• Journal of Soil and Groundwater Environment
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• v.24 no.3
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• pp.24-35
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• 2019

It is known that ${\delta}^{13}C_{DIC}$ (carbon-13 isotope of dissolved inorganic carbonate (DIC) ions) of water increases when dissolved $CO_2$ degases. However, ${\delta}^{13}C_{DIC}$ could decrease when the pH of water is lower than 5.5 at the early stage of degassing. Laboratory experiments were performed to observe the changes of ${\delta}^{13}C_{DIC}$ as $CO_2$ degassed from three different artificial $CO_2$-rich waters (ACWs) in which the initial pH was 4.9, 5.4, and 6.4, respectively. The pH, alkalinity and ${\delta}^{13}C_{DIC}$ were measured until 240 hours after degassing began and those data were compared with kinetic isotope fractionation calculations. Furthermore, same experiment was conducted with the natural $CO_2$-rich water (pH 4.9) from Daepyeong, Sejong City. As a result of experiments, we could observe the decrease of DIC and increase of pH as the degassing progressed. ACW with an initial pH of 6.4, ${\delta}^{13}C_{DIC}$ kept increasing but, in cases where the initial pH was lower than 5.5, ${\delta}^{13}C_{DIC}$ decreased until 6 hours. After 6 hours ${\delta}^{13}C_{DIC}$ increased within all cases because the $CO_2$ degassing caused pH increase and subsequently the ratio of $HCO_3{^-}$ in solution. In the early stage of $CO_2$ degassing, the laboratory measurements were well matched with the calculations, but after about 48 hours, the experiment results were deviated from the calculations, probably due to the equilibrium interaction with the atmosphere and precipitation of carbonates. The result of this study may be not applicable to all natural environments because the pressure and $CO_2$ concentration in headspace of reaction vessels was not maintained constant as well as the temperature. Nevertheless, this study provides fundamental knowledge on the ${\delta}^{13}C_{DIC}$ evolution during $CO_2$ degassing, and therefore it can be utilized in the studies about carbonated water with low pH and the monitoring of geologic carbon sequestration.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.6
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• pp.609-614
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• 2014

In this research, results of measuring temperature and relative humidity of underground-air-heat in Jeju showed $15{\sim}18^{\circ}C$ and 70~80% each which are somewhat high compare to other regions. So the Multi-effect dehumidifying and heating Heat Pump system which has merged functions of dehumidification and heating is made to solve this problem mentioned previously. When the suction air was $15^{\circ}C$ with 60% humidity, the outcome was 1.70 on $COP_h$ and 1.797(kg/h) on total amount of dehumidification, and also showed 1.87 $COP_h$ with 1.87 total amount of dehumidification under the condition of $20^{\circ}C$ and 80% humidity of suction air. Furthermore, $COP_h$ showed increased number which is 1.87 and also total amount of dehumidification increased which was 3.269(kg/h). The highest COP can be achieved at $17^{\circ}C$ and 70% relative humidity condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.60-68
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• 1997

Rayleigh Scattering Cross Sections($\sigma$i) of various gases and the temperature distributions of premixes C3H8/O2 flame are measured by high power KrF(248nm) Exci- mer laser and ICCD camera. Results show that $\sigma$i of O2 and Propane(C3H8) gases agree well in the 5% error range, but of H2 has the more or less difference from the calcul- ated value by other groups. This is attributed to the low RS signal of H2 to Nosie level(S/N ratio). The temperature distributions of flame range out between 300K in the air and about 2000K in the burned area. In this temperature range, out system has the about 250K temperature resolution. Because low RS signals in the reaction area with high temperature are affected highly by noises, temperature uncertainty of this area is relatively high to another part of flame. Experimental results show that UV Rayleigh Scattering can be used for the measurement of mixing ratio of mixed gases and the temperature distributions of flame. Especially, this technique can be applied for the measurement of the mixing ratio of air/fuel before the ignition and the flame structure after the ignition inside the Engine.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.111-116
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• 2008

