• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.933-937
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• 2012

In the present study, we evaluate the sensitivity and optimal stripping voltammetry (SV) conditions of copper (Cu), which is one of the main trace heavy metals inducing the environmental contamination, using carbon nanotube (CNT) electrode. In addition, the reaction mechanism of stripping reaction of Cu is investigated. The electrochemical analyses such as squarewave stripping voltammetry (SWSV) and linear scan voltammetry (LSV) are used for the evaluations. As a result of that, the best SWSV conditions like squarewave amplitude of 15 mV, frequency of 60 Hz, deposition potential of -1.0V vs. Ag/AgCl and deposition time of 200s are determined with the measured Cu sensitivity of $1.824{\mu}A/{\mu}M$. As a driving force affecting the stripping reaction of Cu, surface reaction is more dominant one than diffusion. These results are compared with other reference results and it is confirmed that our suggested CNT electrode gives rise to better Cu sensitivity result than other references.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.187-187
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• 1996

세포질에 존재하는 100 kDa Phospholipase $A_2$(cPLA$_2$)는 인지질의 sn-2 위치의 에스테르결합을 가수분해함으로서 Prostaglandin과 Leukotriene등 Eicosanoids 생합성의 전구체인 아라키돈산과 Platelet activating factor(PAF)를 생합성하는 전구체를 동시에 생성시키는 효소로 염증과 세포손상등에 중요한 역할이 기대된다. 본 효소의 활성화 기전을 규명하고자 하는 최근의 활발한 연구에도 불구하고 불명확한 점이 많은 것이 현실이다. 특히 세포를 자극하였을 때 유리되는 아라키돈산의 증가율과 세포를 파괴한 후 조제한 가용성분획에서 측정한 활성의 증가율과는 많은 차이를 나타냈다. 이러한 결과부터 cPLA$_2$ 효소 자체를 활성화시키는 어떤 인자를 가정하였다. 최근, PLA$_2$의 또다른 형태인 14 kDa의 분비성 PLA$_2$의 in vitro 활성을 증가시키는 인자가 동정되어 그 생화학적 특성이 규명되고 있으나 이 인자는 cPLA$_2$의 활성에는 아무런 증가효과를 나타내지 않았다. 본 연구자들은 소의 뇌조직에서 cPLA$_2$의 활성을 증가시키는 인자를 발견하고 그의 생화학적인 특성을 규명하였다. 돼지 비장에서 정제한 cPLA$_2$를 사용하였으며 소의 뇌 조직의 가용성 분획으로부터 본 활성화 인자를 동정하였으며 그 활성분획을 양이온 크로마토그라피로서 Mono S EPLC와 Superose 12 Sepharose gel filtration 크로마토그라피를 이용하여 더욱 분리한 결과 약 70 kDa과 25 kDa에서 각각 용출되었다. 이렇게 부분정제한 활성은 췌장에서 분리한 group I과 흰주의 group I과 흰주의 혈소판에서 분리한 group II PLA$_2$에 대해서는 아무런 증가효과를 나타내지 않는 반면, cPLA$_2$의 활성만을 약 5배 증가시켰다. 본 활성은 cPLA$_2$ 효소량의 증가에 따라 활성의 증가효과가 정차 감소하므로 화학량적인 반응(Stoichiometric reaction)일 것으로 예상되었다.

• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.174-177
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• 2010

In this study, non-catalytic transesterification from rapeseed oil using supercritical methanol was carried out by varying the operation parameters such as temperature ($320{\sim}365{^{\circ}C}$), time (0~20 min), pressure (10~35 MPa), molar ratio of oil to methanol (1 : 15~60) and agitation speed (0~500 rpm). In order to evaluate the effects of reaction parameters on the content of fatty acid methyl esters (FAMEs), we carried out the study using a batch reactor. The content of FAMEs increased when the temperature increased. However, the content of FAMEs decreased with temperature above $335^{\circ}C$ and time above 5 min. The content of FAMEs increased with increasing the molar ratio of methanol to oil but the content of FAMEs was slightly affected by molar ratio of oil to methanol above 1 : 45 and pressure above 20 MPa. It was found that the agitation speed above 100 rpm slightly affected the content of FAMEs. The highest content of FAMEs in biodiesel (95%) was obtained under the reaction conditions: temperature of 335 ${^{\circ}C}$, time of 10 min, pressure of 20 MPa, molar ratio of 1 : 45 (oil to methanol) and agitation speed of 250 rpm.

• Applied Chemistry for Engineering
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• v.24 no.2
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• pp.161-164
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• 2013

In this study, the application of recovered metals from spent batteries by extraction was investigated for ozone decomposition as a catalyst. Among the recovered metals, Mn contents was the most important factor for ozone decomposition. It was also found that the deactivation rate of the catalyst was dependent on the Zn contents, while K contents and activities were not perfectly correlated for ozone decomposition. In addition, the catalytic activity the $TiO_2$ added catalyst was decreased, due to the reduction of Mn contents. The structural characteristics of maganase oxide was not associated with the catalytic activity for ozone decomposition.

