• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.371-377
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• 2000

Environmental impact on a land reclamation project, Hwaong tidal barrier was studied using the dispersion and advection model to predict the influence of polluted water discharged from freshwater reservior. The simulation results show that the distribution of concentration by influence of polluted water discharged during a tidal cycle appeared to be extinguished at atmost all points after two tidal cycle. Peak concentration near the sluice gate is found out to be higher during the spring tide than neap tide. Equi-concentration contour line appeared to distributed a longer according to line of sea dike in spring tide than neap tide. The reasons is because influence by currents of northwest direction is a stronger, compared to spring tide and neap tide in the flood tide.

• Ocean and Polar Research
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• 제30권1호
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• pp.1-10
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• 2008

In order to find the effect of intertidal sediments on nutrient cycle in coastal environment, we measured ammonia, nitrate, phosphate, and silicate concentrations every hour during at least 12 hours in the entrance of Keunso Bay during four seasons. The content of ammonia and silicate do not change considerably with season, but nitrate shows large seasonal variation. In summer, nitrate concentration was much lower than in other seasons, which resulted from large biological uptake and active denitrification in intertidal sediments during summer. Phosphate also exhibit seasonal variations, but not that large like nitrate. N/P and N/Si ratios were lower in summer than in other seasons, which was due to active denitrification in the intertidal sediments during summer. For all seasons, ammonia concentrations were higher at low tide than at high tide, but nitrate concentrations were higher at high tide. Dissolved inorganic nitrogen concentrations measured in spring, summer, and winter were higher at high tide than at low tide, but in fall, they were higher at low tide than at high tide. For spring and winter, phosphate and silicate concentrations were higher at low tide than at high tide, while in summer and fall, they were higher at high tide than at low tide. In Keunso Bay, intertidal sediments affect significantly the nutrient cycle around the coastal areas. The intertidal sediments act as a source for ammonia and silicate, but as a sink for nitrate. However, phosphate is not considerably influenced by intertidal sediments.

• 한국환경과학회지
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• 제5권4호
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• pp.473-479
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• 1996

The temnoral variations of the suspended material concentration (SMC) during spring-neap tidal cycle was investigated at more than 30 stations in Deukryang Bay, Korea, in 1 and 23 July, 1992. The averaged total SMC in spring tide was two times more than those in neap tide. It can be explained that the strong tidal current in spring tide disturbed bottom waters and induced higher SMC in the bay. The areal distributions of SMC for the surface and the bottom layers in the bay shows much different patterns during spring and neap tidal cycle. We concluded that the vertical stratification intensity of water mass is important factor of the horizonatal distribution of SMC in the bay.

• 한국어류학회지
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• 제28권3호
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• pp.192-199
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• 2016

조류에 의한 에너지가 상대적으로 매우 큰 한강 하구역의 대표적인 석모수로와 염하수로에서 2007년 8월과 2008년 8월에 연속 관측을 통해 조석주기에 따른 소하성 어종인 웅어속 자치어의 출현량을 조사하였다. 조석주기에 따른 환경측정 결과, $1^{\circ}C$ 미만의 수온차를 보였고, 염분은 창조 시 최고 15.1 psu, 낙조 시 최저 0.8 psu로 조석에 따른 염분차가 컸다. 웅어속 자치어는 창조 시보다 낙조 시 높은 출현량을 보였다 (p<0.05). 이는 소하성 어종인 웅어속 자치어가 한강 상류 또는 중류에서 부화한 후, 보육장인 하구역에 정착하기 위해 수평이동 선택적 조수흐름 (STST)으로 낙조류를 이용하는 것으로 사료되며, 특히 낙조 시 13.6 mm 이상의 유영력이 향상된 개체일수록 뚜렷하게 나타났다.

