• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.28-32
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• 1998

Two organophosphorous insecticides, Dichlorovos and Chloropyrifos were degraded in the presence of UV irradiation, UV irradiation with $TiO_2$ powder and UV irradiation with sea sand using low pressure mercury lamp. The identification of these compounds was carried out by gas chromatograph with a nitrogen-phosphorous detector, Total Organic Carbon and Ion Chromatograph, respectively. Both dichlorvos and chloropyrifos, UV irradiation with sea sand were more degradable than UV irradiation and UV irradiation with $TiO_2$ powder. The final products were $Cl^-$ in Dichlorvos, $Cl^-$ $SO_4{^{2-}}$ in Chloropyrifos, respectively.

• Journal of the Korean Operations Research and Management Science Society
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• v.31 no.3
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• pp.63-79
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• 2006

In this study we consider a CONWIP system in which the processing times at each station follow a Coxian distribution and the demands for the finished products arrive according to a compound Poisson process. The demands that are not satisfied immediately are either backordered or lost according to the number of demands that exist at their arrival Instants. For this system we develop an approximation method to calculate performance measures such as steady state probabilities of the number of parts at each station, proportion of lost demands and the mean number of backordered demands. For the analysis of the proposed CONWIP system, we model the CONWIP system as a closed queueing network with a synchronization station and analyze the closed queueing network using a product-form approximation method. A recursive technique is used to solve the subnetwork in the application of the product-form approximation method. To test the accuracy of the approximation method, the results obtained from the approximation method are compared with those obtained by simulation. Comparisons with simulation show that the approximation method provides fairly good results.

• Economic and Environmental Geology
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• v.14 no.3
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• pp.123-142
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• 1981

Granitic complex in the Woosanbong area is composed of schistose granite, two-mica granite, biotite granite, porphyritic granite and pink feldspar granite in order of intrusion. In their boundary aspects, the gradational change between porphyritic granite and pink feldspar granite is observed in field relations. All the granites of the complex are classified to quartz monzonite by the modal compositions following Bateman's classification (1961) with the exception of pink feldspar granite which belongs to granite according to the petrographical classification. The first three granites are characterized by highly development of vein and/or lens-like pegmatites in their bodies, and two others contain green hornblende uniquely. These leucocratic two-mica granite shows an unusual character in ratio of muscovite to biotite 1: 0.7 to 1:13, and contains dominantly microcline. The content of muscovite varies in places in the field. Under the polarizing microscope it is revealed that the muscovite flakes occur as the products altered from biotite partly or completely, and it usually associates with chlorite flakes nearby. These features, therefore, suggests that biotite probably has been altered to muscovite and chlorite by hydration during deuteric processes. At the same stage, sericitization of plagioclase by the hydrolytic decomposition, and transformation of orthoclase to microcline may be taken place. Accordingly, it is obviously permissible to consider the two-mica granite as a kind of 'apo-granite' by deuteric alterations during the consolidation of magma.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.2
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• pp.149-159
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• 2002

The objective of this study was to evaluate the formation characteristics of CBs and CPs from TCE, aliphatic compound. The experiment was carried out in a fixed reactor during 30 min under the oxidation condition at the range of temperature, 300~$700^{\circ}C$. MSWI fly ash was used as catalyst in this study. Total amount of CBs formed greater magnitude than that of CPs overall range of reaction temperature. It is proposed that the formation of CPs was caused from hydroxylation of CBs. According to increasing temperature to $600^{\circ}C$, the yield of CBs and CPs increased but significantly decreased at $700^{\circ}C$. It is suggested that decomposition rate was faster than formation rate at the high temperature. In the homologue distribution of CBs, DCBs were major products at 30$0^{\circ}C$ and the amount of higher chlorinated compound increased to $600^{\circ}C$. Because they were formed by chlorination of lower chlorinated compounds. In case of CPs, the amount of DCPs was 90% of total amounts in both thermal formation and catalytic reaction. On the other hand it was clearly observed that the chlorination rate in catalytic reaction was higher than in thermal formation with TCE only.

• Asian Journal of Atmospheric Environment
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• v.4 no.2
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• pp.63-71
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• 2010

The removal characteristics for aromatic and aliphatic VOCs by electron beam (EB) were discussed in terms of several removal variables such as initial VOC concentration, absorbed dose, background gas, moisture content, reactor material and inlet temperature. It was reviewed that only reactor material was an independent variable among the potential control factors concerned. It was also suggested that main mechanism by EB should be radical reaction for the VOC removal rather than that by primary electrons. It was discussed that the removal efficiency of benzene was lower than that of hexane due to a closed benzene ring. In the case of aromatic VOCs, it was observed that the decomposition of the VOCs with more functional groups attached on the benzene ring was much easier than those with less ones. As for aliphatic VOCs, it was also implied that the longer carbon chain was, the higher the removal efficiency became. An EB-catalyst hybrid system was discussed as an alternative way to remove VOCs more effectively than EB-only system due to much less by-products. This hybrid included supporting materials such as cordierite, Y-zeolite, and $\gamma$-alumina.

