• Journal of the korean society of oceanography
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• v.36 no.1
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• pp.19-26
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• 2001

The biological pump is one of the important pumping mechanisms absorbing CO$_2$ from the atmosphere into the ocean and can be quantified by estimating new production. New production in the open ocean mostly depends on the supply of nitrate from the water below the mixed layer. While nitrate is affected by many biological processes, the helium isotope ($^3$He) is inert and has very simple physical properties. Using the $^3$He flux and the relation between $^3$He and NO${_3}\;{^-}$- within the thermocline, the nitrate flux supporting new production was estimated in the southern East Sea. The average ${\delta}^3$He within the mixed layer was -14$%_o$ and -l5.4$%_o$ in the winter and autumn, respectively. Through the year excess $^3$He occurs in the mixed layer except for a slight depletion of -17$%_o$ in summer. The $^3$He flux of 13$%_o$md$^{-1}$ associated with the concentration gradient at the air-sea interface was calculated from the product of the piston velocity and the excess $^3$He. Tritium decay within the mixed layer could support only 2$%_o$md$^{-1}$ of the flux. Thus, the remaining 11$%_o$md^{-1}$ could be attributed to the flux of tritiugenic $^3$He from the water below the mixed layer. Nitrate and $^3$He were positively correlated within the thermocline layer with the slope of 0.21 ${\mu}$mol kg$^{-1}$ $%_o\;^{-1}$. The annual nitrate flux estimated from the upward flux of $^3$He and the NO$_{3}\;{^-}$-$^3$He relation was 0.8${\pm}$0.2 mol(N) m$^{-2}$yr$^{-1}$. This flux corresponds to an annual new production of 64 g(C) m$^{-2}$yr$^{-1}$, which is consistent with that in the north-west Pacific.

• Molecules and Cells
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• v.25 no.2
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• pp.231-241
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• 2008

Indole glucosinolates (IG) play important roles in plant defense, plant-insect interactions, and stress responses in plants. In an attempt to metabolically engineer the IG pathway flux in Chinese cabbage, three important Arabidopsis cDNAs, CYP79B2, CYP79B3, and CYP83B1, were introduced into Chinese cabbage by Agrobacterium-mediated transformation. Overexpression of CYP79B3 or CYP83B1 did not affect IG accumulation levels, and overexpression of CYP79B2 or CYP79B3 prevented the transformed callus from being regenerated, displaying the phenotype of indole-3-acetic acid (IAA) overproduction. However, when CYP83B1 was overexpressed together with CYP79B2 and/or CYP79B3, the transformed calli were regenerated into whole plants that accumulated higher levels of glucobrassicin, 4-hydroxy glucobrassicin, and 4-methoxy glucobrassicin than wild-type controls. This result suggests that the flux in Chinese cabbage is predominantly channeled into IAA biosynthesis so that coordinate expression of the two consecutive enzymes is needed to divert the flux into IG biosynthesis. With regard to IG accumulation, overexpression of all three cDNAs was no better than overexpression of the two cDNAs. The content of neoglucobrassicin remained unchanged in all transgenic plants. Although glucobrassicin was most directly affected by overexpression of the transgenes, elevated levels of the parent IG, glucobrassicin, were not always accompanied by increases in 4-hydroxy and 4-methoxy glucobrassicin. However, one transgenic line producing about 8-fold increased glucobrassicin also accumulated at least 2.5 fold more 4-hydroxy and 4-methoxy glucobrassicin. This implies that a large glucobrassicin pool exceeding some threshold level drives the flux into the side chain modification pathway. Aliphatic glucosinolate content was not affected in any of the transgenic plants.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.06a
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• pp.189-194
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• 2005

The evaporation heat transfer and pressure drop of $CO_2$ in a small diameter tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator(test section). The test section was made of a horizontal stainless steel tube with the inner diameter of 4.57 mm, and length of 4 m. The experiments were conducted at mass flux of 200 to 700 $kg/m^2s$, saturation temperature of $0^{\circ}C$ to $20^{\circ}C$, and heat flux of 10 to 20 $kW/m^2$ . The test results showed the evaporation heat transfer of $CO_2$ has great effect on more nucleate boiling than convective boiling. The evaporation heat transfer coefficients of $CO_2$ are highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation pressure drop of C02 are highly dependent on the mass flux. In comparison with test results and existing correlations, correlations failed to predict the evaporation heat transfer coefficient and pressure drop of $CO_2$, therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient and friction pressure drop of $CO_2$ in a horizontal tube.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.133-138
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• 2015

