• Korea Trade Review
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• v.43 no.3
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• pp.1-26
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• 2018

This study estimates the technical efficiency and total factor productivity(TFP) of and analyzes the relationship between TFP and exports for Korean manufacturing companies from 2000 to 2016. Specially, TFP is decomposed into Technical Change(TC), Technical Efficiency Change (TEC), and Sale Effect(SE), and compared between large and small enterprises. First, in the case of technical efficiency, the Korean economy has been very vulnerable to external shocks, such as the sharp decline following the 2008 financial crisis. The efficiency of the electronics, automobile, and machinery sectors is low and needs to be improved. In addition, the technological efficiency of large enterprises is higher than that of SMEs in most manufacturing sub-sectors except for non-ferrous metals. In the case of TFP, most changes are due to TC, and the effective combination of labor, capital and the effect of scale have little effect, suggesting that improvement of internal structure is urgent. In addition, volatility due to the impact of the financial crisis in 2008 was much larger in SMEs than in large companies, so external economic impacts are more greater for SMEs than large enterprises. The relationship between TFP decomposition factors and exports shows that TC has a positive effect only on exports of SMEs. Therefore, in order to increase exports, in the case of SMEs, R&D support to promote technological development is needed. In the case of large companies, it is necessary to establish differentiated strategies for each export market, competitor company, and item to link efficiency and scale effect of exports.

• Korea Science and Art Forum
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• v.31
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• pp.355-365
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• 2017

The future population of Korea is expected to reach the second highest level in the world by 2060 for the elderly. It is because of the rapid development of low fertility and medical technology. The burden of society for the elderly is expected to increase steadily. The elderly person firstly appears functional disorder. They have low ability in memory and in cognitive will be. Their activities are therefore limited. And economic production capacity is sharply reduced. Self-sufficiency is a difficult situation. They need help in economic and social aspects. Products for them need research and development. The elderly have a Mild Cognitive Impairment(MCI) stage with poor cognitive abilities. It is effective to combine pharmacological and non-pharmacological treatment methods for people with mild cognitive impairment. The effects of non-pharmacological treatments on music have been proven. This paper is a study on the appearance from the viewpoint of design in the development of ancillary instruments using music therapy techniques with Digital Convergence. For this study, we investigated the preference for external appearance of mild cognitive impairment. Two times surveys were conducted. As a result, the design of home care product for the hard cognitive impaired was different from that of a conventional game machine or set top box. It should be designed according to the user's special circumstances. They are memory and cognitive abilities. Products that meet physical and mental changes must be developed.

• Resources Recycling
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• v.32 no.1
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• pp.21-32
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• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).

• Journal of the Korean Institute of Gas
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• v.27 no.2
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• pp.39-48
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• 2023

This study presents the experimental results to measure the adsorption amount of methane gas by coal according to the conditions of a coalbed methane (CBM) reservoir. Adsorbed gas to coal seam particles was measured under reservoir conditions (normal pressure ~ 1,200 psi pressure range, temperature range15 ~ 45℃) using coal samples obtained from random mines in Kalimantan Island, North Indonesia. The obtained amount of absolute adsorbed gas was applied to triangular with linear interpolation to calculate the maximum amount of adsorbed gas according to temperature and pressure change, at which no experiment was performed. As a result, it was revealed that the amount of adsorbed gas to coal particles increased as the pressure increased and temperature decreased, but the increase of the amount of adsorbed gas decreased at more than an appropriate depth(1,000 ft). In the cleat permeability and cleat porosity for each depth of the coal bed considering the effective stress, the cleat permeability was 28.86 ~ 46.81 md, and the cleat porosity was 0.83 ~ 0.98%. This means that the gas productivity varies significantly with the depth because the reduction of the permeability according to the depth in the coal seam is significant. Therefore, a coalbed depth should be considered essential when designing the spacing of production wells in a coalbed methane reservoir in further study.

