• Communications of Mathematical Education
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• v.35 no.2
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• pp.173-191
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• 2021

This study noted that a survey of teachers in a leading study conducted in Korea during the Pandemics period pointed out that the "real-time interactive" classes account for a significantly small portion of the remote class format. Contentually, the study reported cases of developing and applying "real-time interactive" class materials based on "planar decision requirements" of high school mathematics subject geometry. The teacher who participated in the development was a math teacher who worked at a Seoul-based high school with 28 years of high school teaching experience, and a teacher who was in charge of geometry in the math department in 2020. The development teacher decided to develop real-time interactive classes. In particular, the materials were developed by organizing the class guidance plan in four stages: 'Meeting and Class Guidance', 'Giving motivation', 'Suggesting tasks', 'Individual Investigative Activities and Teacher Feedback' and 'Reflection and Evaluation' which were selected through the process of selecting the class contents and selecting online class tools. At this time, the development teacher produced and presented about five minutes of video material using the videooscribe, a whiteboard animation program. And in case of task number 8, it consisted of recording the students' free thoughts after class, which served as a role of assessment by students themselves and providing feedback to their teachers. This study is a case study that introduces a series of courses in which field teachers develop class materials, and in addition to presenting class materials that can be applied directly to classes, is a result of a study that focuses on the role of presenting samples for future class data development. The materials developed were verified as class materials based on the opinions of the students who participated in the class and the results of the evaluation commissioned by the three math teachers.

• Korean Journal of Environmental Biology
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• v.39 no.1
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• pp.46-54
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• 2021

The seasonal and vertical biomass of marine forest seaweeds were examined to select a suitable species at 12 sites of the South Sea in Korea between 2018 and 2019. The Habitat Suitability Index (HSI) was also calculated in terms of biomass for six species (three kelp and three Sargassum species). A total of 16 marine forest-forming species including four kelp and 12 Sargassum species were observed at the 12 sites. The average annual seaweed biomass by season and depth ranged from 843.73-2,925.85 g wet wt. m^-2 at the eastern South Sea and from 343.87-4,580.10 g wet wt. m^-2 at the western South Sea. In the kelp species, the Ecklonia cava biomass was predominant, followed by E. stolonifera. The macroalgal species with the greatest biomass was Sargassum macrocarpum, followed by S. horneri. The HSI values of E. stolonifera were between 0.76-1.0 at eight sites and those of E. cava were 0.58-0.92 at four sites, indicating that E. stolonifera was more suitable than E. cava. In the HSI values of the Sargassum species, S. horneri ranged between 0.84-1.0 at all 12 sites and the S. macrocarpum values were between 0.68-0.99. The results indicate that E. cava and S. macrocarpum were the most suitable for the marine forest construction in terms of the seaweed biomass, and E. stolonifera and S. horneri in terms of the HSI values. Thus, we suggest that seaweed biomass and HSI values should be considered when choosing suitable forest-forming species.

• Journal of Food Hygiene and Safety
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• v.36 no.3
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• pp.264-270
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• 2021

In this study we investigated the elution level of lead (Pb), cadmium (Cd), arsenic (As), zinc (Zn), nickel (Ni), antimony (Sb), germanium (Ge), aluminum (Al) and hexavalent chromium (Cr⁶⁺) from 69 home-cooking utensils into a food stimulants. The results of migration testing according to the Korea standards and specifications for utensils, containers and packages showed values the allowable migrantion limits. Al was detected in all 7 utensil materials with the average concentration ranging from 0.002-5.989 mg/L. According to the migration conditions for (180℃, 30 min), the average concentration of Al in paper was 7.2 times higher than 25℃, 10 min (P<0.05). The results of migration testing at 180℃, 30 min were also below the allowable migrantion limits. When comparing with the provisional tolerable weekly intake (PTWI) of Al, the estimated weekly intakes (EWI) accounted for 0.000-0.045% for Al.

• Journal of Life Science
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• v.31 no.5
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• pp.511-519
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• 2021

The Perilla frutescens var. japonica HARA is widely cultivated in Korea for vegetable leaves and oil seeds. Perilla species have been used for food and medicine and are known to contain many functional compounds. In this study, we investigated the functional compound contents of Perilla during its growth stages to analyze the optimal harvest time and conditions. The contents of the Perilla sprouts were analyzed according to culture environment and days of growth. Sprouts grown in soil under natural light conditions showed high rosmarinic acid (23.19±0.16 mg/g) and GABA (0.55±0.05 mg/g) content. Therefore, the results suggest that 6 to 8 days after sowing in soil under natural light conditions was the optimum harvest condition for sprouts. Also, the functional compounds of Perilla were analyzed according to growth stage and plant part. As a result, caffeic acid and rosmarinic acid exhibited the highest content in the stage from vegetative growth to reproductive growth (0.28±0.03 ~ 0.30±0.07 mg/g rosmarinic acid and 20.60±7.02 ~ 19.37±3.18 mg/g caffeic acid), and luteolin and GABA showed the highest content in the reproductive growth stage and in the early stages of vegetative growth, respectively (31.11±2.98 ~ 22.35±1.64 ㎍/g luteolin and 0.42±0.09 ~ 0.37±0.04 mg/g GABA). It was confirmed that the content of caffeic acid (0.34±0.03 mg/g), rosmarinic acid (55.22±9.33 mg/g) and luteolin (1,044.89±6.72 ㎍/g) was the highest during the bolting stage. Overall, we identified the timing of the highest level of functional compounds in the sprouts and mature leaves of Perilla. These results suggest a suitable harvest time and conditions for sprouts and leaves for the use of Perilla as a functional material.

