• Title/Summary/Keyword: Mixing zone

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Distribution and Behavior of Soil CO2 in Pohang area: Baseline Survey and Preliminary Interpretation in a Candidate Geological CO2 Storage Site (포항 지역 토양 CO2의 분포 및 거동 특성 연구: CO2 지중저장 부지 자연 배경 조사 및 예비 해석)

  • Park, Jinyoung;Sung, Ki-Sung;Yu, Soonyoung;Chae, Gitak;Lee, Sein;Yum, Byoung-Woo;Park, Kwon Gyu;Kim, Jeong-Chan
    • Journal of Soil and Groundwater Environment
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    • v.21 no.1
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    • pp.49-60
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    • 2016
  • Distribution and behavior of baseline soil CO2 were investigated in a candidate geologic CO2 storage site in Pohang, with measuring CO2 concentrations and carbon isotopes in the vadose zone as well as CO2 fluxes and concentrations through ground surface. This investigation aimed to assess the baseline CO2 levels and to build the CO2 monitoring system before injecting CO2. The gas in the vadose zone was collected using a peristaltic pump from the depth of 60 cm below ground surface, and stored at gas bags. Then the gas components (CO2, O2, N2, CH4) and δ13CCO2 were analyzed using GC and CRDS (cavity ringdown spectroscopy) respectively in laboratory. CO2 fluxes and CO2 concentrations through ground surface were measured using Li-COR in field. In result, the median of the CO2 concentrations in the vadose zone was about 3,000 ppm, and the δ13CCO2 were in the wide range between −36.9‰ and −10.6‰. The results imply that the fate of CO2 in the vadose zone was affected by soil property and vegetations. CO2 in sandy or loamy soils originated from the respiration of microorganisms and the decomposition of C3 plants. In gravel areas, the CO2 concentrations decreased while the δ13CCO2 increased because of the mixing with the atmospheric gas. In addition, the relation between O2 and CO2, N2, and the relation between N2/O2 and CO2 implied that the gases in the vadose zone dissolved in the infiltrating precipitation or the soil moisture. The median CO2 flux through ground surface was 2.9 g/m2/d which is lower than the reported soil CO2 fluxes in areas with temperate climates. CO2 fluxes measured in sandy and loamy soil areas were higher (median 5.2 g/m2/d) than those in gravel areas (2.6 g/m2/d). The relationships between CO2 fluxes and concentrations suggested that the transport of CO2 from the vadose zone to ground surface was dominated by diffusion in the study area. In gravel areas, the mixing with atmospheric gases was significant. Based on this study result, a soil monitoring procedure has been established for a candidate geologic CO2 storage site. Also, this study result provides ideas for innovating soil monitoring technologies.

The Overview of Layered structures in Mafic - Ultramafic Macheon Intrusion (고철질-초고철질 마천관입암의 층상구조 개관)

  • Song, Yong-Sun;Kim, Dong-Yeon;Park, Kye-Hun
    • The Journal of the Petrological Society of Korea
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    • v.16 no.3
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    • pp.162-179
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    • 2007
  • Macheon Layered Intrusion (MLI) which intruded into Precambrian gneiss complex of the northern Jirisan area, southeastern part of Youngnam (or Sobaeksan) Massif, is a layered mafic-ultramafic complex of Triassic age (ca. 223 Ma). The MLI is divided into Layered Series and Laminated Series. Layered Series is subdivided into Central Zone (Lower Zone) consisting of olivine gabbros and Peripheral Zone (Middle or Upper Zone) consisting of hornblende gabbros based on the type of cumulus texture and the main mafic phase. The Central Zone of Layered Series comprises thinly laminated olivine gabbros and uniform or thickly laminated coarse olivine gabbros which consist of mela-gabbro, troctolite, leuco-troctolite, and anorthositic rocks. Laminated Series is also subdivided into quartz-bearing biotite-pyroxene gabbros and homblende diorite and both have variable amount of interstitial quartz and microcline. Laminated series display moderately to slightly developed igneous lamination which is defined by the planar alignment of lath-shape plagioclases. Chilled margin of quartz-bearing biotite-pyroxene gabbro with surrounding Precambrian gneisses insists shallower intrusion of more felsic cognate magma evolved in the deep a little later. Rocks of Layered Series have orthocumulus to adcumulus olivine, adcumulus to intercumulus plagioclase, and intercumulus to heteradcumulus pyroxene and hornblende. Magmatic modally grading, folding, and cross-lamination are not rarely occurred in thinly layered rocks. These textural characteristics define main mechanisms of the formation of layered and laminated structure in mafic-ultramafic rocks of Macheon Layered Intrusion are gravity settling and in-situ crystallization associated with slumping and density current.

