• Food Science of Animal Resources
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• v.39 no.5
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• pp.844-861
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• 2019

Over the last few years, marine environment was found to be a source of surplus natural products and microorganisms with new bioactive secondary metabolites of interest which can divulge nutritional and biological impact on the host. This study aims to assess the possible, inherent and functional probiotic properties of a novel probiotic strain Enterococcus durans F3 (E. durans F3) isolated from the gut of fresh water fish Catla catla. Parameters for evaluating and describing the probiotics described in FAD/WHO guidelines were followed. E. durans F3 demonstrated affirmative results including simulated bile, acid and gastric juice tolerance with exhibited significant bactericidal effect against pathogens Staphylococcus aureus, Salmonella Typhi, Escherichia coli and Pseudomonas aeruginosa. This can be due to the enterocin produced by E. durans F3 strain, which was resolute by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) gel with amplification of the anticipated fragment of a structural gene; enterocin A, followed by antibiotic susceptibility assessment. Effective antioxidant potentiality against ${\alpha}$-diphenyl-${\alpha}$-picrylhydrazyl free radicals including lipase, bile salt hydrolase activity with auto-aggregation and cell surface hydrophobicity was similarly observed. Results are proving the potentiality of E. durans F3, which can also be used as probiotic starter culture in dairy industries for manufacturing new products that imparts health benefits to the host. Finding the potent and novel probiotic strains will also satisfy the current developing market demand for probiotics.

• Elastomers and Composites
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• v.15 no.3
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• pp.147-154
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• 1980

The cellular rubber products for industrial purpose have been applied in many fields such as auto-motive parts, ship-building, machinery, sports goods, diving suit or interior housings etc. The purpose of this dissertation is to study the physical properties of celluar rubber products particulary for those elastomers such as EPDM, CR and NBR with heat resistance property, weather proofness, and oil resistance characteristics respectively, aiming at improving their quality, and renovating the manufacturing know-how which is beyond our technical power at the present time in Korea. In order to meet this requirement an ideal recipe is being shown for the three elastomers, and also a practical recipe which is easily available in terms of compounding ingredients in domestic market has set up as shown in Table 1. for the investigation of vulcanization characteristics by means of Rheometer. The optimum Mooney viscosity of compounded rubber was found to be approximately $ML_{1+4}(100^{\circ}C)$ $30\sim45$. Excess mustication makes a dispersion of ingredients worse, consequently it causes deformation of shapes and heterogenous cell distribution. In other words the articles are rejected because of its insufficient workmanship. The results of physical properties of the products are indicated in Table 3. It has shown that the quality meet requirement when tested in accordance with ASTM D572, 573 and D 395. The test results o CR/IR blends in terms of hardness, volume change by blowing, tensile strength and elongation have been shown.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.2
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• pp.137-142
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• 2021

A Photovoltaic power streetlight is a system that uses solar energy to charge a secondary battery and then uses it for night lighting through a lamp, and can be configured as a standalone or grid-connected type by installing an LED streetlight at the load end. The energy generated through the solar cell module can be charged to the secondary battery through the charge/discharge control device, and then the LED street light can be turned on and off by comparing the power generation voltage and the charging voltage according to the monitoring of solar radiation, or by setting a specific time after sunset or sunrise. Based on these contents, this paper designed and manufactured a simulated solar power streetlight for education using new and renewable energy utilization and storage functions. Using these educational equipment, students can 1) understand the flow of energy change using renewable energy including sunlight as electric energy, 2) understand new and renewable energy, and cultivate basic design and manufacturing application power of related products, 3) The use of new and renewable energy through power conversion and strengthening of practical training and analysis through hardware production can be instilled.

• Journal of Digital Convergence
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• v.19 no.11
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• pp.301-313
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• 2021

The automotive industry is facing a paradigm shift, changing from owning to sharing and from manufacturing to service. However, it is hard to conclude that the economic value of smart mobility service is always positive to users. Cost related to owing or share a vehicle is very hard to estimate from the perspective of potential users as well as the benefit of the service. Focusing on the cost side of the story, this study develops a cost estimating model based on three main factors: electrification, advanced driving assistant systems (ADAS) function, and participation of ride-sharing service. As a result of the model analysis, low cost was estimated as a result when receiving cost benefits such as electrification and ride-sharing participation. Various factors were analyzed through sensitivity analysis also. These results can provide useful insights into the cost prediction and strategies for potential users and manufacturers on smart mobility service market.

• Clean Technology
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• v.28 no.2
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• pp.97-102
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• 2022

Lithium sulfur (Li-S) batteries have attracted considerable attention as a promising candidate for next-generation power sources due to their high theoretical energy density, low cost, and eco-friendliness. However, the poor electrical conductivity of sulfur and its insoluble discharging products (Li₂S₂/Li₂S), large volume changes, severe self-discharge, and dissolution of lithium polysulfide intermediates result in rapid capacity fading, low Coulombic efficiency, and safety risks, hindering Li-S battery commercial development. In this study, a three-dimensionally (3D) connected hierarchical porous carbon framework (HPCF) derived from waste sunflower seed shells was synthesized as a sulfur host for Li-S batteries via a chemical activation method. The natural 3D connected structure of the HPCF, originating from the raw material, can effectively enhance the conductivity and accessibility of the electrolyte, accelerating the Li⁺/electron transfer. Additionally, the generated micropores of the HPCF, originated from the chemical activation process, can prevent polysulfide dissolution due to the limited space, thereby improving the electrochemical performance and cycling stability. The HPCF/S cell shows a superior capacity retention of 540 mA h g^-1 after 70 cycles at 0.1 C, and an excellent cycling stability at 2 C for 700 cycles. This study provides a potential biomass-derived material for low-cost long-life Li-S batteries.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.4
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• pp.512-519
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• 2023

