• Journal of Sericultural and Entomological Science
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• v.36 no.1
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• pp.58-61
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• 1994

This study was carried out to investigate the physical characteristics of stocking knitted with silk/nylon(S/N) compound yarn. In SEM observation, it was found that most part of S/N stocking was well interlaced between silk and nylon yarn. There was no difference between S/N stocking and nylon stocking in shrinkage at warm water and compressive resilience. The suction height and absorbability of S/N stocking was 4~8 times and 3 times higher than that of nylon stocking, respectively. According to the wearing test survey, most of wearers answered that the warmth, the hand and the feeling cool of S/N stocking were better than those of nylon stocking but reversed in elasticity, and they gave sprit opinion on durability responding good impression in total feeling of S/N stocking.

• Macromolecular Research
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• v.17 no.6
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• pp.378-387
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• 2009

This research compared three methods for producing and processing nanocomposite polypropylene filament yarns with permanent antimicrobial efficiency. The three methods used to mix antimicrobial agents based on silver nano particles with PP were as follows: 1) mixing of PP powder and inorganic nanocomposite filler with the appropriate concentration using a twin-screw extruder and preparing granules, 2) method 1 with a singlerather than twin-screw extruder, and 3) producing the masterbatch by a twin-screw extruder and blending it with PP in the melt spinning process. All pure polypropylene samples and other combined samples had an acceptable spinnability at the spinning temperature of $240^{\circ}C$ and take-up speed of 2,000 m/min. After producing as-spun filament yarns by a pilot plant, melt spinning machine, the samples were drawn, textured and finally weft knitted. The physical and structural properties (e.g., linear density, tenacity, breaking elongation, initial modulus, rupture work, shrinkage and crystallinity) of the as-spun and drawn yarns with constant and variable draw ratios (the variable draw ratio was used to gain a constant breaking elongation of 50%) were investigated and compared, while DSC, SEM and FTIR techniques were used to characterize the samples. Finally, the antibacterial efficiency of the knitted samples was evaluated. The experimental results revealed that the crystallinity reduction of the as-spun yarn obtained from method 1 (5%) was more than that of method 2 (3%), while the crystallinity of the modified as-spun yarns obtained with method 3 remained unchanged compared to pure yarn. However, the drawing procedure compensated for this difference. By applying methods 2 and 3, the drawing generally improved the tenacity and modulus of the modified fibers, whereas method 1 degraded the constant draw ratio. Although the biostatic efficiency of the nanocomposite yarns was excellent with all three methods, the modified fabrics obtained from methods 1 and 2 showed a higher bioactivity.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.885-892
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• 2005

Recently, the damaged concrete structures are often strengthened or repaired using the polymer concrete or the polymer cement mortar. In the repaired concrete structures at early ages, internal stresses could be developed due to the differential drying shrinkage of the repair material. Due to the difference of the thermal coefficients of the repair material and existing concrete, additional stresses also could be developed as the structures are subjected to the ambient temperature changes. Theses environmentally-induced stresses can sometimes be large enough to cause damage to the structures, such as debonding of the interface between the two materials. In this study, a rational procedure was developed where anchors can be designed and installed to prevent damages in such structures by thermally-induced stresses. Finally, through the experimental study and numerical study, the effects of the repair method using anchors with debonding was investigated and discussed the results.

• Journal of Ginseng Research
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• v.19 no.1
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• pp.62-72
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• 1995

During the controlled atmosphere storage (CA), fresh ginseng showed good appearance in quality, and other deterioration of freshness was not observed until 12 weeks. On the other hand, MA storage had kept freshness only in treatment of 1 until 8 weeks. There was no significant difference between treated and non-treated sample with preservatives, and not treated sample was not infected with various different fungi. Moisture contents and hardness of ginseng in all treatments were not changed much until 12 weeks, and surface shrinkage did not occur either. But shear stress increased somewhat in all treatments after 12 weeks. The granule of microstructure in tissue diminished slightly. The apparent Quality of red ginseng was good until 4 weeks of treatment. But as time passed, white skin and wrinkled skin were generated and darkened in its color. B-1 in CA and E-1 in MA were found to be the most favorable one. The content of crude saponin did not change significantly during storage of CA or MA by preservation conditions and period. Though a small increase in saponin content from 4.92% to 5.43% was recognized in B-1, which was treated with preservative and 6.0% In B-2, control, this could rather explain increment of soluble component by butanol. Thus, there was no change in total contents of ginsenoside pattern and composition of each content. The Rbl content in B-1 and B-2 were 0.98%, and 0.97%, respectively, whereas that of control was 0.96%. E-1 of MA, treated with preservative was 5.32% after 12 weeks, but was 5.73% in control, indicating that ginsenosides pattern was quite similar to that of CA storage.

