• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.29-32
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• 2004

Gaseous partitioning tracer test has been used for determining the volume and spatial distribution of residual non-aqueous phase liquid (NAPL) in the unsaturated soils. In this study, an experimental method for measuring the content of gas-exposed NAPL as well as that of total NAPL in a sand during air sparging was developed. Two different gaseous phase NAPL-partitioning tracers were used; n-pentane, with very low water solubility, was used as the tracer that partitions into NAPL that is only in contact with the mobile gas, and chloroform, with fairly good water solubility, was selected for detecting total NAPL content in the sand. Helium and difluromethanewere used as the non- reactive tracer and water-partitioning tracers, respectively. Using n-decane as a model NAPL (NAPL saturation of 0.018), 25.6% of total NAPL was detected by n-pentane at the water saturation of 0.68. Oniy 9.1% of total NAPL was detected by n-pentane at the water saturation of 0.84. This result implies that the quantity of gas-exposed NAPL increased about three times when the water saturation decreased from 0.84 to 0.68. At the water saturation of 0.68, more than 90% of total NAPL was detected by chloroform while 65.8% of total NAPL was detected by chloroform at the water saturation of 0.84. Considering that the removal rate of NAPL during air sparging for NAPL-contaminated aquifer is expected to be greatly dependent upon the spatial arrangement of NAPL phase with respect to the mobile gas, this new approach may provide useful information for investigating the mass transfer process during air-driven remedial processes fer NAPL-contaminated subsurface environment.

• Asian Journal of Atmospheric Environment
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• v.11 no.1
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• pp.1-14
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• 2017

For the quantitative analysis of volatile organic compounds (VOC), the use of a proper solvent is crucial to reduce the chance of biased results or effect of interference either in direct analysis by a gas chromatograph (GC) or with thermal desorption analysis due to matrix effects, e.g., the existence of a broad solvent peak tailing that overlaps early eluters. In this work, the relative performance of different solvents has been evaluated using standards containing 19 VOCs in three different solvents (methanol, pentane, and hexane). Comparison of the response factor of the detected VOCs confirms their means for methanol and hexane higher than that of pentane by 84% and 27%, respectively. In light of the solvent vapor pressure at the initial GC column temperature ($35^{\circ}C$), the enhanced sensitivity in methanol suggests the potential role of solvent vapor expansion in the hot injector (split ON) which leads to solvent trapping on the column. In contrast, if the recurrent relationships between homologues were evaluated using an effective carbon number (ECN) additivity approach, the comparability assessed in terms of percent difference improved on the order of methanol (26.5%), hexane (6.73%), and pentane (5.24%). As such, the relative performance of GC can be affected considerably in the direct injection-based analysis of VOC due to the selection of solvent.

• Applied Chemistry for Engineering
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• v.8 no.2
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• pp.220-229
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• 1997

Extraction of valuable light hydrocarbon from atmospheric residue using pentane as a solvent has been carried out. The SIMDIS was used to calculate the true boiling point of atmospheric residue containing complex components before the modeling of the extraction process could by performed. In order to simplify the procedure, modeling was adopted and a lumping method was used, such that a large number of compounds were divided into similar component classes called pseudocomponents. The modeling of the extraction process of the atmospheric residue-pentane system was based on the isothermal flash calculation, and the Peng-Robinson equation of state was used to calculate the fugacity coefficient of vapor and liquid phase during calculation steps of modeling. The agreement between the experiments and the calculations was reasonable considering the uncertainties involved in modeling such complex processes.

• Journal of Biosystems Engineering
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• v.29 no.6 s.107
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• pp.521-530
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• 2004

The solar powered water pump is very ideal equipment because solar power is more intensive when the water is more needed in summer and it is very helpful in the rural area, in which electrical power is not available. The average solar radiation power is $3.488\;kWh/(m^2{\cdot}day)$ in Korea. In this study, the experimental system of the water pump driven by the radiation energy were designed, assembled, tested and analyzed fur realizing the solar powered water pump. Energy conversion ken radiation energy to mechanical energy by using n-pentane as operating material was done and the water pumping cycles were able to be continued. The quantity of the water pumped per cycle ranged from 2 L to 10 L depending on the level of the valve open area far the vapour supply. The average quantity was about 4,366 cc. The thermal efficiency was about $0.018\%$. The pressure level of the n-pentane vapour in flash tank was about $110\~150\;kPa$ and that in the water tank was $93\~130\;kPa$. The pressure in the condenser during cycles was maintained as about 70 kPa. The condensation of the n-pentane vapour in the water tank was increased with the cycles even though the internal and external insulation were done. Air tank performance was better with increasing of the water piston displacement and the water could be pumped with the water piston displacement becoming higher than 6,500 cc.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.1-7
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• 2004

The physical properties of rigid polyurethane foam(PUF) synthesized using various types of blowing agents such as water, HFC-365mfc, HFC-245fa, HCFC-l4lb, CFC-11 and n-pentane were studied. The blending effect of blowing agents were also studied. The thermal conductivity, reaction rate, and cell morphology of the PUF with various blending ratio of blowing agents were investigated. The PUF blown by water shows the highest compressive strength among other single blowing agents. The thermal conductivity of PUFs blown by HFC-245fa and HFC-365mfc are close to that of PUFs blown by CFC-11. When HFC-365mfc was mixed with HFC-245fa(30mo1e$\%$) as coblowing agent, the mechanical property shows the highest value among other coblowing agents. It is that the thermal conductivity of PUFs depends on cell size of PUFs as well as thermal conductivity of blowing agent in gaseous form.

