• Analytical Science and Technology
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• v.23 no.1
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• pp.24-35
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• 2010

To learn more about the calibration properties of reduced sulfur compounds (RSCs) by the combination of gas chromatography(GC)-pulsed flame photometric detector (PFPD) and thermal desorption method, a series of calibration experiments were conducted on the basis of both internal and external calibration approaches. For these experiments, gaseous standards of 4 RSCs ($H_2S$, $CH_3SH$, DMS, and DMDS) were prepared at two different concentration levels of both low (10, 20, 50,and 100 ppb) and high ranges (100, 200, 500, and 1000 ppb) along with $CS_2$ as an internal standard. First, the external calibration results were compared between fixed standard volume (FSV) and fixed standard concentration (FSC) method. Secondly, FSV-based calibration results were compared between external and internal calibration results. As FSV method suffers from sensitivity variations less significantly than FSC, the former is recommended to maintain the consistency in GC-TD sensitivity for RSC analysis. In addition, when the calibration data were examined in terms of RSE between external and internal calibration data, the results were not consistent enough to show improvements in internal method. Hence, diverse efforts are desirable to optimize the reproducibility in terms of GC-TD sensitivity for RSC analysis.

• Journal of the Korean Chemical Society
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• v.59 no.1
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• pp.36-44
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• 2015

This article describes synthesis and electrochemical properties of layer-by-layer self-assembled multilayer film composed of polyaniline (PANi), graphene oxide (GO) and phytic acid (PA), whereby the GO was electrochemically reduced to ERGO, resulting in $(PANi/ERGO/PANi/PA)_{10}$ film electrode. Especially, we examined the possibility to improve the volumetric capacitive property of $(PANi/ERGO)_{20}$ film electrode via combining a spherical hexakisphosphate PA nanoparticle into the multilayer film that would dope PANi properly and also increase the porosity and surface area of the electrode. The electrochemical performances of the multilayer film electrodes were investigated using a three-electrode configuration in 1 M $H_2SO_4$ electrolyte. As a result, the $(PANi/ERGO)_{20}$ electrode showed the volumetric capacitance of $666F/cm^3$ at a current density of $1A/cm^3$, which was improved to the volumetric capacitance of $769F/cm^3$ for the $(PANi/ERGO/PANi/PA)_{10}$ electrode, in addition to the cycling stability maintained to 79.3% of initial capacitance after 1000 cycles. Thus, the electrochemical characteristics of the $(PANi/ERGO)_{20}$ electrode, which was densely packed by ${\pi}-{\pi}$ stacking between the electron-rich conjugate components, could have been improved through structural modification of the multilayer film via combining a spherical hexakisphosphate PA nanoparticle into the multilayer film.

• Journal of Soil and Groundwater Environment
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• v.12 no.5
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• pp.115-123
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• 2007

Immobilization of contaminants in subsurface environment is one of the major processes that determine their fate. Especially, immobilization by oxidative-coupling reactions, which is irreversible in the bio-chemical reactions and results in a significant reduction of toxicity, can be successfully applied for the remediation of contaminated soil and groundwater more effectively than conventional degradation. As a catalyst of this oxidative-coupling reaction, manganese oxide has many advantages in practical aspects as compared to microorganisms or oxidoreductive enzymes extracted from microorganisms, fungi, or plants. This paper is to present recent research achievements on the treatment mechanisms of various organic contaminants by manganese oxide. Especially, treatment methods of non-reactive organic compounds to Mn oxide are the main focus; i.e., application of reaction mediator, PAHs treatment method, combination with an appropriate pretreatment such as reduction using $Fe^0$, which suggests the potential of a wide range of engineering application. Concerning the natural carbon cycle processes, immobilization and stabilization by oxidative coupling reaction can be effectively applied as a environmentally-friend remediation method especially for aromatic contaminants which possess a high resistance to degradation.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.4
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• pp.111-120
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• 2014

The aim of this study is to develop an integrated urea-SCR catalytic filter system for reducing soot and $NO_X$ emissions simultaneously in diesel engines. In this study, the characteristics of exhaust emissions relative to reactive activation temperature under four kinds of engine loads are experimentally investigated by using a four-cycle, four-cylinder, direct injection type, water-cooled turbo intercooler ECU common-rail diesel engine with the integrated urea-SCR $MnO_2-V_2O_5-WO_3/TiO_2/SiC$ catalytic filter system operating at three kinds of engine speeds. The urea-SCR reactor is used to reduce $NO_X$ emissions, and the catalytic filter system is used to reduce soot emissions. The reactive activation temperature is very important for reacting a reducing agent with exhaust emissions. The reactive activation temperatures in this experiment is applied to 523, 573 and 623 K. The fuel is sprayed by the pilot and main injections at the variable injection timing between BTDC $15^{\circ}$ and ATDC $1^{\circ}$ according to experimental conditions. It is found that the $NO_X$ conversion rate is the highest as 83.9% at the reactive activation temperature of 523 K in all experimental conditions of engine speed and load, and the soot emissions shown by the average reduction rate of approximately 93.3% are almost decreased below 0.6% in all experimental conditions regardless of reactive activation temperatures. Also, the THC and CO emissions by oxidation reaction of Mn, V and Ti are shown in the average reduction rates of 70.3% and 38% regardless of all experimental conditions.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.132-132
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• 1993

