• Journal of the Korean Society of Combustion
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• v.4 no.1
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• pp.27-38
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• 1999

We constructed a wire-cylinder type pulsed corona discharge system for $NO_x$ removal, which was operated in room temperature. A emission spectrometer was built with a boxcar averager and monochrometer equipped with photo-multiplier tube detector. The sensitivity of the emission spectrometer was greatly improved by synchronizing the emission spectrometer with pulsed corona discharge system using a triggered spark-gap switch. $N_2$ spectrum($c^3{\Pi}_u{\rightarrow}X^1{\Sigma}_g{^+}$) was measured in the range of 300 - 450 nm and oxidizing OH radical emission($A^2{\Sigma}^+{\rightarrow}X^2{\Pi}$) was measured in case $N_2$ was supplied with water bubbling. As wet gas composition of inlet $N_2$ supplied in the discharge system increased, the intensity of OH emission was increased and saturated at wet gas composition 50%. We also investigated additive effect of $C_2H_4,\;H_2O,\;H_2O_2$ on the intensity of OR emission and $NO/NO_2/NO_x$ reduction and analysed the related reaction mechanism in corona discharge process. $H_2O_2$ additive increased the intensity of OH emission and $NO/NO_x$ reduction.

• Nuclear Engineering and Technology
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• v.54 no.2
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• pp.486-492
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• 2022

Nitrogen oxides (NO_x; NO and NO₂) are major air pollutants and can cause harmful effects on the human body. Electron Beam Flue Gas Treatment (EBFGT) is a technology that generates electrons with an energy of 0.5-1 MeV using electron accelerators and effectively processes exhaust gases. In this study, NO_x was removed using an electron beam accelerator with spraying additives (NaOH and NH₄OH). NO and NO₂ were 100% and more than 94% removed, respectively, at an electron beam absorbed dose of 20 kGy and an additive concentration of 0.02 M (mol/L). In most cases, NO_x was removed better with lower initial NOx concentrations and higher electron beam absorbed doses. As the irradiation strength (mA) of the electron beam increases, the probability of electron impact on the material accordingly rises, which may lead to increase removal efficiency. The results of the present study show that the continuous electron beam process using additives achieved more effective removal efficiency than either individual process (wet-scrubbing or EB irradiation only).

• Journal of the Korea Safety Management & Science
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• v.13 no.3
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• pp.55-61
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• 2011

Unit cost for asbestos removal work which have been made out at government contract award for recent three years has been reviewed and shown with table. And the cost have been compared with ones made out by two agencies, American asbestos removal specialists, government ministry for making out comparison tables. First, legal and practical work status survey have been made to determine reasonability of introducing separate contract-awarding system, as a part of ensuring reasonable unit work cost. And then, two different status have been compared and there in introduction possibility of separate contract-awarding system, it is found out. In interior removal work case, it is thought that 50% by owner, 60% unit work cost by the expert of which removal specialist think as reasonable unit cost. the results for exterior and spray work method are shown with almost same context. Impact factors for determining unit work cost such as project mount, project kind, contract-awarding method, subcontract method have been compared with parties. Removal specialist and expert group have almost same ideas for project amount which has been hightestly weighed but owner's recognition has partially lower than specialists idea. There are almost no difference of recognition between three(3) parties for project kind. Idea comparison of reasonable unit work cost for asbestos removal work between three concerned parties has been analyzed and found out that expert group do unit work cost, 65% of which removal specialists estimate, in interior tex removal. And there is almost no difference between them in exterior roof slate removal. But there is considerable difference between them that owner estimates 50% unit cost of specialist one while expert group estimate 50% of specialist idea of unit removal cost.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.1
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• pp.19-25
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• 2018

The objectives of this study were to evaluate the removal characteristics of total nitrogen, the influence factor of denitrification and the optimum operating condition in the pigment wastewater treatment using PAC-A/O process. The operating conditions of PAC-A/O process were mean BOD volumetric loading $0.86kgBOD/m^3/day$, mean F/M ratio 0.072~0.13 kgBOD/kgMLVSS/day and mean C/N ratio 3.47, respectively. The conditions of anoxic process in the field plant test were mean pH 8.3~8.7 and mean temperature $34.1{\sim}44.0^{\circ}C$. The ORP bending point knee was eventually appeared in the ORP -107 mV and $NO_3{^-}-N$ removal efficiency was increased according to the ORP decrease. In the ORP -107 mV below condition, the removal efficiency of T-N and $NO_3{^-}-N$ was 92.3~95.0% and 98.5~99.7%. Denitrification rate was calculated to be 1.581~1.791 mg $NO_3{^-}-N/gMLSS/hr$. The experimental results showed that the ORP control in the PAC-A/O process could be an effective method for treatment of pigment wastewater.

