• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.1
• /
• pp.83-96
• /
• 2005

The purposes of this study were to characterize the local levels of VOCs (volatile organic compounds), to develop source profiles of VOCs, and to quantify the source contribution of VOCs using the CMB (chemical mass balance) model. The concentration of VOCs had been measured every 6-day duration in the SRO monitoring site in the Yeosu Petrochemical Industrial Complex from September 2000 to August 2002. The total of 35 target VOCs, which were included in the TO-14 designated from the U.S. EPA, was selected to be monitored in the study area. During a 24-h period, the ambient VOCs were sampled by using canisters placing about 10 ～ 15 m above the ground level. The collected canisters were then analyzed by a GC-MS in the laboratory. Aside from ambient sampling at the SRO site, the VOCs had been intensively and massively measured from 8 direct sources and 4 general sources in the study area. The results obtained in the study were as follows; first, the annual mean concentrations of the target VOCs were widely distributed regardless of monitoring sites in the Yeosu Petrochemical Industrial Complex. In particular, the concentrations of BTX (Benzene, Toluene, Xylene), vinyl chloride were higher than other target compounds. Second, based on these source sample data, source profiles for VOCs were developed to apply a receptor model, the CMB model. Third, the results of source apportionment study for the VOCs in the SRO Site were as follows; The source of petrochemical plant was apportioned by 31.3% in terms of VOCs mass. The site was also affected by 16.7% from wastewater treatment plant, 14.0% from iron mills, 8.4% from refineries, 4.4% from oil storage, 3.8% from automobiles, 2.3% from fertilizer, 2.3% from painting, 2.2% from waste incinerator, 0.6% from graphic art, and 0.4% from gasoline vapor sources.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.E3
• /
• pp.75-85
• /
• 2005

A mathematical sensitivity analysis of the flow-through dynamic flux chamber technique, which has been utilized usually for various trace gas flux measurement from soil and water surface, was performed in an effort to provide physical and mathematical understandings of parameters essential for the NO flux calculation. The mass balance equation including chemical reactions was analytically solved for the soil NO flux under the steady state condition. The equilibrium concentration inside the chamber, $C_{eq}$, was found to be determined mainly by the balance between the soil flux and dilution of the gas concentration inside the chamber by introducing the ambient air. Surface deposition NO occurs inside the chamber when the $C_{eq}$ is greater than the ambient NO concentration ($C_{0}$) introducing to the chamber; NO emission from the soil occurs when the $C_{eq}$ is less than the ambient NO concentration. A sensitivity analysis of the significance of the chemical reactions of NO with the reactive species (i.e. $HO_{2},/CH_{3}O_{2},/O_{3}$) on the NO flux from soils was performed. The result of the analysis suggests that the NO flux calculated in the absence of chemical reactions and wall loss could be in error ranges from 40 to $85\%$ to the total flux.

• Bulletin of the Korean Chemical Society
• /
• v.30 no.10
• /
• pp.2203-2207
• /
• 2009

Chemical equilbria of nickel chloride in HCl solution at $25\;{^{\circ}C}$ were analyzed by considering chemical equilibria, mass and charge balance equations. The activity coefficients of solutes were calculated by using Bromley equation. The necessary thermodynamic properties, such as the equilibrium constant for the formation of Ni$Cl^+$ at zero ionic strength and interaction parameter, were evaluated by applying Bromley equation to the stability constant data reported in the literature. It was found that most nickel exists as $Ni^{2+}$ in HCl solution up to 5 molality HCl. The pH values of Ni$Cl_2-HCl-H_2O$ system at $25\;{^{\circ}C}$ calculated in this study agreed well with the pH values measured by employing pH meter.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.23 no.5
• /
• pp.670-677
• /
• 1999

An analysis of generation and growth of multicomponent particles has been carried out to predict the size and composition distributions of particles generated in the Modified Chemical Vapor Deposition(MCVD) process. In MCVD process. scale-up of sintering and micro-control of refractive index may need the Information about the size and composition distributions of $SiO_2-GeO_2$ particles that are generated and deposited. The present work solved coupled steady equations (axi-symmetric two dimensions) for mass conservation, momentum balance. energy and species(such as $SiCl_4$, $GeCl_4$, $O_2$, $Cl_2$) conservations describing fluid flow. heat and mass transfer in a tube. Sectional method has been applied to obtain multi-modal distributions of multicomponent aerosols which vary in both radial and axial directions. Chemical reactions of $SiCl_4$ and $GeCl_4$ were included and the effects of variable properties have also been considered.

