• Journal of Marine Bioscience and Biotechnology
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• v.13 no.1
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• pp.58-65
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• 2021

In 2012, fishes caught by three-side fyke net in the coastal waters of Jedo were assessed for species composition and seasonal fluctuation in their abundance. The fish were caught at two research stations (St.) and were found to comprise 53 species, 39 families, and 9 orders. The dominant species were Takifugu niphobles, Lateolabrax maculatus, and Acanthopagrus schlegelii. To gain a measure of their biodiversity, all the species were assessed for their number, richness, diversity, evenness, and dominance. The highest and lowest number of total caught fish individuals was recorded in summer and winter, respectively. The diversity index was the highest in summer and lowest in winter. The evenness index was the highest in summer and lowest in spring. The richness index was highest in summer and lowest in winter. Furthermore, the dominance index was highest in spring and lowest in autumn.

• Korean journal of applied entomology
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• v.14 no.1 s.22
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• pp.21-22
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• 1975

• Korean Journal of Microbiology
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• v.34 no.3
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• pp.149-153
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• 1998

From soils seasonally collected at two depths (0~2 cm, $50{\pm}1cm$) of forest, field, grass land, or paddy field, distinct strains of actinomycetes were isolated and identified to the genus level. The genus-diversity of soil actinomycetes was revealed to be considerably different by seasonal change. It was also affected by soil depths, soil types, or actinomycete groups. At the soil depth of 0~2 cm, the seasonal distribution fluctuation (%) of streptomycete strains was higher in grass land (41%), field (39%) soil than paddy field (18%), or forest (18%), whereas that of streptomycete strains at the soil depth of $50{\pm}1cm$ was high in order of paddy field (36%), field (28%), grass land (26%), and forest (16%). On the other hand, the seasonal distribution fluctuation ratio of rare actinomycete strains at the soil depth of 0~2 cm was above 45% except for paddy field (26%). At the soil depth of $50{\pm}1cm$, the seasonal distribution of rare actinomycete strains exhibited high fluctuation (%) in order of forest (79%), paddy field (36%), field (24%), and grass land (10%).

• Korean Journal of Environmental Biology
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• v.37 no.3
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• pp.406-425
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• 2019

To observe the seasonal fluctuation of the meiobenthic fauna community around the coastal area of Jeju island, 20 stations were selected and seasonal surveys were conducted. Three-replicate meiobenthic samples were collected from each station in April, July, and November 2017; February, May, August, and November 2018; and February in 2019, in a total of eight months from 2017 to 2019. The total density of meiobenthos at each station ranged from 733 to 2,505 ind. 10 cm^-2. The month in which the highest habitat density appeared in most stations was April 2017 and the month in which the lowest habitat density was seen was February 2019. Nematodes were the most dominant faunal group among the representative 13 meiofaunal groups at all stations. The subdominant groups were benthic harpacticoid copepods and nauplius. The nematode/copepod (N/C) ratio, reflecting the health indices within the ecosystem, varied from 0.02 to 87.40 over the entire season and the average station values ranged from 2.00 to 16.80. The lowest N/C ratio value was found in April 2017 (0.02) and the highest N/C ratio was found at Station 11 in February 2019, which was 87.40, indicating the highest level of pollution. Seasonal and regional meiobenthos community structure similarity was divided into three groups through group analysis and multi-dimensional scaling (MDS) analysis, which showed that the meiobenthos community structure was affected by seasonal variations, rather than by regional differences.

• Korean journal of applied entomology
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• v.32 no.3
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• pp.348-353
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• 1993

The fluctuation of insecticide resistance in the green peach aphid (GPA) in fields was investigated by caboxy1 esterase (CE) activity index analysis. Of the GP A Populations occurred on the red pepper seedlings, aphids in the untreaLed and treaLed with acephate plots showed 40 and 78 resistance percent (RP), respectively. Aphids in the untreated kale field showed the RP value 24 in July, contrast to 83 in October. Mean RPs of aphids from 18 localities were 50 + 14 in summer and B2+ 10 in late fall, indicating a seasonal fluctuation of Lhe CE activity.

