• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.1
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• pp.27-32
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• 1970

A study on the purification of the surf clam Mactra Sulcataria REEVE for the remove of sand and fecal piles was conducted in the laboratory. The sand was mostly distributed around the inhalent and exhalent siphon, mantle and gill, and were also distributed in the digestive tract including the mid-gut gland. The sand particles in the digestive tract were extremely small and their sizes were about $180\times10\mu\;to\;550\times200\mu$. It could be seen that there was little, if any, difference in the rate of sand removal when either the hanging Purification method was used or the method of laying the surf clams in thick or thin layers on the bottom of the experimental vessel was used. The surf clam removed about $50\%$ of its sand during the first hour of purification. The weight of the removed sand and fecal piles on a dry basis reached a constant value after 22 to 26 hours of purification. After 42 hours of Purification, no sand could be seen in the fecal piles. The surf clam removed the sand in its body more rapidly when it was in sea water with the pH of 8.75 than when it was in natural sea water. Also high temperature had a much greater depressing effect upon the removal of sand In the surf clam than did natural sea water. Also low salinity had greater accelerating effect upon the removal of sand in the body than did natural sea water. However the surf clam died when the salinity was $8.19\%_{\circ}$.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.352-355
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• 2004

Crushed sand is made by crushing the rocks artificially. With a wide shortage of natural river sand all over the region in Korea, demand for crushed sand are becoming increased. However, Informations as to crushed sand are insufficient. In this paper, the actual conditions of crushed sand related to producing and quality variation are investigated. 29 manufacturing company of crushed sand are reviewed. According to results, density of most crushed sand tested exceeded 2.5g/cm3, and absorption ratio meet the requirement of KS except one sample. For grain properties, passing amount of 0.08mm sieve satisfied the requirement of KS except one sample. Grain distribution of most crushed sand is estimated $54.26\%$. But 6 crushed sand sample did not meet the requirement of KS. Fineness modulus and grading are varied from manufacturing region. 18 samples of crushed sand among 29 samples deviated the minimum level of standard grading range by KS. Therefore, improvement of grain properties of crushed sand is urgently needed to manufacture better crushed sand.

• Wind and Structures
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• v.36 no.2
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• pp.75-90
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• 2023

Turbulent wind flow over hilly terrains has been extensively investigated in the scientific literature and main findings have been included in technical standards. In particular, turbulent wind flow over nominally two-dimensional hills is often adopted as a benchmark to investigate wind turbine siting, estimate wind loading, and dispersion of particles transported by the wind, such as atmospheric pollutants, wind-driven rain, windblown snow. Windblown sand transport affects human-built structures and natural ecosystems in sandy desert and coastal regions, such as transport infrastructures and coastal sand dunes. Windblown sand transport taking place around any kind of obstacle is rarely in equilibrium conditions. As a result, the modelling of windblown sand transport over complex orographies is fundamental, even if seldomly investigated. In this study, the authors present a wind-sand tunnel test campaign carried out on a nominally two-dimensional sinusoidal hill. A first test is carried out on a flat sand fetch without any obstacle to assess sand transport in open field conditions. Then, a second test is carried out on the hill model to assess the sand flux overcoming the hill and the morphodynamic evolution of the sand sedimenting over its upwind slope. Finally, obtained results are condensed into a dimensionless parameter describing its sedimentation capability and compared with values resulting from other nominally two-dimensional obstacles from the literature.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.76-82
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• 1997

Recently as the development of a large-scale ocean structure or ocean is in progress, the importance of underwater concrete construction came to the fore. However, a problem with this underwater concrete construction is the segregation of cement and aggregate occurs when concrete is poured into the underwater. However, recently as an adhesiveness of the constituents of fresh concrete is increased even in our country, antiwashout concrete admixture were developed. The antiwashout concrete admixture can reduce the segregation significantly. Although this antiwashout underwater concrete is superior to the traditional underwater concrete in terms of durability, watertightness, stability, etc. But it is still unsatisfied due to the lack of criterion or construction experiences. Furthermore, because of an insufficiency of natural aggregate, the development of replacing aggregate came to be necessary. Accordingly, the purpose of this study is to investigate the feasibility of sea sand as a replacing aggregate and the characteristic change of antiwashout underwater concrete using river sand, sea sand, and blended sand (river sand:sea sand=3:7) through experimental researches.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.99-100
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• 2012

This study tried to present the appropriate replacement ratio of the recycled sand through the properties of the ternary system inorganic composite mortar according to replacement ratio change of the recycled sand about the natural sand through test verification. The flowing and compressive strength was degraded as the replacement ratio of the experimental result recycled sand increased. The appropriate replacement ratio of the recycled sand according to it was shown up less than 15%.

