• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1310-1320
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• 2020

Low-quality soil for land reuse is a crucial problem in vegetation quality and especially to waste disposal sites in mining areas. It is necessary to find suitable materials to improve the soil quality and especially to increase soil microbial diversity and activity. In this study, pot experiments were conducted to investigate the effect of a mixed material of humic acid, super absorbent polymer and biochar on low-quality soil indexes and the microbial community response. The indexes included soil physicochemical properties and the corresponding plant growth. The results showed that the mixed material could improve chemical properties and physical structure of soil by increasing the bulk density, porosity, macro aggregate, and promote the mineralization of nutrient elements in soil. The best performance was achieved by adding 3 g·kg^-1 super absorbent polymer, 3 g·kg^-1 humic acid, and 10 g·kg^-1 biochar to soil with plant total nitrogen, dry weight and height increased by 85.18%, 266.41% and 74.06%, respectively. Physicochemical properties caused changes in soil microbial diversity. Acidobacteria, Bacteroidetes, Chloroflexi, Cyanobacteria, Firmicutes, Nitrospirae, Planctomycetes, and Proteobacteria were significantly positively correlated with most of the physical, chemical and plant indicators. Actinobacteria and Armatimonadetes were significantly negatively correlated with most measurement factors. Therefore, this study can contribute to improving the understanding of low-quality soil and how it affects soil microbial functions and sustainability.

• Journal of Biosystems Engineering
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• v.9 no.2
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• pp.65-73
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• 1984

While most of researches on the performance of high temperature grain dryer have dealt mainly with improving dryer capacity and drying speed during the last twenty years, energy efficiency, in fact, has not been emphasized. Current fuel supplies and energy cost have shifted the emphasis to reducing the energy consumption for grain drying while maintaining dryer capacity and grain quality. Since the energy input for drying is relatively large, the recovery and reuse of at least part of the exhaust energy can significantly reduce the total energy consumption in existing drying systems. Unilization of exhaust heat in grain dryer either through direct recycling or by a thermal coupling in heat exchanger have been subject of a number of investigators. However, very seldom research in Korea has been done in this area. Three drying tests(non-recycling, 0.22 recycle ratio, and 0.76 recycle ratio)were performed to investigate the thermal efficiency and heat loss factors of continuous flow type dryer, and to analyze the effect of recycle ratio (weight of exhaust air recycled/total weight of input air) on the energy requriements for rough rice drying. The test results showed that when the exhaust air was not recycled, the energy lost from furnace was 15.3 percent of input fuel energy, and latent and sensible heat of exhaust air were 61.4 percent and 11.2 percent respectively. The heat which was required in raising grain temperature and stored in dryer was relatively small. As the recycle ratio of exhaust air was increased, the drying rate was suddenly decreased, and thermal efficiency of the kerosene burner was also decreased. Drying test with 0.76 recycle ratio resulted in 12.4% increase in fuel consumption, and 38.4% increase in electric power consumption as compared to the non-recycled drying test. Drying test of 0.22 recycle ratio resulted in 6.8% saving in total energy consumption, 8.0% reduction in fuel consumption, and 2.5% increase in electric power consumption as compared to the non-recycled drying test.

• Safety and Health at Work
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• v.9 no.1
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• pp.53-58
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• 2018

Background: Since the Republic of Korea became a labor-force-importing country, the number of foreign workers has increased gradually, especially in the construction industry. The main objective of this study was to examine the differences in safety perception between domestic and foreign workers at Korean construction sites. Methods: A total of 891 Korean and foreign workers were surveyed: 140 foreign and 751 Korean workers. The general characteristics and 25 factors influencing safety perception were considered in the questionnaire. Regression and correlation analyses were conducted to examine the variables of workers' safety perception. Results: Differences of nationality (F = 7.379, p < 0.001) and workplace accidents were statistically significant for both domestic (F = 1.503, p < 0.05) and foreign workers (F = 7.868, p < 0.05). In contrast, age, education, and Korean language level were significant variables only for foreign workers. Correlation coefficients of $0.428^{**}$ for Korean and 0.148 for foreign workers between two items - namely, "management's commitment to safety" and "blaming staff when they make mistakes" - support the conclusion that foreign workers do not trust management's commitment to safety, while Korean workers have confidence in these commitments. Conclusion: Foreign workers' level of safety perception should rise to the same level as Korean workers, especially in terms of obeying safety rules, safety education performance, and safety beliefs. Therefore, an improvement plan for the Korean construction industry is suggested in order to have a better safety level at construction sites with foreign workers.

