• The Journal of Engineering Geology
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• v.33 no.1
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• pp.105-119
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• 2023

Water supply is decreasing due to climate change, and coastal and island regions are highly dependent on groundwater, reducing the amount of available water. For sustainable water supply in coastal and island regions, it is necessary to accurately diagnose the current condition and efficiently distribute and manage water. For a precise analysis of the groundwater flow in the coastal island region, submarine fresh groundwater discharge was calculated for the Seongsan basin in the eastern part of Jeju Island. Two methods were used to estimate the thickness of the fresh groundwater. One method employed vertical interpolation of measured electrical conductivity in a multi depth monitoring well; the other used theoretical Ghyben-Herzberg ratio. The value using the Ghyben-Herzberg ratio makes it impossible to accurately estimate the changing salt-saltwater interface, and the value analyzed by electrical conductivity can represent the current state of the freshwater-saltwater interface. Observed parameter was distributed on a virtual grid. The average of submarine fresh groundwater discharge fluxes for the virtual grid was determined as the watershed's representative flux. The submarine fresh groundwater discharge and flux distribution by year were also calculated at the basin scale. The method using electrical conductivity estimated the submarine fresh groundwater discharge from 2018 to 2020 to be 6.27 × 10⁶ m³/year; the method using the Ghyben-Herzberg ratio estimated a discharge of 10.87 × 10⁶ m³/year. The results presented in this study can be used as basis data for policies that determine sustainable water supply by using precise water budget analysis in coastal and island areas.

• Journal of Soil and Groundwater Environment
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• v.10 no.2
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• pp.12-19
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• 2005

Jeju island is one of the highest rainfall areas in the Korean peninsular. However, variation in rainfall amount is much great with years, which resulted in substantial variation in annual groundwater recharge and sustainable yield. Therefore, to cope with groundwater hazard including sea water intrusion and water level decline in accordance with successive extreme drought, Jeju province established a stepwise action system, in which management of representative monitoring wells and corresponding actions to water level conditions was enforced. In this study, rainfall and groundwater monitoring data were analyzed to determine management groundwater level on Jeju island. First, rainfall data for last 30 years were analyzed, which yielded a lower limit of rainfall at a confidence level of 99% as a basis rainfall. Only when the rainfall less than the basis rainfall was sustained over 3 months, the water levels were targeted for the analysis. For the water level data selected using the above criteria, the lower limit of 99% confidence interval was determined as a reference groundwater level. Finally, some ratios of reference groundwater level was determined as stepwise management groundwater level on Jeju island.

• Journal of the Korean association of regional geographers
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• v.18 no.2
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• pp.175-187
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• 2012

Geotourism is an essential sector of geopark, as it stimulates sustainable development, local socioeconomic development as well as educational effects, from which geo-scientific knowledge can be communicated between the local people and the public. It is also a rapidly growing paradigm of nature-based tourism and is attractive in terms of its year-round accessibility to the sites. Passing over a decade history, it is necessary to present how it can establish a platform for further development and improvement across the country. In this regard, this study is to demonstrate how to develop geotourism model that is effectively applicable to Korean environment based on the enhancement of geotourism. We apply the general geotourism organization model to Haegeumgang in Geojedo Island in this study. Although this area is well known for its small boat tours, privately-guided-tour on the boat is insufficient in terms of delivering geological and geographical information from the geotourism perspective. Therefore, in order to develop the desirable Korean geotourism model, boat tours at Haegeumgang have to be supported professionally by the local government through the geotourism department and the partnership with the stakeholders.

