• Journal of Korean Ophthalmic Optics Society
• /
• v.14 no.3
• /
• pp.95-102
• /
• 2009

Purpose: The purpose of this study is to investigate antimicrobial activity of ally derivative of garlic against eye diseases, and to get basic data for an application development of the derivative, as a natural preservative, to multi-purpose solution (MPS). Methods: Antimicrobial activity of allyl derivative of garlic, diallyl sulfide (DAS), against Pseudomonas aeruginosa (P. aeruginosa) and Staphyloccus aereus (S. aereus) was determined. After DAS treatment in MPS of no microbial activity, its growth inhibition effect to bacteria was also determined. Results: DAS concentrations of $IC_{50}$ against P. aeruginosa and S. aereus were found when both bacteria were treated with DAS concentration of 0.25% and 0.64%, respectively. At MPS test, a product from Company A did not show any effects against both bacteria, but one from Company B showed antimicrobial activity against both bacteria. Antimicrobial activity test of the product from Company B in MPS did not showed any significant difference on both gram-negative and gram-positive bacteria. For a trial application of antimicrobial activity of DAS as a natural preservative, DAS was added to MPS of Company A which did not show any antimicrobial activity at treated concentration. Addition of DAS into MPS of Company A resulted in antimicrobial activity of DAS, which suggested a possible application of DAS as a germicide for contact lenses. Conclusions: This study showed allyl derivative of garlic has antimicrobial activity against both P. aeruginosa and against S. aereus, but more effects on P. aeruginosa. The result suggests that allyl derivative derived from garlic can be developed to a preservative of MPS as a natural substance.

• Applied Chemistry for Engineering
• /
• v.23 no.6
• /
• pp.521-528
• /
• 2012

In this study, we analyzed the physical properties of an ethylene oxide adducted amphoteric surfactant such as critical micelle concentration, surface tension, interfacial tension, contact angle, viscosity and phase behavior. The dual function characteristics of an amphoteric surfactant were investigated by determining an isoelectric point, which were attained using zeta potential measurements and quartz crystal microbalance (QCM) experiments. The isoelectric points of DE3-OSA82-AO, DE5-OSA82-AO and DE9-OSA82-AO surfactant systems determined by zeta potential measurements were 6.97, 6.93 and 7.10 respectively and they are in good agreement with the isoelectric point values measured by QCM experiments. The frictional property measured using an automated mildness tester showed that the DE-OSA82-AO surfactant could provide a good softening effect at neutral condition.

• Applied Chemistry for Engineering
• /
• v.31 no.2
• /
• pp.230-236
• /
• 2020

In this study, an adhesive tape with water and impact resistance for mobile devices was developed using a UV-curable urethane acrylate based polymer as a substrate. The substrate fabricated by UV-curable materials shows hydrophobicity and poor wettability, which significantly deteriorates the interface-adhesions between the substrate and acrylic adhesive. In order to improve the interface adhesion, 3-glycidoxy-propyl trimethoxysilane (GPTMS), a silane coupling agent having epoxy functional groups, was selected and incorporated into UV-curable urethane acrylate based polymer resins in various contents. The changes of the chemical composition according to the contents of GPTMS was studied with Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) to know the surface bonding properties. Also mechanical properties of the substrate were characterized by tensile strength, gel fraction and water contact angle measurements. The peel strengths at 180° and 90° were measured to compare the adhesion between the substrate and adhesive according to the silane coupling agent contents. The mechanical strength of the urethane acrylate adhesive tape decreased as the silane coupling agent increased, but the adhesion between the substrate and adhesives increased remarkably at an appropriate content of 0.5~1 wt%.

