• Korean Journal of Breeding Science
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• v.42 no.1
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• pp.87-99
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• 2010

Genetic diversity and relationships within and among Korean, Japanese and Chinese Jilin provincial wild soybeans based on SSR markers were evaluated to enlarge genetic variation in soybean breeding in the future. A total of 184 wild soybeans including 67 Korean, 71 Japanese and 46 Chinese Jilin provincial wild soybeans were analyzed to evaluate genetic diversity and relationships based on 23 SSR markers. Korean and Japanese wild soybeans were obtained from National Agrobiodiversity Center, Korea, and Biological Resource Center in Lotus and Glycine, Frontier Science Research Center, University of Miyazaki, Japan, respectively. Chinese wild soybeans were collected from Jilin province, China. Twenty three SSR markers generated a total of 964 alleles with an average of 41.9 alleles per marker. Number of alleles ranged from 23 (Satt635) to 56 (Satt157). Genetic diversity (PIC value) of 184 wild soybeans ranged from 0.880 to 0.968 with an average of 0.945. Number of alleles for Korean, Japanese and Chinese Jilin provincial wild soybeans was 513 with an average of 22.3, 511 with an average of 22.2, and 312 with an average of 13.6 per marker, respectively. PIC value for Korean, Japanese and Chinese Jilin provincial wild soybeans was similar with an average of 0.905, 0.897, and 0.850, respectively. Cluster analysis based on genetic distances estimated by SSR markers classified wild soybeans into 3 clusters. Cluster I included only Chinese Jilin provincial wild soybeans. Cluster II included most of Japanese wild soybeans including 5 Korean wild soybeans. Cluster III included most of Korean wild soybeans including 6 Japanese and 1 Chinese Jilin provincial wild soybeans. Cluster I was not subclassified, but cluster II and III were subclassified into various groups. Genetic distance evaluated by SSR markers between Korean and Japanese wild soybeans was closer than that of between Korean and Chinese Jilin provincial, and between Japanese and Chinese Jilin provincial wild soybeans.

• Korean Journal of Breeding Science
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• v.42 no.2
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• pp.169-180
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• 2010

This study was conducted to investigate characteristics of panicle traits which are important factors affecting yield and grain quality of rice. Twelve panicle traits in 178 Korean rice varieties composed of 160 Japonica type varieties and 18 Tongil type varieties were investigated. Tongil type varieties had longer panicle and thicker neck node than Japonica type varieties. Other traits such as number of total spikelets, total rachis-branches, secondary rachis-branches (SRBs) per panicle, total spikelets on SRBs per panicle, mean number of spikelets on a SRB, and mean number of SRBs per primary rachis branch (PRB) in Tongil type varieties were also higher than in Japonica type varieties. On the other hand, Japonica type varieties were shown to have well exserted panicle and little more mean number of spikelets on a PRB than Tongil type varieties. According to cluster analysis based on 12 panicle traits, 178 varieties were divided into four main groups. Group I had 133 Japonica type varieties and was characterized by relatively well exserted short panicle, small thickness of neck node, few rachis-branches and little sink size than other group. Group II was composed of 24 Japonica type varieties and 6 Tongil type varieties showing medium value and range between Group I and III. Group III included 11 Tongil type varieties and 1 Japonica type variety 'Baegjinju1' characterized by relatively poor exserted long panicle, big thickness of neck node, many rachis-branches and large sink size. Group IV was solely composed of 'Nongan', which had well exserted long panicle, big thickness of neck node, many rachis-branches and large-sink size. In correlation analysis, number of total spikelets per panicle showed very high correlation with the number of total rachis-branches per panicle (r=0.975), number of spikelets on SRBs per panicle (0.962), number of SRBs per panicle (0.959), mean number of SRBs per PRB (0.746) and mean number of spikelets on SRBs (0.738).

