• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.29 no.1
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• pp.165-171
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• 2005

When typhoon approaches, ship normally drops her anchor at proper anchorage for sheltering. If an anchoring ship is under the influence of typhoon, she can keep her position when the external force and counter force is balanced. Where, external force is induced by wind, wave and tidal currents while counter force is induced by holding power of anchor/chain and thrust force of main engine. In this study, authors presented a method to analyze theoretically the limit of external force for the ship to keep her position without being dragged and, to check the validity of method, applied this to the ship which had been anchored in Jinhae Bay when the typhoon MAEMI passed on September 2003.

• Atmosphere
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• v.20 no.3
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• pp.287-306
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• 2010

An ensemble Kalman filter (EnKF) with Weather Research and Forecasting (WRF) Model is applied for Typhoon Wukong (200610) to investigate the performance of ensemble forecasts depending on experimental configurations of the EnKF. In addition, the ensemble sensitivity analysis is applied to the forecast and analysis ensembles generated in EnKF, to investigate the possibility of using the ensemble sensitivity analysis as the adaptive observation guidance. Various experimental configurations are tested by changing model error, ensemble size, assimilation time window, covariance relaxation, and covariance localization in EnKF. First of all, experiments using different physical parameterization scheme for each ensemble member show less root mean square error compared to those using single physics for all the forecast ensemble members, which implies that considering the model error is beneficial to get better forecasts. A larger number of ensembles are also beneficial than a smaller number of ensembles. For the assimilation time window, the experiment using less frequent window shows better results than that using more frequent window, which is associated with the availability of observational data in this study. Therefore, incorporating model error, larger ensemble size, and less frequent assimilation window into the EnKF is beneficial to get better prediction of Typhoon Wukong (200610). The covariance relaxation and localization are relatively less beneficial to the forecasts compared to those factors mentioned above. The ensemble sensitivity analysis shows that the sensitive regions for adaptive observations can be determined by the sensitivity of the forecast measure of interest to the initial ensembles. In addition, the sensitivities calculated by the ensemble sensitivity analysis can be explained by dynamical relationships established among wind, temperature, and pressure.

• Journal of Navigation and Port Research
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• v.29 no.5 s.101
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• pp.357-363
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• 2005

When typhoon approaches, ship normally drops her anchor at proper anchorage for sheltering. If an anchored ship is under the influence of typhoon, she can keep her position when the external force and counter force is balanced. Where, external force is induced by wind, wave and tidal currents while counter force is induced by holding power of anchor/chain and thrust force of main engine. In this study, authors presented a method to analyze theoretically the limit of external force for the ship to keep her position without being dragged and, to check the validity of the method, applied this to the ship which had been anchored in Jinhae Bay when the typhoon MAEMI passed on September 2003.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.2
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• pp.69-83
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• 2018

The South China Sea (SCS) is a typical marginal sea characterized with the deep basin, shelf break, shallow shelf, many straits, and complex bathymetry. This study investigated the tidal characteristics and propagation, and reproduced typhoon-induced storm surge in this region using the regional real-time tide-surge model, which was based on the unstructured grid, resolving in detail the region of interest and forced by tide at the open boundary and by wind and air pressure at the surface. Typhoon Haiyan, which occurred in 2013 and caused great damage in the Philippines, was chosen as a case study to simulate typhoon's impact. Amplitudes and phases of four major constituents were reproduced reasonably in general, and the tidal distributions of four constituents were similar to the previous studies. The modelled tide seemed to be within the acceptable levels, considering it was difficult to reproduce the tide in this region based on the previous studies. The free oscillation experiment results described well the feature of tide that the diurnal tide is prevailing in the SCS. The tidal residual current and total energy dissipation were discussed to understand the tidal and sedimentary environments. The storm-surge caused by typhoon Haiyan was reasonably simulated using this modeling system. This study established the regional real-time barotropic tide/water level prediction system for the South China Sea including the seas around the Philippines through the validation of the model and the understanding of tidal characteristics.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.338-347
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• 2023

Jinhae Bay, characterized by frequent runaway ships and strong winds during typhoon attacks, poses a high risk of maritime accidents such as ship collisions and groundings. This study aims to determine a safe separation distance between ships in the Jinhae Bay anchorage, considering the unique environmental characteristics of the Korean sea area. Analysis revealed that an average of 100-200 ships anchor in the typhoon avoidance area in Jinhae Bay during typhoon attacks, with approximately 70% of ships experiencing anchor dragging owing to strong external forces exceeding 25 m/s wind speeds. In this study, we analyzed and presented the separation distances between ships during anchoring operations based on domestic and international design standards, separation distances between ships used as actual typhoon shelters in Jinhae Bay, and appropriate safe distances for ships drifting under strong external forces. The analysis indicated that considering the minimum criteria based on the design standards and emergency response time, a minimum safe distance of approximately 400-900 m was required. In cases where ample space was available, the separation distance was recommended to be set between 700 to 900 m. The findings of this study are anticipated to contribute to the development of guidelines for establishing safe separation distances between ships seeking refuge from typhoons in Jinhae Bay in the future.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.6
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• pp.625-633
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• 2015