• Carbon letters
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• v.7 no.2
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• pp.105-113
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• 2006

The electro-chemical removal (ECR) of water pollutants by metal-ACF electrodes from wastewater was investigated over wide range of ECR time. The ECR capacities of metallic ACF electrodes were related to physical properties such as adsorption isotherm, surface area and pore size and to reaction time. Surface morphologies and elemental analysis for the metal supported ACFs after electro-catalytic reaction were investigated by scanning electron microscopy (SEM) and energy disperse X-ray (EDX) to explain the changes in adsorption properties. The IR spectra of metallic ACFs for the investigation of functional groups show that the electro-catalytic treatment is consequently associated with the removal of pollutants with the increasing surface reactivity of the activated carbon fibers. The metal-ACFs were electro-catalytically reacted to waste water to investigate the removal efficiency for the COD, T-N, $NH_4$-N, $NO_3$-N and $NO_2$-N. From these removal results of the piggery waste using metallic ACFs substrate, satisfactory removal performance was achieved. The removal efficiency of the metallic ACFs substrate was mainly determined by the properties of the material for adsorption and trapping of organics, and catalytic effects.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.139-140
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• 2020

LEFC, a emotional concrete and one of light-transmitting concrete, has a characteristic of transmitting light, so its utility is great. In this study, in order to utilize LEFC under ultraviolet conditions, GST, a low-cost high-performance photocatalyst, was incorporated into the UHPC mix proportion. Specimens were prepared by applying ISO 22197-1. The test was conducted according to the standard and it was confirmed that the NO removal performance was over 50%.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.2050-2052
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• 2000

In this paper, the effect of $O_2$ concentration on NO removal and $NO_2$ generation by corona discharge from simulated flue gas was measured and estimated for the wire-plate reactor. $NO_2$ removal rate was 0$\sim$30[%] under about 3.4[%] of oxygen concentration, however, it was difficult to remove NOx over 3.4[%] of oxygen concentration. It may be due to generate $NO_2$ from $N_2$ and $O_2$ molecules and converse NO to $NO_2$ by 0 and $O_3$. Magnetic field applied to electric field in plasma was very effective for NOx removal under 2[%] of $O_2$ concentration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.5
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• pp.451-457
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• 2000

Experimental investigations on the effect of two kinds of additives ; aqueous NaOH solution and ammonia(NH$_3$) for removal of NOx and SO$_2$ simultaneously by corona discharge were carried out. The simulated combustion flue gas was[NO(0.02[%])-SO$_2$(0.08[%])-$CO_2$-Air-$N_2$] Volume percentage of aqueous NaOH solution used was 20[%] and $N_2$flow rate was 2.5[$\ell$/min] for bubbling aqueous NaOH solution Ammonia gas(14.81[%]) balanced by argon was diluted by air. NH$_3$ molecular ratios(MR) based on [NH$_3$] and [NO+SO$_2$] were 1, 1.5 and 2.5 The vapour of aqueous NaOH solution and NH$_3$was introduced to the main simulated combustion flue gas duct through injection systems which were located at downstream of corona discharge reactor. NOx(NO+NO$_2$) removal rate by injecting the vapour of aqueous NaOH solution was much better than that by injecting NH$_3$however SO$_2$removal rate by injecting NH$_3$was much better than that by injecting the vapour of aqueous NaOH SO$_2$removal rate slightly increased with increasing applied voltage. When the vapour of aqueous NaOH solution and NH$_3$were simultaneously injection NOx and SO$_2$ removal rate were significantly increased.

• Journal of Environmental Health Sciences
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• v.23 no.1
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• pp.105-108
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• 1997

For the removal of heavy metals, Cd, Cu and Cr were used. The initial concentration of Cd and Cu were 1-10 ppm, the removal efficiency of Cd and Cu was 76.2-89.0% and 69.0-79.0%, respectively. The initial concentration of Cr were 1~5 ppm, and the-removal efficiency was low especially at high concentration. In general, the initial concentrations of heavy metals had no relation to the removal efficiency. At the beginning, the removal efficiency was very high, but it was maintained at constant concentration. The trends of accumulations of heavy metals in the stem increased in proportion to the initial concentration. The removal efficiency of heavy metals increased a little bit when nutrients existed in the solution. So that, the initial concentration of Cd and Cu were 1-10 ppm, the removal efficiency of Cd and Cu was 84.8-91.0% and 75.9-82.0%. The initial concentration of Cr were 1-5 ppm, the removal efficiency was 25.0-67.0%.

• Korean Journal of Materials Research
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• v.18 no.6
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• pp.334-338
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• 2008

The purpose of this study is to characterize various electrolytes on electrochemical mechanical planarization (ECMP). The ECMP system was modified from conventional CMP system to measure the potentiodynamic curve and removal rate of Cu. The potentiodynamic curves were measured in static and dynamic states in investigated electrolytes using a potentiostat for the evaluation of the polishing behavior on ECMP. KOH (alkaline) and $NaNO_3$ (salt) were selected as electrolytes which have high conductivity. In static and dynamic states, the corrosion potential decreased and the corrosion current increased as a function of the electrolyte concentration. But, the electrochemical reaction was prevented by mechanical polishing effect in the dynamic state. The static etch and removal rate were measured as functions of concentration and applied voltage. When $NaNO_3$ was used, the dissolution was much faster than that of KOH. It was concluded that the removal rate was strongly depended on electrochemical dissolution. The removal rate increased up to 350 nm/min in $NaNO_3$ based electrolyte.