• Korean Journal of Ecology and Environment
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• v.52 no.2
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• pp.71-80
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• 2019

Effects of environmental factors on phytoplankton succession and community structure were studied in Lake Chuncheon located in Bukhan River, South Korea. The data were sampled at three sites such as CC1 (lower side), CC2 (middle side), and CC3 (upper side of Lake Chuncheon) from 2014 to 2017. The annual average precipitation in Lake Chuncheon was 992 mm during the study period (2014~2017), and the annual precipitation was lower than 800 mm in 2014 and 2015. The annual average water temperature, total phosphorus (TP), and total nitrogen (TN) ranged from 17.0 to $21.1^{\circ}C$, 0.012 to $0.019mg\;L^{-1}$, and 1.272 to $1.922mg\;L^{-1}$, respectively. The TN concentration was relatively high in 2015 compared with the other study years, as a drought continued from 2014 to 2015. When comparing the correlation between precipitation and environmental factors, water temperature (p<0.01) and TP(p<0.05) showed positive correlations with rainfall. The average numbers of phytoplankton cells by branch were 2,094, 2,182, and $3,108cells\;mL^{-1}$ in CC1, CC2, and CC3, respectively. CC3 is considered advantageous for phytoplankton growth, even in small pollution sources due to low water depth. As a result of analyzing the relationship between precipitation and phytoplankton, the correlation between the two was shown to be high for 2016 (p<0.01) and 2017 (p<0.05), which is when precipitation was high. However, the correlation was not clear to 2014 and 2015. The relationship between water temperature and phytoplankton indicated a negative correlation with diatoms (p<0.01), yet positive correlations with green algae (p<0.01) and cyanobacteria (p<0.01). Diatoms increased in spring and autumn, which are characterized by low water temperature, and green algae and cyanobacteria increased in summer, when the water temperature is high. Our findings provide a scientific basis for characteristics of phytoplankton and water quality and management at the Lake Chuncheon.

• 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 Life Science
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• v.31 no.6
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• pp.543-549
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• 2021

Approximately 10% of all angiosperms belong to the Asteraceae family. Plant species belonging to this family have traditionally been used as medicinal plants in the Korean Peninsula. We investigated the antioxidant activity of seed extracts from 14 species belonging to the Asteraceae family. Seeds with ≥ 90% percentage of filled seed and ≥ 50% final germination were used. The total phenolic content was the highest in Dendranthema zawadskii var. tenuisectum (13.5 mg of gallic acid equivalents (GAEs)/g seeds), followed by Dendranthema zawadskii var. latilobum (11.8 mg of GAEs/g seeds), and Callistephus chinensis (11.0 mg of GAEs/g seeds). The total flavonoid content was highest in C. chinensis (9.8 mg of quercetin equivalents (QEs)/g seeds), followed by D. zawadskii var. tenuisectum (7.2 mg of QEs/g seeds) and Taraxacum officinale (6.3 mg of QEs/g seeds). Our results showed that 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity was highest in D. zawadskii var. tenuisectum (57.4 ㎍/ml), followed by T. officinale (59.1 ㎍/ml) and D. zawadskii var. latilobum (65.0 ㎍/ml), with a half maximal inhibitory concentration (IC₅₀) of DPPH scavenging activity. Furthermore, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity was highest in C. chinensis (26.2 ㎍/ml), followed by D. zawadskii var. tenuisectum (38.4 ㎍/ml), T. officinale (40.2 ㎍/ml), with a half maximal inhibitory concentration (IC₅₀) of ABTS scavenging activity. Based on a cluster analysis according to the antioxidant activity, the 14 species were classified into five groups, with group 4 having the highest antioxidant activity and group 0 having the lowest antioxidant activity. D. zawadskii var. latilobum, D. zawadskii var. tenuisectum, T. officinale, and C. chinensis belonging to groups 3 and 4, exhibited high phenolic content and antioxidant activity and can be considered potent plant-derived natural antioxidants.