Is Nitrogen Uptake Rate by Phytoplankton below the Euphotic Zone in the Yellow Sea Considerable? (황해의 무광대에서 식물플랑크톤에 의한 질소 섭취율은 상당한가?)

  • Yang, Sung-Ryull;Shim, Jae-Hyung;Chung, Chang-Soo;Hong, Gi-Hoon;Pae, Se-Jin;Yang, Dong-Beom;Park, Myung-Gil
    • The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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    • v.7 no.2
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    • pp.60-67
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    • 2002
  • To determine whether nitrogen (N) uptake by phytoplankton below the euphotic zone in the Yellow Sea is considerable, we measured the uptake rates of nitrate and ammonium using $^{15}N$-labeled stable isotope $K^{15}NO_{3}$ and $^{15}NH_{4}Cl$, in May and November 1997 at total 10 stations. Depth-integrated uptake rates of nitrate and ammonium over the euphotic zone during this study ranged from 1.8 to 15.3 mg N $m^{-2}$ $d^{-1}$ and from 5.0 to 132.2 mg N $m^{-2}$ $d^{-1}$, respectively, and ammonium uptake predominated at 9 of 10 stations (1.9-19.4 fold). Depth-integrated uptake rates of nitrate and ammonium over the whole water column ranged from 2.9 to 22.0 mg N $m^{-2}$ $d^{-1}$ and from 15.7 to 175.5 mg N $m^{-2}$ $d^{-1}$, respectively. The significant proportion of whole water column N uptake was attributed to uptake by phytoplankton below the euphotic zone, ranging from 13.0 to 86.2% for nitrate and from 13.8 to 67.8% for ammonium, indicating that phytoplankton N uptake below the euphotic zone is at times considerable in the study area. The results suggest that when phytoplankton below the euphotic zone in the Yellow Sea are again entrained into the euphotic zone by a certain physical forcing such as turbulent mixing and the vertical movement of thermocline, these episodic events may significantly affect the material fluxes within the euphotic zone. Furthermore, the results suggest that a portion of regenerated production estimated from $^{15}N$-ammonium uptake should be included in new production estimates, which otherwise could be underestimated in the Yellow Sea.

Image Mixing in Multiview 3 Dimensional Imaging Systems (다시점 3차원 영상 시스템에서 영상혼합)

  • Kim, Shin-Hwan;Son, Jung-Young
    • Journal of Korea Multimedia Society
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    • v.11 no.2
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    • pp.175-181
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    • 2008
  • A 2 dimensional quality function for quantifying the quality of images observed at viewing regions in contact-type multiview 3 dimensional imaging systems is devised and its effectiveness is verified experimentally. The function allows calculating the locations of viewing regions for patched images of any number of different view images. The images observed at the calculated regions reveal that different parts of the display panel of the system project different view images and match with the function's prediction.

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Numerical simulation of unsteady flow field behind bluff body (Bluffbody 비정상 유동장에 대한 수치해석)

  • Ryu, Myeong-Seok;Gang, Seong-Mo;Kim, Yong-Mo
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.3
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    • pp.350-357
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    • 1997
  • The transient incompressible flow behind the axisymmetric bluff body is numerically simulated using the random vortex method(RVM). Based on the vorticity formulation of the unsteady Navier-Stokes equations, the Lagrangian approach with a stochastic simulation of diffusion using random walk technique is employed to account for the transport processes of the vortex elements. The numerical solutions for 2-dimensional recirculating flow behind a backward-facing step in the laminar range of Reynolds number are compared with experimental data. The present simulation focuses on the transitional flow regime where the recirculation zone behind the bluff body becomes highly unsteady and large-scale vortex eddies are shed from the bluff body wake due to intrinsic shear layer instabilities. The unsteady vertical flow structures and the mixing characteristics behind the bluff body are discussed in detail.

Flame Characteristics on Wall Recess Type Ceramic Combustor for Low Pollutants (Wall Recess형 저공해 세라믹 연소기의 화염특성)

  • 전영남;채재우
    • Journal of Korean Society for Atmospheric Environment
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    • v.12 no.2
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    • pp.131-139
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    • 1996
  • The developent of ceramic combustor is being increased beca- use of the excellent physical properties of ceramic material, that is, high-resistant strength, high emissivity power and high corrosin-resistance. Ceramic combustor has been interested in the application of ultra-lean combustion for low NO$_{x}$ emission and gaseuos waste incineration with good combustion. This experimental study was conducted to investigate the combustion and emission characteristics of wall recess type ceramic combustor with equivalence ratio, mixture flow velocity and wall recess depth as parameters. The results in this study are as follows: 1. Wall recess played a important role to extend flame stability region. 2. The peak temperature of gas was peoportional to equivalence ratio, mixture flow velocity and wall recess depth. 3. The static pressure of mixing chamber and inlet temperature depended on the position of flame zone. 4. NO reduction was achieved by lean mixture without lower combustibility.y.

