• Geomechanics and Engineering
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• v.7 no.5
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• pp.539-552
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• 2014

A simplified probability-based design charts for stone column-improved ground have been presented based on the unit cell approach. The undrained cohesion ($c_u$) and coefficient of radial consolidation ($c_r$) of the soft soil are taken as the most predominant random variables. The design charts are developed to estimate the diameter of the stone column or the spacing between the stone columns by employing a factored design value of $c_r$ and $c_u$ so as to satisfy a specific probability level of the target degree of consolidation and/or a target safe load that needs to be achieved in a specified timeframe. The design charts can be used by the practicing engineers to design the stone column-improved ground by considering consolidation and /or bearing capacity of the improved ground.

• The Journal of Korean Academy of Prosthodontics
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• v.33 no.3
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• pp.569-583
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• 1995

Disinfection of dental impressions are necessary due to contamination with patient’s saliva and blood, which is a potential for cross-infection. The purpose of this study was to evaluate the effects of disinfection of four hydrophilic rubber impression materials with three disinfecting solutions, on the dimensional stability and surface hardness of improved stone casts. Three hydrophilic vinyl polysiloxane impression materials(Express, Reprosil, Exafine) and one polyether impression material(Impregum-F) were mixed according to the manufacturer’s directions and impressions were made on a ADA specification No. 19 stainless-steeldie. On removal of the impressions, each impression was immersed in one of the disinfectants(Banicide, Potadine, Clorox) for 10 minutes. After disinfection, type IV improved stone. casts were poured. On this cast, the linear dimension and surface hardness were measuredusing a Measurescope(Nikon, Japan) and a Barcol hardness tester(Barber, Colman Co U. S. A). The results were as follows : 1. The improved stone casts from disinfected Reprosil and Impregum-F impression material did not show dimensional changes(P>0.01). Those from disinfected Express and Exafine impression material showed dimensional changes(P<0.01). The amount of shrinkage was not clinically significant. 2. The improved stone casts from disinfected Express impression material did not exhibit changes in surface hardness(P>0.01), but those from disinfected Reprosil, Exafine, Imp regnum-F impression material showed changes in surface hardness(P<0.01). 3. The dimensinal stability and surface hardness of the improved stone casts were satisfactory using Banicide on Express, all disinfectants used in this study on Reprosil, Potadin and Clorox on Exafine, Banicide and Clorox on Impregum-F. According to these results, immersion disinfection of hydrophilic rubber impression mate rials did not adversely affect the resultant casts. Nevertheless compatibility tests of impression materials and disinfectants should be done when disinfecting impressions.

• Journal of the Korean Geotechnical Society
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• v.26 no.12
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• pp.61-70
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• 2010

A series of shaking table tests were conducted to estimate the seismic performance of soft ground deposits improved by stone column. The amplification of acceleration, shear strain, and shear wave velocity were evaluated to compare the seismic response of unimproved ground deposits with that of improved ground deposits. From the test results, it was shown that the stone column can prevent large shear deformation in ground deposits. However, it was also found that the acceleration of improved ground deposits may be amplified more than that of unimproved ground deposits when it was subjected to short periodic seismic wave. The results suggest that it is necessary to perform the ground response analysis with model experiments for both unimproved and improved ground deposits to evaluate the effect of stone column on the seismic performance of improved ground deposits.

• Structural Engineering and Mechanics
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• v.50 no.1
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• pp.121-135
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• 2014

Stone masonry structures are widely used around the world, but they deteriorate easily, due to low shear strength capacity. Many techniques have been developed to increase the shear strength of stone masonry constructions. The aim of this experimental study was to investigate the performance of stone masonry walls strengthened by metal connectors as an alternative shear reinforcement technique. For this purpose, three new metal connector (clamp) types were developed. The shear strength of the walls was improved by applying these clamps to stone masonry walls. Ten stone masonry walls were structurally tested in diagonal compression. Various parameters regarding the in-plane behavior of strengthening stone masonry walls, including shear strength, failure modes, maximum drift, ductility, and shear modulus, were investigated. Experimentally obtained shear strengths were confirmed by empirical equations. The results of the study suggest that the new clamps developed for the study effectively increased the levels of shear strength and ductility of masonry constructions.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.3
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• pp.301-312
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• 1999

