• 분석과학
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• 제18권1호
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• pp.89-95
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• 2005

Studies on the electrochemical reduction of 7-acetoxy-4-bromomethyl-coumarin (ABMC), 7-acetoxymethyl coumarin (AMC), and coumarin in 0.1 M tetraethyl ammonium perchlorate acetonitrile solution were carried out with direct current, differential pulse polarography, cyclic voltammetry, and controlled potential coulometry. The electrochemical reduction of ABMC was proceeded through three irreversible steps coupled with the chemical reactions. The solution color was changed to yellow when the carbonyl group was reduced during second step and the color change was independent with bromo group of ABMC. Fluorescent intensity was highest when the electrochemical reduction was controlled at near the overpotential of supporting electrolyte (-2.3 volts).

• 분석과학
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• 제11권5호
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• pp.400-403
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• 1998

The germanium content of the cultivated Korean medicinal herbs in several growing district was determined by adsorption stripping voltammetry. The optimum conditions in germanium determination were as following: deposition time; 120 sec, deposition potential; -0.9 volts vs. Ag/AgCl, and frequency; 100 Hz in $5.0{\times}10^{-2}M$ perchloric acid supporting electrolyte solution containing $8.0{\times}10^{-2}M$ catechol. Calibration curve was shown a good lineality in the range of 0.4 ppb to 2.0 ppm and the detection limit was 0.08 ppb. There was a large difference in content of the cultivated hermit leaf according to growing district such as 29.7~385.7 ppm and the content of nontreated hermit leaf was higher than the processed health foodstuffs. The content of the Korean ginseng (5 years) was 83 ppm while the Korean herb of life was 214 ppm.

• 대한화학회지
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• 제32권1호
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• pp.30-36
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• 1988

에틸렌디아민, 프로필렌디아민 및 디에틸렌트리아민의 구리(II), 카드뮴(II) 및 아연(II) 착이온의 安定度에 미치는 壓力의 影響을 폴라로그래피로 조사하였다. 支持電解質로서는 0.10M의 KN$O_3$ 용액을 쓰고, 킬레이트제의 농도는 0.01M에서 0.1M까지 변화시켰다. 압력이 1기압에서 1,500기압으로 증가함에 따라 금속착이온의 解離常數는 증가하였으며, 단위압력당 증가율은 $Cu(dien)_2^{2+}$의 1.1 ${\times} 10^{-3}$ %에서 Zn(en)$_2^{2+}$의 5.0${\times} 10^{-3}$ % 까지의 값으로 나타났다.

• 전기화학회지
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• 제10권3호
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• pp.159-168
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• 2007

An electrochemical study related to the redox characteristics of Ethyl-3-acetyl-6-methyl-1, 4-diphenyl-4, 3a-dihydro-1, 3, 4-triazolino[3, 4-a] pyrimidine-5-carboxylate ester and its derivatives (1a-f) and (2a-e) in nonaqueous solvents such as 1, 2-dichloroethane (DCE), dichloromethane (DCM), acetonitrile (AN), dimethylsulphoxide (DMSO) and tetrahydrofurane (THF) using $0.1\;mol\;dm^{-3}$ tetrabutylammonium perchlorate (TBAP) as a supporting electrolyte at platinum, glassy carbon and gold electrodes, has been performed using cyclic voltammetry (CV). Controlled potential electrolysis (CPE) is also carried out to elucidate the course of different electrochemical reactions through the separation and identification of the intermediates and final electrolysis products. The redox mechanism is suggested and proved. It was found that all the investigated compounds in all solvents are oxidized in a single irreversible one electron donating process following the well known pattern of the EC-mechanism to give a dimer. On the other hand, these compounds are reduced in a single irreversible one electron step to form the anion radical, which is basic enough to proton from the media forming the radical which undergoes tautomerization and then dimerization processes to give also another bis-compound through N-N linkage formation.

• 분석과학
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• 제8권2호
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• pp.171-179
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• 1995

흡착벗김전압전류법을 이용하여 게르마늄 분석을 하였으며, 리간드로는 Tannic acid를 사용하였다. 수집전위는 -0.2V, 수집시간은 60초, 평형시간은 20초, 주파수는 10Hz였다. 작업전극으로는 매달린 수은전극을 이용하였고 지지전해질로는 pH=4.5인 아세트산 완충용액을 사용하였다. 게르마늄의 분석을 위한 리간드의 알맞은 조건을 알아내었고 게르마늄 봉우리 전류에 대한 금속이온(납, 구리, 규소, 주석, 갈륨)의 영향에 대하여 조사하였다.

