• Journal of Environmental Science International
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• v.6 no.3
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• pp.277-283
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• 1997

SPME deuce was applied to determine the THM in an aqueous solution. The 6 kinds of THM was quantitatively detenuned by using GC-ECD which has the sample eutracted on the SPME fiber from an aqueous solution for 10 min. The THM components were well separated from $CHCl_3$ to the last $CHBr_3$ UHh 13 mons at the condition. 6 kinds of the volatile halogenated organic compounds: $CHCl_3$, $CHBrCl_2$, $CHBrtCl_2$, $CHCl_3$, $C_2Cl$. and $CHBr_3$, showed well defirled calibration graph with good llnearlty from a few ppb level up to several tens of pub concentration. $CHBr_2Cl$ and $C_2C1_4$ were detected from a few samples among the 10 of river samples. CHCl3, however, was detected In 4 sea water samples with the highest of 10 ppd among the pouuted 6 positions. Trace level of $CHBr_2Cl$ and few pub level of $CHBr_3$ were also detected at the other two sample stations. Most of the 13 rain water samples collected from 6 sampling stations were contained ppd level of $CHCl_3$, and also $CHBr_2Cl$, and C_2Cl_4$ were only detected at trace level at a few rain samples among them. We could recognize the fact that our Ut and water enoronment has already been contaminated by certain volatile halogenated organic compounds through this study.

• Journal of Environmental Science International
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• v.24 no.1
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• pp.65-71
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• 2015

This study accessed the adsorption characteristics of the 9 trihalomethanes (THMs) on coal-based granular activated carbon (GAC). The breakthrough appeared first for $CHCl_3$ and sequentially for $CHBr_2Cl$, $CHBr_3$, $CHCl_2I$, CHBrClI, $CHBr_2I$, $CHClI_2$, $CHBrI_2$, and $CHI_3$. The maximum adsorption capacity (X/M) for the 9 THMs with apparent breakthrough points ranged from $1,175{\mu}g/g$ (for $CHCl_3$) to $11,087{\mu}g/g$ (for $CHI_3$). Carbon usage rate (CUR) for $CHCl_3$ was 0.149 g/day, 5.5 times higher than for $CHCl_3$ (0.027 g/day).

• Bulletin of the Korean Chemical Society
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• v.32 no.3
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• pp.905-908
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• 2011

We report fluorescence excitation and emission spectra of the CHBr molecule generated via pyrolysis of $CH_3Br$ in a molecular beam experiment. The 193 nm attenuation cross sections were estimated from the reduction of the CHBr signal as a function of the excimer laser fluence. The derived 193 nm absorption cross section for CHBr [$(3.24{\pm}0.59){\times}10^{-17}\;cm^2$] is slightly higher than the absorption cross section previously determined for CHCl [$(2.6{\pm}0.8){\times}10^{-17}\;cm^2$], but the difference is within the estimated uncertainties in the measured cross section.

• Journal of the Korean Chemical Society
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• v.39 no.12
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• pp.918-924
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• 1995

THMs and PCBs were separated and analysed with elution on Novapak ODS or $\mu-Bondapak$ phenyl column by an eluent containing p-nitrophenol (p-NP). THMs studied were CHCl3, CHBrCl2, CHBr2Cl, and CHBr3, and PCBs used were Aroclor 1221, 1242, 1248, $\alpha-$ and $\beta-BHC.$ It was thought that the retention on the stationary phase and sensitivities of the samples are related to the interaction between the sample and stationary phase or p-NP. THMs were separated completely on the ODS column by elution with MeOH-water (30 : 70) containing $1.0{\times}10^{-4}$ M p-NP and some of PCBs were separated on the phenyl column by elution with $CH_3CN$-water(50 : 50) containing $1.0{\times}10^{-4}$ M p-NP. Detection limits of THMs were from $1.0{\times}10^{-4}$ g to $1.0{\times}10^{-6}$ g. Aroclors were $2{\times}10^{-6}$ g, and $\alpha-$ and $\beta-BHC$ were $2{\times}10^{-4}$ g and $1.0{\times}10^{-4}$ g respectively.

