• Economic and Environmental Geology
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• v.35 no.4
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• pp.347-353
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• 2002

Dominant rock types of stones used presently for cooking utensils in Korea are pyroxenite, breccia and biotite diorite. Pyroxenite and biotite diorite relatively abundant in mafic minerals have higher specific gravities of 3.0 than breccia of 2.5. Breccia shows the highest absorption (2.9%) among three stones used as cooking utensils and pH value of three stone types shows the alkaline range of 9.7 to 9.9. Among the studied stones used for cooking utensils, biotite diorite is the most durable against abrasion and has the highest strength and therefore, it is expected to be used effectively for the longest time except for other specific causes. Heavy metals such as Cu, Pb, Co, Cr and Ni were leached lower than their detection limit (0.1 ppm) regardless of reaction time and initial pH value of solution. But the leached contents of Fe are various with rock types and leaching conditions and those by acidic solution are generally 1.8 to 31 times higher than those by neutral solution. Breccia and biotite diorite show the highest leached content of Fe in cases of neutral and acidic solutions, respectively. Standard criteria of leached heavy metals and macrominerals should be studied thoroughly to utilize stones for cooking utensils of high quality which are harmless to the human body. Also it is required to examine mon detailed abiochemical properties of various stone types used for cooking utensils.

• Journal of Navigation and Port Research
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• v.30 no.8 s.114
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• pp.711-719
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• 2006

A series of geotechnical centrifuge model tests and numerical modelling have been performed to study engineering characteristics of the composite ground reinforced by both the Sand Compaction Piles(SCPs) and the deformation-reducing sheet piles. The research has covered several key issues such as the load-settlement relation, the stress concentration ratio and the final water content of the ground Totally three centrifuge tests have been conducted by changing configuration of the sheet piles, i.e., a test without the sheet pile, a test with the sheet pile at a single side and a test with the sheet piles at the both sides. In the model tests, a vertical load was applied in-flight on the ground surface. On the other hand, class-C type numerical modelling has been performed by using the SAGE-CRISP to compare the centrifuge test results using an elasto-plastic model for SCPs and the Modified Cam Clay model for the soft clay. It has been found that the sheet piles can restraint failure of foundation, thereby increasing yield stress of the ground. The stress concentration ratio was in the range of $2{\sim}4$. In addition, numerical analysis results showed reductions both in the ground heave($20{\sim}30%$) and in the horizontal movement($28{\sim}43%$), demonstrating the deformation-reducing effect of the sheet piles.

• Journal of Bio-Environment Control
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• v.15 no.2
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• pp.138-148
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• 2006

This study was carried out to evaluate the structural safety fur both the attached wind-protecting wall in greenhouse and the detached one installed outside. Regarding the attached wind-protecting wall in greenhouse, the analysis was conducted by doing a fluid-structure coupled field analysis using both CFX-5.7 and ANSYS 8.1 and also under the design condition of an instantaneous maximum wind velocity of $30.9m{\cdot}s^{-1}$. Three kinds of the width ranged from 30 to 90cm were considered in this study. With regard to the detached wind-protecting wall, the structural saffty was analyzed under the pressure difference of 1,117 Pa which corresponded to a wind velocity of $50m{\cdot}s^{-1}$ and the analytical results were also compared with theoretical ones. The result showed that there was little difference in the distribution of velocity overall and total pressure on the lateral side according to the width of the attached wind-protecting wall, but greenhouse with wind-protecting widths of 30 to 60cm has been reinforced to the extent of about 11% when compared with the case of being without the wall. The result also showed that the detached wind-protecting wall with a main-column interval of 3m was not stable so that it was necessary for the detached wind-protecting wall to be adequately reinforced to secure structural stability. Finally, there was great difference between analytical results and theoretical studies. The difference meant that there was some possibility of including errors when a theoretical study was done in three dimensional structure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.106-112
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• 2017

