• Ocean and Polar Research
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• v.34 no.2
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• pp.201-218
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• 2012

The purpose of this study is to investigate climatological variations from the sea surface temperature (SST), chlorophyll-a concentration (Chl-a), and phytoplankton size class (PSC), using NOAA AVHRR, SeaWiFS, and MODIS data in the South Sea of Korea (SSK) and East China Sea (ECS). 26-year monthly SST and 13-year monthly Chl-a and PSC data, separated by whole and nine-different areas, were used to understand seasonal and inter-annual variations. SST and Chl-a clearly showed seasonal variations: higher SST and Chl-a were observed during the summer and spring, and lower values occurred during the winter and summer. The annual and monthly SST over 26 years increased by $0.2{\sim}1.0^{\circ}C$. The annual and monthly Chl-a concentration over 13 years decreased by $0.2{\sim}1.1mg/m^3$. To determine more detailed spatial and temporal variations, we used the combined data with monthly SST, Chl-a, and PSC. Between 1998 and 2010, the inter-annual trend of Chl-a decreased, with decreasing micro- and nano-size plankton, and increasing pico-size plankton. In regional analysis, the west region of the study area was spatially and temporally correlated with the area dominated by decreasing micro-size plankton; while the east region was less sensitive to coastal and land effects, and was dominated by increasing pico-size plankton. This phenomenon is better related to one or more forcing factors: the increased stratification of ocean driven by changes occurring in spatial variations of the SST caused limited contributions of nutrients and changed marine ecosystems in the study area.

• Ocean and Polar Research
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• v.43 no.1
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• pp.31-43
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• 2021

To understand the temporal variation of prokaryotic communities in a temperate coastal area, prokaryotic abundance, activity, and community composition were investigated every week for over a year at a coastal monitoring station of Yeong-do, Busan. The prokaryotic abundances fluctuated about 10 times, ranging from 2.0 to 20.1 × 10⁵ cells mL^-1 and tended to be high in spring when phytoplankton bloom occurred. The prokaryotic thymidine incorporation rates (TTI) varied in a low range between 0.2 and 11.5 pmol L^-1 h^-1 in winter. However, in summer, TTI were increased up to a range of 8.3 to 17.4 pmol L^-1 h^-1, showing an increasing pattern in summer. During the study period, Alphaproteobacteria was the most dominant class for most of the year, followed by Flavobacteria. While the seasonal variation of prokaryotic composition was not apparent at the class level, many prokaryotic species showed a distinct temporal or seasonal variation for the year. In the coastal site, prokaryotic biomass and activity did not show significant correlations with temperature and chlorophyll-a, which are well known to regulate prokaryotic growth in marine environments, suggesting that the study area may be affected by diverse sources of organic matter for their growth.

• Structural Engineering and Mechanics
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• v.4 no.3
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• pp.227-242
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• 1996

An important class of problems in the field of geotechnical engineering may be analyzed with the aid of a simple integro-differential equation. Behavior of "rigid" piles(say concrete piles), "deformable" piles(say gravel piles), pile groups, pile-raft foundations, heavily reinforced earth, flow within circular silos and down drag on cylindrical structures (for example the crusher unit of a mineral processing complex) are the type of situations that can be handled by this type of equation. The equation under consideration has the form; $$\frac{{\partial}w(r,\;z)}{{\partial}z}+f(z){\int}^z_0g({\xi})(\frac{{\partial}^2w(r,\;{\xi})}{{\partial}r^2}+\frac{1}{r}\frac{{\partial}w(r,\;{\xi})}{{\partial}r})d{\xi}+h(r,\;z)=0$$ where w(r, z) is the vertical displacement of a soil particle expressed as a function of the polar cylindrical space coordinates (r, z) and the symbols f, g and h represent soil properties and the loading conditions. The merit of the analysis is its simplicity (both in concept and in application) and the ease with which it can be expressed in a computer code. In the present paper the analysis is applied to investigate the behavior of a single rigid pile to bedrock. The emphasis, however, is placed on developing the equation, the numerical techique used in its evaluation and validation of the technique, hereafter called the ID technique, against a formal program, CRISP, which uses the FEM.

