• 환경생물
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• 제38권4호
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• pp.578-585
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• 2020

A new free-living marine nematode species of the genus Belbolla Andrássy, 1973 belonging to the family Enchelidiidae is described based on specimens collected from the sediment of a subtidal benthic environmental habitat in the East Sea, Korea. Belbolla wonkimi sp. nov. differs from its congeners by the combination of the following characteristics: a relatively long body (3263-3396 ㎛), the absence of ocelli, nine oesophageal bulbs in the posterior pharynx, well-developed two winged precloacal supplements, longer spicule length(115-130㎛, 1.6-1.8 anal body diameter long), and a triangle-shaped shorter gubernacular apophysis (17-18 ㎛). Comparative tables on the biogeographical and morphological characteristics of Belbolla species are presented. A DIC (differential interference contrast) photomicrograph of the new species is also provided. This is the first taxonomic report on the genus Belbolla from Korean waters.

• Journal of Species Research
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• 제12권1호
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• pp.55-67
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• 2023

Two new records of marine nematodes, belonging to the family Ironidae de Man, 1876, are reported based on the specimens collected from intertidal sediments from the west coast of Korea. Conilia sinensis is characterized by a relatively long body length, a well-developed buccal cavity with three claw-like teeth, the presence of a single spicule with transverse striations, the presence of rib-shaped telamons, and single precloacal supplement. Pheronous donghaiensis is distinguished from other species of the genus by a well-developed buccal cavity with four claw-like solid teeth and minute denticles, relatively short and thick spicules with the central septum, the presence of 8-9 curved tubular-shaped precloacal supplements, and a sharp pointed tail with three small tubular supplements arranged into two rows in males. In this report, we provide a taxonomic description and illustrations of two unrecorded species of the family Ironidae by differential interference contrast microscopy. This is the first taxonomic report on the species of the family Ironidae from Korea.

• Journal of applied mathematics & informatics
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• 제29권5_6호
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• pp.1193-1204
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• 2011

In the present paper we consider a differential-algebraic prey-predator model with stage structure for prey and harvesting of predator species. Stability and instability of the equilibrium points are discussed and it is observed that the model exhibits a singular induced bifurcation when the economic profit is zero. It indicates that the zero economic profit brings impulse, i.e. rapid expansion of the population and the system collapses. For the purpose of stabilizing the system around the positive equilibrium, a state feedback controller is designed. Finally, numerical simulations are given to show the consistency with theoretical analysis.

• ALGAE
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• 제35권1호
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• pp.61-78
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• 2020

Species belonging to the dinoflagellate genus Prorocentrum are known to cause red tides or harmful algal blooms. To understand the dynamics of a Prorocentrum sp., its growth and mortality due to predation need to be assessed. However, there are only a few Prorocentrum spp. for which heterotrophic protist predators have been reported. We explored feeding by the common heterotrophic dinoflagellates Gyrodinium dominans, Oxyrrhis marina, Pfiesteria piscicida, Oblea rotunda, and Polykrikos kofoidii and the naked ciliate Strombidinopsis sp. (approx. 90 ㎛ cell length) on the planktonic species Prorocentrum triestinum, P. cordatum, P. donghaiense, P. rhathymum, and P. micans as well as the benthic species P. lima and P. hoffmannianum. All heterotrophic protists tested were able to feed on the planktonic prey species. However, O. marina and O. rotunda did not feed on P. lima and P. hoffmannianum, while G. dominans, P. kofoidii, and Strombidinopsis sp. did. The growth and ingestion rates of G. dominans and P. kofoidii on one of the seven Prorocentrum spp. were significantly different from those on other prey species. G. dominans showed the top three highest growth rates when it fed on P. triestinum, P. cordatum, and P. donghaiense, however, P. kofoidii had negative growth rates when fed on these three prey species. In contrast, P. kofoidii had a positive growth rate only when fed on P. hoffmannianum. This differential feeding on Prorocentrum spp. between G. dominans and P. kofoidii may provide different ecological niches and reduce competition between these two common heterotrophic protist predators.

