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  • Title/Summary/Keyword: Tidal Current Environment

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Initial and Near-field Dilution at the Ocean Outfall of Masan-Changwon Municipal Wastewater Treatment Plant(II) (마산ㆍ창원 하수종말 처리장의 해양방류 처리수에 대한 초기ㆍ근역 희석연구(II))

  • Kang See Whan;You Sung-Hyup;Oh Byung-Cheol;Park Kwang-Soon
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.3 no.1
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    • pp.35-44
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    • 2000
  • The winter case of the near-field dilution at the Masan outfalls has been studied by field measurements and CORMIX model simulations. Dilution rates of the wastewater discharge in winter were obtained by a salinity deficit method using the field data observed in the neap tidal period of February, 1999. The observed dilution rates in winter season were found to be very high in the range of 90~130 due to the isopycnal mixing of ambient density compared with the summer range of 30~40 under weak neap tidal currents. The results of CORMIX model simulations also show that the winter dilution rates under a weak ambient current(Ua=6.0ms/s) were increased by 3-fold of the summer dilution rates. However, the difference between two seasons becomes small by 30% under a strong current(Ua=15.5cm/s). This result indicates that the dilution and hydrodynamic mixing process of the effluents are more influenced by ambient crossflow condition than by ambient density stratification at the outfalls site.

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A Study on the Distribution of Summer Water Temperatures of the Central Coast of the Southern Sea of Korea Using Numerical Experimentation (수치실험을 이용한 남해 중부 연안의 하계 수온 분포 연구)

  • Choi, Min-Ho;Seo, Ho-San;Kim, Dong-Sun
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.23 no.1
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    • pp.83-90
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    • 2017
  • To understand the spatial-temporal distribution of seawater in Korea's South Sea, seawater movement and the distribution of water temperature has been analyzed using a hydrodynamic model (the Princeton Ocean Model). The directions of tidal currents were generally westward during flood tides and eastward during ebb tides. Northeastward Tsushima Warm Currents in the open sea, which is deeper than 50m were stronger than in coastal areas. Analysis of data from the hydrodynamic model showed that the water temperature in the semi-closed bay was relatively higher (2628C) than in the open sea (1822C). The exchange volume of semi-closed seawater was 10,331m3/sec in Gwangyang Bay, 16,935m3/sec in Yeosu-Gamag Bay and 13,454m3/sec in Geoje-Hansan Bay. Therefore, it was shown that the lower seawater exchange volume is, the higher seawater temperature will be.

Repair of Seonjingang Bridge in Namhae Highway Route Deteriorated by Chloride Attack (남해고속도로 섬진강교 내염보수공사 시공)

  • Han Bog Kyu;Chi Han Sang;Cheong Hai Moon;Ahn Tae Song
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.355-358
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    • 2005
  • Corrosion of reinforced concrete structures in marine environment is one of the most important mechanisms of deterioration. Under Korean highway bridge, the time for the steel reinforcement in the concrete to exhibit initial signs of corrosion is within three decades. Therefore, 'SUM JIN' highway bridge, located in a corrosive marine environment on the south of Korea, had been examined the current condition of the steel reinforcement corrosion in concrete by half-cell potentials, chloride contamination of concrete and so on. According to the tests, the protecting film around the reinforcement is deteriorated and corrosion activity developed in tidal zone. The purpose of this paper is to report the effects of 'SUM JIN' highway bridge damaged by chlodide attack and to present the results of repair of 'SUM JIN' highway concrete bridge in domestic marine environment.

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Static and dynamic mooring analysis - Stability of floating production storage and offloading (FPSO) risers for extreme environmental conditions

  • Rho, Yu-Ho;Kim, Kookhyun;Jo, Chul-Hee;Kim, Do-Youb
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.2
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    • pp.179-187
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    • 2013
  • Floating production storage and offloading (FPSO) facilities are used at most of the offshore oil fields worldwide. FPSO usage is expected to grow as oil fields move to deeper water, thus requiring the reliability and stability of mooring wires and risers in extreme environmental conditions. Except for the case of predictable attack angles of external loadings, FPSO facilities with turret single point mooring (SPM) systems are in general use. There are two types of turret systems: permanent systems and disconnectable turret mooring systems. Extreme environment criteria for permanent moorings are usually based on a 100-year return period event. It is common to use two or three environments including the 100-year wave with associated wind and current, and the 100-year wind with associated waves and current. When fitted with a disconnectable turret mooring system, FPSOs can be used in areas where it is desirable to remove the production unit from the field temporarily to prevent exposure to extreme events such as cyclones or large icebergs. Static and dynamic mooring analyses were performed to evaluate the stability of a spider buoy after disconnection from a turret during cyclone environmental conditions.

