• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.881-891
• /
• 2008

The purpose of the present study is to investigate the influence of seasonal temperature variation on the thermal stresses in roller compacted concrete dam(RCD) structures. Using the finite element code, DIANA performs 2-D transient temperature and resultant stress analysis for RCD. Time variability of the mesh geometry is considered in order to simulate successive phases of the structure's construction. The main analysis variables are construction sequence, concrete temperature and ambient temperature. The results show principal tensile stress of hot-weathering concrete is higher than that of cold-weathering concrete. In some case the index of thermal cracking excesses 1.0, RCD also needs thermal management on placing temperature according to weather condition.

• Computers and Concrete
• /
• v.16 no.1
• /
• pp.125-140
• /
• 2015

This paper describes the numerical calculation of elastic properties of a simulated microstructure of cement paste from very early age, when most previous models fail to give accurate results. The development of elastic properties of tricalcium silicate pastes was calculated by discretising a numerical resolution-free 3D vector microstructure to a regular cubic mesh. Due to the connections formed in the microstructure as an artefact of the meshing procedure, the simulated elastic moduli were found to be higher than expected. Furthermore, the percolation of the solids was found to occur even before hydration started. A procedure to remove these artefacts, on the basis of the information available in the vector microstructures was developed. After this correction, a better agreement of the experimental results with calculations was obtained between 20% and 40% hydration. However, percolation threshold was found to be delayed significantly. More realistic estimates of percolation threshold were obtained if either flocculation or a densification of calcium silicate hydrate with hydration was assumed.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.11a
• /
• pp.173-178
• /
• 2008

This is green roof bottom system which composed by aluminum valve and glass fiber together as major reinforcement, so the cooper sheet can have root proof, and using recycled tire gel-type membrane waterproofing system which dost not contains VOCs. The copper sheet reduce the plants' root growing, so it helpes to maintain the waterproofing layer and stability of root proofing. Gel type membrane waterproofing system can do waterproofing, stress dispersion, and reducing leakage expansion. So those two materials can help each other to make green roof bottom layer would have the stability and durability.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2018.05a
• /
• pp.261-262
• /
• 2018

In this study, the quality of recycled aggregate for concrete was investigated as the number of recycled aggregate crushing cycles, grinder and crusher, peeling and crushing. First, the quality of density, absorption ratio and solid content was improved as the separation distance decreased and the number of crushing increased, depending on the number of crushing of recycled aggregate and the distance between mantle and cone cave. The quality of density, absorption ratio and solid content was improved as the wire mesh used in striking plate and the number of hammers increased, depending on the type of striking plate and the number of hammers.

• Journal of Drive and Control
• /
• v.10 no.2
• /
• pp.30-36
• /
• 2013

Tractor is a farm vehicle that is designed to provide a high tractive effort at low speed. It is used for versatile agricultural tasks such as hauling a trailer, tillage, mowing and construction work. Most older tractors use a manual transmission. However, as the intensity of work increases, tractors equipped with automatic transmission become popular due to the work convenience. In order to give the operator a large degree of control in field work, 24 gears with automatic 8-speed and manual 3-speed are arranged in transmission. This paper deals with the gear train that is designed for 8-speed automatic transmission by the engagement of multi-disk clutches. The gear ratio for each speed as well as power transmission mechanism is analyzed through velocity analysis. In addition, constraints of mesh gear ratio are derived by investigating the power flow path in velocity diagram for the given 8-speed gear ratio.

• Ocean Systems Engineering
• /
• v.5 no.1
• /
• pp.31-40
• /
• 2015

Three dimensional (3D) non-linear finite element analysis of offshore pipeline is investigated in this work with the help of general purpose software Abaqus. The general algorithm for the finite element approach is introduced. The 3D seabed mesh, limited to a corridor along the pipeline, is extracted from survey data via Fledermous software. Moreover soil bearing capacity and coefficient of frictions, obtained from the field survey report, and are introduced into the finite element model through the interaction module. For a case of study, a 32inch pipeline with API 5L X65 material grade subjected to high pressure and high temperature loading is investigated in more details.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.6 no.2
• /
• pp.196-204
• /
• 1994

Studied was impact assessment of sea dike construction in Saemankeum. To represent complexity of the geometry and topography of the region a flexible finite grid system are adopted. Combined fine and coarse meshes based on automatic mesh generator were applied in pre-processing. A nonlinear periodic finite element model. TEANL, was implied in this analysis, which gave good results compared to the observed data. It was predicted that the front region of dike connecting Shinsi-Karyeok-Daehang-Pyunsan will behave as a closed rectangular bay with wide width, which may affect significantly to the circulation and dispersion mechanism in the region.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05a
• /
• pp.39-40
• /
• 2011

The purpose of this study is to select a conductive resistor as high energy efficiency through analysis of the heating properties by induction heating. The result of this study, the heating properties is capable of weaken cementitious joint in 10~30 seconds when using the conductive resistor with wire mesh or punching metal. Although the steel is higher temperature than SUS304, SUS304's heating properties are more uniform.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05a
• /
• pp.3-4
• /
• 2011

The purpose of this study is to suggest basic data for development optimal disassembly manufacturing system during analysis pore structure and heating properties of cementitious joint using conductive resister by induction heating. From the results, we knew cementitious joint is weak easily by heating of conductive resister, such as wire mesh, punching metal, and steel fiber, from induction heating.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2011.05a
• /
• pp.37-38
• /
• 2011

This study is to analyze and compare improved curing sheet with blue sheet in order to verify the performance related to tensile stress. As results, it is confirmed that improved curing sheet(MP+BBS1) is better than the blue sheet at using field already. Synthetically, curing sheet improved by MP is analyzed to be available instead of the original because it is superior to tensile stress.