• Journal of Fisheries and Marine Sciences Education
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• v.11 no.2
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• pp.203-215
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• 1999

Floating debris was recorded from a training ship, Kaya, of Pukyong National University with about 12 knots speed at July 19~21, 1999 and July 24~26. The sampled area is the Yellow Sea (YS) connected from Cheju Is. of Korea to Qindao harbor of China, divided into 88 unit segments on survey routes. Debris fabrication materials were categorized with 6 items using the following; man-made or natural wood items, paper and cardboard, nylon netting and rope, styrofoams, vinyl and plastics, floating metal and glass containers. All identified items within a $120{\pm}20m$ wide band were recorded but ignored if beyond this boundary. The results of distribution of floating debris in the area are as follows: 1. The greatest quantities of marine debris discovered during the survey were $184pieces\;per\;km^2$ near Qindao harbor. The next polluted areas, Sohuksan islands, positioned in the eastern part of YS were scattered in about $40pieces/km^2$ or so. 2. Among items, woods, paper and cardboard, vinyl and plastics were found out near Qindao Coast of China. On the other hand, there were many styrofoams, nylon netting and rope near the area of Sohuksan islands in the eastern part of YS. 3. The distribution densities of western part of YS near Qindao are varied with largely range in items and quantities but those of the eastern part, near Sohuksan islands were nearly constant. 4. Styrofoams were composed of 63% among all debris in YS, next paper and cardboard 15%, and wood item, vinyl and plastics each 10%. Therefore, marine debris of YS is revealed that distribution characteristics and composition are very different in each area. These phenomena are concluded that they largely depend on the life styles in land and the utilities of the sea. And of items, styrofoams is dominated by the distribution pattern of YS. Furthermore, surveys are continuously being investigated, and from this it is hoped that a much wider coverage can be achieved, perhaps all sites of the YS and contributed to the finding sources, the stationary area and removal method of debris joined the flow patterns.

• Korean Journal of Ecology and Environment
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• v.43 no.2
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• pp.263-270
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• 2010

This is a research on development of water purification equipment called artificial floating island (=AFI) for the stagnant water area which can secure exuberant landscape and water-friendility. The equipment devised in this study is designed to make up the weakness of conventional AFIs and improves the removal efficiency of pollutants using the mixture of media and plants. The air compressor positioned at the inlet releases air with inflow continuously, the water pump at the outlet sprays as a form of fountain with causing a disturbance on stable water column, then, both of them contribute improvement of water quality over a large area. We applied Bio-stone as a media in this system and performed an experiment of pre-efficiency test, and we concluded that the higher pollutants concentration of inflow, the higher removal efficiency we obtained. At the result of lab-scale experiment, in the case of high-concentration inflow, in the removal efficiency of SS is 62.2%, BOD is 50.2%, COD is 55.1%, T-N is 31.6%, T-P is 38.4%. In addition, to evaluate the field application, we set up the facilities in Sin-gal lake located in Yongin-Si Gyeonggi-Do, and researched on the removal efficiency of outflow relative to the inflow. As a result, SS is 53.5%, BOD is 32.8%, COD is 36.9%, T-N is 22.6%, T-N is 33.2%.

• Journal of Navigation and Port Research
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• v.29 no.6 s.102
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• pp.537-545
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• 2005

Traditionally Jeju island has a mild oceanic climate throughout the year and famous as worldwide resort area bemuse of its pure natural environment and dramatic coastal scenery. But unpredicted coastal erosion problem, mused by variation of environmental conditions from construction of coastal structure and renovation of the existing ports, has raised its head above the water, and is becoming serious these days just like other coastal area in Korea. The phenomena happen here along the seaside of southern part of the island show that severe changes in coastal line from erosion and even witnessed the coastal cliff failure. In advanced countries, coastal engineers and researchers have studied deeply about this kind of problem for a long time. However, as it is not sot active in Korea and lack of research data, there exists difficulties on building protection methods and thoughtless constructions might make it more complicated and fatal to the coastal environment. In this study, we investigated some case studies of other countries and intended to induce and propose some integral protection methods for coastline erosion, considering environmentally sound and water friendly way of development such as artificial reef, floating breakwater, and double cellblock breakwater. Finally, we made analysis on the proposed methods with numerical model test and evaluation on the feasibility of each method.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.11-19
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• 2005

