• Korean Journal of Environmental Biology
• /
• v.26 no.4
• /
• pp.385-391
• /
• 2008

In Korea, Quercus acutissima distributed in good condition with high nutrients and moisture content, but Quercus variabilis in dry soil or rock habitate. In order to understand this ecological distribution of Q. acutissima and Q. variabilis, we cultivated the seedlings of two oak species treated with light, soil moisture and nutrient gradients each four level, from May to October in glass house. Then we measured the ecological niche breadth and niche overlap of the two species, and analyzed the relationship of competition using cluster analysis and PCA ordination. Ecological niche breadths of Q. acutissima under moisture and nutrient treatments were slightly wider than those under light one. Among 14 characters measured, 6 characters related with length items were wider in all the environmental treatments, but 8 characters connected with weight terms narrower in light treatment. Ecological niche breadths of Q. variabilis under moisture and nutrient treatment were wider than those of light one. Ecological niche of Q. acutissima was wider than those of Q. variabilis in all the environmental treatments. Ecological overlap between two species was higher with a range of 0.87$\sim$0.92, especially higher in soil moisture factor. These results means that Q. acutissima is more competitive than Q. variabilis, especially in soil moisture condition. Two species were ordinated with distinct group based on 9 characters. From these results, it can be explained that what Q. variabilis distributed in bad soil condition is due to the escape strategy, because of its low competitive ability to Q. acutissima in natural communities.

• Journal of Internet Computing and Services
• /
• v.22 no.2
• /
• pp.89-107
• /
• 2021

This paper explores the empirically analyzes the competitive nature of the five social media by analyzing the proper SNS service such as Facebook, Instagram, YouTube, Pinterest, and Twitter. In this study, we surveyed the use and satisfaction of social media for SNS users by using the proper theory. A total of 224 users were selected for analysis. Based on the results of the questionnaire, factor analysis was carried out to extract common factors such as relationship, sociality, convenience, daily life, and entertainment. As a result of the research using proper analysis, Facebook showed the widest narrowness in sociality (.627) and convenience (.636) in the first place, and YouTube showed the lowest in daily life (.670) and entertainment (.615) In the relationship (.520), the Instagram was the widest. In terms of five factors, Facebook and YouTube have the greatest overlap in relationship (1.826) and sociality (2.696), while Pinterest and Twitter are the most common in daily life (1.937) and entertainment (2.263) There is redundancy, and for convenience (2.583), YouTube and Twitter have the most redundancy. Facebook, Instagram, and YouTube have a competitive advantage over Pinterest in terms of relationships, sociality, convenience, routine, and entertainment, and are competitive across all factors except Facebook, Instagram, and YouTube Twitter It is possible to confirm that it is superior.

• Korean Journal of Ecology and Environment
• /
• v.55 no.4
• /
• pp.360-367
• /
• 2022

Research on food sources through DNA metabarcoding is being used for various organisms based on high resolution and reproducibility. In the study, we investigated the difference in food sources between pre and post-starving in the three bivalve species (Anemina acaeformis, Anodonta woodiana, and Unio douglasiae) through DNA metabarcoding using 18S rRNA V9 primer. The food source of pre-starving appeared in 87 genera, 71 families, 51 orders, 35 classes, and 22 phyla. The primary food sources were the zoo and phytoplankton, including Chlamydomonadales, Euglenales, Ploima, Sphaeropleales, and Stephanodiscales. However, all zoo and phytoplankton were not observed after starving except Schizopyrenida and Rotifera. In Levin's niche breadth analysis, the Bi index of A. woodiana is 0.3, which was higher than A. acaeformis(0.14) and U. douglasiae (0.21), indicating that they feed on various food sources. The niche overlap of A. acaeformis was measured as 0.78 in A. woodiana, 0.7 in U. douglasiae showing a relative high value compared to other bivalves. The trophic level of A. acaeformis, A. woodiana, and U. douglasiae based on the food source information were investigated as 2.0, 2.0, and 2.5, respectively. The results of the previous study on the trophic level using stable isotopes showed 1.8 to 2.4 values were similar to the results of this study. These results suggest that DNA metabarcoding can be an effective analyzing tool for the gut content in the bivalves.

• Korean journal of applied entomology
• /
• v.53 no.4
• /
• pp.347-354
• /
• 2014

This study was carried out to clarify the change of butterfly community after clear cutting. Butterfly survey was conducted in clear cutting area, forest road, and forest using line transect method from May to November in 2011. A total of 32 species and 398 individuals of butterflies were observed. Abundance of food niche breadth and habitat type was significantly higher in clear cutting area than in forest. Estimated species richness and species diversity were significantly higher in clear cutting area than in forest. In clear cutting area, Leptidea amurensis and Argynnis niobe, vulnerable species, were abundant. This result suggests that grasslands formed by clear cutting play an important role to increase butterfly diversity in forest ecosystem.

• Korean Journal of Ecology and Environment
• /
• v.52 no.2
• /
• pp.126-135
• /
• 2019

We carried out a literature review of fish food sources research in the coast - estuary areas of Korean peninsula for the last fifty years(1969~2018). A total of 101 research papers were reviewed, of which 81 were published in domestic journals, 7 were puliched in domestic reports and 14 were published in international journals. When divided into the decade periods, 21 papers (19.4%) between 1990 and 1999 and 26 papers (24.1%) between 2000 and 2009, and 42 papers (48.1%) were published in 2010 and 2018, respectively. When divided into the survey area by a bearing (East sea, South-East sea, South Sea, and West Sea), 65 papers(69.1%) were carried out in the South Sea. Followed by 13 papers (13.8%) in the East Sea and 8 papers (8.5%) in the West Sea and the South-East Sea, respectively. The surveyed area was dominant in Gwangyang Bay (18 papers; 24.3%), followed by Gadeok-do (8 papers; 10.8%). Of the diversity indices, 14 indices were used to calculate the ecological status. The dominant indices were IRI(Index of relative importance), Pi(Prey-specific abundance) followed by E (electivity index) and Bi (dietary breadth index). A total of 11 statistical methods were used to find feeding strategy. The correlation analysis and Bray-Curtis similarity matrix were applied most frequently. In terms of ecological research topics, the papers focused on seasonal or spatial differences before 2000. Since 2000, specifically, the international journal papers have been published based on competition, sympatric, niche overlap and other ecological topics.

• The Journal of the Convergence on Culture Technology
• /
• v.9 no.2
• /
• pp.389-397
• /
• 2023

This study examines how macro-economic conditions, fashion momentum, and inter-genre competition affect movie genre's popularity, thus shaping fashion trends in the feature film market in Korea. Using panel data analysis of genre-specific audience sizes with 6 genre cateories and 132 monthly time points, we found that favorable economic conditions generate the fashion trend in the action/crime genre, while the deterioration of the economic conditions leads to the decline of action/crime genre. The finding implies that economic situations influence cultural consumers' psychological states, which in turn shape the fashion trend in certain direction. Furthermore, we found that the action/crime genre has a greater fashion momentum and its competitive power is stronger than other genres, suggesting that this genre has longer fashion cycle even if other genres rise to the top in their popularity. We argue that such enlengthened fahion cycle and competitive stength of the action/crime genre are associated with its breadth of niche width and audience loyalty. Scholarly and practical implications are discussed.