• Restorative Dentistry and Endodontics
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• v.40 no.1
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• pp.23-29
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• 2015

Objectives: The aim of this study was to evaluate the effect of pre-etching on the bond strength of silorane-based composite specific adhesive system to dentin. Materials and Methods: Thirty human molars were randomly divided into 5 groups according to the different bonding strategies. For teeth restored with silorane-based composite (Filtek Silorane, 3M ESPE), the specific self-etching adhesive system (Adhesive System P90, 3M ESPE) was used with and without pre-etching (Pre-etching/Silorane and Silorane groups). Teeth restored with methacrylate based-composite (Filtek Z250, 3M ESPE) were hybridized with the two-step self-etching system (Clearfil SE Bond, Kuraray), with and without pre-etching (Pre-etching/Methacrylate and Methacrylate groups), or three-step adhesive system (Adper Scotchbond Multi-Purpose, 3M ESPE) (Three-step/Methacrylate group) (n = 6). The restored teeth were sectioned into stick-shaped test specimens ($1.0{\times}1.0mm$), and coupled to a universal test machine (0.5 mm/min) to perform microtensile testing. Results: Pre-etching/Methacrylate group presented the highest bond strength values, with significant difference from Silorane and Three-step/Methacrylate groups (p < 0.05). However, it was not significantly different from Pre-etching/Silorane and Methacrylate groups. Conclusions: Pre-etching increased bond strength of silorane-based composite specific adhesive system to dentin.

• Resources Recycling
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• v.28 no.1
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• pp.32-39
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• 2019

The present study investigated hydration of alkali activated slag incorporating sulfate as a form of anhydrite by employing thermodynamic modeling using the Gibbs free energy minimization approach. Various parameters were evaluated in the thermodynamic calculations, such as presence of sulfide, precipitation/dissolution of AFt/AFm phase, and the effect of oxic condition on the predicted reaction. The calculations suggested no significant difference in the void volume and chemical shrinkage, which might influence the performance of the mixtures, in spite of various changes of the parameters. Although the types of hydration products and their amount varied according to the input conditions, their variations were smaller range than that induced by water-to-binder ratio. Moreover, it did not affect the amount of C-(N-)A-S-H which was the most important hydration product.

• Imaging Science in Dentistry
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• v.52 no.2
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• pp.209-217
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• 2022

Purpose: The aim of this study was, firstly, to determine the concordance of ultrasonographic and histopathological diagnoses in patients in whom apical resection was already indicated. Secondly, this study aimed to determine whether lesions were periapical granulomas or cysts, and to compare them after root canal treatment using ultrasonography and periapical radiographs. Materials and Methods: In the first stage of the study, ultrasonographic and histopathologic diagnoses of 10 lesions were compared. Secondly, the periapical radiographs and ultrasonographic images of 44 lesions were measured. The presence of internal vascularity was determined by ultrasonographic color and power Doppler modes. Follow-up examinations of healing after root canal treatment were performed using ultrasonography and periapical radiographs, and these modalities were compared. Results: In the periapical granuloma and cyst groups, the measurement values decreased for all variables. There was no significant difference in the dimensional changes of lesions between the 2 groups, and ultrasonography and periapical radiographs were compatible. The pre-diagnoses were compared with histopathological diagnoses and were found to be compatible. Conclusion: The ultrasonographic color and power Doppler techniques could be an effective method for diagnosing periapical lesions as cysts or granulomas. After root canal treatment of granulomas and cysts, the dimensional shrinkage and healing patterns appear to be similar. Ultrasonography and periapical radiographs were consistent in terms of dimensional comparisons, and ultrasonography may be an alternative method for follow-up of the healing of periapical lesions.