• 한국환경생태학회지
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• 제26권3호
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• pp.313-321
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• 2012

시흥시 토지이용유형별 야생조류 군집 특성을 분석하기 위하여 43개조사구를 선정하여 2009년 3월부터 2010년 2월까지 계절별로 군집구조 조사를 실시하였다. 조사는 정점조사법을 활용하였으며 군집분류는 TWINSPAN과 DCA기법을 활용하였다. 군집분류 결과 4개의 군집으로 분류되었으며 첫 번째 분류는 흰뺨검둥오리(Anas poecilorhyncha), 중대백로(Egretta alba)와 같은 물새류를 식별종으로 하여 나뉘어졌다. 분류된 2개 군집은 각각 논병아리(Tachybaptus ruficollis)와 참새(Passer montanus)를 식별종으로 다시 분류되어 총 4개의 군집으로 분류되었다. 분류된 군집은 토지 이용유형에 따라 나뉘어졌으며, 군집 I은 산림지역, 군집 II는 시가화지역과 반자연지역 일부(하천, 논습지)를 포함하였다. 군집 III은 하천과 논습지, 군집 IV는 저수지이었다. 하천과 논습지는 동일 토지이용유형이 서로 다른 군집으로 구분되었으나, 논습지와 주변 하천 규모에 따라 차이가 나타나고 있어 동일 토지이용유형의 면적 크기가 군집의 종 구성에 영향을 미침을 확인하였다. 종다양도지수는 군집 III(대규모 논습지와 주변 하천)이 가장 높았고, 군집 IV가 낮았다. 최대종다양도나 균등도도 군집 III이 높은 것으로 나타났다. 연구결과, 비오톱 유형화의 경우 도심 내 논습지 및 도시공원의 규모, 하천변의 토지이용형태를 고려할 경우 최소면적기준의 적용이 필요하였다.

• 한국잡초학회지
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• 제16권3호
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• pp.187-193
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• 1996

금강아지풀, 가을강아지풀, 강아지풀 종자의 발아특성과 제초제에 대한 반응차이를 조사하여 시험재료로서 발아력이 양호한 종자를 효율적으로 공급할 수 있는 조건들을 찾음은 물론 종간 발아특성 차이와 제초제에 대한 반응차이간의 관련성 여부를 검토하여 보았다. 금강아지풀의 경우 실온건조에서, 가을강아지풀 및 강아지풀의 경우는 저온습윤에서 가장 빨리 휴면타파 되었다. 휴면의 정도는 금강아지풀, 강아지풀, 가을강아지풀 순으로 강한 경향이었다. 금강아지풀의 경우 휴면타파된 종자를 저온습윤 또는 저온건조에 보관하더라도 발아력에 변함이 없었으나 가을강아지풀 및 강아지풀의 경우는 저온건조에 두면 발아속도가 늦어지며 초기발아율이 떨어지는 경향이었으나 50% 이상의 발아력(2개월째)은 유지하였다. 금강아지풀 종자를 실온건조에 보관할 경우 6년 이상이면 발아력이 감퇴되었다. 발아는 세 종류 모두 $30^{\circ}C$ 14시간/$20^{\circ}C$ 10시간의 온도조건에서 양호하였으며 광의 유무에 따른 발아율 타이는 인정되지 않았다. Cycloxydim, sethoxydim, primisulfuron 처리에서는 종간 반응차이가 없었으나, fenoxapropethyl은 가을강아지풀과 강아지풀에서, fluazifopbutyl은 가을강아지풀에서, clorimuron-ethyl은 금강아지풀파 가을강아지풀에서 감수성 정도가 약간 높았을 뿐이었다. 반면에 EK-2612는 반응 차이가 현저하여 강아지풀보다 금강아지풀에서 높은 감수성을 보였다. 이로 볼 때 동일 작용메카니즘을 가지는 약제들간에도 종간에 일관된 반응차이를 가지는 것이 아니라 오히려 화합물에 의존하는 반응을 보였으며, 종간 발아특성 차이와 제초반응과는 어떠한 관련성이 없었다.

