• The Journal of Engineering Geology
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• v.10 no.2
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• pp.150-171
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• 2000

In the Cheju Island, there are high salinity water yield in the coastal area. There are various reason; the main reason is low-groundwater level by the structure of geology, and over-yielding etc. This study analysis water quality, the distribution of high salinity wells. 16 sample well logged the electronic geology survey. As result of distribution of Cl$^-$ is the East Area is high than other areas. Water quality test data divides 6 group by sea level of well bottom: over Om, Om~-1Om, -10~-20m, -20~-30m, -30~-40m, under -40m. According collect data of Kriging, and logged the electronic geology survey, and other survey are related chlorine(Cl$^-$). The map of Cl$^-$ distribution was made. Bukcheju Gun, Hallim Up, there are 2 wells prevent high salinity water. Both of well are effective grout sill salinity water intrusion aquifer.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.1-12
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• 2010

The objective of this study was to examine the hydrogeochemical and microbiological characteristics for stable maintenance of coastal LPG storage cavern. Cavern seepage water and groundwater in the vicinity of the LPG storage cavern were sampled and analyzed (February, May, August and October 2007). Groundwater samples of propane cavern showed high pHs of 8.1~12.4 due to dissolution of cement grouting materials that had been applied during the well and cavern construction. The EC values showed distinctive seasonal variation. The negative ORP indicated reduced condition. The seepage and surrounding groundwater are classified as Na-Cl type, which represents seawater effects. All of aerobic bacteria, anaerobic bacteria, slime forming bacteria and sulfate reducing bacteria were less than 500 CFU/mL, which indicated that there was no abrupt increase of bacteria in the cavern. Therefore there exist no hydrochemical symptoms to indicate unstable conditions of the cavern operation. However, regular and continuous monitoring is essentially required.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.93-102
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• 1997

Coastal circulations during the (surface condition of an) idealized cold-air outbreak are numerically investigated with two-dimensional, non-hydrostatic model in which a constant bottom-slope exists. The atmospheric forcing during a cold-air outbreak is incorporated as the surface cooling and the wind stress. When the offshore angle of the wind-stress vector, defined as the angle measured from the alongshore axis, is smaller than 45 degrees, a strong downwelling circulation develops near the coast. A sharp density front, which separates the vertically homogeneous region from the offshore stratified region, is formed near the coast and propagates offshore with time. Onshore side of the density front, small-scale circulation cells which are aligned in the direction perpendicular to the bottom begin to develop as the near-coast homogeneous region broadens. The surface cooling enhances greatly the development of the surface mixed layer by convective motions due to hydrostatic instability. The convective motions reach far below the hydrostatically unstable layer which is attached to the surface. The small-scale circulation cells are appreciably modified by the convetion cell and the density front develops far offshore compared to the case of no surface cooling. As to the effect of the bottom slope, the offshore distance of the density front increases (decreases) as the bottom slope decreases (increases), which results from the fact that the onshore volume-transport (Ekman transport) of the low-density upper seawater remains almost constant when the wind-stress is maintained constant. It is shown that the bottom slope is an essential factor for the formation of both the density front and the alongshore current when the surface cooling is the only forcing.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.4
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• pp.320-328
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• 2007

The durability of marine concrete structures is severely degraded by corrosion due to seawater attack and diffusion of chloride in concrete. The deduction of durability causes high repair cost for maintenance of marine concrete structure. So, the applicability of high-durable materials is investigated to improve the durability in marine concrete structures. For these, the characteristics of corrosion prevention of marine concrete structures mixed with the mineral admixtures(SF, FA and BFS), the modified steel(stainless and coating steel), and corrosion inhibitors are evaluated using electro-chemical methods. As a results of this study, it is quantified for the effect of promotion of durability by high-durability materials in marine concrete structures.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.1
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• pp.48-54
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• 2020

Numerical analysis was carried out to analyze the flow fields and mechanical output of a rotor for various positions and inlet flow rates in a shroud, and it was compared with experimental data. Rotor and seawater current largely affects the flow field characteristics in the shroud system. Especially the mechanical output of the rotor increased with axial position near the center of the cylinder, and it gradually decreased close to the entrance and exit. Also, the rotor output increased with the inlet velocity. Axial and angular momentum of flow along the cylinder region rapidly increased and reached a peak, and then decreased as it passed through the rotor, while there was no significant change in the cylinder region. It is expected that these results can be used as applicable design data for the development of the tidal power generation system.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.1
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• pp.53-60
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• 2020

