• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.157-169
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• 2020

The purpose of this study is to investigate the ecological characteristics and vegetation structures of Eurya japonica in Busan. As a result of the TWINSPAN and DCA analysis, 89 plots of 100㎡ each were divided into 3 communities: Quercus serrata-Pinus densiflora-E. japonica community, Pinus thunbergii-E. japonica community, and P. thunbergii-Camellia japonica community. Community I consisted of the Quercus serrata-Pinus densiflora-E. japonica which was mainly located in the high altitude inland. While Q. serrata and P. densiflora competed in the tree layer, the dominant species of the understory layer was E. japonica. Since Carpinus tschonoskii, one of the climax species, was distributed evenly from shrub to tree layers, it was likely that deciduous oak trees or Carpinus tschonoskii would become dominant species in community I. In community I, E. japonica was found in higher altitude than the other evergreen broad-leaved tree and was expected to maintain their tree vigor even if the vegetation structure is converted into the deciduous forest. Community II, the P. thunbergii-E. japonica community, was predicted to maintain its tree vigor unless there were unexpected disturbance factors. Community III, consisting of P. thunbergii-C. japonica and located in Dongbaek Island, was under artificial management. In community III, P. thunbergii was the only species in the tree layer, while C. japonica was predominant in the understory layer. E. japonica and various evergreen broad-leaved tree species were present in the understory layer and shrub layer, which were unmanaged areas. Therefore, it is expected that unless C. japonica is continuously managed, E. japonica is likely to become the dominant species. There were also various evergreen broad-leaved species, such as Machilus thunbergii and Pittosporum tobira, present in the shrub layer. If the temperature continues to rise, the habitat is expected to become evergreen broad-leaved forests in the future as P. thunbergii community declines. The result of Pearson's correlation coefficient analysis of E. japonica and species appearing in 89 plots showed that 9 species were had a statistically significant relationship (p<0.05). Four species, including P. tobira and Q. dentata, had a positive correlation. Five species had a negative correlation, and C. japonica, which had the same ecological position as E. japonica, showed the most negative correlation at -0.384.

• International Commerce and Information Review
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• v.7 no.1
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• pp.121-144
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• 2005

This paper describes a theoretical model for investigating the relationship commitment of trade portal site 6C's. This research is the first to empirical test the causal relationships in Trade portal site. The relationship commitment for e-Trade portal site are tested here using data from 195 samples. Research methodology used in this study was mainly survey and questionnaire. Structural equation model is used in the hypotheses test. the results support all hypotheses involving hypothesis 1 and 6. The major finding of this paper would be summarized as followed: 1) Perceived relationship commitment of e-Trade site 6C's is positively related to contents, community, communication, customization in e-trade activity level and activity range of trade practical 2) Perceived commerce of electronic trade site is negatively related to the relationship commitment of trade companies. 3) Perceived e-trade site in electronic trade connection is positively related to the re-activity intention. In examining the relationships commitment of the factors, e-trade potal 6C's show in significantly by Contents, Community, Communication, Customization, Re-activity intention, but that show in not significantly by Commerce factor.

• The Journal of Korean Association of Computer Education
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• v.7 no.6
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• pp.117-128
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• 2004

Compared with traditional face-to-face instruction, online learning causes learners to experience more severe feeling of isolation and results in higher dropout rate. This is due to the lack of interaction, sense of belonging, membership, interdependency, cooperation among members and social environment that enables persistence in online learning. Therefore, it is very important for grouping e-learning community to lower the dropout rate and eliminate feeling of isolation. In this paper, the research has been done on the inclination test list to be applied for grouping the desirable learning community. And on the basis of this research, the grouping system for e-learning community(GSE) based on intelligent multi agents for an inclination test using homogeneous and heterogeneous items has been developed. GSE system has such properties that construct a personalized user profile by an agent, and then make groupings according to users' inclination. When this system was evaluated, about 88% of learners were satisfied, and they wanted the group not to be disorganized but to be maintained.