• Journal of the Society of Naval Architects of Korea
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• v.48 no.2
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• pp.171-177
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• 2011

Tensile tests were conducted at low temperatures for the steel materials which are used for outer shell of the vessels making transit through the polar regions. The selected steel materials were GL-DH32, GL-DH36 and GL-EH36. In comparison with the results at room temperature, the yield stress increases approximately by 10 to 13 percent at $-30^{\circ}C$ and by 13 to 19 percent at $-50^{\circ}C$ while the tensile strength increases about by 9 percent at $-30^{\circ}C$ and 11 to 14 percent at $-50^{\circ}C$. To obtain true stress-true strain, i.e. correct plastic hardening characteristics, Bridgman's(1952) necking correction formula was introduced taking triaxial state of stresses after onset of diffuse necking into consideration. Photographs of fractured surfaces were taken by using Scanning Electron Microscope immedately after tensile tests completed and one for GL-EH36 has been presented in this paper.

• Journal of Ocean Engineering and Technology
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• v.37 no.5
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• pp.215-224
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• 2023

While melting glaciers due to global warming have facilitated the development of polar routes, Arctic vessels require reliable anti-icing methods to prevent hull icing. Currently, the existing anti-icing method, i.e., the heating coil method, has disadvantages, such as disconnection and power inefficiency. Therefore, a carbon nanotube-based surface heating element method was developed to address these limitations. In this study, the numerical analysis of the surface heating element method was performed using ANSYS. The numerical analysis included conjugate heat transfer and computational fluid dynamics to consider the conduction solids and the effects of wind speed and temperature in cold environments. The numerical analysis method of the surface heating element method was validated by comparing the experimental results of the heating coil method with the numerical analysis results (under the -30 ℃ conditions). The surface heating element method demonstrated significantly higher efficiency, ranging from 56.65-80.17%, depending on the conditions compared to the heating coil method. Moreover, even under extreme environmental conditions (-45 ℃), the surface heating element method satisfied anti-icing requirements. The surface heating element method is more efficient and economical than the heating coil method. However, proper heat flux calculation for environmental conditions is required to prevent excessive design.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.5
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• pp.367-375
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• 2006

The chemical components, lipid class, and fatty acid composition of muscle from male and female common squid, Todarodes pacificus, were examined to evaluate the potential utilization of muscle from fin, head, arms, and tentacles, which consumers usually like less than the mantle. The mantle was found to constitute 47-49% of the total muscle and the proportion was slightly higher in females than in males. For the remaining 51-53% of the muscle, the only gender difference was that the arms of males contained approximately 3% more muscle than those of females (P<0.05). The protein content was higher in the mantle, arms, and tentacles than in the fin and head in both males and females (P<0.05), and was slightly higher in males (15.7-20.7%) than in females (15.1-19.2%). By contrast, the lipid content was slightly higher in females (1.82-2.54%) than in males (1.01-2.37%), and the fins in both males and females contained the most lipids (2.37-2.54%) of all muscle. The prominent lipid classes in the muscles were free sterol (males 81.5-91.9% vs. females 84.9-91.8% for the non-polar lipid content), phosphatidylcholine (PC, males 59.3-62.4% vs. females 49.2-57.8% for the phospholipid content) and phosphatidylethanolamine (PE, males 22.0-28.8% vs. females 25.6-33.8% for the phospholipid content). The percentage of PC was approximately 5-10% higher in males (P<0.05), especially in the fin, while that of PE was approximately 3-5% higher in female (P<0.05), especially in the head. All of the squid muscle contained 52.1-54.9% of n-3 polyunsaturated fatty acids (PUFA), such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Males contained slightly more DHA, whereas female contained more EPA. The total percentage of n-3 PUFA differed little among muscles within the same gender.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.59-73
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• 1982

