• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.8
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• pp.3719-3725
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• 2012

Due to the recent shortage of well-graded river sand resulting from a rapid growth of concrete construction, sea sand, crushed sand, and etc. are increasingly used instead. It is, however, well noted that non-washed sea sand leads to corrosion of the reinforcing steel in concrete, and thus eventually results in damage to concrete. Also, the crushed sand is not being widely used, since it is difficult to maintain the allowable amount of passing 0.08mm sieve and to adjust grading. On the other hand, because the fine sand of Nakdong-River has a poor grading but good quality as a fine aggregate for concrete, it is strongly needed to investigate the fine sand as an alternative fine aggregate. Thus, the purpose of this research is to evaluate the physical properties of the fine sand of Nakdong-River to utilize it actively as a fine aggregate. For this purpose, after the sand samples were collected according to typical location of main stream of Nakdong-River, the physical properties such as density in oven-dry condition, grading, unit volume mass, and etc. of them were estimated. It was observed from the test results that physical properties of the fine sand of Nakdong-River except grading were found to be excellent.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.207-214
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• 1997

Strength experimental on mortar which use Quenched Blast-Furnace Slag as aggregate was carried our for a fundamental study of application possibility of Quenched Blast-Furnace Slag as aggregate. It gives the following results. The strength of mortar use Quenched Blast-Furnace Slag is decrease as substitution rate is higher. As W/C rate increase, the strength decrease, but the strength decrease of fine aggregate rate 1:3 is lower than 1:2. The relation with fine aggregate is that the amount of fine aggregate is inversely proportional to strength. Th relation with age is proportional to strength and strength rate of going is lower than general mortar in 28 age the change of strength proportionately with W/C rate is that as W/C rate increases, th strength is drop ; it shows that it has same tendency as general mortar sand or crushed sand, but while W/C rate increase the strength is as high as general mortar. The reason can be assumed that water content per unit needed to Quenched Blast-Furance Slag is more than in case of sand. In addition, the relation with substitution rate is that the strength is the strongest at substitution rate 25% and 50% ; that is , sometimes it is higher than mortar which use sand 100%. In addition, long age strength of mortar which use Quenched Blast-Furnace Slag as aggregate is about to be studied in the last.

• Geomechanics and Engineering
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• v.30 no.2
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• pp.211-218
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• 2022

This study characterizes Proctor and geophysical properties in a broad range of grading and fines contents. The results show that soil index properties such as uniformity and fines plasticity control the optimum water content and peak dry unit trends, as well as elastic wave velocity. The capillary pressure at a degree of saturation less than S = 20% plays a critical role in determining the shear wave velocity for poorly graded sandy soils. The reduction in electrical resistivity with a higher water content becomes pronounced as the water phase is connected A parallel set of compaction and geophysical properties of sand-kaolinite mixtures reveal that the threshold boundaries computed from soil index properties adequately capture the transitions from sand-controlled to kaolinite-controlled behavior. In the transitional fines fraction zone between F_F ≈ 20 and 40%, either sand or kaolinite or both sand and kaolinite could dominate the geophysical properties and all other properties associated with soil compaction behavior. Overall, the compaction and geophysical data gathered in this study can be used to gain a first-order approximation of the degree of compaction in the field and produce degree of compaction maps as a function of water content and fines fraction.

• Journal of the Korean Geotechnical Society
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• v.32 no.2
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• pp.53-62
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• 2016