정상세포의 암세포로의 전환에 수반하는 세포표면상에 당구조 변화가 주목을 받고 있으며 이에 탄수화물이 세포간의 상호작용, 성장 등에 중요한 역할을 하리라고 생각된다. 따라서, 당구조 변화를 야기 시키는 당분해소효소나 전이활성 효소의 활성이 주요한 임상적 지표가 될 수 있다. 또한 천연물에서 유래된 다당류 등이 면역증강 효과를 나타내면서 항종양 효과를 보여준다. 이와같은 일을 원활히 수행하기 위해서는 당을 분석하는 기술이 필요하다. 당을 분석하는 방법으로 많이 이용된 것 중의 하나가 유도체를 만들어 GC에 의해서 확인하는 것이고 또한 당은 chromophore가 없기 때문에 굴절율의 검출기를 이용한 HPLC에 의해서도 분석이 가능하다. HPLC에 의한 또 다른 방법으로 당의 환원당 말단에 형광기를 결합시켜 감도를 매우 높게하여 역상 칼람을 이용해 당을 분리할 수 있다. 환원당에 결합시킬 수 있는 물질로는 대부분 amine기를 띄고 있고 결합하여 형광을 나타내는 특징을 지니고 있다. 본 연구는 형광기를 결합시켜 전기영동과 HPLC에 의해 동시에 추적이 가능한 물질을 결합시켜서 분석을 용이하게 한 방법을 이용하여 단당류를 $C_{18}$ column에 의해서 분리하였고 또한 모델로서 면역증강제로 사용되는 운지버섯 및 영지버섯 다당류와 생약에서 분리한 지유의 당을 분석하였다. 현재까지의 결과로 가장 좋은 방법은 $C_{18}$-->phenyl column을 연결하여 isocratic 방법으로 분리하였을 때이었다. 버섯의 당은 대부분이 glucose로 이루어졌고 지유는 arabinose가 주 구성성분이었다. 위의 분석 기술을 이용하면 피코몰 범위내에서 정확한 구조를 가진 항암효과의 올리고당 및 암세포의 발현에 따른 당단백질의 당의 구조를 규명하는데 도움을 줄 수 있다.aeonol이 aspirin과 같거나 강한 사망 억제 효과가 있었다.cyclopropyl-7-(2-furanyl) -6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid (compound 4), 1-cyclopropyl-7-(2-thiophenyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid (compound 6) ,1-cyclopropyl-7-(3-pyridinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid (compound 8), 1-cyclopropyl-7-(2-fluoro-3-pyridinyl)-6-fluoro-1,4-dihydro-4-oxo-3-quinoline carboxylic acid (compound 10)를 합성하였다.10^{－7}$ M)에 의한 단백인산화에 대하여는 더 미약한 억제-효과를 나타내었다. 이상의 결과는 PDE-1과 항우울약들의 항혈소판작용은 PKC-기질인 41-43 kD와 20 kD의 인산화를 억제함에 기인되는 것으로 사료된다.다. 것으로 사료된다.다.바와 같이 MCl에서 작은 Dv 값을 갖는데, 이것은 CdCl$_{4}$$^{2-}$ 착이온을 형성하거나 ZnCl$_{4}$$^{2-}$ , ZnCl$_{3}$$^{-}$같은 이온과 MgCl$^{+}$, MgCl$_{2}$같은 이온종을 형성하기 때문인것 같다. 한편 어떠한 용리액에서던지 NH$_{4}$$^{+}$의 경우 Dv값이 제일 작았다. 바. 본 연구의 목적중의 하나인

• Economic and Environmental Geology
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• v.40 no.5
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• pp.575-585
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• 2007

Microbial control of the geochemical behavior of heavy metals (Cd, Cu, Pb, and Zn) and As in contaminated subsurface soil and sediment was investigated through activation of indigenous bacteria with lactate under anaerobic condition for 25 days. The results indicated that dissolved Cd, Pb and Zn were microbially removed from solutions, which was likely due to the formation of metal sulfides after reduction of sulfate by indigenous sulfate-reducing bacteria. Soils from the Dukeum mine containing a large amount of sulfate resulted in complete removal of dissolved As after 25 days by microbial activities, while there were gradual increases in dissolved As concentration in soils from the Hwabuk mine and sediments from the Dongducheon industrial area which showed low $SO_4{^2-}$ concentrations. Addition of appropriate carbon sources and sulfate to contaminated geological media may lead to activation of indigenous bacteria and thus in situ stabilization of the heavy metals; however, potential of As release into solution after the amendment should be preferentially investigated.

