• Korean Journal of Soil Science and Fertilizer
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• v.46 no.5
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• pp.379-385
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• 2013

Although sorghum residue production was estimated to be $8{\sim}10Mg\;ha^{-1}$, most sorghum straw was used to be burnt or removed after harvest. This experiment was conducted to evaluate the effect of the incorporation of manured sorghum residues on soil physical properties from 2010 to 2012 in the converted paddy field. Five treatment with 3 replication consisted of control, inorganic fertilizer (NPK), manured residues, sorghum stover and sawdust manure. The incorporation level of organic source was $10Mg\;ha^{-1}$ without inorganic fertilizer NPK. The investigated physical parameters were bulk density (BD), porosity, water stability aggregate (WSA), water infiltration rater (WIR), penetration resistance (PR) and soil water retention characteristics (WRC) with soil depth. The incorporation of manured sorghum residues improved WIR significantly over inorganic fertilizer (NPK), sorghum residues and sawdust manure. The BD by incorporating with manured residues on sorghum was reduced significantly with crop residue over plot of NPK and sawdust. Significant increase in WSA was observed with stubble incorporation alone or manured sorghum residues. Soil WRC were significantly enhanced with manured sorghum residue incorporated without NPK. The average PR at 0~15 cm was 0.54 MPa for manured sorghum residues. For sawdust manure plot it was 0.42 MPa, for Sawdust manure plot 0.39 MPa and for NPK plot 0.54 MPa.

• International Journal of Highway Engineering
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• v.17 no.4
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• pp.53-61
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• 2015

PURPOSES : The objective of this study is to evaluate the SDAR (solvent deasphaltene residue), which is obtained from the solvent deasphalting (SDA) process, as a pavement material. METHODS : The physical properties of the SDAR were evaluated based on its chemical composition, and asphalt mixtures with the SDAR were fabricated and used for the evaluation of mechanical properties. Firstly, the chemical composition of SARA (saturate, aromatic, resin and asphaltene) was analyzed using the TLC-FID (thin-layer chromatography-flame ionization detector). Moreover, the basic material properties of the asphalt binder with the SDAR were evaluated by the penetration test, softening point test, ductility test, and PG (performance grade) grade test. The rheological properties of the asphalt binder with the SDAR were evaluated by the dynamic shear modulus ($G^*$) obtained using the time-temperature superposition (TTS) principle. Secondly, the mechanical properties of the asphalt mixtures with the SDAR were evaluated. The compactibility was evaluated using the gyratory compacter. Moreover, the tensile strength ratio (TSR) was used for evaluating the moisture susceptibility of the asphalt mixtures (i.e., susceptibility to pothole damage). The dynamic modulus $E^*$, which is a fundamental property of the asphalt mixture, obtained at different temperatures and loading cycles, was used to evaluate the mechanical properties of the asphalt mixtures. RESULTS AND CONCLUSION : The SDAR shows stiffer and more brittle behavior than the conventional asphalt binder. As the application of the SDAR directly in the field may cause early failures, such as cracks on pavements, it should be applied with modifiers that can favorably modify the brittleness property of the SDAR. Therefore, if appropriate additives are applied on the SDAR, it can be used as a pavement material because of its low cost and strong resistance to rutting.

• The Plant Pathology Journal
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• v.33 no.1
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• pp.95-100
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• 2017