• 신재생에너지
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• 제2권4호
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• pp.64-69
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• 2006

There is a worldwide interest in the development and commercialization of polymer electrolyte membrane fuel cells [PEMFCs] for vehicular and stationary applications. One of the major objectives is the reduction of loaded electrode materials, which is comprise of the Pt-based noble metals. In this paper, a novel chemical strategy is described for the preparation and characterization of carbon-supported and surface-alloys, which were prepared by using a successive reduction process. After preparing Au colloid nanoparticles, the supporting of Au colloid nanoparticles occurred spontaneously in the carbon black-dispersed aqueous solution. Then nano-scaled active materials were formed on the surface of carbon-supported Au nanoparticles. The structural and electrochemical analyses indicate that the active materials were deposited on the surface of Au nanoparticles selectively and that an alloying process occurred during the successive reducing process. The carbon-supported & surface-alloys showed the higher electrocatalytic activity than those of the particle-alloys and commercial one [Johnson-Matthey] for the reaction of methanol and formic acid oxidation. The increased electrocatalytic activity might be attributed to the effective surface structure of surface-alloys, which have a high utilization of active materials for the surface reaction of electrode.

• 전기화학회지
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• 제17권3호
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• pp.201-208
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• 2014

본 연구에서는 산화그래핀과 카본블랙의 혼합담체를 이용하여 내구성이 향상된 백금촉매를 폴리올법으로 제조하였다. 삼전극 순환전압전류법을 이용한 전기화학성능 측정결과 적절한 비율로 조절된 혼합담지체에 백금을 담지시켰을 경우 초기 성능 감소없이 장기내구성이 향상되는 것으로 나타났다. 또한 회전원판전극을 이용하여 산소환원반응을 수행한 결과 혼합담체에 담지된 백금촉매가 카본블랙 단일담체에 담지된 백금촉매보다 우수한 고유활성값을 나타내었다.

• 대한화학회지
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• 제32권2호
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• pp.130-134
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• 1988

수은방울전극에서 바로 시안이온을 시차펄스음극벗김 전압전류 법으로 측정한 결과 검출한계를 낮출수가 있었다. 가장 알맞는 실험조건은 다음과 같다. : 0.1M KCl-0.01M 인산염 지지전해질, pH 7, 석출전위 0.00V, 그리고 석출시간 3분이었다. 이 조건에서 검출한계는 $3{\times}10^{-7}M$ (8ppb) $CN^-$이다.

• 대한화학회지
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• 제17권5호
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• pp.357-362
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• 1973

과염소산나트륨으로 이온강도를 0.1로 조절한 histidine용액 중에서 Pb(II), Cd(II) 및 Cu(II)의 polarography적 거동을 조사하였다. 그리고 Pb(II), Cd(II) 및 Cu(II)들의 각각의 histidine과 수산화이온과의 혼합착물의 생성정수를 Schaap의 방법에 의하여 구하였으며, 또한 이 계에서의 전극반응도 검토하였다.

• 대한화학회지
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• 제9권3호
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• pp.121-123
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• 1965

Ni(II)-Monoethanolamine(MEA)錯鹽의 水銀電極表面에 있어서의 還元反應의 反應機構를 폴라로그라프법을 써서 解明하였다. 이 錯鹽의 電極環元의 可逆程度를 直流 및 交流 폴라로그람으로 檢討하였더니 pH가 9.0보다 낮은 範圍에서는 錯鹽의 反應電流로 推測되는 非可逆性波를 나타니고 pH $9.5{\sim}11.0$ 사이에서는 Cd(II)波에 相當하는 比較的 可逆的인 well defined wave를 얻었다. MEA의 濃度와 pH를 變함으로서 얻은 波를 檢討한 結果 還元波는 이를 ligands와 빠른 平衡에 있는 Ni錯鹽에 基因하고 이 錯鹽의 化學式은 $Ni(MEA)_3OH$이고 總安定度常數는 約 $10^{20}$임을 밝혀내었다.