• Sleep Medicine and Psychophysiology
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• v.23 no.2
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• pp.61-67
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• 2016

Objectives: We aimed to evaluate the effects of mattress type on both objective and subjective sleep quality in healthy good sleepers. Methods: Fifteen healthy good sleepers with a mean age of 30.8 years participated in this study. A randomized crossover trial was carried out using two different mattress types: a standard mattress and a contour coil mattress. After a night of adaptation, all participants were randomized to either a standard mattress or a contour coil mattress. Then, nocturnal polysomnography was conducted for two consecutive nights. Subjective evaluations were obtained using a self-report questionnaire before and after the polysomnographic recording sessions. Results: The polysomnographic showed no differences in total sleep time, sleep stage, or wake time after sleep onset between the two mattress conditions. Of the polysomnographic variables, only sleep onset latency was significantly reduced for the contour coil mattress. Additionally, participants reported better subjective sleep quality when sleeping on the contour coil mattress, according to the questionnaires. Conclusion: The type of mattress might affect not only subjective, but also objective sleep quality, including sleep onset latency.

• Korean Journal of Ecology and Environment
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• v.53 no.2
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• pp.173-184
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• 2020

Irrigation ponds, 'dumbeong', which are artificially constructed water resources for traditional farming, serve as a biological shelter connecting seasonally created rice paddy fields to local freshwater ecosystems. This 2018 study surveyed 143 irrigation ponds in the western Civilian Control Zone (CCZ) area from August to September, revealing species diversity and community characteristics of benthic macroinvertebrates. A total of 13,454 individuals of macroinvertebrates were captured and classified into 3 phyla, 5 classes, 17 orders, 59 families, 192 species. Among Insecta, the most frequently recorded order was Odonata, 55 spp.(33.7%), followed by Coleoptera, 52 spp. (31.9%), Hemiptera, 34 spp. (20.8%), Diptera, 17 spp. (9.8%), Ephemeroptera, 3 spp. (2.4%), Trichoptera, 1 spp. (0.6%) and Lepidoptera, 1 spp. (0.6%). Taxon of non-Insecta consisted of Mollusca, 14 spp. (48.2%), Annelida, 11 spp. (37.9%) and Arthropoda, 4 spp. (3.4%). The analysis of Diversity Index (H'), Species Richness Index (RI), Dominance Index (DI) and Evenness Index (J') revealed the general stability of communities in the study sites. A total of 28 rare species were found in 98 study sites, including three endangered species designated by the Ministry of Environment. These results showed that the species diversity and rarity of macroinvertebrates in the study area were greater than those of previous research on lentic wetlands (lake, etc.) and national conserved wetlands(Upo-swamp, etc.) in Korea. A conservation planning of aquatic ecosystems in the western CCZ area, therefore, should focus on conservation of irrigation ponds.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.230-243
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• 2000

A large-scale community data were patterned by utilizing an unsupervised learning algorithm in artificial neural networks. Data for benthic macroinvertebrates in streams of South Korea reported in publications for 12 years from 1984 to 1995 were provided as inputs for training with the Kohonen network. Taxa included for the training were 5 phylum, 10 class, 26 order, 108 family and 571 species in 27 streams. Abundant groups were Diptera, Ephemeroptera, Trichoptera, Plecoptera, Coleoptera, Odonata, Oligochaeta, and Physidae. A wide spectrum of community compositions was observed: a few tolerant taxa were collected at polluted sites while a high species richness was observed at relatively clean sites. The trained mapping by the Kohonen network effectively showed patterns of communities from different river systems, followed by patterns of communities from different environmental disturbances. The training by the proposed artificial neural network could be an alternative for organizing community data in a large-scale ecological survey.

