• Journal of Korean Society for Atmospheric Environment
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• v.21 no.3
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• pp.285-293
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• 2005

This study was aimed at estimation of gas-particle partitioning of polychlorinated biphenyls (PCBs) in ambient air. The samples were collected at urban site in Japan from March 2002 to January 2003. The concentration of total PCBs (from 4 CB to 10 CB) and TEQ (Toxic equivalent) ranged from 62 to $247\;pg/m^3$ and from 2 to $14\;fgTEQ/m^3 $, respectively. The average contribution $(\%)$ of gas phase to total PCBs concentration was above $80\%$, which suggests that in the atmosphere PCBs predominantly existed in the gas phase. The weak correlations between total PCBs concentration and temperature was found. However this result was due to a typhoon during summer and raining during sampling period. The gas-particle partition coefficient (Kp) was obtained as a function of temperature. The partition ratio of gaseous and particulate phase PCBs can be estimated for an arbitrary temperature. The plot of gas/particle partition coefficient (log Kp) vs. sub-cooled liquid vapor pressure $(log\;P_L)$ had reasonable correlations for individual samples but the slope varied among the samples (coefficients of determination for log Kp versus log $P_L$ plot were> 0.76 $(p<0.0001)$, except for 3 samples). As a result, the variations in the slope among the sampling period may be due to change of temperature, raining during sampling period and wind in this study.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.997-1002
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• 2022

Oxyapatite[Ca₂Nd₈(SiO₄)₆O₂] glass-ceramics have been suggested as wasteforms for the immobilisation of rare-earth radioactive nuclides because of their high waste-loading capability and good chemical durability. In particular, a partitioning effect is predicted to contribute to an enhancement of corrosion resistance in glass-ceramics compared with that of conjugate glasses of the same composition. Because rare-earths are inherently insoluble nuclides, detection of changes in corrosion behavior between glass-ceramics and conjugate glasses under normal conditions is not easy. In this study, therefore, we revealed the partitioning effect by exposing glass-ceramics and glasses to solution of pH 2, 7 and 10 at 90 ℃ for 20 d. In addition, we proposed the corrosion mechanism for oxyapatite glass-ceramics under various corrosion conditions. Especially, the glassy phase dissolved first, followed by the oxyapatite phase during pH 7 corrosion.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.115-115
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• 2020

Water network partitioning (WNP) is an initiative technique to divide the original water distribution network (WDN) into several sub-networks with only sparse connections between them called, District Metered Areas (DMAs). Operating and managing (O&M) WDN through DMAs is bringing many advantages, such as quantification and detection of water leakage, uniform pressure management, isolation from chemical contamination. The research of WNP recently has been highlighted by applying different methods for dividing a network into a specified number of DMAs. However, it is an open question on how to determine the optimal number of DMAs for a given network. In this study, we present a method to divide an original WDN into DMAs (called Clustering) based on community structure algorithm for auto-creation of suitable DMAs. To that aim, many hydraulic properties are taken into consideration to form the appropriate DMAs, in which each DMA is controlled as uniform as possible in terms of pressure, elevation, and water demand. In a second phase, called Sectorization, the flow meters and control valves are optimally placed to divide the DMAs, while minimizing the pressure reduction. To comprehensively evaluate the WNP performance and determine optimal number of DMAs for given WDN, we apply the framework of multiple-criteria decision analysis. The proposed method is demonstrated using a real-life benchmark network and obtained permissible results. The approach is a decision-support scheme for water utilities to make optimal decisions when designing the DMAs of their WDNs.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.12
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• pp.1270-1276
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• 2005

When gas/particle partitioning of PAHs in the atmosphere approached an equilibrium state, the slope of linear regression between gas/particle partitioning coefficient($logK_p$) and subcooled liquid vapour pressure($logP_L^O$) was -1. But it was alleged that the slope of equilibrium state might not be -1 in real atmospheric environment due to heterogeneous characteristics of particulate matter. In This study, it would be found if gas/particle partitioning of PAHs segregated with particle size in equilibrium state was based on the hypothesis mentioned above. We have calculated the slopes of $logK_p$ v.s. $logP_L^O$ after collecting 10 set samples which consisted of particulate and vaporous phases. The slope was close to -1 in equilibrium states. But despite of equilibrium state, all slopes segregated with particle size were not close to -1 and those were gentler with larger particle size. The difference of slopes in equilibrium states was almost against the assumption of gas/particle partitioning theory. When the gas/particle partitioning was due to adsorption, the desorption enthalpy was different in each particle size. When it was absorption, the activity coefficient was different. The difference of desorption enthalpy and activity coefficient in each particle size indicate the heterogeneous characteristics of the bulk particle. This may be the reason for slope variation with particle size even though in an equilibrium state.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1123-1127
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• 2012

P-gp (P-glycoprotein) is a member of the ATP binding cassette (ABC) family of transporters. It transports many kinds of anticancer drugs out of the cell. It plays a major role as a cause of multidrug resistance (MDR). MDR function may be a cause of the failure of chemotherapy in cancer and influence pharmacokinetic properties of many drugs. Hence classification of candidate drugs as substrates or nonsubstrate of the P-gp is important in drug development. Therefore to identify whether a compound is a P-gp substrate or not, in silico method is promising. Recursive Partitioning (RP) method was explored for prediction of P-gp substrate. A set of 261 compounds, including 146 substrates and 115 nonsubstrates of P-gp, was used to training and validation. Using molecular descriptors that we can interpret their own meaning, we have established two models for prediction of P-gp substrates. In the first model, we chose only 6 descriptors which have simple physical meaning. In the training set, the overall predictability of our model is 78.95%. In case of test set, overall predictability is 69.23%. Second model with 2D and 3D descriptors shows a little better predictability (overall predictability of training set is 79.29%, test set is 79.37%), the second model with 2D and 3D descriptors shows better discriminating power than first model with only 2D descriptors. This approach will be used to reduce the number of compounds required to be run in the P-gp efflux assay.

