• Membrane and Water Treatment
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• v.13 no.2
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• pp.73-83
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• 2022

In the present study, we compared the adsorption capacity of Pb (II) from contaminated water of used cardboard (UC) and a commercial powdered activated carbon (PAC), the latter has been characterized by different techniques, namely X-ray diffraction (XRD), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), wavelength dispersion x-ray fluorescence (WDXRF), infrared spectroscopy (IR) and surface area B.E.T analyzer. The effect of various parameters, such as the pH, the contact time, the amount of adsorbent, and the temperature on the adsorption of Pb (II) on both materials was investigated. The Pb (II) adsorptions are perfectly described by a pseudo-second-order model, while the intraparticle diffusion is a decisive step after the first minutes of contact. The fit to the Langmuir and Redlich-Peterson models seems perfect for these adsorption reactions. (PAC) showed a greater affinity for Pb (II) compared to (UC) and the adsorption of Pb (II) ions is strongly pH-dependent, on the other hand, the increase in temperature doesn't have much influence on the two solids. This study showed that the capacity of (UC) to adsorb Pb (II) from an aqueous solution is greater than two-thirds of that of (PAC).

• The Journal of the Acoustical Society of Korea
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• v.27 no.8
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• pp.395-402
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• 2008

In viol family string instruments vibration of string is transmitted to the front plate through bridge to cause resonance of the instrument body. Therefore, the vibration of string is the source of sound and the properties, the structure, and the boundary conditions of string are expected to have significant effect on the sound. In this study the vibration of strings in cello when one end is fixed and the other end is pressed with finger tip is studied and compared with the case of the fixed-fixed ends. The result of analysis and experiment shows that the vibration of the string that is fixed at one end and pressed with finger tip at the other end is significantly influenced by the contact condition of the string with the finger tip and also quite different from that of the fixed-fixed string, It also suggests that the sound of a cello can be significantly influenced by the contact condition between the string and the finger tip in the fingered string.

• Journal of Korean society of Dental Hygiene
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• v.23 no.6
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• pp.459-466
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• 2023

Objectives: The purpose of this study was to evaluate the physical properties and antibacterial activity of denture base resin with added silver sulfadiazine. Methods: Specimens were made from self-curing denture base resin and silver sulfadiazine as an inorganic antibacterial agent. For physical evaluation of the specimens, surface roughness, surface hardness, and contact angle were measured. Bacterial growth was assessed by optical densityat 600 nm (OD600) and colony forming units (CFU) measurements to confirm antibacterial activity. Results: There was no significant difference in surface roughness, surface hardness, and contact angle in the experimental group containing silver sulfadiazine compared to the control group. In contrast, the experimental group showed a significant decrease in antibacterial activity compared to the control group in terms of OD value. Analysis of CFU confirmed a significant decrease in colonies in the experimental group compared to the control group. Conclusions: Denture base resin containing silver sulfadiazine, an inorganic antibacterial agent, exhibited enhanced antibacterial activity without physical changes. In conclusion, the use of denture base resin containing inorganic antibacterial agents may be expected in the future.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.197-202
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• 2024

In this study, we propose a method to improve the durability of rotorcraft switches. Additionally, the appropriate verification test results are presented. As a result of analyzing the defective switch, it was found that the contact was defective due to long-term use. It was confirmed that stable contact of the terminal is necessary to achieve appropriate performance. We manufactured a switch with one spring and a switch with two springs. As a result of the verification test using this, it was found that the durability of the improved shape was improved by 15 % compared to the existing shape. Those numbers have merit from an operational perspective. This has the effect of reducing the number of replacements per aircraft.

• East Asian Journal of Business Economics (EAJBE)
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• v.12 no.3
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• pp.1-10
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• 2024

Purpose: In the context of fresh food e-commerce, this study investigates the intermediary mechanisms between last-mile logistics service quality (LMLSQ) and customer loyalty. Utilizing the Quality-Value-Loyalty chain as a framework, it focuses on how perceived functional and emotional value mediate this relationship. Research design, data and methodology: Data was gathered through questionnaires from Chinese customers who purchased fresh products from fresh food e-commerce platforms which provide self-delivery services. Partial least squares structural equation modeling (PLS-SEM) was used to examine the proposed hypotheses after confirmatory factor analysis (CFA) revealed the validity and reliability of the data. Results: The findings reveal that condition quality and personnel contact quality positively influence both functional and emotional value, which, in turn, significantly impact customer loyalty. Timeliness quality, however, does not significantly affect functional or emotional value, indicating its limited impact on customer loyalty. Conclusions: The study confirms that improving condition quality and personnel contact quality significantly boosts customer loyalty by enhancing perceived functional and emotional value. The findings highlight the importance for fresh food e-commerce platforms to offer high-quality, reliable, and emotionally satisfying LMLSQ. The results offer practical insights for e-commerce platforms to focus on specific service quality dimensions to foster customer loyalty and contribute to the theoretical understanding of the quality-value-loyalty framework.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1712-1713
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• 2011