• Journal of Science Education
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• v.45 no.3
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• pp.292-303
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• 2021

This study identifies the terms frequently used together with energy in online science news articles and topics of the news reports to find out how the term energy is used in everyday life and to draw implications for science curriculum and instruction about energy. A total of 2,171 online news articles in science category published by 11 major newspaper companies in Korea for one year from March 1, 2018 were selected by using energy as a search term. As a result of natural language processing, a total of 51,224 sentences consisting of 507,901 words were compiled for analysis. Using the R program, term frequency analysis, semantic network analysis, and structural topic modeling were performed. The results show that the terms with exceptionally high frequencies were technology, research, and development, which reflected the characteristics of news articles that report new findings. On the other hand, terms used more than once per two articles were industry-related terms (industry, product, system, production, market) and terms that were sufficiently expected as energy-related terms such as 'electricity' and 'environment.' Meanwhile, 'sun', 'heat', 'temperature', and 'power generation', which are frequently used in energy-related science classes, also appeared as terms belonging to the highest frequency. From a network analysis, two clusters were found including terms related to industry and technology and terms related to basic science and research. From the analysis of terms paired with energy, it was also found that terms related to the use of energy such as 'energy efficiency,' 'energy saving,' and 'energy consumption' were the most frequently used. Out of 16 topics found, four contexts of energy were drawn including 'high-tech industry,' 'industry,' 'basic science,' and 'environment and health.' The results suggest that the introduction of the concept of energy degradation as a starting point for energy classes can be effective. It also shows the need to introduce high-tech industries or the context of environment and health into energy learning.

• Journal of Nutrition and Health
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• v.56 no.2
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• pp.203-216
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• 2023

Purpose: This study examines the weight control behavior depending on university students' motives of using social media. Methods: The participants were 447 university students in the Jeonbuk area. Collected data were analyzed using factor analysis, cluster analysis, analysis of variance, and χ² tests with SPSS v. 26.0. Considering the motives of using social media, we investigated the usage of social media, dietary behavior related to social media, and weight control behavior. Results: Using the K-clustering method, the motives to use social media were categorized into three clusters: cluster 1 was the interest-centered group, cluster 2 was the multipurpose information-seeking group, and cluster 3 was the relationship-centered group. Among the various social media sites, YouTube (86.8%), Instagram (76.1%), and Facebook (61.1%) were the most visited by the subjects. The dietary behavior related to social media in cluster 2 was significantly higher than clusters 1 and 3 (p < 0.001). Clusters 1 and 2 showed a significantly higher dissatisfaction with one's weight (p < 0.05) and consequent interest in weight control than cluster 3 (p < 0.001). Cluster 2 used weight control-related information from social media significantly more than other clusters (p < 0.05). Weight control experiences in cluster 1 and 2 were significantly higher than in cluster 3 (p < 0.001). Conclusion: Differences in dietary behavior related to social media and weight control behavior were observed between cluster types of motivation to use social media. Based on the usage motives of university students and their behaviors, we propose that educational programs should be conducted for weight control using social media.

• Ecology and Resilient Infrastructure
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• v.10 no.3
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• pp.85-96
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• 2023

The study involved the categorization of domestic lakes located in South Korea into three groups based on their salinity levels: upstream reservoirs with salinity less than 0.3 psu, estuarine reservoirs with salinity ranging from 0.3 to 2 psu, and brackish lagoons with salinity exceeding 2 psu. Subsequently, the research assessed variations in the concentrations of total nitrogen (T-N) and total phosphorus (T-P) in the sediment of these lakes using statistical analysis, specifically one-way analysis of variance (ANOVA). Additionally, a laboratory core incubation test was conducted to investigate the benthic nutrient fluxes in Songji lagoon (salinity: 11.80 psu), Ganwol reservoir (salinity: 0.73 psu), and Janggun reservoir (salinity: 0.08 psu) under both aerobic and anoxic conditions. The findings revealed statistically significant differences in the concentrations of T-N and T-P among sediments in the lakes with varying salinity levels (p<0.05). Further post-hoc analysis confirmed significant distinctions in T-N between upstream reservoirs and estuarine reservoirs (p<0.001), as well as between upstream reservoirs and brackish lagoons (p<0.01). For T-P, a significant difference was observed between upstream reservoirs and brackish lagoons (p<0.01). Regarding benthic nutrient fluxes, Ganwol Lake exhibited the highest diffusive flux of NH₄⁺-N, primarily due to its physical characteristics and the inhibition of nitrification resulting from its relatively high salinity. The flux of NO₃^--N was lower at higher salinity levels under aerobic conditions but increased under anoxic conditions, attributed to the impact of salinity on nitrification and denitrification. Additionally, the flux of PO₄^3--P was highest in Songji Lake, followed by Ganwol Lake and Janggun Reservoir, indicating that salinity promotes the diffusive flux of phosphate through anion adsorption competition. It's important to consider the influence of salinity on microbial communities, growth rates, oxidation-reduction processes, and nutrient binding forms when studying benthic diffusive nutrient fluxes from lake sediments.