• Korean Journal of Construction Engineering and Management
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• v.21 no.5
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• pp.46-54
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• 2020

The construction industry has the most safety accidents among domestic industries. Special care must be taken because disasters in the construction industry lead to social problems caused by huge property losses and casualties. As a result of this, there is a growing awareness of disasters occurring in the construction industry, and government departments are tightening regulations on safety management. In particular, the OSHA (Occupational Safety and Health Agency) focuses on the expansion of protection targets and the clarification of responsibility in the full amendment OSHA. As a result, a study that focuses on safety management by client's responsibility is needed. In this study, the project performance capability assessment of construction project management contractors, which is being carried out with uniform assessment criteria without considering the characteristics of the construction project, is considered and all the amendments to the OSHA are considered, and the factors were derived for improvement measures.

• Journal of Korean language education
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• v.28 no.4
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• pp.63-86
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• 2017

This research aims to evaluate the effects and the shortcomings of strategies for teaching paraphrasing to foreign university students. For this study, the effects of teaching paraphrasing skills on student's academic writing was investigated through the assessment of pre- and post-test writing tasks and through a focus group interview. The teaching of paraphrasing was divided into 3 instructional sessions and the focus group interview was conducted at the end of the last session. After each instructional session three trained assessors evaluated the outcomes of pre and post task writings; the in-depth focus group interviews were conducted on seven of the students in order to define better positive effects as well as shortcomings. By comparing the scores of pre- and post-task assignments it is possible to affirm that there is a meaningful difference for overall scores; moreover, in an analysis conducted on each single sub-element of the paraphrasing skill, it emerged that except for "task completion", all other four elements of "structure", "understanding core content", "change of expression" and "academic expressions" showed a statistically significant improvement in performance. On the other hand, as a result of the focus group interview, it was possible to individuate as main shortcomings insufficient vocabulary knowledge, poor overall comprehension of the reference material, lack of practice and difficulty in connect sentences organically. It is possible to consider these elements as limiting factors in understanding the reference material and making correct citations by the students. Therefore, we suggest as supplementary instructional strategies a deeper attention to the difficulty level of the text, the introduction of devices to understand better the content of the reference material and an integrated practice of the paraphrasing skill.

• Journal of the Korean Society for Railway
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• v.16 no.3
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• pp.233-239
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• 2013

This paper studied the stress of Metropolitan Transit driving crews. Stress to such workers can not only lead to fatalities and infrastructure damage but also enormous loss of competitiveness. The study was carried out to search for ways of alleviating stress of driving crews. In order to reduce the various factors that exacerbate job stress of driving crews of Metropolitan Transit, it is first necessary to expand training in order to enhance their expertise, and improve facilities to protect driving crews in the event of accidents. Second, psychological compensation or organization's systems may cause job stress. It may therefore be possible to solve fundamental problems through typical organization level approach such as leadership training programs. Third, job stress may be reduced through proper life habits such as personal regular exercise. Fourth, we need to improve driving crews' working conditions and adjust working hours by avoiding excessive performance competition and an unfair evaluation system, by understanding their mental states, and by setting up systems such as a comprehensive health improvement and management program at the organization level.

