• Textile Coloration and Finishing
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• v.30 no.4
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• pp.245-255
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• 2018

In this study, cotton fabrics were coated with $TiO_2$ nanoparticles using 3-mercaptopropyltrimethoxysilane(3-MPTMS), which is highly reactive to cotton fabrics, as a medium, and the characteristics, antimicrobial properties, and photodegradation properties of the fibers were measured. The manufacturing process is as follows. (1) 3-MPTMS was added to isopropanol, and $TiO_2$ colloid was added to the mixture to prepare a solution. (2) Cellulose fibers were immersed in the prepared $3-MPTMS/TiO_2$ solution, stirred for 90 minutes at $45^{\circ}C$ in a constant temperature water bath, and dried thereafter. In order to identify the morphology of the cellulose fibers coated with $TiO_2$ nanoparticles, the surface was observed with a scanning electron microscope(SEM), and SEM-EDS was measured to identify the adhesion of $TiO_2$ nanoparticles. The SEM images showed $TiO_2$ nanoparticle and 3-MPTMS coated layers on the fibers and it was identified that $TiO_2$ nanoparticles were attached to the cellulose fibers. The antimicrobial activity of $3-MPTMS/TiO_2$-treated cotton fabrics was measured using a bacterial reduction method. $3-MPTMS/TiO_2$ cellulose fibers which was irradiated by ultra violet light, showed antimicrobial activity against Escherichia coli(ATCC 43895) and Staphylococcus aureus(ATCCBAA-1707) unlike unirradiated fibers. The cellulose fibers were stained with methylene blue and the photodegradation performance of the stained fabrics was analyzed. The stained fabrics showed high degradation performance with photolytic reactions of $TiO_2$ nanoparticles.

• Textile Coloration and Finishing
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• v.30 no.4
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• pp.294-303
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• 2018

In this study, eco-friendly natural dyeing for pig leather was explored by using onion skin which is food waste. Sodium caseinate was used as a pre-treatment agent to improve dyeability of pig leather and its effect on dye uptake was investigated according to treatment concentration. Dye uptake of the pre-treated pig leather was increased by about two times compared to untreated one at 0.2% pre-treatment concentration. Onion skin colorant imparted YR color on pig leather. After mordanting, the color of pretreated/dyed pig leather was varied from brick-red to khaki shades. However, mordanting did not improved dye uptake of the pre-treated/dyed pig leather significantly. The color-fastnesses of un-mordanted samples to light, dry cleaning, rubbing were grades 3-4, 5, and 4, respectively, which is good enough to meet all Korean Standard for Fastness of leather products. After mordanting, the light fastness of pig leather was improved to 4, 4-5 grade. The efficacy of sodium caseinate as a pre-treatment agent for pig leather was verified by improved dye uptake and good colorfastness. And, the natural dyeing of pig leather using food waste would be a significant sustainable way in terms of eco-friendliness and reuse of biomass to reduce environmental pollution.

• Membrane and Water Treatment
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• v.10 no.4
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• pp.287-298
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• 2019

Lotus leaf has a special dual micro and nano surface structure which gives its highly hydrophobic surface characteristics and so-called self cleaning effect. In order to endow PVDF hollow fiber membrane with this special structure and improve the hydrophobicity of membrane surface, PVDF hollow fiber composite membranes was obtained through the immersion coating of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) dilute solution on the outside surface of PVDF support membrane. The prepared PVDF composite membranes were used in the vacuum membrane distillation (VMD) for the desalination. The effects of PVDF-HFP dilute solution concentration in the dope solution and coating time on VMD separation performance was studied. Membranes were characterized by SEM, WCA measurement, porosity, and liquid entry pressure of water. VMD test was carried out using $35g{\cdot}L^{-1}$ NaCl aqueous solution as the feed solution at feed temperature of $30^{\circ}C$ and the permeate pressure of 31.3 kPa. The vapour flux reached a maximum when PVDF-HFP concentration in the dilute solution was 5 wt% and the coating time was kept in the range of 10-60 s. This was attributed to the well configuration of micro-nano rods which was similar with the dual micro-nano structure on the lotus leaf. Compared with the original PVDF membrane, the salt rejection can be well maintained which was greater than 99.99 % meanwhile permeation water conductivity was kept at a low value of $7-9{\mu}S{\cdot}cm^{-1}$ during the continuous testing for 360 h.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.57-65
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• 2019

