• Korean Journal of Environmental Biology
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• v.41 no.4
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• pp.335-344
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• 2023

Community composition and abundance of aquatic invertebrates are important for ecological functions. Community characteristics of insects and gastropods were compared in five regions to investigate the effect of geological factors in surveys conducted between June and August to analyze seasonal changes in invertebrate communities. Underwater traps were used to obtain a constant collection effect. Insect communities were dominated by Hydrochara affinis, Rhantus suturalis and Sigara nigroventralis, and nMDS analysis demonstrated the separation of their communities by region. H. affinis and Sternolophus rufipes were not found in Haenam and Cheolwon, respectively. The results showed the effects of regional temperature on the distribution of aquatic insects. Pomacea canaliculata, Hippeutis cantori and Austropeplea ollula were dominant in the gastropod community. The seasonal variation in the abundance of P. canaliculata was the most pronounced, and its abundance in August was 38.2 times higher than in June. The abundances of several species including Hippeutis cantori were negatively correlated with that of P. canaliculata. These results suggest that P. canaliculata is a pivotal factor that drives seasonal changes in gastropod community.

• Korean journal of applied entomology
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• v.38 no.2
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• pp.165-169
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• 1999

A study was performed on the susceptibility of Abate@ and Abate-S@ against 3rd instar larvae of 5 species of mosquitoes including Anopheles sinensis, Aedes dorsalis, Culex inatomii, Cx. pipiens pallens, Cx. tritaeniorhynchus and mosquito larvivorous fishes such as Chinese muddy loaches (Misgurnus muzolepis) and crucian carps (Carassius carassi~4s) in September, 1998. Cx. pipiens larvae showed that the LC5os of both Abatea and Abate-Sa were 0.006 ppm. The LC95 values of this mosquito species appeared 0.070 pprn of Abate@ and 0.035 pprn of Abate-S@ which were more susceptible than the dosage (1.0 ppm) recommended from WHO. An. sinensis larvae appeared 0.009 pprn of LC50 and 0.025 pprn of LCgs. The larvae of Cx. inatomii and Ae. dorsalis showed the most highly susceptible to Abate-S@ among the 5 mosquito species with LC50 values of 1.9 x pprn and 1.1 x pprn respectively, and the LC95 values were 5.2 x 10-hppm and 1.4 x ppm, respectively. On the other hand, Cx. tritaeniorhynchus appeared least affected by Abate-Sa. and was brought 0.048 pprn of LC50 and 0.808 pprn of LCg5. These two insecticides were much less toxic to the fishes than mosquito larvae showing the LC, value of Chinese muddy loaches at 24.145 pprn of Abate and 10.750ppm of Abate-S@. This fish species showed that the LCsos of Abate@ and Abate-S@ were 27.567 pprn and 14.775 ppm, respectively. In case of crucian carps, their LC, values were 7.914 pprn of Abate@ and 6.480 pprn of Abate-S@. Therefore, the maximum safe dosages of the insecticides to the fishes were 8 times as high as the values of LCg5 of the mosquito larvae. This study suggests that Abate@ and Abate-S@ demonstrated highly potential insecticides for further larger scale operational integrated control in some proper aquatic places if other aquatic invertebrates are also safe to the insecticides.

• Korean Journal of Environmental Biology
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• v.35 no.2
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• pp.169-174
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• 2017

Acute and chronic toxicities of methyl ethyl ketone and methanol were investigated on Paronychiurus kimi (Collembola), for evaluating the potential effects of accidental exposures of these chemical substances on the terrestrial environments. This study was undertaken to establish a toxicity database for these chemical substances, which was required for the preparation of the response compensation and liability act for agricultural production and environmental damage. The 7-d acute toxicity and 28-d chronic toxicity were conducted using the OECD artificial soil spiked with varying, serially diluted concentrations of methyl ethyl ketone and methanol. Mortality was recorded after 7-d and 28-d of exposures, and the number of juveniles were determined after 28-d of exposure in the chronic toxicity test. In both assessments, methanol was more toxic than methyl ethyl ketone in terms of mortality ($LC_{50}$) and reproduction ($EC_{50}$). The 7-d $LC_{50}$ of methyl ethyl ketone and methanol were 762 and $2378mg\;kg^{-1}$ soil dry wt., respectively, and the 28-d $LC_{50}s$ were 6063 and $1857mg\;kg^{-1}$ soil dry wt., respectively. The 28-d $EC_{50}$ of methyl ethyl ketone and methanol were 265 and $602mg\;kg^{-1}$ soil dry wt., respectively. Comparison of results obtained in this study with literature data revealed that P. kimi was more sensitive to methanol than other soil invertebrates. However, given the high volatility of the chemicals tested in this study, further studies are necessary to improve the current test guideline, or to develop new test guidelines for an accurate assessment of chemicals that require toxicity databases for chemical accidents.