• Journal of the Korean Chemical Society
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• v.11 no.2
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• pp.77-80
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• 1967

Radiolysis of polyacrylonitrile(PAN) has been studied. Parameters for crosslinking and scission induced by gamma-ray irradiation were obtained by means of sol-gel partitioning method. G-value of crosslinking in PAN ($\bar{M}n=6{\times}10^5$) was 0.038 and the gel dose 21.6 Mrad. The effects of irradiation on the thermal degradation rate in PAN was also studied. No appreciable changes in thermal degradation rate observed up to 81.8 Mrad of irradiation dose.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.133-142
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• 2007

As the environmental pollution caused by excessive uses of chemical fertilizers and pesticides is aggravated, organic farming using pasture and livestock manure is gaining an increased necessity. The application rate of the organic farming materials to the field is determined as a function of crops and soil types, weather and cultivation surroundings. When livestock manure is used for organic farming materials, the volatilization of ammonia from field-spread animal manure is a major source of atmospheric pollution and leads to a significant reduction in the fertilizer value of the manure. Therefore, an ammonia emission model should be presented to reduce the ammonia emission and to know appropriate application rate of manure. In this study, the ammonia emission rate from field-applied pig manure is predicted using an artificial neural network (ANN) method, where the Michaelis-Menten equation is employed for the ammonia emission rate model. Two model parameters (total loss of ammonia emission rate and time to reach the half of the total emission rate) of the model are predicted using a feedforward-backpropagation ANN on the basis of the ALFAM (Ammonia Loss from Field-applied Animal Manure) database in Europe. The relative importance among 15 input variables influencing ammonia loss is identified using the weight partitioning method. As a result, the ammonia emission is influenced mush by the weather and the manure state.

• Nuclear Engineering and Technology
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• v.42 no.4
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• pp.394-413
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• 2010

The object of this paper is to identify the key elements that impact a radiation dose at EAB (Exclusion Area Boundary). This study is based on the AST (Alternative Source Terms) as defined in Regulatory Guide 1.183. The LOCA (Loss of Coolant Accident) and the LRA (Locked Rotor Accident) are selected as limiting cases. A sensitivity analysis of accidental behavior with respect to various parameters during LOCA and LRA at Kori Unit 1 is also undertaken for the following objectives: to determine the limiting parameters, to find the impact trend of the radiation dose, and to find the safety margin between AST and TID (Technical Information Document) methodologies. This work confirms that key parameters are particulate removal rate, decontamination factor, iodine chemical form, gap fraction, partitioning factor, and the impact of isotopes group. Comparing TID with AST, the radiation dose of TID is about 80% greater than that of AST under a LOCA, and about 60% greater than that of AST for the case of a LRA; thus the safety margin is remarkably increased when the AST is used. In this work, the sensitivity analysis results are presented in terms of a sensitivity index called the "NDD (Normalized Dose Difference)", which compares the impact of parameters with that of a reference case. These values are derived by using a combination of the leak rate (primary to secondary), iodine chemical form, gap fraction, partitioning factor, spray removal rate, source term, and other variables.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.226-233
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• 2007

In this study, the effects of additives such as ionic surfactant and cosurfactant were studied on the solubilization of sulfur compounds contained in the crude oil by Tergitol series nonionic surfactants. It was found that the addition of an ionic surfactant such as sodium oleate, potassium oleate, CTAB and DTAB did not enhance solubilization capacity of Tergitol series nonionic surfactant. On the other hand, the addition of a long-chain alcohol as a cosurfactant increased the solubilization of sulfur compounds in the crude oil. The effect of alcohol was found to become reduced with an increase in the amount of crude oil used mainly due to partitioning phenomena of an nonionic surfactant. The enhancement of solubilizing capacity of Tergitol series nonionic surfactant with addition of a cosurfactant was associated with a decrease in interfacial tension between crude oil and surfactant solution. The pH of Tergitol nonionic surfactant solution did not affect the solubilization of sulfur compounds. Finally, it was found that the growth of sulfur reducing microoganisms was not greatly affected by both addition of nonionic surfactant and cosurfactant.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.206.2-206.2
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• 2003

In continuing search for bioactive compounds from Korean marine algae, we found cholinesterase-inhibitory activity in the methanolic extract of brown alga Sargassum sagamianum. After partitioning between CHCl$_3$ and 30% MeOH, the former layer was purified by a series of ODS flash, silica column, gel-filtration on Sephadex LH-20, and HPLC to give two farnesylacetone derivatives. Their structures were identified by comparison with the literature data. Compounds 1 and 2 showed moderate acetylcholinesterase and butyrylcholinesterase inhibitory activities with IC$\sub$50/ values of 65.0∼48.0 ${\mu}$M and 34.0∼23.0 ${\mu}$M, respectively. (omitted)