• The Journal of the Korea Contents Association
• /
• v.15 no.10
• /
• pp.116-126
• /
• 2015

The purpose of this study is to analyze the change of programming strategies of chinese broadcasting as competitions intensify in the niche dimension. Specifically, the niche breadth which indicates the diversity of program genre and way of program production, the niche overlap which indicates the degree of competition among the channels, are investigated. The results show, as the competition has intensified, three chinese television pursued different programming strategies; CCTV1 maintained programming strategy without big change, while Hunan and Gangso pursued change of programming strategy. However the change of programming strategies of Hunan and Gangso showed different direction; Hunan has tended narrows niche breadth of program genre and the way of progrm production, while Gangso broadens niche breadth. In overall, Chinese broadcastings have found the way of co-exist pursuing different programming strategy. And the programming strategy of Gangso satellite broadcasting which broadens niche breadth has showed better performance in rating and advertising revenue.

• Journal of Ecology and Environment
• /
• v.44 no.3
• /
• pp.162-177
• /
• 2020

Background: Ecologists have achieved much progress in the study of mechanisms that maintain species coexistence and diversity. In this paper, we reviewed a wide range of past research related to these topics, focusing on five theoretical bodies: (1) coexistence by niche differentiation, (2) coexistence without niche differentiation, (3) coexistence along environmental stress gradients, (4) coexistence under non-equilibrium versus equilibrium conditions, and (5) modern perspectives. Results: From the review, we identified that there are few models that can be generally and confidently applicable to different ecological systems. This problem arises mainly because most theories have not been substantiated by enough empirical research based on field data to test various coexistence hypotheses at different spatial scales. We also found that little is still known about the mechanisms of species coexistence under harsh environmental conditions. This is because most previous models treat disturbance as a key factor shaping community structure, but they do not explicitly deal with stressful systems with non-lethal conditions. We evaluated the mainstream ideas of niche differentiation and stochasticity for the coexistence of plant species across salt marsh creeks in southwestern Denmark. The results showed that diversity indices, such as Shannon-Wiener diversity, richness, and evenness, decreased with increasing surface elevation and increased with increasing niche overlap and niche breadth. The two niche parameters linearly decreased with increasing elevation. These findings imply a substantial influence of an equalizing mechanism that reduces differences in relative fitness among species in the highly stressful environments of the marsh. We propose that species evenness increases under very harsh conditions if the associated stress is not lethal. Finally, we present a conceptual model of patterns related to the level of environmental stress and niche characteristics along a microhabitat gradient (i.e., surface elevation). Conclusions: The ecology of stressful systems with non-lethal conditions will be increasingly important as ongoing global-scale climate change extends the period of chronic stresses that are not necessarily fatal to inhabiting plants. We recommend that more ecologists continue this line of research.

• Clinical and Experimental Reproductive Medicine
• /
• v.40 no.2
• /
• pp.47-54
• /
• 2013

To overcome the difficulty of controlling stem cell fate and function in applications to regenerative medicine, a number of alternative approaches have been made. Recent reports demonstrate that a non-cellular niche modulating the biophysical microenvironment with chemical factors can support stem cell self-renewal. In our previous studies, early establishment was executed to optimize biophysical factors and it was subsequently found that the microgeometry of the extracellular matrix made huge differences in stem cell behavior and phenotype. We review here a three-dimensional, non-cellular niche designed to support stem cell self-renewal. The characteristics of stem cells under the designed system are further discussed.

• Korean journal of communication and information
• /
• v.19
• /
• pp.7-36
• /
• 2002

The purpose of this study is to compare the webcasting and television from the perspective of genres. It adopted the niche theory in analyzing them, avoiding simply comparing the collective average of the two media's gratification. As a result, television turned out to expand broader at niche breadth than the Webcasting and thus presented more diverse functions thar the Webcasting. The niche overlap was investigated with the average of overlapping values. The competition between the two media was rather eased in dimensions of education, culture, and entertainment. And in terms of competitive superiority, the music service sector was the only function that the Webcasting had superiority to television. Upon the results, the Webcasting was absolutely inferior to television in a whole sense. But one thing which requires consideration is that the Webcasting will have functional mergers among genres and thus develop different functions from the corresponding ones of television.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.6
• /
• pp.805-811
• /
• 1995

Final biomass yields (peak optical density) and growth rates (divisions/day) of seven clones of Skeletonema costatum from Korean coastal waters were measured to understand their intraspecific variations in the light intensity niche component under $25^{\circ}C$ condition. Daily growth rates of 6 of 7 S. costatum, clones were maximum at 6000 lux while that of YS4, a neritic clone, was maximum at 9000 lux. The final biomass yields of 4 of the 7 S. costatum clones were maximum at the lowest light intensity of 2000 lux. Minimum final biomass yields were found at 9000 lux in all the S. costatum clones other than an estuarine clone, HDC9. The intraspecific variations of the mean growth rate and mean final biomass yield under each of the three different light intensity in terms of the coefficient of variation were not greater than 10% in any of the 7 S. costatum clones.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.5
• /
• pp.2121-2130
• /
• 2013

