• Current Research on Agriculture and Life Sciences
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• v.15
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• pp.69-81
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• 1997

For the prevention of worldwide prevalent disease of nuclear polyhedrosis virus (NPV), environmental conditions and their incidence of grasserie was investigated through 57 cases of silkworm rearing from the year of 1979 to 1993 in the countries of Korea, Japan, and Philippines. Relationship between the occurrence of NPV and environmental factors were also analysed from the aspect of causal pathogenesis. Unfavorable foactors related to the prevalence of NPV disease was reconfirmed by the assay of experimental rearing. Silkworms reared on mulberry leaves or artificial diet appeared similar result on the occurrence of grasserie. Disinfection by formalin and simple sweeping or washing was not significantly different on the occurrence of NPV disease. Following insufficient ventilation on the younger larvae. from the 1st to 3rd instar, the disease by NPV at the later stage was remarkably emphasized those insidence. An experimental rearing from 1993 to 1996 demonstrated the prevention of NPV disease by simple cleaning of sweeping under the condition of air forced ventilation, the customal practice of disinfection with formalin or any other chemical agents could be omissible.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.645-653
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• 2019

The purpose of this study was to understand the factors that affected activities and differences in seasonal activities of the invasive red-eared slider turtle (Trachemys scripta elegans) at Ansan reed wetland in Sangnok-gu, Ansan, Gyeonggi Province, the Republic of Korea. We installed nine nets in the study region to capture turtles and checked the nets twice a day for 154 days from April 28 to September 28 2013. In total, 60 individuals, including 12 juveniles, 26 adult males, and 22 adult females, were captured in 96 of 308 net checks. The multiple regression analysis of 12 environmental factors was conducted to analyze activity factors of red-eared slider turtle by assuming the number of turtles captured for a week to be the indicator of the activeness of the turtles. The result showed that the daylength was the only environmental factor that significantly affected the turtles' activity (p<0.001), and none of the other factors showed a significant correlation. The highest activity was recorded at the end of May, which was the beginning of the reproductive period. The daylength during the breeding season was significantly different from that during other seasons (Kruskal-Wallis test, p<0.001). The information about the relationship between environmental factors and species in habitat can be useful for the management of invasive alien species in the future.

• Korean Journal of Ecology and Environment
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• v.36 no.1 s.102
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• pp.74-82
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• 2003

This study was carried out to understand how the bird community would change in a stream ecosystem after implementation of close-to-nature river improvement techniques conducted on the Gwacheon, Seocho and Hakyeul reaches in the Yangiae Stream, 'Seoul. At the Gwacheon reach, the number of species and individuals tended to decline. However, at the Seocho reach, the number of species was increased while the number of individuals appeared to be not changed greatly. Especially, density of Dabbling Ducks were rapidly increased. At the Hakyeul reach was both the number of species and the number of individuals were increased. Density of Herons and Dabbling Ducks rose, while density of Wagtails was decreased suddenly. Except the Gwacheon reach, the survey areas were gradually improved in species richness and density after the construction of river improvement. We suggested that the naturally-formed meandering (channel) bar, restoration of riparian vegetation and artificial ponds were helpful for birds habitation, however bicycle path constructed in flood plain was negative.

• Korean Journal of Environment and Ecology
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• v.29 no.5
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• pp.753-763
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• 2015

To identify the overall status of vegetation in the nine ridges of the Jeongmaeks located in South Korea, the types of forest vegetation were analyzed with focus on the names of the plant communities that appeared in each Jeongmaek. The vegetation investigation data for the entire mountain ranges were used for quantitative analysis (TWINSPAN, DCA), thereby classifying the plant communities and understanding the structures and characteristics of the vegetation. Upon review of the ratios of the number of plant communities by each ridge of the Jeongmaeks, a relatively larger number of communities were found to be dominated by deciduous oak trees in the Honam and Nakdong Jeongmaek. In addition, the ratios of communities where deciduous oak trees and deciduous broad-leaved trees appeared were higher in the Hannam-geumbuk, Nakdong, Honam, Geumnam-honam, Geumnam and Geumbuk Jeongmaeks. On the other hand, Naknam, Hannam, and Hanbuk Jeongmaeks were shown to have the type of forest vegetation in which the ratio of artificial forests was high. According to the results of the quantitative analysis, eight communities were grouped as follows: Celtis sinensis-Mallotus japonicus, Deciduous oak, Pinus thunbergii-P. rigida, Quercus mongolica-P. densiflora, Q. mongolica-Q. variabilis, Q. mongolica-P. densiflora, Q. mongolica-broad-leaved deciduous and Q. mongolica-P. koraiensis communities. The typical forest vegetations in the Jeongmaeks were the Q. mongolica-dominant community, the P. densiflora-dominant community, and the deciduous oak-dominant community.

• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.193-204
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• 2004

This study was conducted to evaluate both temporal and spatial dynamics of phytoplankton community and environmental parameters in a newly made reclaimed esturine lake (L. Hwaong). Monthly sampling was conducted at 4 sites covering the longest transect of longitudinal gradient of the lake from June to November, 2002. Total 5 classes 8 orders 26 families 83 genus 192 species were identified at all study sites during the study period. Phytoplankton total cell density ranged 24${\sim}$ 1,882 cells $mL^{-1}$ and highly varied both temporally and spatially. Total cell density was significantly related with salinity, pH, BOD, COD, SS, TN and TP concentration. Diatom density also was significantly correlated with salinity, SS, BOD, COD and TN concentration, Although there was spatial difference, a longtudinal gradient appeared in phytoplankton cell density, Chl-a, TN and TP concentration from the mouth of river in June and August. In conclusion, phytoplakton community structure was dominated by diatoms (Bacillariophyceae), and appeared to be largely influenced by salinity, precipitation, and nutrients during the summer and the fall.

• Journal of The Korean Association For Science Education
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• v.19 no.1
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• pp.1-7
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• 1999

The purpose of this study was to survey the high school students' concern levels on decision-making problems based on biology, This study is a exploratory research to develop teaching strategies and curriculum of the common science for the enhancement of the students' decision-making ability in problems involved biological knowledges. The survey subjects were 101 first graders of the high school in Seoul area. The survey instrument developed was 5-point scale of Likert type consisted of 24 question items. The survey results showed that the concern level on selection of method for learning was the highest. The concern levels on selection of method for sports or diet which are the individual faced problems were high, and concern levels on the problems social issued such as decisions about standard for noise, pros and cons of approval for brain death or artificial abortion were high, too. The students' concern levels on problems individual context were significantly higher than concern levels on problems social context (p<0.01). The males' concern levels were higher than females' on 'AIDS', 'incinerator for rubbish', 'atomic power plant', 'protection policy for decreasing species', 'standard for noise' (p<0.05), And the males' concern levels were higher than females' on domain of 'ecosystem and environment pollution'. But the females had higher concern levels than males on 'diet' and 'surrogate mother' (p<0.05). The analyzed results were discussed in respects of implication for teaching strategies and curriculum.

• Korean Journal of Environment and Ecology
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• v.9 no.1
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• pp.15-29
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• 1995

To investigate plant community structure of Uiryung valley, Harujae valley, Kugi valley, Songchu valley, Tobongsan valley in Bukhansan National Park, each thirty eight, forty, twenty six. twenty eight, thirty six plots (plot size 100$m^2$) were set up and surveyed. The surveyed data were integrated and classification by TWINSPAN and DCA ordination techniques were applied to the study area. The plant community were divided into nine groups in seventy nine plots by TWINBPAN and the dividing groups were Carpinus laxiflora community(I), Quercus mongolica community(II), Pinus densiflora community(III), Q. mongolica-P. densiflora community(IV) Q. mongolica-Q. serrata- Prunus sargentii community(V), Q. mongolica Q. variabilis community(Ⅵ), Robinia pseudoacacia-Q. serrata community(Ⅶ). P. rigida-Q. serrata community(Ⅷ), Q. mongolica- Q. variabilis- Styrax obassia community(Ⅸ). So the successional trends of tree species at the natural forest seem to be from P. densiflora to Q. mongolica and at the artificial forest seem to be from R. pseudoacacia, P. rigida to Q. acutissima, Fraxinus rhynchophylla in canopy layer And in the subtree and shrub layer, it wag supposed that from Deotzia prunifolia, Rhus trichocarpa. Rhododendron yedoense var. poukhasleilse, Euonymus oxyphyllous to Magnolia sieboldii, Acer psuedo-sieboldianum, Lindera obtusiloba. In comparing successional trends with past study, it was postulated that successtion is not progressed by human disturbance and soil acidification by the air pollution.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1245-1255
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• 2022

