• Management Science and Financial Engineering
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• 제16권3호
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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.

• 한국환경생태학회지
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• 제22권6호
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• pp.609-615
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• 2008

본 연구는 경기도 백운산, 전남 지리산, 백운산, 조계산, 경남 금산 지역 등에 분포하고 있는 히어리개체군을 대상으로 2005년 8월부터 2006년 9월까지 20개의 방형구를 설치하여 자생지의 생태적 특성을 분석하였다. 식물사회학적 방법으로 분류한 결과 히어리개체군은 피나무우점개체군, 소나무우점개체군, 비목나무우점개체군으로 구분되었다. Ordination 분석 결과 피나무우점개체군은 해발고가 높으며, 전질소, 유효인산, CEC의 함량이 높은 입지에 분포하는 것으로 나타났다. 소나무우점개체군은 해발고가 낮고 전질소, CEC, 유효인산의 함량이 적은 입지에 분포하는 것으로 나타났다. 비목나무우점개체군은 해발고가 높고, 전질소, 유효인산, CEC의 함량이 중간인 입지에 분포하는 것으로 나타났다.

• 한국환경과학회지
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• 제32권12호
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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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• 제24권6호
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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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• 제32권3호
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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.

• 한국수산과학회지
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• 제47권6호
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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.

• 한국시뮬레이션학회논문지
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• 제2권1호
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• pp.67-77
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• 1993

• 한국어류학회지
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• 제12권3호
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• pp.186-191
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• 2000

충청북도 청원군 가덕면의 무심천 수역에 서식하는 Abbottina springeri를 대상으로 1995년 3월에서 11월에 걸쳐 생태학적 연구가 수행되었다. 물이 정체되고 하상이 뻘과 모래로 이루어진 곳에 주로 서식하였으며 전장 60 mm 이상의 개체는 유속이 완만한 여울에서도 상당수 채집되었다. 6월 개체군의 전장 분포를 보면 30~50 mm 군은 만 1년생, 50~65 mm군은 만 2년생, 65 mm 이상의 군은 만 3년생으로 추정되었다. 이차 성징은 추성, 혼인색, 생식공돌기에서 나타났으며 전장 55 mm 이상의 개체에서 5~6월에 가장 뚜렷하였다. 산란성기는 수온이 $20\sim25^{\circ}C$가 되는 6월이었으며 산란은 만 2년생부터 시작되었다. 암컷과 수컷의 성비는 1:0.93이 었으며 평균 포란수는 652개, 알의 직경은 $0.43{\pm}0.06mm$이였다. 소화관 내용물에는 조류가 가장 많은 비율을 차지하였으며 원생동물은 여름철에 많이 나타나고 전장 60 mm 이상의 큰 개체는 수서곤충도 섭식하고 있었다.

• ALGAE
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• 제27권1호
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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.

• 한국어류학회지
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• 제24권1호
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• pp.27-34
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• 2012

큰납지리 $Acheilognathus$ $macropterus$를 대상으로 2006년 3월~11월과 2008년 4월에 전남 영광군 불갑천 일대에서 생태적 특징을 밝히고자 조사하였다. 큰납지리는 물의 흐름이 느리고 바닥이 모래와 뻘로 이루어진 수역에서 대부분 서식하였다. 체장 48 mm 이하는 만 1년생, 48~58 mm는 만 2년생, 58~64 mm는 만 3년생, 66mm 이상은 만 4년생 이상으로 추정되었고 암컷과 수컷은 체장에 있어서 차이점을 보이지 않았다. 성비는 1 : 0.99 (female : male)이었고, 산란시기는 4~6월로 추정되었으며 이 시기의 수온은 $15{\sim}20^{\circ}C$이었다. 평균 포란수는 $680{\pm}209$개였으며 난경은 $1.92{\times}1.60mm$으로 나타났다. 소화관 내용물을 조사한 결과 규조류의 $Navicula$, $Cymbella$, $Fragilaria$와 같은 식물플랑크톤이 주로 관찰되었다.