• Composites Research
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• v.22 no.2
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• pp.1-6
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• 2009

The mechanical characteristics of gamma-ray irradiated UHMWPE specimens were investigated under various heat treatment conditions. The heat treatment was performed in the range of annealing and remelting temperatures. The annealing treatment below the temperature of $130^{\circ}C$ hardly induced changes in the tensile strength, the strain at the failure and the hardness. However the remelting treatment above $140^{\circ}C$ deteriorated those mechanical properties. It was shown in an FTIR analysis that the annealing treatment caused some oxidation of free radicals created by the pretreatment of the irradiation. These quantitative data represented by the behavior of mechanical properties might be used as basic informations for the design and analysis of various artificial joints.

• Journal of the Institute of Convergence Signal Processing
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• v.2 no.4
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• pp.77-84
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• 2001

Since Hopfield introduced the neural network for liner programming problems many papers have been published about it and some of them are about nonlinear programming problems Therefore nonlinear, cost function problem has been solved however nonlinear constraints problem has not been solved In this paper I have proposed the general nonlinear programming neural networks which minimize cost function with nonlinear constraints.

• The korean journal of orthodontics
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• v.31 no.1 s.84
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• pp.137-147
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• 2001

Acidic primer is the bonding agent which combines the conditioning and priming agent into the single solution and was originally developed for the dentin bonding system. It is less harmful to the tooth structure and more convenient to manipulate than the traditional etching procedure. The Purpose of this study is to evaluate the shear bond strength of various bonding materials when the enamel is treated with acidic primer for the bracket bonding procedure. Fifty recently extracted human premolars were randomly separated into five groups -Group I using Clearfil Liner Bond 2 adhesive system to the enamel treated with acidic primer, Group II using Transbond XT adhesive system to the enamel treated with acidic primer, Group III using panavia 21 adhesive system to the enamel treated with acidic primer, Group IV using Fuji-Ortho LC adhesive system to the enamel treated with acidic primer, Group V using Transbond XT adhesive system to the enamel treated with 37$\%$ phosphoric acid. The shear bond strength was measured with Instron universal testing machine after storing in $37^{\circ}C$ water bath for 48 hours. After debonding, the teeth and brackets were examined under scanning electron microscope (SEM) and assessed with the adhesive remnant index (ARI). The results were as follows : 1. There were no significant differences in shear bond strength between group III ($8.69{\pm}2.72MPa$), group IV (9.7 ± 3.16 MPa), and group V ($10.48{\pm}2.60MPa$) (p>0.05). 2. The shear bond strength of group III and group IV was significantly higher than that of group I ($1.09{\pm}0.53MPa$), and Group II ($2.70{\pm}1.46MPa$) (p<0.05). 3. The ARI of group IV ($2.1{\pm}1.1$) and group V ($2.9{\pm}0.3$) was significantly higher than that of group I ($0.2{\pm}0.4$), group II ($0.3{\pm}0.9$) and group III ($0.2{\pm}0.4$) (p<0.05). 4. There were no significant difference between the ARI of group IV and group V (p>0.05). This result suggests that the combination of acidic primer and some bonding adhesive can provide sufficient shear bond strength for clinical orthodontics.

• The Journal of Korean Academy of Prosthodontics
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• v.36 no.1
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• pp.50-63
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• 1998

This study investigated the effects of resin surface primers for rebase resins on the surface texture of denture base resins by the use of scanning electron microscopy. This study also evaluated the bond strength of rebase resins to denture base resin. The denture base resin in this study was Vertex RS (Dentimex Co., Ltd., Holland). The rebase resins used were Tokuso Rebase (Tokuyama Co., Ltd., Japan), Metabase (Sun Medical Co., Ltd., Japan), New True Liner(Harry J, Bosworth Co., Ill.), and Reverse (Nissin Co., Ltd., Japan). The test samples were divided into four parts: Group 1 : Treated with primer with brush. Group 2 : Immersed in the primer for 5 seconds. Group 3 : Immersed in the primer for 10 seconds. Group 4 : Immersed in the primer for 30 seconds. Control group : not treated with primer The results were as follows; 1. The bond strength of rebase resins to denture base resin is increased by application of primers. 2. Regardless of the rebase resin type, there was no significant difference among the bond strength in groups G1, G2, G3, G4. There was a significant difference with the control. (P<0.05) 3. Regardless of each group, the bond strength according to the rebase resin type was decreased in the following order: Tokuso Rebase, New Tru Liner, Reverse and then Metabase. 4. Under the scanning electron microscope, brush application produced a softening of the denture base surface. After immersion, all primers produced a spongelike structure on the denture base resin surface. The results of this study suggest that primers produce a significant effect by means of brush application, therefore it is recommended as the most convenient and logical procedure for application of the primers.