• Journal of Korean Elementary Science Education
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• v.40 no.2
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• pp.239-252
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• 2021

The purpose of this study is to develop an evolutionary STEAM education program based on the brain and to analyze its effects on scientific interest and scientific creativity of elementary school students. Four different topics based on four scientific fields (Physics, Chemistry, Biology and Earth Science) were derived from the science textbook under the 2015 revised curriculum to build a brain-based evolutionary STEAM education program. The research subjects were 90 fourth graders of S-elementary school located in Gyeonggi Province, Korea and they were divided into an experimental group of 45 students and a comparative group of 45 students. The main findings of this study are as follows. First, according to the independent samples t-test of scientific interest, no statistically significant difference were found between the two groups, but the brain-based evolutionary STEAM education had meaningful effect on improving 'interest in scientific learning' and 'anxiety about scientific learning'. Second, according to the paired samples t-test of scientific interest, the experimental group had significantly improved 'interest in science' but on the other hand, there was no effect on the comparative group. Third, scientific creativity and originality of the experimental group were significantly higher after the class than that of the comparative group. Fourth, although there were some significant differences between the two groups in scientific creativity after the class, both groups had improved scientific creativity between the results of pre and post test. Based on these results, we discuss implications for science education and STEAM education research.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.223-236
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• 2021

This study aims to provide basic data for the systematic conservation and efficient management of forest ecosystems by analyzing changes in understory vegetation of temperate broad-leaved deciduous forests. One-hectare permanent survey plot, consisting of 100 subplots sized 10 × 10 meters, was installed in Gwangneung forest in Pocheon, Gyeonggi-do in 2003. The state of stands and the understory vegetation in the permanent survey plot were examined at a 5-year interval from 2003 to 2018. The vascular plants found in the survey area were 56 families, 128 genera, 176 species, 18 variants, 4 varieties, and 1 subspecies, for a total of 199 taxa. The number of species in both the shrub layer and the herbaceous layer showed a tendency to decrease with time. The MRPP-tests showed a significantly differing species composition of the shrub layer in all years except 2008-2013, whereas significant differences were found in all years concerning the herbaceous layer. As for the average importance value, Euonymus oxyphyllus (18.23%), Acer pseudosieboldianum (16.48%), and Callicarpa japonica (13.85%) were dominant in the shrub layer, while Ainsliaea acerifolia (23.41%), Disporum smilacinum (9.45%), and Oplismenus undulatifolius (5.62%) were dominant in the herbaceous layer. In the shrub layer, the richness of Smilax china, Lonicera subsessilis, and Philadelphus schrenkii was high when the basal area and the stand density of an upper layer were high. By contrast, smaller basal area and stand density were associated with the richness of Acer pseudosieboldianum, Deutzia glabrata, Morus bombycis, and Cornus kousa. Furthermore, it was found out that the impact of the basal area and the stand density on the herbaceous layer decreased over time, while the herb layer's species composition was greatly affected by cover degrees of Euonymus oxyphyllus and Acer pseudosieboldianum in the shrub layer. In conclusion, the number of species in the understory vegetation in Gwangneung forest is continuously decreasing, thus implying that species diversity, basal area, and stand density of an upper layer can influence the species composition in understory vegetation.

• Journal of Internet of Things and Convergence
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• v.7 no.2
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• pp.55-63
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• 2021

The purpose of this study was to investigate the structural relationship between the use motives of the Internet of Things (IoT), which was presented as a technology strategy priority for university students, on usage attitudes, usability performance and life satisfaction. From April 1 to April 30, 2021, a non-face-to-face survey was conducted targeting university students living in Gwangju Metropolitan City and Jeollanam-do, and the study was conducted in a total of 213 copies. The collected questionnaires were analyzed using IBM's SPSS 21.0 and AMOS 21.0 programs. The research results are as follows. First, the motivation for using IoT was found to have an effect on usage attitude, and it was found to have an effect on life satisfaction and also on usage performance. Second, it was found that the attitude of using the Internet of Things had an effect on the usability performance. However, it was found that there was no effect on life satisfaction. Third, it was found that the use of IoT has an effect on the life satisfaction of college students. Fourth, it was found that the indirect effect on the attitude of use had an indirect effect on the relationship between the motivation for use and the performance of use. However, it was found that there was no indirect effect on the relationship between use motivation and life satisfaction. Fifth, the indirect effect on the usability performance was found to have an indirect effect on the relationship between use motivation and life satisfaction, Also, it was found that there was an indirect effect on the relationship between usage attitude and life satisfaction. Sixth, in the relationship between use motivation and life satisfaction, there was no double indirect effect via use attitude and utilization performance. Based on these results, the motivation for using the Internet of Things for college students and a solution to the information gap were proposed.