• Applied Microscopy
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• v.40 no.1
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• pp.37-45
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• 2010

Captured wild specimens of the big white-toothed shrew, Crocidura lasiura were classified into three age classes by tooth wear and height of molars, and seasonal variations of breeding and reproductive organs were examined. Juveniles had not tooth wear in molars and height of the third molars were lower than the first and second molars, and had only non-breeding condition. Young adults had little tooth wear and the third molars reached to the first and second molars, and old adults had heavy tooth wear in molars, young adults and old adults had breeding or non-breeding condition according to the season. On the basis of histological examination, seasonal variations of breeding were confirmed that breeding condition of young and old adult males were continued from early February to early October although the breeding activity was the highest in April, that of females were continued from the end of March to October, males reached sexual maturity earlier than females. Whereas the breeding condition seems to cease for non-breeding season because of the deficiency of food resources, soil invertebrates. Young and old adult males of the breeding season had large testes with enlarged seminiferous tubules that were filled with numerous germ cells, and expanded caudal epididymides with a vast number of spermatozoa, and were more than 10.0 g in the body weight and 0.03 g in the testis and epididymis weight. The females of the breeding season were pregnant condition with 4~6 litters or had the Graafian follicles and the corpus lutea in the ovary, and were more than 9.6 g in the body weight.

• Journal of Life Science
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• v.26 no.11
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• pp.1259-1268
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• 2016

In this study, we investigated antimicrobial peptide from the acidified muscle extract of Mytilus coruscus, which mostly inhabits China, Japan, and Korea, to develop a natural product-derived antibiotics substitution in terms of its abuse and restriction. Antimicrobial peptide was purified by $C_{18}$ reversed-phase high-performance liquid chromatography and was detected as having a molecular mass of 6,701 Da by MALDI-TOF/MS. The N-terminal amino acid sequence of the purified peak was obtained from edman degradation, and 20 identified residues shown 100% identity with the N-terminus region of sperm-specific protein and protamine-like PL-II/PL-IV precursor of Mytilus californianus. We also identified 60 open-reading frame (ORF) encoding amino acids with 183 bp of purified peptide based on the obtained amino acid residues. The amino acid sequence of ORF showed 100% and the nucleotide sequence revealed 97.2% identity with the protamine-like PL-II/PL-IV precursor of Mytilus californianus. Synthesized antimicrobial peptide showed antimicrobial activity against gram-positive bacteria, including Bacillus cereus (minimal effective concentration [MEC], $20.8{\mu}g/ml$), Bacillus subtilis (MEC, $0.2{\mu}g/ml$), Streptococcus mutans (MEC, $0.2{\mu}g/ml$), gram-negative bacteria including Pseudomonas aeruginosa (MEC, $5.7{\mu}g/ml$), Escherichia coli (MEC, $2.6{\mu}g/ml$) and fungi, Candida albicans (MEC, $56.3{\mu}g/ml$). In addition, synthesized peptide showed stable activities under heat and salt conditions against gram-positive and gram-negative bacteria, but was inhibited by salt against only C. albicans. With these results, isolated peptide from M. coruscus could be an alternative agent to antibiotics for defending against pathogenic microorganisms, and helpful information to understand the innate immune system of marine invertebrates.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.257-267
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• 1993

Optimum pasture management during the summer season is an important factor to maintain good regrowth and persistence of pasture. The field experiment was carried out to investigate the effects of cutting management on growth and reserve carbohydrates in stubble. and on dry matter yield of orchardgrass dominated pasture during the mid-summer season. Three different cutting times(July 15, 25 and August 5) as a main plot and three cutting heights(3, 6 and 10cm) as a sub plot were disigned with three replications. The experiment was done at pasture of Changsung Agricultural High School in 1988. The results obtained were summarized as follows: 1. Temperature of soil surface and underground in the cutting of July 15 and July 25 was not showed significantly different, because of low intensity of radiation with a run of wet weather, and that of August 5 cutting tends to be lowed in high cutting height during the mid-summer season. 2. Amount of soil moisture against cutting height showed that high cutting had a low content. 3. Growth rate against regrowth of plant height, lear length and leaf area showed to be fast in high cutting. 4. Rapid recovery period of carbohydrate content after cutting and large amount of carbohydrate accumulation were showed in the cutting of July 15 and 25 compared with August 5 cutting in the reserve carbohydrate content against cutting of time and height during the mid-summer season. 5. Dry matter yield of the 4th and 5th cutting showed to be remarkable in July 15 cutting compared to those of July 25 and August 5. From the above results, it is suggested that the 10cm cutting height during the mid-summer season is the most effective for good regrowth, reserve carbohydrates and dry matter yield of orchardgrass.

