• Journal of Korean Society of Environmental Engineers
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• v.32 no.9
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• pp.894-899
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• 2010

We coordinated the experiments with ozone pretreatment and two-phase anaerobic digestion using solid-liquid separation to raise the efficiency of sludge volume reduction and obtained the following results. The pre-treatment with ozone reduced the solid concentration in the average of TSS $8.3{\pm}2.0%$ TSS and $9.2{\pm}}2.8%$ VSS. Of the organic material, TCOD decreased $5.1{\pm}2.4%$, but SCOD showed $72{\pm}6.5%$ increased, which was due to destruction of the cell wall and dissolution of icell media by the powerful oxidative stress of ozone. During the two-phase anaerobic digestion process, we achieved the reduction of $21.5{\pm}3.4%$ TSS, $20.2{\pm}8.4%$ VSS, $32.1{\pm}7.9%$ TCOD and $22.1{\pm}7.2%$ SCOD in average. The maximum methane gas production were 177.6 mL per g TSS, 210.8 mL per g VSS, 127.0 mL per g TCOD and 1452.0 mL per g SCOD, respectively. Solid material reduction through the two-phase anaerobic digestion and MLE (Modified Ludzack-Ettinger) processes were 93.8% of TSS and 92.0% of VSS. We concluded that suggested two-phase anaerobic digestion and MLE process could achieve the reasonable production of biogas and a maximum reduction of the sludge volume.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.213-217
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• 2001

In order to develop a new separation technology, supercritical fluid extraction process was used to produce high purity pigments and fatty acids from seaweed (Undaria pinnatifida). Supercritical carbon dioxide was used as a solvent and ethanol as an entrainer. The sample was treated by a frozen drier and experiments were conducted with a semi-batch flow system at various operating conditions (pressure range, $10.3\~17.2$ MPa; temperature range, $30\~45^{\circ}C$: particle size, $500\~1,000{\mu}m$ extraction time, 60 min). Characteristics of the recovered pigment (chlorophyll a) and fatty acids were determined by UV-spectrophotometry and gas chromatography, respectively. The highest extraction efficiency for fatty acids and pigments was achieved at 12.4 MPa, $35^{\circ}C$, $500{\mu}m$of seaweed size.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.355-361
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• 1991

The separative preconcentration of trace mercury[Hg(II)] in a water sample was studied by a coprecipitation flotation technique. The trace Hg(II) was precipitated together with Ce(OH)$_3$ by adding 3.0 ml of 0.1M Ce$^{3+}$ solution to 1,000 ml of water sample and adjusting pH to 11.0 with 1.0M NaOH solution. The hydrophobic precipitate[Ce(OH)$_3$-Hg(OH)$_2$], which was formed by adding 2.0 ml of 0.1${\%}$ ethanolic sodium oleate solution, were floated on the surface with an aid of tiny nitrogen gas bubbles. The floated materials were quatitatively collected in a suction flask and dissolved with 5.0 ml of 2.0M HNO$_3$. The solution was marked to 25.00 ml with a deionized water. The content of Hg(II) was determined by cold vapor atomic absorption spectrophotometry. Any interferences of concomitants such as Ag$^+$, Br$^-$, I$^- $, etc. were not observed on the whole procedure. The analytical result showed that Hg(II) found in the wastewater of Seochang Campus, Korea University was 1.98 ng/ml with the relative standard deviation of 3.6${\%}$. And recoveries of Hg(II) in the wastewater into which 1.0 ng/ml and 2.0 ng/ml were added were 95${\%}$ and 91${\%}$, respectively. From such results, this procedure could be concluded to be tolerably accurate and reproducible for the determination of trace mercury in a water sample.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1121-1126
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• 2009

This paper describes a pattern recognition method of Magnoliae flos based on a gas chromatographic/mass spectrometric (GC/MS) analysis of the essential oil components. The botanical drug is mainly comprised of the four magnolia species (M. denudata, M. biondii, M. kobus, and M. liliflora) in Korea, although some other species are also being dealt with the drug. The GC/MS separation of the volatile components, which was extracted by the simultaneous distillation and extraction (SDE), was performed on a carbowax column (supelcowax 10; 30 m{\time}0.25 mm{\time}0.25{\mu}m$) using temperature programming. Variance in the retention times for all peaks of interests was within RSD 2% for repeated analyses (n = 9). Of the 74 essential oil components identified from the magnolia species, approximately 10 major components, which is $\alpha$-pinene, $\beta$-pinene, sabinene, myrcene, d-limonene, eucarlyptol (1,8-cineol), $\gamma$-terpinene, p-cymene, linalool, $\alpha$-terpineol, were commonly present in the four species. For statistical analysis, the original dataset was reduced to the 13 variables by Fisher criterion and factor analysis (FA). The essential oil patterns were processed by means of the multivariate statistical analysis including hierarchical cluster analysis (HCA), principal component analysis (PCA) and discriminant analysis (DA). All samples were divided into four groups with three principal components by PCA and according to the plant origins by HCA. Thirty-three samples (23 training sets and 10 test samples to be assessed) were correctly classified into the four groups predicted by PCA. This method would provide a practical strategy for assessing the authenticity or quality of the well-known herbal drug, Magnoliae flos.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.395-401
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• 2016

