• 제목/요약/키워드: reference electrode

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$CO_{2}$ sensing characteristics of solid electrolyte gas sensor with the sensing membrane prepared by the mixture of alkali metal carbonate and binder (알카리 금속 탄산염과 결착제의 혼합물을 감지물질로 하는 고체전해질 가스센서의 $CO_{2}$ 감응 특성)

  • Chai, Yu-Sug;Song, Kap-Duk;Kang, Bong-Hwi;Seo, Moo-Gyo;Lee, Duk-Dong
    • Journal of Sensor Science and Technology
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    • v.7 no.2
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    • pp.111-116
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    • 1998
  • The simple solid electrolyte carbon dioxide sensor with heaters were fabricated by using Li ionic conductor. Two Au electrodes were used for the reference and sensing electrode respectively. Two types of gas sensors, type ( I ) and type (II), were fabricated. Type ( I ) sensor was fabricated by the method of melting and crystallizing alkali metal carbonate at the temperature of $420{\sim}500^{\circ}C$. The sensing membrane of type (II) sensor was formed by the printing method on sensing electrode after metal carbonate was mixed with binder. The response characteristics of sensors fabricated for the carbon dioxide were investigated for a range of $CO_{2}$ concentration from 950 ppm to 9,950 ppm at operating temperature $420^{\circ}C$. Type ( I ) sensor and type (II) sensor showed the sensitivity of 62 mV/decade and 65 mV/decade respectively. The emf/decade of type (II) sensor tested at $420^{\circ}C$ almost followed the theoretical value of Nernst's equation and showed stable response characteristics with the fast response time of $15{\sim}20$ sec. Also type (II) sensor showed excellent stability and reproduction properties for 60 days.

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Effect of Vinylene Carbonate as an Electrolyte Additive on the Electrochemical Properties of Micro-Patterned Lithium Metal Anode (미세 패턴화된 리튬금속 전극의 Vinylene Carbonate 첨가제 도입에 따른 전기화학 특성에 관한 연구)

  • Jin, Dahee;Park, Joonam;Dzakpasu, Cyril Bubu;Yoon, Byeolhee;Ryou, Myung-Hyun;Lee, Yong Min
    • Journal of the Korean Electrochemical Society
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    • v.22 no.2
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    • pp.69-78
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    • 2019
  • Lithium metal anode with the highest theoretical capacity to replace graphite anodes are being reviewed. However, the dendrite growth during repeated oxidation/reduction reaction on lithium metal surface, which results in poor cycle performance and safety issue has hindered its successful implementation. In our previous work, we solved this problem by using surface modification technique whereby a surface pattern on lithium metal anode is introduced. Although the micro-patterned Lithium metal electrode is beneficial to control Li metal deposition efficiently, it is difficult to control the mossy-like Li granulation at high current density ($>2.0mA\;cm^{-2}$). In this study, we introduce vinylene carbonate (VC) electrolyte additive on micro patterned lithium metal anode to suppress the lithium dendrite growth. Owing to the synergetic effect of micro-patterned lithium metal anode and VC electrolyte additive, lithium dendrite at a high current density is dense. As a result, we confirmed that the cycle performance was further improved about 6 times as compared with the reference electrode.

A Study on the Development of Remotely CP Potential Measuring Method by using Vehicle (차량을 이용한 원격전위 측정방법 개발에 관한 연구)

  • Ryou, Young-Don;Jo, Young-Do;Kim, Jin-Jun;Seo, Min-Sung
    • Journal of the Korean Institute of Gas
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    • v.20 no.5
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    • pp.64-71
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    • 2016
  • According to the urban gas business law, electrical corrosion prevention measures shall be installed to the buried gas pipelines and the pipe-to-soil potentials should be measured at the test box at least once a year. Most of the test boxes installed in urban area are usually located on the road where the vehicle travels, therefore, it is difficult to measure the CP potentials at the test boxes. That is, we need traffic control when carrying out the measurement of the CP potentials on daytime when the traffic is heavy, or we have to measure the potentials in the late night when the traffic is light. To solve these difficulties, we have studied remotely CP potential measuring method by using the patrol car. We have installed solid reference electrodes and data loggers under the test boxes on the site and received the CP potentials from the data loggers when the vehicle moves. It was difficult to send and receive the data because the data logger was located under the ground. We have applied 3 different method including 2 antenna systems to achieve best effective way in receiving the data. We have found the remote CP measuring method by using a car can save more 20 times of measuring time than conventional measuring methods.

