• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.86-94
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• 2011

This paper compares frequency domain and time domain predictions from the ShipMo3D ship motion library with observed motions from model tests and sea trials. ShipMo3D evaluates hull radiation and diffraction forces using the frequency domain Green function for zero forward speed, which is a suitable approach for ships travelling at moderate speed (e.g., Froude numbers up to 0.4). Numerical predictions give generally good agreement with experiments. Frequency domain and linear time domain predictions are almost identical. Evaluation of nonlinear buoyancy and incident wave forces using the instantaneous wetted hull surface gives no improvement in numerical predictions. Consistent prediction of roll motions remains a challenge for seakeeping codes due to the associated viscous effects.

• Atmosphere
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• v.22 no.4
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• pp.483-488
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• 2012

The monsoon front lies on East Asian region, but it gradually propagates to the north during the boreal summer. The equivalent potential temperature (EPT) reveals the thermodynamical features of air masses and monsoon front. Therefore, this study considered the thermodynamical EPT and dynamical wind fields to clarify the peculiarity of East Asian summer monsoon (EASM) variations in June and July, respectively. Western North Pacific subtropical high (WNPSH) and Okhotsk sea high (OSH) both play the crucial role to interannual variations of EASM frontal activity and amount of rainfall. The OSH is important in June, but the WNPSH is key factor in July. Furthermore, the OSH (June) is affected by North Atlantic tripolar sea surface temperature (SST) pattern and WNPSH (July) is influenced by North Indian Ocean SST warming.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1359-1361
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• 2003

A set of microwave remote sensing data collected with the newly developed UMass Imaging Wind and Rain Airborne Profiler (IWRAP) during the 2002 Atlantic Hurricane Season was analyzed to further our understanding of the effect of precipitation on scatterometer wind vector retrieval. Coincident surface wind speed and precipitation measurements were provided by the UMass Simultaneous Frequency Microwave Radiometer (SFMR). The differences between the wind estimations from IWRAP and SFMR under precipitation conditions of 0-100mm/hr and wind speed of 0-60m/s was calculated, from which the effect of precipitation on the wind vector retrieval using scatterometry is analyzed qualitatively.

• Proceedings of the Korea Water Resources Association Conference
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• 2019.05a
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• pp.24-24
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• 2019

This study investigates variations in the Western Pacific Subtropical High (WPSH) and its impact on South Korean precipitation in late summer during the period between 1958 and 2017. Composite analysis reveals that precipitation occurrence is directly linked to the displacement of the WPSH western ridge, a single, large-scale feature of the atmosphere in the Pacific Ocean. When WPSH ridging is located northwest (NW) of its climatological mean position, excessive precipitation is expected in late summer due to enhanced moisture transport. On the other hand, a precipitation deficit is frequently observed when the western ridge is located in the southeast (SE). Different phases of the WPSH are associated with lagged patterns of Pacific and Atlantic atmospheric and oceanic variability, introducing the potential to predict variability in the WPSH western ridge and its climate over northern East Asia by one month. Based on the identified SST patterns, a simple statistical model is developed and improvement in the ability to predict is confirmed through a cross-validation framework. Finally, the potential for further improvements in WPSH-based predictions is addressed.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.1
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• pp.37-47
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• 1977

Korea started the Atlantic tuna fishery from 1964 by means of longline, then added bait-boats in 1972. Both fisheries have given the top priority to catch yellowfin tuna(Thunnus albacares). The paper reviews available catch, effort and biological data, estimates some population parameters in order to understand the status of the Atlantic yellowfin tuna as a whole. The main findings are summarized as follows: 1. The total of 476 million hook-equivalent fishing effort was thrown to catch yellowfin tuna in 1974, among which one thired was shared by longliners. 2. The dominant age group becomes younger in both surface and longline fisheries. 3. The recent mortality coefficients were calculated as 1.5 for total mortality and 0.7 for fishing mortality. 4. The weight at recruitment was 2.7 kg in 1973 which was smaller than the regulation size(3.2kg) proposed by ICCAT. 5. The maximum sustained yield was calculated to 95-145 thousand metric tons, which was the level of recent catch. Therefore, it is apparent that the present yellowfin tuna fishery should continue to receive close attention.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.32 no.4
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• pp.340-355
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• 1996

In order to suggest the useful information of fishing ground, a data base system on 32bit personal computer was constructed and handled by using the catch data of Korean tuna long-line, catch by species, fishing time and place, fish price and etc. mainly from 1975 to 1992. The results obtained are as follows ; In the fishing ground displaying catch rate, the catch rate has reduced as time passed, and this penomenon was more evident in Indian. And yellowfin have high catch tate in the Western Pacific of low latitute region, bigeye tuna have in the Eastern. The region of high catch rate of bigeye tuna was moved from the Indian and the Atlantic to the Pacific. The patterns of catch numbers of yellowfin and bigeye tuna appeared nearly same that, having nothing to do with catch numbers in all oceans. The region of least catch was the Northwestern Pacific, the regions of most catch were the Western Indian and the Pacific of low latitute. As to simulation of fishing ground estimation, there were economical grounds in the Western Pacific of low latitute region, the Eastern Pacific of this, the Western Indian, the Eastern Indian, and the Atlantic, in order.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.4
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• pp.329-338
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• 2007