The purpose of this study was to compare the accuracy of currently used elastomeric impression materials for complete arch impression taking. Five elastomers (Impregum, Permlastic, Express, Extrude, Examix) and one Irreversible hydrocolloid (Aroma-fine) were tested. For each material, 5 impressions were made of stainless steel model to which five tapered posts were attached. Custom trays were used for polyether and polysulfide impression materials, and putty/wash two step technique was used for addition polyvinylsiloxane impression materials. Improved stone mod els were poured to all impressions. Accuracy of the materials was assessed by measuring ten distances on stone dies poured from impressions of the master model. All measurements for master and improved stone models were made with three dimensional measuring machine. The results were as follows 1. The dimensional accuracy of polyether, extrude, and examix were significantly superior to poly-sulfide, exress, and alginate in reproducing full arch mode (p<0.05) 2. There were no statistical differences in dimensional accuracy for full arch impression between polyether extrude and examix (p>0.05). 3. there were no statistical differences in dimensional accuracy between polysulfide, express, and alginate(p>0.05). 4. There were no statistical differences between addition polyvinyl siloxane materials (p>0.05) 5. There were no statistical differences between anterior-posterior and lateral dimensional changes of all impression materials (p>0.05).

• Journal of the Korean Geotechnical Society
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• v.28 no.4
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• pp.115-124
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• 2012

The responses of stone column-improved ground under seismic loading are investigated using a series of 1g shaking table tests. These tests show similar results to those of one dimensional numerical models for stone column-improved ground based on Baez's assumption on the soil and stone-column interaction. The experimental and numerical results show that the stone column can prevent large shear deformations incurred due to cyclic softening in clayey deposits, but they also show that the surface acceleration in the improved clayey deposits may amplify more than that in unimproved clayey deposits when subjected to short periodic seismic motions.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.715-723
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• 2017

This study investigates the properties of a high-performance cementitious composite with partial substitution of stone dust for fine aggregate. The relationship between the properties and particle size distribution was analyzed using several analytical models. Experiments were carried out to examine the flowability, rheology, and strength of cement mortars with different stone-dust replacement ratios of 0-30 wt.%. The results showed improved flowability, lower rheological parameters (yield stress and plastic viscosity), and improved strength as the amount of stone dust increased. These results are closely related to the packing density of the solid particles in the mortar. The effect was therefore estimated by introducing an optimum particle size distribution (PSD) model for maximum packing density. The PSD with a higher amount of stone dust was closer to the optimum PSD, and the optimization was quantified using RMSE. The improvement in the PSD by the stone dust was proven to affect the flowability, strength, and plastic viscosity based on several relevant analytical models. The reduction in yield stress is related to the increase of the average particle diameter when using stone dust.

• The Journal of the Korean dental association
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• v.38 no.8 s.375
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• pp.757-764
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• 2000

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.434-444
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• 2006

The stone column method is widely used in Europe as an alternative to conventional pile foundations. Several benefits of using the stone column method include sound performance, low cost, expediency of construction, and liquiefaction resistance, among others. Recently, geosynthetic-encased stone column approach has been developed to improve its' load carrying capacity through increasing confinement effect. Although such a concept has successfully applied in practice, fundamentals of the method have not been fully explored. This Paper Presents the results of an investigation on the loading carriying capacity of geogrid-encased stone column using a series of 2D finite element analyses. The results of the analyses indicated improved short- and long-term carrying capacity of the geogrid-encased stone column method over the conventional strone column method with no encasing.

• Fashion & Textile Research Journal
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• v.8 no.1
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• pp.129-133
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• 2006

To develope a high value-added fiber products which is useful in the human body physiology, the Macban stone was deposited on the PET fabric by sputtering and its effects were investigated. Then, a Macban stone target was prepared for sputtering treatment and treated on the PET fabric by RF sputtering process. After treatment, surface observation by SEM, far-infrared emissivity and emissive power, the fastness to washing and light, bacteriostatic rate, electrostatic, drape stiffness, and breaking strength of PET fabric were investigated. From these investigation, the following conclusions were obtained. 1) The Macban stone was able to deposit on the PET fabric, by the RF sputtering treatment which is eco-friendly dry textile finishing. 2) The far-infrared emissivity and emissive power of sputtered PET fabrics were increased. 3) When PET fabric was treated by sputtering with Macban stone, the amount of deposited Macban stone increased with increasing treatment time and it was deposited on the fabric surface firmly. 4) The bacteriostatic rate of sputtered PET fabrics was about 20%. 5) The electrostatic charge of fiber surface was reduced by sputtering. 6) The fastness washing to light of dyed fabric were improved by the deposition of Macban stone, but the breaking strength was not changed by sputtering. 7) The drape stiffness of sputtered PET fabrics increased with increasing treatment time.