• Korean Journal of Soil Science and Fertilizer
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• v.42 no.4
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• pp.239-248
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• 2009

In this investigation, we observed surface morphology and porosity of a macroporous adsorbent made of Na-bentonite and Ca-bentonite as structure formation materials and grounded waste paper as macropore forming material for the development of a permeable reactive barrier to remove heavy metals in groundwater. Therefore, we selected minerals having higher cation exchange capacity among 2:1 clay minerals and other industrial minerals because sintering can significantly influence cation exchange capacity, resulting in drastic decrease in removal of heavy metals. The results showed that the increasing sintering temperature drastically decreased CEC by less than 10 % of the indigenous CEC carried by the selected minerals. One axial compressibility test results showed that the highest value was obtained from 5% newspaper waste pulp for both structure formation materials of Na-bentonite and Ca-bentonite although there were not much difference in bulk density among treatments. The pore formation influenced by sintering temperature and period contributes removal of heavy metals passing through the sintered macroporous media having different water retention capacity.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.421-426
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• 2017

In this paper, the effect of freezing-thawing action on the dynamic modulus and porosity was examined by ultrasonic pulse velocity (UPV) measurement. UPV was measured every 30 cycles during the freezing-thawing test, and dynamic modulus and porosity of cement mortar were calculated by relationship among UPV, porosity and dynamic modulus. Porosity analysis was also performed to compare with calculated porosity by mercury intrusion porosimetry (MIP). From the test, it was found that dynamic modulus of cement mortar was decreased 13% after 300 cycles. The calculated porosity was increased about 30% compared with the initial porosity before freezing-thawing action. The calculated porosity showed similar increase tendency with the porosity measured by MIP. So, it can be concluded that the porosity change of cementitious materials by freezing-thawing action can be predicted by UPV measurement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.143-149
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• 2020

The purpose of this study is to manufacture a variable density - hybrid lattice structure control by filling the pore of the metal addictive manufactured lattice structure with lightweight reactive acrylic compounds(RAC). To apply the variable density - hybrid lattice structure to the construction industry, the enhancing adhesion - reactive acrylic compounds(EA-RAC) which increased the adhesion strength was manufactured by adding ordinary portland cement to the RAC. Finally, the EA-RAC was filled into the lattice structure to test the specific density, water absorption, and adhesion strength of the variable density - hybrid lattice structure. The results were obtained with density controllable, water absorption less than 1.0%, and 1-day bonding strength of 1.78 MPa to 1.98 MPa.

• The Journal of Engineering Geology
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• v.26 no.3
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• pp.339-352
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• 2016

The best way of investigating the physical and mechanical properties of subsurface materials is the combined interpretation of data from borehole geophysical surveys and geotechnical experiments with rock samples. In this study two surface seismic surveys with refraction and surface-wave method are alternatively conducted for downhole seismic surveys in test site for geological field trip in Jeungpyung, Chungbuk. P- and S-wave velocity structures are delineated by refraction and MASW (multichannel analysis of shear waves) methods, respectively. Possion's ratio section, reconstructed from P- and S-wave velocities, is correlated to the outcrop geological features consisting of reddish sedimentary rock, gray volcanic rock, and joints/fractures. In addition, rock samples representative for reddish sedimentary and gray volcanic features are geotechnically analyzed to provide physical, mechanical properties, and elastic modulus. Dynamic elastic moduli estimated from geophysical data is found to be higher than the one from geotechnical data. Reddish sedimentary rock characterized with low porosity and moisture content corresponds to the zone of low electrical resistivities and their small variations in the resistivity sections between the rainy and dry days. This trend suggests that the weathered gray volcanic rock and the nearby fractures with higher low porosity and moisture content are interpreted to be good carrier especially in rainy season.

• Tunnel and Underground Space
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• v.15 no.3 s.56
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• pp.223-227
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• 2005

The physical and mechanical properties of volcanic glass, which is distributed in the Samho area, South Korea were studied. Laboratory rock tests were carried out in order to obtain the various properties of rocks. Specific gravity, water content, absorption, porosity and wave velocity were measured for the physical properties. Uniaxial and triaxial compressive tests, Brazilian test and point load test were also performed for the mechanical properties. The tests of volcanic glass revealed that the apparent specific gravity, water content and absorption were 2.28, $1.67\%$ and $1.72\%$, respectively. Porosity $(3.87\%)$ was lower, whereas P-wave velocity (5330m/s) and S-wave velocity (2980 m/s) were relatively higher. Brazilian tensile strength ot 7.2MPa, and point load strength of 2.6MPa were among the mechanical properties of the rock. Uniaxial compressive strength (62.4MPa) estimated ken point load strength was very closed to the value (66.0MPa) from the uniaxial compressive test. Young's modulus and Poisson's ratio were E=43.2 GPa and v=0.28, respectively. Drawing the tangent line to Mohr-Coulomb failure criterion showed the cohesion of 20.1MPa and internal fraction angle of $28.6^{\circ}$.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.3
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• pp.253-259
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• 2021