Background: Liquid scintillation counters (LSCs) are commonly used as an analytical method for detecting $^{222}Rn$ in groundwater because they involve a simple sample pretreatment and allow high throughout with an autosampler. The Quantulus 1220 is the best-selling LSC in Korea, but its production was stopped. Recently, a new type of LSC, the 300SL, was introduced. In this study, the 300SL was compared with the Quantulus 1220 in order to evaluate the ability of each apparatus to detect $^{222}Rn$ in groundwater. Materials and Methods: The Quantulus 1220 and 300SL were used to detect the presence of $^{222}Rn$. Radon gas was extracted from a groundwater sample using a water-immiscible cocktail in a LSC vial. The optimal analytical conditions for each LSC were determined using a $^{222}Rn$ calibration source prepared with a $^{226}Ra$ source. Results and Discussion: The optimal pulse shape analysis level for alpha and beta separation was 80 for the Quantulus 1220, and the corresponding pulse length index was 12 in the 300SL. The counting efficiency of the Quantulus 1220 for alpha emissions was similar to that of the 300SL, but the background count rate of the Quantulus 1220 was 10 times lower than that of the 300SL. The minimum detectable activity of the Quantulus 1220 was $0.08Bq{\cdot}L^{-1}$, while that of the 300SL was $0.20Bq{\cdot}L^{-1}$. The analytical results regarding $^{222}Rn$ in groundwater were less than 10% different between these LSCs. Conclusion: The 300SL is an LSC that is comparable to the Quantulus 1220 for detecting $^{222}Rn$ in groundwater. Both LSCs can be applied to determine the levels of $^{222}Rn$ in groundwater under the management of the Ministry of Environment.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.810-815
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• 2011

Concentrated water discharged from seawater desalination process contains a high concentration of $Na^+$ ion. Electrolysis was applied to synthesize NaOH solution from the highly concentrated NaCl solution. The effect of various operating parameters of composited laboratory-scale chlor-alkali (CA) membrane cell was investigated. The operating parameters such as membrane types (CIMS and Nafion membranes), pretreatment of the membrane, flow rate (73 mL/min~200 mL/min), initial $Na^+$ ion concentration (1.5 M, 3M and 5 M) and current (1.5A and 2A) were evaluated. It was observed that synthesis efficiency of NaOH solution with CIMS membrane was higher than that with Nafion membrane, but the durability of CIMS membrane on $Cl_2$ gas was poor. The synthesis efficiency of NaOH solution increased with increasing initial $Na^+$ ion concentration and current, while the efficiency decreased with increasing flow rate using Nafion membrane.

• Membrane Journal
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• v.19 no.4
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• pp.261-267
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• 2009

Polyimide which is the glassy polymer has high chemical resistance, thermal stability and high mechanical property. In this study, the polyimide hollow fiber membranes were prepared by the dry-jet wet phase inversion in order to investigate the permeation porperties of the $H_2S$ and $CH_4$. The morphology of prepared hollow fiber membranes and their permeation behaviors of $H_2S$ and $CH_4$ before and after silicon coating were evaluated. The permeance of $H_2S$ and $H_2S/CH_4$ selectivity increased due to plasticization with increasing the feed pressure. The permeance of KSM03b and selectivity of KSM03d were highest among the three type membranes used this experiments. The permeance decreased but the $H_2S/CH_4$ selectivity increased with increasing the air gap. The permeance reduced after silicon coating. However, the selectivity increased and the selectivity of KSM03d was 275 at 7 atm.

• Membrane Journal
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• v.26 no.5
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• pp.381-390
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• 2016

In this study, the natural mordenite (MOR) zeolite seeds were used for the synthesis of high purity mordenite crystals. The effect of seed concentration and crystallization time on the phase purity and surface morphology of MOR crystals has also been reported. The diffraction, elemental and scanning analysis of MOR zeolite particles obtained from 100 g hydrothermal solution batch containing 3 g natural seed, hydrothermally treated at $140^{\circ}C$ for 72 h reveal the high phase-purity of as-synthesized sample having crystals of uniform size ($1-2{\mu}m$). Moreover, high seed concentration leads to the production of mesoporous MOR particles composed of needle shape primary nano crystallites. The gases adsorption performances of as-synthesized MOR particle were carried out at $25^{\circ}C$ and 0-1 bar. Surprisingly, MOR particles show good adsorption potential for $CO_2$ (97.19 mg/g) compared to other gases. Thus it confirms that high purity MOR particles can be synthesized without using any organic template which gives an advantage of separation performance at lower price.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.12-17
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• 2005

Despite a wide range of fatty acids in fish oil, its the usage are very limited owing to off-flavors and volatile compounds in the oil. A way to extract and remove volatile compounds was performed at a semi-flow extractor by using supercritical carbon dioxide $(SC-CO_2)$. Samples of the oil were treated at the conditions which ranged from $30\;to\;80^{\circ}C$ and from 80 to 200 bar with 10 mL/min flow rate of carbon dioxide. In the oil the volatile compounds were analyzed by gas chromatography. Before extraction with $SC-CO_2$ the oil sample was detected over 129 peaks but 99 compounds were identified. The results demonstrated that at $40^{\circ}C$ and 200 bar extraction condition the volatile compounds in the tuna fish oil were removed, except for 14 compounds identified after extraction and other $SC-CO_2$ extraction conditions reached to high reduction of the volatile compounds.

• Resources Recycling
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• v.25 no.6
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• pp.13-22
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• 2016

This study is aimed at compare and evaluate the environmental impact of End-of-Life Vehicle(ELV) on the eco-friendly technology dismantling and recycling system, using Life Cycle Assessment (LCA) method. In this study, it was analyzed for the environmental impacts of raw materials, disassemble process, recycle parts separation and waste treatment into the process of ELV treatment by greenhouse gas and resource consumption, etc. Through this study, the indoor rail type dismantling technology were recycling rate applied on the alternate system was increased by approximately 8%. As a result, it was 3 to 88% by improving the environmental impact category. In addition, the added benefit of approximately 8 - 62% in pre-market occurred through the recycling rate, improve parts reuse rate of ELV. Through the results of this study, legal compliance, improved reuse and recycling ratio, used parts market reach, enable exports has identified the need for the effort that the dissemination and diffusion of eco-friendly technology.