• The Journal of the Korea Contents Association
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• v.10 no.12
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• pp.274-289
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• 2010

MMORPG makes up 25.9% of domestic market share in game industry, and it has become increasingly fierce in competition. Game developer and publisher make every effort to build customer e-loyalty to sustain their competitiveness. Thus, this paper examines the determinants of e-loyalty that reflect the features of MMORPG such as intensive and real-time interactivity. For this purpose, we selected interactivity, sense of community, reward and fun as the key antecedents of e-loyalty based on the extensive review of previous researches related to online game and Internet service usage. A total of 202 responses were used for analysis and the research results are as follow. The findings show that interactivity, sense of community and reward influence significantly on fun, then fun is positively related to e-loyalty. Also, interactivity and reward are proven to have a positive influence on sense of community, and sense of community mediates the effect of interactivity and reward on fun.

• Journal of Korean Society of Forest Science
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• v.86 no.2
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• pp.223-232
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• 1997

One hundred Sixty two quadrats were sampled from natural forests, in Kangwon-do and Kyungsangbuk-do. On the basis of Mueller-Dombois & Ellenberg method, field survey, which accounts for the characters of the species structure of Pinus densiflora community and Quercus mongolica community, was carried out between 1991 and 1994. To analyze the data, CCA ordination and D.B.H, analysis were used. 1. DBH analysis showed that Pinus densiflora community is likely replacing Quercus mongolica or Quercus variabilis community. DBH analysis also showed that Quercus mongolica - Lindera obtusiloba community balances among the Quercus mongolica, Fraxinus rhynchophylla, and Tilia amurensid in the canopy, and that Quercus mongolica-Abies nephrolepis community, mixed forest balances among the Quercus mongolica, Pinus koraiensis, and Abies nephrolepis in the canopy. In general, Quercus mongolica seems to remain as a dominant species. 2. A certain correlation seems to exist between nutrients types and Pinus densiflora community. Quercus mongolica prefered to grow in the medium elevation area that has medium level of total nitrogen, organic matter, and C.E.C. Pinus densiflora, Quercus serrata and Quercus variabilis were found in the low elevation area that has low level of total nitrogen, organic matter, and C.E.C. 3. There seemed to be a certain correlation between nutrients types and Quercus mongolica community. Quercus mongolica and Acer pseudosieboldianum was distributed in the slope area that has medium level of $Mg^{{+}{+}}$, $Ca^{{+}{+}}$, and C.E.C., while Abies nephrolepis, Taxus cuspidata and Pinus koraiensis in the high elevation and ridge area that has low level of $Mg^{{+}{+}}$, $Ca^{{+}{+}}$, and C.E.C. Carpinus laxiflora and Abies holophylla were found in the medium elevation area that has medium level of $Mg^{{+}{+}}$, $Ca^{{+}{+}}$, and C.E.C., while Kalopanax pious, Carpinus cordata and Acer truncatum in the moderately moist and valley area that has high level of $Mg^{{+}{+}}$, $Ca^{{+}{+}}$, and C.E.C. Pinus densiflora and Fraxinus rhynchophylla seemed to prefer the slightly dry, low elevation and ridge area.

• The Korean Journal of Ecology
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• v.15 no.2
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• pp.103-115
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• 1992

This dissertation, which has been prepared in the region of cheju(33o31'N, 126o32'E) from may,1987 to appril, 1989, is to elucidate the dominant characteristics of early stages in secondary succession, by examining the life history of erigeron annuus for the seeding depth of a seed was dependent upon the degree of shading. That is, on the area of ocm,the more tense the shading was, the more germination percentage was increased, while, in the case of 1.5cm, it was somewhat increased, when shading bwcame ess and less tense. The rosette of e. annuus, through its relative light intensity was decreased by shading, up to 5% of natural light, showed some strong shade tolerance, which had no difficulty in matter production. The species diversity of mixed-species community was the highest in the middle of April, the lowest in the last of may. The dominance index was the highest in the late may, the lowest in the middle of April. Toward the end of may, the occupation rate of dominance species was the highest. There was a neutral relationship between intraspecific and interspecific, owing to the differentiation of its niche, temporally and spatially. Productive structure of the community revealed a narrow leaf type which was concentratively distributed in the mid part of community height. The relative light intensity of community ground surface was 6.1%, the leaf inclination 60o,the extinction coefficient(k) 0.4, biomass of community 1,045.6 g.d.w./m2,T/Rratio 9.3, C/Frate 7.0 and sumgermanition, shade toarance and community characteristics on erigeron annuus l.in chejumed leaf area index 3.88. through the various life cycles o e.annuus, we can say that it decreases mortality of seeding caused by some stress and disturbance, for germination lasts for a long time at any opportunity available, and it promotes population growth. The strong shade tolerance of a rosette and the variableness of a life from differentiate the niche between intraspecific and interspecific within the community, and avoid the direct competition between them, thus poromoting community growth.

