• 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.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.155-162
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• 2010

Recently, due to high oil prices and environmental pollution issues, interest of alternative energy development increases and the related research is widely conducted. Among those research activities the tidal stream power generation utilizes the tidal flow as its mechanical power resource and less depends on the environmental condition for installation and operation than other renewable energy resources. Therefore the amount of power generated is quite consistent and straightforward to predict. However, research on the tidal stream energy conversion turbine is rarely found. In the present study, two numerical methods were developed and compared for the open water Momentum Theory, which is widely used for wind turbines, was adopted. The moving reference frame method for Computational Fluid Dynamis solver were also used. Hybrid meshing was used for the complex geometry of turbines. The analysis results using each method were compared to figure out a better method for the performance prediction.

• 환경영향평가
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• 제11권4호
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• pp.231-238
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• 2002

In this study we classified sediment types of tidal flat using Landsat-5 images. This is for groping the method which can analyze correctly various kinds of sediment faces through satellite images. This work was performed by referencing ground truth of sediment faces which was investigated in the field. With this data we classified Landsat-5 image of 1997's to grope a most suitable classification method. As a result, in case of south Kanghwa island area, it was the optimum way to compound band 4, 5, 7 of Landsat-5 TM imagery. And, this work classified 3 kinds of sediment faces - M(mud), sM(sandy mud) and (g)M(slightly gravelly mud) - in land and mixed water area. It is anticipated that if this method is applied to a image of extremely lower sea level time, it can classify the sediment types of a broad tidal flat area. This is expected to be a beginning of estimating the effect of sediment faces to the change of the tidal flat ecosystem.

• 한국해안·해양공학회논문집
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• 제25권3호
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• pp.165-171
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• 2013

조차가 큰 해역에서 조위편차 역시 크게 나타나고 있음은 조위편차 내에 조석성분이 남아있음을 의미한다. 상관관계함수를 통한 분석을 시행한 결과에서도 서해안 해역에서 조석주기 부근의 자기상관계수가 크게 나타나고 있어 이러한 사실을 뒷받침하고 있다. 조위편차의 단주기성분에 해당하는 이러한 조석관련성분을 분석하기 위하여 웨이블릿분석을 시행하였다. 분석 결과에 의하면 조차가 클수록 조석주기성분이 크게 나타나고 있으며 단주기 성분에서 계절별 변화가 심하지 않다는 점과 목포의 경우 천해조성분인 6시간 주기성분이 유독 크게 나타나고 있다는 점에서 단주기 성분과 조석관련성분의 관련성을 연관지을 수 있다. 이와 함께 24시간 이내 단주기 성분의 조위편차는 조석예측오차 및 조석-해일 비선형성 등에 주로 기인하고 있는 것으로 파악되었다. 이러한 조석변조해일성분은 조석자체에 기인하므로 기상조 성분인 해일고와는 구분되어야 한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2002년도 Proceedings of International Symposium on Remote Sensing
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• pp.664-669
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• 2002

Intertidal zone (tidal flat) is a place which is sometimes dry and sometimes wet depending on the tidal rhythm. Direct measurement of topography in the intertidal zone is very difficult to be achieved. The interface between wet and dry parts in the tidal flat, which can be identified from near infrared band of satellite image, is a 'depth contour' which corresponds to the sea level at the time of satellite pass. Aquisition of topography data in tidal flat is possible by combining various techniques such as (1) identification of the interface between wet and dry parts, (2) GCP correction of satellite image, and (3) realtime prediction of sea level elevation at the time of satellite pass. The algorithm was successfully applied in obtaining topography (bathymetry) data in the intertidal zone of Asan Bay in the west coast of Korea from 26 satellite images. The method is expected to be very efficient in making bathymetry data base in the western and southern parts of Korea where tidal flats are well developed in wide regions.

