• Ocean and Polar Research
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• v.24 no.4
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• pp.325-329
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• 2002

Concentrations of Fe, Mn, Zn, Cu, Pb and Cd in two seaweed species (Sargassum miyabei and S. pallidum) from different areas in Amursky Bay near Vladivostok were determined. An assessment of heavy metal pollution in this bay was made and the results were compared with those from some localities in the world ocean.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.2
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• pp.221-231
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• 2008

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.281-281
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• 2017

• Journal of the Society of Naval Architects of Korea
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• v.49 no.3
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• pp.273-279
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• 2012

The concept of the Mobile Harbor had been made recently as a kind of feeder vehicle to transfer a certain amount of container boxes (i.e. 250 TEU at a time) from main ocean container vessels over 5,000 TEU capacity to the container terminal on land. In a harbor a short distance apart from the land, the container loading/unloading operation has to be performed on the main deck of the Mobile Harbor using the container cranes in the state of side-by-side mooring with protection of fenders and robot arms in the gap. Even under the ocean condition of the sea state class 2 or 3, the operation has to be confirmed to be safely performed. In this situation, the floating bodies considering the multiple-body interaction effect also has to be examined whether they might behave safely or not. Especially, this study focuses on the dynamic behavior of the Mobile harbor when a container box is hanged on the crane and the impact load due to the slewing motion is imposed in a certain sea state. The motion response should be controlled within the motion level to assure the safe operation.

• Journal of the Society of Naval Architects of Korea
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• v.40 no.5
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• pp.43-52
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• 2003

Two methods which estimate manoeuvring derivatives in the model of hydrodynamic force and moment acting on a manoeuvring ship using sea trial data were compared. One is the widely used parameter estimation method by using the Extended Kalman Filter (EKF), which estimates state variables of linearized state space model at every instant after dealing with the coefficients as the augmented state variables. The other one is the Estimation-Before-Modeling (EBM) technique, so called the two-step method. In the first step, hydrodynamic force of which dynamic model is assumed the third-order Gauss-Markov process is estimated along with motion variables by the EKF and the modified Bryson-Frazier smoother. Then, in the next step, manoeuvring derivatives are identified through the regression analysis. If the exact structure of hydrodynamic force could be known, which was an ideal case, the EKF method would be regarded as being more superior compared to the EBM technique. However the EBM technique was more robust than the EKF method from a realistic point of view where the assumed model structure was slightly different from the real one.

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.62.1-62.1
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• 2011

The wind can be stronger and steadier further from shore, but water depth is also deeper. Then bottom-mounted towers are not feasible, and floating turbines are more competitive. There are additional motions in an offshore floating wind turbine, which results in a more complex aerodynamics operating environment for the turbine rotor. Many aerodynamic analysis methods rely on blade element momentum theory to investigate aerodynamic load, which are not valid in vortex ring state that occurs in floating wind turbine operations. So, vortex lattice method, which is more physical, was used in this analysis. Floating platform's prescribed positions were calculated in the time domain by using floating system RAO and waves that are simulated using JONSWAP spectrum. The average value of in-plane aerodynamic force increase, but the value of out-of-plane force decrease. The maximum variation aerodynamic force abruptly increases in severe sea state. Especially, as the pitch motion of the barge platform is large, this motion should be avoided to decrease the aerodynamic load variation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.784-789
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• 2015

It was carried out a review of operating limit analysis for small high-speed boat by author. In general, a review of ship's seakeeping performance is performed in the step of ship design, but this study was carried out in the state of completion of boat. Motion performance of Pitch, Vertical and Lateral acceleration and Slamming were satisfied in some encounter angle but deck wetness was not satisfied in all it does the analysis. As a result, sea state rather than the speed and encounter angle of vessel have a greater effect on the seakeeping performance of target vessel. It seems to be due to the size of the target ship.

• Strategy21
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• s.30
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• pp.31-62
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• 2012

It is a commons sense that the Republic of Korea is a maritime state that depends its survival on International Trade and International Economy. Korea was a peninsula and do it can be both maritime and continental state by its choice. However, after the national division in 1945, South Korea had became a virtual island and pursue a maritime way for national development in the past 60 plus years. Now, South Korea is becoming a world's 12 th largest major trading and maritime state. South Korea has far more ships per capita than any other nations in the world and its economy is heavily depend upon the imports and exports with other nations in the world that pass through the oceans. Therefore, the Koreans regard the security of the sea lanes of communication as vital to the survival of the nation. The SLOC is the life line for Republic of Korea. Since the early 1990s, immediately after the Cold War was over, South Koreans began to recognize the importance of Sea Routes and thus began to build a navy that can handle with the new problems of the post Cold War era. However, the maritime security environments of the Republic of Korea today is shaky and dangerous. Almost every water near the Korean peninsula, some kind of international confrontations are going on. Territorial disputes on Dok do, Senkaku, Scarbrough, Shisha, Nansha and Eodo between and among Korea, Japan, China, Taiwan, Phillipines, Indonesia and Vietnam are the examples. In this essay, the author argues that the S. Korean efforts and capabilities to deal with these challenges are not enough and exhorts more efforts and more powerful navy for the Korean people.

• The Korean Journal of Quaternary Research
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• v.32 no.1_2
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• pp.30-40
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• 2018

In response to the increase in anthropogenic greenhouse gases, the Arctic temperature is increasing rapidly by 2-3 times other regions. This larger Arctic warming than lower latitudes is called 'Arctic Amplification'(Overland et al., 2017; Goose et al., 2018). Associated with the Arctic Amplification, the Arctic sea ice is declining rapidly and Greenland ice sheet is melting rapidly, especially around the coastal margins (State of Climate, 2018). However, Antarctic climate change appears to be different from the Arctic. In the western part of Antarctica, surface temperature is rising rapidly with large sea and land ice melting, but in the eastern part, there is little temperature change with slight increase in sea ice extent. The contrasting east-west temperature response is illustrated by the deepening of the Amundsen Sea Low whose upstream brings warm maritime air to the Antarctic peninsula and Amundsen-Bellingshausen Seas, but downstream air provides cold air to the Ross Sea, increasing sea ice. Besides, the increase in Southern Annular Mode (SAM) phase due to stratospheric ozone reduction enhances westerly winds, pushing sea ice northward by Ekman divergence and cooling east Antarctica. In this study, we review the recent Antarctic climate change and its possible causes.

• Ocean Systems Engineering
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• v.3 no.3
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• pp.167-180
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• 2013

Hydrodynamic characteristics of a bluff cylinder oscillating along transverse direction in steady flow were experimentally investigated at Reynolds number of $2{\times}10^5$. The effects of non-dimensional frequency, oscillating amplitude and Reynolds number on drag force, lift force and phase angle are studied. Vortex shedding mechanics is applied to explain the experimental results. The results show that explicit similarities exist for hydrodynamic characteristics of an oscillating cylinder in high and low Reynolds number within subcritical regime. Consequently, it is reasonable to utilize the test data at low Reynolds number to predict vortex induced vibration of risers in real sea state when the Reynolds numbers are in the same regime.