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Experimental Study on Upstream Fueled Cavity Flame-Holder Scramjet Engine (상류 분사 공동 화염 지지부를 가지는 스크램제트 엔진에 관한 실험적 연구)

  • Jeong, Eun-Ju;Jeung, In-Seuck;O'Byrne, Sean;Houwing, A.F.P.
    • Journal of the Korean Society of Combustion
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    • v.11 no.4
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    • pp.1-8
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    • 2006
  • The model cavity scramjet engine experiments are carried out using T3 free-piston shock tunnel. Upstream hydrogen fuel is injected before the cavity with different injection pressure. OH planar laser-induced fluorescence is used to investigate the combustion zone and piezoelectric pressure transducers are used to define the pressure rise due to the combustion. Main combustion region is a mixing layer which is between air and fuel. Also high OH fluorescence signal is appeared in the shear layer above the cavity in high equivalence ratio. From the OH signal in the cavity, this fuel injection system can be a role as a flame-holder.

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Formation of TiC Composite Layer on Ductile Iron by Laser Surface Modification (레이저 처리에 의한 구상흑연주철의 TiC 복합화에 관한 연구)

  • Kim, Woo-Yeol;Park, Heung-Il
    • Journal of Korea Foundry Society
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    • v.18 no.6
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    • pp.593-603
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    • 1998
  • Commercial ductile iron was coated with titanium and aluminum powders by low pressure plasma spraying and then irradiated with a $CO_2$ laser to produce anti-corrosive TiC composite layer. TiC carbides were precipitated homogeneously in a laser alloyed layer by in-situ reaction between carbon existed in the base metal and titanium with thermal sprayed coating. The formation of gas pores and brittle limited mixing zone with ledeburite microstructure in TiC composite layer were surpressed by the complementary alloying of aluminum. The hardness of TiC composite layer obtained by addition of titanium and aluminum was between 600 and 660 Hv, which was three times as high as the hardness of ferritic ductile iron. From the results of isothermal oxidation at 1123k for 24 hours in air, high temperature oxidation resistance of the TiC composite layer with aluminum was improved and doubled when compared with the TiC composite layer without aluminum.

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UPWELLING FILAMENTS AND THEIR ROLE IN CROSSFRONTAL WATER EXCHANGE

  • Kostianoy, A.G.;Soloviev, D.M.
    • Proceedings of the KSRS Conference
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    • v.2
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    • pp.954-957
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    • 2006
  • Satellite data (thermal and color imagery) show that offshore flowing filaments off the west coasts of North America, North and South Africa can influence significantly the cross-frontal mixing in the coastal upwelling zones. To evaluate this role, we investigated structure, dynamics and behavior of surface filaments in the Canary and Benguela upwelling regions on the base of daily satellite IR and VIS imagery (AVHRR NOAA, MODIS-Aqua). It was found that seasonal variability of the filaments location depends on intra-annual shift of general upwelling intensity along the coast. The main statistical characteristics of filaments - length, width, temperature anomaly and estimates of velocity were obtained. Estimates of cross-frontal water exchange due to filamentation based on the statistical data show that these coherent structures play a major role in the water and particle exchange between coastal zone and the open ocean in both upwelling regions.

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Observations on seaweed attachment to bivalve shells in Peter the Great Bay (East Sea) and their taphonomic implications

  • Lutaenko, Konstantin A.;Levenets, Irina R.
    • The Korean Journal of Malacology
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    • v.31 no.3
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    • pp.221-232
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    • 2015
  • Observations in beach, intertidal and upper subtidal environments in Peter the Great Bay (north-western East Sea) have shown that attached algae were found on empty shells of 13 species of epifaunal and infaunal bivalve mollusks. Thirteen algae species were identified on empty dislodged shells but more than 50 species are known to be epibiotic on living bivalves. The dislodgement of shells with attached algae takes place in semi-enclosed, low-energy areas, as well as those which are open and affected by strong wave action, indicating the large scale of this phenomenon. The significance of seaweed transportation of living mollusks and their empty shells in the coastal zone, involving both taphonomic and ecological processes, is stressed. Algae appear to be a taphonomic agent and play a similar role as compared to birds or hermit crabs, but they act passively and contribute to environmental mixing in death assemblages in coastal environments.