• Ocean and Polar Research
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• 제37권1호
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• pp.23-35
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• 2015

A 450 m-long sediment section was recovered from Hole U1359D located at the eastern levee of the Jussieau submarine channel on the Wilkes Land continental rise (East Antarctica) during IODP Expedition 318. The age model for Hole U1359D was established by paleomagnetic stratigraphy and biostratigraphy, and the ages of core-top and core-bottom were estimated to be about 5 Ma and 13 Ma, respectively. Biogenic opal content during this period varied between 3% and 60%. In the Southern Ocean, high biogenic opal content generally represents warm climate characterized by the increased light availability due to the decrease of sea-ice distribution. The surface water productivity change in terms of biogenic opal content at about 10.2 Ma in the Wilkes Land continental rise was related to the development of Northern Component Water. After about 10.2 Ma, more production of Northern Component Water in the North Atlantic caused to increase heat transport to the Southern Ocean, resulting in the enhanced diatom production. Miocene isotope events (Mi4~Mi7), which are intermittent cooling intervals during the Miocene, appeared to be correlated to the low biogenic opal contents, but further refinement was required for precise correlation. Biogenic opal content decreased abruptly during 6 Ma to 5.5 Ma, which most likely corresponds to the Messinian salinity crisis. Short-term variation of biogenic opal content was related to the extent of sea-ice distribution associated with the location of Antarctic Polar Front that was controlled by glacial-interglacial paleoclimate change, although more precise dating and correlation will be necessary. Diatom production in the Wilkes Land continental rise increased during the interglacial periods because of the reduced sea-ice distribution and the southward movement of Antarctic Polar Front.

• 한국초등과학교육학회지:초등과학교육
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• 제33권2호
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• pp.401-414
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• 2014

The purpose of this study is to investigate the elementary preservice teachers' conceptions about 'plastics' focusing on non-polar property from a National University of Education. For the study, the views about plastics, relative shapes of a water droplet on plastic or glass material, and relative shapes of water surface in the plastic or glass measuring cylinder were surveyed from the preservice teachers. And the responses were analyzed based on the patterns. The results from the study are as follows: First, most preservice teachers were well aware of the plastic products which are used in daily life. Second, the responses concerning the reason why plastics can be used commonly were divided into 2 categories with 14 sub-level groups. However relatively few preservice teachers mentioned regarding 'chemical stability' and 'conductivity', which are associated with the plastics' non-polar property. Third, it was found that 50 participants (30.1%) had 'Scientific conception (Sc)', 38 (22.9%) had 'Partial-scientific conception (Ps)', 66 (39.8%) had 'Misconception (Mc)', and 12 (7.2%) had 'No conception (Nc)' on the subject of the relative shapes of a water droplet. Fourth, the distribution patterns and the ratio of the preservice teachers' conception on the survey question 3 concerning the relative shapes of water surface were quite similar to those of the survey question 2. So it was concluded that overall understanding level of the preservice teachers was pretty low on the subjects of the relative polarities of the plastic, glass, and water as well as their interactions. Fifth, the distribution percentile of 'Sc'/'Ps'/'Mc'/'Nc' was not related with the gender but highly correlated with preservice teachers' academic field and their science subjects taken in high school. Based on the results from the study, some educational guidelines were suggested.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2009년도 학술대회 초록집
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• pp.119-123
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• 2009

지하수 수위 변동에 따른 중력 변화를 이동식 기조력 중력계(PET)를 이용하여 충청남도 금산군에 위치한 국가 지하수 관측소(금산 금산 지하수관측소)에서 측정하였다. 중력 탐사는 2008년 11월부터 2009년 9월까지 약 10개월에 걸쳐 수행되었다. 또한 중력탐사가 수행되는 기간 동안 지하수 수위변화에 대한 자료도 얻었다. 얻어진 중력 자료로부터 지하수의 수위변동에 의한 효과만을 추출해 내기 위하여, 대기압에 의한 효과, 조석 효과, ocean loading 효과, polar motion과 drift 효과를 제거하였다. 이렇게 보정된 중력 자료를 관측정에서 측정한 지하수 수위변동과 직접 비교하여 중력 신호에 대한 지하수 수위 변동의 영향을 알아보았다. 또한 6월에는 지하수 관측소에 대한 양수 작업이 있었다. 이 작업이 수행되는 동안 지하수의 수위 강화와 충전이 있었으며, 이와 연관된 중력변화도 매우 성공적으로 관측되었다. 지하수 수위변동에 의한 중력 효과의 관측은 대수층의 water mass balance와 수자원에 대한 모니터링에 있어서 아주 유용하게 이용될 것으로 보인다.