In this study, the quality characteristics of the mother material of panel were evaluated for the production of moss panel using alumina cement and biological characteristics and environmental impact characteristics of moss panel were evaluated. The ratio of W/B 10%, Vs/Vm 20% and foaming agent 0.5% were selected as the basic mixing ratio for the mother panel of moss panel through pretest and SAP was added to improve the moisture content of panel. The optimal mixing ratio of SAP was considered to be less than 0.5% considering the quality characteristics. Also, through the use of alumina cement, the pH of the panel could be lowered to 10~11. The panel was able to improve the surface roughness through the foaming agent, and it was confirmed that the SAP had an effect of improving the moisture content of the panel. For the environmental impact characteristics of the moss panel, the moss panel evaluated the carbon dioxide reduction performance and the fine dust cleaning performance.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.45-50
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• 2021

As the difficulty of flip chip products increases, there is a growing interest in the material of flux, which is safe from the solder wetting and reliability. In the case of no clean flux, there is merit in terms of process efficiency because there is no cleaning process. But Cu migration and delamination can be occurred if the residue remains after the reflow process. In this study, major element materials, solvent and activator, are changed and confirmed effect of non-wet and reliability in the package environment. Stability of materials were secured through storage stability evaluation, and we found out non-wet zero materials through the application of two types of solvent and activator with different boiling point and the increase of activator content. After reliability test, no delamination was found in the plane analysis, which secured the final composition of low residue flux.

• Journal of Korea Foundry Society
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• v.41 no.4
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• pp.342-348
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• 2021

Almost all ferrous foundries use press scrap as the main charge material. In this study, we tried to reduce the melting energy by optimizing the shape and size of press scrap. The experiment was conducted using 3t/h medium frequency induction melting furnaces at two foundries. In the case of the improved condition, customized press scrap was used for initial charging, and small press scrap was used for additional charging. The energy reduction effect of the improved condition was enhanced by reinforcing the cleaning process of the return scrap surface. The reduction ratios of the melting energy basic unit by the improved condition at the two foundries were almost the same (23.3 and 23.9%). The improved condition was very effective in both foundries with different basic unit levels. The reasons for energy reduction and the economic effects of the improved condition were described.

• Journal of Convergence for Information Technology
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• v.12 no.5
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• pp.298-304
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• 2022

In this study, it is intended to provide basic research data on hair loss and problematic scalp that is expanding to lower age groups and women. When using Company B's hair ampoule containing L-Menthol, Salicylic acid, and Dexpanthenol daily for women in their 20s with problematic scalp, the effect on the scalp and hair after 4 weeks was investigated. As a result of this study, when using Company B's ampoule containing L-Menthol, Salicylic acid, and Dexpanthenol, the subjects showed improvement effects such as relieving inflammation, reducing scalp fever and erythema, reducing itching and hair loss, and increasing hair thickness. In addition, it was confirmed that the scalp self-diagnosis of the subjects showed improvement effects on scalp satisfaction, scalp vitality and elasticity, heat generation, scalp pulling after cleaning, and itching. Through these research results, it is believed that products containing L-Menthol, Salicylic acid, and Dexpanthenol will help improve problematic scalp and hair.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_2
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• pp.561-570
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• 2023