• Membrane and Water Treatment
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• v.12 no.2
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• pp.51-58
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• 2021

The natural weathered sand of basalt (WSB) has been used for the removal of cadmium from aqueous solution. The influence of various parameters i.e., contact time, pH, weathered sand of basalt dosage, particle size of the weathered sand of basalt, temperature and initial cadmium concentration were analyzed. Cadmium adsorption kinetics was well described by the pseudo second order model. Adsorption equilibrium for cadmium was properly well fitted to Langmuir isotherm model with maximum adsorption capacity 0.50 mg/g. Compared with the other experimental results using various kinds of adsorbents at a low concentration (1.0 mg/L or so) similar to that of this study, the cadmium removal efficiency using weathered sand of basalt was higher. It has been demonstrated that weathered sand of basalt has a available alternative adsorbent for cadmium when its initial concentration is low.

• Geomechanics and Engineering
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• v.29 no.5
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• pp.535-548
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• 2022

Recently, the construction industry has focused on eco-friendly materials instead of traditional materials due to their harmful effects on the environment. To this end, biopolymers are among proper choices to improve the geotechnical behavior of problematic soils. In the current study, serish biopolymer is introduced as a new binder for the purpose of sand improvement. Serish is a natural polysaccharide extracted from the roots of Eremurus plant, which mainly contains inulins. The effect of serish biopolymer on sand treatment has been investigated through performing unconfined compressive strength (UCS), California bearing ratio (CBR), as well as wind erosion tests. The results demonstrated that serish increased the compressive strength of dune sand in both terms of UCS and CBR. Also, wind erosion resistance of the sand was considerably improved as a result of treatment with serish biopolymer. A microstructural study was also conducted via SEM images; it can be seen that serish coated the sand particles and formed a strong network.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.13 no.2
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• pp.95-104
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• 2010

The purpose of this study is to analyze the correlation between physical stream characteristics and bed materials in natural rivers. Accordingly, four natural rivers were selected reference streams, they were Nam river, Sumjin River, Naesung River and Han River. Grain size distributions of bed materials were gravels, cobbles and boulders in Han river and Nam river, were sand, gravels, cobbles and boulders in Sumjin river and were sand in Naesung river. Four reference streams were divided into each two reference reaches (straight and bend) by plan and profile characteristics of naturally meandering stream. Therefore various reference reaches were chosen in the aspect of physical stream characteristics and grain size distributions. The results investigated and analyzed are as follows. The streams that grain sizes distributions of river bed materials were coarse were stable because they had variety of bed slope without sediment deposition, and then the riffles frequency and the physical characteristics were various. Also, velocitydepth regime were various in four kinds, and the response parts for water level change were small, so that channel flow status were stable and excellent condition. On the other hand, sand river that grain sizes distributions of river bed materials were fine had not the variety of parameters as velocity-depth regimes, sediment deposition, channel flow status and riffles frequency, so that the physical stream characteristics were not various.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.647-652
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• 1999

The purpose of this study is to find the bond properties of deformed bars in hign-strength concrete by experimental and analytical method. In this study the following variables were adopted, i.e. (1) the compressive strength of concrete : 270, 400 and 600kg/$\textrm{cm}^2$ (2) the corrosion the bars : corroded and normal bars (3) the mixing ratio of natural and smashed fine aggregate : 7 : 3 and 5 : 5 (natural sand : smashed sand) For analytical method, the finite element analysis is performed. And the Pull-out test is performed as the experimental method.

• Structural Engineering and Mechanics
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• v.53 no.6
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• pp.1241-1251
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• 2015

Faced with the growing needs of material resources and requirements of environmental protection for achieving sustainable development, it has become necessary to study and investigate all possibilities of exploring crushed and dune sand, reusing industrial wastes and by-product, and also applying new technologies including sand concrete which can replace the conventional concretes in certain structures to surmount the deficit on construction materials, conserve natural resources, lessen the burden of pollutants to protect the environment and reduce the consumption of energy sources. This experimental study is a part of development and valorization of local materials project in Skikda region (East of Algeria). It aims at studying the effects of partial replacement of sand with marble waste as fines on several fresh and hardened properties of sand concrete in order to reuse these wastes in the concrete manufacturing, resolve the environmental problems caused by them and find another source of construction materials. To achieve these objectives, an experimental program has been carried out; it was consisted to incorporate different percentages of marble waste fines (2, 4, 6, 8, 10 and 12%) in the formulations of sand concrete and study the development of several mechanical and rheological properties. We are also trying to find the optimal percentage of marble waste fine replaced in sand concrete that makes the strength of the concrete maximum. Obtained results showed that marble waste fines improve the properties of sand concrete and can be used as an additive material in sand concrete formulation.