• Journal of Distribution Science
• /
• v.14 no.4
• /
• pp.81-92
• /
• 2016

Purpose - In recent years, management scholars have expressed growing interest in the concept of person-Job fit because of having many benefits for employees' attitudes and behaviors. The related research is needed to determine what specific types of fit are related to each other, and to get important individual outcomes. Person-job fit of employees in service organization plays an important role in company as well as person in service industry. Person-job fit, representing the consistency between person (service provider) and job (service provided to the customers), gives significant and positive effects on the attitude and behavior of service provider. On the basis of the study background, the purpose of this study is as follows. First, we would like to examine the effects of person-job fit of service provider on their emotional intelligence. Emotional intelligence is divided into four sub-factors such as self-understanding, understanding others, emotional utilization, and emotional regulation. Second, we would like to identify the relationships between job satisfaction and sub-factors such as self-understanding, understanding others, emotional utilization, and emotional regulation. Research design, data, and methodology - We performed structural equation model using Spss 18.0 and Amos 20.0 in order to verify the hypotheses. Subjects were golf service assistants who were high-touching service with high degree in interaction and long contact time with customers. 178 out of the total 200 surveys were used in evaluation from helpers of golf service working as full-time service provider after selecting two locations of golf course located near Busan. From the evaluation of reliability and validity with variables used in this research, they satisfied and confirmed certain standard. Results - The results are as follows. First, as the results of identifying the relationships between person-job fit and emotional intelligence of service provider, person-job fit did not have positive and significant effect on self-understanding. On the other hand, it affected positively and significantly other factors in emotional intelligence such as emotion to others, emotional utilization, and emotional regulation. Second, as the results of identifying the relationship between emotional intelligence and job satisfaction, sub-factors in emotional intelligence such as emotion to others, emotional utilization, and emotional regulation except self-emotion affected significantly and positively job satisfaction. However, self-emotion did not have significant and positive effects on job satisfaction. Conclusion - These results will be valuable and used for service providers. In addition, many service providers will recognize that person-job fit is very important to get a job. This research has a purpose on the assumption that appropriateness between individual and task in service industry shall act as major influence in emotional intelligence of service provider. Recognitive ability of service provider is also very important per characteristics of service, but emotional intelligence that interacts and connected directly with most customers can be a very meaningful factor as well. Emotional intelligence allows people to recognize, understand, and empathize the emotion of customers shall be a positive reinforcement for customers to evaluate the service ultimately.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.27 no.2
• /
• pp.13-18
• /
• 2019

Sewage sludge treatment is increasing every year due to improvement of living and urbanization. However, interest in anaerobic digestion which is one of the recycling technology. There is anaerobic digestion of increasing due to limitations of ocean dumping and final disposal. But, the limit of anaerobic digestion efficiency due to the advanced treatment of sewage has been limited, and studies for solubilization technology have been actively conducted. Therefore, in this study, we aimed to investigate the variation of generation of scum and the solubilization efficiency in the application of pre-treatment of ozone reaction and the change of properties of digested sludge with wet milling. There are results of VS/TS increased by 4.4% and $SCOD_{cr}/TCOD_{cr}$ increased by 9.4% by wet milling alone. In addition, the increase of the specific surface area due to which the reduction of the particle size of the solid content of the sludge in the ozone reaction caused by wet milling decreased the generation rate of scum at 14.3% and increased VS/TS at 2.1%, compared with the ozone reaction alone. From these results, it is expected that the application of wet milling can be increased the contact efficiency with solids in the sludge during ozone reaction with suppress scum and increase the efficiency of the subsequent process in anaerobic digestion.

• Korean Journal of Materials Research
• /
• v.28 no.11
• /
• pp.659-662
• /
• 2018

We report the properties of infrared photodetectors based on two kinds of quantum dots(QDs): i) 2.0 ML InAs QDs by the Stranski-Krastanov growth mode(SK QDs) and ii) sub-monolayer QDs by $4{\times}[0.3ML/1nm\;In_{0.15}Ga_{0.85}As]$ deposition(SML QDs). The QD infrared photodetector(QDIP) structure of $n^+-n^-(QDs)-n^+$ is epitaxially grown on GaAs (100) wafers using molecular-beam epitaxy. Both the bottom and top contact GaAs layers are Si doped at $2{\times}10^{18}/cm^3$. The QD layers are grown with Si doping of $2{\times}10^{17}/cm^3$ and capped by an $In_{0.15}Ga_{0.85}As$ layer at $495^{\circ}C$. The photoluminescence peak(1.24 eV) of the SML QDIP is blue-shifted with respect to that (1.04 eV) of SK QDIPs, suggesting that the electron ground state of SML QDIP is higher than that of the SK QDIP. As a result, the photoresponse regime(${\sim}9-14{\mu}m$) of the SML QDIP is longer than that (${\sim}6-12{\mu}m$) of the SK QDIP. The dark current of the SML QDIP is two orders of magnitude smaller value than that of the SK QDIP because of the inserted $Al_{0.08}Ga_{0.92}As$ layer.

• KEPCO Journal on Electric Power and Energy
• /
• v.5 no.1
• /
• pp.33-38
• /
• 2019

Thermal power generation accounts for the highest percentage of domestic power generation, among which coal-fired boiler generation accounts for the highest percentage. Coal boilers generate harmful substances and fine dust during coal combustion and have a serious effect on air pollution. So, fluidized-bed boilers have been introduced as eco-friendly coal boilers. It uses a fluid medium which affect the combustion temperature of coal. Because of it fluidized-bed boilers emit less pollutants than original one. Water-wall tubes play an important role in this fluidized bed boiler. Due to the fluid medium, the wall damage is more severe than the existing boiler. However, there is no quantitative maintenance technique in Korea yet. Remote field eddy current testing is a non-destructive evaluation technique that is often used for inspection of inner and outer wall of tube. it can inspect with non-contact and high speed. However, it is an inspection that proceeds from inside the pipe, and the water-wall tube is not able to enter the interior. In this study, we designed and simulated an external remote field eddy current sensor suitable for water-wall tube of a fluidized - bed boiler using simulations. By obtaining a signal similar to the existing remote field eddy current test, the criteria for the external remote field eddy current sensor design can be presented.