Pacific oysters Crassostrea gigas are a popular shellfish in the Republic of Korea. However, due to their abundant moisture and nutrient content, oysters are susceptible to microbiological growth and biochemical changes, which lead to quality degradation. Therefore, the present study aimed to investigate the effectiveness of modified atmosphere packaging (MAP) in maintaining the quality of raw oysters during storage. Microbiological and physicochemical parameters such as pH, glycogen content, soluble protein, turbidity, and volatile basic nitrogen (VBN) were analyzed for oysters stored under various gas compositions and storage periods. The results showed that there was no significant increase in viable cell count in MAP oysters after six days in MAP oysters. Moreover, the physicochemical quality of non-MAP oysters deteriorated rapidly, whereas the quality of MAP oysters were maintained during storage. This study suggests that MAP can be an effective technique for maintaining the freshness of raw oysters during distribution and storage, and may also be useful for extending the shelf-life and maintaining the quality of other seafood products.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.4
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• pp.332-340
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• 2023

Crystalline silicon solar cells have attracted great attention for their various advantages, such as the availability of raw materials, high-efficiency potential, and well-established processing sequence. Tunnel oxide passivated contact (TOPCon) solar cells are widely regarded as one of the most prospective candidates for the next generation of high-performance solar cells because an efficiency of 26% has been achieved in small-area solar cells. Compared to n-type TOPCon solar cells, the photo conversion efficiency (PCE) of p-type TOPCon is slightly higher. The highest PCEs of p-type TOPCon and n-type TOPCon solar cells are 26.0% and 25.8%, respectively. Despite the highest efficiency in small-area cells, limited progress has been achieved in p-type TOPCon solar cells for large are due to their lower carrier lifetime and inferior surface passivation with the boron-doped c-Si wafer. Nevertheless, it is of great importance to promoting the p-type TOPCon technology due to its lower price and well-established manufacturing procedures with slight modifications in the PERC solar cells production lines. The progress in different approaches to increase the efficiencies of p-type TOPCon solar cells has been reported in this review article and is expected to set valuable strategies to promote the passivation technology of p-type TOPCon, which could further increase the efficiency of TOPCon solar cells.

• Current Photovoltaic Research
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• v.11 no.2
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• pp.44-48
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• 2023

In heterojunction technology (HJT) solar cells, low-temperature curing paste is used because the passivation layer deteriorates at high temperatures of 200℃ or higher. However, manufacturing HJT photovoltaic (PV) modules is challenging due to the weak peel strength between busbar electrodes and cells after soldering process. For this issue, the electrode thicknesses of the busbars of the HJT solar cell were analyzed, and the peel strengths between electrodes and wires were measured after soldering using an infrared (IR) lamp. As a result, the electrodes printed by the screen printing method had a difference in thickness due to screen mask. Also, as the thickness of the electrode increased, the peel strength of the wire increased.

• Journal of Hydrogen and New Energy
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• v.34 no.6
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• pp.673-681
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• 2023

Hydrocarbon-based polymer membranes to replace perfluorinated polymer membranes are being continuously researched. However, hydrocarbon-based membranes have a problem in that they are less durable than fluorine-based membranes. In this study, we sought to compare the annealing effect to improve the durability of sulfonated poly(ether ether ketone) (SPEEK). After membranes formation, thermogravimetric analysis and tensile strength were measured to compare changes in membranes properties due to annealing. After manufacturing the membrane and electrode assembly (MEA), the initial performance and chemical durability was compared with unit cell operation. During the 24-hour annealing process, the strength increased due to the increase in-S-O-S-crosslinking, and the sulfonic acid group decreased, leading to a decrease in I-V performance. By annealing, the hydrogen permeability was reduced to less than 1/10 of that of the nafion membrane, and as a result, open circuit voltage (OCV) and durability was improved. The SPEEK membranes annealed for 24 hours showed higher durability than the nafion 211 membranes of the same thickness.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.6
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• pp.810-817
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• 2023

Oysters are a highly consumed seafood throughout Korea, but they have a short shelf life because they support rapid microbial growth due to their of high moisture content and fragile muscle tissue. We examined natural food additives including lactic acid bacteria fermentation powder, rosemary extract, and lemon juice for their ability to preserve raw oyster Crassostrea gigas quality. Samples were stored at 4℃, and microbiological and physicochemical analyses were conducted. Among the natural additives tested, lemon juice was the most effective. Lemon juice was thus applied at different concentrations (50-300 ppm) to quantitatively assess its effect on total viable cell count, pH, glycogen, soluble protein, and turbidity. 200 ppm was confirmed to be optimal, and is projected to extend shelf life by 2 days compared to the control group.