• 한국해양학회지
• /
• v.18 no.2
• /
• pp.142-148
• /
• 1983

In order to understand the circulation dynamics of the Keum River estuary, an extensive study was conducted; (i) variability of salinity boundary layer (ii) fluid dynamic characteristics (iii) tides and tidal currents (iv) circulation, diffusion, and dispersion (v) numerical modelling. As first part of this series of work, the salinity data obtained at six sites by using instantaneous profil]ing technique were analyzed in detail. it is found that the amplitude of salinity variation increases toward the upstream direction and its magnitude is greater at neap tide than spring tide. And also duration of salinity boundary layer is much longer during the neap tide than the spring tide, As a result of this study, the Keum River estuary is classified as a typical standing wave type estuary. Finally, we present a schematic diagram for the duration of the salinity boundary layer, which will be useful for further study on flocculation phenomena and sedimentation dynamics.

• Journal of Fisheries and Marine Sciences Education
• /
• v.25 no.3
• /
• pp.733-742
• /
• 2013

The Korea has significant tidal current energy resources, but it is so hard to work underwater for tidal turbine installation. Therefore commercial diving work is very important for tidal current generator. Also, Jangjuk channel is vary famous as proper area to generate tidal current energy. Nevertheless, no one is studied about characteristics of commercial diving works with installation of tidal current generator. The purpose of this study is to introduce commercial diving with work types and investigate critical limits of diving working under the conditions, which are working only to minutes at slack tide during the neap tide. As the results, work types are five as like mooring installation, OMAS(Offshore Maintenance Access System), support structure installation, cable and turbine installation. Here, the original construction period is expected about 4 months, but the construction take 18 months to complete. The cause of extends construction period is insufficiency of researching tidal current conditions at the site and ignorance of slack tide which need to secure diving working time. Total diving working times are 110th during 18 months, the highest percentage of diving times is turbine installation about 43.6 %, and cable, mooring installation and support structure construction are 27.3 %, 15.5 %, 13.6 %, respectively. On the basis of this study, estimation of times of commercial diving is possible with work types of tidal current power, and has a significance as basic data to determining construction period.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.21 no.1
• /
• pp.44-47
• /
• 2016

Real-time PCR was applied to early warning of red tide. For early warning of red tide at $10cells\;mL^{-1}$, Cochlodinium polykrikoides specific real-time PCR was used as a complement of microscopy that has a lower detection sensitivity. C. polykrikoides appeared extensively in Tongyeong, Namhae waters at low densities in the end of June, and early warning of C. polyrkrikoides blooms was issued on 2 August 2015.

• Journal of Plant Biology
• /
• v.18 no.3
• /
• pp.129-134
• /
• 1975

It was studied of relation between biomass of reed communities (Phragmitis communis) and several environmental factors concerned with such as chlor ine, pH, humus content in soil and depth of seawater submerged. Two sites where were the different geographical conditions were set up. One site had two plots: H plot, at theshallows of seawater, was not submerged except at full tide or at heavy rainfall, and M plot, at medium depth of seawater, submerged at every common tide at inside of a bank along the west seashore of Mu-An-peninsula. The other site also two plots: M' plot, at medium depth, submerged about 10 hours at each tide, and L plot, at deep seawater submerged every tims at tide at the outside of a bank along the eastside estuary of Youngsan river. Maximum standing crop of the reed community was shown on 25th of June: biomass at H M, M' and L plot were respectively 4.65, 3.60, 0.98, and 0.67 kg dry weight per $m^2$. Density of individual at H, M, M' and L plot was 67, 78, 244 and 333 plants per $m^2$. Net production of the terrestrial parts of rred community on the outside of the bank were lesser as much as a sixth than that on inside, but the density of the plant on outside of the bank was higher as much 4 or 5 times than that on inside. It was assumed that the growth of reed plant was inhibited by high chlorine, high pH, less humus in soil and submergence of seawater for long period.