Differences of lipids, especially total lipid composition, fatty acid and sterol composition of the flesh lipids between three species of cephalopods were investigated, since available researches concerning lipids in flesh tissues of the cephalopod are very limited. Extracted total lipid from the flesh tissues were fractionated by silicic acid column chromatography into three lipid classes of neutral lipids, glycolipids and phospholipids. The lipid compositions of total lipid and neutral lipids were estimated by the method of thin layer chromatography and TLC-scanner. The sterol compositions of unsaponifiable matters from total lipid were determined by using thin layer chromatography and gas-liquid chromatography. The fatty acid composition of each lipid class was also determined by gas-liquid chromatography. Total lipid contents of flesh tissues from three species of the cephalopods were 0.5 in Octopus vulgare, 0.8 in Octopus variabilis and $0.6\%$ in Loligo beka based on wet weight, the contents of total fatty acid in total lipid were 19.3, 47.8 and $38.4\%$, and the contents of unsaponifiable matters were 10.9, 18.8 and $41.1\%$, respectively. Total lipid was mainly composed of sterols and polar lipid-pigments as major components in each sample and the proportion of sterols and polar lipid-pigments to total lipid ranged from 27.0 to $35.5\%$ and 38.3 to $63.4\%$, respectively. The other lipid components of total lipid, e.g. triglycerides, free fatty acids, and carbohydrate-esterified sterols were determined as a minor components. The major component fatty acid in total lipid was palmitic acid and additionaly it chiefly consisted of the other unsaturated acids such as oleic, linoleic, octadecatetraenoic and eicosapentaenoic acid as major components of the acid. The compositions of sterol in three species of cephalopod were found to contain mainly cholesterol for its proportion to total sterols was 82.4 to $89.1\%$. However the other sterols such as 22-dehydrocholesterol and 24-methylenecholesterol were determined in addition to cholesterol as a minor components. The result of fractional composition of lipid class in total lipid was that total lipid had large .amount of polar lipid and small amount of nonpolar lipid i, e, neutral lipid in each sample, and the contents of phospholipid were higher than that of glycolipid in polar lipid. Neutral lipid was mainly composed of free sterol as major components in each sample and its proportion of free sterols to total neutral lipid was 50.0 to $70.5\%$. The other lipid components of neutral lipid showing similar in quantity, esterified sterols, free fatty acids and triglycerides were determined as a minor components. The major components fatty acid in neutral lipid were palmitic, oleic and hexadecadienoic acid. Palmitic acid was the most abundant and additionaly oleic, linoleic, octadecatetraenoic and myristic acid were the major component fatty acid in glycolipid. But, especially, glycolipid of Loligo beka contained a higher amount of arachidonic acid which also consists of major component in addition to those of acids. Palmitic acid was the most abundant and additionaly, oleic, linoleic and octadecatetraenoic acid were the major component fatty acids in phospholipid.

• Journal of the Korean Society of Food Science and Nutrition
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• v.19 no.4
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• pp.291-300
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• 1990

