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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

Kim S.Y.,Korea University | Hong W.-T.,Korea University | Lee J.-S.,Korea University | Kim Y.,Geotechnical Engineering Research Institute
Proceedings of the 5th International Conference on Geotechnical and Geophysical Site Characterisation, ISC 2016 | Year: 2016

As an interest in cold region resource development increases, infrastructure constructions on frozen soils have been actively conducted. Thus, the investigation of the frozen soils is fundamental and essential to ensure the stability of frozen ground. The goal of this study is to estimate the strength of the frozen soils by the instrumented dynamic cone penetrometer. The dynamic cone penetrometer is incorporated with strain gauges and accelerometer at the cone tip to figure out transferred energy through rods. During dynamic penetration phase, a rod guide is located on the frozen soils to prevent eccentricity of impact. Specimens are prepared with sand-silt mixture at the silt fraction of 30 % in weight. The relative density and the degree of saturation are of the soils is 60 % and 10 %, respectively. The specimens are located in the freezing chamber at sub-zero temperature to freeze under the specified vertical stresses for simulating frozen ground. The dynamic penetration tests are conducted after freezing phase. Experimental results show that as the vertical stress increases, the dynamic cone penetration index which represents the strength of the frozen soils decreases. The force signal increases and the velocity estimated by accelerometer decreases as the vertical stress during freezing and penetrating phases increases. This study suggests that instrumented dynamic cone penetration test may be suitable for the investigation of the strength of the frozen soils. © 2016 Australian Geomechanics Society.

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.

Chang I.,Geotechnical Engineering Research Institute | Prasidhi A.K.,Samsung | Im J.,Korea Advanced Institute of Science and Technology | Shin H.-D.,Georgia Institute of Technology | Cho G.-C.,Korea Advanced Institute of Science and Technology
Geoderma | Year: 2015

Desertification and soil degradation are becoming more serious due to global warming and concurrent extreme climate events. Although anti-desertification efforts have been mounted worldwide, most undertakings have shown poor performance because of failure to consider soil and geotechnical aspects. Soil erosion is accelerated by reductions in soil cohesion and water retention due to the transfer of fine particles from the original ground. Thus, soil internal cohesion must be recovered to ensure effective and reliable anti-desertification attempts. In this study, soil treatment using biopolymers is suggested as an alternative method to prevent soil erosion and for revitalization, taking into consideration engineering and environmental aspects. Even as a relatively small part of the soil mass (i.e., 0.5-1.0%), biopolymers in soil have the positive potential to significantly reduce the erodibility of soil by enhancing inter-particle cohesion. Moreover, biopolymer treatment also improves both vegetation germination and soil water retention characteristics against evaporation, and therefore can provide suitable environments for plants and crops used as a desertification countermeasure in arid and semi-arid regions where annual precipitation is limited. We suggest combining biopolymers with pre-existing anti-desertification efforts (e.g., afforestation and windbreaks) on desert fronts (i.e., boundaries between arid and semi-arid regions) for best efficiency. © 2015 Elsevier B.V.

Choi S.-Y.,U and G I and T Co. | Gang S.-M.,U and G I and T Co. | Choi B.-H.,Geotechnical Engineering Research Institute | Jo Y.-W.,U and G I and T Co.
ACRS 2015 - 36th Asian Conference on Remote Sensing: Fostering Resilient Growth in Asia, Proceedings | Year: 2015

A sudden and rapid rise in global abnormal climate frequently causes typhoons and floods, among other disasters. These natural disasters inflict national economic and social damage, and threaten the safety of SOC (Social Overhead Capital) facilities. In particular, among SOC facilities, damage, caused to riverside and waterside structures, not only triggers areas inside and outside of jetties, but also lead to the loss of evacuation paths, but also brings about the combined damage of human casualties and social and economic damage. In response to disasters, speedy decision making, including the provision of disaster evacuation paths, is required, and the decision-making must use the spacetime information combining the disaster and damage information, and SOC infrastructure information. Such information is currently sporadically gathered by the government and relevant agencies, making it difficult to integrate the management thereof. Thus, for the speedy disaster response, the integrated management of such information is needed, and the creation of safety and damage information on SOC infrastructures is needed. Also, given the nature of the disaster and damage information, its spacetime convergence is needed, so the development of the inventory management and linkage system, involving the integration of relevant information, for supporting disaster response decision-making, is needed. Thus, based on inventory management/linkage modules, this study seeks to develop an inventory prototype. Detailed design for the development the said modules was conducted. The functions of the modules consisted of five detailed modules; the data transmission/reception module designed for gathering the sporadically managed disaster/damage information, the filtering module designed for standardizing the gathered data and measuring the quality thereof, the data management module designed for verifying and optimizing the spatial information data, and the system management module designed for managing the data received from relevant agencies. The inventory prototype was developed based on this inventory management / linkage modules. To that end, first, basic theme maps were produced, and the information on facilities in TB (?) areas was constructed. Such constructed inventory system is certain to effectively provide source data for decision-making for proactive damage response, and is to be used in the management of SOC infrastructures.

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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