• Korean Journal of Food Science and Technology
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• v.38 no.6
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• pp.762-766
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• 2006

To improve water resistance of paperboard used to manufacture the corrugated boxes, effect of surface coating of the liner- board with Na-alginate was investigated by determining the optimum processing conditions such as a optimum alginate concentration for surface coating, plasticizer content, concentration of divalent cations their immersion times, For the surface coating of the liner-board, 2.5% Na-alginate solution was found to be the optimum concentration, and the concentration of glycerol used as plasticizer was effective when 35% alginate concentration was use was Used Immersion of the alginate coated paperboard for 3 min in a $CaCl_2$ solution improved the water resistance properties. As a divalent cation for the insolubilization of the alginate films, $Cu^{2+}$ was found to be as effective as $Ca^{2+}$. Among the platicizers tested, sorbitol was the most effective in reducing water vapor permeability and water solubility of alginate coated paperboard.

• Journal of the Korean Geosynthetics Society
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• v.2 no.3
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• pp.11-18
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• 2003

The one of the most important concerns in the design of the final cover system is to restrict percolation of water into the waste body. To minimize entering the water, the final cover system has the barrier layer that consists of a single compacted clay liner(CCL) or a composite liner with high density polyethylene(HDPE) overlying CCL. The HDPE as well as CCL can be damaged by landfill settlements. Therefore, this study was conducted to assess the effects of HDPE induced by settlements in the final cover system after closure. The results of the three test that is field test, lysimeter test in laboratory, and prediction of settlement represent that the HDPE in the final cover system is not pretty much affected by settlements and stable on settlements.

• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.227-241
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• 1996

The effect of collagen dissolution in acid conditioned dentin was morphologically examined by both scanning and transmission electron microscopy. 18 freshly extracted human molars and dentin bonding systems of All Bond 2, Scotchbond Multipurpose, Superbond D-Liner were used in this study. For SEM preparation, each 3 of ~ exposed dentin surfaces were acid conditioned by using various acids within the above three bonding systems respectively. After acid conditioning of the other 3 exposed dentin surfaces as above, they were treated with 1.7% NaOCl for 2 minutes. The remaining 3 dentin surfaces were acid conditioned and treated with 3.3 % NaOCl for 2 minutes. All of the specimens were then fixed in 4 % glutaraldehyde for 12 h at $4^{\circ}C$ and dehydrated in ethanols grades from 50 % to 100 %, then surface changes of the specimens were observed by using SEM. For TEM preparation, exposed dentin surfaces were acid conditioned with the same acid as SEM specimens and treated with 1.7%, 3.3 % NaOCl respectively, then applied with corresponding bonding agents. After the procedures were finished, composite resin were applied on the dentin surfaces and light cured. Small, rectangular sticks with end dimensions of approximately 1 by 1 mm were sectioned and further sample preparative techniques for transmission electron microscopy were performed in accordance with the procedures used for ultrastructural TEM observations of calcified tissues. The results were as follows : 1. In the 1.7 % NaOCl retreated specimens after acid conditioning, the porous dentin surface of intertubular dentin and wide opening of dentinal tubules were appeared. And there were fine irregularities on the intertubular dentin, indicating a clear difference as compared with the acid conditioned specimens. 2. In the 3.3% NaOCl retreated specimens after acid conditioning, the intertubular dentin was further eroded causing a more porous and wider opening of dentinal tubules. Moreover, sharp irregularities on the intertubular dentin were more evident than those of acid conditioned and 1.7% NaOCl retreated specimens. 3. In all of the acid conditioned specimens, the resin-dentin hybrid layer of approximately 3.5mm thickness was formed and the collapsed collagen layer was observed on the uppermost part of hybrid layer in the specimens applied with All Bond 2. The collgen fibrils of intertubular dentin in specimens applied with Scotchbond Multipurpose were running perpendicular to the interface, and electron dense black layer demarcated from the deep unaltered dentin was more evident in the specimen applied with Superbond D-Liner than any other specimens. 4. In the 1.7 % NaOCl retreated specimens after acid conditioning, the resin-dentin hybrid layer of approximately 2.5-3.0mm thickness was formed and the collapsed collagen layer and longitudinally running collagen fibrils as shown in the acid conditioned specimens were observed in the specimens applied with All Bond 2 and Superbond D-Liner. 5. In all of the 3.3% NaOCl retreated specimens after acid conditioning, the evidence of resin-dentin hybrid layer was not identified ; nevertheless, the longitudinally running collagen fibrils remained slightly in the specimens applied with All Bond 2.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.856-868
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• 1995

