• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.63-71
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• 2010

This study was performed to evaluate the planting properties and root potential of planting block with mixing seeding of herbaceous plants and cool-season grasses in CSG blocks manufactured by cemented sand and materials (CSG) in order to develop environmentally friendly CSG block applied revegetation. Five types of CSG mix designs with cement contents were determined, and the mechanical properties of CSG materials were studied experimentally. To analyze growth properties of plants within CSG block, germination ratio, visual cover, plant height and root potential were measured in four weeks and eight weeks after seeding. The germination regardless mixture seeding of plants and CSG mixproportions started within 4 ~ 7 days after seeding and the germination ratio were in the range of 60 ~ 65 %. The visual cover of kinds of plants evaluated by visual rating system were in the range of 6 ~ 8 in case of seeding the species of cool-season grasses and were in the range of 4 ~ 6 in case of seeding the species of herbaceous plants in four weeks after seeding. The root potential of CSG block with the species of cool-season grasses and herbaceous plants were in the range of $5.7{\times}10^{-3}{\sim}7.7{\times}10^{-3}$ MPa and $2.3{\times}10^{-3}{\sim}6.7{\times}10^{-3}$ MPa in eight weeks after seeding, respectively.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.27-33
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• 2011

This study is a preliminary investigation into the development of a construction method that will protect a reservoir even during over flows caused by severe flooding. Through hydraulic modeling tests, the destructive phenomena caused by spillway-junction scour during reservoir overflow were modeled, and the effects on the embankment during such an overflow and the spillway-junction movements are discussed. The reservoir destruction model used the Tanbu reservoir, located in Gangwondo Chuncheon-si Namsanmyeon (H＝22 m, L＝115 m), as the model reservoir and created an embankment with a 1/60 ratio. We review the spillway-junction safety factor during overflow and embankment movement following reinforcement measures for three different cases: no reinforcement, cemented sand and gravel (CSG) reinforcement and water-blocking sheet reinforcement. The results of this study confirmed that when the spillway-junction is exposed to soil, it is very vulnerable to overflow and that a water-blocking sheet or CSG reinforcement are very effective measures in preventing embankment destruction in the long-term period.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.51-59
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• 2010

The cemented sand and gravel (CSG) method is a construction technique that adds cement and water to rock-like materials, such as rivered gravel or excavation muck which that can be obtained easily at areas adjacent to dam sites. This study was performed to evaluate the unconfined compressive strength properties and freezing and thawing resistance of CSG materials with unit cement content. The three types of CSG-80, CSG-100 and CSG-120 with cement content were designed to evaluate the optimum water content, dry density, strength, stress-strain, micro structure and durability factor. As the results, the optimum water content ratio with cement content showed almost similar tendency, and the unconfined compressive strength and dry density increased as cement content increases. The strength ratio of 7 days for 28 days were in the range of 55~61 % and the strain ratio in stress-strain curve were in the range of 0.8~1.6 % nearby maximum strength in 28 days. It is expected that this study will contribute to increasing application of CSG method as well as to increasing the utilizing of CSG materials as a environmentally friendly CSG method.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.417-426
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• 2019

Gangue filling in the goaf is an effective measure to control the surface subsidence. However, due to the obvious deformation of gangue compression, the filling effect deserves to be further studied. To this end, the deformation of coal gangue filling in the goaf is analyzed by theoretical analysis, large-scale crushed rock compression test, and field investigation. Through the compression test of crushed rock, the deformation behaviour characteristics and energy dissipation characteristics is obtained and analysed. The influencing factors of gangue filling and predicted amount of main deformation are summarized. Besides, the predicted equation and filling subsidence coefficients of gangue are obtained. The gangue filling effect was monitored by the movement observation of surface rock. Gangue filling can support the roof of the goaf, effectively control the surface subsidence with little influence on the ground villages. The premeter and equations of the main deformation in the gangue filling are verified, and the subsidence coefficient is further reduced by adding cemented material or fine sand. This paper provides a practical and theoretical reference for further development of gangue filling.

• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.1
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• pp.33-40
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• 2010

The cemented sand and gravel (CSG) method is a construction technique that adds cement and water to rock-like materials, such as rivered gravel or excavation muck which that can be obtained easily at areas adjacent to dam sites. This study was performed to evaluate the planting properties of herbaceous plant and cool-season grass in CSG blocks that were manufactured by using CSG materials to develop environmentally friendly CSG method. The two types of CSG-0 without cement and CSG-100 with $100\;kg/m^3$ of cement were designed to evaluate compaction, unconfined compressive strength and growth of plants with cement content by using modified E compaction. To analyze growth properties of plants, germination ratio, visual cover, plant height and root length were measured in 4 weeks and 8 weeks after sowing. As the results, the germination regardless kinds of plants started within 5~7days and the germination ratio were in the range of 50~60 %. The visual cover of kinds of plants by visual rating system were in the range of 7~8 and the visual cover of tall fescue and perennial ryegrass was higher than that of lespedeza cuneata. The plant height and root length for tall fescue and perennial ryegrass in 8 weeks after sowing were in the range of 22~26 cm, 12~15 cm and 4~6 cm, 3~5 cm, respectively.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.95-104
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• 2013

Recently, application of CSG is increasing in various design construction projects. At the initial stage of cementation CSG materials show the same mechanical characteristics as soil, however, as the cementation process develops, CSG materials gradually reveal material characteristics of concrete. The hardened CSG manifests elastic behavior such as maximum strength at small strain range and rapid brittle failure. In this research, PVA fiber stiffeners were used in order to: (1) reduce such brittle behavioral characteristics; (2) improve the relatively weak tension performance of CSG materials. The binding strength between the bed materials and fiber prevents rapid brittle failure and increases tensional strength of fiber reinforced CSG materials.Test results show that fiber reinforcement alone could induce the stress-strain characteristics of CSG materials from brittle failure to ductile failure and also increase the residual strength.

• The Journal of Korean Academy of Prosthodontics
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• v.52 no.2
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• pp.113-120
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• 2014

This study will evaluate the effectiveness of various pretreatments when fiber-reinforced composite (FRC) post is bonded to endodontically treated tooth with resin cement. Materials and methods: Canal shaping of FRC post (DT Light post, Size 3, Bisco Inc., Schaumburg, IL, USA) was performed on endodontically treated premolars at 1.5 cm from CEJ. Samples were divided into 6 groups of surface treatment after conventional washing and drying to the canal. Total of 24 FRC posts were randomly divided into 6 groups of surface treatment as follows: Group C: control - no surface treatment, Group A: airborne-particle abrasion (Cojet sand, 3M ESPE), Group S: silanization (Bis-silane, Bisco Inc.), Group M: universal primer (Monobond-plus primer, Ivoclar Vivadent Inc.), Group AS: silanization after airborne-particle abrasion, Group AM: universal primer treatment after airborne-particle abrasion. Pretreated fiber posts were cemented with resin-based luting material and photo-polymerized and cut to the thickness of 1 mm. Push-out test using a universal testing machine was performed. Bonding failure strength of post dislodgement was measured and the type of bonding failure was classified. Data were analyzed with Kruskal-Wallis test and multiple comparison groups were performed using Tukey HSD value of rank test (${\alpha}=0.05$). Results: Group AS showed significantly highest bonding strength. Group S, group AM, group A, and group M showed lower bonding strength in order. The control group showed the lowest bonding strength. Conclusion: Surface treatment with silane showed to be the most effective of the surface pretreatment methods for cementation of FRC post. Surface treatment with universal primer showed no significant difference compared with no surface treatment group as for bonding strength.