Collapsed perflurostearic acid (PFS) films were prepared on the different pH and the various metal ion ($Na^+$, $Ca^{2+}$, $La^{3+}$) containing subphase using Langmuir-Blodgett (LB) trough. The degree of ionization of collapsed PFS film formed from floating monolayer has been determined by Fourier transform infrared (FTIR) spectroscopy. The intensity of C = O of -COOH peaks of collapsed PFS decreased with increasing pH of subphase. The order of ionization of collapsed PFS on the subphase of the same pH was $La^{3+}$ > $Ca^{2+}$ > $Na^+$. The degree of ionization of collapsed PFS on the Deionized (D.I.) water subphase is above 50% even at subpahse pH 3, which is much higher degree of ionization than that of stearic acid.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.6
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• pp.666-673
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• 1998

Solubilities (LiBr+$CaC1_2$) in water were measured at temperatures form 267.51 to 306.17K for $CaC1_2$ (LiBr+$CaC1_2$)=0.24 by mole. Experimental data were correlated with polynomial equations. Average absolute deviations between the measured and calculated values were 0.31% at concentration smaller than 60wt% and 0.41% at concentration larger than 60wt%, respectively. Vapor pressures were measured at temperatures from 296.75 to 436.75K and concentrations from 40 to 70wt%. Vapor pressure data were fitted to a Antoine-type equation and average absolute deviation was 2.98%. The P-T-X chart and H-T-X chart of $H_2O$/(LiBr+$CaC1_2$) system were constructed by using the correlation equations of solubility, vaper pressure, and heat capacity. The P-T-X chart indicates that $H_2O$/(LiBr+$CaC1_2$) system has potential as a possible working fluid for air-cooled absorption chillers.

• Journal of Power System Engineering
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• v.17 no.4
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• pp.58-63
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• 2013

This paper presents the new cascade liquefaction cycles using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$. The performance of the cascade liquefaction cycles with respect to temperature differences in the LNG heat exchangers is analyzed using HYSYS software and then compared the performance of these cycles with phillips optimized cascade liquefaction cycle. The coefficient of performance of the new liquefaction cycles considered in this study decreases with the temperature differences in the LNG heat exchangers, but the compressor work, expander work and heat capacity in the LNG heat exchanger increases, respectively. From the comparison of performance of three cycles, the cascade liquefaction cycles using $CO_2-C_2H_6-N_2$ showed the highest COP. And the cycles using $CO_2-C_2H_6-N_2$ and $CO_2-N_2O-N_2$ presented the second and third highest COP, respectively. In the view of performance, the optimized cascade liquefaction cycle using $C_3H_8-C_2H_4-C_1H_4$ yields much better COP. But, in the environment view, it is found that the cascade liquefaction cycle using $CO_2-C_2H_6-N_2$ shows favorable characteristics.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.251-258
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• 2003

The effects of the salt and the precursor pH on the synthesizing behavior and the morphology of mullite have been studied. Two kinds of mullite precursor sols were prepared by the dissolution of two kinds of salt (aluminum nitrate enneahydrate, Al($NO_3$)$_3$ㆍ$9H_2$O; type I and aluminum sulfate 14∼18 water, (SO$Al_4$)$_3$$\cdot$$14∼18H_2$O; type II) into the mixture of colloidal silica sol, respectively. Precursor pH of the sols was controlled to the acidic (pH= 1.5∼2) and basic (pH= 8.5∼9) conditions. The co-products with nitrate and sulfate were completely eliminated at $500^{\circ}C$ and $850^{\circ}C$, respectively, which was confirmed by TG/DTA results. The synthesizing temperature of mullite phase was found to be above $1200^{\circ}C$ for pH= 1.5∼2 and above $1300^{\circ}C$ for pH= 8.5∼9 in type I. However, in type II, the synthesizing temperature of mullite was decreased to $850^{\circ}C$ for pH= 1.5∼2 and $1100^{\circ}C$ for pH= 8.5∼9. The grain size of the mullite synthesized at pH= 8.5∼9 was larger than that at pH= 1.5∼2 in overall heat-treated temperatures, showing smaller grain size in type II. Aspect ratio of the mullite grains was more increased at pH= 1.5∼2 than pH= 8.5∼9 in type I, showing similar aspect ratio at both pH conditions in type II. It was found that the synthesizing temperature and grain size were predominantly governed by the initial precursor pH and decomposition of the salt, with minor effect on the grain morphology.

