• Management Science and Financial Engineering
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• v.16 no.3
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• pp.49-70
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• 2010

Customer population management models can be classified into three categories: the first category includes the models that analyze the customer population at cohort level; the second one deals with the customer population at aggregate level; the third one has interest in the interactions among the customer populations in the competitive market. Our study proposes a model that can analyze the dynamics of customer population in consumer-durables market at aggregate level. The dynamics of customer population includes the retention curves from the purchase or at a specific duration time, the duration time expectancy at a specific duration time, and customer population growth or decline including net replacement rate, intrinsic rate of increase, and the generation time of customer population. For this study, we adopt mathematical ecology models, redefine them, and restructure interdisciplinary models to analyze the dynamics of customer population at aggregate level. We use the data of previous research on dynamic customer population management at cohort level to compare its results with those of ours and to demonstrate the useful analytical effects which the precious research cannot provide for marketers.

• Korean Journal of Environment and Ecology
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• v.22 no.6
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• pp.609-615
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• 2008

The study was conducted to analyze vegetation and soil characteristic of Corylopsis coreana population in Baekunsan of Gyeonggi-Do, Jirisan, Baekunsan, Jogaesan of Jeollanam-do, and Geumsan of Gyeongsangnamdo. Field research was from September 2005 to September 2006. According to classification with phytosociological method, the Corylopsis coreana population was classified into Tilia amurensis dominant population, Lindera erythrocarpa dominant population, and Pinus densiflora dominant population. According to CCA ordination, the Tilia amurensis dominant population were located in area of high elevation, and high concentration in total nitrogen, available phosphorous, and cation exchangeable capacity(CEC). The Pinus densiflora dominant population were located in area of low elevation, and low concentration in total nitrogen, available phosphorous, and cation exchangeable capacity. The Lindera erythrocarpa dominant population were located in area of high elevation, and medium concentration in total nitrogen, available phosphorous, and cation exchangeable capacity.

• Journal of Environmental Science International
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• v.32 no.12
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• pp.943-953
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• 2023

This study analyzed the ecological characteristics of the wetland protection area at tthe Nakdong River through vegetation and biota surveys, which showed that brackish water meets fresh water, a unique ecological environment has been created, biodiversity is high, and diverse habitats are distributed. Eleven plant communities, including four woody communities and seven grass communities, are distributed along the coast, and a total of 514 species, including 11 endangered wildlife species, were identified in terms of species diversity. Among them, the species diversity of the Eulsuk-do area was found to be relatively higher than that of other Barreir Islands areas. The presence of a population of Sterna albifrons on Sinja-do and a population of Eremias argus on Jinwo-do, an area outside the boundaries of the wetland protection area, confirmed the conservation value of the wetlands and the need to expand the boundaries of the wetland protection area. It is judged that this information can be used as basic information for a systematic conservation and management plan for the wetland protection area at the Nakdong River Estuary and as basic data to support the establishment of a policy.

• The Korean Journal of Ecology
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• v.24 no.6
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• pp.341-348
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• 2001

Population dynamics of the oldest relic stand of Pinus densiflora for. erecta which remains as a status of patch in Sokwang-Ri area, Uljin-Gun, was studied to provide the basic data for conservation of the oldest pine stand in Korea. The upper slope site and ridge site including total 12 plots mainly represented Pinus densiflora for. erecta and Quercus mongolica. These two tree species showed reverse J-shaped distribution. From this information, it was concluded that intensive interspecific competition between two species could be occurring. Age distribution of P. densiflora for. erecta on the sites above middle slope area was indicated bi-modal type or tri-modal type which was known as an age structure of climax forest. Therefore, it was estimated that Pinus densiflora for. erecta population could be continuously maintained in the each patch above middle slope area. In the valley sites, hardwood species such as Q. mongolica, Q. variabilis, Styrax obassia and Acer pseudosieboldianum occupied most part of the under crown-cover area and their seedlings and saplings were developing into the closed upper layer crown because the height of upper layer crown reached about 35 meters and such a high crown height was more suitable for light utilization by plants of under layer. The growth patterns were mainly fluctuated for the entire life time of the oldest tree caused by frequent disturbance. And the initial growth curves of the mature trees and suppressed juvenile trees showed different tendencies along the sites.

