• Journal of Korean Society on Water Environment
• /
• v.18 no.3
• /
• pp.261-270
• /
• 2002

The artificial aeration in the middle and the small scale reservoirs is widely used to destroy the stratified layer and algal boom. This study has been conducted at the Youncho reservoir located in Keoje island since Jan. 2000 to suggest the most suitable control strategy of the artificial aeration and reduce the side effect. The main results obtained from this research are as follows. The starting time of aeration for destratification was adjusted from the end of March to the beginning of April when the natural stratification is started. In order to prevent an anoxic condition the artificial mixing should be started by the middle of April when the DO in hypolimnion is dropped to less than $5mg/{\ell}$. The decrease DO, caused by the increase in water temperature, spreads rapidly from hypolimnion to themocline. Thermal stratification disappeared after the onset of artificial aeration within 7 days in the Yuncho reservoir. The air diffusers decrease water temperature in the layer of epilimnion and thermocline, but rise it in hypolimnion. The continuous operation of air diffuser prevent the stratification and anoxic condition in hypolimnion despite of the rising of water temperature and algal abundance. The algal abundance is not observed in effective zone by aeration. The turbidity rising problem induced from the aeration is avoided by keeping an air diffuser about 1.5m high from the bottom of lake. During the summer season, ceasing the aeration should be decided carefully. And also, it is necessary to operate the system it considering weather and temperature, and depending on the number and the position of aerators.

• Korean Journal of Remote Sensing
• /
• v.37 no.6_3
• /
• pp.1985-1999
• /
• 2021

The purpose of this study is to apply urban heat island reduction techniques(green roof, cool roof, and cool pavements using heat insulation paint or blocks) recommended by the Environmental Protection Agency (EPA) to our study area and determine their actual effects through a comparative analysis between land cover objects. To this end, the area of Mugye-ri, Jangyu-myeon, Gimhae, Gyeongsangnam-do was selected as a study area, and measurements were taken using a drone DJI Matrice 300 RTK, which was equipped with a thermal infrared sensor FLIR Vue Pro R and a visible spectrum sensor H20T 1/2.3" CMOS, 12 MP. A total of nine heat maps, land cover objects (711) as a control group, and heat island reduction technique-applied land covering objects (180) were extracted every 1 hour and 30 minutes from 7:15 am to 7:15 pm on July 27. After calculating the effect values for each of the 180 objects extracted, the effects of each technique were integrated. Through the analysis based on daytime hours, the effect of reducing heat islands was found to be 4.71℃ for cool roof; 3.40℃ for green roof; and 0.43℃ and -0.85℃ for cool pavements using heat insulation paint and blocks, respectively. Comparing the effect by time period, it was found that the heat island reduction effect of the techniques was highest at 13:00, which is near the culmination hour, on the imaging date. Between 13:00 and 14:30, the efficiency of temperature reduction changed, with -8.19℃ for cool roof, -5.56℃ for green roof, and -1.78℃ and -1.57℃ for cool pavements using heat insulation paint and blocks, respectively. This study was a case study that verified the effects of urban heat island reduction techniques through the use of high-resolution images taken with drones. In the future, it is considered that it will be possible to present case studies that directly utilize micro-satellites with high-precision spatial resolution.

• Research in Plant Disease
• /
• v.25 no.2
• /
• pp.79-83
• /
• 2019

To investigate the incidence status of lily viruses on Jeju island, lily samples were collected from 2015 to 2018 and examined for virus infection using RT-PCR. Of the viral infections, mixed and single infections were 70.0% and 17.9%, respectively. The incidence of mixed infections was highest for PlAMV and LSV as 43.4% in 2015; PlAMV, LSV 33.1% in 2016; LSV, LMoV 10.2% in 2017; and PlAMV, LSV, LMoV and CMV 15.8% in 2018. The incidence of PlAMV was observed to be 82.0% in 2015, 49.4% in 2016, 13.6% in 2017, and 39.5% in 2018 after the first occurrence of PlAMV in 2013. No symptoms were observed for single infection with LSV. However, in the case of mixed infection with LSV and LMoV, mosaic and leaf malformation symptoms appeared. With mixed infection with LSV and CMV, pale brown necrotic spots appeared, and mosaic and leaf curling were induced. PlAMV was more common in mixed infection than in single infection, and caused necrosis following the development of reddish-brown spots. PlAMV significantly decreased the marketability of lilies owing to the generation of leaf anomalies and curls, and its symptoms were more severe in mixed infections.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.38 no.4
• /
• pp.35-44
• /
• 2010