• Journal of Korea Water Resources Association
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• v.56 no.4
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• pp.285-299
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• 2023

Estimating the evapotranspiration is very important factor for effective water resources management, and FAO Penman-Monteith (FAO P-M) model has been applied for reference evapotranspiration estimation by many researchers. However, because various input data are required for the application of FAO P-M model, understanding the effect of each input data on FAO P-M model is necessary. Therefore, in this study, for 56 study stations located in South Korea, the effects of 8 meteorological factors (maximum and minimum temperature, wind speed, relative humidity, solar radiation, vapor pressure deficit, net radiation, ground heat flux), energy and aerodynamic terms of FAO P-M model, and elevation on FAO P-M reference evapotranspiration (RET) estimation were analyzed. The relative sensitivity analysis was performed to determine how 10% increment of each specific independent variable affects a reference evapotranspiration under given set of condition that other independent variables are unchanged. Furthermore, to select the 5 representative stations and perform the monthly relative sensitivity analysis for those stations, 56 study stations were classified into 5 clusters using cluster analysis. The study results showed that net radiation was turned out to be the most sensitive factor in 8 meteorological factors for 56 study stations. The next most sensitive factor was relative humidity, solar radiation, maximum temperature, vapor pressure deficit and wind speed, followed by minimum temperature in order. Ground heat flux was the least sensitive factor. In case of ground surface condition, elevation showed very low positive relative sensitivity. Relativity sensitivities of energy and aerodynamic terms of FAO P-M model were 0.707 for energy term and 0.293 for aerodynamic term respectively, indicating that energy term was more contributable than aerodynamic term for reference evapotranspiration. The monthly relative sensitivities of meteorological factors showed the seasonal effects, and also the relative sensitivity of elevation showed different pattern each other among study stations. Therefore, for the application of FAO P-M model, the seasonal and regional sensitivity differences of each input variable should be considered.

• Korean Journal of Culture and Social Issue
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• v.14 no.4
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• pp.19-37
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• 2008

The youth unemployment issue has not shown any improvement in years. The purpose of this study was to observe how employment issues affecting university students influence their life aims, self-efficacy, view of reality, view of the future, and life satisfaction. 239 students from three universities located in Seoul and Gyeonggi province were assessed through the instrument FLL and questions about employment issues, their life aims, life satisfaction and also their employment perspective. A total of 34 items of the FLL were divided through factor analysis into six higher life aims, self-love, family love and interpersonal aims, personal-financial aims, social-public aims, moral aims and political and ideological aims. Using Cluster analysis, three group profiles were found depending on the employment perspective such as a better view of reality, better self-efficacy, and better life satisfaction. A t-test was conducted in order to compare the two groups classified according to favorable or unfavorable employment perspectives. No significant differences existed between the groups in the perception of youth unemployment or in social-demographic factors, such as gender, age, and academic year. However, in life aims, the unfavorable group showed significantly higher interest in the domains of family love and interpersonal aims, personal -financial aims, and social-public aims than the favorable perspective group. Conversely, this group showed a significantly greater negative view of reality in most life domains, as it evaluated that its aims are more poorly achieved than the comparable group. Also, the unfavorable perspective group showed a lesser degree of self-efficacy in most life domains and the same in the category of life satisfaction, i.e., lesser satisfaction in all life domains except for family love, and moral aims. However, no significant difference existed between the groups in the view of the future. The results were discussed in relation to other social-cognitive factors for life satisfaction found in preceding studies.