Determination of Chloramphenicol by Differential Pulse Polarography (미분 펄스 폴라로그래피에 의한 Chloramphenicol의 정량분석)

  • Younghee Hahn;Jung-Sun Jeon
    • Journal of the Korean Chemical Society
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    • v.36 no.4
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    • pp.552-557
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    • 1992
  • Chloramphenicol was studied by differential pulse polarography (DDP). A reduction peak which is dependent on pH of the solution appeared in the voltage range between zero and -1.50 volt vs. Ag/AgCl (sat. KCl) reference electrode. A plot of peak potentials (Ep) measured at room temperature (20$^{\circ}C$) vs. pH of the chloramphenicol solutions showed linear relationship changing slope (Ep/pH) at pH 8.9. The slope was -59.7 mV/pH in pH 2.7∼8.9 and -24.3 mV/pH in pH 8.9∼11.2, respectively. A log plot of peak currents (ip) vs. concentrations showed a linearity at the concentrations between 4.8 ${\times}$ 10$^{-7}$ M and 6.2 ${\times}$ 10$^{-5}$ M (0.16 ppm∼20 ppm) chloramphenicol in pH 8.0 ammonium buffer. Between the DPP method and the reference method measuring absorbance at 278 nm, the correlation coefficient was 0.996, which means an excellent linearity. The DPP method was able to detect degradation products of chloramphenicol in mild alkaline solution (pH = 8.0) more distinctly than the spectrophotometric method.

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A new nano-composite carbon ink for disposable dopamine biosensors (나노컴포지트 카본 잉크가 전착된 일회용 도파민 바이오센서)

  • Dinakaran, T.;Chang, S.-C.
    • Analytical Science and Technology
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    • v.29 no.1
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    • pp.35-42
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    • 2016
  • A new nano-composite carbon ink for the development of disposable dopamine (DA) biosensors based on screen-printed carbon electrodes (SPCEs) is introduced. The method developed uses SPCEs coupled with a tyrosinase modified nano-composite carbon ink. The ink was prepared by an “in-house” procedure with reduced graphene oxide (rGO), Pt nanoparticles (PtNP), and carbon materials such as carbon black and graphite. The rGO-PtNP carbon composite ink was used to print the working electrodes of the SPCEs and the reference counter electrodes were printed by using a commercial Ag/AgCl ink. After the construction of nano-composite SPCEs, tyrosinase was immobilized onto the working electrodes by using a biocompatible matrix, chitosan. The composite of nano-materials was characterized by X-ray photoelectron spectroscopy (XPS) and the performance characteristics of the sensors were evaluated by using voltammetric and amperometric techniques. The cyclic voltammetry results indicated that the sensors prepared with the rGO-PtNP-carbon composite ink revealed a significant improvement in electro-catalytic activity to DA compared with the results obtained from bare or only PtNP embedded carbon inks. Optimum experimental parameters such as pH and operating potential were evaluated and calibration curves for dopamine were constructed with the results obtained from a series of amperometric detections at −0.1 V vs. Ag/AgCl. The limit of detection was found to be 14 nM in a linear range of 10 nM to 100 µM of DA, and the sensor’s sensitivity was calculated to be 0.4 µAµM−1cm−2.

A Study on the Transient Ground Impedance Modeling for Rod-type Grounding Electrodes by Frequency and Time Domain Characteristic Tests (주파수 및 시간영역 특성시험에 의한 봉형 접지전극의 과도 접지임피던스 모델링에 관한 연구)

  • Kim, Jong-Uk;Kim, Kyung-Chul;Shin, Pan-Seok;Choi, Jong-Ki;Choi, Sun-Kyu;Kim, Dong-Myung
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.24 no.2
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    • pp.133-141
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    • 2010
  • Grounding system insures a reference potential point for electric devices and also provides a low impedance path for fault currents in the earth. The ground impedance as function of frequency is necessary for determining its performance since fault currents could contain a wide range of frequencies. Copper and concrete rod electrodes are the most commonly used grounding electrode in electric distribution systems. In this paper, the ground impedance of copper and concrete rods has been measured by frequency and time domain characteristic tests. An equivalent transfer function model of the ground impedance is identified from the measured values by using ARMA method and evaluated by comparing conventional grounding impedances.

A Study on a Shielding Effect of the Messenger Wires in Distribution Lines (배전선로에서의 조가선 차폐 효과 연구)

  • Kim, In-Soo;Han, Woong;Yeo, Sang-Min;Kim, Chul-Hwan;Weon, Bong-Ju;Lim, Yong-Hun
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.58 no.3
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    • pp.431-436
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    • 2009
  • As the telecommunication lines bring into widespread use, one of the most important aspects related to power distribution systems is effectively to evaluate the effect on the telecommunication lines from power lines. One of the efficient methods to evaluate the effect is to measure the induced voltage of a telecommunication line as a result of a ground-loop. If the power lines cause high induced voltage, the ground reference in the telecommunication lines is no longer a stable potential, so signals may ride on the noise. A ground loop is common wiring conditions where a ground current may take more than one path to return to the grounding electrode at the arrangement between the power lines and telecommunication lines. When a multi-path connection between the power lines and telecommunication line circuits exists, the resulting arrangement is known as a ground loop. Whenever a ground loop exists, there are potential for damages or abnormal operations of the telecommunication lines. The power lines can induce the voltage on the communication line. The effects can be calculated by considering the inductances and capacitances. However, if we assume that there are only power lines, it doesn't have a practical meaning because there are conductors with other purpose in the neighborhood of the lines. If we consider that case, we need more complex system. Therefore we suggest more complex system considering the conductors with other purpose in the neighborhood of the lines. The neutral wires and the overhead ground wires are considered for calculating the induced voltage. We assume that there are the messenger wires beside the power line as a result of increased use of them. The main purpose of this paper is a study on a shielding effect of messenger wires in the distribution lines. EMTP(Electro-Magnetic Transients Program) program is used for the induced voltage calculation.

