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김부근,Dongseon Kim,Hyong Chul Shin,Dong Yup Kim 한국지질과학협의회 2007 Geosciences Journal Vol.11 No.3
Sediment-trap deployment in the central Bransfield Strait during 1999/2000 shows distinct seasonal variation of particle fluxes, in which more than 99% of total annual flux occurred during a limited time. A more positive relationship between biogenic silica and total organic carbon fluxes in the intermediate-water sediment trap demonstrates that the surface-water production (mainly diatoms) played an important role in the supply of biogenic particles during the short period. The low 15N values of particulate organic particles are attributed to high nitrate concentration in the Antarctic surface waters. The gradual increasing 15N values in the bottom-water trap from the productive to unproductive season are likely associated with a switch in source from diatom aggregates to some remains of zooplankton, supplement to the horizontal contribution of lithogenic particles presumably from nearby shallow environment. Thus, the 15N enrichment of sinking particles in the bottom-water trap during December to early February seems to be due to the laterally transported materials, assuming that the 15N values decrease with depth in the Antarctic Polar Frontal region
김부근,윤호일,Cheon Yun Kang,Junlin Zhao 한국해양과학기술원 2004 Ocean and Polar Research Vol.26 No.3
A sediment core drilled from Lake Langer on King George Island was analyzed for a variety of textural and geochemical properties along with 14C age dates. These data were combined with published records of other cores to provide a detailed history of Holocene variation of total organic carbon (TOC) contents with respect to terrestrial paleoclimate change. The lithologic contrast of the lower diamicton and upper fine-grained sediments shows the glacier activity and subsequent lake formation. Low TOC contents fluctuated during the diamicton deposition whereas the increase of TOC began with the lake formation during the postglacial period that started about 5,000 yr B.P. More notable are the distinct TOC peaks that may imply enhanced primary productivity during the warm period. The uniform and low TOC contents may reflect the limited productivity during the evolution of the lake. However, the recent TOC readvance clearly indicates gradual warming on King George Island. However, the paleoclimatic signature in the terrestrial lake environment during the Holocene seems to be subtle and less distinct, compared to the marine environment.
마이크로파 공진자용$Ba_{1-x}A_x(Mg_{1/3}Nb_{2/3})O_3$(A = Sr, Ca)
김부근,김재윤,김강언,정수태,조상희 한국전기전자재료학회 2000 전기전자재료학회논문지 Vol.13 No.6
The structural changes and the microwave dielectric properties of $Ba_{1-x}$/A$_{x}$/(Mg$_{1}$3//Nb$_{2}$3/)O$_3$(A=Sr, Ca=x0, 0.2, 0.4, 0.6, 0.8, 1.0) were investigated. The densities of samples are gradually decreased with increasing x(BMN=6.1, SMN=5.22 and CMN=4.26 g/m$^3$)The crystal structure of BMN was untilting of oxygen octahedral. The structural changes of BSMN showed the antiphase tilting at x>0.4, and those of BCMN showed the antiphase tilting at 0.2<x<0.8 and antiphase-inphase tilting at x>0.8. The variation of dielectric constant with Sr was small(BMN=32, SMN=30) However the variation with Ca was large the highest value was 42 at Ca=0.2(CMN=25) The maximum quality factor was 68,000 GHz at Sr=0.2 and the minimum quality factor was 3,000 GHz at Ca=0.2 (BMN=35,000, SMN=20,000 and CMN=23,000 GHz) The temperature coefficients of resonant frequency of BSMN were about 2 times larger than those of BCMN in all composition.ion.
김부근,Shigeyoshi Otosaka,박경애,Shinichiro Noriki 한국해양과학기술원 2018 Ocean science journal Vol.53 No.1
Investigation of sediment-trap deployments in the East/Japan Sea (EJS) showed that distinct seasonal variations in particulate organic carbon (POC) fluxes of intermediate-water sediment-traps clearly corresponded to changes in chlorophyll a concentrations estimated from SeaWiFS data. The prominent high POC flux periods (e.g., March) were strongly correlated with the enhanced surface-water phytoplankton blooms. Deep-water sedimenttraps exhibited similar variation patterns to intermediate-water sediment-traps. However, their total flux and POC flux were higher than those of intermediate-water sediment-traps during some months (e.g., April and May), indicating the lateral delivery of some particles to the deep-water sediment-traps. Distinct seasonal δ13C and δ15N variations in settling particles of the intermediate-water sediment-traps were observed, strongly supporting the notion of seasonal primary production. Seasonal variations in δ13C and δ15N values from the deep-water sediment-traps were similar to those of the intermediate-water sediment-traps. However, the difference in δ13C and δ15N values between the intermediate-water and the deepwater sediment-traps may be attributed to degradation of organic matter as it sank through the water column. Comparison of fluxweighted δ13C and δ15N mean values between the deep-water sediment-traps and the core-top sediments showed that strong selective loss of organic matter components (lipids) depleted in 13C and 15N occurred during sediment burial. Nonetheless, the results of our study indicate that particles in the deep-water sediment-trap deposited as surface sediments on the seafloor preserve the record of surface-water conditions, highlighting the usefulness of sedimentary δ13C and δ15N values as a paleoceanographic application in the EJS.