• Ocean and Polar Research
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• 제24권2호
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• pp.123-134
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• 2002

Seasonal variations of settling particles and metal fluxes were monitored at a nearshore site of Marian Cove, King Geroge Island, Antarctica from 28th February 1998 to 22nd January 2000. Near-bottom sediment traps were deployed at 30m water depth of the cove, and sampling bottles were recovered every month by SCUBA divers. Total particulate flux and metal concentrations were determined from the samples. Total particulate flux showed a distinct seasonality, high in austral summer and low in austral winter: the highest flux $(21.97g\;m^{-2}d^{-1})$ was found in February of 1999, and the lowest $(2.47g\;m^{-2}d^{-1})$ in September of 1998, when sea surface was frozen completely. Lithogenic particle flux accounted for 90% of the total flux, and showed a significantly negative correlation with the thickness of snow accumulation around the study site. It was suggested that the most of the lithogenic particles trapped in the bottles was transported by melt water stream from the surrounding land. Fluxes of Al, Fe, Ti, Mn, Zn, Cii, Co, Ni, Cr, Cd, and Pb showed similar seasonal variations with the total flux, and their averaged fluxes were 34000, 9000,960, 180, 13.8, 17.6, 3.0,2.1, 5.4, 0.02, and $1.5nmol\;m^{-2}d^{-1}$ respectively. Among the metals, Cu and Cd showed the most noticeable seasonal patterns. The Cd flux correlated positively with the fluxes of biogenic components while the Cu flux correlated with both the lithogenic and biogenic particle fluxes. The Cu flux peak in the late summer is likely related to a substantial amount of inflow of ice melt water laden with Cu-enriched lithogenic particles. On the other hands, the Cd flux peak in the early spring may be associated with the unusually early occurred phytoplankton bloom.

• Korean Chemical Engineering Research
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• 제60권1호
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• pp.169-174
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• 2022

본 연구에서는 Taxus chinensis 유래 파클리탁셀의 회수 효율을 개선하기 위하여, 물 및 헥산의 순차적 세척 공정을 개발하였다. 물 세척은 시료/물 비 1:40 (w/v)에서 10 분 동안 세척함으로써 시료에 포함되어 있는 극성불순물을 효과적으로 제거할 수 있었다. 헥산 세척은 시료/헥산 비 1:160 (w/v)에서 20 분 동안 세척함으로써 시료에 포함되어 있는 비극성 불순물을 효과적으로 제거할 수 있었다. 물과 헥산의 순차적 세척을 통하여 비교적 짧은 공정 시간(~30 분)에 파클리탁셀 순도 30% 이상을 얻을 수 있었다.

• 멤브레인
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• 제28권5호
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• pp.320-325
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• 2018

FASs (fluoroalkylsilanes)로 표면 개질한 소수성 막에 대한 부탄올/물, 이소프로판올/물 용액의 수착(sorption)량을 측정하였으며 이들 수착 특성을 Hansen 용해도 파라미터를 이용하여 해석하였다. 부탄올의 수착량이 이소프토판올보다 많았으며, 이는 부탄올의 용해도 파라미터(${\delta}_t=20.4$)와 FASs 소수성 막의 용해도 파라미터(${\delta}_t=16.9$)와의 차이가 이소프로판올 (${\delta}_t=24.6$)과의 차이보다 작기 때문인 것으로 설명할 수 있다. 극성력(${\delta}_p$) 측면에서 살펴보면, FASs 극성력(${\delta}_p=4.6$)과 부탄올의 극성력(${\delta}_p=6.3$)과의 차이가 FASs 극성력(${\delta}_p=4.6$)과 이소프로판올의 극성력(${\delta}_p=9.0$)과의 차이보다 작다. 이는 부탄올-FASs 간의 극성력 차이가 이소프로판올-FASs 간의 극성력 차이보다 작아서 부탄올-FASs 간의 상호인력이 크다는 것을 의미하며, 수착량이 크게 나타나는 결과를 설명할 수 있다. 본 실험결과로부터 막에 대한 알코올의 수착특성, 용매에 대한 용질의 용해도 등을 분석하는데 용해도 파라미터를 이용할 수 있음을 알 수 있다.

