• 한국해양학회지
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• v.11 no.2
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• pp.51-56
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• 1976

A statistcal investigation was made on the seiches at Pohang harbor, east of Korea, based on the data of observations for the year 1973 and 1974. Pohang harbor has a most remarkable seiches comparing to the major harbors in Korea. The frequently observed conspicuos seiches at the harbor have a period of 20 to 24 minutes mostly and 60 to 84 minutes in the next place. Maximum height of seiches were 50cm in 1973 and 60cm in 1974, respectively, which were occured at the expansions of cold-dry continental high pressure and on the following day of passages of lowest pressurs. Minus tides at Pohang were occured more frequently than that of seiches and the minus tides falled more greatly at the time of seiches.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.3
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• pp.201-208
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• 2002

The characteristics of suspended sediment transport are analyzed at the estuaries which show significant shallow water tides, following the previous research for bottom sediment transport at the same estuaries. Several theories which are related with the formation and transition of turbidity maximum are reconfirmed by the numerical experiments. The experiments suggest the necessity of modeling the shallow water tide as a boundary condition, as was also suggested for the bed sediment transport at the previous research. Both the differences of transport characteristics between bed and suspended sediment and the differences between flood/ebb dominances and high/low water dominances are also examined at the Keum River and Youngsan River estuaries. In addition, the transport of bed and suspended sediments are found to have the opposite directions at the Youngsan River estuary which has extensive tidal flat, and thus shows pronounced ebb dominance, which is considered to be a main reason of keeping present bathymetry.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2601-2610
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• 2013

The main limiting factors of Precise Point Positioning(PPP) accuracy are errors in broadcast satellite orbits, clock errors, and the others, which are receiver-dependent errors(ionospheric, tropospheric refraction, multipath, and tides, etc.). Therefore, to facilitate high precision PPP, precise orbits/clocks corrections, the receiver-dependent errors corrections have to apply to multi frequency GNSS measurements for an ionosphere free combination and integer ambiguity resolution in real-time. Currently, there are many Analysis Centers, which offer the precise corrections stream computed in real-time using the global or regional GNSS tracking network. The goles of this research considered performances of the real-time static PPP with using RTCM corrections from NTRIP casters. For this, the corrections streams of Analysis Centers received via NTRIP does apply to GNSS data of check points individually, as well as jointly, in accordance with various session lengths. After that, have compared the PPP results from the corrections streams with each other, and with Standard Point Positioning(SPP) results.

• Journal of Astronomy and Space Sciences
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• v.31 no.1
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• pp.41-50
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• 2014

The Earth is not perfectly spherical and its rotational axis is not fixed in space, and these geophysical and kinematic irregularities work as dominant perturbations in satellite orbit propagation. The International Earth Rotation Service (IERS) provides the Conventions as guidelines for using the Earth's model and the reference time and coordinate systems defined by the International Astronomical Union (IAU). These guidelines are directly applied to model orbital dynamics of Earth satellites. In the present work, the effects of the latest conventions released in 2010 on orbit propagation are investigated by comparison with cases of applying the previous guidelines, IERS Conventions (2003). All seven major updates are tested, i.e., for the models of the precession/nutation, the geopotential, the ocean tides, the ocean pole tides, the free core nutation, the polar motion, and the solar system ephemeris. The resultant position differences for one week of orbit propagation range from tens of meters for the geopotential model change from EGM96 to EGM2008 to a few mm for the precession/nutation model change from IAU2000 to IAU2006. The along-track differences vary secularly while the cross-track components show periodic variation. However, the radial-track position differences are very small compared with the other components in all cases. These phenomena reflect the variation of the ascending node and the argument of latitude. The reason is that the changed models tested in the current study can be regarded as small fluctuations of the geopotential model from the point of view of orbital dynamics. The ascending node and the argument of latitude are more sensitive to the geopotential than the other elements. This study contributes to understanding of the relation between the Earth's geophysical properties and orbital motion of satellites as well as satellite-based observations.

• Journal of Environmental Science International
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• v.26 no.3
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• pp.325-334
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• 2017

To understand the changes in physical parameters and phytoplankton size structure caused by tides, a fixed station in the Youngsan River estuary was monitored at 2-h intervals, on April 28, 2012 and August 12, 2012. No clear relationship was observed between the temperature and salinity changes and tidal levels in April. However, in August, temperature decreased during the ebb tide and increased during the flood tide, while salinity showed the opposite trend. In addition, there was no specific change in the phytoplankton biomass corresponding to tidal levels in April. In August, the total chlorophyll a and the biomass of net phytoplankton (>$20{\mu}m$) increased almost 20 times during the ebb tide and decreased during the flood tide. The biomass of nanophytoplankton (<$20{\mu}m$) showed a similar variation in response to tidal level changes. In April, the relationship between percent contributions of phytoplankton size structure and tidal levels was not clear. In August, the net phytoplankton was dominant in the early stage and nanophytoplankton was dominant in the later stage, while contribution of nanophytoplankton and net phytoplankton increased at high tide and low tide, respectively. Therefore, in April, other factors such as freshwater discharge were more important than the tide, whereas in August, when no freshwater discharge was recorded, the changes in semidiurnal tides influenced the physical parameters and phytoplankton dynamics. These results could contribute to the understanding of phytoplankton dynamics in the Youngsan River estuary.