• Journal of Environmental Health Sciences
• /
• v.36 no.1
• /
• pp.61-71
• /
• 2010

Intensive measurements of airborne respirable $PM_{2.5}$ and inhalable $PM_{2.5}$ were conducted in the downtown area of Iksan city. The $PM_{2.5}$ and $PM_{2.5}$ samples were collected twice a day in the Iksan city of Korea from October 17 to November 1, 2004. The purpose of the study was to determine the inorganic water-soluble components and trace elements of $PM_{2.5}$ and $PM_{2.5}$ in the atmospheric environment and estimate the contribution rate of major chemical components from a mass balance of all measured particulate species. The chemical analysis for PM samples was conducted for water-soluble inorganic ions using ion chromatography and trace elements using PIXE analysis. The mean concentrations of respirable $PM_{2.5}$ and inhalable $PM_{2.5}$ were $51.4{\pm}29.7$ and $79.5{\pm}39.6\;{\mu}g/m^3$, respectively, and the ratio was 0.62. The ion species of $NO_3$, $SO_4^2$, and $NH_4^+$ were abundant in both $PM_{2.5}$ and $PM_{2.5}$. These components predominated in respirable $PM_{2.5}$ fraction, while $Na^+$, $Mg^{2+}$, $Ca^{2+}$ mostly existed in coarse particle mode. Elemental components of S, Cl, K, and Si were abundant in both $PM_{2.5}$ and $PM_{2.5}$. These elements, except for Si, were considered to be emitted from anthropogenic sources, while Si, Al, Fe, Ca existed mainly in coarse particle mode and were considered to be emitted from crustal materials. The averaged mass balance analysis showed that ammonium nitrate, ammonium sulfate, crustal component, and other trace elements were composed of 18.4%, 13.2%, 4.8%, 3.5% for PM2.5 and 17.0%, 11.6%, 13.7%, 4.4% for $PM_{2.5}$, respectively.

• Membrane Journal
• /
• v.21 no.3
• /
• pp.236-246
• /
• 2011

In this study, we used prepared a cylindrical module consisting 100 hollow fibers of commercialized (hydrophobic) polyethylene membrane of $0.4{\mu}m$ pore size and systematically studied performance of direct contact membrane distillation (DCMD) and sweep gas membrane distillation (SGMD) in terms of variation of permeate flux and salt rejection with respect to temperature drop across the membrane, salt concentrations in feed, and flow rates of cooling water and sweep gas. SGMD was regarded as DCMD with a sweep gas layer between permeate-side membrane surface and cooling water. Sweep gas flow decreases the permeate flux from that of DCMD by providing an additional gas-layer resistance. We compared DCMD and SGMD performance by using mass balance with a fitting parameter (${\omega}$), indicating fraction of permeate flow rate.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.2
• /
• pp.231-239
• /
• 2000

This study was investigated to estimate optimal conditions and biological oxic denitrification to treat wastewater with low C/N ratio and high strength total inorganic nitrogen (TIN) concentration by using $A_2O$ fixed biofilm system. The lab-scale experimental system packed with media, which were composed of polyvinylidene chloride fiber (oxic basin) and ceramic ball (anaerobic and anoxic basin), was used. This system was operated with various influent alkalinities at the C/N(TOC/TIN) ratio of 0.5. The study results showed that TOC were removed over 96.0% at all operation conditions. The removal efficiencies over 93.5% for $NH_4{^+}-N$ and 81.8% for TIN were obtained at the alkalinity of about 1210mg/L(Run 5). Among the removal of TIN, 64.9% was occurred by biological denitrification at an oxic basin. It was confirmed through mass balance of alkalinity and nitrogen that the amount of alkalinity produced during biological denitrification at oxic basin was 2.49~3.46 mg Alkalinity/mg $NO_2{^-}-N$, ${\Delta}TOC/{\Delta}DEN$ of 0.34 (Run 5) was obtained at an oxic basin, which was less than the theoretical value of 1.22.

