• Title/Summary/Keyword: 전위성

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Membrane Potential across Porous Anion-Exchange Membranes in Electrolyte Solution (전해질용액에서의 다공성 음이온교환막을 통한 막전위)

  • ;;Kiyono, Ryotaro;Tasaka, Masayasu
    • Proceedings of the Membrane Society of Korea Conference
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    • 1997.04b
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    • pp.21-22
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    • 1997
  • 최근의 이온교환막은 종래의 양이온교환막의 표면에 polycation 등의 얇은 층을 덧붙인 다층막(multi-layer membrane)의 형태가 많이 이용되고 있으며, 정전기적 반발력의 차 등을 이용하여 원자가가 다른 이온들간의 투과성에 차를 부여하기 위하여 이용되고 있다. 이 때문에 polycation막을 통한 1가 이온과 2가 이온의 투과성을 연구하는 것은 우수한 이온교환막을 제작하는것 이상으로 중요하다. 본 연구에서는 고정전하농도(fixed charge density, $\Phi$ X)가 낮은 다공성 저전하음이온교환막을 제작하여, 양측에 대이온(counterion)은 같고 복이온(co-ion)이 다른 전해질용액을 두었을 경우에 관찰되는 막전위를 측정하였다. 이를 토대로 음이온교환막을 통한 막전위의 농도의존성에 관하여 검토하였으며, 비평형열역학(non-equilibrium thermodynamies)에 기초한 이론적 모델을 도입하여 실험치와 비교, 해석하였다.

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Nondestructive Techniques for Characterization of Microstructural Evolution during Low Cycle Fatigue of Cu and Cu-Zn Alloy (Cu와 Cu-Zn 합금의 저주기피로 동안 발달한 미세조직 평가를 위한 비파괴기술)

  • Kim, Chung-Seok;Jhang, Kyung-Young;Hyun, Chang-Young
    • Journal of the Korean Society for Nondestructive Testing
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    • v.31 no.1
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    • pp.32-39
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    • 2011
  • The object of this study is to evaluate and discriminate nondestructively the dislocation substructures of Cu and Cu-Zn alloy subjected to the low-cycle-fatigue. The ultrasonic wave velocity, electrical resistivity and positron annhilation lifetime(PAL) were measured to the nondestructive testing. Cyclic fatigue test of Cu and Cu-Zn alloy with much different stacking fault energies was conducted and the correlations between dislocation behavior and nondestructive parameters were studied. Dislocation cell substructure was developed in Cu, while planar array of dislocation structure was developed in Cu-35Zn alloy only increasing dislocation density with fatigue cycles. Decrease in ultrasonic wave velocity, increase in electrical resistivity and PAL were shown because of the development of lattice defects, dislocations and vacancies, by cyclic fatigue at room temperature. In contrast to Cu-Zn alloy of the planar-array dislocation substructure showing continuous changes in the nondestructive parameters, it does not make any noticeable changes in the nondestructive parameters after the evolution of dislocation cell substructure in Cu.

Electrohydrodynamic Treatment of the Shape and Stability of Liquid Metal Ion Sources (액체금속 이온 소오스의 모양과 안정도에 대한 전자유체역학적 연구)

Study of the Stability of Brass Coated on Steel Cords with pH and Applied Constant Potential Changes in Aqueous Solutions by AC Impedance Measurements (교류임피던스 측정에 의한 수용액에서 pH와 일정공급전위 변화에 따른 강철심에 도금된 놋쇠의 안정성 연구)

  • Ko, Young Chun;Chung, Keun Ho
    • Analytical Science and Technology
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    • v.8 no.3
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    • pp.293-298
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    • 1995
  • The stability of brass coated on steel cords with pH and applied constant potential changes in aqueous solution has been investigated by AC impedance measurements. In solutions of the constant pH, as a applied constant potential is shifted to positive potential, the coating pore resistance is reduced. The fact indicates that as a applied constant potential is shifted to positive potential, the brass coated is dissolved more in solution. The stability of brass coated on steel cords decrease in the order pH=7.1 > pH=4.0 > pH=10.0. The above results are demonstrated by the data of scanning of electronic microscopy(SEM)/energy dispersive spectrometer(EDS).