• 한국지구과학회지
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• 제37권7호
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• pp.465-475
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• 2016

본 연구에서는 전구에 걸쳐 나타나는 대기의 일주기 및 반일주기 조석을 최신의 3시간 간격 재분석자료를 이용하여 분석하였다. 선행연구들과는 달리 조석의 공간구조 및 계절성에 대한 분석이 표면으로부터 성층권에 걸쳐 수행되었다. 대부분의 층에서 일주기 조석은 중위도 지역에서 강한 반면, 반일주기 조석은 열대 지역에서 지배적으로 나타난다. 일주기 조석은 각 반구의 겨울철보다 여름철에 그 크기가 강하게 나타나는 강한 계절적 변동성을 보인다. 반면에 반일주기 조석은 계절적 변동성을 보이지 않는다. 반일주기 조석은 연직구조를 거의 가지지 않으나, 일주기 조석은 높이에 따라 그 크기가 증가하는 뚜렷한 연직구조를 가진다. 특히 열대지역 일주기 조석은 표면과 자유 대류권, 상층 성층권에서 거의 반대의 위상을 보인다. 그 크기 역시 고도에 따라 비선형적으로 변화하여 수증기, 오존, 중력파 그리고 태양복사에 영향을 받았을 가능성을 시사한다.

• 한국항해학회지
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• 제9권1호
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• pp.41-81
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• 1985

Tidal phenomenon can be utilized by the wise and cautious mariner to safely perform his duties as pilot and navigator. It can be either a help or hindrance to the mariner. The principle of MULDAE which expresses the determination of the state of the tide based upon knowledge of the lunar date and it has been used in Korea since ancient times. The folk method of calculation was essentially based on an unsystematic division of the lunar month, traditionally using the numbers 7 or 8. As the lunar cycle is complete in 15 days the tidal cycle should also correspondence closely to the lunar date. This paper represents the first scientific attempt to systematically investigate this unique traditional method of tidal calculation and contains a comparison of the MULDAE and ordinary (solar based) tide calculation methods. MULDAE was compared with the standard tide table for standard and island ports in Korea from 1982 to 1985. This study concluded that MULDAE was indeed an accurate adn reliable predictor of tidal activity. Furthermore, the number 6 was found to be the correct divisor upon which to base MULDAE calculations Also a formula expressing MULDAE as a function was discovered. This research show that MULDAE can be applied nationwide and is a reliable and easy way to predict tides based upon mean figures for certain ports and island A calender showing MULDAE is presented here for the first time. A clear relationship between the MULDAE method of calculating tides and the use of ordinary tide tables is proven.

• ALGAE
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• 제25권1호
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• pp.37-44
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• 2010

A tide-simulating apparatus was developed for culturing marine macroalgae. The objective of this study was to introduce a novel tide-simulating apparatus that can simulate a diurnal or semi-diurnal tidal cycle in the laboratory. In this apparatus, the seaweeds are move up and down and the water level remains the same during the simulated tidal cycle. The apparatus consists of 18 cylindrical culture tanks (3 blocks $\times$ 6 culture tanks) with 12 cm diameter and 24.5 cm long containing up to 2.5 L of seawater. There is a horizontal plate which covered all 18 culture tanks, and it is raised and lowered by a programmable motor that can regulate exposure time. In one application, seaweeds are attached to braided twine hung on Plexiglas air-tubing. The air-tubing is attached to a lid that is set on a horizontal plate. This apparatus is made of colorless Plexiglas to maximize light transmittance. This apparatus is easily disassembled and transportable to any indoor laboratory, wet laboratory, greenhouse, etc. This apparatus also offers considerable flexibility in terms of design. The size of culture tank can be redesigned by either increasing the height of cylinder or/and using a different diameter of cylindrical Plexiglas, therefore, larger/taller thalli can be cultivated. Growth rates of three eulittoral Porphyra species from different tidal elevations have been compared using this device.