• Tissue Engineering and Regenerative Medicine
• /
• v.15 no.6
• /
• pp.735-750
• /
• 2018

BACKGROUND: The major challenge of tissue engineering is to develop constructions with suitable properties which would mimic the natural extracellular matrix to induce the proliferation and differentiation of cells. Poly(${\varepsilon}$-caprolactone)-poly(ethylene glycol)-poly(${\varepsilon}$-caprolactone) (PCL-PEG-PCL, PCEC), chitosan (CS), nano-silica ($n-SiO_2$) and nano-hydroxyapatite (n-HA) are biomaterials successfully applied for the preparation of 3D structures appropriate for tissue engineering. METHODS: We evaluated the effect of n-HA and $n-SiO_2$ incorporated PCEC-CS nanofibers on physical properties and osteogenic differentiation of human dental pulp stem cells (hDPSCs). Fourier transform infrared spectroscopy, field emission scanning electron microscope, transmission electron microscope, thermogravimetric analysis, contact angle and mechanical test were applied to evaluate the physicochemical properties of nanofibers. Cell adhesion and proliferation of hDPSCs and their osteoblastic differentiation on nanofibers were assessed using MTT assay, DAPI staining, alizarin red S staining, and QRT-PCR assay. RESULTS: All the samples demonstrated bead-less morphologies with an average diameter in the range of 190-260 nm. The mechanical test studies showed that scaffolds incorporated with n-HA had a higher tensile strength than ones incorporated with $n-SiO_2$. While the hydrophilicity of $n-SiO_2$ incorporated PCEC-CS nanofibers was higher than that of samples enriched with n-HA. Cell adhesion and proliferation studies showed that n-HA incorporated nanofibers were slightly superior to $n-SiO_2$ incorporated ones. Alizarin red S staining and QRT-PCR analysis confirmed the osteogenic differentiation of hDPSCs on PCEC-CS nanofibers incorporated with n-HA and $n-SiO_2$. CONCLUSION: Compared to other groups, PCEC-CS nanofibers incorporated with 15 wt% n-HA were able to support more cell adhesion and differentiation, thus are better candidates for bone tissue engineering applications.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.23 no.2
• /
• pp.93-106
• /
• 2021

In general, segment lining tunnel refers to a tunnel formed by connecting precast concrete segments as a ring and connecting such rings to each other in the longitudinal direction of the tunnel. As the structural properties of the segment lining is highly dependent on the behavior of the segment joints, thus correct modelling of joint behavior is crucial to understand and design the segment tunnel lining. When the tunnel is subjected to ground loads, the segment joint behaves like a hinge that resists rotation, and when the induced moment exceeds a certain limit of the rotation then it may enter into non-linear field. In understanding the effect of the segment joint on the lining behavior, a moment-rotation relationship of the segment joint was explored based on the Japanese practice and Janssen's approach commonly used in the actual design. This study also presents a method to determine the rotational stiffness of joint refer to the bearing strength. The rotation of the segment joint was estimated in virtual design conditions based on the existing models and the proposed method. And the sectional force of the segment lining and joint were calculated along with the estimated rotation. As the rotation at the segment joint increases, the joint contact area decreases, so the designer have to verify the segment joint for bearing strength as well. This paper suggests a consistent method to determine the rotational stiffness and bearing strength of joints.

• Membrane Journal
• /
• v.30 no.6
• /
• pp.443-449
• /
• 2020

In this study, CO2 separation experiment was performed on a CH4/CO2 mixed gas using a ceramic hollow fiber membrane contactor module (HFMC). In order to fabricate high-durability HFMC, a high-durability hollow fiber membrane was prepared and evaluated. HFMC was fabricated using the prepared hollow fiber membrane, and the experiment used a mixture of CH4/CO2 (30% CO2, CH4 balance) and monoethanolamine (MEA). During HFMC operation, the effect of gas and absorbent pressure on the CO2 removal efficiency was evaluated. The CO2 removal efficiency increased as the gas pressure increased, and the CO2 absorption flux also showed a tendency to increase with the liquid flow rate. In addition, when the CO2 absorption rate was less than 40%, LTS-1, a counter-current form where the absorbent enters from the bottom, has higher CO2 removal performance than LTS-2, a countercurrent form in which the absorbent enters from the top. and when the absorption rate was 40% or higher, LTS-2 had higher performance than LTS-1.