Inkjet technology have many merits in plenty of industrial applications. However, deposited droplet has a very critical issue that is coffee ring effect, for the application to an industrial manufacturing process. To remove the coffee ring effect, the effect of thermal treatment conditions on shapes of inkjet printed silver patterns were investigated in various surface condition. The surface changes were characterized by the contact angle measurement. Droplets from a 50 ${\mu}m$ nozzle were printed on the substrate after optimizing the ejection of individual droplets. Ink with a high boiling point of main solvent results in coffee ring effect. This result implies that the dominant factor that determines the shape of droplet is the drying conditions of main solvent of silver nanoparticle colloidal ink. As a results, selecting a proper thermal treatment conditions is very crucial for better shapes of inkjet printed silver nanoparticle colloidal patterns.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2002.09a
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• pp.187-190
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• 2002

Reductive dechlorination of endosulfans was studied with zero valent metals (ZVMs) and bimetals in aqueous batch reactors. The effect of surfactants was evaluated. Endosulfan was successfully dechlorinated with zero valent iron. However, a bimetal, palladium coated iron (Pd/Fe) showed a highly enhanced reactivity for both endosulfan I and II indicating palladium act as a dechlorination catalyst on the iron. The effect of surfactants on degradation with ZVM has been very controvertible. Variable concentration of a nonionic surfactant, Triton X-100 and an anionic surfactant, SDS were added into the reactor with ZVM. The reaction rates of endosulfan were increased with both surfactants. In the case of Triton X-100, the reaction rate was increased with the increasing surfactant concentration up to 400 mg/L. Addition of small amount of surfactant under the CMC, the reaction rate was increased. However, the enhancing effect was diminished when a higher concentration of surfactant (1,000 mg/L) was used. Current study implicate that the surfactant adsorbed on the metal surface might increase the surface concentration of endosulfan resulting in the increased reaction rate. However, partitioning of endosulfan into the micelle formed at the high concentration of surfactant diminish the enhancing effect by reducing the contact chance between target compound and the metal surface.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.4
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• pp.350-355
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• 2000

Powdered activated carbon(PAC) is widely used to control 2-MIB와 geosmin causing earthy-musty odor in water supplies. It was known that chlorine is one of the chemicals often come into contact with activated carbon. But activated carbon react with chlorine and surface oxide accumulate on carbon surface. As result, adsorption capacity of activated carbon is reduced. To investigate the effect of chlorine on the PAC's ability to adsorb 2-MIB and Geosmin, a series of experiments was carried out to show (1) the effect of aqueous chlorine doses on the ability of PAC to adsorb 2-MIB and Geosmin from Lake Heodong water. (2) the effect of delaying the chlorine addition after PAC had been added (to simulate the effect of using an alternative point of chlorine addition). As a result of experiment, as chlorine dose increased correspondingly decreased the capacity of activated carbon to adsorb 2-MIB and geosmin. Even though previously adsorbed 2-MIB and geosmin released, as result of the application of delaying the chlorine adding was more beneficial than simultaneous adding chlorine with PAC.

• Korean Journal of Veterinary Service
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• v.32 no.1
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• pp.87-92
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• 2009

The avoidance of the allergen of the house dust mite is one of the challenges to reduce and treat the symptoms of allergic diseases. Accordingly, various acaricidal agents are being used to kill the mite, but just killing it leaves the remains of it, which still act as the allergen. Therefore expelling the mite is thought as best policy to avoid the mite allergen. For this, some materials have been applied to repellent agents against the mite. Among them, a material with natural origin, known as the phytoncide, is being used for its repellent activity, as well as for its benefits for health. In this experiment, essential oils extracted from Korean white pine (Pinus koreaiensis S. et Z.) and hinoki cypress (Chamaecyparis obtusa), which are widely used as the source of phytoncide products, are studied for demonstration of the repellent effect against the house dust mites, Dermatophagoides farinae and D. pteronyssinus. Direct contact method was used to evaluate the repellent effect (%). And the results suggest the oils have a significant effect enough to be used as a source of repellent agent. For the repellent effect, the most effective concentration was $0.5{\mu}l/cm^2$ at 45 minutes both in the white pine and the hinoki oil.

• Restorative Dentistry and Endodontics
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• v.39 no.4
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• pp.241-252
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• 2014

The goal of endodontic treatment is the prevention and control of pulpal and periradicular infections. Calcium hydroxide ($Ca(OH)_2$) has been widely used in endodontics as an intracanal medicament to eliminate the remaining microorganisms after chemomechanical preparation. The purpose of this article is to review the antimicrobial properties of $Ca(OH)_2$ as an intracanal medicament in root canal treatment. The first part of this review details the characteristics of $Ca(OH)_2$ and summarizes the results of in vitro studies related to its antimicrobial effect. The antimicrobial effect of $Ca(OH)_2$ results from the release of hydroxyl ions when it comes into contact with aqueous fluids. $Ca(OH)_2$ has a wide range of antimicrobial effects against common endodontic pathogens, but is less effective against Enterococcus faecalis and Candida albicans. The addition of vehicles or other agents might contribute to the antimicrobial effect of $Ca(OH)_2$.