• Economic and Environmental Geology
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• v.40 no.5
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• pp.551-561
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• 2007

This case study is about the sampling and interpretation of soil pore water in order to understand and to predict the diffusion and behavior of soil pollution. For the measurement of polycyclic aromatic hydrocarbons(PAHs) in two representative hydrocarbon-contaminated sites, the extraction system of the soil pore water was set up with respect to soil depths and the behavior of contaminants was interpreted. The soil solution extraction system consisted of peristaltic pump, and extraction and sampling compartment, and can measure simultaneously the soil water pressure. The concentration of PAHs with respect to extraction pressure and time decreased due to dilution through soil pore water. Particularly, the concentration of PAHs was more reduced under the unsaturated oxic condition than saturated anoxic condition. Therefore, the soil solution extraction with respect to soil water pressure can interpret the extent of equilibrium between porewater and soil surface.

• Economic and Environmental Geology
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• v.53 no.3
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• pp.235-244
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• 2020

Copper (Cu), one of the main contaminants in the mine drainage from the closed mine area, needs to be removed before exposed to environment because of its toxicity even in the low concentration. In this study, passive treatment based field pilot experiments using limestone and compost media were conducted during 9 months for enhancing Cu removal efficiency of the mine water treatment facility of S mine located in Goseong, Gyeongsangnam-do in South Korea. The pH increase and Cu removal efficiency showed high value at Successive Alkalinity Producing System ( SAPS) > Reducing and Alkalinity Producing System (RAPS) > limestone reactor in a sequence. The compost media using in SAPS and RAPS contributed to raise pH by organic material decomposition with generating alkalinity, thus, Cu removal efficiency increased. Also, experimental results showed that Cu removal efficiency was proportional to pH increase, meaning that pH increase is the main mechanism for Cu removal. Moreover, Sulfate Reduction Bacteria (SRB) was identified to be most activated in SAPS. It is inferred that the sulfate reduction reaction also contributed to Cu removal. This study has the site significance in that the experiments were conducted at the place where the mine water generates. In the future, the results will be useful to select the more effective reactive media used in the treatment facility, which is most appropriate to remediate mine water from the S mine.

• Applied Chemistry for Engineering
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• v.16 no.4
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• pp.527-532
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• 2005

Ionic polymer metal composites (IPMC) are soft polymeric smart materials having large displacement at low voltage in air and water. The polymeric electrolyte actuator consists of a thin and porous membrane and metal electrodes plated on both faces, in impregnation electro-plating method. The response and actuation of actuator are governed. Among many factors governing the activation and response of IPMC actuator, the surface electrode plays an important role. In this study, the well-designed modification of electrode surface was carried out in order to improve the chemical stability well as electromechanical characteristics of the IPMC actuator. We employed Ion Beam Assisted Deposition (IBAD) method to prepare the topologically homogeneous thin surface electrode. After roughing the surface of Nafion membrane in order to get a larger surface area, the IPMC was prepared by impregnation for electro-plating and re- coating on the surface through traditional chemical deposition, followed by an additional surface treatment with high conductive metals with IBAD. It was observed that our IPMC specimen shows the enhanced surface electrical properties as well as the improved actuation and response characteristics under applied electric field.

• Korean Journal of Clinical Laboratory Science
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• v.50 no.2
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• pp.205-210
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• 2018

Salvianolic acid B, which is a compound in the Salvia miltiorrhiza, has diverse biological activities, In particular, the antioxidative effects were reported to be involved in the protection of hepatocytes, neurons, and various cell types. On the other hand, some phenolic compounds, such as ferulic acid, which is regarded as an antioxidant, plays a pro-oxidative role in the specific transitional metal environment, which could explain the anticancer effect. This study examined the pro-oxidative effects of salvianolic acid B in the presence of $Cu^{2+}$. Treatment with both salvianolic acid B and $Cu^{2+}$ induced the transition of supercoiled DNA to the open circular or linear form but not in the sole salvianolic acid B or $Cu^{2+}$ treatments. Salvianolic acid B reduced the $Cu^{2+}$ to $Cu^+$ using neocuproine, a $Cu^+$ specific chelator. In addition, catalase, an enzyme that breaks down the $H_2O_2$ to water and molecular oxygen, inhibited the DNA breakage. $H_2O_2$, a reactive oxygen species, has detrimental effects on biological molecules, particularly DNA. Overall, the reduction of $Cu^{2+}$ by salvianolic acid B could lead to the production of $H_2O_2$ followed by DNA breakage. These results suggest that the pro-oxidative effects could be the one of the anti-cancer mechanisms of salvianolic acid B, which remains to be explained.