• 물과 미래
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• 제25권2호
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• pp.67-78
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• 1992

Several field surveys were conducted to investigate changes of water quality with time in a tidal river. Results indicated that nitrification process were dependent on the change of salinity and suspended solids concenttration. Therefore laboratory batch experiments were conducted, using suspended solids and sediment taken from a tidal river, to study the effect of salinity on nitrification and to estimate kinetic parameters of it in the tidal river. suspended solids and sediment were sampled at a point in the middle stream. Sediments were collect from the aerobic layer of mud. The change of nitrogen concentration with time was clearly explained with Monod groth model and kinetic parameters were obtained by curve fitting method. Changes in NH4-N, NO2-N, and NO3-N concentrations in the river ROKKAU with time were simulated well using Lagrangian reference frame and parameter values obtained in the laboratory tests. T도 mechanism of nitrification by suspended solids and sediment in a tidal river is shown to depend on tidal effects.

• 한국항만학회지
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• 제14권4호
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• pp.441-450
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• 2000

In order to improve the water quality in semi-enclosed bays, Gug et al. (1997) have proposed a new method to activate the tidal exchange by creation and control of tidal residual current through the addition of artificial elements to creation and control of tidal residual current through the addition of artificial elements to create bottom roughness, so, ot is advisable to arrange as few of these as possible from a point of cost-benefit view. This paper attempts to develop the most suitable shape of artificial bottom roughness units with which to create and control an optimal tidal residual current. Several simple shapes were examined as fundamental cases. Subsequently 38 types of artificial bottom roughness units based on a few simple effective shapes, were examined experimentally. As a result of this research, two types to create artificial roughness.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.1415-1417
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• 2003

In this study, as the passing of a year, the changes of tidal flat area in Seohan Bay, North Korea was monitored through using Landsat ETM Data and the ancient topological map. The map to present tidal flat distribution characteristic based on the ancient topographical map (1918) was constructed as GIS DB. In addition, a tidal flat distribution map was estimated by using the satellite images with unsupervised classification method. Even though it is difficult to approach to study area, it was possible to gain the data and to monitor the change of the coast tidal flat by comparing to area change yielded.

• 한국항만학회지
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• 제13권1호
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• pp.123-132
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• 1999

It is very important to quantitatively assess the movement of sea water and pollutant dispersion before or after constructing shore structures such as breakwater considering marine environment and long-term utilization of those structures. This assesment is possible through the use of simulation models designed to predict water movement and pollutant dispersion in a certain area. In this study the numerical computations were carried out to predict the sea water quality in the Ilgwang Harbor located at the east coast of Pusan. The flow patters were investigated before and after the development of Ilgwang Harbor. The computational models adopting ADI Method (Alternating Direction Implicit Method) were used here and were already verified from the previous studies. As a results of this study the tidal exchange in Ilgwang Harbor after development proved to be worse due to the increased semi-enclosed at the harbor limit. In order to improve the water quality of this area after development a new method was proposed to improve water quality in the semi-enclosed bay by creation and control of tidal residual currents. For this purpose the unsymmetric structures so called bottom roughness were introduced in this study. The simulation was carried out on the basis of the study by Komatsu et. al. and Gug and we made a conclusion that it is possible to generate a new tidal residual current and to increase the tidal exchange by application of bottom roughness arrangement.

• 대한지리학회지
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• 제45권2호
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• pp.275-292
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• 2010

이 연구는 위성영상 자료(1972~2008년)를 이용하여 인위적인 환경변화에 따른 태안반도 간석지의 토지피복 변화를 시계열분석하고, 그 변화 패턴을 고찰하고자 하였다. 선분류 후비교법을 이용한 시기별 토지피복 변화를 분석한 결과, 1972년에서 2008년 사이에 태안반도 간석지의 토지피복은 갯벌에서 습지, 습지에서 논으로의 변화가 발생하였다. 세부적인 토지피복 변화 패턴을 분석하기 위해 변형된 선분류 후비교법을 이용하여 각각의 영상을 분석한 결과 태안반도 간석지는 갯벌 $\rightarrow$ 습지 호수 및 염전 $\rightarrow$ 나대지 $\rightarrow$ 논 $\rightarrow$ 나대지로 변하였음을 분석할 수 있었다. 선분류 후비교법의 적용을 위해서는 각 영상의 정확한 분류가 반드시 요구되는데, 분류된 영상의 전체정확도는 평균 95.33%로 나타났고, 카파값은 평균 0.941로 나타났다.