• The korean journal of orthodontics
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• v.30 no.4 s.81
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• pp.453-465
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• 2000

The purpose of this study was to investigate the change of mechanical properties, surface topography and frictional force of various nickel titanium wires after recycling. Three types of nickel-titanium wires and one type of stainless steel wire were divided to three groups: as-received condition(T0:control group), treated in artificial saliva for four weeks(T1) and autoclaved after being treated in artificial saliva(T2). Some changes were observed for the selected mechanical properties in tensile test, surface topography by means of SEM and 3D profilogram, and frictional coefficient. The findings suggest that: 1. Nickel-titanium wires demonstrated no statistically significant differences in maximum tensile strength, elongation rate and modulus of elasticity, but stainless steel wire demonstrated statistically significant differences in maximum tensile strength, elongation rate and modulus of elasticity between the groups(p<0.05). 2. NiTi, Optimalloy, Stainless Steel wires demonstrated increased pitting and corrosion in SEM finding. 3. Recycled NiTi, Optimalloy and stainless steel wires demonstrated significantly greater surface roughness(Ra and Rq) through 3D profilogram when compared with the control wires(p<0.05), but Sentalloy didn't demonstrate significant difference. 4. Recycled NiTi, Optimalloy and stainless steel wires demonstrated significantly greater maximum frictional coefficient when compared with the control wires(p<0.05), but Sentalloy didn't demonstrate significant difference The changes of surface roughness and frictional coefficient in NiTi and Optimalloy had no clinical implication. Consequently recycled nickel titanium wires demonstrated no clinical problem in tensile properties, surface topography and frictional coefficient.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.3
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• pp.77-86
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• 2010

In this study, the model of the indirect wind suction waste sorting machine for characteristics of the screening of waste was studied using computational fluid dynamics and the drag coefficient for the model and the suction wind speed were obtained. The wind separator are developing by installing a cyclone air outlet to the suction blower impeller waste is selective in a way that does not pass the features and characteristics of the inlet pipe of the pressure loss and separation efficiency can have a significant impact on. Using Wind separator for selection of waste in the waste prior research on the aerodynamic properties are essential. For plastic cases, it is reasonable to take the drag coefficient between 0.8 and 1.0, and for cans, compression depending on whether the cans, the drag coefficient is in the range from 0.2 to 0.7. The separation efficiency of waste as change suction speed was the highest efficiency when the suction speed was 25~26 m/s. Shape of the inlet, depending on how the transfer pipe of the duct pressure loss occurs because the inlet velocity changes through the appropriate design standards to allow for continued research is needed.

• Applied Chemistry for Engineering
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• v.20 no.3
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• pp.266-272
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• 2009

Physical and chemical properties of waste LCD glass were investigated to test the feasibility of feed materials for the production of foamed glass. For this study, chemical analysis, thermal analysis, rheological consideration with the viscosity change under high temperature and thermal expansion coefficient were carried out and the trial production of foamed glass as; in spherical and block type also attempted. All results showed waste LCD glass would be a good feed material for the production of foamed glass and foaming technology of LCD glass would be an effective recycling alternative.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.192-199
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• 2010

This research produced internal model tester ($2.0m{\times}2.0m{\times}1.0m$) to evaluate the field application of Paju Unjeong District water recycling system for small streams eco-friendly river bed disparity method for the first time in Korea and conducted comparative analysis of the Paju Unjeong District water recycling system field test results and infiltration rate result of internal tests by each rainfall intensity following surface material. Infiltration rate result of internal tests concrete pavement by rainfall intensity following surface material, asphalt pavement, bentonite mate, stabilized soil construction and mixed soil construction manifested low infiltration rate. On the contrary, compaction soil, grassland and water permeable packaging materials resulted in significant amount of infiltration rate. As for the field permeability test results, they were manifested similar tendency as indoor permeability test results and they satisfied the standard for standard of water permeability of domestic disparity facility (less than $1.0{\times}10-7cm$/sec). As compaction rate increased, unconfined compression strength increased as well while coefficient of water permeability decreased.

• Resources Recycling
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• v.24 no.6
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• pp.54-60
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• 2015

The objective of this study is to develop a belt-type dryer with a capacity of 1 ton/day, thereby improving drying efficiency by more than 70% and reducing the size of dryers by more than 50%, and thus making dryers smaller and lighter to reduce the installation and operation costs by more than 20%. We identified structural improvements by analyzing existing dryers employing indirect heating and verified the superior drying performance of the proposed method through some basic experiments. Furthermore, we verified the improvements in the heat transfer and drying characteristics as we conducted the experiments at reduced pressure.