This study was to evaluate the effect of different rinsing times and methods on the accuracy of temporary prostheses fabricated by 3D printing method. Sixty temporary prostheses were fabricated with LCD types of 3D printer(Halot-Sky, Creality, Shenzhen, China) and divided into six groups (n = 10) based on rinsing times and methods. All specimens were rinsed with 99% isopropanol alcohol for 5 and 10 min using three methods-hand washed, ultrasonic cleaning, and automated washing. All specimens were polymerized for 3 minutes under the same conditions. The marginal and internal gaps of specimens were examined using a replica technique. The light-body silicone thickness was measured at 6 reference points(Absolute marginal discrepancy, Marginal, Chamfer, Axial, Angle, and Occlusal gap). All measurements were performed by a stereomicroscope. Reference point images were taken at 100× magnification and then measured using an image analysis program. Statistical analysis was performed using Two-way ANOVA, One-way ANOVA, and the Kruskal-Wallis test (p = .05). The marginal and internal gaps were statistically different according to the rinsing methods and rinsing times(p < .001). In the rinsing time, the temporary prosthesis rinsed for 5 minutes group showed higher accuracy than 10 minutes group. In the rinsing method, the hand washing group showed higher accuracy than the automated washing group.

• Restorative Dentistry and Endodontics
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• v.46 no.3
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• pp.33.1-33.12
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• 2021

Objectives: This study aimed to investigate the efficacy of ionic and non-ionic-based contrast media (in vitro study) and the combinatorial effect of chitosan-based endo-radiopaque solution (CERS) (in vivo study) for visualization of the root canal anatomy. Materials and Methods: In vitro study (120 teeth): The root canal of maxillary premolars and molars (in vitro group 1 and 2 respectively, n = 60 each) were analyzed using 4 different contrast media (subgroups: Omnipaque 350, Iopamidol, Xenetix 350, and Urografin 76; n = 15 each) in combination with 5.25% sodium hypochlorite (NaOCl). Based on the results of the in vitro study, in vivo study (80 teeth) was done to compare Xenetix 350 + 5.25% NaOCl with CERS (in vivo group 1 and 2 respectively, n = 40 each) on maxillary and mandibular premolars and molars. Two endodontists used radiovisiography to assess the depth of ingress and identify the aberrant root anatomy after access cavity preparation, and after initial cleaning and shaping of canals. Kruskal-Wallis test was used for in vitro comparison (p < 0.05), and Wilcoxon signed-rank test and Mann-Whitney U test for in vivo analysis (p < 0.01). Results: In vitro study, Xenetix 350 + 5.25% NaOCl facilitated a significant higher visualization (p < 0.05). For in vivo study, CERS had a statistically significant depth of ingress (p < 0.01), and was efficient in identifying the aberrant root canal anatomy of premolars and molars. Conclusions: CERS facilitates better visualization of the root canal anatomy of human premolars and molars.

• Journal of People, Plants, and Environment
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• v.22 no.1
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• pp.65-73
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• 2019

The purpose of the study was to examine the effects of the Horticulture Job Skill course based on the employment practice model on personal performance indicator of vocational rehabilitation for university students with disabilities. In the first step of this study, an employment practice model was developed by a focus group composed of six specialists from the industry and academia. The second step consisted of selecting the items of personal performance indicator related to horticulture vocational rehabilitation among all items of vocational rehabilitation. The third step was selecting students to participate in the study. The next step was coming up with a pilot instructional design based on the employment practice model. The final step was examining the effects of pilot course (horticulture job skill) based on the employment practice model on personal performance indicator of vocational rehabilitation for university students with disabilities. As a result, there were significant improvements after treatment in the experimental group with indicator 1 (managing) from 1.8±0.155 to 4.2±0.267, indicator 2 (planting) from 1.5±0.114 to 4.45±0.153, indicator 3 (using tool) from 3.2±0.186 to 4.6±0.112, indicator 4 (packing) from 2.05±0.153 to 4.45±0.114, indicator 5 (decorating) from 2.65±0.150 to 5.5±0.114, indicator 6 (cleaning) from 2.85±0.131 to 4.45±0.114, indicator 7 (observing) from 2.4±0.112 to 4.45±0.112, and indicator 8 (laboring) from 2.35±0.109 to 4.1±0.180. However, the control group did not show any significant improvement after 15 weeks of the program. This study determined that the Horticulture Job Skill course based on the employment practice model has an effect on improving the individual performance of vocational rehabilitation for university students with disabilities. Finally, horticulture education-based on the employment practice model will contribute to vocational rehabilitation for university student with disabilities.