This study will define the features of the viewpoint that best enables the view of Busan Port from Young-Do. Special focus will be on spatial distribution, the type Busan Port sights that can be experienced from Young-Do, the compositional characteristic of a port landscape and visual characteristic. The results are based on 27 selected viewpoints and are as follows. Firstly, the patterns of the spatial distribution of viewpoints are classified as park, public facility and wayside types. It was found that most viewpoints are located along a wayside. Secondly, the types of Busan Port sights that can be experienced from Young-Do are divided into three kinds: surrounding stand-line type, facing the port and the type of penetrating city. The major type was of penetrating city among the three patterns. The reason for this is that the point of view for Busan Port was changed into a prospect over the sea since city and road sections have been expanding due to the urbanization of Young-Do. Thirdly, the compositional characteristics of the port landscape are divided into three styles: panoramic, corridor, and rooftop. The most frequent type is the rooftop style among the three characteristics. This fact indicates that the picture of Busan Port seen from Young-Do loses continuity of view and that housetops inhibit the sense of distance. Lastly, the visual characteristics of the viewpoint were analyzed. The angles of the declination of the viewpoints are concentrated on the horizontally closed parts. Thirteen points lie between $-3^{\circ}$ and $-1^{\circ}$, and twelve points between $-6^{\circ}$ and $-4^{\circ}$. The visual axes of the depression are two points because sight is interrupted by buildings which are built when the city expands. Two viewpoints for experiencing the optimum landscape of depression should be prepared to ensure continuous preservation of the viewpoints. The sight creates a wide prospect, reaching from 0.2km to 6.4km. It is expected that the results of this study can be used for the landscape plans of port cities including the management and preservation of viewpoints.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.48 no.5
• /
• pp.67-79
• /
• 2020

Plans to mitigate overheating in urban areas requires the identification of the characteristics of the thermal environment of the city. The key information is the distribution of higher and lower temperatures (referred to as "hotspot" or "coldspot", respectively) in the city. This study aims to identify the areas within Jeonju City that are suffering from increasing land surface temperatures (LST) and the factors linked to such this phenomenon. To identify the hot and cold spots, Local Moran's I and Getis-Ord Gi^* were calculated for the LST based on 2017 images taken using the thermal band of the Landsat 8 satellite. Hotspot analysis revealed that hotspot regions, (the areas with a high concentration of Land Surface Temperature) are located in the old town area and in industrial districts. To figure out the factors linked to the hotspots, a correlation analysis, and a regression analysis taking into account environmental covariates including Normalized Difference Vegetation Index (NDVI) and land cover. The values of NDVI showed that it had the strongest effect on the lowering LSTs. The results of this study are expected to provide directions for urban thermal environment designing and policy development to mitigate the urban heat island effect in the future.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.5 no.2
• /
• pp.3-18
• /
• 2002

This study has been carried out to find the water Quality in coastal sea of fungmun area, southern Jeju Island. In-situ observations and water sampling had been made every month from July 1997 to June 2000. The distributions of water temperature and salinity over the study area have been 13.8~27.0℃ and 30.0~34.7‰, respectively. Salinity is showed low salinity from June to September (rainy season) because of rain. Tsushima Warm Waters (TWW) as ≥15℃ and ≥34‰ influence the adjacent sea around Jeju Island all year round. Yangtse Coastal Waters (YCW) influence the surface layer around Jeju from June to September and so strong stratification (termocline, halocline) resulted at the depth of between 20~30m at outer-sea. However the stratification does not happen even in summer at inner-sea, which seem to be caused due to vertical mixing by wind, waves and tides. A water mass of high value of water temperature and salinity (respectively 14.1~17.7℃, 33.9~34.1‰) stayed at the lower layer in outer-sea all the year round. It is probably formed by mixing between TWW and YSBCW(Yellow Sea Bottom Cold Water). The mean value of DO was the lowest in summer and the highest in winter. COD and TH were the highest in summer and the lowest in winter. However, TP showed the lowest value in summer season, because the mean value of N/P ratio was over 16. The mean of N/P ratio was under 16 in other seasons. The phosphate would be a limiting factor in the growth of phytoplanHon in summer. Nitrate would be a limiting factor in other seasons. Distribution of chlorophyll a did not show any seasonal change in the study period, but especially increased during April and May in the first year(1998) and the second year(1999) all over the study area, which suggested that phytoplankton inhabitation distributed widely in the study area. The space averaged values were the highest for TIN in rainy season and lower for TP in rainy season than in other seasons. It suggests that river runoff influences the inner-sea.

• The Korean Journal of Malacology
• /
• v.31 no.1
• /
• pp.21-26
• /
• 2015

This study histologically describes the gonadal development and reproductive cycle of the abalone, Haliotis discus discus inhabiting Jeju Island of Korea. Gonads displayed histologically definitive seasonal changes. The gonad index (GI) of both females and males was the highest (3.2 and 3.3) in September and was the lowest (1.7 and 1.4) in January and February. Egg diameter increase from early stage in March and reach about $180{\mu}m$ to ripe stage in August. The condition index (CI) was highest in July and lowest in May. The pattern of changes in the GI, egg diameter and CI were similar to the pattern of seasonal changes in gonadal tissues. The female ratio (F/F + M) was 59% (n = 182:127). The reproductive cycle was divided into an inactive stage (January-February), early active stage (March-April), late active stage (May-July), ripe stage (August-October) and spent and degenerative stage (November-January). The main spawning period of H. discus discus was August to October at Jeju Island in 2014.

