• Journal of the Korean Society for Advanced Composite Structures
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• v.2 no.2
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• pp.26-33
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• 2011

Recently, the use of buried glass fiber reinforced plastic (GRP) pipes is widespread and ever increasing trend in the industry. GRP pipes are attractive for use in harsh environments, such as for the collection and transmission of liquids which are abrasive and/or corrosive. The structural behavior of a GRP pipes buried under the ground is different from that of a rigid one made of concrete or clay, for example. A GRP pipe buried under the ground is deflected circumferentially by several percent and the stresses in the pipe are mainly compressive stresses. A GRP pipes has been introduced by a number of manufacturers for selection and used by underground pipeline designers. In all cases, the modified Spangler's equation is recommended by these manufacturers for predicting the ring deflection of these pipes under dead and live loads. In this paper, the ring deflection of buried GRP pipe is evaluated and discussed based on the result of analytical investigation.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.287-295
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• 2008

Rock slope has a variety of irregular discontinuities and represents a discontinuous mass. Rock joint plays an important role of control hydraulic and mechanic movements in the rock mass. These characteristics between hydraulic and mechanic movements at the rock joints could be represent difference. Therefore they are quiet important factor for slope design. In this study the weathered rock slopes were carried out to analysis of slope stability and geophysical survey. The electrical resistivity survey with dipole-dipole array conducted five profiling sites, and SWEDGE and SLIDE for slope stability analysis were applied on 20 rock slopes far assessment of slope stability and understand to geological situations due to the weathering.

• Journal of the Korean Society of Marine Environment & Safety
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• v.16 no.2
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• pp.161-168
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• 2010

We conducted a field survey of the generation and development of the delta area of the Nakdong River estuary, Korea. To examine deposition and erosion of the barrier islands, we observed the spatiotemporal variations of sediment transport and quantitatively estimated the settling velocity of coastal sediment. For the field survey, we established two survey sites off the coasts of Jinu Island and Doyodeung, which had shown rapid variations in deposition and erosion. At these sites, we measured the net surface elevation change of the bottom level at approximately 1-month intervals. Main findings were summarized as follows. (1) Calculated daily deposition and erosion velocity during the observation period ranged from -1.39 to 3.56cm/day at Jinu Island and from -4.0 to 3.07cm/day at Doyodeung, respectively. (2) Although two typhoons passed by the study area during the observation period, the maximum net surface elevation was larger in October than during the passage of those typhoons.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.72-79
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• 2015

An efficient and practical reliability evaluation method is proposed for the coastal structures in this paper. It is capable of evaluating reliability of real complicated coastal structures considering uncertainties in various sources of design parameters, such as wave and current loads, resistance-related design variables including Young's modulus and compressive strength of the reinforced concrete, soil parameters, and boundary conditions. It is developed by intelligently integrating the Latin Hypercube sampling (LHS), Monte Carlo simulation (MCS) and the finite element method (FEM). The LHS-based MCS is used to significantly reduce the computational effort by limiting the number of simulation cycles required for the reliability evaluation. The applicability and efficiency of the proposed method were verified using a caisson-type breakwater structure in the numerical example.

• Journal of Ocean Engineering and Technology
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• v.29 no.2
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• pp.175-185
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• 2015

Jack-up type WTIV(Wind Turbine Installation Vessel) is used to avoid the effects of waves when installing wind turbines in the Southwest Sea of South Korea. During the preloading procedure, unexpected penetration may cause some risks such as excessive penetration or punch-through failure. To ensure the safety of the WTIV during preloading, the bearing capacities should be evaluated based on the soil data at each borehole. Eight boreholes (OW-1 to -8) have been drilled in the Southwest Sea of South Korea. The bearing capacities of a spudcan designed to be used in this district are calculated using both a conventional analysis and finite element analysis with the soil properties of OW-1 to -8. A finite element analysis is carried out for OW-1, -3, and -4 to gain an in-depth understanding of the soil behavior during the penetration. OW-1, -3, and -4 are representative boreholes for a strong layer overlying a soft layer, a general soft layer, and a soft layer overlying a strong layer, respectively. The resultant bearing capacity curves versus the depth of the numerical analysis are compared with the conventional method. The results show that the conventional analysis is conservative. Case studies for different spudcan areas and shapes are also conducted to seek an appropriate spudcan type for the Southwest Sea of South Korea. Finally, a spudcan with a rectangular shape and a bearing area of $112.8m^2$ is selected.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.5
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• pp.23-29
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• 2008

This study investigates the dynamic instability of strength-limited bilinear single degree of freedom (SDF) systems under seismic excitation. The strength-limited bilinear hysteretic model best replicates the hysteretic behavior of the steel moment resisting frames. To estimate the dynamic instability of SDF systems, the collapse strength ratio is used, which is the yield-strength reduction factor when collapse occurs. Statistical studies are carried out to estimate median collapse strength ratios and those dispersions of strength-limited bilinear SDF systems with given natural periods, hardening stiffness ratios, post-capping stiffness ratios, ductility and damping ratios ranging from 2 to 20% subjected to 240 earthquake ground motions recorded on stiff soil sites. Equations to calculate median and standard deviation of collapse strength ratios in strength-limited bilinear SDF systems are obtained through nonlinear regression analysis. By using the proposed equations, this study estimated the probabilistic distribution of collapse strength ratios, and compared this with the exact values from which the accuracy of the proposed equations was verified.

• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.2
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• pp.43-56
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• 1993

The laboratory tests are performed on how the liquefaction potential of the sea dike structures on the saturated sand or silty sand seabed could be affected due to earthquake before and after construction results are given as follows ; 1. Earthquake damages to sea dike structures consist of lateral deformation, settlement, minor abnormality of the structures and differential settlement of embankments, etc. It is known that severe disasters due to this type of damages are not much documented. Because of its high relative cost of the preventive measures against this type of damages, the designing engineer has much freedom for the play of judgement and ingenuity in the selection of the construction methods, that is, by comparing the cost of the preventive design cost at a design stage to reconstruction cost after minor failure. 2. The factors controlling the liquefaction potential of the hydraulic fill structure are magnitude of earthquake(max. surface velocity), N-value(relative density), gradation, consistency(plastic limit), classification of soil(G & vs), ground water level, compaction method, volumetric shear stress and strain, effective confining stress, and primary consolidation. 3. The probability of liquefaction can be evaluated by the simple method based on SPT and CPT test results or the precise method based on laboratory test results. For sandy or silty sand seabed of the concerned area of this study, it is said that evaluation of liquefaction potential can be done by the one-dimensional analysis using some geotechnical parameters of soil such as Ip, Υt' gradation, N-value, OCR and classification of soils. 4. Based on above mentioned analysis, safety factor of liquefaction potential on the sea bed at the given site is Fs =0.84 when M = 5.23 or amax= 0.12g. With sea dike structures H = 42.5m and 35.5m on the same site Fs= 3.M~2.08 and Fs = 1.74~1.31 are obtained, respectively. local liquefaction can be expected at the toe of the sea dike constructed with hydraulic fill because of lack of constrained effective stress of the area.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.46-51
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• 2002

In subway or road construction, the vibration caused by various construction equipments influences gas pipelines directly or indirectly Especially buried gas pipelines are influenced by the blast occurred near the pipeline buried Place. To analyze vibration response of buried gas pipeline caused by blasting works, the nonlinear behavior of ground is realized by applying equivalent linear analysis. According to the results of this analysis, the acceleration response values of gas pipeline are close to the measured values and the occurring time of peak values are agreed to the measured values. Thus, It is concluded that conventional seismic analysis mechanism can be applied to the dynamic analysis of buried gas pipeline.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2003.03a
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• pp.13-30
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• 2003

In this paper, a new systematic method will be introduced, in which a Rock-mass Prediction System(RPS) predicts the geological conditions and rock mass movements before tunnel excavation and the appropriate counter-measures are taken in the expected weak zones during tunnel construction. The Rock-mass Prediction System(RPS) consists of the LIM, a horizontal core drilling and a seismic exploration method(TSP/HSP). In the Rock-mass Prediction System(RPS), the seismic exploration method (TSP/HSP) gives information on the locations of the weak zones such as major faults and voids in wide-range, and the horizontal core drillings are utilized to find exact location and widths of the faults or voids near the weak zones which was predicted by the seismic exploration method (TSP/HSP). The LIM is used to find the hardness of the rock mass and small weak zones near the excavation face. The Rock-mass Prediction System (RPS) was successfully applied to the Sol-An Tunnel and the effectiveness of the system was verified.

• Tunnel and Underground Space
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• v.18 no.2
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• pp.107-117
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• 2008

In this study, the failure and deformation characteristics of steel fiber reinforced shotcrete (SFRS) which is a primary tunnel support was investigated to find out ground-support mutual behavior. To this end, a mock-up of a tunnel was made and experimented with the conditions of lateral earth pressure coefficient 0.5 and 1.0. During the tests, 11 hydraulic cylinders were used for loading. for better simulation of the lateral earth pressure effect, these cylinders were controlled separately by two groups; crown and side wall. Meanwhile, the deformation of shotcrete was measured by 11 LVDTs. Backfill material was also used fur better load transfer from hydraulic cylinders to shotcrete. For the validation of the mock-up test results, 3D numerical analysis is carried out. To do numerical analysis under the same condition as a mock-up test, the load history curve which was obtained during the test was tried to be simulated using an individual FISH routine in the numerical analysis.