• 수산해양기술연구
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• 제26권4호
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• pp.353-359
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• 1990

물리적, 지형적 특성으로 구성되고 있는 만내수괴의 유출입 구조와 해수의 교환능력을 정량적으로 구하기 위해, 진해만과 그 부속 내만을 대상으로 하여 현지관측에 근거해서 다음과같은 결과를 얻었다. 1. 가덕수도 단면의 유출입 특성은 유출수괴의 유축은 1조석주기동안 남북으로 2회 왕복운동을 진행하며, 대체로 하층에 존재한다. 유입수괴의 유축은 남부와 북부에 양분되어 존재하는 경향이다. 전 시간에 걸쳐 반류현상으로 보이는 유출입 수괴가 동시에 존재한다. 2. 양 수도를 통한 해수유출입량의 비율은 가덕수도에서 대조기 약 86~90% 소조기 61~80%유출입된다. 따라서, 가덕수도를 통한 수괴의 유출입이 만의 해수교류.교환을 지배한다. 3. 하계만의 해수교환율은 양 수도에서 대조기 12~13%, 소조기 20%이상이나, 마산만 입구에서는 대조기 9%, 소조기 2%정도에 불과하다. 4. 하구역 특성으로 본 해수교환기구는, 가덕수도가 흐름은 깊이에 따라 방향이 변하고 약간 성층되나, 잘 혼합된 염분분포를 나타내어 salt flux는 주로 이류에 의존한다. 마산만은 sill의 해저지형가 만 입구에서 tidal trapping 현상으로, 고도의 성층된 상태를 보이고 있다.

• 한국환경과학회지
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• 제11권6호
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• pp.519-528
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• 2002

This study was to evaluate the impact of river runoff and salt intrusion by tide on nutrient balance of estuary during a complete tidal cycle. 24 hours time series survey was carried out during a spring tide July 2001 on a tidal estuary in the Keum river. Three stations(A,B,C) were set along a transect line of about 10km, which linked the lower part of estuary dyke to the subtidal zone. Surface water was sampled simultaneously at each station every hours f3r the determination of nutrients. Water temperature, pH and dissolved oxygen were measured in situ. Riverine input of silicate and nitrate during ebb tide significantly increased the concentration of all stations. Conversely, during high tide, nutrient concentration were lowered by the mixing of fresh water with sea water Ammonium nitrogen concentration were higher at intertidal zone(Stn.B) due to sewage inflow to Kyeongpo stream and ammonium release under anaerobic conditions. Also, these results was discussed as a biological component that influences the processes of nutrient regeneration within the estuary. Best correlations were found at lower part of estuary dyke(Stn.A) for salinity against DIN(Y=0.121 Sal.+4.97, r2=0.956) and silicate(Y=0.040 Sal.+2.62, r2=0.785). But no significant correlation was found between salinity and ammonium. Unbalanced elemental ratio(N/P, Si/N and Si/P) depended significantly on the import of nutrients (silicate & nitrate nitrogen) from river and stream. The effect of the tidal cycle and river runoff is important that in determining the extend of the variations in nutrient concentrations at all station.

• 한국농공학회논문집
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• 제55권2호
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• pp.1-8
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• 2013

This study was performed for the purpose of analyzing the effect of tide on the stress-strain behavior in the boundary surface of sea dike embankment. Tide is a dynamic condition, but there are not suitable numerical models to solve the dynamic embankment condition caused by tide. So the analysis was simplified to quasi dynamic as follow. First, seepage by tide was analyzed according to elapsed time, and the results of the analysis at every hour during one periodic cycle time of 12 hours were applied to the pore water pressure conditions of stress-strain analysis with hyperbolic model by Duncan and Chang. The place at which maximum shear strain took place in the analysis result moved up and down repeatedly along the boundary of the dredged sand fill section and the crashed stone filter section. The value of maximum shear strain was large at high water level of tide. This result means that contraction and relaxation occur in turn repeatedly at every specific position along the boundary, and the repeated action compact loose position with sand moved down from the upper position by gravity. The experiment with the small sea dike model showed the result consistent with the numerical analysis. The surface of sea side on the dike collapsed at high water level after a couple of repetition of the rising and falling of water.