• Title, Summary, Keyword: Astronomical Tide

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Estimation of Extreme Tide for Risk Analysis of Marine Salvage in the Namhae (southern sea of Korea) (한국 남해의 구난환경 위험성 분석을 위한 극치 조석 산정)

  • Lee Moon-Jin
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.12 no.1
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    • pp.33-38
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    • 2006
  • In marine salvage, extreme tide heights and tidal currents are necessary to anchor an accidental ship. In order to meet this requirement, a simple scheme was developed which yields the spatial informations on the extreme tide from the distribution of approximate highest astronomical tide heights using a relationship between extreme and highest astronomical tides at the standard port. This method is the inference method based on horizontally homogeneity of tide. This scheme was applied to estimate extreme tide heights and tidal currents in the Namhae (southern sea of Korea). The highest astronomical tide heights are computed by amplitude of four major constituents (M2, S2, K1, O1 tide). The estimated extreme tide heights are ranged from 70 to 260 cm for return period 50 years and from 80 to 270cm for return period 100 years, respectively. For return period 100 years, extreme tidal currents show value of 1.55 times as strong as those of normal state.

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Analysis on the Estimation Error of the Lowest and Highest Astronomical Tides using the Wido Tidal Elevation Data (위도 검조자료를 이용한 최저-최고 천문조위 추정 오차 분석)

  • Jeong, Shin Taek;Yoon, Jong Tae;Cho, Hongyeon;Ko, Dong Hui;Kang, Keum Seok
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.2
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    • pp.101-108
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    • 2016
  • In designing of the wind power facilities, the highest and lowest astronomical tides (HAT and LAT) are needed in terms of an international design tidal water levels. The AHHW and ALLW, however, have been used as the design tidal levels in Korea. The HAT and LAT in the Wido coastal sea should be estimated to satisfy the standard because the pilot wind power facilities will be located in the adjacent Wido coastal sea. In this study, the HAT and LAT are estimated using the 31-years hourly tidal elevation data of the Wido tidal gauging station and the nodal variation patterns of the major lunar components, such as $M_2$, $O_1$, and $K_1$, are analysed 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 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, show 40 cm greater than AHHW and 35 cm lower than ALLW, respectively.

[ERRATUM] TIDAL EVOLUTION OF LUNAR ORBIT AND EARTH ROTATION

  • Na, Sung-Ho
    • Journal of The Korean Astronomical Society
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    • v.47 no.1
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    • pp.41-41
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    • 2014
  • The equivalent phase lag ${\varepsilon}_{lmpq}$ of Earth tide suggested by Lambeck have been found reasonable. Due to a mistake in his calculation, the author falsely claimed that those are too large. However, the main contents of the article are valid and not affected by this mistake.

The Regional Classification of Tidal Regime using Characteristics of Astronomical Tides, Overtides and Compound Tides in the Han River Estuary, Gyeonggi Bay (천문조, 배조 및 복합조 특성을 이용한 경기만 한강하구 구역별 조석체계 분류)

  • Yoon, Byung Il;Woo, Seung-Buhm;Kim, Jong Wook;Song, Jin Il
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.27 no.3
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    • pp.149-158
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    • 2015
  • In this study, we investigate tidal wave propagation characteristics, and classify regional tidal regime using tidal form number considered distribution of astronomical tide, overtides, and compound tides in the Han River Estuary, Gyeonggi Bay. The characteristics of the tidal wave propagation in main channels show dominance of major tidal constituents (e.g., $M_2$, $S_2$, $N_2$, $K_1$ and $O_1$) contributing to the astronomical tide however, distinct increasing of shallow water (e.g., $M_4$) and long period (e.g., $MS_f$) components toward up-estuary. Using the characteristics of tidal form number to astronomical tide, overtides, and compound tides, the regional tidal regime could be assorted into three regions. Firstly, a dominance area of astronomical tide was presented from open sea to a front of Incheon Harbor (Yeomha channel) and to north entrance of Seokmo channel. The area between south and north entrance of Yeomha channel and Ganghaw north channel classified into zone of showing strong shallow water components. It could be separated into upper estuary, upstream the Singok underwater dam, showed dominance of shallow overtides (e.g., $M_4$ and $MS_4$) water and long-term compound tides (e.g., $MS_f$) larger magnitude than astronomical tide. The shallow water components was earlier generated in lower part (south entrance) of Yeomha channel have strong bottom by effect of shallower and narrower compared with Seokmo channel. Tidal asymmetries of upper estuary cause by a development of overtides and compound tides are mainly controlled by influence of man-made structure.