• Journal of Korean Society for Geospatial Information Science
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• v.19 no.2
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• pp.55-61
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• 2011

The land use has been changed artificially and caused the result of temperature increase of city compared with the outside of city or region of park and forest. The purpose of this research is to analyze the change of the urban surface temperature with land use zoning in Jinju using Landsat TM/$ETM^+$ imagery and to provide the correlation between NDVI(Normalized Difference Vegetation Index) and urban surface temperature change. The results presented that the spatial distribution of urban surface temperature was depending on the change of NDVI values on land use zoning. Considering to the average temperature by land use zoning, industrial area was the highest temperature but green area was the lowest temperature. Also as a result of comparing the correlation between surface temperature and NDVI, the green and residential area had higher correlation values than the commercial and industrial area. These results will be played a part as one of the major factors for implementing the sustainable urban planning considering the urban heat island effect problem.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.2
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• pp.107-112
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• 2008

To evaluate uncertainty and risk in biological reference points, we applied a bootstrapping method and a Bayesian procedure to estimate the related confidence intervals. Here we provide an example of the maximum sustainable yield (MSY) of turban shell, Batillus cornutus, estimated by the Schaefer and Fox models. Fitting the time series of catch and effort from 1968 to 2006 showed that the Fox model performs better than the Schaefer model. The estimated MSY and its bootstrap percentile confidence interval (CI) at ${\alpha}=0.05$ were 1,680 (1,420-1,950) tons for the Fox model and 2,170 (1,860-2,500) tons for the Schaefer model. The CIs estimated by the Bayesian approach gave similar ranges: 1,710 (1,450-2,000) tons for the Fox model and 2,230 (1,760-2,930) tons for the Schaefer model. Because uncertainty in effort and catch data is believed to be greater for earlier years, we evaluated the influence of sequentially excluding old data points by varying the first year of the time series from 1968 to 1992 to run 'backward' bootstrap resampling. The results showed that the means and upper 2.5% confidence limit (CL) of MSY varied greatly depending on the first year chosen whereas the lower 2.5% CL was robust against the arbitrary selection of data, especially for the Schaefer model. We demonstrated that the bootstrap and Bayesian approach could be useful in precautionary fisheries management, and we advise that the lower 2.5% CL derived by the Fox model is robust and a better biological reference point for the turban shells of Jeju Island.

• Journal of Appropriate Technology
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• v.7 no.2
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• pp.136-143
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• 2021

Pacific island countries, including Kiribati, are suffering from a shortage of essential resources as well as a reduction in their living space due to sea level rise and coastal erosion from climate change, groundwater pollution and vegetation changes. Global activities to solve these problems are being progressed by the UN's efforts to implement SDGs. Pacific island countries can adapt to climate change by using abundant marine resources. In other words, seawater plants can assist in achieving SDGs #2, #6 and #7 based on SDGs #14 in these Pacific island countries. Under the auspice of Korea International Cooperation Agency (KOICA), Korea Research Institute of Ships and Ocean Engineering (KRISO) established the Sustainable Seawater Utilization Academy (SSUA) in 2016, and its 30 graduates formed the SSUA Kiribati Association in 2017. The Ministry of Oceans and Fisheries (MOF) of the Republic of Korea awarded ODA fund to the Association. By taking advantage of seawater resource and related plants, it was able to provide drinking water and vegetables to the local community from 2018 to 2020. Among the various fields of education and practice provided by SSUA, the Association hope to realize hydroponic cultivation and seawater desalination as a self-support project through a pilot project. To this end, more than 140 households are benefiting from 3-stage hydroponics, and a seawater desalination system in connection with solar power generation was installed for operation. The Association grows and supplies vegetable seedlings from the provided seedling cultivation equipment, and is preparing to convert to self-support business from next year. The satisfaction survey shows that Tarawa residents have a high degree of satisfaction with the technical support and its benefits. In the future, it is hoped that SSUA and regional associations will be distributed to neighboring island countries to support their SDGs implementations.