Traditionally Jeju island has a mild oceanic climate throughout the year and famous as worldwide resort area bacause of its pure natural environment and dramatic coastal scenery. But unpredicted coastal erosion problem, caused by variation of environmental conditions from construction of coastal structure and renovation of the existing ports, has raised its head above the water, and is becoming serious these days just like other coastal area in Korea. The phenomena happen here along the seaside of southern part of the island show that severe changes in coastal line from erosion and even witnessed the coastal cliff failure. In advanced countries, coastal engineers and researchers have studied deeply about this kind of problem for a long time. However, as it is not sot active in Korea and lack of research data, there exists difficulties on building protection methods and thoughtless constructions might make it more complicated and fatal to the coastal environment. In this study, we investigated some case studies of other countries and intended to induce and propose some integral protection methods for coastline erosion, considering environmentally sound and water friendly way of developement such as artificial reef, floating breakwater, and double cellblock breakwater. Finally, we made analysis on the proposed methods with numerical model test and evaluation on the feasibility of each method.

• Journal of Environmental Impact Assessment
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• v.27 no.1
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• pp.83-91
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• 2018

Media (bio-stone), aquatic macrophytes (Oenanthe javanica) and herbivorous cladoceran (Daphnia similoides) have been used in artificial floating island (AFI) systems for water pollution control. Efficiency in chl-a concentration controlling of AFI was tested using different combinations of each device: G-BD-mixture bio-stone and Daphnia similoides, G-OB-mixture Oenanthe javanica and bio-stone, G-BOD-mixture bio-stone, Oenanthe javanica and Daphnia similoides, and the out-put water quality improvement was compared with G-C-control (no device was applied). We analyzed removal efficiency of chl-a concentration and nutrient concentrations in the artificially eutrophic water in the laboratory experimental facility. The results showed average removal rates of Chlorophyll a, TN and TP for different four groups: 69.24%, 16.61%, -0.61%; 68.39%, 14.11%, 10.52%; 78.30%, 6.69%, 25.09%; 35.42%, -3.47%, -25.18%, respectively. The results have suggested that the mixture of media, plants and zooplankton is the most efficient combination for Chlorophyll a control, while the mixture of macrophytes and bio-stone have better efficiency nutrient control.

• Journal of Advanced Navigation Technology
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• v.23 no.5
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• pp.333-338
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• 2019

Satellite communication is not used by many people like mobile communication, but it is a necessary technology for public service and communication services, such as providing the Internet in military, disaster, remote education and medical services, island areas, and infrastructure vulnerable areas. However, most communication modems have problems with two-way communication with server as IP addresses are assigned to floating IP that change every time they communicate with the network. In this paper, we used the Raspberry Pi as the controller of the terminal device to communicate the network through the satellite modem and the PPP protocol, and to solve the problem of the modem with the floating IP, we used the text message function of the satellite modem. Through this process, two-way data links using the Thuraya geostationary orbit satellite were implemented.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.5
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• pp.29-43
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• 2020

Thermal environment of city is getting worse due to severe urban heat island caused by climate change and urbanization. The cooling effect of street tree is regarded as a effective way to ameliorate the urban heat environment. The effect is largely made up of shadow formation and transpiration. This study aims to identify how the transpiration affects the discomfort index by analyzing comprehensive impact of the transpiration on the air temperature and relative humidity. The changes in the amount of transpiration, air temperature, and relative humidity were estimated for Seogyo-dong area which has a lot of floating population in Seoul, at 2 p.m. in dry day in July and August. On average, the transpiration of the street tree decreased the temperature 0.3℃ and increased the relative humidity 2.6% in an hour. As a result of these changes in temperature and humidity, the discomfort index rose mostly(0.036 on average). It was always get rise especially on the day when the discomfort index was above 80(0.05 on average). However, compared with the significant change in temperature and humidity, the variation of the discomfort index itself was very slight(up to 0.107). Therefore, the effect of transpiration by the street trees might not be effective in the planning to improve the thermal environment(especially on the day when the discomfort index is high). It is necessary to select the species of trees and planting location considering the cooling effect of shade formation synthetically.