김부근,Buhan Song,조현구,Trevor Williams,Carlota Escutia 한국지질과학협의회 2017 Geosciences Journal Vol.21 No.1
On the basis of the variations of sediment properties such as biogenic opal, grain size, natural gamma radiation (NGR), and clay mineralogy, we differentiate two types of late Neogene marine sediments that record paleoclimate changes associated with the growth and retreat of the East Antarctic Ice Sheet (EAIS) and associated changes in sea ice cover. The first type of sediments are massive muds characterized by high biogenic opal (30~55%), low NGR (15~30 counts per second (cps)), large mean grain size (>8.3 μm), and low smectite/(illite + chlorite) [S/(I + C)] ratios (<~0.2). We interpret these sediments as the result from deposition by hemipelagic sedimentation during interglacial conditions. In contrast, the second type of sediments are laminated muds characterized by low biogenic opal (5~7%), high NGR (45~67 cps), small mean grain size (<6.3 μm), and high S/(I + C) ratios (>~0.2). We interpret these sediments as the result from deposition by either turbiditic or contouritic processes during glacial conditions. All these sediment properties indicate that the Wilkes Land continental rise recorded late Neogene paleoclimatic changes in terms of surface water productivity, sediment provenance and transport pathway, and depositional processes that are related to the growth and retreat of EAIS. In addition, the decreased maxima of biogenic opal content at Hole U1359A highlights the temporal climatic change between the late Pliocene (~2.0 Ma to ~3.7 Ma) and the early Pliocene to late Miocene (~3.7 Ma to ~6.3 Ma), confirming the important role of sea ice to the surface water productivity associated with the global cooling trend in the East Antarctica.
김부근,김여훈,김형직,형기성,유찬민 한국해양과학기술원 2010 Ocean and Polar Research Vol.32 No.1
Calcium carbonate (CaCO3) content was measured from 3 box core (BC060301, BC060303, BC070301) sediments, in addition to pilot core (PC313) sediments, from deep waters within the Western Pacific Ocean. At the two collection sites (BC060301, PC313) located close to the equator, downcore variation exhibited low CaCO3 content during the interglacial period and high CaCO3 content during the glacial period. Variation of coarse fraction (>63 μm) content also followed changes in CaCO3 content, indicating that dissolution effect of bottom water decreased during the glacial period. Such variation pattern is typical of the Pacific Ocean. However, downcore variation at the two collection sites (BC060303, BC070301) in the Philippine Sea contrasted the trend of the previous two cores (i.e., high CaCO3 content during the interglacial period and low during the glacial period). This pattern is typical of the Atlantic Ocean. Such results may be attributed to the increasing dilution effect, initiated possibly by the increased transportation of terrigenous materials from nearby continent and archipelago during the glacial period when sea level was low. Alternatively, it is possible that the non-carbonate biogenic particles may have been responsible for dilution. Because of these uncertainties, the record of CaCO3 variation in the deep Western Pacific Ocean is not regionally consistent.
남서태평양 리코후 드리프트 퇴적층의 쇄설성 실트입자 크기의 수직적 변화를 이용한 플라이스토세 후기 심해서안경계해류의 세기 변화
김부근,박유현,이영주,박장준 한국해양과학기술원 2006 Ocean and Polar Research Vol.28 No.4
Hole 1124 of ODP Leg 181 was located in the Rekohu sediment drift off eastern New Zealand in the southwest Pacific Ocean. Mean grain sizes of sortable silt were measured in two drilled cores (1124A and 1124B). Chronostratigraphy of core 1124 was correlated with the well-dated nearby core S931, resulting that the age of core 1124 covers the late Pleistocene spanning about MIS (Marine Isotope Stage) 5. Mean grain size of sortable silt seemed to be relatively large during the glacial period, whereas that of the interglacial period was smaller, although several tephra layers contain some coarse-grained pyroclatic particles. The variation in mean grain size of sortable silt in Rekohu sediment drift during the late Pleistocene indicates that the intensity of Deep Western Boundary Current (DWBC) might have been enhanced during the glacial period as a result of increased production of Antarctic Bottom Water (AABW).