• Animal Bioscience
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• v.36 no.10
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• pp.1612-1618
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• 2023

Objective: In our previous study, we observed that the addition of waste cooking oil (WCO) reduced ammonia (NH₃) emissions during laboratory-scale composting of dairy cattle manure under low-aeration condition. Therefore, this study aimed to evaluate the effect of addition of WCO on NH₃ emissions reduction during pilot-scale composting of dairy cattle manure, which is close to the conditions of practical composting treatment. Methods: Composting tests were conducted using pilot-scale composting facilities (1.8 m³ of capacity). The composting mixtures were prepared from manure, sawdust, and WCO. Two treatments were set: without WCO (Control) and with WCO added to 3 wt% of manure (WCO3). Composting was conducted under continuous aeration at 40 L/min, corresponding to 22.2 L/(min·m³) of the mixture at the start of composting. The changes in temperatures, NH₃ concentrations in the exhaust gases, and contents of the composted mixtures were analyzed. Based on these analysis results, the effect of WCO addition on NH₃ emissions and nitrogen loss during composting was evaluated. Results: During composting, the temperature increase of the composting mixture became higher, and the decreases of weight and water content of the mixture became larger in WCO3 than in Control. In the decrease of weight, and the residual weight and water content of the mixture, significant differences (p<0.05) were detected between the two treatments at the end of composting. The NH₃ concentrations in the exhaust gases tended to be lower in WCO3 than in Control. Nitrogen loss was 21.5% lower in WCO3 than in Control. Conclusion: Reduction of NH₃ emissions by the addition of WCO under low aeration condition was observed in pilot-scale composting, as well as in laboratory-scale composting. This result suggests that this method is effective in reducing NH₃ emissions in practical-scale composting.

• Journal of the Korean Society of Food Culture
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• v.23 no.1
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• pp.130-137
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• 2008

If we may practice the nutrition education planned on the basis which carefully grasped the inappropriate behavioral determinants of middle-school students, it might be an effective method achieving the change in perception and behavior improving the distorted perception about the ideal body shape, so we are to suggest the 8 week program of body shape perception improvement for successful nutrition education as follows. The body shape perception improvement program is a step-by-step group consulting program. At the introduction stage, we let them understand the meaning of true beauty and body change of teenage period and forming of sexual identity. At the stage of perception conversion, we let them have the opportunity to observe the status of body perception of the teenager and self-observation. At the stage of correction, we let them criticize the distorted body image in the society with mass media at the same time with the self-reflection. At the stage of maintenance and evaluation, we suggested the behavior guidance while preparing it. Setting this as the basis, we applied the contents such as the evaluations through cultural sharing events making somethings while directly participating. As the target groups to practice education were middle school students, we considered the learning level and behavioral features of the middle school students, and composed the programs including the methods such as role play, watching real things, media production, discussions and experiences. If the program of body shape perception improvement developed at this study could be utilized at the field of schools, the teenagers can change their ways of thought naturally avoiding the view about unified appearance rightly perceiving negative self-image that the teenagers can have and if the group consulting can be practiced regularly at each school, many students may experience the change in perception, so it might solicit the improvement of health of the families and local societies as well as that of the individual student.

• Korean Journal of Plant Resources
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• v.36 no.4
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• pp.264-274
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• 2023

To evaluate functional biomaterials of 5 invasive alien plants, total polyphenol and flavonoid contents, antioxidant activity, anti-inflammatory activity, and antibacterial effect were measured. The total polyphenol and flavonoid contents of the extracts were in the order of Rumex acetosella L. > Hypochaeris radicata L. ≥ Lactuca scariola L. > Humulus japonicus Siebold & Zucc. ≥ Solanum viarum Dunal. The DPPH and ABTS radical scavenging activities of the extract were the highest in R. acetosella and correlated well with the total polyphenol contents. In RAW 264.7 cells stimulated with lipopolysaccharide (LPS), nitric oxide (NO) and prostaglandin E₂ (PGE₂) production inhibitory effect of the extracts (100 ㎍ SE/mL) were 20~60% and 10~70%, respectively, showing the highest inhibitory effect in R. acetocella. The extracts of R. acetosella, H. japonicus and S. viarum showed antibacterial activity against food poisoning-causing microorganisms such as Bacillus subtilis, Escherichia coli, Vibrio parahaemolyticus and Vibrio vulnificus. Furthermore, the H. japonicus extract was found to have effective antibacterial activity against oral microorganisms such as Enterococcus faecalis, Lacticaseibacillus casei, Rothia dentocariosa, Staphylococcus epidermidis and Streptococcus mutans, and its major active ingredients were predicted to be pentadecylic acid, palmitic acid and clionasterol. These results suggest that alien plants have potential as biomaterials with antioxidant, anti-inflammation and antibacterial effects.

