• Ocean and Polar Research
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• v.43 no.4
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• pp.219-227
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• 2021

Sea surface height (SSH) anomalies were estimated from data recorded by four pressure-recording inverted echo sounders (PIESs) in the Mindanao Current region over a duration of 2 years from December 2017 to November 2019. The steric components of SSH anomalies were derived from round-trip acoustic travel times from the sea floor to the sea surface, whereas mass-loading components were derived from bottom pressures. Temporal variabilities in the total (steric and mass-loading) SSH anomalies and the steric component are extremely similar; this result implies that the steric component plays a major role in SSH anomalies in this region. Comparisons of the PIES-derived SSH anomalies with satellite-measured SSH anomalies reveal that the former has less temporal variability. Correlation coefficients between the total SSH anomalies and satellite-measured SSH anomalies are less than 0.85, which is lower than the correlation coefficient between the steric components and satellite-measured SSH anomalies.

• Ocean and Polar Research
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• v.34 no.2
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• pp.229-237
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• 2012

Using results from an Earth System model, we investigated change in primary production in the East China Sea, under a global warming scenario. As global warming progresses, the vertical stratification of water becomes stronger, and nutrient supply from the lower part to the upper part is reduced. Consequently, so is the primary production. In addition to the warming trend, there is strong decadal to interdecadal scale variability, and it takes a few decades before the warming trend surpasses natural variability. Thus, it would be very hard to investigate the global warming trend using data of several years' length.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.6 no.3
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• pp.298-308
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• 1994

Ocean circulation in the Northeast Pacific Ocean is simulated using a high-resolution primitive equation numerical model with realistic bottom topography. The goal is to explain better the details of observed interannual variability of the circulation in the Gulf of Alaska. Our numerical model suggests that there is no seasonal shift in the Alaska gyre and that the interannual variability. reported earlier, is most likely the result of embedded mesoscale eddies in the dynamic topography. Such eddies have been observed in hydrographic. satellite-tracked drifters and altimeter data from the Gulf of Alaska.

• Journal of Ocean Engineering and Technology
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• v.21 no.6
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• pp.1-6
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• 2007

A study on the new active circulation type oil-water separation system including buoyancy type guidance system was carried out in this paper. Newly developed oil-water separation system is composed of several oil separation steps. In the beginning of these steps, buoy type separation system would be used. Buoy type oil guiding system was developed based on the difference of density of water and oil.

• Ocean and Polar Research
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• v.42 no.2
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• pp.115-131
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• 2020

The effective range of surface current data observed by high-frequency radar (HFR) operated in the northern coastal area of Jeju Island by Korea Institute of Ocean Science and Technology was estimated and the distribution and variability of the M₂ tidal current of the Jeju Strait was analyzed. To evaluate the HFR data, the M₂ tidal current corrected from 25 hours current data observed by the Korea Hydrographic and Oceanographic Agency (KHOA) was compared with the M₂ tidal current in the Jeju Strait analyzed from the surface currents of HFR. The reliability of HFR data was confirmed by analyzing the characteristics of the tide components of these two data sets, and the effective range of HFR data was estimated through temporal and spatial analysis. The observation periods of HFR used in the analysis were from 2012 to 2014, and it was confirmed that there is a difference in the effective range of HFR data according to the observation time. During the analysis periods, the difference between the M₂ current ellipses from the data of KHOA and the HFR was greater in the eastern than in the western part of the Jeju Strait, and represented a high reliability in the western and central parts of the Jeju Strait. The tidal current of the Jeju Strait analyzed using the HFR data revealed a seasonal variability a relatively weak in summer and a strong in winter, about a 17% fluctuations between the summer and winter based on the length of the semi-major axis of tidal ellipse. Appraisals and results of regarding the characteristics and seasonal variability of the M₂ tidal current in the Jeju Strait using HFR data have not been previously reported, so the results of this study are considered meaningful.