• Journal of Korean Society on Water Environment
• /
• v.23 no.5
• /
• pp.607-612
• /
• 2007

In this study, we investigated the variations of the kinetic coefficients and Chemical Oxygen Demand (COD), N and P mass used for assimilation of a sequencing batch reactor (SBR) system with the variation of SRTs; SRTs of 7.5, 10.0, 12.5, 15.0 and 20.0 days were tested in one cycle of SBR operation to determine the optimum conditions for the operation of the SBR and estimate its COD, nitrogen and phosphorus removal efficiencies. The SBR system was operated under the conditions as follows: an operation time of 6 hours per cycle, a hydraulic retention time (HRT) of 12 hours, an influent COD loading of $0.4kg/m^3/day$, and an influent nitrogen loading of $0.068kgT-N/m^3/day$. The yield coefficient (Y) and decay rate coefficient ($k_d$) were estimated to be 0.4198 kgMLVSS/kgCOD and $0.0107day^{-1}$ by calculating the removal rate of substrate according to the variation of SRT. Considering total nitrogen amount removed by sludge waste process, eliminated by denitrification, and in clarified water effluent with reference to 150 mg/cycle of influent nitrogen amount, the percentage of nitrogen mass balance from the ratio of the nitrogen amount in effluent (N output) to that in influent (N input) for Runs 1~5 were 95.5, 97.0, 95.5, 99.5, and 95.5%, respectively, which is well accounted for, with mass balances close to 100%.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.7
• /
• pp.1920-1926
• /
• 2010

Yoon et $al.^1$ presented an approximate mathmatical model to describe ammonia removal from an experimental batch reactor system with gaseous headspace. The development of the model was initially based on assuming instantaneous equilibrium between ammonia in the aqueous and gas phases. In the model, a "saturation factor, $\beta$" was defined as a constant and used to check whether the equilibrium assumption was appropriate. The authors used the trends established by the estimated $\beta$ values to conclude that the equilibrium assumption was not valid. The authors presented valuable experimental results obtained using a carefully designed system and the model used to analyze the results accounted for the following effects: speciation of ammonia between $NH_3$ and $NH^+_4$ as a function of pH; temperature dependence of the reactions constants; and air flow rate. In this article, an alternative model based on the exact solution of the governing mass-balance differential equations was developed and used to describe ammonia removal without relying on the use of the saturation factor. The modified model was also extended to mathematically describe the pH dependence of the ammonia removal rate, in addition to accounting for the speciation of ammonia, temperature dependence of reactions constants, and air flow rate. The modified model was used to extend the analysis of the original experimental data presented by Yoon et $al.^1$ and the results matched the theory in an excellent manner.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2004.09a
• /
• pp.334-337
• /
• 2004

Groundwater chemistry in Namwon area, Korea, was investigated to understand the contribution of geochemical processes on groundwater chemistry. For this study, a total of 279 groundwater samples were collected from 93 wells distributed over the study area. Higher concentrations of major ions are generally encountered in the shallow alluvial wells, suggesting that these chemicals are originated from the surface contamination sources. Mass balance analysis based on reaction stoichiometry reveals that the water chemistry is regulated by three major chemical processes: weathering of silicate/ carbonate minerals, input of C1/SO$_4$ salts, and nitrate generating processes. The results show that mineral weathering is the most dominating factor regulating the groundwater chemistry. However, the groundwaters with the higher salt concentration indicate the larger mineral weathering effect, suggesting that some part of the mineral weathering effect is also associated with the anthropogenic activities such as limes applied to the cultivated lands, carbonates (CaCO$_3$) in the cement materials.