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2-D Stress Analysis by a Dislocation Model (전위모델 을 이용한 2차원 응력해석)

  • 구인회
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.9 no.1
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    • pp.10-17
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    • 1985
  • A new method is suggested for the solution of plane elasticity problems. With use of the dislocation model in the crack problems, the basic scheme of this method is to find equilibrium Burgers vectors of dislocations which are distributed along the boundary of the first fundamental boundary value problems. The stress distribution in the region can be found by superposition of the contributions of each dislocation. The method is applied to three cases with known analytical solutions, and to a V-notched specimen under uniaxial tension. The numerical results are compared with other available solutions. This method is effective and simple in its use, compared with other numerical methods. The method also provides very accurate solutions in the region except near the boundary where the discretization error is significant. The extrapolation method is suggested for the stresses in the boundary region. Extensive application are also suggested for a general estimate of the computational efficiency of the method.

Event Related Potential and Neuropsychological Tests (사건 관계 전위와 신경심리 검사)

  • Lee, Sung-Hoon;Koo, Ae-Sook;Woo, Jong-Ho;Kim, Byung-Gun
    • Sleep Medicine and Psychophysiology
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    • v.1 no.1
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    • pp.76-86
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    • 1994
  • Objectives: This research was performed in order to observe the neuropsychological implication and functional anatomical source of event related potentials(ERP) by studying of correlations between event related potentials and neuropsychological tests. Methods: The latency and voltage of P100 of visual evoked potential (VEP), and N120 and P300 of event related potentials were studied in 56 patients and their correlations with neuropsychological tests were computed. Results: The tests showing significant correlation with latency P100 were visual continous performance test(VCPT) and contingent continous performance test(CCPT) without any significant correlation with voltage of P100. In latency of N120 category test and verbal IQ of KWIS showed significant correlation, and in voltage of N120, finger tapping test, VCPT, CCPT and digit symbol test displayed significant correlations. The latency of P300 had significant correlation with trail making A test and Stroop test. In the voltage of P300 significant correlations were shown with trail making B test, digit symbol test and Wechsler memory scale, finger tapping test, stroop test, VCPT and CCPT. Conclusion : N120 may be considered to reflect the function of medial frontal lobe and P300 may be considered to be developed from the subcortical connection of medial temporal lobe, hippocampus, thalamus, basal ganglia and medial frontal lobe.

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Investigation on optimum cavitation-erosion protection potential of anodized 5083-H321 Al alloy in sea water (양극산화 처리된 5083-H321 알루미늄 합금의 해수 내 캐비테이션-침식 방지를 위한 최적 방식전위 규명)

  • Yang, Ye-Jin;Jang, Seok-Gi;Kim, Seong-Jong
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2016.11a
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    • pp.143-143
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    • 2016
  • 알루미늄 합금은 내구성과 내식성이 우수할 뿐만 아니라 다양한 표면개질을 통해 그 표면 특성을 더욱 향상시킬 수 있다. 특히 Al-Mg계 5083-H321 Al 합금의 경우 가공성 및 용접성이 우수하여 선체 재료로 널리 이용되는데, 이는 선체중량의 경량화가 가능하여 연료비 절감과 빠른 선속 등 다양한 이점을 지니기 때문이다. 그러나 선속의 고속화에 따라 선체에 가해지는 유체충격이 증가하고 정압 저하에 기인하여 캐비테이션-침식 손상이 증가할 뿐만 아니라 해수환경 특성 상염소이온의 존재로 부식이 가속화되는 등 침식 및 부식의 시너지효과로 손상은 크게 증가한다. 이에 대한 방지대책으로 다양한 표면개질 기법이 제안되고 있으나 강한 충격압이 동반된 캐비테이션 침식-부식 복합 손상 환경에서는 표면처리만으로는 불가능할 수 있다. 따라서 본 연구에서는 양극산화된 5083-H321을 대상으로 캐비테이션 환경 하에서 일정 전위를 인가하여 침식-부식 손상이 최소화되는 최적전위를 규명하고자 한다. 이를 위해 먼저 분극 실험을 통해 재료의 전기화학적 거동을 바탕으로 임의의 전위를 선정하고 해당 전위를 인가한 상태에서 캐비테이션 실험을 실시하였다. 이때 분극실험과 캐비테이션-전기화학 복합실험 모두 $25^{\circ}C$의 해수에서 실시하였으며, 전기화학적 분극실험은 유효면적이 $3.24cm^2$인 시편에 2 mV/s의 분극속도로 0 ~ -3 V 까지 인가하였고, Ag/AgCl 기준전극과 백금대극을 사용하였다. 캐비테이션-전기화학 복합 실험은 정전위를 인가한 상태에서 $30{\mu}m$의 진폭으로 20분간 실시하였으며, 혼팁과 시험편 사이의 거리는 1 mm로 일정하게 유지하였다. 실험 후 표면 손상의 정량적 분석을 위해 인가된 전위별 전류밀도를 비교하고, 무게감소량을 측정하였으며, 손상특성 분석을 위해 3D현미경과 주사전자현미경(SEM)을 통해 표면을 분석하였다.