Fungicide-resistant Alternaria alternata impede the practical control of the Alternaria diseases in crop fields. This study aimed to investigate cytological fungicide resistance mechanisms of A. alternata against dicarboximide fungicide iprodione. A. alternata isolated from cactus brown spot was cultured on potato-dextrose agar (PDA) with or without iprodione, and the fungal cultures with different growth characteristics from no, initial and full growth were observed by light and electron microscopy. Mycelia began to grow from one day after incubation (DAI) and continued to be in full growth (control-growth, Con-G) on PDA without fungicide, while on PDA with iprodione, no fungal growth (iprodione-no growth, Ipr-N) occurred for the first 3 DAI, but once the initial growth (iprodione-initial growth, Ipr-I) began at 4-5 DAI, the colonies grew and expanded continuously to be in full growth (iprodione-growth, Ipr-G), suggesting Ipr-I may be a turning moment of the morphogenetic changes resisting fungicidal toxicity. Con-G formed multicellular conidia with cell walls and septa and intact dense cytoplasm. In Ipr-N, fungal sporulation was inhibited by forming mostly undeveloped unicellular conidia with degraded and necrotic cytoplasm. However, in Ipr-I, conspicuous cellular changes occurred during sporulation by forming multicellular conidia with double layered (thickened) cell walls and accumulation of proliferated lipid bodies in the conidial cytoplasm, which may inhibit the penetration of the fungicide into conidial cells, reducing fungicide-associated toxicity, and may be utilized as energy and nutritional sources, respectively, for the further fungal growth to form mature colonies as in Ipr-G that formed multicellular conidia with cell walls and intact cytoplasm with lipid bodies as in Con-G.

• Macromolecular Research
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• v.17 no.5
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• pp.332-338
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• 2009

Rheological behavior of natural hydrogel produced from seeds of three Salvia spp. (S. miltiorrhiza (SM), S. sclarea (SS), S. viridis (SV)) was investigated by using a Rheometer equipped with a cone and plate geometry measuring system under never-dried condition. Different chemical contents of such hydrogels give significant effects on their rheological properties. Because of incomplete penetration of water inside the hydrogels after drying before-dried hydrogels were used for rheological analysis. To know molecular interactions which predominated in the gel formation, some constituents were externally added to the 1.0% (w/w) hydrogel. Addition of urea to disrupt hydrogen bonds reduced 3.4-67% viscosity of the untreated hydrogels and changed viscoelastic properties from gel to liquid-like behavior. Neutral salts added to the hydrogel solution at 0.1 M also lowered the viscosity in a manner related with increase in size of cations and temperature. Changing from gel state to liquid-like state was also easily confirmed by oscillation measurement (storage, G', and loss, G", modulii) typically observed in the cases of potassium sulfate and potassium thiocyanate. Influence of pH variation on the viscosity explained that weak alkaline condition (pH 8-9) creates a higher resistance to flow due to increasingly electrostatic repulsions between negative charges ($COO^-$) Importance of calcium bridges was also demonstrated by recovery of viscosity of the hydrogels by addition of calcium after acidification. The summarized results indicate that electrostatic repulsion is a major contributor for production of hydrogel structure.

• Journal of the Korean Geosynthetics Society
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• v.13 no.1
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• pp.53-61
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• 2014

Sea gives us a lot of benefits and one of them is a role of transporting goods easily by ship. Accordingly the industrial area or the container yard is constructed either on the low sea or near the sea. Sea dredging ground is made by pumping them using dredge pump to the inside of embankment after dredging undersea soils. The dredging ground after pumping is in the slurry state but as time goes, consolidation by the own weight happens and evaporation happens at the surface of dredging ground. The evaporation causes the crest layer in the upper side of dredging ground. Under the crest layer there is still a soil of slurry state which has just little bearing resistance. This kind of characteristics makes it difficult to get a exact bearing capacity using the equations proposed until now. In this study we have performed simultaneously both the field loading tests and the cone penetration tests on the sea dredging ground. From the result of field tests, new experimental equation for the ultimate bearing capacity has been proposed. If we use the new equation, it is believed that some design of sea dredging ground could be more accurate.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.3
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• pp.243-249
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• 2016

The present work is for an evaluation of resistance to corrosion in steel coated with cementitious repair material, so that 3 cases of steel plate(Normal, Welding, Welding & coating case) are subjected to ICM(Impressed Current Method) for acceleration of corrosion for 7days. Tested and estimated corrosion ratio through Faraday's Law are compared, and the related flexural strength are evaluated. In Normal and Welding cases, similar level of corrosion ratio(70%) is evaluated, however only 17% level of corrosion ratio is evaluated in the Welding & coating case, which indicates that cementitious repair material is effective to anti-corrosion due to a block of chloride penetration. The flexural test results are consistent with those in accelerated corrosion test, which shows a significant flexural strength in Welding & coating case by 3.4times greater than the others. The cementitious material repair coating is evaluated to be effective to anti-corrosion in welding of steel plate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.429-438
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• 2018

