Nam-Ryong Kim

Bio: Nam-Ryong Kim is an academic researcher from K-water. The author has contributed to research in topics: Centrifuge & Shear modulus. The author has an hindex of 6, co-authored 22 publications receiving 231 citations. Previous affiliations of Nam-Ryong Kim include KAIST.

A Newly Developed State-of-the-Art Geotechnical Centrifuge in Korea

Abstract: The first large scale geotechnical centrifuge in Korea has recently been developed at KAIST under the Korea Construction Engineering Development (KOCED) Collaboratory program. A 5 m platform radius, 240 g-tons state-of-the-art geotechnical centrifuge has been installed in a new facility. The centrifuge has the unique feature of an automatic balancing system and includes parts for general testing purposes such as fluid rotary joints, slip rings, a fiber optic rotary joint and an Ethernet network system. In addition, a four degree-of-freedom in-flight robot can be equipped to simulate complex construction or in-situ testing process during centrifuge flight. In order to simulate earthquake motion during operation, a self-balancing type biaxial shaking table has also been developed. Since the KOCED program promotes collaboration and remote use, tele-presence and tele-participation environments have been implemented in this facility.

LEAP-UCD-2017 Comparison of Centrifuge Test Results

Abstract: This paper compares experimental results from every facility for LEAP-UCD-2017. The specified experiment consisted of a submerged medium-dense clean sand with a 5-degree slope subjected to 1 Hz ramped sine wave base motion in a rigid container. The ground motions and soil density were intentionally varied from experiment to experiment in hopes of defining the slope of the relational trend between response (e.g., displacement, pore pressure), intensity of shaking, and density or relative density. This paper is also intended to serve as a useful starting point for overview of the experimental results and to help others find specific experiments if they want to select a subset for further analysis. The results of the experiments show significant differences between each other, but the responses show a significant correlation, R2 ~ 0.7–0.8, to the known variation of the input parameters.

LEAP-UCD-2017 V. 1.01 Model Specifications

Abstract: This paper describes the specifications developed by and distributed to all of the centrifuge test facilities involved in LEAP-UCD-2017. The specified experiment consisted of a submerged medium dense clean sand with a 5-degree slope subjected to 1 Hz ramped sine wave base motion in a rigid container. This document describes the detailed geometry, sensor locations, methods of preparation, quality control, shaking motions, surface markers, and surface survey techniques.

A Shear Wave Velocity Tomography System for Geotechnical Centrifuge Testing

Abstract: In physical model tests using geotechnical centrifuge, it is important to evaluate soil properties during centrifugal acceleration due to the effect of stress conditions. A crosshole type shear wave velocity tomography testing system has been developed, and the distribution of maximum shear modulus in sand layers could be evaluated in the centrifuge. Piezoelectric bender elements are installed in the system as shear wave transmitters and receivers for travel time measurement. A driving and measurement system for bender element tests is prepared to be used under centrifuge operating environment. A series of tests using this system has been conducted with uniform sand samples, and the testing procedure and typical signals from bender elements are presented. Tomography inversion considering curved raypaths has been conducted using a total of 256 travel time data determined by measured signals because the first arrivals follow curved raypaths under a stress related linear variation in stiffness with depth. The maximum shear modulus variation with depth, or vertical effective stress, has been verified through comparison with resonant column test results, and the applicability of this system in general centrifuge testing has been confirmed.

A Newly Developed State-of-the-Art Geotechnical Centrifuge in Korea

Abstract: The first large scale geotechnical centrifuge in Korea has recently been developed at KAIST under the Korea Construction Engineering Development (KOCED) Collaboratory program. A 5 m platform radius, 240 g-tons state-of-the-art geotechnical centrifuge has been installed in a new facility. The centrifuge has the unique feature of an automatic balancing system and includes parts for general testing purposes such as fluid rotary joints, slip rings, a fiber optic rotary joint and an Ethernet network system. In addition, a four degree-of-freedom in-flight robot can be equipped to simulate complex construction or in-situ testing process during centrifuge flight. In order to simulate earthquake motion during operation, a self-balancing type biaxial shaking table has also been developed. Since the KOCED program promotes collaboration and remote use, tele-presence and tele-participation environments have been implemented in this facility.

Investigation of Monotonic and Cyclic Behavior of Tripod Suction Bucket Foundations for Offshore Wind Towers Using Centrifuge Modeling

Abstract: This paper performed centrifuge load tests of a tripod bucket foundation preliminarily designed as a supporting system of wind turbines and compared the results to those obtained from a test of a monopod bucket foundation. The tripod foundation prototype studied in this study has three bucket caissons, each of which is 6.5 m in diameter and 8.0 m in length. The center-to-center distance between the buckets was 26.9 m. The site is composed of an 11-m thick layer of dense silty sand overlying a thick sandy silt layer. The horizontal load was applied at a height of 33 m from the seabed floor according to the design load condition, and the vertical load was simulated by the self-weight of the model. The moment-rotation angle curves for the tripod foundations were compared with that of the monopod bucket foundation. The moment-rotation curve of the tripod was nearly bilinear, whereas that of the monopod showed a gradual decrease in slope. The yield moment for the tripod foundation was half that of the monopod, but the rotation angle for the yield moment was only 20% that of the monopod. The behavior of the tripod foundation under a cyclic load with respect to the accumulated plastic deformation has also been examined in this study. When the resultant moment of cyclic loading was smaller than the monotonic yield moment, negligible accumulated plastic deformation was observed for both one-way and two-way loading. However, when the resultant moment was higher than the monotonic yield moment, significant cumulated deformation resulted.

A GIS-based assessment of water quality pollution indices for heavy metal contamination in Tuticorin Corporation, Tamilnadu, India

Abstract: The present study was conducted to evaluate the metal pollution of groundwater in the vicinity of Tuticorin Corporation in Tamilnadu State, India, used by various pollution indices such as heavy metal pollution index (HPI), heavy metal evaluation index (HEI), and degree of contamination (DOC). Thirty-six groundwater samples were collected during the summer season (May 2013) and the concentration of metals Al, Cr, Fe, Cu, Mn, Ni, Zn, Cd, and Pb was analyzed. Consequences exhibited that groundwater was contaminated with Mn (59.12 ppb), Cu (162.41 ppb), Pb (196.15 ppb), Cr (187.12 ppb), and Cd (10.11 ppb). Correlation and factor analysis revealed that the sources of metals in groundwater in the study area are the same, and it may due to the leachates from the nearby sewage farm, industrial activity (State Industries Promotion Corporation of Tamil Nadu Limited (SIPCOT)), Buckle canal, and solid wastes dumped in the residential area. Groundwater pollution indices of HPI, HEI, and DOC revealed that most of groundwater samples belonged to the medium to high zones, which was adjacent to the polluted Buckle canal, SIPCOT industrial waste, and sewage fish farm in the coastal area. The present study points out that the metal pollution causes the degradation of groundwater quality around Tuticorin coastal corporation. These study results will be very helpful for sustainable management of groundwater resources, and they will enable planners and policymakers to evolve a strategy to solve similar problems elsewhere.