Among several factors controlling soil compaction, temperature is the factor that varies with region and season. Although earthwork is performed in many projects in the cold regions of the earth, studies on quantifying soil compaction associated with temperature are limited. This experimental study investigates the temperature effect on the soil compaction of cohesionless soil. Jumunjin sand was selected for the tests to represent cohesionless clean sand, which is widely used as an engineering fill at petrochemical projects such as northern Alberta of Canada and Russia. The laboratory test program consists of performing a series of standard proctor tests varying temperature of soil samples ranging from $-10^{\circ}C$ to $17^{\circ}C$. Test results indicate that soil specimen volume expansion occurred from bulking and its range was 0% to 6% with zero above temperature. For increasing temperature from $0^{\circ}C$ to $17^{\circ}C$, water content corresponding to maximum volume (minimum dry unit weight) was decreased and water content corresponding to minimum volume (maximum dry unit weight observed after reaching minimum dry unit weight) was slightly increased with increasing temperature. In zero below temperature, dry unit weight gradually decreased with increasing water content. In this case, no bulking effect was found and soil specimen volume increased due to the higher unit volume of ice.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.349-356
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• 2010

Analysis of high-resolution seismic profiles acquired from the southeastern continental shelf of Korea reveals that the late Quaternary transgressive deposits consist of six seismic units created in response to sea-level rise. These units with different seismic facies and geometry can be grouped into two distinct depositional wedges (paralic and marine) bounded by a ravinement surface. The paralic component underlying the ravinement surface consists of the sediment preserved from shoreface erosion and contains incised-channel fill, ancient beach-shoreface deposit and estuarine deposit. The top of paralic unit is truncated by a ravinement surface and overlain by marine component. The marine component consists of the sediment produced through shoreface erosion during landward transgression and contains mid-shelf sand sheet, mid-shelf sand ridge and inner shelf sand sheet. Such transgressive stratigraphic architecture of six sedimentary units is controlled by a function of lateral changes in the balance among rates of relative sea-level rise, sediment input and marine processes at any given time.

• Geophysics and Geophysical Exploration
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• v.8 no.4
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• pp.243-250
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• 2005

Analysis of high-resolution seismic profiles acquired from the inner shelf off the southern coast of Korea reveals that the inner shelf sequence can be divided into three stratigraphic units formed after the Last Glacial Maximum (LGM). Unit I is characterized by complex seismic facies including semi-transparent, stratified, and hummocky reflections on seismic records. It consists of sandy mud or muddy sand, deposited under estuarine environment during the post-glacial transgression. Unit II acoustically shows semi-transparent or hummocky reflections and consists of sand with gravels and shell debris, produced by shoreface erosion during the transgression. Unit III is characterized by transparent or semi-transparent seismic facies and consists of mud originated from the Nakdong and Seomjin rivers during recent highstand of sea level. Unit III is confined to the inner shelf with an extenal form of stratal wedge.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.3
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• pp.1-9
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• 2001

The purpose of this study was to evaluate the burning impacts of the surface and crown fire occured in yongsan-ri meongsok-myun of chinju-city, Gyeongnam. Environmental influences like surface runoff and soil erosion changes were investigated by comparisons analysis between burned and unburned area about some initial effects after fire. The results obtained from this study were as followed; 1. The average amount of surface runoff in burned area was more 1.7 times than in unburned area. But it was gradually tend to decrease in burned area as times passed. 2. Factors significantly correlated to amount of surface runoff in burned area shown in order to unit rainfall, accumulated rainfall and sand content, as 0.9466 of multiple correlation coefficient, where as the factors in unburned area were unit rainfall, soil erosion, bulk density and soil hardness, as 0.9738 of multiple correlation coefficient. 3. The average amount of soil erosion in burned area was more 11.2 times than in unburned area. But it was gradually tend to decrease in burned area as times passed. 4. Factors significantly correlated to amount of soil erosion in burned area were surface runoff and unit rainfall, as 0.6305 of multiple correlation coefficient. The factors in unburned area shown in order to surface runoff, sand content, bulk density and unit rainfall, as 0.7879 of multiple correlation coefficient.