Redox Reaction Mechanisms of Thorium (IV) Complexes with Crown Ethers in Dimethylsulfoxide (디메틸술폭시드용매중에서 Thorium (IV)-Crown Ether 착물의 산화-환원 반응메카니즘)

  • Jung, Hak-Jin;Jung, Oh-Jin;Suh, Hyouck-Choon
    • Journal of the Korean Chemical Society
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    • v.31 no.3
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    • pp.250-257
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    • 1987
  • The electrical conductances for the thorium (IV) complexes with crown ethers have been measured in DMSO, and water solvents, and the oxidation-reduction reaction mechanisms, electron number and diffusion coefficients in the reversible reduction process have been examined by polarography and cyclic voltammography. The dissociation mole ratio of $Th^{4+}$ and nitrate ion are 1:1 and in aprotic solvent, and 1:4 in protic solvent like as water. The limiting molar conductances of all complexes in aprotic solvent have been found to be in the range of $92.2{\times}159$ $ohm^{-1}cm^2mol^{-1}$. In aprotic solvent, DMSO, the reduction of each complex is reversible by one electron reduction of one step, and the range of diffusion coefficients is obserbed to be $5.83\;10^{-6}{\sim}6.90{\times}10^{-6}$. The complexes which have reduction step were hydrolyzed above at 1.8volt with reference saturated calomel electrode, generating the hydrogen gas. The reaction mechanisms of thorium (IV)-crown ether complexes appear as follows. ${Th_m(IV)L_n(H_2O)_x(NO_3)_{4y}}_=^{DMSO} {\overline{{Th_m(IV)L_n(H_2O)_x(NO_3)_{4y-1}}}^+ + NO_3-$

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A Study on the Development of a Control and Monitoring System for Impressed Current Corrosion Protection (선박용 차세대 외부전원방식 제어 및 감시 시스템 UNIT 개발)

  • Kim, Y.B.;Kim, B.Y.;Suh, J.H.;Kim, J.W.
    • Journal of Power System Engineering
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    • v.10 no.2
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    • pp.104-110
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    • 2006
  • Corrosion has been around for all of recorded history. Cathodic protection is the electrical solution to the corrosion problem. Corrosion is not exactly a new topic. It has been around since the beginning of time. Corrosion is simply the loss of material resulting from current leaving a metal, following through a medium, and returning to the metal at a different point. Corrosion takes many forms and has various names, such as oxidation, rust, chemical, and bacteria action. Regardless of the agent, all corrosion is the result of electrical current flow. Various methods are used to treat corrosion or to try to prevent ti. Some of these include chemical treatment. coatings, and electrical current. Especially, proper impressed current can stop corrosive action on the protected surface. In this article, we introduce the Impressed Current Cathodic Protection (ICCP) Control and monitoring system developed by ourselves. The ICCP system is composed of a power supply, anode, reference electrode and controller. The main issue is to control the current flow on the desired value such that it is possible to force a metal to be more negative(cathodic) than the natural state. From the this process, we can achieve the cathodic protection. Of course, in the developed system, the necessary functions are possessed, such as remote control, monitoring of system fault detection etc. Some experimental results show the system performance and usefulness.

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A Comparison of EEG and Forearms EMG Activity depend on the Type of Smartphone when Inputting Text Messages (스마트폰 유형에 따른 문자 입력 시 뇌파 및 아래팔 근활성도 비교)

  • Lee, Hyoungsoo;Go, Gyeongjin;Kim, Jinwon;Park, Songyi;Park, Jiseon;Park, Jinri;Seok, Hyer;Yang, Gureum;Yang, Sieun;Yun, Gwangoh
    • Journal of The Korean Society of Integrative Medicine
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    • v.2 no.2
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    • pp.79-88
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    • 2014
  • Purpose: This study investigated the relationship between smartphone addiction propensities and compare muscle activity of the forearms and brain wave depend on the type of smartphone when inputting text messages. Method: We used an EMG to measure the change in muscle activity by attaching pads to the four muscles in both forearms of all 16 participants. We simultaneously conducted EEG measurements by observing the changes in alpha and beta waves recorded from electrode attached to both ears and the forehead of the participants. The participants had to input a given text using three different types of smartphones for ten minutes each. Result: The comparison of the EMG when inputting text involved a one way analysis of variance and the results showed that the iPad3 was highest for muscle activity followed by GALAXY Note2 and iPhone4. For EEG measurement, a one way analysis of variance was also used and the results showed iPhone4 was higest followed by GALAXY Note2 and finally iPad3 for EEG stress score. Conclusion: The results are thought to be used as reference data for smart phone users.