• Korean Journal of Ecology and Environment
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• 제53권4호
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• pp.445-452
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• 2020

In this study, we carried out a distribution and migration boundary lines of chum salmon (Oncorhynchus keta) in the Milyang River. We measured the total length of dead chum salmons. As a results, 40 chum salmons were found during the study period, 25 dead salmons and 15 alive individuals. The ratio of female was 64%. We verified the migration boundary lines of chum salmons based on a sighting survey until detecting a structure that chum salmons are not able to migrate upstream. We discovered that chum salmons were not able to migrate up to 13 km in a mainstream of the Milyang River and up to 12 km in the Danjang stream (a tributary of the Milayang River) from upstream of the Yerim Bridge. Therefore, our results indicate that Milyang River should improve a river connectivity by demolishing weirs that disturb chum salmon's migration or installing appropriate fishways. Also, effective legislations are needed to retain naturality in spawning ground and micro-habitats to increase the survival rate of parrs and smolts.

• Korean Journal of Ecology and Environment
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• 제54권2호
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• pp.108-119
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• 2021

We aimed to develop a naturalness index for forest-dwelling birds in four national parks in Korea and to simulate the effect of species loss on this naturalness index. Five bird specialists were asked to give 112 bird species a disturbance susceptibility score (DSS), and the naturalness index was calculated based on this. The 112 bird species represented 8 orders (Cuculiformes, Piciformes, Accipitriformes, Falconiformes, Columbiformes, Caprimulgiformes, Strigiformes, and Passeriformes). DSS was the highest for Terpsiphone atrocaudata and Pitta nympha, and lowest for Pica pica, Hypsipetes amaurotis, and Streptopelia orientalis. There was a significant negative relationship between a species' population number and its DSS. Among the four national parks, Mt. Songni had the highest naturalness index, followed by Mt. Wolak, Mt. Juwang, and Mt. Wolchul. We investigated the change in biodiversity indices under four scenarios, which assumed the extinction of species with less than 5 (Scenario 1), 10 (Scenario 2), 50 (Scenario 3), and 100 individuals (Scenario 4). The results showed that although all biodiversity indices decreased as the species loss increased, they all behaved differently. Fisher's alpha diversity decreased as the number of species proportionally decreased. There was almost no change in Shannon-Wiener H' index in Scenarios 1 and 2. The naturalness index showed increased sensitivity in Scenarios 1 and 4. Our future aims are to obtain the DSS for all forest-dwelling bird species, and to adopt the naturalness index to evaluate temporal and spatial changes in biodiversity.

• Korean Journal of Ecology and Environment
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• 제54권1호
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• pp.1-11
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• 2021

Fish community characteristics was investigated in Namyang Lake and tributaries in Han River basin, Korea from April to October 2015. During the period, there were 5,672 individuals of 20 species appeared from tributaries (St. 1~St. 6) and dominant species were Pseudorasbora parva (33.5%). Also 5,672 individuals of 20 species appeared in Namyang Lake (St. 7~St. 9) and dominant species were Carassius auratus (32.2%). There were 5 species of endemic species with Rhodeus uyekii, Acanthorhodeus gracilis, Squalidus japonicus coreanus, Abbottina springeri and Odontobutis interrupta from Namyang Lake watershed. The frequency of endemic species were higher tributaries (18.5%) than Namyang Lake (15%). Exotic species were 3 species with Carassius cuvieri, Lepomis macrochirus, and Micropterus salmoides. there were appeared more frequently Namyang Lake (15.0%) than tributaries(7.4%).

• Korean Journal of Ecology and Environment
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• 제53권4호
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• pp.311-323
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• 2020

We analyzed food sources of 45 fish species in 28 genera of 12 families based on literature data in freshwater ecosystems of South Korea. The food sources of 45 fish species included in a total of 26 phyla, 42 classes, 94 orders, 189 families and 294 genera. Among them, animal food sources were 16 phyla, 24 classes, 54 orders, 126 families and 212 genera, whereas plant food sources were relatively small with 10 phyla, 18 classes, 42 orders, 63 families and 82 genera. The animal food sources were classified into Arthropod, Insecta, Diptera and Chironomidae according to taxa. Meanwhile, Bacillariophyta, Bacillariophyceae, Cymbellales and Cymbellaceae were the most abundant among the plant sources. Self-Organized Map (SOM) and network analysis were conducted the food sources were classified into taxonomic groups and the feeding types of fish : 45 fish species were divided into five groups, characterizing 1) fishvores, 2) invertebratevores, planktivores including 3) zooplankton and 4) phytoplankton, and 5) omnivores. The network analysis presented link association between fishes and food sources. Macroinvertebrate including diptera and ephemeroptera were revealed as hub food sources based on network analysis. This literature study would expect that the application model with the food source of fish could be utilized for the evaluation of the food network or chain in freshwater ecosystems.

• Korean Journal of Ecology and Environment
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• 제53권4호
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• pp.324-330
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• 2020

Ozone (O₃) is a general disinfectant to remove micro-pollutants in water treatment system. Previous studies have reported effect of ozone to bacteria and pathogens removal, but its effect to the relatively large organisms has little known. In this study, we investigated potential effects of ozone toxicity to the non-bite midge larvae (Glyptotendipes tokunagai) with accumulate mortality, coloration change and expression of heat shock protein 70 (HSP70). The accumulate mortality rate of G. tokunagai increased in a dose-time dependent manner and the highest mortality rate was observed to 75% at 30 minute of exposure duration with 2.0 ppm of ozone concentration. Exposure to ozone was a factor increasing body color of the larvae. The tendency of HSP70 mRNA expression showed up-regulation in ozone exposure at 20 minute. After that time, the expression of HSP70 in exposed group decreased to a similar level of control group. Our results clearly showed that ozone toxicity affects physical and molecular activity of G. tokunagai, implying the potential hazardous of ozone in the aquatic ecosystem including macroinvertebrates.