• 대한환경공학회지
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• 제35권10호
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• pp.743-748
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• 2013

본 연구의 목적은 수분이 함유된 한지의 수분을 에탄올, 메탄올, 펜탄 등과 같은 비극성물질로 치환하여 한지 여과지를 만드는데 있다. 실험은 적정 비극성물질의 선택 및 적정 건조방법 그리고 제조된 한지여과지의 물리화학적 특성을 알아보기 위하여 수행되었다. 한지 종이필터를 제조하기 위하여 한지에 함유된 수분을 치환하기 위한 최적 물질은 에탄올이었으며 적정한 건조방법은 냉동 후 진공에 의해 수분을 건조하는 냉동건조방법이었다. 냉동건조에 의해 제조된 필터의 겉보기 밀도는 0.11-0.13 g/mL 으로 자연건조방법의 절반 이었으며 공극율은 약 90%로서 다공성을 나타내었다. 전자현미경 관찰결과 자연건조 및 열건조에 의해 제조된 여과지의 섬유는 섬유끼리 매우 가깝게 밀착되어 있었으나 냉동건조에 의해 제조된 섬유는 섬유간에 간격이 이격되어 있었다. 제조된 여과지의 압력손실은 자연건조 및 열건조 여과지보다 냉동건조에 의해 제조된 한지가 매우 낮았으며 BTEX제거효율은 한지의 수분을 비극성 물질에 의해 치환한 것보다 자연건조시킨 한지가 우수하였다.

• Ocean and Polar Research
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• 제40권4호
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• pp.281-288
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• 2018

The transmission of solar light according to the distribution of chromophoric dissolved organic matter (CDOM) was measured in the Pacific Arctic Ocean. The Research Vessel Araon visited the ice-covered East Siberian and Chukchi Seas in August 2016. In the Arctic, solar [ultraviolet-A (UV-A), ultraviolet-B (UV-B), and photosynthetically active radiation (PAR)] radiation reaching the surface of the ocean is primarily protected by the distribution of sea ice. The transmission of solar light in the ocean is controlled by sea ice and dissolved organic matter, such as CDOM. The concentration of CDOM is the major factor controlling the penetration depth of UV radiation into the ocean. The relative CDOM concentration of surface sea water was higher in the East Siberian Sea than in the Chukchi Sea. Due to the distribution of CDOM, the penetration depth of solar light in the East Siberian Sea (UV-B, $9{\pm}2m$; UV-A, $13{\pm}2m$; PAR, $36{\pm}4m$) was lower than in the Chukchi Sea (UV-B, $15{\pm}3m$; UV-A, $22{\pm}3m$; PAR, $49{\pm}3m$). Accelerated global warming and the rapid decrease of sea ice in the Arctic have resulted in marine organisms being exposed to increased harmful UV radiation. With changes in sea ice covered areas and concentrations of dissolved organic matter in the Arctic Ocean, marine ecosystems that consist of a variety of species from primary producers to high-trophic-level organisms will be directly or indirectly affected by solar UV radiation.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1165-1171
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• 2010

The lyotropic mesomorphism of lamellar liquid crystalline phase was examined by observing the swelling behavior of Distearoylphosphatidylcholine(DSPC) in glycerin and panthenol without water. The lyotropic mesomorphism was examined by using DSC, XRDs and Cryo-SEM. Increase of two polar solvents under non-hydrous condition showed distinctive differences in the lyotropic mesomorphism from forming different anisotropic structures with DSPC. Glycerin did not affect to the crystalline region of lamellar phase, whereas typical swelling mesomorphism was shown in the noncrystalline region. In contrast, panthenol showed some effect on the crystalline region, but common swelling mesomorphism was found in the non-crystalline region. In this case, the isopropyl and propyl groups in panthenol were the main factor to affect to the lipophilic domain in the crystalline region of lamellar phase. Also, it was found that the formation of well-arranged lamellar structure only by introducing glycerin and panthenol as a solvent without water, was possible. These results were confirmed by examination of the swelling mesomorphism of liquid crystal membrane triggered by introducing the two polar solvents.

• Ocean and Polar Research
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• 제32권3호
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• pp.321-329
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• 2010

Photosynthetic pigments, nutrients, and hydrographic variables were examined in order to elucidate the spatio-temporal variation of water column structure and its effect on phytoplankton community structure in the western channel of the Korea Strait in fall 2006 and spring 2007. High phytoplankton biomass in the spring was associated with high salinity, implying that nutrients were not supplied by coastal waters or the Yangtze-River Diluted water (YRDW) with low salinity. Expansion of the Korea Strait Bottom Cold Water (KSBCW) and a cold eddy observed during the spring season might enhance the nutrient supply from the subsurface layer to the euphotic zone. Chemotaxonomic examination showed that diatoms accounted for 60-70% of total biomass, followed by dinoflagellates. Nutrient supply by physical phenomena such as the expansion of the KSBCW and the occurrence of a cold eddy appears to be the controlling factors of phytoplankton community composition in the Korea Strait. Further study is needed to elucidate the mechanisms by which the KSBCW is expanded, and its role in phytoplankton dynamics.