• Korean Journal of Environmental Biology
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• v.28 no.4
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• pp.179-187
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• 2010

The Theory of Island Biogeography describes that the number of species on an island affected by island area and distance from the mainland. This study was performed to compare and analyze the community structure of the macro-invertebrates in three isolated islands, around Korean waters in terms of the Theory of Island Biogeography. Macrobenthic animals were collected using a modified underwater quadrat in August 2009. A total of 104 macrobenthic species were sampled with a mean density of 399 individuals $m^{-2}$ and biomass of 1,506.70 g $m^{-2}$. Based on the abundance and biomass data, there were 10 dominant species accounting for approximately 67.17% of total individuals. The highest densities were found in the amphipoda Amphipoda spp., the bivalvia Modiolus agripetus and Mytilus coruscus, the Sipunculida Phascolosoma scolops and the polychaeta Syllidae unid.. On the contrary, the top ten species made up 95.66% of the total biomass while the three most abundant, the bivalves M. coruscus, Streostria circumpicta and M. agripetus. The conventional multi-variate statistics (cluster analysis and non-metric multi-dimensional scaling) applied to assess spatial variation in macrobenthic assemblages. Cluster analysis and nMDS ordination analysis based on the Bray-Curtis similarity identified 2 station groups. The group 1 was consisted with Gageodo (except for lower station at Transect 2) and Dokdo station and was numerically dominated by the polychaetes Eunice antennata and Syllidae unid., the cirripedia Megabalanus rosa and the bivalvia M. coruscus. However, group 2 was associated with Sohwado station and was characterized by high abundance of the anomura Petrolisthes japonicus, the gastropoda Lirularia pygmaea and the brachiopoda Coptothyris grayi. In conclusion, these results suggested that the species diversity and community structure of macrobenthos in three isolated island seemed slightly related to island area and distance from the mainland.

• The Korean Journal of Pesticide Science
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• v.11 no.4
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• pp.246-253
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• 2007

The reproduction toxicity of several pesticides on two Korean water flea was investigated to develop a new standard species used for ecological risk assessment of pesticide. Moina macrocopa and Daphnia sp. were exposed to 4 different types of pesticides over 10 and 21 days, respectively. No-ohserved effect concentration (NOEC) for synthetic pyrethroid, fenpropathrin on Moina macrocopa and Daphnia sp. were 0.17 and $0.06\;{\mu}g\;L^{-1}$, respectively. Diazinon, carbofuran and myclobutanil were in the order of their reproduction toxicity to cladocerans tested. There were large differences between Moina macrocopa and Daphnia sp. in their susceptibility to fenpropathrin, diazinon and carbofuran except myclobutanil. Daphnia sp. is more sensitive than M. macrocopa to pesticides tested. Therefore Daphnia sp. may be a good surrogate species to assess the reproduction effect of pesticides on aquatic invertebrates. M. macrocopa also be a good surrogate species because it is one of the most abundant cladocera in agricultural environment, especially rice paddy in Korea. In addition to it's ecological importance of wide spread distribution, it has also economical importance to make possible to shorten period for reproduction test using M. macrocopa due to it's short life cycle.

• Korean Business Review
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• v.19 no.1
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• pp.53-80
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• 2006

This research has been accomplished to build up the growth strategies of Kangwon district's small & medium-sized construction firms. For this purpose, we made an investigation of the present situation and status for existing regional small & medium construction firms by analyzing data. Based on the results from this study, the following growth strategies are suggested to gain their competitive advantages. Firstly, most of all, the role of the top manager is the most important factor since most of the top manager for the small & medium-sized construction firms coincide with the owner the firms. Secondly, the specialization strategy is to establish. Above all they concentrate their business capacities on core business. Then, this growth strategy should be based on the selective escalation of functions in order to maintain an appropriate level of construction works. Thirdly, the specialized skills and skilled workers are ensured for competitive advantages. For human resource development, they should train workers to be multi-functioned on the assumption the they could stay at firm until they wish to retire. Finally, the government must also spare no effort to encourage the small & medium-sized construction firms to build up it's competitive power and cultivate it's spontaneous generation power though the reformation of system related whit the small and medium construction industry.

• Korean Journal of Environmental Agriculture
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• v.22 no.4
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• pp.246-250
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• 2003

In order to preserve the soundness of agro-ecosystem and products safety in agriculture, this study was evaluated environmental impact in relation to the INM (Integrated Nutrient Management) and IPM (Integrated Pest Management) at paddy fields at Ok-Chun and Yang-Pyung region. By introduction of INM with the application of BB(bulk-blanded) fertilizer based on soil analysis and IPM, the application rate of fertilizer was reduced to about $28.6{\sim}39.4%$ and the yield of brown rice was increased to about $3{\sim}10%$ compared to conventional practices. The concentrations of COD, $NH_4-N$, and $NO_3-N$ in irrigation water flowed to the environmental-friendly agriculture practices were 15.0, 0.67, and 1.39 mg/L, respectively. The concentrations of COD, $NH_4-N$, and $NO_3-N$ from paddy fields in drainage water were 12.4, 0.29, and 2.42 mg/L, respectively. The total number of the freshwater invertebrates was higher in field treated with fertilization by prescription with soil testing. Also, the population density of aquatic insects was higher than the other fields at both demonstration villages. In conclusion, it was possible to reduce the amount of fertilizer and agricultural chemicals application, and increase the yield of rice by application of the environmental-friendly agriculture practices.