• Journal of the Korean Magnetic Resonance Society
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• v.6 no.1
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• pp.78-83
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• 2002

A new fluoroquinolone (DW-116) with a broad antibacterial spectrum was synthesized by introducing functional fluoropyridyl and methylpyrazine groups on N1, C7 position of quinolone moiety, respectively. $^{1}$H and $^{13}$ C NMR signal assignments and structure were completely elucidated by 2D-NMR methods. Physicochemical properties of products were also investigated. DW-116 is decomposed at 306.9$^{\circ}C$ and the decomposition starts at around 285$^{\circ}C$. The free base form is melt at 280.7$^{\circ}C$ and started to be decomposed immediately. DW-116 has two kinds of polymorphism which is important in drug action but these two plate and rod types have the same solubility in water. However the solubility is quite different in less or polar solvent. The plate type is more soluble in less polar solvent except in dichloromethane.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.3
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• pp.373-381
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• 2012

Antibiotics have been issued recently in water environments because of potential impacts on ecosystem and public health. This study was aimed to investigating the degradation of antibiotics such as tetracycline, lincomycin, sulfamethazine and cephradine using gamma ray irradiation. And the toxicity before and after irradiation on antibiotics was tested in order to examine the aquatic eco-risk assessment by aquatic organisms. In addition, comparing tests on toxicity for gamma ray and UV irradiated antibiotics was conducted. Four different antibiotics were prepared by concentration of 30 mg/L with demi-water respectively. The absorption dose of gamma ray was ranged from 0.2 to 2 kGy. The concentration of four antibiotics was gradually decreased corresponding to the increase of the absorption dose. A method for toxicity assessment using Pseudokirchneriella subcapitata was evaluated to the most acceptable compared with methods by Daphnia magna and Microtox$^{(R)}$ in terms of sensibility. It showed that the reduction of toxicity on antibiotics treated by gamma ray was superior comparing to the test results obtained from UV treatment. By-products from antibiotics treated by gamma ray were easily decomposed by microorganism and their toxicity was also evaluated to low.

• Journal of the Korean Wood Science and Technology
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• v.35 no.5
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• pp.46-57
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• 2007

The leachability of boron in zinc borate (ZB)-modified oriented strandboard (OSB) from southern wood species was investigated in this study. The leaching experiments were conducted by exposing edge-sealed OSB samples under running water at $31^{\circ}C$ for 8, 24, 72, and 216 h. The results from leached samples were compared with those from the unleached controls. Boron leaching of the modified OSB occurred upon the initial water exposure, and the leaching rate decreased as the leaching time increased. Initial boric acid equivalent (BAE) level, wood species, and sample thickness swelling significantly influenced the leachability. There was no consistent effect of polyethylene glycol (PEG) on zinc borate leaching. The glue-line washing within OSB due to thickness swelling of the test samples under water and decomposition of the borate to form water-soluble boric acid were thought to be two possible causes for the observed leaching. The relationship between assayed BAE and leaching time followed a decaying exponential function for zinc borate treated OSB. From the boron/zinc ratio after each leaching period, boron element in ZB was more or less leachable. The material constant of the regression models allowed comparing the leachability of the modified OSB for various wood species. An unified leaching method for treated wood composite materials is needed.

• Korean Journal of Agricultural Science
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• v.33 no.2
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• pp.129-140
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• 2006

There are need to develop of merchandise of value added fresh ginseng because of high consciousness level of consumer and enlarge of markets for high quality products. The fresh ginseng after harvest was distributed to farmer partually but in general, it was to market by consigner or wholsaler directly after harvest. There were a high difference on storage period of fresh ginseng in different harvesting seasons. The reduction of value of commodities of fresh ginseng for storage period was caused by decomposition and tender of tissue. The storage temperature was under the freezing point and the packing method was sealing tightly by plastic film. As the quality of fresh ginseng was defined by naked eye, it was difficult to sort the quality of ginseng directly harvest.

• Journal of Korean Society on Water Environment
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• v.18 no.4
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• pp.411-419
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• 2002

In this study, the series of ultrasonic irradiation for removal of refractory aromatic compounds has been selected as a model reaction in the batch reactor system in order to obtain the reaction kinetics. The products obtained from the ultrasonic irradiation were analysed by GC and GC/MSD. The decomposition of benzene produced toluene, phenol, and C1-C4 compounds, while the intermediates during the ultrasonic irradiation of 2,4-Dichlorophenol(DCP) were phenol, HCl, catechol, hydroquinone, and benzoquinone. It was found that more than 80% of benzene, and 2,4-DCP solutions were removed within 2 hours in all reaction conditions. The reaction order in the degradation of these three compounds was verified as pseudo-zero or first order. From the fore-mentioned results, it can be concluded that the refractory organic compounds could be removed by the ultrasonic irradiation with radicals, such as $H{\cdot}$ and $OH{\cdot}$ radical causing the high increase of pressure and temperature. Finally, it appeared that the technology using ultrasonic irradiation can be applied to the treatment of refractory compounds which are difficult to be decomposed by the conventional methods.