• Tuberculosis and Respiratory Diseases
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• v.60 no.3
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• pp.314-320
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• 2006

Background : The overall response (20-30%) to chemotherapy in non-small cell lung cancer (NSCLC) is quite poor. Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme degradation. There is increasing evidence suggesting that the induction of HO-1 might have an important protective effect against oxidative stress including cisplatin containing chemotherapy. This study retrospectively investigated the relationship between HO-1 expression and the response to chemotherapy containing cisplatinin advanced NSCLC patients. Material and Methods : The medical records including the responses to chemotherapy of fifty nine cases were evaluated retrospectively, and the tissue samples of these patients were immunohistochemically stained for HO-1. Results : Forty three of the fifty nine patients(72.8%) showed positive staining for HO-1 in their cancer tissues. There was no significant difference according to the cell type, stage and tumor size. In addition, there was no correlation between HO-1 expression and the responses to chemotherapy. Conclusion : HO-1 expression in tumor tissue dose not predict the response to cisplatin containing chemotherapy in advanced NSCLC. Further prospective studies with a larger number of patients will be needed to confirm these results.

• Journal of the Korean Electrochemical Society
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• v.4 no.4
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• pp.176-181
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• 2001

This article covers the fundamentals of underpotential deposition (UPD), focussing on the importance of UPD in interfacial electrochemistry. Firstly, this article described the basic concepts of UPD, including underpotential shift and electrosorption valency. Secondly, the present article explained UPD of hydrogen, followed by hydrogen evolution or hydrogen absorption, giving special attention to the adsorption sites of hydrogen on metal surface and the absorption mechanism into Pd. Finally, this article briefly presented the important factors associated with UPD in various fields of interfacial electrochemistry from practical viewpoints.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.49-57
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• 2002

During the electrokinetic remediation, direct current applied to a soil-water-electrolyte system derives the variations of fluid transport phenomena in soil-water system and soil-water interface characteristics. Therefore, these variations affect the electrokinetic reaction. In this study, lab-scale electrokinetic remediation tests were performed to characterize the electrical and chemical parameters variation in soil. During the test, voltage gradient, electrical current, zeta potential and pH variations were measured. On the basis of experimental results, computer modeling techniques predicting the variations of these parameters are suggested.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.533-540
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• 2010

An activated carbon was tested for its ability to remove transition metal ions from aqueous solutions. Physical, chemical and liquid-phase adsorption characterizations of the carbon were done following standard procedures. Studies on the removal of Ni(II), Cu(II) and Fe(III) ions were attempted by varying adsorbate dose, pH of the metal ion solution and time in batch mode. The equilibrium adsorption data were fitted with Freundlich and Langmuir and the isotherm constants were evaluated, equilibrium time of the different three metal ions were determined. pH was found to have a significant role to play in the adsorption. The processes were endothermic and the thermodynamic parameters were evaluated. Desorption studies indicate that ion-exchange mechanism is operating.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.142-146
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• 2008

Titanium silicalite-1 catalyst was prepared using a $SiO_2-TiO_2$ xerogel and applied to allylchloride (ALC) epoxidation by $H_2O_2$ as oxidant in a batch reactor. The reaction temperature was varied from 25 to $55^{\circ}C$, and the concentrations of ALC and $H_2O_2$ were changed from 0.2 to 3 M and from 0.2 to 1.5 M, respectively. The kinetic data obtained were applied to the power rate law, Eley-Rideal, and a Langmuir-Hinshelwood model, and power rate law fits the experimental data best. Activation energy was 27.9 kJ/mol, and the reaction orders with respect to $H_2O_2$ and ALC were determined to be 0.41 and 0.52, respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.6
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• pp.183-194
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• 2013

Liquid urea based SCR has been used in the market to reduce NOx in the exhaust emission of the diesel engine vehicle. This system has several problems at low temperature, which are freezing below $-12^{\circ}C$, solid deposit formation in the exhaust, and difficulties in dosing system at exhaust temperature below $200^{\circ}C$. Also, it is required complicated exhaust packaging equipment and mixer due to supply uniform ammonia concentration. In order to solve these issues, solid urea, ammonium carbonate, and ammonium carbamate are selected as ammonia sources for the application of solid SCR. In this paper, basic research on reaction rate of three ammonia-transporting materials was performed. TGA (Thermogravimetric Analysis) and DTA (Differential Thermal Analysis) tests for these materials are carried out for various heating conditions. From the results, chemical kinetic parameters such as activation energy and frequency factor are obtained from the Arrhenius plot. Additionally, from test results of DSC (Differential Scanning Calorimeter) for these materials, chemical kinetic parameters using the Kissinger method are calculated. Activation energies of solid SCR from this experiment are compared with proper data of literature study, then obtained data of this experiment are used for the design of reactor and dosing system for candidate vehicle.