• Journal of Ecology and Environment
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• v.32 no.3
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• pp.137-143
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• 2009

Pre-dispersal seed predation by a granivorous bird, the masked grosbeak (Eophona personata, Fringillidae), was investigated in two bird-dispersed trees, Celtis sinensis and Aphananthe aspera (Ulmaceae). The objectives of this study were to 1) measure direct damage of predation by grosbeaks on plant crops, 2) reveal the temporal pattern of predation within each tree species and its causal factors, and 3) test whether foraging grosbeaks hinder foraging of frugivorous birds, thereby indirectly impacting the reproduction of both tree species. A substantial amount of fruit and seed crop was consumed by grosbeaks (24.3% in Celtis; 55.5% in Aphananthe), and only 17.7% (Celtis) and 16.7% (Aphananthe) were removed by frugivorous birds. At the study site, the grosbeak population size fluctuated greatly during the fruiting seasons of both plant species. As for Celtis, predated seed density also fluctuated temporally, and the local population size of grosbeaks was responsible for predated seed density. In Aphananthe, predation was not fully explained by grosbeak populations or plant phenology, but its peak coincided with that of grosbeak population. These results suggest that predispersal seed predation by granivorous birds can have large negative impacts on the bird-dispersed plants. Changes in local population size of granivorous birds can influence predatation and can affect reproductive success of the bird-dispersed plants available to the birds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.901-907
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• 2014

We investigated the population ecology of blackthroat seaperch, Doederleinia berycoides, from samples collected in the southern seas of Korea from January to December, 2006. Population ecological parameters included survival rate, the instantaneous coefficient of natural and fishing mortality, and age at first capture. The survival rate (S) of blackthroat seaperch was estimated as 0.4966 using the catch curve method. The instantaneous coefficient of total mortality (Z) was 0.8598/year. The instantaneous coefficient of natural mortality (M) was estimated as 0.4694/year. From the estimates of Z and M, the instantaneous coefficient of fishing mortality (F) was calculated as 0.3904/year. The age at first capture ($t_c$), based on the Pauly method, was 2.87 years.

• Journal of the Korea Society for Simulation
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• v.2 no.1
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• pp.67-77
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• 1993

• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.186-191
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• 2000

Population ecology of Abbottina springeri has been investigated from March to November, 1995 at Musimchon stream of Kadok-myon, Chongwon-gun, Chungchongbug-do. The favorite habitat was a sluggish area with muddy bottom, but larger individuals more than 60 mm in total length were also collected at rapids of low velosity. Judging from the total length frequency in this population on June, total length 30~50 mm group is one year old, 50~65 mm group is two years old, and longer than 65 mm is regarded over three years old. Sexual dimorphism was revealed conspicuously in genital papilla, nuptial tuberles and nuptial pigmentation in the males at spawning season. Peak season of spawning was June when the water temperature reaches $20\sim25^{\circ}C$ and they start spawning at the age of two. The sex ratio of female to male was 1:0.93. The mean of egg number and egg size in ovary were 652 and 0.43~0.06 mm respectively. According to the contents of stomach, this species feeds mainly on botton algae at all ages and some aquatic insects in adult.

• ALGAE
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• v.27 no.1
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• pp.33-42
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• 2012

Population ecology of Palmaria palmata is described from the intertidal zone of Digby Neck and adjacent islands of Nova Scotia. The primary objectives were: to evaluate the difference in habitat specialization and population structure of P. palmata between harvest and non-harvest shores, and to characterize differences in thallus structure and frond sizes between epilithic and epiphytic populations. Harvest shores were gently sloping boulder fields with boulders typically about 0.5-1.0 m with dense cover of P. palmata on many of the rocks. Non-harvest shores (with or without P. palmata) consisted of boulders that were smaller or larger than harvest shores, or bedrock; when P. palmata was present on nonharvest sites it was typically epiphytic on other algae (e.g., Fucus spp., Mastocarpus stellatus, Devaleraea ramentacea). Harvestable epiphytic populations occurred only in high current areas. While there was little difference in average cover of P. palmata harvest and non-harvest shores ($31.2{\pm}13.7%$ vs. $19.4{\pm}7.3%$, mean ${\pm}$ standard deviation [SD]), the cover of P. palmata on harvest shores was highly skewed such that individual boulders often had >90% cover while adjacent rocks had little. Frond length of large fronds was greater on harvested shores, and mean frond density ($g\;m^{-2}$) was three times higher than the mean density on the non-harvested shores. Frond lengths of entire epiphytic and epilithic frond complements of 119 thalli from harvest beaches showed no difference in mean size of the largest fronds, and no difference in frond number per holdfast when epiphytic and epilithic thalli were compared.

• Korean Journal of Ichthyology
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• v.24 no.1
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• pp.27-34
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• 2012

Population ecology of $Acheilognathus$ $macropterus$ was investigated at the part of the Bulgapcheon stream in Korea from March to November in 2006 and April in 2008. It mainly inhabited in slow water with sand and mud bottoms. The standard length of this population indicated that below 48 mm group is one year old, 48~58mm group is two years old, 58~64mm group is three years old and longer than 66 mm group is regarded over four years old. The sex ratio of the female to the male was 1:0.99. Spawning season from April to June with the water temperature in $15{\sim}20^{\circ}C$. The average number of eggs in ovary was $680{\pm}209$. The matured egg size was $1.92{\times}1.60mm$. Stomach contents were mainly phytoplanktons such as the genera Navicular, Cymbella, Fragilaria.