• Proceedings of the Korea Contents Association Conference
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• 2006.05a
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• pp.39-42
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• 2006

I analyzed the results of the influences the community activities will have on students' participation and how much these influences will satisfy students in terms of learning in an e-learning-based environment. These results were based on former studies on this topic. I summarized the characteristics of community activities, the methods for motivating learning desire, and students' participation in the learning session. I found out that community activities can form intimacy, and that using cell phone text messages (SMS) and emails as learning methods can be a factor in students' participation.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.394-397
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• 2008

It is easy that students give up his study in e-learning environments. So it is critical for success of e-learning school to encourage students' aspiration to graduate study. This study examines the effect of sense of community to aspiration to graduate study and school loyalty in e-leaning school. I found that sense of community effect to school identification and that school identification effect to aspiration to graduate study and school loyalty.

• Journal of the Korean Operations Research and Management Science Society
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• v.35 no.1
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• pp.19-45
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• 2010

Virtual Communities, which are formed on the Internet, are expected to serve the needs of members for e-collaboration, e-communication, information and knowledge sharing. The executives of organizations should consider virtual community as a new innovation or knowledge pool since members share knowledge. However, many virtual community have failed due to members' low willingness to engage and furthermore to share knowledge with other members. Thus, there is a need to understand and foster the determinants of members' sense of belonging behavior in virtual community. This study develops an integrated model designed to investigate and explain the relationships between contextual factors, personal perceptions of virtual community, usability, trust and sense of belonging in using a certain virtual community. Empirical data was collected from 201 and tested using structural equation modeling (SEM) to verify the fit of the hypothetical model. The results show that the perceived usability and community trust of members significantly influences sense of belonging in using the virtual community, and information quality, system quality, familiarity on the virtual community are significantly influence the usability but not reputation. And I confirmed that perceived shared vision and responsiveness play the role of determinants in making the member's trust, perceived risk influence the making community trust in directly. The results of the study can be used to identify the motivation underlying members' sense of belonging in a certain virtual community by investigating the impacts of contextual factors and personal perceptions on virtual community, the integrated model better explains behavior than other proposed models. This study might help executives of virtual communities and organizations to manage and promote these determinants of sense of belonging to stimulate members' willingness to engage the community and futhermore enhance their virtual community loyalty.

• The Plant Pathology Journal
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• v.37 no.4
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• pp.396-403
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• 2021

Fire blight disease, caused by Erwinia amylovora, could damage rosaceous plants such as apples, pears, and raspberries. In this study, we designed to understand how E. amylovora affected other bacterial communities on apple rhizosphere; twig and fruit endosphere; and leaf, and fruit episphere. Limited studies on the understanding of the microbial community of apples and changes the community structure by occurrence of the fire blight disease were conducted. As result of these experiments, the infected trees had low species richness and operational taxonomic unit diversity when compared to healthy trees. Rhizospheric bacterial communities were stable regardless of infection. But the communities in endosphere and episphere were significanlty affected by E. amylovora infection. We also found that several metabolic pathways differ significantly between infected and healthy trees. In particular, we observed differences in sugar metabolites. The finding provides that sucrose metabolites are important for colonization of E. amylovora in host tissue. Our results provide fundamental information on the microbial community structures between E. amylovora infected and uninfected trees, which will contribute to developing novel control strategies for the fire blight disease.