The lipid compositions including fatty acid sterol lipid class and the lipid component of the total lipid extracted from the flesh of some fresh water fishes I. e. mandarin cornet cat fish and Korean perch were compared. The levels of total lipid of flesh tissues from the fresh water fishes were high(7.4%) in cat fish but low(1.4-2.2%) in mandarin fish Korean perch and cornet fish. On the contrary the content of unsaponifiable matters found in total lipid was low(2.6%) in cat fish but high(6.0%-6.5%) in mandarin fish Korean perch and cornet fish. Total lipids were mainly composed of triglyceride(74.6-86.5%) as major component in each sample and the other lipid components of total lipid e. g. polar lipid free fatty acids and free sterol were the minor components, The major fatty acids in total lipid of each sample were{{{{ {C }_{16 { }:_{ }0 } }}}}(19.6-29.2%) {{{{ {C }_{16 { }:_{ }1 } }}}}(17.3-30.7%) and {{{{ {C }_{18 { }:_{ }1 } }}}}(16.8-29.2%) and additionally it chiefly consisted of {{{{ {C }_{14 { }:_{ }0 } }}}} and {{{{ {C }_{18 { }:_{ }2 } }}}} Particularly the contents of polyenoic acids in total lipid of cat fish were higher than those of the other fish samples. The level of cholesterol in total lipid was low (8.3mg/g) in cat fish but were high(36.9-59.9mg/g) in mandarin fish Korean perch and cornet fish. The contents of fractionated neutral lipid(NL) were higher than those of polar lipid(PL) in each sample. Particularly phospholipid content in PL was low(6.0%) in cat fish but were high(23.1-36.3%) in mandarin fish Korean perch and cornet fish. Neutral lipids were mainly consisted of triglyceride(84.5-93.4%) as amjor component in each sample and the other lipid components of neutral lipid e, g, free fatty acids and free wterol were exhibited as a minor components, The fatty acid compositon of neutral lipids was very resembled to total lipids. The phospholipid in mandarin cornet and cat-fish were mainly composed of phosphatidyl serine(23.1-49.8%) and phosphatidyl choline(20.8-45.3%) The relatively higher amounts of phosphatidyl serine were observed in mandarine cornet and cat-fist than in Korean perch, But phosphatidyl ethanolamine(42.3%) and phosphatidyl choline (49.9%) were the main phospholipid in Korean perch. The extraordinary high content of phos-phatidyl ethanolamine compared to other fishes was characteristics in phospholipid composition of Korean perch. The major fatty acids in phospholipid of each sample were {{{{ {C }_{16 { }:_{ }0 } }}}} (38.3-46.5%) {{{{ {C}_{18 { }:_{ }0 } }}}}(14.2-21.7) and C16:1(11.6-13.8%) and additionally it chiefly consisted of C18:2, C18:0 and C17:0 The major fatty acids in glycolipid of each sample were C16:0(28.8-40.1%) C18:1(5.4-29.9%) C18:0(5.1-28.9%) and C16:1(8.2-20.1%) and additio-nally it chiefly consisted of C14:0 and C20:1.

• Ocean and Polar Research
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• v.42 no.2
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• pp.171-178
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• 2020

R/V EARDO, commissioned in 1992, has successfully carried out ocean research campaigns in Korean jurisdictional and adjacent waters, including continental margins and coastal zones within the Korean Exclusive Economic Zone (EEZ), for 29 years. However, it will soon be reaching the end of its useful service life. A replacement for R/V EARDO is urgently needed to ensure the safety of vessel itself and its crews, and efficient ship operation and maintenance, as well as to meet modern scientific mission requirements (SMRs). Basic specifications for a replacement ship have been devised and reviewed over the past nine months. A test of the proposed hull form was also performed. The total tonnage of the proposed vessel is approximately 740 tons, and the overall length and width are 62.0 and 11.6 m, respectively. The new ship will thus be 73% larger than the current R/V EARDO; in particular, the research workspace will be 4.4 times larger. The major design priorities are the propulsion system, efficiency of radiated noise and vibration control, and the dynamic positioning system. An environmentally friendly emission system, meeting International Maritime Organization (IMO) Tier III regulations, will be installed in the third exhaust pipe. Various wet and dry lab spaces as well as 32 different scientific instruments have also been considered in the ship design.

• Ocean and Polar Research
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• v.33 no.1
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• pp.35-43
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• 2011

Blubber plays different biological roles in cetaceans, including structural support, physiological demands (thermoregulation, streamlining, buoyancy, etc.), and energy storage. As such, biochemical composition, especially lipid, in the blubber may be vertically stratified in order to effectively assist with these functions. We analysed lipid content, class and fatty acid composition in the blubber of by-catch minke whale (Balaenoptera acutorostrata; n = 11), long-beaked common dolphin (Delphinus capensis; n = 3) and Pacific white-sided dolphin (Lagenorhynchus obiquidens; n = 2) from Korean waters. Lipid content for all three species ranged from 55 to 96% of wet weight, with a dominance of triacylglycerols. Vertical stratification of blubber lipid content was different between species. For minke whale and longbeaked common dolphin, it increased from inner (near the muscle) to outer (near the skin) layer, whereas it decreased for Pacific white-sided dolphin. Thirty-one fatty acids were found in all blubber samples and vertical stratification of fatty acid composition was similar among all three species. Among grouped fatty acids, monounsaturates were the most abundant, gradually increasing from inner to outer blubber layer, whereas polyunsaturates and saturates decreased. Such vertical stratification of lipid content and composition suggests that the modification and accumulation of lipid occur in the blubber itself in order to help cetaceans with their specific physiological needs.