Cone and T-bar penetrometers have been frequently used to estimate the undrained shear strength of clay. For small-size model tests, miniature penetrometers should be used but their correlation factors have not been well published. In this study, a testing setup was developed to derive empirical factors of the miniature cone and T-bar penetrometers. A 350mm-diameter chamber and kaolin clay were utilized to prepare soil specimens consolidated under four different pre-consolidation pressures controlling undrained shear strength. Two miniature cones with two diameters of 10-mm and 16-mm and a T-bar penetrometer with 10-mm diameter were used to investigate boundary effect, penetration rate effect, and diameter and shape effect. Unconsolidated-undrained triaxial tests were carried out with samples taken from the specimens to measure undrained shear strength. Finally, empirical factors for the penetrometers were constructed to correlate tip resistance to undrained shear strength.

• International Journal of Highway Engineering
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• v.12 no.3
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• pp.113-119
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• 2010

This study presents experimental findings on the performance of cement concrete pavement incorporating mineral admixtures such as ground granulated blastfurnace slag and silica fume. Flexural strength, compressive strength, charge passed, diffusion coefficient of chloride ions and initial surface absorption of cement concrete pavement incorporating mineral admixtures were periodically measured and the corresponding results were compared to those of plain concrete pavement. As a result, strength behaviors of concrete pavement were dependent on the types of mineral admixtures. However, it was true that incorporation of silica fume had a beneficial effect on compressive strength development. Furthermore, the application of mineral admixtures led to a lower diffusion coefficient of chloride ions compared to plain concrete pavement. Based on the experimental results, the present study would be helpful to design high-performance cement concrete pavement.

• The Journal of Engineering Geology
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• v.27 no.3
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• pp.191-205
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• 2017

We use small-scale modelling to estimate the impact ofrce of debris flows on erosion control dams (ECD) and ring nets. The results indicate that the viscoelastic debris flows produced impact forces of 4.14, 3.66, 1.66 kN from the bottom to the top of the ECD. Ring net tests produced a similar trend with generally smaller impact forces (2.28, 1.95, and 1.49 kN). Numerical analysis showed that the weight of the ECD (e.g., concrete retaining walls) provided resistance against the debris flow, whereas deformation of the ring net by elastic-elongation and aggregate penetration reduced the impact force by up to 45% compared with that of the ECD.

• International Journal of Highway Engineering
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• v.20 no.2
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• pp.9-17
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• 2018

PURPOSES : The frequency and severity of natural disasters such as torrential rain or typhoons have become increasingly significant worldwide. Events such as summer typhoons and localized torrential downpour can cause severe damages to a residential area and road networks, resulting in serious harm to the daily lives of people, especially in rural areas by isolating residents from road networks. An immediate and emergency repair technology for the collapsed road networks is urgently needed. This study introduces a new technology to repair road bases or slopes. METHODS : The development of new technology for emergency and permanent repair consists of first, packing of cement paste-coated gravel, second, combining appropriate equipment, and third, conducting a field applicability test. In this research, the compressive strength of cement pastecoated gravel, gravel-netting concrete properties, and packing efficiency were determined, and a full scale field mock-up test was carried out. RESULTS : The compressive strength of the cement paste-coated gravel concrete satisfied the required limit for road base of 5 MPa after 7 days. With appropriate netting materials and packing size, gravel-netting concrete was successful up to a slope of 1:1.5. The full scale field mock-up test showed efficiency in the field and penetration resistance performance. CONCLUSIONS : The new technology of emergency and permanent repair for damaged road bases and slopes, introduced in this study, showed satisfactory performance. The technology is expected to be applied in the field when construction procedures and quality specifications are made.