• The Plant Pathology Journal
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• v.39 no.1
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• pp.108-122
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• 2023

Fusarium oxysporum f. sp. lycopersici (Fol) and Fusarium oxysporum f. sp. cubense (Foc), are the causal agent of Fusarium wilt disease of tomato and banana, respectively, and cause significant yield losses worldwide. A cost-effective measure, such as biological control agents, was used as an alternative method to control these pathogens. Therefore, in this study, six isolates of the Streptomyces-like colony were isolated from soils and their antagonistic activity against phytopathogenic fungi and plant growth-promoting (PGP) activity were assessed. The results showed that these isolates could inhibit the mycelial growth of Fol and Foc. Among them, isolate STRM304 showed the highest percentage of mycelial growth reduction and broad-spectrum antagonistic activity against all tested fungi. In the pot experiment study, the culture filtrate of isolates STRM103 and STRM104 significantly decreased disease severity and symptoms in Fol inoculated plants. Similarly, the culture filtrate of the STRM304 isolate significantly reduced the severity of the disease and symptoms of the disease in Foc inoculated plants. The PGP activity test presents PGP activities, such as indole acetic acid production, phosphate solubilization, starch hydrolysis, lignin hydrolysis, and cellulase activity. Interestingly, the application of the culture filtrate from all isolates increased the percentage of tomato seed germination and stimulated the growth of tomato plants and banana seedlings, increasing the elongation of the shoot and the root and shoot and root weight compared to the control treatment. Therefore, the isolate STRM103 and STRM104, and STRM304 could be used as biocontrol and PGP agents for tomato and banana, respectively, in sustainable agriculture.

• Journal of the Korean Society of Food Culture
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• v.23 no.5
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• pp.582-594
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• 2008

This study aimed at evaluating current sanitation management performances in Korean-Food restaurants by their operation types and to develop sanitary training posters based on the risk factors, in an attempt to improve the level of sanitation management in Korean food service facilities. Eighteen Korean-food restaurants that are managed by franchisor, franchisees as well as self-managed with large-scale and small-scale restaurants in Seoul and Gyeonggi-Do, were evaluated by on-the-spot inspectors with an auditing tool consisting of three dimensions, nine categories and thirty four items. Data were analyzed using SPSS. The total score of each group showed that restaurants managed by franchisees ranked the highest (59 out of 100 points), while self-managed, small-scale restaurants ranked the lowest (44 out of 100 points). In the categorization of sanitation management compliance, the dimensions of food hygiene during production recorded the lowest compliance rate of 47.7% (22.89/48.0 points) followed by the dimension of environmental hygiene 59.3% (20.17/34.0 points) and personal hygiene 60.5% (10.89/18.0 points). This indicated the need for urgent improvement. The items which showed the lowest compliance rates were 'proper thawing of frozen foods' (0%), 'notifying and observing heating/reheating temperature' (6%), 'using of hand-washing facility and proper hand-washing' (33%), 'monitoring temperature of frozen-foods and cold-foods' (35%), and 'prevention of cross-contamination' (36%) among thirty four items. Self-managed, small-scale restaurants, in particular, needed to improve sanitary practices such as 'sanitation education for employee', 'verifying the employee health inspection reports', 'storing food on the shelves 15 cm distance away from the wall', 'suitability of ventilation capacity of hoods' and 'cleanliness of drainage'. On the basis of the findings of this study, we developed sanitary training posters, especially for small-scale restaurant operators. This could be an effective tool to educate food service employees on sanitary knowledge and principles and could be used to improve the existing sanitary conditions in Korean food service facilities.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.276-279
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• 2022

The 4th industrial revolution refers to the transition to a knowledge society in which the production speed of knowledge is fast and the proportion of the knowledge industry is greatly increased. The reorganization of the industrial structure and the change of occupations and jobs due to new technologies are bringing about changes in education, and the development of digital technology has made education that is borderless, individual and dynamic, becoming the new standard of education. With these changes, interest in nano-degrees on new technologies or micro-degrees focused on core courses rather than regular course degrees is increasing. As a representative example, Udacity in the United States has opened and operated online nanodegree courses related to jobs, and collaborates with major companies to develop and educate core training courses necessary for companies, thereby efficiently supporting companies in securing talent. With the revitalization of online vocational and job training, an environment has been prepared in which individuals can set goals for vocational competency development and continue their portfolio-based sustainable learning. However, for effective vocational education, automated and personalized educational content design should be preceded. To this end, in this paper, we propose a personalized career and course map recommendation system in the era of online learning