• Ocean and Polar Research
• /
• v.37 no.2
• /
• pp.141-147
• /
• 2015

Snow albedo can be decreased if there are any impurities on the snow surface other than the snow itself. Due to the decrease of snow albedo, melting rates of surface snow can increase, which is very crucial in climate change and hydrogeology in many parts of the world. Anthropogenic black carbons caused by the incomplete combustion of fossil fuel affect snow and tephra particles generated by geologic volcanic activities reduce snow albedo. In this study, we investigated isotopic compositions for snow covered by tephra particles and compared with this with clean snow. Isotopic compositions of snow with tephra statistically show more enriched than those of clean snow (p<0.02). This can be explained by the fact that snow becomes enriched in $^{18}O$ or D relative to meltwater as melting rates are increased. In addition, the slopes of the linear regression between oxygen and hydrogen for snow with tephra and clean snow are 6.7 and 8, respectively, and the latter is similar to that of the global meteoric water line of 8. Therefore, we can conclude that snow impurities control the isotopic compositions of snow, which is very crucial in the study of climate change and hydrogeology. To quantitatively explain these observations, melting experiments and numerical approaches are required.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.12 no.3
• /
• pp.191-200
• /
• 1979

For the use of antarctic krill as a fond protein source its compositional characteristics were investigated as the first part of the work includes other subjects such as processing of drill paste, concentrates, and fermented or seasoned product. In general composition of fresh frozen and preboiled frozen krill on board, the contents of crude fat and free amino nitrogen were higher in the former than in the latter which contained a high amount of ash. VBN was rather high as much as 37.6 and $26.4\;mg\%$ in both fresh frozen and preboiled krill. The pH of drill homogenates was 7.1 to 7.2 in both cases. Such a low pH might be attributed to a long term storage and temperature fluctuations during frequent transshipping. The amino acid competition of fresh frozen krill meat showed relatively high amount of glutamic acid, aspartic acid, lysine, proline, and leucine while methionine, histidine, serine, tyrosine, and phenylalanine were lower. Among the essential amino acids lysine and leucine were higher and methionine was lower. In tile composition of free amino acid proline, lysing, arginine, and alanine were higher comparatively to the contents of histidine, aspartic acid, serine, and threonine. It is noteworthy for nutritional qualification that tile essential amino acids particularly as lysine were abundant similarly to that of fishes. Heavy metal contents of krill meat 0.039 to 0.048 ppm as Hg, 0.06 to 0.11 ppm as Pb, less than 0.32 ppm as Zn, 0.008 to 0.012 ppm as Cd, 0.61 to 0.68 ppm as Fe, 0.87 to 1.37 ppm as Cu, and nondetective as Cr. A high Cu content seems to be resulted by tile blood pigment of crustacea. The ratio,1 of edible portion to non-edible portion were 37:63 in fresh frozen and 42:58 in preboiled frozen krill respectively. Release of drip after thawing was more in fresh frozen than in preboiled frozen drill marking $36\%$ and $24\%$ of both respectively.

• Journal of Species Research
• /
• v.5 no.3
• /
• pp.289-299
• /
• 2016

Extensive survey of invertebrates in Korea, led by the National Institute of Biological Resources in Incheon, continues to uncover many new and endemic species, but also elements of neighbouring faunas that were previously unknown here. Hemicyclops tanakai Itoh and Nishida, 2002 was originally described from estuarine mud-flats in Tokyo Bay, Japan. We report one male and two females from a sandy beach on Jeju Island, which represent its first record in Korea and second record ever. No morphological differences were observed between these two disjunct populations, so we expect more records of this species in Korea and Japan. Tisbe ensifer Fischer, 1860 was originally described from Madeira and later on reported from numerous other parts of the Northern Atlantic, as well as from the Indian Ocean. We report two females from a shallow littoral in Sokcho, which represents its first record in Korea and the first record in the entire Pacific Ocean. Because of morphological discrepancies reported in previous records we recognize that this species might be in reality a species complex, and we only tentatively identify our Korean specimens as T. cf. ensifer. We provide numerous light photographs of both species in addition to short descriptions, in hope that they might elucidate global problems of their zoogeography and dispersal of small marine invertebrates in general. Further samplings from Korea and other parts of the world will be necessary to test our identifications and phylogenetic relationships of Korean populations with molecular and other tools.