Pressure retarded osmosis (PRO) process is one of membrane processes for harvesting renewable energy by using salinity difference between feed and draw solutions. Power is generated by permeation flux multiplied by hydraulic pressure in draw side. Membrane fouling phenomena in PRO process is presumed to be less sever, but it is inevitable. Membrane fouling in PRO process decreases water permeation through membrane, resulting in significant power production decline. This study intended to investigate the effect of hydraulic pressure in PRO process on alginate induced organic fouling as high and low hydraulic pressures (6.5 bar and 12 bar) were applied for 24 h under the same initial water flux. In addition, organic fouling in draw side from the presence of foulant (sodium alginate) in draw solution was examined. As major results, hydraulic pressure was found to be not a significant factor affecting in PRO organic fouling as long as the same initial water flux is maintained, inidicating that operating PRO process with high hydraulic pressure for efficient energy harvesting will not cause severe organic fouling. In addition, flux decline was negligible from the presence of organic foulant in draw side.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.227-232
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• 2008

The present study was investigated the local heat transfer characteristics and temperature distribution on the louver fin by using the expansion model. Heat transfer rate, frost mass and temperature distribution of the louver fin under frosting condition were experimentally investigated. Local heat transfer rate and heat flux on the louver were analyzed by the conduction heat transfer between top and lower part of the louver. The experimental key parameter was brine inlet temperature(-5, -10, $-15^{\circ}C$). The heat transfer performance and frost mass at brine temperature of $-15^{\circ}C$ were increased by maximum 3 time than the brine temperature of $-5^{\circ}C$. At all experimental case, local heat transfer rate and heat flux of the louver were almost symmetry at the louver number of 6. Especially, local heat transfer rate and heat flux were maximum increased on the louver number of 4 and 8.

• Membrane and Water Treatment
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• v.10 no.2
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• pp.113-120
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• 2019

To investigate surface properties and interception performances of the new modified PVDF membrane coated with Graphene Oxide (GO) and nano-$TiO_2$ (for short the modified membrane) via the interface polymerization method combined with the pumping suction filtration way, filtration experiments of the modified membrane on Humic Acid (HA) were conducted. Results showed that the contact angle (characterizing the hydrophilicity) of the modified membrane decreased from $80.6{\pm}1.8^{\circ}$ to $38.6{\pm}1.2^{\circ}$. The F element of PVDF membrane surface decreased from 60.91% to 17.79% after covered with GO and $TiO_2$. O/C element mass ratio has a fivefold increase, the percentage of O element on the modified membrane surface increased from 3.83 wt% to 20.87%. The modified membrane surface was packed with hydrophilic polar groups (like -COOH, -OH, C-O, C=O, N-H) and a functional hydrophilic GO-polyamide-$TiO_2$ composite configuration. This configuration provided a rigid network structure for the firm attachment of GO and $TiO_2$ on the surface of the membrane and for a higher flux as well. The total flux attenuation rate of the modified membrane decreased to 35.6% while 51.2% for the original one. The irreversible attenuation rate has dropped 71%. The static interception amount of HA on the modified membrane was $158.6mg/m^2$, a half of that of the original one ($295.0mg/m^2$). The flux recovery rate was increased by 50%. The interception rate of the modified membrane on HA increased by 12% approximately and its filtration cycle was 2-3 times of that of the original membrane.

• Membrane Journal
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• v.14 no.3
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• pp.192-200
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• 2004

It is an anaerobic germ that Lactobacillus cell concentrated using ceramic membrane has high stability and long lifetime as compared with polymeric membrane. The effects of operating pressure, temperature, crossflow velocity on cell harvesting have been studied. Also the variation of flux and transmembrane pressure (TMP) with increasing concentration ratio and the change of TMP at constant concentration ratio (volumetric concentration factor: VCF) regarding the optimization have been examined. It showed that the permeate flux increased gradually with the increasing of transmembrane pressure, crossflow velocity, and volumetric concentration factor. The higher initial flux was due to the reduction of viscosity at elevated temperature. However, as operating time progressed, the effect of temperature was negligible since the effect of viscosity became minor. As a result, that operate in a constant concentration ratio, decreased degree could know that become slowly although the flux decreases according as operating time progressed. The flux is a very stable in the condition of constant VCF range. The yield of Latobaciilus (PS 406) which was cultivated at $37^{\circ}C$ was concentrated about 4.9{\times}10^9$ after operation.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.117-117
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• 2000

