• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.23-27
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• 2003

Molecular self-assembled of surfactant viologen are of recent interest because they can from functional electrodes as well as micellar assemblies, which can be profitably utilized for display devices, photoelectrochemical studies and electrocatalysis as electron acceptor or electron mediator. Fromherz et al studied the self-assembly of thiol and disulfide derivatives of viologens bearing long n-alkyl chains on Au electrode surface. The electrochemical behavior of self-assembled viologen monolayer has been investigated with QCM, which has been known as nano-gram order mass detector. The self-assembly process of viologen was monitored using resonant frequency$({\Delta}F)$ and resonant resistance(R). The redox process of viologen was observed with resonant frequency $({\Delta}F)$.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1520-1522
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• 2003

Molecular self-assembled of surfactant viologen are of recent interest because they can from functional electrodes as well as micellar assemblies, which can be Profitably utilized for display devices, photoelectrochemical studies and electrocatalysis as electron acceptor or electron mediator. Fromherz et al studied the self-assembly of thiol and disulfide derivatives of viologens bearing long n-alkyl chains on Au electrode surface. The electrochemical behavior of self-assembled viologen monolayer has been investigated with QCM, which has been known as nano-gram order mass detector. The self-assembly process of viologen was monitored using resonant frequency (${\Delta}$F) and resonant resistance (R). The redox process of viologen was observed with resonant frequency (${\Delta}$F).

• YAKHAK HOEJI
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• v.36 no.3
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• pp.285-290
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• 1992

After rats were exposed to 5,000 ppm carbon monoxide for 30 minutes, the amounts of catecholamine neurotransmitters in stratum were measured using high performance liquid chromatograph equipped with electrochemical detector. The concentration of dopamine in stratum was significantly decreased after carbon monoxide intoxification, but those of dihydroxyphenylacetic acid, norepinephrine, and epinephrine was not changed. However the pretreatments of Ginseng total saponin and panaxatriol saponin increased the concentrations of dopamine and its acidic metabolites (DOPAC and HVA). Ginseng total saponin also increased the concentrations of norepinephrine and epinephrine. Similar results were obtained from aged rats.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2404-2406
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• 2005

본 연구에서는 전기촉매제를 사용하여 증가된 감도를 가지는 검출 시스템을 제작하였다. 전극과 검출물질 사이의 산화환원반응을 촉진시키기 위한 물질로 Prussian blue (PB)를 indium tin oxide (ITO) 전극에 전착하였다. 본 실험에서는 분석물질의 이동 및 분리를 위하여 모세관 전기영동방법을 사용하였으며 측정방법은 전류량법을 사용하였다. 전착된 PB 박막의 특성은 원자 현미경으로 분석하여 0.1V, 3min의 전착조건으로 최적화하였다. 전기 촉매제로써의 PB의 특성을 확인하기 위하여 ITO 전극만을 사용한 전기화학적 검출기와 비교하였으며 본 연구에서 제안된 검출기의 감도가 20배정도 더 좋다는 것을 확인하였다.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1538-1539
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• 2007

모세관 전기 영동법을 이용한 전기화학적 검출기로 환경호르몬을 분리, 검출하는 연구를 수행하였으며 여러 가지 전극들간의 감도를 포함한 경제성과 효율을 비교하였다. 검출기에 사용된 전극으로는 Indium Tin Oxide (ITO) 전극과 bare ITO 전극 위에 Prussian blue (PB) 용액을 전착한 전극이 사용되고 검출기는 3전극을 사용하는 형식으로 제작하였다. PB전극이 사용된 검출기를 이용하여 비스페놀 A를 측정한 결과, bare ITO 전극을 사용한 검출기보다 우수한 민감도를 얻었다.

• Journal of the Korean Electrochemical Society
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• v.12 no.4
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• pp.329-334
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• 2009

This study is to develop a fuel cell system applicable to an in situ NMR (Nuclear magnetic resonance) diagnosis. The in situ NMR can be used in real time monitoring of various reactions occurring in the fuel cell, such as oxidation of fuel, reduction of oxygen, transport phenomena, and component degradation. The fuel cell for this purpose is, however, to be operated in a specifically designed tubular shape toroid cavity detector (TCD), which constrains the fuel cell to have a tubular shape. This may cause difficulties in effective mass transport of reactants/products and uniform distribution of assembly pressure. Therefore, a new flow field designed in a particular way is necessary to enhance the mass transport in the tubular fuel cell. In this study, a tubular-shaped close-type flow field made of non-magnetic material is developed. With this flow field, oxygen is effectively delivered to the cathode surface and the produced water is readily removed from the membrane-electrode assembly to prevent flooding. The resulting DMFC (direct methanol fuel cell) outperforms the open-type flow field and exhibits $36\;mW/cm^2$ even at room temperature.