• Journal of the Korean earth science society
• /
• v.32 no.6
• /
• pp.586-594
• /
• 2011

Gravity Recovery and Climate Experiment (GRACE), launched in April, 2002, makes it possible to monitor Earth's mass redistribution with its time-varying gravity observation. GRACE provides monthly gravity solutions as coefficients of spherical harmonics, and thus ones need to convert the gravity spectrum to gravity grids (or mass grids) via the spherical harmonics. GRACE gravity solutions, however, include spatial alias error as well as noise, which requires to suppress in order to enhance signal to noise ratio. In this study, we present the GRACE data processing procedures and introduce some applications of time-varying gravity, which are studies of terrestrial water storage changes, Antarctic and Greenland ice melting, and sea level rise. Satellite missions such as GRACE will continue up to early 2020, and they are expected to be an essential resource to understand the global climate changes.

• Korean Journal of Environmental Biology
• /
• v.38 no.1
• /
• pp.61-70
• /
• 2020

A eukaryotic microalga was isolated from seawater in Janghang Harbor, Korea and its morphological, molecular, and physiological characteristics were investigated. Due to its simple morphology, no distinctive characters were found by morphological observation, such as light microscope or scanning/transmission electron microscopy (S/TEM). However, molecular phylogenetic evidence inferred from the concatenated small subunit (SSU) 18S rRNA and internal transcribed spacer (ITS) sequence data indicated that the isolate belonged to the newly described Micractinium singularis. Furthermore, it was clustered with Antarctic Micractinium strains and it also showed a psychrotolerant property, surviving at temperatures as low as 5℃. However, its optimal growth temperatures range from 15℃ to 25℃, indicating that this microalga is a mesophile. Additionally, gas chromatography-mass spectrometry (GC/MS) analysis showed that the isolate was rich in nutritionally important omega-3 polyunsaturated fatty acid, and high-performance liquid chromatography analysis (HPLC) revealed that the high-value antioxidant lutein was biosynthesized as an accessory pigment by this microalga, with glucose as the major monosaccharide. Therefore, in this study, a Korean marine M. singularis species was discovered, characterized, and described. It was subsequently added to the national culture collections.

• Journal of Magnetics
• /
• v.21 no.4
• /
• pp.509-515
• /
• 2016

We report on development of a ground-based bi-axial Search-Coil Magnetometer (SCM) designed to measure time-varying magnetic fields associated with magnetosphere-ionosphere coupling processes. The instrument provides two-axis magnetic field wave vector data in the Ultra Low Frequency or ULF (1 mHz to 5 Hz) range. ULF waves are well known to play an important role in energy transport and loss in geospace. The SCM will primarily be used to observe generation and propagation of the subclass of ULF waves. The analog signals produced by the search-coil magnetic sensors are amplified and filtered over a specified frequency range via electronics. Data acquisition system digitizes data at 10 samples/s rate with 16-bit resolution. Test results show that the resolution of the magnetometer reaches $0.1pT/{\sqrt{Hz}}$ at 1 Hz, and demonstrate its satisfactory performance, detecting geomagnetic pulsations. This instrument is scheduled to be installed at the Korean Antarctic station, Jang Bogo, in the austral summer 2016-2017.

• Journal of the Korean Applied Science and Technology
• /
• v.35 no.2
• /
• pp.485-491
• /
• 2018

The purpose of this study was to probe the influences of krill (Euphausia superba) meal supplementation on a dose effect relationship between fluoride levels of krill meal and serum hepatic functional enzyme activity such as alkaline phosphatase (ALP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) in rats fed experimental diets for 5 weeks. There were no significant differences in the activities of ALP, AST, ALT, and LDH in sera among krill meal diet groups (KM10, KM20, KM30). However, these groups were significantly (p<0.05) lower enzyme activities than control group (CG). The fluoride levels of sera and organ tissues (liver, brain, heart, lung, kidney) in krill meal diet groups (KM10, KM20, KM30) were significantly increased by adding krill meal in comparison with CG. The results indicate that a difficult to found toxicity to the liver from krill meal diet groups.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.36 no.5
• /
• pp.343-353
• /
• 2018