This paper presents a mathematical model derived from the upper-bound theorem of concrete plasticity to rationally evaluate the shear friction strength of concrete interfaces with a construction joint. The upper limit of the shear friction strength was formulated from the limit state of concrete crushing failure on the strut-and-tie action along the construction joints to avoid overestimating the shear transfer capacity of a transverse reinforcement with a high clamping force. The present model approach proposed that the cohesion and coefficient of friction of concrete can be set to be $0.27(f_{ck})^{0.65}$ and 0.95, respectively, for rough construction joints and $0.11(f_{ck})^{0.65}$ and 0.64, respectively, for smooth ones, where $f_{ck}$ is the compressive strength of concrete. From the comparisons with 155 data compiled from the available literature, the proposed model gave lower values of standard deviation and coefficient of variation of the ratios between predictions and experiments than AASHTO and fib 2010 equations, indicating that the proposed model has consistent trends with test results, unlike the significant underestimation results of such code equations in evaluating the shear friction strength.

• Journal of the Korean GEO-environmental Society
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• v.16 no.12
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• pp.37-43
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• 2015

Ground characteristics is important in tunnel structure utilizing the strength of underground. In the case of the fault fracture zone such as weak soil conditions exists in the tunnel section and groundwater leaching occurs at the same time, it happens to occur to excessive displacement or collapse of tunnel frequently. Fault fracture zone is an important factor that determines the direction of displacement and the collapse of the tunnel under construction. Behavior of fault fracture zone is determined depending on the size and orientation of the surface portion of the tunnel. If the groundwater occurs in the face of tunnel, groundwater causes displacement and collapse. And the collapse characteristics of tunnel is a major factor in determining that the time-dependent behavior. It is difficult to accurately predict groundwater leaching from the fault fracture zone in the numerical analysis method and analyze the interaction behavior of groundwater and fault fracture zone. Therefore numerical analysis method has limitations the analysis of ground water in the ground which the fault fracture zone and groundwater occurs at the same time. It is required to comprehensively predict the behavior of tunnel and case studies of tunnel construction. Thus, the location of fault fracture zone is an important factor that determines the direction of displacement and the collapse of the tunnel. In this study, behavior characteristics of the tunnel according to the location of the fault fracture was analyzed.

• Journal of the Korean GEO-environmental Society
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• v.13 no.3
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• pp.29-37
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• 2012

This study is to find out the characteristics of the behavior of Geosyntehtic Reinforced Retaining Earth Wall(GRREW) through the laboratory experiment with the reduced-scale model, and to verify the effect of reinforcement by materials of GRREW. The loading tests after combining nonwoven geosynthetic, re-bar mesh nets and drainage blocks respectively among the components of the GRREW were performed in three cases of their slopes. In the cases of the behavior analysis including all of the components of the GRREW, the maximum horizontal displacement was generated 8.4mm at the location of 0.57H in the slope of 1:0.3; 3.8mm at the location of 0.57H in the slope of 1:0.6; 3.6mm at the location of 0.86H in the slope of 1:1.0. On average, the horizontal displacements of the GRREW were reduced by 83.8% against those of the original slopes. Lastly, seepage analysis and slope stability analysis were performed by modelling section of field, to confirm the effect of installation of drainage block in GRREW. We can confirm to compare increasing the slope safe factor and decreasing ground water in accordance with drainage blocks.

• Polymer(Korea)
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• v.36 no.5
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• pp.549-554
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• 2012

It was known that triphenyl phosphate wasn't homogeneously dispersed in HDPE/EPDM/boron carbide blends, which caused the decrease in mechanical properties. HDPE, EPDM, boron carbide, and triphenyl phosphate were blended with PE-g-MAH(polyethylene-graft-maleic anhydride) as a compatiblizer for improving the miscibility of triphenyl phosphate. Tensile strength of HDPE/EPDM/boron carbide blends decreased with increasing the contents of triphenyl phosphate for flammability. However, the mechanical properties of HDPE/EPDM/boron carbide/triphenyl phosphate blends increased by the addition of compatiblizer because triphenyl phosphate was homogeneously mixed in the blend system. The homogeneous dispersibility of triphenyl phosphate was confirmed by using scanning electron microscopy (SEM). Increased thermal stability and flammability derived from high miscibility of triphenyl phosphate were confirmed by the results of thermogravimetric analysis (TGA) and limiting oxygen index (LOI). A self-extinguishing HDPE/EPDM/boron carbide/triphenyl phosphate blend was successfully fabricated with more than 21% LOI.