Fresh Water Flume Analysis Using an Unstructured Grid Ocean Circulation Model (비정규격자계 해양순환 모델을 이용한 하구에서의 담수 유출분석)

  • Hwang, Jin-Hwan;Park, Young-Gyu
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.12 no.4
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    • pp.227-234
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    • 2009
  • Using a finite volume ocean circulation model based on an unstructured grid (FVCOM), we studied the structure of a fresh water bulge that influences on the Region Of Freshwater Influence. Fresh water discharged a river forms a coastal boundary current to the righthand side and a cyclonically circulation freshwater bulge that grows with time. In the middle of the bulge, vertical motions bring fresh water to the bottom. When tidal motions are included, the bulge disappears while the boundary currents becomes wider. Through a simple comparison of areas occupied low salinity water we quantified vertical and horizontal mixing due to the tide and showed that the tidal motion enhances the vertical mixing. During the first few tidal cycles right after the onset of the river discharge, due to tidal excursion the horizontal mixing becomes stronger. The vertical mixing by the tide mixes the fresh water After a certain time the water around the river mouth is well mixed and the horizontal excursion of the fresh water near the river mouth does not have much effect on the horizontal mixing. When there is no tidal motion horizontal mixing is mainly by the inertial instability at the surface and the horizontal mixing becomes stronger over time.

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Ram pressure stripping conditions : Theory vs. Observation

  • Lee, Seona;Sheen, Yun-Kyeong;Yoon, Hyein;Jaffe, Yara;Chung, Aeree
    • The Bulletin of The Korean Astronomical Society
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    • v.45 no.1
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    • pp.33.1-33.1
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    • 2020
  • Ram pressure stripping (RPS) which is known to be one of the key effects that can remove the interstellar gas in the dense environment, can be described as a simple momentum transfer relation (Gunn & Gott 1972). However, it has been suggested that the actual gas stripping process is likely more complicated than Gunn & Gott's prescription due to the complexity of gas physics such as compression, cooling and heating. By comparing the gas truncation radius predicted by theory with the stripping radius measured from the HI observation of Virgo cluster galaxies, we attempt to verify how well the RPS process can be understood by momentum transfer alone. Among the sample of galaxies undergoing active RPS, we generally find a good agreement between what is predicted and what is observed within the measurement uncertainties. However, those galaxies with the signs of other environmental effects than RPS such as tidal interaction, and/or the ones likely at relatively early or later stages of RPS show some offsets between the theory and the observation. These results imply that Gunn & Gott's formula works reasonably well in a broad sense when the RPS is a dominant process and the surrounding environment at the current location of the sample can be well defined. Otherwise, the impact of the second mechanism, as well as the (current and past) environment of the sample, should be more carefully reviewed to assess the impact of RPS on galaxy evolution.

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Characteristics Variation of the Sedimentary Environment in Winter Season around the Baramarae Beach of Anmyeondo Using Surface Sediment Analysis (표층퇴적물 분석을 통한 동계 안면도 바람아래해수욕장 주변의 퇴적환경 변화특성)

  • JANG, Dong-Ho;KIM, Jang-Soo;PARK, No-Wook
    • Journal of The Geomorphological Association of Korea
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    • v.17 no.1
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    • pp.15-27
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    • 2010
  • This study investigated the sedimentary environment changes in the Baramarae beach of Anmyeondo through spatio-temporal surface sediment analysis. In the winter season 2009, surface sediments were classified into 7 sedimentary facies such as gravel, sand, gravelly sand, gravelly muddy sand, muddy sand, silty sand, and sandy silt. Time-series analysis of average grain size from 2002 to 2009 revealed that the average grain size of sediments became finer and sorting was much worse. On the contrary, during the same period, the grain size became coarsening-trend and sorting was much better in beach area. These different grain size patterns resulted from the different change characteristics of beach and tidal flats. The southwestern beach area was connected to the open sea and thus fine sediments were removed by the environments with relatively high-energy. The sedimentation of fine sediments in the bay resulted from the tidal current action and the reduction of energy by the topographic effects. Fine sediments in the outer part of southwestern tidal flats could be explained such that the Seomot isle blocked ocean waves and as a result, low-energy environments accelerated sedimentations of fine sediments.