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A Study on Development of Cathodic Protection on Underground Pipeline Measuring System (매설배관의 방식전위 측정시스템 개발에 관한 연구)

  • Kim, Jin-Jun;Seo, Min-Sung;Kim, Dong-Kyun
    • Journal of the Korean Institute of Gas
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    • v.18 no.5
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    • pp.66-71
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    • 2014
  • Gas pipelines are the core facilities in the gas facilities and the most pipelines are buried underground and are exposed to the risk of corrosion caused by the soil characteristics and the environmental impact. The anti-corrosion potential and the corrosion status of the underground pipelines are measured periodically in accordance with the relevant laws and regulations. A study on the cathodic protection measurement system was carried out in order to solve the problems of the conventional measurement system. This paper describes the survey on the standards and the specifications of the cathodic protection measurement and the the reference electrode to meet the relevant regulations, and the development of the measuring circuit and the data transmission module to build the cathodic protection measurement system. This study verified the field applicability through the testing of the developed prototype and investigated on the problems of the previous studies and the future research and development direction.

ELECTROPHYSIOLOGICAL AND MORPHOLOGICAL CHARACTERISTICS OF FACIAL NUCLEUS IN RAT (흰쥐 안면신경핵 세포의 전기생리학적 및 형태학적 특성)

  • Choi, Byung-Ju;Cho, Jin-Hwa;Bae, Yong-Chul;Kim, Young-Jin
    • Journal of the korean academy of Pediatric Dentistry
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    • v.27 no.3
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    • pp.400-409
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    • 2000
  • This study used in vivo intracellular and extracellular field potential recording to evaluate the intrinsic membrane properties and connection pattern within facial nucleus. 1. There were four subdivisions of medial, intermediate, lateral, and dorsolateral in facial nucleus. 2. Principal cells in the facial nucleus was recorded from and filled with neurobiotin in anesthetized rats. The extent of their dendrites and the characteristics of cell body were examined. 3. Principal cells had a large amplitude action potential and afterhyperpolarization was followed a single action potential. 4. The response from facial motonucleus to electrical stimulation of the facial nerve was mainly a monophasic wave, with a latency of 1 msec, which was assumed to reflect antidromic activation of facial motoneurons. In some of rats the response in addition showed late components at a latency of about 7-8 msec, but its amplitude was small. 5 Most of cells exhibited accommodation of spike discharge upon depolarization of membrane by 0.8 nA for 400 ms. Our results support the hypothesis that there normally are weak connections between different parts of the facial motonucleus to explain pathophysiology of hemifacial spasm and facial naive paralysis.

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Experimental investigation on the dependence of the difference between plasma potential and floating potential on plasma density in cylindrical Langmuir probes (원통형 량뮤어 프로브에서의 플라즈마 전위와 부유 전위의 플라즈마 밀도 의존성 연구)

  • Chung, Chin-Wook;Lee, Won-Ki
    • Proceedings of the KIEE Conference
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    • 2004.07c
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    • pp.1967-1968
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    • 2004
  • 최근 F. F. Chen 에 의하면 [F.F. Chen and D. Arnush, Phys. Plasmas, 8, 5051(2001)], 원통형 량뮤어 탐침의 경우 플라즈마 전위와 부유 전위의 차(${\triangle}V_{pf}$) 가 상수가 아니며 플라즈마 밀도에 따라 달라지고 밀도가 아주 높은 경우 즉 쉬스가 탐침의 반경보다 아주 얇은 경우에는 ${\triangle}V_{pf}$ 는 평면 탐침과 같이 상수가 된다는 것을 이론적으로 보였다. 이에 본 연구에서는 아르곤 유도 결합 플라즈마에서 원통형 량뮤어 탐침을 사용하여 F. F. Chen의 이론적인 결과를 실험으로 검증하였으며 F.F. Chen 의 이론적인 결과와 잘 일치하였다.

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