• Bulletin of the Korean Chemical Society
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• v.23 no.2
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• pp.291-294
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• 2002

The reactions of triplet oxygen atom with halomethanes as a potential fire extinguisher were studied by a discharge flow-chemiluminescence imaging method. The experiments were carried out under second order conditions. The bimolecular atom-molecule reaction rate constants were determined in terms of the initial rate method. The initial concentration of oxygen atom was also determined under second order rate law instead of the pseudo-first order conditions with $[O(^3P)]_0{\ll}[sample]_0$. The second order conditions were more reliable than pseudo-first order conditions for the determinations of rate constants. The rate constants of the reactions $CF_3I\;+\;O(^3P)$, $CH_3PI\;+\'O(^3P)$, and $CHBrCl_2\;+\;O(^3P)$ were determined to be $5.0\;{\times}\;10^{-12}$ , $1.1\;×\;0^{-11}$ , and $1.9\;{\times}\;10^{-14}cm^3molecule^{-1}s^{-1}$, respectively.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.360-365
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• 2012

Cascaded H-Bridge rectifier (CHBR) is a more attractive solution in traction application for its transformerless structure. Because of the currents of different cells are exactly the same one, it is a challenge job to regulate the voltages of cells with only one current controller. In this paper, a PI-based control scheme is presented to deal with the voltages balance issue in CHBR. To satisfy the demand of rectifier such as unity power factor and regulated output DC voltages, the proposed control scheme consists of two parts. One is for shaping the grid current waveform and regulating the sum of DC-link voltages of all the cells; the other one is for balancing DC-link voltages. The latter is more concerned in this paper and is discussed in detail especially. Simulations and experiments are carried on. The results verified the feasibility and effectiveness of the proposed scheme.

• Journal of Power Electronics
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• v.17 no.3
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• pp.664-673
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• 2017

With the development of multilevel converters, cascaded single-phase H-bridge rectifiers (CHBRs) has become widely adopted in high-voltage high-power applications. In this study, sequence pulse modulation (SPM) is proposed for CHBRs. SPM is designed to balance the dc-link voltage and maintain the smooth changes of switch states. In contrast to phase disposition modulation, SPM balances the dc-link voltage even after removing the load of one submodule. The operation principle of SPM is deduced, and the unbalance degree of SPM is analyzed. All the proposed approaches are experimentally verified through a prototype of a four-module (nine-level) CHBR. Conclusions are drawn in accordance with the results of SPM and its imbalance degree analysis.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.1
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• pp.121-130
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• 1996

Adsorption isotherms of three trihalomethanes(THMs: $CHCl_3$, $CHBrCl_2$ and $CHBr_2Cl$) and the other organics(p-chlorophenol and sucrose)on activated carbon fibers(ACFs) were measured. Adsorption capacities of the ACFs for these THMs were found to be comparable with or slightly larger than those of granular activated car bons(GACs) which have been widely used for trihalomethanes control in drinking water. Also, the breakthrough curve prediction was successfully carried out using a mathematical model on basis of the assumption that the adsorption equilibrium is instantaneously established when a THM solution contacts the ACF. In practice, THM removal from drinking water was investigated at water works using benchscale ACF adsorptJOn columns. The volume of water treated at a space velocity(SV) of about $100h^{-1}$ was approximately 40 l/g-ACF. The practical adsorption capacities of PCP and sucrose in column adsorption were in good agreement with those of theoretically calculated results using the batch adsorption measurments. And the saturation time model of these substrates in the columns was also agreed succesfully with practical measurments.

• Archives of Pharmacal Research
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• v.14 no.2
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• pp.188-192
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• 1991

Single non-lethal doses of chloroform $(CHCL_3)$ dichlorobromomethane $(CHCL_2Br)$, dibromochloromethane $(CHCIBr_2)$, or bromoform $(CHBr_3)$ were administered to male rats. Routes of exposure including single intraperitional (ip) and subcutaneous (sc) injection were used in order to permit comparison of severity of THM effects and renal toxicity was assessed at varied times following treatment. On an equimolar basis, sc administration of $CHBr_3$ (either 12 or 3 mmoles/kg) is more effective at increasing KW/BW than ip $CHCI_3$ treatment. Plasma urea nitrogen (BUN) following ip THM injections are markedly increased with all four THM at 24 hours post treatment. BUN response to $CHCL_2Br$ and $CHCIBr_3$-effected BUN levels have essentially returned to those of vehicle control. THM sc treatment results in a BUN response similar to that seen following ip treatment, with only the time course being different. With the exception of $CHCL_3$, sc and ip-treatments appear to be equally effective in evoking absolute BUN elevations. These results suggest that THM administration induce renal toxicity dependent upon the route or exposure.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.426-432
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• 2013

The mechanisms concerning C-Cl activation of $CCl_4$ by $CHBr^{{\cdot}-}$ and $CBr{_2}^{{\cdot}-}$ have been comparatively investigated in theory. Optimized geometries and frequencies of all stationary points on PES are obtained at the BhandHLYP/aug-cc-pVTZ level of theory, and then the energy profiles are refined at the QCISD(T) method with the aug-cc-pVTZ basis by using the BhandHLYP/aug-cc-pVTZ optimized geometries. Our calculated findings suggest that in the title reactions the major mechanisms consist of both Cl-abstraction and $S_N2$ substitution reactions. Also, a succeeding pathway described by electron transfer was revealed before the initial Cl-abstraction products separate. Those are consistent with relevant experimental results.