• Journal of Digital Convergence
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• v.17 no.7
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• pp.369-376
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• 2019

This study aimed to identify the relationship between perfectionism and motivational climate in competitive athletes and to provide information for improvement of their performance. One hundred ninety-six athletes who trained in Korea National Training Center participated in this study and they were divided into record and man-to-man events. Also they filled in the questionnaire about demographic factors, perfectionism, and motivational climate. Collected data were analyzed by using cross validation and independent t-test for identifying the difference of two events and structural equation model for testing hypotheses and model fit. Perfectionism and motivational climate in man-to-man events were stronger compared to record event. In record event, perfectionism was more influenced by ego involving motivational climate compared to task involving, while in man-to-man event, perfectionism was affected by only ego involving motivational climate. However, these both study models had a bad fit.

• Geomechanics and Engineering
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• v.17 no.4
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• pp.367-374
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• 2019

This study concluded the results of a research on the features of cement based permeation grout, based on some important grout parameters, such as the rheological properties (yield stress and viscosity), coefficient of permeability to grout ($k_G$) and the inject ability of cement grout (N and $N_c$ assessment), which govern the performance of cement based permeation grouting in porous media. Due to the limited knowledge of these important grout parameters and other influencing factors (filtration pressure, rate and time of injection and the grout volume) used in the field work, the application of cement based permeation grouting is still largely a trial and error process in the current practice, especially in the local construction industry. It is seen possible to use simple formulas in order to select the injection parameters and to evaluate their inter-relationship, as well as to optimize injection spacing and times with respect to injection source dimensions and in-situ permeability. The validity of spherical and cylindrical flow model was not verified by any past research works covered in the literature review. Therefore, a theoretical investigation including grout flow models and significant grout parameters for the design of permeation grouting was conducted in this study. This two grout flow models were applied for three grout mixes prepared for w/c=0.75, w/c=1.00 and w/c=1.25 in this study. The relations between injection times, radius, pump pressure and flow rate for both flow models were investigated and the results were presented. Furthermore, in order to investigate these two flow model, some rheological properties of the grout mixes, particle size distribution of the cement used in this study and some geotechnical properties of the sand used in this work were defined and presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.6
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• pp.1195-1204
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• 2021

In this paper, we present an optimal design method for wave power generators using the response surface analysis. Especially, in our method, we reduce the mechanical loss by selecting the linear generator whose linear movement can be converted to the electrical energy directly with the vertical movement of waves. Therefore, we calculate the exciting force acting on the drive device in a slow-wave condition and determine the winding process with a ratio of the slots and poles for the improvement of energy conversion efficiency. In addition, we employ the regression analysis for deriving the shape factors of the stator and the translator, which have a significant effect on the performance of a generator. We choose the best design variables through the response surface analysis, and then we study the optimization method for designing the efficient experiment using the analysis results. Finally, we show the validity of the proposed method through the simulation results.

• Journal of Korean Society of Rural Planning
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• v.28 no.2
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• pp.21-32
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• 2022

Since the village maintenance type public housing project was introduced in 2015, the resident needs for regional revitalization and pleasant living conditions are not being met due to the poor performance of the public housing complexes that reflect the surrounding area maintenance plan (village plan) and regional characteristics. The purpose of this study is to suggest a plan to revitalize the village maintenance type public housing project in consideration of regional characteristics as a result of analyzing the needs of local residents through the problems of the village maintenance type public housing project being promoted so far and resident satisfaction. As a result of the analysis based on the public housing project implementation status analysis and resident satisfaction, the plans to activate the village maintenance type public housing project are as follows. First, in order to secure the effectiveness of the village plan, it is desirable to promote the public housing project and the village plan at the same time. It is necessary to secure a budget according to the selection of public offering projects in the village plan, such as promoting public housing projects without setbacks by prioritizing land purchases for public housing sites and establishing specialized strategies considering regional characteristics. Second, a public housing project that responds to local demand is required. The evaluation factors such as continuous promotion of the urban architecture integration plan and strengthening of regional linkage plans such as specialization of regionally tailored designs should be supplemented so that regional resources and village plans are linked with the public housing specialization plan. Third, surrounding area maintenance plan (village plan) should be secured by the strengthen of the legal status or establishing related provisions. It is also necessary to promote system improvement for area maintenance plan (village plan) when selecting a publicly funded public project.