• The Korean Journal of Ecology
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• 제16권3호
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• pp.287-303
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• 1993

A phytosociological study of forest vegetation of Mt. Kaya was carried out from August 1988 to September 1992. The forest vegetation of the area was classified into 3 communities (Quercus monogolica community, Lindera erythrocarpa community, Pinus densiflora community) and 3 subunits (Rhododendron mucronulatum subunit, Platycarya strobilacea subunit, typical subunit of Pinusdensiflora community). The Pinus densiflora community was located at the lower altitudes (100~300m) than those of other communities. The Lindera erythrocarpa community was located at the upper altitude (500m). Most of the inverstigated area were occupied by the secondary forest of Pinus densiflora community in the actual vegetation map and the profile diagram, suggesting that it was frequently destroyed by human interference

• Natural Product Sciences
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• 제10권6호
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• pp.325-329
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• 2004

The composition of essential oil from O. javanica was analyzed by gas chromatography-mass spectrometry. Using the broth dilution method and disk diffusion test, anti-microbial activities of the oil fraction and its main components were evaluated against various antibiotic-susceptible and resistant strains of pathogenic microorganisms. As a result of GC-MS analysis, 57 compounds, including ${\alpha}-terpinolene$ (28.1%), dl-limonene (16.0%), ${\gamma}-terpinene$ (10.3%), ${\beta}-pinene$ (9.7%) and ${\alpha}-pinene$ (6.0%) were identified in the essential oil fraction. The essential oil fraction of O. javanica and its main components exhibited significant inhibitory activities, particularly against Candida albicans (antibiotic-susceptible strains) and Streptococcus pneumoniae (antibiotic- susceptible and resistant strains). The main components of the O. javanica oil fraction displayed different patterns of activity against the three tested Candida species as exemplified by the differential minimum inhibiting concentration (MIC) values. The disk diffusion test showed that the activities were dose dependent.

• ALGAE
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• 제17권1호
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• pp.1-9
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• 2002

Diel vertical distribution of phytoflagellates and interactions between the phytoplankton components and environmental and biological factors were studied in a small artificial pond for three days on the December 18, 1998 and April 9 to 10, 1999. The phytoplankton population was dominated by Mallomonas akrokomos of chrysophytes and Cryptomonas marssonii and Chroomonas sp. of cryptophytes. The vertical distribution of these phytoflagellates taxa exhibited clear diel migration pattern. Moreover their migration patterns are showed differential fluctuation between M. akrokomos, C. marssonii and Chroomonas sp. The later two species upward migrated in the evening as well as night, whereas the former species migrated downward. Their distinctive migration pattern was found during the night but was not observed in the morning. During daytime C. marssonii and Chroomonas sp. showed maximum density above 2 m depth but M. akrokomos below 2 m depth. The diel vertical distribution of the dominant phytoflagellates did not show significant correlation between physical, chemical and biotic factors.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 춘계학술발표논문집
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• pp.842-844
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• 2009

The major group which contains all the organisms that are commonly termed Dinoflagellates is called the division Pyrrophyta or Dinophyta in botanical systems and the order Dinoflagellida or Dinoflagellata in zoological systems. Most dinoflagellates are biflagellated solitary planktonic cells. A taxonomic survey of the dinoflagellate family, Triadiniaceae Dodge was conducted for plankton monitoring network in the coastal waters of Korea. Identification of species in water samples was usually done by using differential interference contrast (DIC), which revealed especially well lighted thecal structures. For the apparent three-dimensional image, scanning electron microscope (SEM) was used. Two species were identified and described, which were Triadinium orientale(Lindemann)Dodge and Triadinium sphaericum(Murray and Whitting)Dodge.