• Korean journal of applied entomology
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• v.32 no.4
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• pp.389-394
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• 1993

Seasonal fluctuation of Beet armyworm, Spodoptem exigua, adults and larvae were momtored by pheromone trap and direct obseration in the welsh onion field, respecLively. Adult peaked on mid~late November and occurred 4 Limes a year by pheromone trap at Yesan, 1990. There were 3 peaks a year at Asan, 1991. The highest number of adults were caught on early September. In Suwon, the yearly number of adults caught by pheromone trap was high in the order of 1990, 1991, and 1992. In 1992, the moLh was initily caught on mid April by pheromone trap at Koheung, Chonnam, and it vms 3 month earlier than that at Suwon. The larvae of beet armyworm at welsh onion field at Asan, 1991 was first found on late June and gradually increased until mid September. The density at peak occurrence was about 20 individual per 100 hills of welsh onion. The peak of the larvae appeared 20 days after peak emergence of adult. It is expected that there are 4 times of occurrence when the first egg of beet armyworm IS laid on mid May at Suwon. It takes 48, 25, 23, and 58 days to complete 1st, 2nd, 3rd. and 4th generation, respectively.

• Korean journal of applied entomology
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• v.32 no.2
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• pp.218-221
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• 1993

Sensitivities of insecticides and their seasonal variation were investigated against Myzus persicae. Some aphicides such as malathion were not effective on Myzus persicae in Chinese cabbage field. Difference of seasonal sensitivity was from I time to 16 times.

• Geomechanics and Engineering
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• v.18 no.6
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• pp.575-584
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• 2019

The groundwater level (GWL) is an important subsoil condition for the design of foundation. GWL tends to fluctuate often with seasonal variation, which may cause unexpected, additional settlements with some reductions in the safety margin of foundation. In this study, the effects of fluctuating GWL on the load carrying and settlement behavior of footing were investigated and quantified. A series of model load tests were conducted for various GWL and soil conditions using a hydraulically-controlled chamber system. Changes in load level and rising and falling GWL fluctuation cycle were considered in the tests. Settlements during GWL rise were greater than those during GWL fall. The depth of the GWL influence zone ($\underline{d}_{w,inf}$) varied in the range of 0.3 to 1.5 times footing width and became shallower as GWL continued to fluctuate. Design equations for estimating GWL-induced settlements for footings were proposed. The GWL fluctuation cycle, load level and soil density were considered in the proposed method. Changes in settlement and factor of safety with GWL fluctuation were discussed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.5
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• pp.510-520
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• 2010

This study investigated the community structure and seasonal variation of the fish assemblages on Jangbong tidal flat, Incheon, Korea. Fish were collected monthly using a small otter trawl from November 1999 to January 2001. Thirty-six fish species were recorded, with a mean density of 185 individuals and biomass of 2,594.3 gWWt. The most abundant species by number were Johnius grypotus (23.7%), Acanthogobius hasta (17.8%), and Cynoglossus joyneri (10.7%), while the dominant species by catch weight were Acanthogobius hasta (21.2%), Sebastes schlegeli (16.2%), J. grypotus (14.0%), and C. joyneri (10.8%). Cluster analysis and non-metric multi-dimensional scaling (nMDS) were applied to assess the seasonal fluctuation in the fish assemblages. Based on the result of the cluster analysis and nMDS ordination, the faunal group could be divided into cold- and warm-water specialist groups. The cold-water specialists included A. hasta, Acanthogobius luridus, Triaenopogon barbatus, Tridentiger trigonocephalus, and Liza haematocheila. The warm-water specialists were J. grypotus, C. joyneri, S. schlegeli, and Hexagrammos otakii. In conclusion, the community structure showed a distinct seasonal trend, which seemed to be related to the seasonal fluctuations in water temperature.

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.211.2-212
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• 2000

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