Plastic wastes generated from household waste are separated by mixed discharge with foreign substances, and recycling is relatively low. In this study, the effect of the ratio and content of mixed plastic waste coarse aggregate(MPWCA)s and mixed plastic waste fine aggregate(MPWFA)s filled with blast furnace slag fine powder on the slump and compressive strength of concrete was evaluated experimentally. The MPWCAs were found to have a similar fineness modulus, but have a single particle size distribution with a smaller particle size compared to coarse aggregates. However, the MPWFAs were found to have a single particle size distribution with a larger fineness modulus and particle size compared to fine aggregates. Meanwhile, the effect of improving the density and filling pores by the blast furnace slag fine power was found to be greater in the MPWFA compared to the MPWCA. As the amount of the mixed plastic waste aggregate(MPWA)s increased, the slump and compressive strength of concrete decreased. In particular, the lower the slump and compressive strength of concrete was found to decrease the greater the amount of MPWFA than MPWCA when the amount of MPWA was the same. This is because of the entrapped air and voids formed under the angular- and ROD-shaped aggregates among the MPWFAs. On the other hand, the addition of the admixture and the increase in the unit amount of cement were found to be effective in improving the compressive strength of the concrete with MPWAs.

• Journal of the Korean Wood Science and Technology
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• v.36 no.1
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• pp.54-60
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• 2008

Sound absorption coefficients of oak (Quercus mongolica) wood and oak mushroom bed log were measured by the two microphone transfer function method and anatomical features of oak mushroom bed log examined by stereo scope and SEM observations. The sound absorption coefficients of oak mushroom bed log seemed to be higher than those of normal oak wood specimen over all estimated frequency range. Especially, in the frequency range of 2 to 6 kHz, they were about 2~3 times higher than those of normal wood specimen. Due to fungi degradation, the specific gravity of oak mushroom bed log decreased about 70% than that of normal wood. For oak mushroom bed log, abundant pores occurred on the radial, tangential and cross sectional surface and it was considered that the pores behaved as a sound absorbing pore.

• Journal of the Korean GEO-environmental Society
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• v.16 no.11
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• pp.29-37
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• 2015

Non-excavation method is needed to secure the stability of existing structures during construction. Therefore, prediction of ground settlement is essential. Causes of settlement when using steel pipe indentation method are leading pipe-steel pipe gap, excessive excavation and soil-steel pipe friction etc. Also they are similar to the causes of settlement when using Shield TBM during construction. In this study, ground settlement during steel pipe indentation is predicted by the Gap Parameter Method and Volume Loss Method which are kinds of Shield TBM prediction Method. and compared with those of prediction methods by conducting field test. As a result, Volume Loss Prediction Method is the most similar to the field tests. However, It is needed to additional studies, such as decision of the factors and adaptability for total settlement predictions of non-excavation method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4A
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• pp.303-309
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• 2011

Laminated rubber bearing is the most commonly used device for seismic base isolation of bridge structures. It is important to know performance and behavior characteristics of the laminated rubber bearings. The main evaluation factors of the rubber bearing are classified as compressive, shear and tensile behavior characteristics. The reference data of compressive and shear characteristics are rich, but the reference data of tensile characteristics is scarce. In this study, tensile test results of the rubber bearing with variation of shape factor and shear deformation are investigated for mechanical property. When tensile deformation in normal condition is increasing, tensile cycle behavior curve becomes non-linear and tensile breaking point is 300%. On the other hand, tensile breaking point is shear deformation condition is about 40%. Furthermore, when shape factor is lower, tensile breaking point is decrease. This results mean that tensile breaking point is decreased in triaxial tensile deformation because of cracks caused by internal void of the rubber bearings. This experimental data can be used as the reference data of tensile characteristics for designing seismic isolation of structures.

• Journal of Korean Society of Forest Science
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• v.83 no.4
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• pp.473-479
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• 1994

This study was carried out to get the basic data for obtaining water resources continuously. Water storage of forest land was estimated by effective water storage based on classifying soil pore. The results were summarized as follows ; 1. Percentage of coarse pores were in the order : Forest>Bare land>Grasses. As soil depth increased, total pores, coarse pores, and maximum water content were decreased, while fine pores increased. 2. Soil pore percentage and physical properties of surface layer(0~20cm) were significantly different among forest floor conditions. However, there were no difference in soil pore percentage and physical properties in 20~40cm and 40~60cm according to forest floor conditions. In the same plot, on the other hand, soil pore percentage and physical properties were significantly different between surface layer(0~20cm) and 20~40cm, but there were no differences between 20~40cm and 40~60cm. 3. Effective water storage was highly correlated with coarse pore in all plots. 4. The model for water storage capacity of each forest floor condition expressed by effective water storage was produced using coarse pores and soil depth.