• Korean journal of applied entomology
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• v.53 no.4
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• pp.375-380
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• 2014

The sweetpotato whitefly (SPW), Bemisia tabaci Gennadius, is a major pest in tomato greenhouses on Jeju Island because they transmit viral diseases. To develop practical sampling methods for adult SPWs, yellow-color sticky traps were used in commercial tomato greenhouses throughout the western part of Jeju Island in 2011 and 2012. On the basis of the size and growing conditions in the tomato greenhouses, 20 to 30 traps were installed in each greenhouse for developing a sampling plan. Adult SPWs were more attracted to horizontal traps placed 60 cm above the ground than to vertical trap placed 10 cm above the plant canopy. The spatial patterns of the adult SPWs were evaluated using Taylor's power law (TPL) and Iwao's patchiness regression (IPR). The results showed that adult SPWs were aggregated in each surveyed greenhouse. In this study, TPL showed better performance because of the coefficient of determination ($r^2$). On the basis of the fixed-precision level sampling plan using TPL parameters, more traps were required for higher precision in lower SPW densities per trap. A sequential sampling stop line was constructed using TPL parameters. If the treatment threshold was greater than 10 maximum adult SPWs on a trap, the required traps numbered 15 at a fixed-precision level of 0.25. In estimating the mean density per trap, the proportion of traps with two or more adult SPWs was more efficient than whole counting: ${\ln}(m)=1.19+0.90{\ln}(-{\ln}(1-p_T))$. The results of this study could be used to prevent the dissemination of SPW as a viral disease vector by using accurate control decision in SPW management programs.

• The Journal of Engineering Geology
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• v.34 no.2
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• pp.163-171
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• 2024

Changes in the soil layer on Dokdo are important both academically and with regard to sustainable conservation and utilization of the islands. Continuous investigation and observation are necessary, as the soil layer is essential to the growth of plants and, therefore, the islands' ecosystem. Such work was carried out for about 8 years using soil erosion measuring bars, which are durable and facilitate simple monitoring of changes in the soil layer. Each bar comprised a rod measuring 30~50 cm long and 1.5 cm in diameter, and the use of stainless steel afforded resistance to corrosion caused by sea breezes. Six measuring bars were installed in the soil layers of each of two islands, Dongdo and Seodo, and measurements were taken one to three times a year from 2014 to 2021. The field measurements indicate that soil was deposited on Dongdo but eroded on Seodo during the observation period. As the measuring bars on Dongdo were located in the central and lower parts of the island, the observed changes in the soil layer resulted mainly from sedimentation of material eroded by weathering or soil runoff from the upper part of the island. In contrast, the measurement locations on Seodo were located in the upper and central parts of the island, where soil erosion and runoff diminished the soil layer at the observation points.

• KIEAE Journal
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• v.11 no.1
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• pp.29-38
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• 2011

This study suggested practical application of climate design on apartment complex with the focus on the use of Cold Air Flow and green building design method. The domestic research on the wind path analysis has been associated since the early 21th century in urban planning and site planning, this initiative study aimed to mitigate the urban heat island effect and to promote the sustainable urban development. It is, however, mostly focused on the flow analysis and heat flow in the urban context, due to the poor application of the wind path analysis in actual planning and design. Special attention is paid to the possibilities of identifying and developing the application methods in relation to Cold Air Flow and building design. This study examined these relations and suggested some trenchant approach to a more comprehensive and efficient use of the wind flow analysis in climate design.

• KSBB Journal
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• v.24 no.1
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• pp.89-95
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• 2009

Biodiesel (fatty acid alkyl esters), which is produced from sustainable resources such as vegetable oil, animal fat and waste oils, have used to as substitutes for petro-diesel. In this study, we investigate the performance of 30 L and 300 L pilot-scale biodiesel production system using alkali-catalyst transesterification from soybean oil and rapeseed oil produced at Jeju island in Korea. The 30 L-scale biodiesel production was performed to in the condition of reaction temperature $65^{\circ}C$, catalyst amount 1% (w/w) and oil to methanol molar ratio 1 : 8. At that reaction condition, the fatty acid methyl ester contents of product are above 98% within reaction time 30 min. Also, the conversion yield of over 98% was obtained in 300 L-scale biodiesel production system using rapeseed oil and soybean oil. The quality of biodiesel produced from reaction system was satisfied to recommended quality standard of Korea. Our results may provide useful information with regard to the scale-up of more economic and efficient biodiesel production process.