• Asia-Pacific Journal of Atmospheric Sciences
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• v.54 no.4
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• pp.545-561
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• 2018

Over the North East Asia, extreme anomalous precipitation were observed in 2013 and 2014. During 2013 summer the precipitation was found to be higher (two standard deviation) than the climatological mean of the region; whereas during 2014, which was a borderline El Ni?o year, precipitation was found to be lower (one standard deviation). To understand the differences of these two anomalous years the Global/Regional Integrated Model system (GRIMs) has been used. The study found that low landsurface temperature and high sea-surface temperature over ocean caused a smaller land-sea contrast of surface temperature between East Asia and North West Pacific Ocean in 2014, which could have caused an eastward shift of mean monsoon circulation in that year compared to the circulation in 2013. Due to a change in the lower level circulation and wind field over East Asia the evaporation and moisture transport patterns became very different in those two years. In 2013, this study found high latent heat flux over Eastern China, which implies an increased surface evaporation over that region, and the moisture transported to the north by the mean monsoon circulation; whereas, there was no correlated transport of moisture to the North East Asia during 2014. The precipitable water over North East Asia has a stronger correlation with the latent heat flux over southern land region than that from Ocean region in the eastern side in both the years. A new approach is proposed to estimate the sub-grid scale hydrometeors from GRIMs, overestimated in the existing model.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.2
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• pp.99-108
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• 2014

One year long time-series current data were obtained at two stations (K1 and K2) located in the Usan Trough in the area north of Ulleungdo in the East Sea from September 2006. The observed data reveal enhanced seafloor flows in both stations with variabilities of about 20 days which is possibly governed by the topographic Rossby wave. After February 2007, strong flow in the upper layer in St. K1 appears throughout the mooring period and this is due to the passage of the warm eddy comparing with satellite sea surface temperature data. During this period, no significant correlation between the current in the upper layer and those in two deep layers is shown indicating the eddy does not affect flows in the deep ocean. It is also observed that the flow direction rotates clockwise with depth in both stations except for the upper of the K1. This implies that the deep flow does not parallel to the isobaths exactly and it has a downwelling velocity component. The possibility of the flow from the Japan Basin to the Ulleung Basin across the Usan Trough is not evidenced from the data.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1995.10a
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• pp.62-65
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• 1995

Understanding the flow circulation is of primary importance for studies of marine ecology and Pollution protection etc. However the circulation in coastal area is complicated with various processes and can not be considered as forced only by tides. The coastal area off South China is now playing an important role in economic development in southeast Asia with Hong Kong, Macao, Guangzhou and other cities situated in its central part (Fig. 1). (omitted)

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.3
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• pp.186-194
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• 2000

In this study, the oceanic responses to given atmospheric boundary conditions are investigated using a mesoscale ocean circulation model. The numerical experiments are divided into two parts: One is, so called, spin-up experiment and the other is reproduction experiment. The spin-up experiment simulates climatic state of ocean by integrating the ocean model with upper boundary conditions of the monthly mean atmospheric climate data. In the reproduction experiment, for the reproduction of major oceanic changes around Korean Peninsula during the period of 1980-1998 (19 years), the model has been integrated under the boundary condition of the 19year monthly mean atmosphere data. The spined-up state of ocean generated from the spin-up experiment is assigned to the initial boundary condition of the reproduction experiment. In the spin-up experiment, the model properly simulates the major features of circulation structure around Korean Peninsula; such as separation of East Korean Warm Current (EKWC), formation of the polar front, cold water band associated with the small scale eddies in the East Sea, the formation of front along west coast, and the seasonal variation of circulation pattern caused by changing upwind current in the West Sea. In the reproduction experiment, the model has shown the interannual sea surface temperature variations and a warming trend of about 0.5$^{\circ}$C during the period around Korean Peninsula, as in the case of the observation. Therefore, it is concluded that the model is capable of simulating not only the mean states but also the variabilities of ocean under the given atmosphere boundary conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.2
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• pp.210-226
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• 2013

Ever since the Arctic region has opened its mysterious passage to mankind, continuous attempts to take advantage of its fastest route across the region has been made. The Arctic region is still covered by thick ice and thus finding a feasible navigating route is essential for an economical voyage. To find the optimal route, it is necessary to establish an efficient transit model that enables us to simulate every possible route in advance. In this work, an enhanced algorithm to determine the optimal route in the Arctic region is introduced. A transit model based on the simulated sea ice and environmental data numerically modeled in the Arctic is developed. By integrating the simulated data into a transit model, further applications such as route simulation, cost estimation or hindcast can be easily performed. An interactive simulation system that determines the optimal Arctic route using the transit model is developed. The simulation of optimal routes is carried out and the validity of the results is discussed.