The effect of collagen dissolution in acid conditioned dentin layer on resin - dentin adhesion was investigated. 160 freshly extracted human molars were divided into 4 groups randomly and dentin surfaces were exposed. 40 exposed dentin surfaces were not acid conditioned and each 10 of them were applied with bonding agents within dentin bonding systems of All Bond 2, Scotchbond Multipurpose, Clearfil Photobond and Superbond D - Liner respectively. Each 10 of another 40 exposed dentin surfaces were acid conditioned by the acid within the above four bonding systems respectively and applied with corresponding bonding systems. After acid conditioning of the other 40 exposed dentin surfaces as above, they were treated with 5% NaOCl for 2 minutes, and each 10 of them were applied with the above four dentin bonding systems respectively. The remaining 40 dentin surfaces were acid conditioned and treated with 10% NaOCl for 2 minutes, and each 10 of them were applied with corresponding bonding agents as the above. After the procedures were finished, composite resin (Z -100, 3M Dent. Prod., USA) were applied on the dentin surfaces and light cured. Shear bond strength values were measured. Surface changes of fractured dentin specimens were observed using SEM (Hitachi S-2350, Japan). The following results were obtained. 1. In all of dentin bonding systems, shear bond strengths of non - conditioned specimens were significantly lower than those of acid conditioned specimens (P<0.05). 2. A statistically significant difference of bond strengths did not exist between acid conditioned specimens and 5% NaGCI retreated specimens applied with All Bond 2, Scotchbond Multipurpose and Clearfil Photobond (P>0.05). However, strength values of 5% NaOCl retreated specimens applied with Superbond D - Liner were lower than those of acid conditioned specimens (P<0.05). 3. In all the applied dentin bonding systems except Clearfil Photobond, bond strengths of 10% NaOCl retreated specimens were lower than those of acid conditioned and 5% NaOCl retreated specimens (P<0.05). 4. The resin - dentin hybrid layer of 4 - $5{\mu}m$ thickness was formed in the acid conditioned specimens applied with All Bond 2, Scotchbond Multipurpose and Superbond D-Liner. 5. The resin - dentin hybrid layer of 3 - $4{\mu}m$ thickness was still formed in the 5% NaOCl retreated specimens applied with All Bond 2 and Scotchbond Multipurpose. In addition, this layer was not completely removed after the retreatment with 10% NaOCl. Above results indicate that the dissolution of collagen in acid conditioned dentin layer by NaOCl solution can not be achieved completely and the collagens contribute to the resin - dentin adhesion considerably.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.66-73
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• 2019

Approximately 80% of the mines are vacated or abandoned mines and are mostly left without suitable environmental treatment facilities. In the area around the abandoned mine site, problems such as drainage of acidic city drainage and leakage of leachate occur, and ground subsidence caused by this can cause a safety accident due to sink hole occurrence. In this study, flow, compressive strength, water uptake, pore and hydration characteristics were investigated to investigate the basic properties of liner and cover material based on the replacement ratio of nano silica and silica fume in the existing blast - furnace slag fine powder. As a result, as the substitution ratio of nano silica and silica fume increased, the flow and compressive strength of nano silica specimens increased and the absorption rate decreased. In the case of pore characteristics, the amount of pores decreased as the substitution ratio of nano silica and silica fume increased. Especially, the capillary porosity of 10-1,000 nm diameter decreased. Ray diffraction analysis and SEM measurement showed that the peak positions of the hydration products were almost the same when compared with the 5% alternative test samples of Plain and silica fume.

• Journal of the Korean Society of Safety
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• v.6 no.2
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• pp.21-30
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• 1991

In this paper, we study effect of waveness at the optical surface roughness measurement. In generally, waveness components cause errors in calculation of the roughness value of metal surface. We study about surface roughness signals In the frequency domain for separate two signal component of real roughness and waveness by digital signal processing methods. Thereafter, determine low and high Component of frequency spectrum. By this separating frequency value we design liner low and high pass filter which cutoff frequency is 1 Hz. After this process, converted each filtered spectrum by inverse discrete fourier transformation to time domain waveness and real roughness signals We calculate surface roughness value from filtered roughness signals. For evaluate this method, we use five specimens roughness signal which obtained from optical surface roughness measuring system in 3mm/s moving speed with 0.1 mm laser beam spot size As a result, we obtain more linerized roughness value than that of unfiltered roughness signals.