• Journal of Environmental Impact Assessment
• /
• v.10 no.1
• /
• pp.1-8
• /
• 2001

Detection of red tides by satellite remote sensing can be done either by detecting enhanced level of chlorophyll pigment or by detecting changes in the spectral composition of pixels. Using chlorophyll concentration, however, is not effective currently due to the facts: 1) Chlorophyll-a is a universal pigment of phytoplankton, and 2) no accurate algorithm for chlorophyll in case 2 water is available yet. Here, red band algorithm, classification and PCA (Principal Component Analysis) techniques were applied for detecting patches of Cochlodinium polykrikoides red tides which occurred in Korean waters in 1995. This dinoflagellate species appears dark red due to the characteristic pigments absorbing lights in the blue and green wavelength most effectively. In the satellite image, the brightness of red tide pixels in all the three visible bands were low making the detection difficult. Red band algorithm is not good for detecting the red tide because of reflectance of suspended sediments. For supervised classification, selecting training area was difficult, while unsupervised classification was not effective in delineating the patches from surrounding pixels. On the other hand, PCA gave a good qualitative discrimination on the distribution compared with actual observation.

• Journal of the Korean Institute of Navigation
• /
• v.9 no.1
• /
• pp.41-81
• /
• 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.

• Journal of Environmental Impact Assessment
• /
• v.16 no.6
• /
• pp.421-432
• /
• 2007

To investigate temporal and spatial variations of hydrodynamics and environmental conditions in Gyeonggi Bay, including Han River estuary, numerical experiments were performed using 3-dimensional fine grid numerical ocean model. The model successfully reproduced the physical phenomena already known in Gyeonggi Bay where tide and fresh water discharge are dominant forcings. The calculated harmonic constants of tide and tidal current agreed well with those of observations at nine tide stations and two tidal current stations. Tidal asymmetries along the Yeomha Waterway, mainly caused by non-linear effect, were well reproduced and agreed well with observations. Time series of salinity at four stations(A, B, C and D) and horizontal distributions of monthly averaged salinity show that Gyodong and Seokmo Waterways play an important role in fresh water discharge into the Gyeonggi Bay rather than Yeomha Waterway.

• Journal of Astronomy and Space Sciences
• /
• v.10 no.2
• /
• pp.189-196
• /
• 1993

Satellite laser ranging observation of LAGEOS II has been performed using the SLR System at Sheshan Laser Ranging Station, Shanghai Observatory. And we obtained 1,838 observational points. The observed range data is corrected by means of system delay correction using ground target observation, atmospheric refraction delay correction, offset correction, general relativistic correction and tide correction including solid tide, polar tide and ocean tide. As a result, the determined range delay mean value is 19.12m and the mean internal accuracy by means of polynomial fitting and least square method is $\pm$7cm. Corrected observational points are 1,340 and noise ratio to total observational points is 27.1%.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2005.09b
• /
• pp.1303-1304
• /
• 2005

The sea water and the soil of surface zone in lagoon have many physical relations between each other by both physical phenomena such as tidal motion and wave action, and activity of a creature which lives in soil zone. The soil zone has an activity of filtering the sea water at lowering tide and also the organic materials in sea water are supplied into the soil. And small creatures such as small crab eat organic materials. Usually the surface zone of lagoon becomes under the sea water in two times of a day and also is coming in two times under the sunshine and it becomes dries up conditions. Authors made the field observation at Sanbannse lagoon in Tokyo bay in several times between 2002 to 2004. The observation has been done in a half period of tide in October and November 2002 and also full tide observation is made in July 2, 2003 in summer and November 26, 2003 in autumn. In 2004, three times observations of full tide has been made in three times as June 22, July 20 and December 14. This report is the summary of results on these observations focusing on the soil surface zone and sea water at under ground and wave breaking zone.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.3
• /
• pp.121-132
• /
• 1987

The estuarine tide becomes strongly distorted as it propagates into upstream reach of tidal river system common to the west and south coasts of Korea. This distortion can be represented by friction, non-linear advection, interaction with channel geometry and freshwater discharge. In the present paper, the effect of an increased river discharge on tide progressing into the Keum River is evaluated quantitatively by one-dimensional hydrodynamic model. The computed relation between the prevailing discharges and the tide reaching the upper reaches of the river, both its range and its timing has shown that there are good agreement with theoretical inferences of Godin(1985).