Data collected by on-board observers and from experimental surveys during 2004-2006 were analyzed to figure out the status of shark bycatch in Korean tuna longline fishery. Results obtained from 10 surveys indicated that 14, 13 and 1 species of shark were incidentally caught in Korean tuna longline fishery operated in the Pacific, Indian and Atlantic (Mediterranean) Ocean, respectively, and that shark bycatch accounted for about 29-31% of the total catch. Sharks brought aboard were processed in 3 ways; out of 1,127 sharks observed, 575 sharks (51.0%) were discarded after finning, 299 sharks (26.5%) were stored frozen after finning for future use and 253 sharks (22.4%) were released into the sea immediately after caught. The fin to body weight ratio of sharks was estimated to be about 4.7% which is similar to the guideline of 5% established by the international fisheries organizations. The underestimate of shark bycatch in Korean tuna longline fishery was significant because it was general practice that fishermen on-board did not count the discarded shark as a catch.

• Wind and Structures
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• v.13 no.1
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• pp.37-55
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• 2010

In this paper South Africa is divided into strong wind climate zones, which indicate the main sources of annual maximum wind gusts. By the analysis of wind gust data of 94 weather stations, which had continuous climate time series of 10 years or longer, six sources, or strong-wind producing mechanisms, could be identified and zoned accordingly. The two primary causes of strong wind gusts are thunderstorm activity and extratropical low pressure systems, which are associated with the passage of cold fronts over the southern African subcontinent. Over the eastern and central interior of South Africa annual maximum wind gusts are usually caused by thunderstorm gust fronts during summer, while in the western and southern interior extratropical cyclones play the most dominant role. Along the coast and adjacent interior annual extreme gusts are usually caused by extratropical cyclones. Four secondary sources of strong winds are the ridging of the quasi-stationary Atlantic and Indian Ocean high pressure systems over the subcontinent, surface troughs to the west in the interior with strong ridging from the east, convergence from the interior towards isolated low pressure systems or deep coastal low pressure systems, and deep surface troughs on the West Coast.

• ALGAE
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• v.26 no.3
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• pp.211-219
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• 2011

The genus Haraldiophyllum comprises seven species worldwide. Six of these are endemics with limited distributions, whereas the type species H. bonnemaisonii has been reported from the Atlantic Ocean. In Korea, H. bonnemaisonii has been previously recorded from the southern coast. During a red algal collection at Udo, Jeju Island, Korea, we found a potentially undescribed Haraldiophyllum species and analyzed its morphology and rbcL sequences. Herein we describe a new species, H. udoensis sp. nov., and compare our Udo specimen to similar congeners. This new species is characterized by one or several elliptical blades on a short cylindrical stipe with fibrous roots, blades that are monostromatic except at the base and on reproductive structures, a lack of network and microscopic veins, entire margins, lack of proliferations, growth through many marginal initials, and two distinct tetrasporangia layers. A phylogenetic rbcL sequence analysis demonstrated H. udoensis was distinct from the United Kingdom's H. bonnemaisonii, as well as from other species. Morphological and sequence data indicated a previous misidentification of H. udoensis as the type species H. bonnemaisonii. Based on maximum likelihood analysis, Myriogramme formed a sister clade with H. udoensis, with relatively low bootstrap support.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.396-401
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• 1995

Epoxy coated reinforcing steels (ECRs) were acquired from ten sources and coatings from each source were initially characterized in terms of defects, thickness, solvent extraction weight loss and hardness. Testing involved exposure in three aqueous solutions at elevated temperature (8$0^{\circ}C$) and in chloride-contaminated concrete slabs under outdoor exposure, It was found that the density and size of coating defects was the promary factor affecting ECR performance. The equivalent circuit analysis using electrochemical impedance spectroscopy (EIS) data indicated that the impedance response for well-performing ECR specimens showed no signs of active degradation at the interface although diffusional processes similar to those noted for poorly performing bars occurred here. Experimental results also indicated a relationship between corrosion behavior and bar source. Weight loss upon solvent extraction correlated with impedance reduction from hot water exposure. Coating defects during most of the tests, especially in high pH solutions containing chloride ions. ECRs with excessive coating defects, either initially present or ones which developed in service, performed poorly in every test category regardless of source. Forms of coating failure were extensive rusting at defects, blistering, wet adhesion loss, cathodic delamination, underfilm corrosion and coating cracks. These occurred sequentially or concurrently, depending on the condition of the ECR and nature of the environment