• Korean Journal of Ecology and Environment
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• 제54권2호
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• pp.79-86
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• 2021

In this study, the distribution and habitat characteristics of Odontobutis obscura were investigated. It is a freshwater fish species which belongs to the Class I Endangered species as specified by the Ministry of Environment of South Korea. Sampling was conducted in the Sanyang Stream watershed between April and August of 2016. The Sanyang Stream watershed includes the Sanyang and Gucheon Streams, and their tributaries. Odontobutis obscura was caught at every sampling site, except sites 1~3, which are located in the lower part of the Sanyang Stream. Its habitat range extended from the headwaters to the lower parts of the stream that were not impacted by the South Sea. Salinity was the major factor limiting the distribution of O. obscura in the Sanyang Stream watershed. All individuals of O. obscura were caught in areas where the substrate composition was over 50% gravel. Furthermore, the substrate composition seems to be the most important habitat factor affecting spawning of O. obscura. Ecological studies of O. obscura are scarce, and this study is the first to report a detailed distribution for the species. Further studies on the physiology and ecology of O. obscura are essential for establishing preservation strategies for this endangered species.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• 제39권4호
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• pp.66-76
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• 2021

The purpose of this study was to analyze the transition process of Gyeongpo lake and to analyze the viewing characteristics of each period in the pavilion. The view characteristics at pavilion were analyzed by overlapping classification maps of landscape types by period with the view range map from pavilion. The circumference and area of Gyeongpo lake have been reduced to 15.2km and 3.9km² in the 1750s, 9.0km and 1.7km² in the 1933, and now 4.41km and 1.0km². By period, the largest decrease in the proportion of Gyeongpo lake viewed from Pavilion was Hwanseonjeong, which decreased by 48.0% from the 1750 to 2017. Hwallaejeong, Haeunjeong, and Hohaejeong were found to be impossible to view Gyeongpo lake as some of the adjacent lakes were changed to agricultural land. Pavilion has great significance as a space for traditional culture created in the background of humanities and natural environments. For the succession and development of Pavilion culture, it is necessary to use it as a cultural resource, to continuously manage the building, and to partially restore Gyeongpo lake considering the function of each pavilion.

• Journal of the Korea Convergence Society
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• 제13권4호
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• pp.45-51
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• 2022

Fear of contact exists due to the prevention of the spread of infectious diseases such as COVID-19. When using the common entrance door of an apartment, access is possible only if the resident enters a password or obtains the resident's permission. There is the inconvenience of having to manually enter the number and password for the common entrance door to enter. Also, contactless entry is required due to COVID-19. Due to the development of ICT, users can be easily identified through the development of face recognition and voice recognition technology. The proposed method detects a visitor's face through a CCTV or camera attached to the common entrance door, recognizes the face, and identifies it as a registered resident. Then, based on the registered information of the resident, it is possible to operate without contact by interworking with the elevator on the server. In particular, if face recognition fails with a hat or mask, the visitor is identified by voice or additional authentication of the visitor is performed based on the voice message. It is possible to block the spread of contagiousness without leaving any contactless function and fingerprint information when entering and exiting the front door of an apartment house, and without the inconvenience of access.

• Journal of Korea Water Resources Association
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• 제54권11호
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• pp.943-953
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• 2021

The propagation of impact wave induced by landslide and debris flow occurred on the slope of lake, reservoir and bays is a three-dimensional natural phenomenon associated with strong interaction of debris flow and water flow in complex geometrical environments. We carried out 3D numerical modeling of such impact wave in a bay using a multiphase turbulence flow model and a rheology model for non-Newtonian debris flow. Numerical results are compared with previous experimental result to evaluate the performance of present numerical approach. The results underscore that the reasonable predictions of both thickness and speed of debris flow head penetrating below the water surface are crucial to accurately reproduce the maximum peak height and free surface profiles of impact wave. Two predictions computed using different initial debris flow thicknesses become different from the instant when the peaks of impact waves fall due to the gravity. Numerical modeling using relatively thick initial debris flow thickness appears to well reproduce the water surface profile of impact wave propagating across the bay as well as wave run-up on the opposite slope. The results show that the maximum run-up height on the opposite slope is not sensitive to the initial thickness of debris flows of same total volume. Meanwhile, appropriate rheology model for debris flow consisting of inviscid particle only should be employed to more accurately reproduce the debris flow propagating along the channel bottom.

• Journal of Food Hygiene and Safety
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• 제36권6호
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• pp.537-545
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• 2021

This study investigated the characteristics of taste and flavor in various wintering-radish extracts using electronic sensors. Sourness showed the highest sensor value (6.9) in hot brewed extracts of white radish part. Saltiness showed the highest sensor value (8.0) in cold brewed extracts of green radish part. Umami showed the highest sensor value (8.3) in hot brewed extracts of white radish part. Sweetness showed the highest sensor value (6.8) in cold brewed extracts of green radish part. Bitterness showed the highest sensor value (7.5) in espresso extracts of green radish part. A total of 16 volatiles were identified using electronic nose. Among these volatile compounds in radish extracts, methanethiol was found to be the predominant volatile compound. These sensory characteristics in radish extracts can be used as basic research data in the food industry.