Ocean tides in Antarctica are not well constrained mostly due to the lack of tidal observations. Especially, tides underneath and around ice shelves are uncertain. InSAR (Interferometric Synthetic Aperture Radar) data has been used to observe ice shelf movements primarily caused by ocean tides. Here, we demonstrate that it is possible to estimate tidal constituents underneath the Sulzberger ice shelf, West Antarctica, solely using ERS-1/2 tandem mission DInSAR (differential InSAR) observations. In addition, the tidal constituents can be estimated in a high-resolution (~200 m) grid which is beyond any tidal model resolution. We assume that InSAR observed ocean tidal heights can be derived after correcting the InSAR data for the effect of atmospheric loading using the inverse barometric effect, solid earth tides, and ocean tide loading. The ERS (European Remote Sensing) tandem orbit configuration of a 1-day separation between SAR data takes diminishes the sensitivity to major tidal constituents including $K_1$ and $S_2$. Here, the dominant tidal constituent $O_1$ is estimated using 8 differential interferograms underneath the Sulzberger ice shelf. The resulting tidal constituent is compared with a contemporary regional tide model (CATS2008a) and a global tide model (TPXO7.1). The InSAR estimated tidal amplitude agrees well with both models with RMS (root-mean-square) differences of < 2.2 cm and the phase estimate corroborating both tide models to within $8^{\circ}$. We conclude that fine spatial scale (~200 m) Antarctic ice shelf ocean tide determination is feasible for dominant constituents using C-band ERS-1/2 tandem mission InSAR.

• Journal of Ocean Engineering and Technology
• /
• v.28 no.1
• /
• pp.28-33
• /
• 2014

The Korean icebreaking research vessel "Araon" performed four sea trials in the Arctic and Antarctic Seas. The ice properties, such as the ice thickness, floe size, ice strength, and power of the vessel were quite different in these trials. To compare the speeds of ship with the same ice strength and power, the AARC (Arker Arctic Research Center) method is used with a vessel power of 10 MW and an ice strength of 630 Pa in this paper. Based on the analysis results, the speed of the ship was 1.62 knots (0.83 m/s) with a 1.02-m ice thickness and 2.5-km floe size, 5.3 knots (2.73 m/s) with a 1.2-m ice thickness and 1.0-km floe size, and 13.8 knots (7.10 m/s) with a 1.1-m ice thickness and 200-m floe size. The analysis results showed that the ship speed and floe size have an inversely proportional relationship. Two reasonable reasons are given in this paper for the final result. One is an ice breaking phenomenon, and the other is the effect of the ice floe mass. For the breaking phenomenon, the ice breaking force is very small because the ice floe is not breaking but tearing when a ship is passing through a small ice floe. Regarding the effect of the ice floe mass, it is impossible for a ship to push and tear an ice floe if the mass of the ice floe is too large compared to the mass of the ship. The velocity of the ship decreases when the ice floe has a large mass and a large size because the ship has to break the ice floe to move forward.

• Journal of Embryo Transfer
• /
• v.31 no.4
• /
• pp.355-365
• /
• 2016

The cryopreservation of sperm has become the subject of research for successful artificial insemination technologies. Antifreeze proteins (AFPs), one of the factors necessary for effective cryopreservation, are derived from certain Antarctic organisms. These proteins decrease the freezing point of water within these organisms to below the temperature of the surrounding seawater to protect the organism from cold shock. Accordingly, a recent study found that AFPs can increase the motility and viability of spermatozoa during cryopreservation. To evaluate this relationship, we performed cryopreservation of boar sperm with AFPs produced in the Arctic yeast Leucosporidium sp. AFP expression system at four concentrations (0, 0.01, 0.1, and $1{\mu}g/ml$) and evaluated motility using computer assisted sperm analysis. DNA damage to boar spermatozoa was measured by the comet assay, and sperm membrane integrity and acrosome integrity were evaluated by flow cytometry. The results showed that motility was positively affected by the addition of AFP at each concentration except $1{\mu}g/ml$ (p<0.001). Although cryopreservation with AFP decreased the viability of the boar sperm using, the tail DNA analyses showed that there was no significant difference between the control and the addition of 0.1 or $0.01{\mu}g/ml$ AFP. In addition, the percentage of live sperm with intact acrosomes showed the least significant difference between the control and $0.1{\mu}g/ml$ AFP (p<0.05), but increased with $1{\mu}g/ml$ AFP (p<0.001). Our results indicate that the addition of AFP during boar sperm cryopreservation can improve viability and acrosome integrity after thawing.