• Knowledge Management Research
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• v.22 no.2
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• pp.119-144
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• 2021

Recently, as competition in the market evolves from the competition among companies to the competition among their supply chains, companies are struggling to enhance their supply chain management (hereinafter SCM). In particular, as blockchain technology with various technical advantages is combined with SCM, a lot of domestic manufacturing and distribution companies are considering the adoption of blockchain-oriented SCM (BOSCM) services today. Thus, it is an important academic topic to examine the factors affecting the use of blockchain-oriented SCM. However, most prior studies on blockchain and SCMs have designed their research models based on Technology Acceptance Model (TAM) or the Unified Theory of Acceptance and Use of Technology (UTAUT), which are suitable for explaining individual's acceptance of information technology rather than companies'. Under this background, this study presents a novel model of blockchain-oriented SCM acceptance model based on the Technology-Organization-Environment (TOE) framework to consider companies as the unit of analysis. In addition, Value-based Adoption Model (VAM) is applied to the research model in order to consider the benefits and the sacrifices caused by a new information system comprehensively. To validate the proposed research model, a survey of 126 companies were collected. Among them, by applying PLS-SEM (Partial Least Squares Structural Equation Modeling) with data of 122 companies, the research model was verified. As a result, 'business innovation', 'tracking and tracing', 'security enhancement' and 'cost' from technology viewpoint are found to significantly affect 'perceived value', which in turn affects 'intention to use blockchain-oriented SCM'. Also, 'organization readiness' is found to affect 'intention to use' with statistical significance. However, it is found that 'complexity' and 'regulation environment' have little impact on 'perceived value' and 'intention to use', respectively. It is expected that the findings of this study contribute to preparing practical and policy alternatives for facilitating blockchain-oriented SCM adoption in Korean firms.

• Korean Journal of Ecology and Environment
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• v.53 no.4
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• pp.365-373
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• 2020

Biomonitoring Survey and Assessment Manual for lake ecosystem suggest zooplankton collection methods to compare relatively the number of species, population density, and community indices, taking into account the convenience of the field sampling according to the sites' water depth. In this study, the oblique towing and 20 m vertical towing methods presented in the manual were respectively compared with the whole water column-vertical towing and we analyzed the differences and characteristics of zooplankton community information gathered by each collection method. For community indices, there was no difference in the comparison of oblique/vertical towing methods in the shallow lake, but in the deep lake, the diversity and richness indices increased when vertically towing through whole water column rather than when limiting the towing depth to 20 m. In addition, the total zooplankton density collected by the oblique/20 m vertical towing methods was about three times higher than the whole water column-vertical towing method, which means that the density of zooplankton community can be overestimated depending on the collection methods. It appears to be results of differences in the zooplankton density by water layer arising from their vertical distribution and in filtered raw water quantity according to the towing depth/distance. Hence, for zooplankton community information to be used as a functional quantitative indicator representing the entire lake, it would be more appropriate to apply the whole water column-vertical towing method with considering the distribution of zooplankton density by depth and contribution rate of each water layer when converting total zooplankton density.

• Korean Journal of Psychosomatic Medicine
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• v.29 no.1
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• pp.17-25
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• 2021

Objectives : This study aimed to investigate quality of life, severity of depression, suicidality, subjective health and subjective stress of depression with subjective cognitive decline in Korean adults. Methods : We used the 7th KNHANES data to enroll 415 participants with a score of 10 or higher on Patient Health Questionnaire-9 (PHQ-9), aged 20-64. Depression was divided into two groups based on the presence/absence of subjective cognitive decline. Demographic and psychological characteristics were compared between two groups. Correlation analysis of subjective cognitive decline, quality of life, depression, suicidal idea was carried out. To detect which variables influenced quality of life, a multiple regression analysis was carried out. Results : Among the 415 participants, 98 had depression with subjective cognitive decline. We identified significant differences in age, marital status, education, employment between the two groups. After adjusting for these variables, depression with subjective cognitive decline had lower EuroQol-5D index scores, more severe depressive symptoms without cognition and worse subjective health than depression without cognitive decline. There was a significant correlation between subjective cognitive decline and quality of life (r=-0.236, p<0.001), suicidal idea (r=0.182, p<0.001), depression score without cognition (r=0.108, p=0.028). Through multiple regression analysis, subjective cognitive decline was predictor of reduced quality of life (β=-0.178, p<0.001). Conclusions : Depression with subjective cognitive decline has poor quality of life and severe depression. Cognitive decline should be considered to improve treatment result in depression.