• Korean Journal of Environment and Ecology
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• v.32 no.4
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• pp.425-439
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• 2018

W investigated the environmental factors and inhabiting biota such as macrophytes and zooplankton in 43 sites located on Jeju Island from May and June 2017 to evaluate the spread and ecosystem risk of dotted duckweed (landoltia punctata) which was recently found for the first time in Jeju Island. Dotted duckweeds were found in a total of 18 sites which tended to show low biomass of aquatic macrophyte species other than the dotted duckweed. We conducted a pattern analysis using SOM (Self-Organizing Map), which extracts information through competitive and adaptive properties, to analyze the effect of inhabiting biota on aquatic macrophytes such as the dotted duckweed and environmental factors. The SOM analysis showed that the inhabiting biota such as the zooplankton affected the biomass of aquatic macrophytes than they did the environmental factors. In particular, the biomass of dotted duckweed was positively related to plant-attached species (Alona, Chydorus, and Pleuroxus). Considering that low density of aquatic macrophytes covers the streams and wetlands on Jeju Island because of irregular water source and sharp change of water depth, the dotted duckweeds are likely to play an essential role as the vital habitat for micro-biota including zooplankton in wetlands and streams on Jeju Island. Furthermore, considering that organic matters are utilized as the primary food source in the areas occupied by dotted duckweed, dotted duckweeds have the role of being both habitat and food source. Although the dense growth of dotted duckweed adversely affects growth and development of some aquatic plants due to the shadow effect, it is due to the dominance of floating plants on the water surface should not be regarded as the risk of the dotted duckweed. In conclusion, the dotted duckweeds have spread and settled in most of the water systems on Jeju Island, their impact on inhabiting biota and the aquatic environment was minor. It is necessary to monitor the distribution and spread of dotted duckweeds in the inland areas outside of Jeju Island in the future.

• Korean Journal of Remote Sensing
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• v.33 no.1
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• pp.97-109
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• 2017

Green tides that developed along the coast of China in 2015 were detected and tracked using vegetation indices from GOCI and Landsat images. Green tides first appeared near the Jiangsu Province on May 14 before increasing in size and number and moving northward to the Shandong Peninsula in mid-June. Typhoon Cham-hom passed through the Yellow Sea on July 12, significantly decreasing the algal population. An algae patch moved east toward Korea and on June 18 and July 4, several masses were found between the southwestern shores of Korea and Jeju Island. The floating masses found in Korean waters were concentrated at the boundary of the open sea and the Jindo cold pool, a phenomenon also observed at the boundary of coastal and offshore waters in China. Sea surface temperatures, derived from NOAA SST data, were found to play a role in generation of the green tides.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.10a
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• pp.42-42
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• 2018

Two unrecognized species of Sparganium of Korea were found during the our field expeditions and phylogenetic analyses of specimens deposited in the Herbarium of Korea National Arboretum (KH). S. coreanum H. $L{\acute{e}}v$. was first reported as a new species based on the specimen (Taquet, 2150) collected from Jeju Island. It has been recognized as synonym or infraspecific taxa of S. stoloniferum and S. eurycarpum or even never recognized recently. However, phylogenetic tree showed that S. coreanum is monophyletic and has sister relationship with S. eurycarpum. Furthermore, additional distribution localities were also found by herbarium survey. Morphological characteristics and distribution information of S. coreanum will be discussed. Another Sparganium species found from Mt. Daeam is occurring either as floating or emergent. Although we could not identify this species since lack of any flowers or fruits for two year surveys, phylogenetic analyses results showed that this species belong to the clade of S. glomeratum, which is distributed in high elevation lakes and marshes of Europe, Asia, and North America. Additional survey of morphology and report will be needed.