높은 광학적 투과성과 전기전도성을 갖는 ITO film은 solar cell같은 optoelectronic device나 휴대용 소형 TV, flat panel display 등의 투명전극으로 그 응용 분야가 광범위하여 많은 연구가 수행되어져 왔다. 기판으로서 유리를 사용할 때 생기는 활용범위 제한을 극복하고자 최근 유기물 위에 증착이 가능한 저온 증착방법에 대한 연구가 활발히 이루어지고 있다. 그 가운데 이온빔과 같은 energetic한 beam을 이용한 박막의 제조는 기판을 플라즈마 발생지역으로부터 분리시켜 이온빔의 flux 및 에너지, 입사각 등의 자유로운 조절을 통해 상온에서도 우수한 성질의 박막형성 가능성이 제시되어 지고 있다. ITO박막을 형성하는 방법 중 스프레이법이나 CVD법과 같은 화학적 증착방법은 증착시 350-50$0^{\circ}C$의 고온이 필요하고 현재 가장 많이 응용되어 지고 있는 sputter법은 15$0^{\circ}C$정도의 가열이 필요하므로 앞으로 응용가능성이 매우 커서 많은 연구가 진행중인 플라스틱과 아크릴 같은 flexible 한 기판위 증착에 적용이 불가능하다. 본 실험에서는 IBAD(Ion Beam Assisted Deposition)법을 이용하여 저온 ITO film을 유리와 유기막위에 증착하는 연구를 수행하였다. 유기막위에 증착된 ITO는 보다 가볍고 충격에 강하고 유리에 못지 않은 투과성을 가지고 있으나 현재 film의 quality 향상에 대한 요구가 증대되어 지고 있는 실정이다. 따라서, 본 실험에서는 dual oxygen ion gun의 조건변화에 따른 ITO film의 특성변화를 관찰하였다. 고정된 증？율에 한 개 ion gun에 ion flux를 고정시킨 후 또 다른 ion gun에서 발생하는 oxygen radical의 영향을 조사하였으며 oxygen radical의 rf power에 따른 변화는 OES(Optical emission spectroscopy)를 사용하였다. 너무 적은 oxygen ion beam flux나 oxygen radical은 film의 전도도 및 투과도를 저하시켰고 반면 너무 과도한 flux의 증가 시는 전도도는 감소하였고 투과도는 증가하는 경향을 보였다. 기판에 도달하는 oxygen ion flux는 faraday cup을 이용하여 측정하였으며 증착된 ITO film은 XPS, UV-spectrometer, 4-point probe를 이용하여 분석하였다.

• Journal of the Semiconductor & Display Technology
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• v.20 no.4
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• pp.72-77
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• 2021

The radial distribution of etch rate was analyzed using the ion energy flux model in VHF-CCP. In order to exclude the effects of polymer passivation and F radical depletion on the etching. The experiment was performed in Ar/SF6 plasma with an SF6 molar ratio of 80% of operating pressure 10 and 20 mTorr. The radial distribution of Ar/SF6 plasma was diagnosed with RF compensated Langmuir Probe(cLP) and Retarding Field Energy Analyzer(RFEA). The radial distribution of ion energy flux was calculated with Bohm current times the sheath voltage which is determined by the potential difference between the plasma space potential (measured by cLP) and the surface floating potential (by RFEA). To analyze the etch rate uniformity, Si coupon samples were etched under the same condition. The ion energy flux and the etch rate show a close correlation of more than 0.94 of R² value. It means that the etch rate distribution is explained by the ion energy flux.

• Korean Chemical Engineering Research
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• v.47 no.4
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• pp.481-487
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• 2009

In this of study, effects of input air velocity(0.05~0.22 m/sec) and molten carbonate salt temperature ($870{\sim}970^{\circ}C$) on flow regime transition have been studied by adopting a drift-flux model of air holdup and a stochastic analysis of differential pressure fluctuations in an air-molten sodium carbonate salt two-phase system(molten salt oxidation process). Air holdup where the flow regime transition begins was determined by air holdup-drift flux plot. The air holdup value which the flow regime transition begins was increased with increasing molten carbonate salt temperature due to the decrease of viscosity and surface tension of molten carbonate salt. To characterize the flow regime transition more quantitatively, differential pressure fluctuation signals have been analyzed by adopting the stochastic method such as phase space portraits and Kolmogorov entropy, The Kolmogorov entropy decreased with an increasing of molten carbonate salt temperature but increased gradually with an increase in an air velocity, however, it exhibited different tendency with the flow regime and the air velocity value which flow regime transition begins was same to the results of drift-flux analysis.