TIDAL EVOLUTION OF GLOBULAR CLUSTERS: THE EFFECTS OF GALACTIC TIDAL FIELD, DIFFUSION AND BLACK HOLES

  • OH KAP SOO
    • Journal of The Korean Astronomical Society
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    • v.27 no.1
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    • pp.61-76
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    • 1994
  • We investigate the dynamical evolution of globular clusters under the diffusion, the Galactic tide, and the presence of halo black holes. We compare the results with our previous work which considers the diffusion processes and the Galactic tide. We find the followings: (1) The black holes contribute the expansion of the outer part of the cluster. (2) There is no evidence for dependence on the orbital phase of the cluster as in our previous work. (3) The models of linear and Gaussian velocity distribution for the halo black holes do not show any significant differences in all cases. (4) The perturbation of black holes reduces the number of stars in lower energy regions. (5) There is a significant number of stars with retrograde orbits beyond the cutoff radius especially in the case of diffusion and the perturbation of black holes.

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ON ASTRONOMICAL RECORDS OF DANGUN CHOSUN PERIOD

  • LA DAILE;PARK CHANGBOM
    • Journal of The Korean Astronomical Society
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    • v.26 no.2
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    • pp.135-139
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    • 1993
  • Events of eclipses as well as other major astronomical events observable in the eastern sector of Asian continent are computed and checked with astronomical records of antiquity. Particular attention was given to two types of the events recorded in remaining records of Dangun Chosun Period (DCP): (1) concentration of major planets near the constellation of Nu-Sung $(\beta\;Aries)$ and (2) a large ebb-tide. We find them most likely to have occurred in real time. i.e., when the positions of the sun, moon, and planets happen to be aligned in the most appropriate position. For solar eclipses data, however, we find among 10 solar eclipse events recorded, only 6 of them are correct up to months, implying its statistical significance is no less insignificant. We therefore conclude that the remaining history books of DCP indeed contains important astronomical records, thereby the real antiquity of the records of DCP cannot be disproved.

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Typhoon-Surge Characteristics and the Highest High Water Levels at the Western Coast (서해안의 태풍해일특성과 고극조위)

  • Kang, Ju Whan;Kim, Yang-Seon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.31 no.2
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    • pp.50-61
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    • 2019
  • The aspects of typhoon-induced surges were classified into three types at the Western coast, and their characteristics were examined. The typhoons OLGA (9907) and KOMPASU (1007) were the representative steep types. As they pass close to the coasts with fast translation velocity, the time of maximum surge is unrelated to tidal phase. However, typhoons PRAPIROON (0012) and BOLAVEN (1215) were the representative mild types, which pass at a long distance to the coasts with slow translation velocity, and were characterized by having maximum surge time is near low tide. Meanwhile, typhoons MUIFA (1109) and WINNIE (9713) can be classified into mild types, but they do not show the characteristics of the mild type. Thus they are classified into propagative type, which are propagated from the outside. Analyzing the annual highest high water level data, the highest water level ever had been recorded when the WINNIE (9713) had attacked. At that time, severe astronomical tide condition overlapped modest surge. Therefore, if severe astronomical tide encounter severe surge in the future, tremendous water level may be formed with very small probability. However, considering that most of the huge typhoons are mild type, time of maximum surge tends to occur at low tide. In case of estimating the extreme water level by a numerical simulation, it is necessary not only to apply various tide conditions and accompanying tide-modulated surge, but also to scrutinize typhoon parameters such as translation velocity and so on.

Analysis on the estimation errors of the lowest and highest astronomical tides for the southwestern 2.5 GW offshore wind farm, Korea

  • Ko, Dong Hui;Jeong, Shin Taek;Cho, Hong-Yeon;Kang, Keum-Seok
    • 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.