• Journal of Korea Water Resources Association
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• v.38 no.4 s.153
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• pp.293-300
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• 2005

This study analyzes hydrometeorologic changes after a dam construction, and develops a model related to estimating the geographical boundary hour far hydrometeorologic changes could happen due to a dam construction. The model is applied to several dams, namely Seomjin Dam, Soyang Dam, Andong Dam, and Chungju Dam. Throughout estimating the correlation between albedo and recycling coefficients, the result confirms that the land use changes by dam construction are the critical factor on the recycling of the water in the air. It is also shown that the geographical boundary is highly related to the surface area of a dam. Finally, this model is expected to be applied to estimate its boundary of hydrometeorologic changes by a new dam construction.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.158-165
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• 2014

The enormous quantity of 'Bayer-Process by-products' (BP by-products) discharged by industries producing alumina from bauxite represents an environmental and economical problem. As it is mainly composed of $Fe_2O_3$, $Al_2O_3$, $SiO_2$, CaO and $Na_2O$, it is thought that using BP by-products as a construction material is an effective way to consume such a large quantity of alkaline waste. In this study, This study evaluates the effect of alkali-activated binder based on recycling BP by-products on soil improvement through the evaluation of slope stability and seepage flow numerical analysis. The results of analysis of ground slope safety at dry season and wet season meet standard (Ministry of Land, Infrastructure and Transport, 2006) Especially, when wet season, the ground used soil improving material meet standard, while the ground used soil-nailing method doesn't. Also, permeability coefficient of improved soil is smaller than that of natural soil and saturation depth of reinforced ground surface with improve soil is lower than that of natural soil.

• Resources Recycling
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• v.20 no.1
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• pp.37-45
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• 2011

This study was conducted to recycle flotation tailings as non-sintered construction materials considering the economic and eco-friendly treatments. The particle size distribution( median $220\;{\mu}m$) of flotation tailings from Soon-shin mine was confirmed to be larger than that(median $140\;{\mu}m$) of tailings from Sam-kwang mine. Thus we investigated the properties of non-sintered eco-brick producted with the tailings from Sam-kwang mine and non-sintered water permeable block producted with the tailings from Soon-shin mine. Compressive strength of non-sintered water permeable block which was made with less than 25 wt% of tailings from Soon-shin mine was met with products class(over 14.70 MPa) of water permeable concrete(EL 245) from KEITL. Meanwhile, the coefficient of its permeability wasn't met with the products class( over $1.0{\times}10^{-2}\;cm/sec$). The properties of non-sintered eco-brick with less than 40 wt% of tailings from Sam-kwang mine were satisfied with third class in sintered clay brick products standard(KS L 4201). The non-sintered eco-brick as a result of leaching test on heavy metals by KSLT was verified to be environmentally stabile.

• Journal of the Korea Organic Resources Recycling Association
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• v.21 no.3
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• pp.99-107
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• 2013

In this study, field scale test was conducted to estimate the TMDL coefficients (runoff and leachate:(${\beta}4$)(${\beta}5$)(${\beta}8$)) for the livestock resources applying to agricultural crop land as fertilizer, and the results were obtained as follows. Each waste reduction coefficient(${\beta}4$) was shown to be in the range of 0.94~0.75 for public waste treatment plants and 0.99~0.83 for private waste treatment in the analysis of BOD, COD, SS, T-N, T-P, TOC. Thus private plants showed higher rate. Waste treatment discharge into the land coefficient (${\beta}5$) was also shown to be in the range of 0.4.~0.24 for public plants and 0.75~0.16 for private plants, so it is much lower than other coefficients. However SS and T-P were shown to be much higher for land discharge in private plants than in public plants. Treatment coefficient in the public plants (${\beta}8$) appeared to be average 0.75 for T-P but over 90% treatment efficiency and also large deviation were observed due to 0.2 of some other treatment plants.

• Resources Recycling
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• v.25 no.6
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• pp.50-57
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• 2016

This work was examined the extraction and stripping behavior of rare earths (La, Ce, Pr, Nd, Sm) from the hydrochloric acid solution by Cyanex 572 and compared to the results that of PC88A. Experimental parameters such as equilibrium pH, extractant & strip reagent concentration were observed and extraction percentage, distribution coefficient, stripping percentage and the separation factor of the adjacent element were analyzed. The $pH_{50}$ values was more higher using Cyanex 572 than that of PC88A. As the increase of the extractant concentration, the distribution coefficient of rare earth elements was increased. Stripping percentage of rare earth elementss from the Cyanex 572 was 85% to 95% and PC88A showed 80% to 87%. Separation factor of Ce/La, Ce/Pr, Pr/Nd, Nd/Sm was enhanced about 1.0-5.0 using Cyanex 572 as an extractant in mixture solution.