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Jung Y.-B.,Korea Institute of Geoscience and Mineral Resources | Park E.-S.,Korea Institute of Geoscience and Mineral Resources | Chung S.-K.,Korea Institute of Geoscience and Mineral Resources | Kim H.-Y.,SK Engineering and Construction Co.
Engineering Geology | Year: 2011

A new method of storing LNG (Liquefied Natural Gas) in a lined, hard rock cavern has been developed and verified by the construction and operation of a pilot plant in Korea. Creation of an ice ring is one of the core techniques in LNG storage in a lined rock cavern. The ice ring serves not only as a primary barrier against the intrusion of groundwater into an LNG cavern, but also as a secondary protection in case of leakage of LNG. Dry conditions within an ice ring protect a containment system against cracking due to the freezing of groundwater. Therefore, it is crucial to estimate and control the thickness and location of the ice ring when designing and operating an underground LNG storage cavern. In order to find suitable numerical scheme that simulates field results, the behavior of the ice ring around the pilot LNG cavern is investigated by hydro-thermal-coupled analyses. Through coupled analyses composed of three cases (CASE_1: constant thermal properties, CASE_2: temperature-dependent thermal properties, and CASE_3: phase change consideration in addition to CASE_2), the position and thickness of the ice ring, the temperature distributions and the groundwater level around the cavern are estimated and compared with measured data obtained from the pilot LNG cavern. The results show that the temperature distribution and groundwater level around the LNG cavern can be estimated reliably within an error of less than 4 °C and 1.0. m, respectively. The accuracy of numerical modeling is increased when the temperature-dependent properties are taken into account. The effect of phase change during freezing and thawing of groundwater is relatively small due to the dryness inside the ice ring and low porosity of the rock mass. These results imply that the adopted numerical method can be applied to full-scale underground LNG caverns for the control of the ice ring. © 2010 Elsevier B.V. Source

Park E.-S.,Korea Institute of Geoscience and Mineral Resources | Jung Y.-B.,Korea Institute of Geoscience and Mineral Resources | Song W.-K.,Korea Institute of Geoscience and Mineral Resources | Lee D.-H.,SK Engineering and Construction Co. | Chung S.-K.,Korea Institute of Geoscience and Mineral Resources
Engineering Geology | Year: 2010

This paper reports the background information and the initial results obtained from the pilot underground LNG (liquefied natural gas) storage cavern in Korea, where all natural gas is stored in the condition of liquid phase. Many attempts have been made in the past to store LNG underground in unlined containment, though without success. A new concept for storing LNG in a lined rock cavern has been developed to provide a safe and cost-effective solution. It consists of protecting the host rock against the extremely low temperature and providing a liquid and gas tight liner. One of the most significant problems related to underground storage of cryogenic material is the need to prevent the leakage of liquid and gas from the containment system to the rock mass caused by tensile failures due to shrinkage of the rock mass around the caverns. In order to verify the technical feasibility of this storage concept, a pilot plant was constructed for storing Liquefied Nitrogen and has been in operation since January 2004, though has now been decommissioned. The overall monitored results from the pilot operations confirmed that the construction and operation of underground LNG storage in lined rock caverns is technically feasible for a rock engineering point of view. The results of this study may promote the first ever real scale underground LNG storage system in a rock cavern in the world. © 2010. Source

Kwon K.,Sogang University | Hwang Y.H.,SK Engineering and Construction Co. | Kang H.,Sogang University | Kim D.,Sogang University
Transactions of the Korean Society of Mechanical Engineers, B | Year: 2013

In this study, we performed a numerical study of hydrogenfair combustion in the combustion chambcr of an ultra micro gas turbine. The supply flow rate and equivalence ratio are used as variables, and the commercial computational fluid dynamic program (STAR-CCM) is used for the numerical study of the combustion. The flow rate significantly affccts the flame position, flame temperature, and pressure ratio between the inlet and the outlet. The flame position is closc to the outlet in the combustion chamber, and the flame temperature and pressure ratio monotonously increases with the supply flow rate. The change in the equivalence ratio does not affect the flame position, The maximum flame temperature occurs under stoichiometric conditions. © 2013 The Korean Society of Mechanical Engineers. Source

Lee T.S.,Hanyang University | Kim D.-H.,SK Engineering and Construction Co. | Lee D.W.,Jeju National University
KSCE Journal of Civil Engineering | Year: 2011

This study focuses on developing a competency model for project construction team and project control team service, which are the essential responsibilities of construction companies, in order to provide a basic framework for manpower development including employment, education, performance measurement, and organizational ability improvement. Together, these attributes comprise the basics of human resource management and reflect the key characteristics of construction companies. This study analyzed several previous competency model studies, and derived job competency items from a questionnaire-based survey of corresponding job performers centering on various existing competency items established with respect to the characteristics of construction companies. In addition, through interviews with a specialist group, this study derived weights for setting competency levels and facilitating competency evaluation and formulated a project construction team and project control team affair competency model for construction companies. This study tested the validity of the formulated model by analyzing its correlation with the performance of actual construction projects. © 2011 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg. Source

Lee C.,Chonnam National University | Hong S.-J.,Seoul Development Institute | Kim D.,SK Engineering and Construction Co. | Lee W.,Korea University
Marine Georesources and Geotechnology | Year: 2015

A series of 1-D consolidation tests are performed on the undisturbed and remolded specimens for Busan and Incheon clays in order to propose empirical correlations predicting the compression index of natural clays. For both clays, the compression index is found to correlate best with wnand to have the weakest correlation with ILamong the four soil properties (wL, Ip, wn, IL). It is observed that, for Incheon clay, the multi-variable equation (wLand wn) moderately improves the accuracy of the empirical correlation, while, for Busan clay, it provides negligible improvement compared with the equations with a single soil property. In this study, the sedimentation state of natural clay is defined as the difference in the void ratio between the natural and remolded clays at yield stress (Δer,), and the prediction equations that can consider the sedimentation state are suggested. It is noted that, for Busan clay, the equations considering the sedimentation state provide a significantly better accuracy than the equations with multiple soil properties, whereas, for Incheon clay, both types of equations provide a similar accuracy. © 2015, Taylor & Francis Group, LLC. Source

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