• Ocean and Polar Research
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• v.45 no.2
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• pp.89-102
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• 2023

Climate and environmental changes in the Arctic Ocean due to global warming have been linked to extreme climate change in mid-latitude regions, including the Korean Peninsula, requiring a better understanding of the Arctic climate system based on the paleo-analog. This review introduces three paleoenvironmental research cases using neodymium isotopes (¹⁴³Nd/¹⁴⁴Nd, ε_Nd) measured on two different fractions of marine sediments: silicate-bound 'detrital' and Fe-Mn oxide-dominated 'authigenic' fractions. In the first case, detrital ε_Nd in core HH17-1085-GC on the continental shelf off northern Svalbard was used for tracing changes in sediment provenance and associated glacier behavior over the last 16.3 ka. The second case showed the potential use of authigenic ε_Nd as a quasi-conservative water mass tracer. Three prominent ε_Nd peaks and troughs observed in core PS72/410-1 from the Mendeleev Ridge in the western Arctic Ocean over the past 76 ka suggested episodic meltwater discharge events during 51~46, 39~35 and 21~13 ka BP. The last case proposed the use of the difference between authigenic and detrital ε_Nd as a proxy for reconstructing glacier fluctuation. The idea is based on the assumption that enhanced glacial erosion during glacier advances can supply sufficient freshly-exposed rock substrate for incongruent weathering, potentially leading to greater isotopic decoupling between bedrock and dissolved weathering products as recorded in detrital and authigenic ε_Nd, respectively. Thus, it would be worthwhile to take advantage of sedimentary ε_Nd to improve our understanding of past environmental changes in polar regions.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.4
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• pp.149-157
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• 2010

Seasonal fluctuations in abundances and ingestion rates of the three major copepods, Acartia hongi, Calanus sinicus and Paracalanus parvus s. l., around the Taean Peninsula were studied along with the estimation of the grazing impacts by them on phytoplankton standing stocks. These three copepods occupied about 50% of total mesozooplankton abundances and about 70% of total copepod abundances. A. hongi dominated in winter and spring while C. sinicus showed only one peak in spring. P parvus s. l. occurred dominantly in summer and fall. The ingestion rates of these three copepods were the highest in spring, when their abundances of eggs and nauplii were more than 10 times greater. Abundances of copepodites of these copepods were also very abundant at this time of high ingestion rates. These increased ingestion rates seemed to be related with reproduction. The grazing impacts by these three copepods were about 5% of the available chlorophyll a in the water column (with the range of 0.7 to 40.5%). The highest value was found in spring.

• Journal of Navigation and Port Research
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• v.38 no.1
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• pp.59-64
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• 2014

As global warming continues, the rate of ice melting in polar regions is increasing rapidly. The interest related to north polar route is increasing among not only countries near Arctic ocean but also the other countries, In the past, the classification society rule related to a design and operation of ship operating in polar area has been primarily amended by Russia, Norway and Finland located near Artic area. However recently International Maritime Organization decided to legislate the Polar Code to ensure safety of a ship operating in Arctic and Antarctic Ocean, and it is scheduled to be completed until 2014. The present paper focuses on the survey of the current enactment trends of Polar Code and suggests the confrontational strategy in related organization.

• Korean Chemical Engineering Research
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• v.53 no.4
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• pp.524-529
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• 2015

This study was conducted to optimize the medium composition for cold-adaptive protease production of Enterobacteriaceae sp. by response surface methodology (RSM). Yeast extract, and TritonX-100 were identified as the significant factors affecting protease from one-factor-at-a-time method. RSM studies for optimizing protease production of Enterobacteriaceae sp. have been carried out for three parameters including yeast extract concentration, TritonX-100 concentration, and culture pH. These significant factors were optimized as 6.690 g/L yeast extract, 0.018 g/L Triton$^{TM}$ X-10, and pH 6.677. The experimentally obtained protease activity was 8.03 U /L, and it became 1.5-fold increase before optimization.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.35 no.3
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• pp.167-174
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• 2017

Antarctica, where ice sheet has been declined rapidly, should be monitored periodically. However, there are difficult to access for local survey or aircraft observation due to the vast and extreme environments of the polar regions. In order to overcome this problem, there have been a lot of studies by acquiring radar or laser data by satellite. It is also difficult to accurately measure the changes of the surface where is composed of snow or ice layer, and it is also difficult to product a high-resolution DEM. This study therefore aims to product DEMs of two periods using high-resolution KOMPSAT-3A stereo images, and DEM matching is implemented by the LZD(Least-squares Z-Differences) method to detect DEM changes in both periods. As a result, the proposed method could be suggested as comparing height differences of the two DEMs within 1m precision.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.7
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• pp.898-905
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• 2019

As the positive feedback between the absorption of chromophoric dissolved organic matter (CDOM) and acceleration of ice melt can impact the aquatic biota and dynamic heat budget, long-term monitoring of the CDOM variation in the polar ocean is necessary. However, the monitoring of CDOM is not easy because of harsh weather and difficult access, especially in the Antarctic Ocean. Therefore, the purpose of this study was to find a suitable long-term monitoring site for CDOM variation; we selected Maxwell Bay and Marian Cove at Sejong Base and horizontal and vertical distributions of CDOM were measured. After a 72 hr time-series measurement test of the CDOM variation at Sejong Dock and Sejong Cape in Maxwell Bay, Sejong Dock was selected, as it does not haveland discharge effects. The seasonal variation of CDOM was evident and the average CDOM concentration of Maxwell Bay was comparable with the adjacent sea. The CDOM at Sejong Dock from February to November 2010 was the highest in the fall and winter and the lowest during spring and summer. Thus, based on our one-year CDOM data, we suggest that Sejong Dock in Maxwell Bay is suitable for long-term monitoring of CDOM as an indicator of photochemical and biological environmental change and an important factor in determining the heating budget in the Antarctic Ocean.

• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1261-1272
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• 2018

It is important to measure the Arctic surface air temperature because it plays a key-role in the exchange of energy between the ocean, sea ice, and the atmosphere. Although in-situ observations provide accurate measurements of air temperature, they are spatially limited to show the distribution of Arctic surface air temperature. In this study, we proposed machine learning-based models to estimate the Arctic surface air temperature in summer based on buoy data and Advanced Microwave Scanning Radiometer 2 (AMSR2)satellite data. Two machine learning approaches-random forest (RF) and support vector machine (SVM)-were used to estimate the air temperature twice a day according to AMSR2 observation time. Both RF and SVM showed $R^2$ of 0.84-0.88 and RMSE of $1.31-1.53^{\circ}C$. The results were compared to the surface air temperature and spatial distribution of the ERA-Interim reanalysis data from the European Center for Medium-Range Weather Forecasts (ECMWF). They tended to underestimate the Barents Sea, the Kara Sea, and the Baffin Bay region where no IABP buoy observations exist. This study showed both possibility and limitations of the empirical estimation of Arctic surface temperature using AMSR2 data.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.4
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• pp.339-347
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• 2020

We carried out the U-Pb age dating of zircon from basement rocks in the southern part of the Danyang National Geopark. Two migmatitic gneisses composed of biotite±sillimanite±garnet+feldspar+quartz were dated. Leucosomes in the samples were clearly distinguished from their melanosomes. The U-Pb isotopic compositions of zircon from sillimanite- and garnet-bearing migmatitic samples were measured using a secondary ion microprobe, yielding metamorphic ages, 1870±10 Ma (2σ)와 1863±6 Ma (2σ), respectively. 1.87~1.86 Ga metamorphic ages are consistent with those of the Paleoproterozoic low-P and high-T regional metamorphism (1.87~1.85 Ga) in the Yeongnam Massif. The maximum depositional age based upon the apparent 207Pb/206Pb ages of detrital zircon in the samples was estimated as 2.06 Ga, and thus sedimentation age of the protolith of the migmatitic gneisses ranges between 2.06 and 1.87 Ga.

• The Journal of the Acoustical Society of Korea
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• v.29 no.4
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• pp.223-228
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• 2010

High-frequency bottom loss measurements for grazing angle of $82^{\circ}$ in frequency range 17-40 kHz were made in Jinhae bay in the southern part of Korea. Observations of bottom loss showed the strong variation as a function of frequency, which were compared to the predicted values using two-layered sediment reflection model. The geoacoustic parameters including sound speed, density and attenuation coefficient for the second sediment layer were predicted from the empirical relations with the mean grain size obtained from sediment core analysis. The geoacoustic parameters for the surficial sediment layer were inverted using Monte Carlo inversion algorithm. A sensitivity study for the geoacoustic parameters showed that the thickness of surficial sediment layer was most sensitive to the variation of the bottom loss.

• The Safety technology
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• no.166
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• pp.12-14
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• 2011

불과 2년 전 한적한 시골 농경지였던 충청남도 서천군 마서면 일대. 푸른 들판과 초록의 나무만 가득했던 이곳이 환경보존의 중요성을 알리는 '생태원'으로 변하고 있다. 무려 99만8,000$m^2$의 사업부지에 생태연구센터, 생태교육센터, 생태체험관, 야외생태체험공간 등이 내년 말 완공을 목표로 한창 조성되고 있는 것. 각 시설 모두가 세간의 큰 관심을 받고 있지만 그중에서도 삼성물산 건설부문이 시공 중에 있는 '국립 생태체험관'은 아직 완공 전임에도 국내를 넘어 세계적으로 유명세를 떨치고 있다. 열대관, 아열대관, 지중해관, 온대관 극지관 등 지구의 5대 생태계를 재현하는 '국립 생태체험관'은 전 세계 각지의 유명 생태관들의 모든 장점에다 국내만의 독창성을 더해 현존 최고 생태체험관의 탄생을 예고하고 있다. 때문에 시공사의 자긍심이 남다른 것은 당연한 일. 최신 친환경 공법을 바탕으로 건물의 가치를 높이는데 혼연의 힘을 다하고 있다. 특히 시공 과정에서 가장 많은 신경을 쓰는 것이 바로 '안전'이다. 후세에 환경보전과 보호의 필요성을 전하는 의미 깊은 장소이니 만큼 안전사고로 그 취지를 얼룩지게 할 수 없다는 것이 이곳 임직원의 각오. 안전으로 역사에 기록될 건축물을 만들고 있는 삼성물산 건설부문의 '국립 생태체험관' 신축현장을 찾아가 봤다.