Terra Nova Bay polynya (TNBP) is a representative coastal polynya in East Antarctica, which is formed by strong katabatic winds. As the TNBP is one of the major sea ice factory in East Antarctica and has a great impact on regional ocean circulation and surrounding marine ecosystem, it is very important to analyze its area change and development characteristics. In this study, we detected the TNBP from synthetic aperture radar (SAR) and optical images obtained from April 2007 to April 2022 by visually analyzing the stripes caused by the Langmuir circulation effect and the boundary between the polynya and surrounding sea ice. Then, we analyzed the area change and development characteristics of the TNBP. The TNBP occurred frequently but in a small size during the Antarctic winter (April-July) when strong katabatic winds blow, whereas it developed in a large size in March and November when sea ice thickness is thin. The 12-hour mean wind speed before the satellite observations showed a correlation coefficient of 0.577 with the TNBP area. This represents that wind has a significant effect on the formation of TNBP, and that other environmental factors might also affect its development process. The direction of TNBP expansion was predominantly determined by the wind direction and was partially influenced by the local ocean current. The results of this study suggest that the influences of environmental factors related to wind, sea ice, ocean, and atmosphere should be analyzed in combination to identify the development characteristics of TNBP.

• Journal of Korea Water Resources Association
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• v.56 no.3
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• pp.225-233
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• 2023

Urban rivers and their surrounding environments have been altered due to factors such as rapid economic growth and urban development. This alteration have caused the rivers to lose their original value and become exposed to various pollution, resulting decrease in citizens' quality of life. This study aims to estimate citizens' Willingness To Pay (WTP) for water quality improvement in Suyeong River in Busan. To estimate the non-market value of the Suyeong River, the WTP of Busan citizens for water quality improvement was estimated, applying Contingent Valuation Method (CVM). The WTP for improving the water quality from Grade 4(polluted water) to Grade 2(game fish like bass can live in it) was estimated using the water quality ladder concept of the US Environmental Protection Agency, assuming annual donations for five years. For the CVM, the logistic distribution and Spike Model were adopted. As a result, citizens residing in the surrounding area of Suyeong River expressed a higher WTP. Considering more than half of the Busan citizens are aware of the "conservation of nature and ecosystems" as a major function of the Suyeong River, this higher WTP could serve as a basis for improving the value of urban rivers.

• Journal of Korean Society of Forest Science
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• v.58 no.1
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• pp.41-47
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• 1982

The large devastated land in Young-il district, Gyeongsangbusdo, had been existed for a long time, and the Korean government had invested 3.8 billion won to control soil erosion of the area for 5 years from 1973 to 1977. This research was to investigate the changes of the soil profile and vegetation structure in the 3rd, 6th and 9th years since soil erosion control had implemented. The results obtained in this study are as follows: 1) The thickness of the litter layer (L), the fermentation layer(F), the humified layer(H) and the surface soil layer(S) increased with increasing years after implements soil erosion control project had started. 2) The H layer was not showed for the three years since the project had implemented but was in the sixty year. 3) The soil chemical elements including the organic matter and total nitrogen increased with increasing years after the project had started, the amounts of organic matter and total nitrogen were three and seven times higher respectively in the nineth year after project had started. The amounts of organic matter and total nitrogen were three and seven times higher, respectively in the nineth year after project started than those before. 4) Among the grasses and trees which had been sowed or planted during project period, the summed domination ratios for arundinella hirta var ciliare. Themeda japonica, Cymbopogen goeringi and Lespedeza bicolor decreased rapidly, while those for Robinia pesudoacacia and Pinus densiflora increased with increasing years after the project started. 5) The appearance of Quercus seedlings suited to this area and Pinus densiflora seedling which is a subclimax species increased with increasing years after the project started.