• Journal of Bio-Environment Control
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• v.19 no.3
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• pp.147-152
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• 2010

Poor fruit set during winter period is one of the biggest problem in plastic tunnel watermelon cultivation. Hand pollination is inevitable to maximize fruit set of the winter watermelon. Productivity and viability of pollen grain and organic solvents for pollen storage were investigated. All cultivars produced more than 10 mg/flower except for 'Kumchun' cultivar. Pollen amount per flower were 13.8 mg in 'Bok' and 12.1 mg in 'Speedkul'. Germination rate of pollen grains incubated at $30^{\circ}C$ right after soaking in pentane solvent were 76% in 'Kumchun' as the lowest and 92% in 'Apollokul' as the highest. The pollen of 'Bok' showed the highest germination rate by 75% after a 15-day storage in pentane. All cultivars showed their pollen germination rate below 25% after a 24-day storage. Among the cuitivars, speed of pollen tube growth in vitro were relatively lower in 'Kumchun' and 'Sambokkul' by below $50\;{\mu}m/hr$. Pollen tube of these cultivars tended to burst during its elongation on the medium. Pollen stored 24 hrs in organic solvents showed 45, 39, 34, 23, and 19% of germination in pentane, ethyl ether, n-hexane, ethyl acetate, and acetone, respectively. Compared with light condition, pollen viability was higher in darkness during pollen storage in organic solvents. Pollen grain was susceptible to the organic solvent. The viability of pollen grains seems to be influenced greatly by duration of soaking pollen in organic solvent and the polarity of solvents. Organic solvent damages surface of pollen grain and extent of damage was varied by the solvents.

• Membrane Journal
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• v.29 no.2
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• pp.111-121
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• 2019

An organic citrate series draw solute was synthesized using diethyl malonate for forward osmosis. The structure of the final compound potassium pentane-1,3,3,5-tetracarboxylate was confirmed by $^1H-NMR$ and $^{13}C-NMR$ analysis. Osmotic pressure, solubility, water permeability and reverse salt flux were measured for the properties of the draw solute. Forward osmosis results showed that the draw solute exhibited higher water flux than other draw solutes of trisodium citrate and tripotassium citrate. Reverse salt flux of all the organic daw solutes was much lower than that of NaCl. The osmotic pressure of the synthesized draw solute was 25% lower than that of NaCl. The solubility of the draw solute was 317 g/ 100 g water, which is 8.8 times higher than that of NaCl. A commercialized nanofiltration membrane was used for the recovery of the draw solute. The draw solute could be effectively recovered at low pressure.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1315-1322
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• 2006

The following study describes the gas chromatography-mass spectrometry (GC-MS) based screening and confirmation analysis of urinary androgenic steroids. Four commercially available solid-phase extraction (SPE) cartridges, Serdolit PAD-1, Sep-pak $C_{18}$, amino-propyl, and Oasis HLB, and three different extractive organic solvents, diethyl ether, methyl tert-butyl ether (MTBE), and n-pentane, were tested for sample preparation. Overall, Oasis HLB combined with MTBE extraction provided the highest recoveries in 39 of 46 total androgenic steroids examined and it showed a good extraction yield (>82.1%) for polar steroids, such as metabolites of fluoxymesterone, oxandrolone, and stanozolol, which gave a poor recovery in both n-pentane (9.2-64.3%) and diethyl ether (22.2-73.6%) extractions. All SPE sorbents tested showed potential, because they were efficient in extraction for most or selective steroids. When applied to positive urine samples based on the results obtained, the present method allowed selective and sensitive analysis for detection of urinary androgenic steroids. The experiments showed that the high-resolution MS method is clearly more efficient than the low-resolution MS technique for the detection of many urinary steroids. However, comprehensive sample clean-up procedures also might be needed especially in confirmation analysis to increase detectability.

• Journal of the Korean Chemical Society
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• v.58 no.2
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• pp.169-178
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• 2014

A new series of metal complexes of V(IV), Pd(II), Pt(IV), Ce(IV) and U(VI) with 3-[(3-chlorophenyl)-hydrazono]-pentane-2,4-dione (Cphpd) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment measurements, UV-vis, FT-IR and $^1H$ NMR as well as TG-DTG techniques. The data indicated that the Cphpd acts as a bidentate ligand through the hydrazono nitrogen and one keto oxygen. The kinetic parameters have been evaluated by using Coats Redfern (CR) and Horowitz-Metzeger (HM) methods. The thermodynamic data reflected the thermal stability for all complexes. The calculated bond length and the bond stretching force constant, F(U=O), values for $UO_2$ bond are $0.775{\AA}$ and $286.95Nm^{-1}$. The bond lengths, bond angles, dipole moment and the lowest energy model structure of the complexes have been determined with DFT calculations. The antimicrobial activity of the synthesized ligand and its complexes were screened.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.183-188
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• 2005

This study targets to investigate thermal wave transfer in a droplet strongly coupled with acoustic pressure and its effects on combustion response. The one-dimensional vaporization model uses SRK equation of state and flash calculation method to obtain more accurate thermophysical properties and compute vapor-liquid equilibrium. Calculations of an n-pentane droplet exposed into a perturbing nitrogen gas is carried out in terms of different ambient gas pressures and wave frequencies. The thermal wave is transferred more effectively at lower frequencies, which results in the decrease in the amplitude of the response.