• Korean Journal of Food Science and Technology
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• v.34 no.6
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• pp.998-1001
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• 2002

Micro-LC method for the quantitative determination of hydrogen peroxide in foods has been established. This method was carried out on cation-exchange resin gel column using distilled water as mobile phase with 50 mM sodium sulfate as electrolyte. The detection was performed with an electrochemical detector (ECD) at 0.6 voltage. Under this analytical condition, the recovery rates of hydrogen peroxide in tomato and lemon were 98.3 and 97.4%, respectively. Among 28 food types, hydrogen peroxide concentrations were 0.6, 0.5, 1.9, 0.9, 0.5, 0.6, 0.9, 0.8, and 0.4 ppm in banana, peach, orange, strawberry, pepper, onion, cucumber, burdock, and egg plant, respectively, Whereas none was detected in remaing 19 samples.

• Journal of the Korean Electrochemical Society
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• v.12 no.4
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• pp.335-341
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• 2009

Organic-inorganic hybrid sol-gel matrices were used as hosts for chloro (5, 10, 15, 20-tetraphenylporphyrinato) cobalt (III) (Co[TPP]Cl), a known ionophore for nitrite. The sol-gel precursor was prepared by the reaction of (3-isocyanopropyl) triethoxysilane with 1,4-butanediol. An appropriate amount of the anion-exchanger, tridodecylmethylammonium chloride (TDMAC) and the plasticizer, tributylphosphate (DBP) were used as membrane additives. On mixing with an acidic catalyst, the sol-state precursors slowly gelled, yielding a membrane in which the active components, Co[TPP]Cl and TDMAC, were encapsulated. The performances of the sol-gel membrane-based electrodes were compared to those of Co[TPP]Cl-based poly(vinyl chloride) (PVC) membrane electrodes. Membranes with a molar ratio of Co[TPP]Cl: TDMAC (1 : 0.1) showed reasonable response slopes toward nitrite. The response slopes were typically 53 mV/decade between $10^{-5.4}$ and $10^{-1.0}\;M$. Selectivities toward nitrite over hydrophilic and small anions such as chloride were somewhat inferior to those observed with PVC-based membranes, but selectivities over lipophilic anions were quite similar. Reduced asymmetry potentials due to protein adsorption were found to occur with the sol-gel matrix relative to PVC-based films when the sensors were employed as a detector in flow-through configuration.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.2
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• pp.127-133
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• 1997

Lithium remains the most widely used therapeutic agent for bipolar affective disorder, particularly mania. Although many investigators have studied the effects of lithium on abnormalities in monoamine neuro-transmitter as a pathophysiological basis of affective disorder, the action mechanism of lithium ion remains still unknown. To explore the action mechanism of lithium in the brain, we examined the effects of lithium on the extrasynaptosomal concentrations of catecholamines and their metabolites. Synaptosomes were prepared from the rat forebrains and assays of catecholamines and metabolites were made using HPLC with an electrochemical detector. Lithium of 1mM decreased the extrasynaptosomal concentrations of NE from the control group of $3.07{\pm}1.19$ to the treated group of $0.00{\pm}0.00$ (ng/ml of synaptosomal suspension) but not that of DHPG. It can be suggested that lithium increases synaptosomal uptake of NE. Increased intraneuronal uptake of NE would decrease neurotransmission and extraneuronal metabolism of NE. Because increased brain NE metabolism and neurotransmission have been suggested as important components in the pathophysiology of bipolar affective disorder, especially mania, lithium-induced increase of intraneuronal NE uptake can be suspected as an action mechanism of therapeutic effect of lithium in manic patient, possibly in bipolar affective disorder.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.04a
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• pp.100-103
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• 2003

Signal detection technologies such as fluorescence, charge and electrochemical detection used in the monolithic capillary electrophoresis system to convert the biochemical reaction into the electrical signal. The fluorescence detection using photodiodes that measure fluorescence emitted from eluting molecules is widely used for the monolithic capillary electrophoresis system. In this paper, in order to fabricate a photosensor has the increased sensitivity, we investigated on the sensitivity of general type and p-i-n type diode. The p-i-n diode has higher sensitivity than photodiode. Considering these results, we fabricated p-i-n diodes on the high resistive$(4k{\Omega}{\cdot}cm)$ wafer into rectangle and finger pattern and compared internal resistance of each pattern. The internal resistance of p-i-n diode can be decreased by the application of finger pattern has parallel resistance structure from $571{\Omega}$ to $393{\Omega}$.