made into silicate binder through continuous weathering. Most clay minerals belong to this silicate binder. This study conducted a preliminary study on the strength properties of feldspar powder with high activity. A specimen was made using various silicate material sources such as feldspar, metakaolin, silica fume, illite, dolomite and silica stone. This study analyzed the uniaxial compressive strength according to the type and particle size of silicate binder. The analysis result showed that the uniaxial compressive strength of a specimen using feldspar powder as silicate binder was highest. In particular, the compressive strength of a specimen where silicate powder was added as binder was higher compared to normal cement. This means that feldspar powder with high activity can be utilized as an eco-friendly resource that can replace cement. © 2017 Trans Tech Publications, Switzerland.

Park J.H.,Geotechnical Engineering Research Institute | Chung M.,Geotechnical Engineering Research Institute | Huh J.,Chonnam National University
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2015

For the implementation of the LRFD in practice, a case study on an actual bridge foundation design using both the ASD and the LRFD is comprehensively conducted. The bridge considered in this study is a 5-span (230m long span length) and, 464m-long concrete cable-stayed girder bridge, which foundation consists of drilled shafts socketed in weathered rock. The Bayesian theory was implemented to update distributions of resistances followed by the resistance factors. The result showed that the LRFD method can contribute to economical foundation designs guaranteeing the probabilities of foundation failure do not exceed the quantitative target failure probability. Furthermore, Bayesian-implemented LRFD was found to give more cost-savings than non-Bayesian LRFD by reducing margins of safety. Copyright © 2015 by the International Society of Offshore and Polar Engineers (ISOPE).

Yeu Y.,Korea Advanced Institute of Science and Technology | Kim Y.S.,Geotechnical Engineering Research Institute | Kim D.,Incheon National University
International Journal of Civil Engineering | Year: 2016

Pile penetration and rebound amount measurements during pile driving are important to assess penetration and bearing characteristics and to guarantee assurance of pile installation. Traditional manual measurement method of penetration and rebound of piles exposes engineers under unfavorable environment of injury risk and significant vibration and noise. To improve the accuracy of pile penetration and rebound measurements and to ensure safety of engineers during pile driving, the close-range photogrammetry approach was implemented by taking a series of stereo-pair images on a pile using two charge coupled device cameras. From the field implementation, it was found that the newly developed pile penetration and rebound measurement system is accurate, safe, and convenient. © Iran University of Science and Technology 2016.

Lee C.,Geotechnical Engineering Research Institute | Park S.,Korea University | Choi H.-J.,Korea University | Lee I.-M.,Korea University | Choi H.,Korea University
Tunnelling and Underground Space Technology | Year: 2016

A novel textile-type ground heat exchanger, a so-called "energy textile", is introduced in this paper. The energy textile to be assembled in a tunnel lining is devised to function as a ground-coupled heat exchanger (GHE) to operate a ground source heat pump (GSHP) system in tunnels. A test bed of six pilot energy textile modules with various configurations was constructed in an abandoned railroad tunnel in South Korea. Long-term field monitoring was performed to measure the heat exchange capacity of each energy textile module by applying artificial heating and cooling loads on it. In the course of monitoring, the inlet and outlet fluid temperatures of the energy textile, the pumping rate, the ground temperature, and the air temperature inside the tunnel were measured continuously. Each type of energy textile modules was compared in terms of its heat exchange efficiency, which appears to be sensitive to fluctuation of air temperature in the tunnel. In addition, three-dimensional computational fluid dynamic (CFD) analyses were carried out, employing FLUENT, to simulate the field test for each energy textile module. After verification of the numerical model with the field measurement, the influence of a drainage layer on the performance of the energy textile was parametrically examined. A conventional design procedure for horizontal GHEs was used in a preliminary design of an energy textile module, taking into consideration the air temperature variation inside the tunnel over the course of one year. © 2016 Elsevier Ltd.

Mok Y.J.,Kyung Hee University | Park C.S.,Geotechnical Engineering Research Institute | Nam B.H.,University of Central Florida
Soil Dynamics and Earthquake Engineering | Year: 2016

A borehole seismic source was developed to measure horizontally-polarized shear (SH-) waves in the near surface and to improve drawbacks of conventional seismic sources. An electro-mechanical-type source, called "TahcBalm", has exceptional repeatability in generating signature SH-waves, while being sufficiently small and light to be fitted in 76 mm diameter cased or uncased boreholes. The source has been extensively used for borehole seismic testing at various locations with diverse soil and rock conditions. The cross-hole and in-hole testing signals are strong enough and allow the clear identification of the first arrival of SH-waves in all tested geologic environments. TahcBalm generates SH-waves with proper wavelength of about 1 m and 0.5 m for cross-hole and in-hole testing configurations respectively, at soil and rock sites. The source performs well in terms of data quality and ease of use. © 2015 Elsevier Ltd.

Hung L.C.,Dong - A University | Nguyen T.D.,Dong - A University | Lee J.-H.,Geotechnical Engineering Research Institute | Kim S.-R.,Dong - A University
Acta Geotechnica | Year: 2015

This paper presents a study on applicability of predicting toe bearing capacities from cone penetration test (CPT) for PHC (pretensioned spun high-strength concrete) driven piles into deep sandy deposits in the Nakdong River deltaic area west of Busan City in South Korea. Using toe bearing capacities obtained from pile driving analyzer (PDA) tests as reference values, which were reliably calibrated by on-site O-cell tests, the applicability of the CPT-based methods was evaluated using a statistical rank index (RI). A total of 82 piezocone penetration test soundings and 190 PDA test piles were used for reliability analysis in this study. Three correction steps were applied to obtain reliable PDA and CPT data sets before ranking is carried out. The RI index is combined from four criteria: (1) the best-fit line, (2) the arithmetic mean and standard deviation, (3) the cumulative probabilities, and (4) the log-normal and histogram distributions. Based on these criteria the performance of some SPT-based methods in the literature is evaluated. © 2015 Springer-Verlag Berlin Heidelberg

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