Due to global climate change, Korea is experiencing flooding and drought severely. It is hard to manage water resources because intensive precipitation during short periods and drought are commonly occurred in Korea, recently. Severe drought occurred in 2015 and 2017 in the islands, and coastal and inland areas in Korea, and the citizens experienced decreased water supply and emergency water service by using bottled water. Therefore, the Korean government provided additional governmental funds such as the grant of drought disaster. In this study, we tried to calculate the cost of water for drought response based on the cost of tap water for the regional local governments in Korea and the grant of drought disaster by the Ministry of the Interior and Safety in Korea, etc. The estimated costs of water for drought responses in coastal and inland areas which have a chance to apply alternative water sources such as brackish or seawater desalination and water reuse in Korea were higher than in other areas in Korea. Additionally, as the novel approach of drought response, the 300 ㎥/day-scale desalination vessel was suggested to provide desalinated water for the islands in Korea. The estimated expenses of water supply for the target island areas (Sinan-gun and Jindo-gun) by the desalination vessel was lower than those by emergency water service by using bottled water.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.32 no.6
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• pp.396-410
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• 2020

The design and the construction are carried out by installation of new caissons on the back or the front of existing caissons to increase the stability of existing caisson breakwater. In this study, we use the eigenfunction expansion method to analyze the effects of wave structure interaction when new porous dual circular caissons are installed on the back or the front of existing breakwater. The porous dual circular caisson which consisting of a porous outer cylinder circumscribing an impermeable inner cylinder is one type of seawater exchanging breakwater. The comparison of numerical results between present method and Sankarbabu et al. is made, and the wave force and the wave run-up acting on each porous dual circular caisson are calculated for various parameters by considering the wave structure interaction.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.1
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• pp.11-18
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• 2022

In order to improve the accuracy of particle tracking prediction techniques near the Korean Strait, this study compared and analyzed a particle tracking model based on a seawater flow numerical model and a machine learning based on a particle tracking model using field observation data. The data used in the study were the surface drifter buoy movement trajectory data observed in the Korea Strait, prediction data by machine learning (linear regression, decision tree) using the tide and wind data from three observation stations (Gageo Island, Geoje Island, Gyoboncho), and prediciton data by numerical models (ROMS, MOHID). The above three data were compared through three error evaluation methods (Correlation Coefficient (CC), Root Mean Square Errors (RMSE), and Normalized Cumulative Lagrangian Separation (NCLS)). As a final result, the decision tree model had the best prediction accuracy in CC and RMSE, and the MOHID model had the best prediction results in NCLS.

• 한국해양학회지
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• v.11 no.2
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• pp.89-95
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• 1976

Some factors of seawater such as water temperature, salinity, pH, dissolved oxygen and asturation of dissolved oxygen were determined in 5 meters intervals from surface to bottom at 11 stations in Yeongil Bay of Korea during late October 1973. Distribution pattern of water masses in Yeongil Bay during the period seemed to be heterogeneous as dividing into two parts of surface and bottom. Water temperature, pH, dissolved oxygen and saturation of dissolved oxygen of surface water mass showed higher values and salinity of the mass showed lower values than those factors of bottom water mass. Surface water mass might be originated from Tsushima current during summer season and bottom water mass from cold body of East Sea of Korea which seemed to extend to coastal zone during winter season. Land water discharge from Hyeongsan River into the Bay is considered as a minor factor playing slight role in the water mass composition of the area.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1960-1963
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• 2009

본 연구에서는 부산시 용호만 해안대수층에서 전기전도도와 지하수위의 수직적인 관측을 통해, 조석에 의한 해수/담수 경계면의 변동을 산정하였다. 연구지역은 부경대학교 대연캠퍼스 기숙사 신축부지 주변 해안대수층이며, 응회질퇴적암과 안산암 및 안산암질 화산각력암 등으로 구성되어 있다. 관측공의 개발심도는 120 m, 케이싱심도는 19 m, 내경은 0.2 m, 관측공과 해안선의 이격거리는 180 m 정도이다. 전기전도도에 의해 산정된 밀도는 담수에서 997.58 $kg/m^3$, 해수에서 1020.36 $kg/m^3$ 이었다. 관측기간(2008년 8월 21일${\sim}$10월 18일) 동안 해수/담수 경계면의 변동 범위는 해수면 기준 -21.69${\sim}$-21.53 m 이었으며, 경계면의 평균 위치는 해수면 기준 -21.62 m 정도이었다. 해수/담수 경계면과 지하수위의 상관성은 매우 높게 나타났으며, 해안대수층 내 해수/담수 경계면의 변동은 조석의 일(고조, 저조) 및 보름(대조, 소조) 단위의 변동에 영향을 받고 있음이 확인되었다. 관측기간 동안 지하수위는 전반적으로 하강하는 경향을 나타내었으며, 이는 관측기간이 풍수기에서 갈수기로 전환되고 있었기 때문이다. 향후에는 지속적인 관측을 통해, 용호만 해안의 해수면 상승에 의한 내륙으로의 해수침투를 연구하고자 한다.