• Journal of Environmental Science International
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• v.6 no.5
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• pp.473-480
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• 1997

Microorganisms producing bioemulslfiler were isolated from the sea water In Pusan coastal area. The isolated strain which had the highest emulsification activity and stability was identified as the genus Achetobacter from the results of morphological. cultural and biochemical tests and named Achetobacter sp. EL-C6 for convenience. The compositions of optimum medium for emulsification of crude oil by Acinetobacter sp. EL-C6 were crude oil 2.0%, NH4NO3 0.2%, $K_2HPO_4$ 0.01%, $MgSO_4$.$7H_2O$ 1.o%, $CaCl_2$.$2H_2O$ 0.1% and NaCl 3.0% at initial pH 7.5 and 3$0^{\circ}C$, respectively. The cultivation for emulsification of crude ell was carried out in 500m1 shaking flask containing 100m1 of the optimum medium at 3$0^{\circ}C$. The highest emulsification was observed after 5 days. The utilization on the various hydrocarbon of the Achetobacter sp. EL-C6 showed that utilization of n-alkane compounds were better than that of aromatic compounds. Among the petroleum compounds, crude ell was best utilized by the Achetobacter sp. EL-C6.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.980-984
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• 1994

Monomeric rhodium and iridium diimine complexes $Cp^*M(HNRNH)(Cp^*$ = 1,2,3,4,5-pentamethylcyclopentadienyl : (M=lr; R=o-$C_6H_4 (1a), 4,5-(CH_3)_2-C_6H_2-1,2 (1b), 4,5-(Cl)_2-C_6H_2-1,2$ (1c), NCC=CCN-1,2 (1d): M=Rh; R=NCC=CCN-1,2 (1e)) have been synthesized from $[CP^*MCl_2]_2$ and 2 equiv. of diamine in the presence of $NEt_3$. The Crystal structure of 1a was determined by X-ray diffraction method : 1a was crystallized in the monoclinic system, space group $P2_{1/c}$, with lattice constants a=9.543 (1) ${\AA}$, b=16.286 (1) ${\AA}$, c=10.068 (1) ${\AA}$ and ${\beta}$=99.25 (1), with Z= 4. Least-squares refinement of the structure led to R factor of 0.049. The coordination sphere of rhodium and iridium can be described as a 2-legged piano-stool. All complexes are highly colored. Electrochemical studies show that 1d and 1e display quasi-reversible reduction and 1a-1c display irreversible reductions, suggesting that the acceptor orbital might be localized on the diimine ring.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.771-775
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• 1997

Treatment with electron beam irradiation was investigated for the elimination of Escherichia coli O157:H7 which has been linked to outbreaks of foodborne illness on undercooked and raw meat. Before treatment, the maximum populations were observed at 16 hr when E. coli O157:H7 was incubated in TSB at $37^{\circ}C$. Incubation at $4^{\circ}C$ did not influence survival and growth of the strain. The numbers of E. coli O157:H7 were present about $10^{7}\;CFU/mL$ in the log $(6\;hr\;at\;37^{\circ}C)$ and stationary phase $(16\;hr\;at\;37^{\circ}C)$ of cells, respectively. Freezing $(24\;hr\;at\;-18^{\circ})$ had a more marked lethal effect. The $D_{10}$ value at $-18^{\circ}C$ of E. coli O157:H7 contaminated in frozen beef was 0.45 kGy, and inactivation factor were $6.67{\sim}11.11$ at the radiation doses of $3{\sim}5\;kGy$. Therefore, electron beam irradiation was an effective method to eleminate of E. coli O157:H7.