• Journal of Wetlands Research
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• v.22 no.4
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• pp.302-311
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• 2020

There are limitations to cope with flood damage by structural strategies alone because both frequency and intensity of floods are increasing due to climate change. Therefore, it is one of the necessary factors in the nonstructural countermeasures to collect and analyze historical flood damage records for the future flood damage assessments. In order to estimate flood damage costs in Gyeongsangbuk-do where severe flood damage occurs frequently due to geographical and climatic effects, this paper has performed the regression analysis on flood damage records over the past 20 years (1999-2018) by rainfall characteristics, which is one of the major causes of flood damage. This paper has then examined the relationship between the terrain features and rainfall characteristics in the regional regression functions, and also estimated the flood damage risk for 100-year rainfall by using the regional regression functions presented for the 22 administrative districts in Gyeongsangbuk-do excluding Ulleung-gun. The flood damage assessment shows that the relatively high damage risk is estimated for county areas adjacent to the eastern coast in Gyeongsangbuk-do. The regional damage estimate functions in this paper are expected to be used as one of the nonstructural countermeasures to estimate flood damage risk for the design or forecasting rainfall data.

• Journal of Korea Water Resources Association
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• v.46 no.6
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• pp.655-666
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• 2013

Lately, intensity and frequency of natural disasters such as flood are increasing because of abnormal climate. Casualties and property damages due to large-scale floods such as Typhoon Rusa in 2002 and Typhoon Maemi in 2003 rapidly increased, and these show the limits of the existing disaster prevention measures and flood forecasting systems regarding irregular climate changes. In order to efficiently respond to extraordinary flood, it is important to provide effective countermeasures through an inundation model that can accurately simulate flood inundation patterns. However, the existing flood inundation analysis model has problems such as excessive take of analysis time and accuracy of the analyzed results. Therefore, this study conducted a flood inundation analysis by using the Gerris flow solver that uses quadtree grid, targeting the Baeksan Levee in the Nakdong River Basin that collapsed because of a concentrated torrential rainfall in August, 2002. Through comparisons with the FLUMEN model that uses unstructured grid among the existing flood inundation models and the actual flooded areas, it determined the applicability and efficiency of the quadtree grid-based flood inundation model of the Gerris flow solver.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.413-416
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• 2008

The concrete used most in construction materials. There is an overcrowded iron dimensions use of the concrete at time of the other concrete theory on the reinforcing rod back which did congestion and compares it with this, and there are more few dimensions of the aggregate than concrete, and quantity of aggregate passage is superior in mortar than concrete. If a volume rate of the aggregate writes mortar than concrete against this, therefore, unit amount increases, and quantity of paste increases and quantity of dry shrinkage than increase concrete. However, I let I regulate lay priest distribution of the aggregate, and the results rates increase and reduce unit amount and decrease quantity of dry shrinkage, and separation resistance and the gap passage characteristics are judged because it can be it in a substitute document of very superior concrete. I came to carry out the study that I watched to let I was useful a little more and do the improvement repair of a become building wall body, a basement pillar and repair reinforcement of the assistant in the reinforcing rod back, the old age when I made congestion here. I regulated lay priest distribution of the aggregate in the study and regulated substitution rate of the aggregate (40%, 50%, 60%) and divided W/C 30%, 40% standards and produced mortar and I compared quantity of air by this, slump, compression robbery and showed it this time.