• Journal of Life Science
• /
• v.22 no.10
• /
• pp.1384-1391
• /
• 2012

Five coastal plant species, Artemisia fukudo, Aster sphathulifolius, Plantago camtschatica, Sedum oryzifolium, and Setaria viridis, were collected from the coastal region of Ulleung Island (Ulleung-Do, South Korea). Thirty-six endophytic fungi were isolated from the roots of these plants, and all were identified by using PCR with the following specifications: internal transcribed spacer 1 (ITS1), 5.8S rRNA, and ITS2 regions. Phylogenetic analysis indicated that all fungal strains belong to the phylum Ascomycota and comprise four orders (Capnodiales, Eurotiales, Hypocreales, and Pleosporales). Among all the identified species, the Eurotiales species were more abundant than species in the other orders. Nine different genera (Alternaria, Aspergillus, Cladosporium, Exserohilum, Fusarium, Neosartorya, Penicillium, Phoma, and Pyrenochaeta) in the four orders were confirmed. Penicillium and Aspergillus species were the most dominant species among the endophytic fungi isolated from the coastal plants. Shannon's diversity index (H') ranged from 0.684 to 1.609, and the endophytic fungi in S. oryzifolium was more diverse compared to the endophytic fungi in the other plants.

• Korean Journal of Plant Taxonomy
• /
• v.51 no.3
• /
• pp.205-249
• /
• 2021

This study was carried out to survey the flora of Hongdo Island in Sinan-gun, Jeollanam-do, South Korea. Specimens collected from previous Hongdo flora studies were reexamined using a relevant biodiversity database, and field surveys were carried out 22 times from April of 2003 to October of 2020. Based on the specimens collected during both previous studies and this study, the identified vascular plants of Hongdo consisted of 472 taxa comprising 102 families, 296 genera, 425 species, 6 subspecies, and 41 varieties. Among them, 111 taxa are newly recorded in this study, and 6 taxa are described in detail in terms of their morphological characteristics and habitat. Also, 29 taxa were reviewed or re-identified with corresponding taxonomic annotations. In Korea, Hongdo represents the northern distributional limit of the 4 taxa of Goodyera biflora, Damnacanthus major, Calanthe aristulifera, and Hemerocallis hongdoensis. Moreover, Hosta yingeri and Saussurea polylepis are endemic to Hongdo and nearby islands in Korea. Distribution maps of these species were prepared. Protected species designated by the Ministry of Environment were 7 taxa consisting of 2 taxa of level I, specifically Sedirea japonica and Neofinetia falcata, and 5 taxa of level II, which were Cymbidium macrorhizon, Woodwardia japonica, Dendrobium moniliforme, Calanthe aristulifera, and Bulbophyllum inconspicuum. Red list plants as designated by the National Institute of Biological Resources numbered 11 taxa. Naturalized plants numbered 40 taxa.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.26 no.5
• /
• pp.19-32
• /
• 2023

The fragmentation of habitats resulting from human activities leads to the isolation of wildlife and it also causes wildlife-vehicle collisions (i.e. Road-kill). In that sense, it is important to predict potential habitats of specific wildlife that causes wildlife-vehicle collisions by considering geographic, environmental and transportation variables. Road-kill, especially by large mammals, threatens human safety as well as financial losses. Therefore, we conducted this study on roe deer (Capreolus pygargus tianschanicus), a large mammal that causes frequently Road-kill in Jeju Island. So, to predict potential wildlife habitats by considering geographic, environmental, and transportation variables for a specific species this study was conducted to identify high-priority restoration sites with both characteristics of potential habitats and road-kill hotspot. we identified high-priority restoration sites that is likely to be potential habitats, and also identified the known location of a Road-kill records. For this purpose, first, we defined the environmental variables and collect the occurrence records of roe deer. After that, the potential habitat map was generated by using Random Forest model. Second, to analyze roadkill hotspots, a kernel density estimation was used to generate a hotspot map. Third, to define high-priority restoration sites, each map was normalized and overlaid. As a result, three northern regions roads and two southern regions roads of Jeju Island were defined as high-priority restoration sites. Regarding Random Forest modeling, in the case of environmental variables, The importace was found to be a lot in the order of distance from the Oreum, elevation, distance from forest edge(outside) and distance from waterbody. The AUC(Area under the curve) value, which means discrimination capacity, was found to be 0.973 and support the statistical accuracy of prediction result. As a result of predicting the habitat of C. pygargus, it was found to be mainly distributed in forests, agricultural lands, and grasslands, indicating that it supported the results of previous studies.