Sediment Distribution of the Yeosu Sound on the Southern Coast of Korea Based on the 3.5 kHz Profiles (3.5 kHz 지층단면도에 나타난 여수해만의 퇴적물 분포)

  • 오진용;이연규;윤혜수;김성렬;최정민
    • Economic and Environmental Geology
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    • v.33 no.5
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    • pp.425-434
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    • 2000
  • The 3.5 KHz seismic survey was carried out for studying the distribution pattern of the unconsolidated sediments of the Yeosu Sound on the southern coast of the Korean Peninsula. Field data originally recorded in analog are converted and processed digitally to recover the high-resolution acoustic profiles. Across the north-south trending channel with the depth of 20~30 m, different seismic facies types are observed in the top section of sediments. The western part is characterized by the continuous high-amplitude subparallel reflectors within which the acoustic turbidity as a token of the presence of gas is commonly observed, whereas the counterpart largely shows poor reflectors and has shallow acoustic basement toward the north. The dissimilarity of the seismic expression across the channel can be interpreted as the result of the change of depositional environment caused by relative sea-level fluctuations of the late-Quaternary. During the last glacial period, the Yeosu Sound was exposed and eroded by the paleo-Seomjin River. By the following rapid rise of sea level, it was covered by the transgressive sand sheet. When the sea level reached near the present position, the muddy sediment has accumulated only in the western part of the Yeosu Sound as its depositional front has moved toward the north. It is partly caused by the asymmetrical tidal current in the Yeosu Sound where the flood near the bottom has stronger current flow and contains more suspended sediments.

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Assessment of the potential for the design of marine renewable energy systems

  • Duthoit, Maxime;Falzarano, Jeffrey
    • Ocean Systems Engineering
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    • v.8 no.2
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    • pp.119-166
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    • 2018
  • The assessment of the potential for the design of marine renewable energy systems is reviewed and the current situation for marine renewable energy is promising. The most studied forms of marine renewable energy are ocean wind energy, ocean wave energy and tidal energy. Wind turbine generators include mostly horizontal axis type and vertical axis type. But also more exotic ideas such as a kite design. Wave energy devices consist of designs converting wave oscillations in electric power via a power take off equipment. Such equipment can take multiple forms to be more efficient. Nevertheless, the technology alone cannot be the only step towards marine renewable energy. Many other steps must be overcome: policy, environment, manpower as well as consumption habits. After reviewing the current conditions of marine renewable energy development, the authors analyzed the key factors for developing a strong marine renewable energy industry and pointed out the huge potential of marine renewable energy.

Oil Spill Behavior forecasting Model in South-eastern Coastal Area Of Korea (한국 동남해역에서의 유출유 확산예측모델)

  • Ryu Cheong Ro;Kim Jong Kyu;Seol Dong Guan;Kang Dong Uk
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.1 no.2
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    • pp.52-59
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    • 1998
  • Many concerns are placed on preservation of coastal environment from the spilled oil contaminant in the coastal area. And the use of computer simulation model to combat with oil spill has come to play mote important role in forecasting the oil spill trajectory so as to protect coastal area and minimize the damage from oil contaminants. The main concerns of this study is how the movements of spilled oil are affected by currents including tidal, oceanic, and wind-driven currents. Especially, in the present paper, the oil spill trajectory can be predicted by a real-time system that allows prediction of circulation and wind field. The harmonic methods are adopted to simulate the tidal currents as well as it can be possible to achieve the wind-field data and oceanic current data from the established database. System performance is illustrated by the simulation of oil spill in the south-eastern coastal area of Korea. Simulation results are compared with the observed one.

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