• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.467-468
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• 2010

Over the past few decades, considerable numbers of studies on the durability of concrete have been carried out extensively. The majority of these researches have been performed on sound uncracked concrete, although most of in-situ concrete structures have more or less micro-cracks. It is only recent approach that the attention has shifted towards the influence of cracks and crack width on the penetration of chloride into concrete. The penetration of chlorides into concrete through the cracks can make a significant harmful effect on reinforcement corrosion. Author of this study examined the effect of cracks on chloride penetration by short term experiment. However, it is necessary to accomplish the effect by long term experiment to get reliable goal. In this study, the long term and short term experiments were carried out. This can be useful for establishing new species model of chloride penetration through cracks in concrete.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.9
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• pp.826-835
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• 2007

Solar heat flux data is needed for thermal load prediction of launch vehicle. In order to predict the solar flux, several solar flux models have been compared and a new model is developed. Most of the models can predict well the direct solar flux, but show some errors in the scattered solar flux. The newly developed model considered isotropic and anisotropic scattered solar fluxes, and the predicted solar flux agreed well with the measured. Because the present model can be used at any longitude, latitude, day and altitude, the model would be an useful tool to predict the thermal load of the launch vehicle and the vehicles which have to consider the solar heat.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.1-8
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• 1995

One of the most destructive forces around greenhouses is wind. Wind loads can be obtained by multiplying velocity pressure by dimensionless wind force coefficient. Generally, wind force coefficients can be determined by wind tunnel experiments. The wind force coefficient distribution on a single - span arched greenhouse was estimated using experimental data and compared with reported values from various countries. The results obtained are as follows : 1. The coefficients obtained from this study agree with the values proposed by G. L. Nelson except about 0.5 of difference in the middle region of roof section. This discrepancy is mainly attributed to the dissimilarity of experimental conditions (or wind tunnel test such as Reynolds number, type of terrain, surface roughness of model, location of the lapping and measuring methods. 2. Considering that the wind force coefficients are varied along the height of a wall at wind direction perpendicular to wall, structural analysis using subdivided wind force coefficient distribution is more resonable for wall. 3. It is recommendable that wind force coefficient distribution on a roof should take more subdivision than the existing four equal divisions for more accurate structural design. 4. Structural design using wind forces close to real values is more advantageous in safety and expense.

• Aerospace Engineering and Technology
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• v.8 no.2
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• pp.113-121
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• 2009

Shaker system is used to simulate the vibration from the launch environment. The vibration tests are performed in the vertical and lateral direction. For the lateral vibration test, the slip table system is used with shaker system. For the latest large satellite, vibration test adaptor is made of the steel. But slip table of lateral vibration is made of magnesium, so there is big difference of thermal expansion ratio between slip table and vibration test adaptor. This paper encompasses the following items; verification process of thermal characteristics and overturning moment and a solution for lateral vibration test with steel vibration test adaptor.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.2
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• pp.33-56
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• 2001

It is well known fact that all rocks exhibit brittle properties and time depends strain properties (creep). An understanding of the time dependent deformation behaviour of rocks is believed to be essential in the field of civil and tunnelling. The rock and concrete creep in various forms of loading conditions and physical environment are reviewed. A comparison of creep behaviour between rocks and concrete is provided, in order to bring two existing relatively independent methods of predicting creep strain closer together. It was felt that the physical process in the creep of rocks would be similar to the process in creep of concrete. Since experiments and observations have shown that non-elastic (creep) mechanical behaviour of all crystalline solids (i.e., concrete, rocks, ceramics and refractories) and single materials have a common base. Also a comparison of the results for the accepted methods of estimating creep in rocks and concrete under - multiaxial loading was attempted to extend the knowledge of deformational characteristics of these two materials.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.5
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• pp.10-21
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• 2006

For analyze of the bearing capacity, skin friction and settlements of pile on axial compressive loading, both Load transfer tests of pile and pile loading test in field have application to commonly before pile installing. A bearing capacity of pile was affected by the characteristics of surrounding ground of pile. Especially, that is very different because of evaluation of settlement due to each soil conditions of ground depths. The ground characteristics using evaluation of bearing capacity of pile through load transfer analysis depends on N values of SPT, and then a bearing capacity of pile installed soft ground and refilled area may be difficult to rational evaluation. An evaluation of bearing capacity on pile applied axial compressive loading was effected by strength of ground installed pile, unconfined compressive strength at pile tip, pile diameter, rough of excavated surface, confining pressure and deformation modules of rock etc and these are commonly including the unreliability due to slime occurred excavation works. Load transfer characteristics considered ground conditions take charge of load transfer of large diameter pile was investigated through case study applied load transfer tests. To these, matrix analytical technique of load transfer using finite differential equation developed and compared with the results of pile load test.

• International Journal of Highway Engineering
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• v.8 no.3 s.29
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• pp.115-127
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• 2006

The purpose of field monitoring system in KHC-Test Road is to provide the performance data for environmental loadings from pavement surface. Among them, water content reflectometer(WCR) are used for measuring the volumetric water content of pavement subgrades. However, WCRs are not well-calibrated based on the local field conditions. A need therefore exists for improving equations for predicting water content using the proper field and laboratory calibrations. Based on the study performed, calibrations based on various soil characteristics and density conditions are well fitted to the data from fields. So, it is recommended to use the suggested general calibration of WCR to the compacted subgrade soils in test road for predicting the volumetric water content.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.2
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• pp.97-103
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• 2011

In this study, finite element analysis is performed for consolidation behavior prediction of drainage-installed soft deposits. Finite element analysis is performed under the two strain conditions as small strain with limited application and large strain for relatively thick layers, large deformation and non-linear material properties. The analysis conditions such as layer depth, loading conditions, smear effects are also changed and variation of consolidation behavior for each condition is estimated from ABAQUS program.

• Journal of the Korean GEO-environmental Society
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• v.23 no.1
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• pp.31-37
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• 2022

This study is focused on developing a technology to prevent high-strength wire net from expanding damage due to insufficient performance of the existing PVC coating net. For the test method, reference was made to ISO 17746, an international standard. In addition, as a result of referring to the test criteria, a wire net was fabricated with a width of 1,000 mm or more a size of 1 m² sample. load-displacement curve of the test results was compared to analyze how much performance was improved compared to the existing PVC coating net.

• Journal of the Korean GEO-environmental Society
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• v.24 no.3
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• pp.15-21
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• 2023

Although standards related to falling stone facilities are established in Korea, the absorption energy of the rockfall prevention net is evaluated from the passage of rockfall and destruction of the rockfall prevention net on field test. The existing PVC coating net does not sufficiently suppress the rockfall load and tears frequently occur, and a high-strength wire rockfall net was developed to prevent. In this study, the performance was analyzed through field tests of the existing PVC coating net and the developed high-strength rockfall net (1,000 MPa, 2,000 MPa).