• Journal of Environmental Science International
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• v.21 no.9
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• pp.1079-1085
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• 2012

Ground seawater quality was investigated, and the algal growth potential (AGP) tests were performed along the Tongyeong coast to examine the inflow of materials, which is needed for the red tide species Cochlodinium polykrikoides to grow. The study was conducted to determine the mechanism for C. polykrikoidesred tides. Water temperature, salinity, pH, and dissolved oxygen (DO) ranged from 16.05 to $20.74^{\circ}C$, 18.20 to 32.11 psu, 6.00 to 7.61, and 3.41 to 7.91 mg/L (41.4-96.1%), respectively. No seasonal variation was observed in water temperature. The salinity, pH, and DO saturations at most stations were lower than those of coastal seawater at Tongyeong. The ${NH_4}^+$-N, ${NO_{2+3}}^-$-N, ${PO_4}^{3-}$-P concentrations ranged from 0.43 to 16.00 ${\mu}M$, 1.50 to 132.38 ${\mu}M$, and 1.30 to 6.29 ${\mu}M$, respectively; the values at some stations were much higher than observed in Tongyeong coast seawater. Using seawater from station B, C. polykrikoides grew consistently, with a high growth rate, similar to the red tide in nature. This seawater appeared to contain materials needed by C. polykrikoides to grow. Therefore, C. polykrikoides red tides seem to occur wherever the ground sea water contains materials that are needed for its growth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.5
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• pp.414-422
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• 2012

This study evaluated the effect of the inland pollution sources on the bacteriological water quality in Narodo area after rainfall events. Following 16 mm of rainfall, the water discharged from Dohwa Stream and contaminants from Balpo village had a very limited effect on bacteriological water quality in adjacent area and the affected area did not extend to the designated area. In comparion, after 33 mm of rainfall, the density of fecal coliforms at stations located in the mouth of Dohwa stream and the discharg point of contamination sources located in Balpo village were lower than after 16 mm of rainfall. These results were obtained during an extreme high tide near the coast the contaminants discharged from Dohwa stream and Balpo village. Therefore, it is necessary to conduct a detailed survey to examine the dffects of tides on the diffusion characteristics of the contaminants discharged from Dohwa stream and Balpo village in order to manage of Narodo area efficiently.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.1
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• pp.85-94
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• 2018

For the design of wind-power facilities, the highest and lowest astronomical tides (HAT and LAT, respectively) are needed for the tidal-water levels regarding international designs; however, the approximate highest high water and approximate lowest low water AHHW and ALLW, respectively, have been used in Korea. The HAT and LAT in the wind-farm test-bed sea should be estimated to satisfy the international standard. In this study, the HAT and LAT are therefore estimated using the hourly tidal-elevation data of the Eocheongdo, Anmado, Younggwang, Gunsan, Janghang, and Seocheon tidal-gauging stations that are located in the adjacent coastal sea. The nodal variation patterns of the major lunar components, such as $M_2$, $O_1$, and $K_1$ are analyzed to check the expected long-term lunar cycle, i.e., 18.61 year's nodal-variation patterns. The temporal amplitude variations of the $M_2$, $O_1$, and $K_1$ clearly show the 18.61-years periodic patterns in the case of the no-nodal correction condition. In addition, the suggested HAT and LAT elevations, estimated as the upper and lower confidence limits of the yearly HAT and LAT elevations, are 50 cm greater than the AHHW and 40 cm lower than the ALLW, respectively.

• Journal of Korean Library and Information Science Society
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• v.28
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• pp.61-91
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• 1998

In contemporary education, a school library is considered and valued as a vital and integral component of a school's instructional program. Especially, school library materials should contribute to execution of school curriculums through wide provision of resources. The results of the study are as follows. 1. The term 'library materials' should be changed into 'library resources' with a broad meaning. And, the scope of school library materials should include printed materials, audio-visual materials, electronic materials, associated equipment and other library resources. 2. It is desirable that the minimal standards of total collection is 5 books and 3 AV for a student in elementary schools, 7 books and 5 AV for a student in middle schools, 10 books and 7 AV for a student in high schools. 3. Annual growth is 0.5 for a student in elementary schools, 1 for a student in middle schools and 1.5 copy for a student in high schools. And, the number of minimal serials is 20 titles in elementary schools, 30 titles in middle schools and 50 tides in high schools. 4. Besides, basic collection, with the advances of technology, the school library collection should include new formats and delivery systems such as CD, video discs, videotex, computer software, satellite transmission etc. 5. The recommendable annual ratio of withdrawl is 3 to 5% for update and functional materials.

• Journal of Ecology and Environment
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• v.31 no.3
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• pp.201-206
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• 2008

This study was conducted to determine clutch size and habitat usage of Kentish plovers (Charadrius alexandrinus) breeding on Sinja-do lslet in the Nakdong Estuary from 22 April to 12 July in 1995 and from 21 April to 20 June in 1996. The Kentish plover preferred grasslands and damp sands to dry dunes as nesting sites. The difference in hatching success among these microhabitats was attributed to high tides, which washed away many nests on damp sands, and strong winds, which frequently shifted the sand to bury eggs on dry dunes. The main mortality factor in grasslands was predation by magpies Pica pica. Each clutch contained one to four eggs, with a mode of three eggs. Hatching success was highest in two-egg clutches and lowest in one- and four-egg clutches. The mean interval for egg laying was 1.8 days between the first and second eggs and 2.1 days between the second and third eggs. The average incubation period was about 24.2 days.