Based on the case study methods, the study analyzes that the countless UCC Cloud cloud is the niche creation by the lead users make process. This research show as follows. First, The Drama lovers and fan fiction writers are not only drama consumers but UCC creators/producers. By the process that the UCC and fan fiction is tailored to meet the needs of their users create fan fiction in fandom community, they create an entirely different niche from original drama. Second, the flow(drama consumption/evaluation, viewers needs/adaption, the user's creation/production) which community's creative users make sequentially coevolutes with the flow(drama information offer, intentionally supply/diffusion, derivatives production) of media companies. Third, the drama fandom community activities which is non-commercial activities form the drama ecosystem with a new paradigm, as well as form a virtuous cycle inked to the market continuously beyond fun, play, empathy.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.16 no.1
• /
• pp.159-170
• /
• 2013

The effect of climate change on urban woody plants remains difficult to predict in urban areas. Depending on its tolerances, a plant species may stay and survive or stay with slowly declining remnant populations under a changing climate. To predict those vulnerabilities on urban woody plants, this study suggests a basic bioclimatic envelop model of heat requirements, cold tolerance, chilling requirements and moisture requirements that are well documented as the 'climatic niche'. Each component of the 'climatic niche' is measured by the warmth index, the absolute minimum temperature, the number of chilling weeks and the water balance. Regarding the utility of the developed model, the selected urban plant's present probabilities are suggested in the future climate of Seoul. Both Korea and Japan's thermal thresholds are considered for a plant's optimal climatic niche. By considering the thermal thresholds of these two regions for the same species, the different responses observed will reflect the plant's 'hardening' process in a rising climate. The model illustrated that the subpolar plants Taxus cuspidata and Ulmus davidiana var. japonica are predicted to have low suitability in Seoul. The temperate plants Zelkova serrata and Pinus densiflora, which have a broad climatic niche, exhibited the highest present probability in the future. The subtropical plants Camellia japonica and Castanopsis cuspidata var. sieboldii may exhibit a modest growth pattern in the late 21C's future climatic period when an appropriate frost management scheme is offered. The model can be used to hypothesize how urban ecosystems could change over time. Moreover, the developed model can be used to establish selection guidelines for urban plants with high levels of climatic adaptability.

• Journal of Embryo Transfer
• /
• v.29 no.3
• /
• pp.221-228
• /
• 2014

Despite that porcine spermatogonial stem cells (pSSCs) have been regarded as a practical tool for preserving eternally genetic backgrounds derived from pigs with high performance in the economic traits or phenotypes of specific human diseases, there were no reports about precise definition of niche conditions promoting proliferation and maintenance of pSSCs. Accordingly, we tried to determine niche conditions supporting proliferation and maintenance of undifferentiated pSSCs for short-term. For these, undifferentiated pSSCs were progressively cultured in different composition of culture medium, seeding density of pSSCs, type of feeder cells and concentration of growth factors, and then total number of and alkaline phosphatase (AP) activity of pSSCs were investigated at post-6 day culture. As the results, the culture of $4{\times}10^5$ pSSCs on mitotically in activated $2{\times}10^5$ STO cells in the mouse embryonic stem cell culture medium (mESCCM) supplemented with 30 ng/ml glial cell line-derived neurotrophic factor (GDNF) was identified as the best niche condition supporting effectively the short-term maintenance of undifferentiated pSSCs. Moreover, the optimized short-term culture system will be a basis for developing long-term culture system of pSSCs in the following researches.

• Journal of Magnetics
• /
• v.21 no.4
• /
• pp.660-665
• /
• 2016

The electromagnetic apparatus plays an important role in high power electrical systems. It is of great importance to provide an effective approach for the optimization of the high power electromagnetic apparatus. However, premature convergence and few Pareto solution set of the optimization for electromagnetic apparatus always happen. This paper proposed a modified multi-objective particle swarm optimization algorithm based on the niche sorting strategy. Applying to the modified algorithm, this paper guarantee the better Pareto optimal front with an enhanced distribution. Aiming at shortcomings in the closing bounce and slow breaking velocity of electromagnetic apparatus, the multi-objective optimization model was established on the basis of the traditional optimization. Besides, by means of the improved multi-objective particle swarm optimization algorithm, this paper processed the model and obtained a series of optimized parameters (decision variables). Compared with other different classical algorithms, the modified algorithm has a satisfactory performance in the multi-objective optimization problems in the electromagnetic apparatus.

• The Korean Journal of Ecology
• /
• v.7 no.4
• /
• pp.208-232
• /
• 1984

A survey was conducted on the vegetation of Seogmo island, which is small island (ca. 41 okm2) located about 1km west of Kanghwa island in the central Korea, from Aug. 1983 to May 1984. Based on the field data, actual vegetation map and potential natural vegetation map were made. The island is covered with broad-leaved trees dominated with Quercus variabilis. The dominance diversity curves obtaiend in different associations are grouped in two types, lognormal distribution forms at the undisturbed vegetation and geometric series at the disturbed or rocky sites. It seems that the curves show to us the nature of their ecocline by the hypothesis of some investigators, i.e. Random niche boundary hypothesis, niche preemption hypothesis, lognormal distribution and logarithmic series. Total numbers of vascular plant species of the island were recorded 108 families, 348 genera, 475 species, 73 variaties and 7 forma. And Pte.-Q Index, 0.93, and Fisher's Index, 589.8, were higher than those in neighboring islands.