• Korean Journal of Environment and Ecology
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• v.30 no.3
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• pp.353-368
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• 2016

This study surveyed the diversity and distributional characteristics of benthic macroinvertebrates and freshwater fish during the period from April to October, 2015 in Seonun Mountain Provincial Park. As a result, a total of 78 species of benthic macroinvertebrates belonging to 50 families, 16 orders, and four phyla were observed in Seonun stream; additionally, 25 species of freshwater fish belonging to six families were identified in all the investigated sites. Among benthic macroinvertebrates, Ephemeroptera(13 spp.: 22.81%) was the largest group in terms of species richness. In the FFGs, gathering-collectors(30 spp.: 36.14%) were relatively larger as represented by Ephemeroptera that usually inhabit fast flowing streams. In the HOGs, clingers(23 spp.: 29.49%) and burrowers(17 spp.: 21.79%) were the dominant groups. For both EPT ratio and ESB index, site 8 appeared to be the highest with 44.44% and 72 marks respectively, while the sites 4 and 9 showed relatively lower rates and indices. According to the results of evaluation, site 8 needs to be designated as the highest protection area while the sites 4 and 9 may be designated as target areas for preferential improvement. According to the analysis of fish community, the dominant species was Zacco teminchkii(333 inds.: 36.80%), and the dominant index was the lowest(0.24) and diversity index was the highest(1.81) at site 8, which therefore represents a stable freshwater fish community. In this survey, six Korean endemic species were identified: Ephemera separigata, Neoperla coreensis, Rhodeus uyekii, Squalidus gracilis majimae, Microphysogobio yaluensis, and Iksookimia koreensis. Also, three species belonging to the management of exportable group(Davidius lunatus, E. separigara, N. coreenis) were observed. Two habitat specific species: Thraulus grandis and Anguilla marmorata, were found for the first time in Gochang area and marked on the Korean distribution map through discussion.

• Korean Journal of Environment and Ecology
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• v.36 no.4
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• pp.368-380
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• 2022

Biomonitoring of an invasive alien crayfish species, Procambarus clarkii (Girard, 1852), was performed from February to October 2021, along with environmental DNA analysis, at five locations including Wanju-gun, Hampyeong-gun, Naju-si, Gurye-gun, and Cheongju-si. For the investigation, an umbrella-shaped trap for adults and a hand net for young crayfish were used, and 8 to 10L of freshwater was collected for eDNA analysis. The current status and past distributional records of crayfish in Korea were analyzed along with benthic macroinvertebrates at each survey site. As a result of the investigation, a total of 122 individuals were identified, and Hampyeong-gun recorded the largest number of populations with 59 individuals (48.36%) and the highest environmental DNA (eDNA). The frequency of appearance of P. clarkii was highest in May. The ratio of females to males was 21:5, and the body size was 72.2±21.1mm for female, 80.5±15.6mm for male, and 25.3±9.8mm for young crayfish. P. clarkii introduced into Korea is mainly spreading in the southwest region and it has not been observed in Seoul where there had been a record of appearance in the past. No external symbiosis (Branchiobdellida) of P. clarkii has been identified, and P. clarkii that has appeared in Korea was presumed to be imported from Japan. There are more than eight kinds of exotic crayfish distributed in Korea, and among them, the marbled crayfish (P. virginalis) was identified as a harmful species to the ecosystem of Korea by the Ministry of Environment in 2021. The identified species of benthic macroinvertebrates inhabiting the survey area where P. clarkii has appeared were 69 belonging to 39 families, 15 orders, five classes, and three phyla. Among them, Odonata were the most abundant (16 spp.; 24.62%), followed by Coleoptera (11 spp.; 16.92%) and Hemiptera (11 spp.; 16.92%). In the survey area, one Korean endemic species (Rhoenanthus coreanus), one species (Helophorus auriculatus) classified as Near Threatened (NT) on the Korean Red List, and six species of Crustaceans appeared. In the functional feeding group, the predators appeared predominantly while in habitat oriented group, the climbers appeared to be abundant. It was confirmed that P. clarkii in the survey area prefers an area rich in aquatic vegetation with waterside vegetation, and has high resistance to turbid water quality. The omnivore invader P. clarkii is expected to maintain a competitive relationship with carnivorous benthic macroinvertebrates that are predominant in the same species, and is expected to continue to generate ecosystem disturbance along the food chains.