• Journal of Forest and Environmental Science
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• v.39 no.1
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• pp.55-64
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• 2023

Properties of a lesser-used wood species were investigated to determine its potential for structural utilization. Trees of Delonix regia were felled and sampled at the base, middle and top and then sectioned to inner wood, middle wood, and outer wood for variation across the axial and radial directions. Hence, selected physical and mechanical properties as well as natural durability of D. regia along the radial and axial directions were examined. Obtained data were analyzed using analysis of variance (ANOVA) at α_0.05. There was no significant difference in the Moisture content (MC) of the wood but specific gravity (SG) decreased from base to top ranging from 0.35-0.44. Water absorption, volumetric swelling, and volumetric shrinkage range from 46.18-51.86%, 2.57-4.02%, and 2.26-3.96% respectively along the axial plane. The weight loss for graveyard exposure and accelerated laboratory decay test ranged from 25.14-48.00% and 32.02-44.45% respectively. Modulus of Rupture and Modulus of Elasticity values range from 29.42-72.68 Nmm² and 3,834.54-8,830.37 Nmm² respectively. The SG values has confirmed the species as a medium density wood and values of other properties tested showed that the wood is dimensional stable and moderately resistance to fungi and termite. Hence, it could be used for light construction purposes such as furniture and other interior woodwork.

• Journal of dental hygiene science
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• v.23 no.2
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• pp.123-131
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• 2023

Background: As a restorative material used to treat dental caries, the light-curing type resin is widely used, but it has the disadvantage of polymerization shrinkage. The Bulk-Fill composite resin was developed to solve these shortcomings, but the existing research mainly focused on comparing the physical properties of a composite resin and a Bulk-Fill resin. A study on the light curing time and distance of the Bulk-Fill resin itself tend to be lacking. Methods: This study compares the surface microhardness of specimens prepared by varying the light curing time and distance of smart dentin replacement (SDR) as a flowable Bulk-Fill resin and Tetric N-ceram as a packable Bulk-Fill resin, and confirms the polymerization time and distance that becomes the optimum hardness. To determine the hardness of the specimen, it was measured using the Vickers Hardness Number (Matsuzawa MMT-X, Japan). Results: In SDR, the surface microhardness decreased as the distance increased in all time groups in the change distance from the curing tip. In the change of light curing time with respect to the distance from curing tip, the surface microhardness increased as the time increased. In Tetric N-ceram, the surface microharness showed no significant difference in the change of the distance of curing tip in the group of 20 and 60 second. But in the group of 10 and 40 seconds, decreased as the distance increased. The surface microharness increased as the light curing time increased in all distance groups. Conclusion: When using SDR and Tetric N-ceram in clinical practice, it is considered that as the distance from the polymerization reactor tip increases, a longer light curing time than the polymerization time recommended by the manufacturer is required.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.3
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• pp.335-340
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• 2017

Composite resin becomes an essential material in pediatric dentistry. However, incremental filling of composite resin to minimize the polymerization shrinkage takes time. To reduce the polymerization shrinkage, clinicians and researchers have focused on bulk-filling materials. Bulk-base composite resin is newly introduced as bulk-filling composite resin. The purpose of this study was to evaluate microhardness profile of bulk-base composite resin according to the depth of cure. A high flow bulk-base material and a low flow bulk-base material were used for experimental group, and a conventional composite resin was used for control group. Each group consist of 20 specimens, $3.5{\times}3.5{\times}5.0mm$ mold was used to make specimen. Specimens were sectioned at the 2 mm and the 3 mm depth with milling machine. Microhardness profile was measured at the surface, 2 mm depth, 3 mm depth, and 4 mm depth. Microhardness of control group showed statistically significant difference (p < 0.05) according to the polymerization depth. In contrast, experimental group showed no statistically significant difference, except between 0 mm and 4 mm at HFB, 0 mm and 2 mm, 0 mm and 3 mm at MFB. At the surface and the 2 mm depth, the control group showed higher microhardness than the experimental groups (p < 0.05). However, at the 4 mm depth, the experimental groups showed significantly higher microhardness (p < 0.05). The results from this study, the bulk-base composite resin showed higher microhardness at the 4 mm and lower microhardness at the surface and the 2 mm depth. Therefore, if bulk-base resin overcomes the mechanical weakness, it could be considered using in pediatric dentistry.