In this study, a coupled probabilistic framework is developed to assess wind risk on apartment buildings by using the convolution of wind hazard and fragility functions. In this framework, typhoon induced extreme wind is estimated by applying the developed Monte Carlo simulation model to the climatological data of typhoons affecting Korean peninsular from 1951 to 2013. The Monte Carlo simulation technique is also used to assess wind fragility function for 4 different damage states by comparing the probability distributions of the window system's resistance performance and wind load. Wind hazard and fragility functions are modeled by the Weibull and lognormal probability distributions based on simulated wind speeds and failure probabilities. The modeled functions are convoluted to obtain the wind risk for the different damage levels. The developed probabilistic framework clearly shows that wind risk are influenced by various important characteristics of terrain and apartment building such as location of building, exposure category, topographic condition, roof angle, height of building, etc. The risk model presented in this paper can be used as tools to predict economic loss estimation and to establish wind risk mitigation plan for the existing building inventory.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.105-111
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• 2020

We defined Jeju Wind Castle and analyzed the relationship between Hallasan-Oreum-Batdam, the main subject, for the first time. In Jeju, 1.5m high Batdam(Black Silk Road), 368 Oreums, Hallasan Mountain 1950m are all unique scenery. The verification of this paper demonstrates that Samdasoo's groundwater extraction sea level is equal to the height of Hallasan and that this problem is mathematically complete in neutral plane theory. Donnaeko(700meters above sea level)-Baeknokdamdongneung-Jindallebat-Seongpanak-Gyorae(453 meters)-Witsaeoreum(1700meters) is a rain belt that hits the low-air pressure air-conditioned North Pacific humidity rising from the southeast and the high-pressure cold air of Hallasan Peak. It rains a lot because - and + are neutral plane, which adds to zero. Hallasan is called Jinsan in Jeju history. The answer is Wind Castle. The number of Oreum in Jeju is 369 including Hallasan, and Batdam, which is about 1.5m high, does not collapse even with a typhoon blowing over 50m/s. Because the wind castle's core is 1.5 meters of Batdam and it is a triangular number.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.63-70
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• 2011

Livestock buildings are rural facilities as vulnerable to natural disasters as vinyl houses. Many of livestock buildings have a roof but without side walls. The roof of such structures is easily blown away by a typhoon and this results in a heavy loss. Therefore, farmers install winch curtains on the sides to prevent damages caused by typhoons. This study purposed to examine the distribution of wind pressure coefficient among different positions of livestock shed roof according to the opening of side walls. It was found that according to the distribution of peak external pressure coefficient on the roof surface of livestock shed, the wind blowing at wind angle $0^{\circ}$ was disadvantageous to roof surface regardless of the presence of side walls. However, it was confirmed that the peak external pressure coefficient was affected by wind angle and the length of eave depending on the presence of side walls.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.479-484
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• 2007

For calculation of wave field for design of coastal and port structures, generally the wind fields from inland observation record or the predicted waves from deep water wave transformation model are being used. However, for the first case, as we should revise the wave data adopting correcting parameters depending on the distance from the coast and location, it is difficult to extract water waves from wind field. Furthermore, for the second case, because of the calculation which executed under very large grid sizes in the wide domain, the simulation(wave transformation) implied uncertainty in the near shore area and shallow region. So it's difficult to obtain exact data from the simulation. Thus, in this study the calculation of wave field on shallow water is accomplished using the observed data of typhoon 'Maemi' in the Korea Eastern South sea. Moreover, for the accuracy of the calculated wave field, we compared and studied the observed data of wave height and direction on the vicinity of the Ulsan waters. It is proved that the results of this study is more accurate than the existing method with showing ${\pm}1.3%$ difference between observed and calculated wave height distribution in Ulsan waters

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.508-520
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• 2016

In this study, variations in water temperature after the passage of typhoons in Korean waters from 2009-2015 were analyzed. Sea surface temperature (SST) images derived from satellite remote sensing data were used, and water temperature information came from real-time mooring buoys at Yangyang, Gangneung, Samcheok and Yeoungdeok, while wind data was supplied by the Korea Meteorological Administration. Differences in SST observed before and after the passage of a typhoon using the SST images were found to be affected by wind direction as well as hot and cool seasonal tendencies. Coastal water temperatures of the eastern part of the Korean peninsula, located to the right of a typhoon, as in the case of typhoons Muifa, Chanhom, Nakri and Tembin, were lowered by a coastal upwelling system from southerly winds across the water's surface at depths of 15m and 25m. In particular, typhoons Chanhom and Tembin decreased water temperatures by about $8-11^{\circ}C$ and $16^{\circ}C$, respectively. However, temperatures to the left of the typhoons were increased by a downwelling of offshore seawater with a high temperature through the mid and lower seawater layers. After the passage of the typhoons, further mixing of seawater at a higher or lower temperature due to southerly or northerly winds, according to the context, lasted for 1-2 or 4 days, respectively.