• Journal of the Korea Institute of Building Construction
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• v.19 no.4
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• pp.313-322
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• 2019

This study is to compare and analyze the physical and strength properties of lightweight concrete using domestic lightweight aggregate by replacement ratio of artificial lightweight fine and coarse aggregate after considering low cement mixture and pre-wetting time. The slump, unit weight, compressive strength and split tensile strength of lightweight concrete with domestic lightweight aggregate were measured. As test results, the slump of lightweight concrete by replacement ratio of lightweight fine aggregate increased as the replacement ratio of lightweight fine aggregate increased. The unit weight of lightweight concrete using 100% of lightweight fine aggregate was about 10.4% lower than that of the lightweight concrete with natural sand. In addition, the unit weight of lightweight concrete by replacement ratio of lightweight coarse aggregate increased with the increase of the ratio of LWG10(5~10mm). The compressive strength of lightweight concrete with lightweight fine and coarse aggregate increased as the replacement ratio of lightweight fine aggregate increased. The compressive strength of lightweight concrete with natural sand and LWG10 was 30 to 31MPa regardless of the replacement ratio of the lightweight coarse aggregate after 7 days.

• Environmental Engineering Research
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• v.14 no.1
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• pp.41-47
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• 2009

Column experiments were performed in this study to investigate humic acid adhesion to iron oxide-coated sand (ICS) under different experimental conditions including influent humic acid concentration, flow rate, solution pH, and ionic strength/composition. Breakthrough curves of humic acid were obtained by monitoring effluents, and then column capacity for humic acid adsorption ($C_cap$), total adsorption percent (R), and mass of humic acid adsorbed per unit mass of filter media ($q_a$) were quantified from these curves. Results showed that humic acid adhesion was about seven times higher in ICS than in quartz sand at given experimental conditions. This indicates that humic acid removal can be enhanced through the surface charge modification of quartz sand with iron oxide coating. The adhesion of humic acid in ICS was influenced by influent humic acid concentration. $C_cap$ and $q_a$ increased while R decreased with increasing influent humic acid concentration in ICS column. However, the influence of flow rate was not eminent in our experimental conditions. The humic acid adhesion was enhanced with increasing salt concentration of solution. $C_cap$, $q_a$ and R increased in ICS column with increasing salt concentration. On the adhesion of humic acid, the impact of CaCl2 was greater than that of NaCl. Also, the humic acid adhesion to ICS decreased with increasing solution pH. $C_cap$, $q_a$ and R decreased with increasing solution pH. This study demonstrates that humic acid concentration, salt concentration/composition, and solution pH should be controlled carefully in order to improve the ICS column performance for humic acid removal from water.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.5
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• pp.160-170
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• 2003

A pilot study was performed to examine the feasibility of intermittent slow sand filtration for agricultural reuse of reclaimed water. The effluent of biofilter for 16-unit apartment was used as influent to the slow sand filtration system at 0.6 $m^3$/day loading rate using 15 seconds spray in every 10 minutes on the about 1 $m^2$ surface area and 0.5 m depth. The influent concentrations of total coliform (TC), fecal coliform (FC) and E. coli were in the range of 10.000 MPN/100 mL. and they were reduced to less than 1,000 MPN/100 mL after filtration with average of 320, 270, and 154 MPN/100 mL, respectively, showing over 95 % removal. Turbidity and SS were improved effectively and their average concentration was reduced to 0.8 NTU and 1.7 mg/L, respectively, and removal rate was about 50 %. Average BOD and COD concentrations were also reduced substantially to 2.6 and 25.8 mg/L with about 55 and 21 % removal rate, respectively. Nutrients removal was relatively low and removal rate for T-N and T-P was low however, remaining nutrients might be beneficial and less concerned in case of agricultural reuse. The concentration of biofilter effluent used in this experiment was in the range of secondary treatment effluent but slightly stronger than the one from existing wastewater treatment plants (WWTPs). Therefore, intermittent slow sand filtration might be also applicable to the effluent from WWTPs as long as its agricultural reuse is available. Considering stable performance and effective removal of bacterial indicators as well as other water quality parameters, low maintenance, and cost-effectiveness, the intermittent slow sand filtration was thought to be an effective and feasible alternative for agricultural reuse of reclaimed water. This paper is a preliminary result from pilot study and further investigations are recommended on the optimum design parameters before full scale application.