• 한국통신학회논문지
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• 제32권3A호
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• pp.319-323
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• 2007

본 논문에서는 50-1000 MHz의 주파수 범위에서 전력과 임피던스의 표준을 이용하여 RF전압을 자동으로 정밀 측정을 하였다. RF-DC차를 결정하기 위하여 동축형 미소열량계와 자동 회로망 분석기가 이용되었으며, 총불확도는 약 1 % 이다. 써미스터 마운트의 실효효율과 열전압 변환기의 RF-DC차를 측정하기 위하여 HP 컴퓨터와 Commodore 컴퓨터, 그리고 IEEE-488 인터페이스 버스를 이용하고, 측정하는 전체과정이 자체 개발한 프로그램에 의해 자동으로 수행되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.121-124
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• 1998

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li secondary battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PVDF electrolytes as a function of a mixed ratio. Polyvinylidene(PVDF) based polymer electrolyte films were prepared by thermal gellification method of preweighed PVDF, plasticizer and Li salt. The conductivity of PVDF electrolytes was 10$\^$-3/S/cm. 25PVDFPC$\_$10/EC$\_$10/LiClO$_4$ electrolyte shows the better conductivity of the others. 25PVDFPC$\_$10/EC$\_$10/LiClO$_4$electrolyte remains stable up to 4.7V vs. Li/Li$\^$+/. Steady state current method and ac impedance used for the determination of transference numbers in PVDFD electrolyte film. The transference number of 25PVDFPC$\_$10/EC$\_$10/LiClO$_4$electrolyte is 0.58.

• 전기학회논문지P
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• 제63권4호
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• pp.322-326
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• 2014

Recently, the LOE(loss of excitation) incidents are occurred in domestic synchronous generator frequently, the synchronous generator protection system has been much attention for the LOE protection of the incidents that threats synchronous generators and power systems. This paper was showed the characteristics and practices of distance relay that widely used LOE protection relaying in generator. Firstly, the operating characteristics and the impedance locus for LOE of the generator protection were introduced. Even if the conventional simulation program is used for modeling, but it is difficult to implement a LOE modeling and simulation of synchronous generator. So, the LOE relay operation data collected from thermal power plant and nuclear power plant in real fields were analyzed. By reviewing the applications of GE Mho relays, the reliability of LOE for synchronous generator protection in domestic were improved.

• Journal of Electrochemical Science and Technology
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• 제9권1호
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• pp.1-8
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• 2018

The effect of mixing ratio on the corrosion protection of carbon steel coated by a film composed of poly(vinylidene) fluoride (PVDF) and poly(methyl methacrylate) (PMMA) was examined using electrochemical impedance spectroscopy. Surface crystallization behavior and thermal properties of the PVDF/PMMA coated carbon steel were evaluated using polarized optical microscopy and differential scanning calorimetry, respectively. A Maltese cross-pattern spherulite crystal was observed in the PVDF/PMMA coating film, which became more apparent with increasing PVDF content. The highest corrosion protection performance was achieved with 60 wt.% PVDF-coated carbon steel, and delamination and corrosion reactions were observed for 20 wt.% PVDF-coated carbon steel. Further, corrosion protection performance with an amorphous/crystal mixture (PVDF/PMMA, 60/40 (w/w)) was better than those observed in the amorphous domain and the perfect-crystal domain of the PVDF/PMMA blended coating system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.374-377
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• 1999

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. This paper describes temperature dependence of conductivity, impedance spectroscopy, electrochemical properties of PVDF/PAN electrolytes as a function of a mixed ratio. PVDF/PAN based polymer electrolyte films were prepared by thermal gellification method of preweighed PVDF/PAN, plasticizer and Li salt. The conductivity of PVDF/PAN electrolytes was 10-3S/cm. 20PVDF5PANLiCIO$_4$PC$\sub$10//EC$\sub$10/ electrolyte shows the better conductivity of the others. 20P7DF5PANLiCI$_4$PC$\sub$10//EC$\sub$10/ electrolyte remains stable up to 5V vs. Li/Li$\^$+/. Steady state current method and ac impedance used for the determination of transference numbers in PVDF/PAN electrolyte film. The transference number of 20PVDF5ANLICIO$_4$/PC $\sub$10//EC$\sub$10/ electrolyte is 0.48

• 한국산학기술학회논문지
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• 제14권12호
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• pp.6098-6105
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• 2013

본 연구에서는 해수용 열교환기 적용을 위한 열분사코팅의 종류에 따른 부식특성 및 열전도 성능을 조사하기 위해 실험이 수행되었다. 코팅은 아연과 알루미늄을 열분사코팅한 뒤 실리콘 및 에폭시 수지를 추가 도포한 시편을 선정하였다. 코팅의 부식특성 변화를 관찰하기 위하여 사이클릭 선도변화 측정 및 SEM촬영을 이용하였다. 시편의 열전도 성능을 측정하기 위해서 레이저 확산법을 이용하여 열전도도를 비교하였으며 추가도포를 실리콘으로 한 경우 3 ~ 4% 에폭시로 한 경우 70 ~ 75%의 열전도도 하락이 발생하였다.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2226-2230
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• 2007

As a cathode material of lithium rechargeable batteries, charged Li[Co0.1Ni0.15Li0.2Mn0.55]O2 electrodes, which were aged thermally at 25 oC and 90 oC respectively, were characterized by means of charge/discharger, impedance spectroscopy, and X-ray diffraction. The discharge capacity diminution of the electrodes aged at 25 oC and 90 oC for 1 week was 4% and 23%, respectively. The cell aged at 25 oC was recovered on cycling. However, the capacity loss after ageing at 90 oC was not recovered in a subsequent cycling test, which demonstrates that the reaction occurring during ageing at 90 oC is irreversible. A significant impedance increase of aged electrode at 90 oC is associated with irreversible capacity loss. The structural changes including phase transformation were not detected by XRD analysis, because it could be due to out of detection limit. After ageing, impedance was slightly decreased during subsequent cycling test. It could be explained the cyclic performance of aged sample is stable. The thermal stability was not deteriorated by ageing even at the high temperature of 90 oC.

• Journal of Advanced Marine Engineering and Technology
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• 제39권5호
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• pp.536-541
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• 2015

Copper has been used extensively as an electric wire or as a base material in various types of machineries owing to its good electrical and thermal conductivity and good fabricating property, as well as its good corrosion resistance compared to iron. Furthermore, the copper-nickel alloy has significant corrosion resistance in severely corrosive environments. Although, cupro-nickel alloy shows better corrosion resistance than the brass and bronze series, this alloy also corroded in severely corrosive environments, including aggressive chloride ions, dissolved oxygen, and condition of fast flowing seawater. In this study, and annealing treatment at various annealing temperatures was carried out on the cupro-nickel (Cu-10%Ni) alloy, and the effects of annealing were investigated using electrochemical methods, such as measuring the polarization and impedance behaviors under flowing seawater conditions. The corrosion resistance increased by annealing compared to non heat treatment in the absence of flowing seawater. In particular, the sample annealed at $200^{\circ}C$ exhibited the best corrosion resistance. The impedance in the presence of flowing seawater showed higher values than in the absence of flowing seawater. Furthermore, the highest impedances was observed in the sample annealed at $800^{\circ}C$, irrespective of the present of flowing seawater. Consequently, the corrosion resistance of cupro-nickel (Cu-10%Ni) alloy in a severely corrosive environment can be improved somewhat by annealing.

• 한국정보전자통신기술학회논문지
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• 제10권6호
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• pp.487-495
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• 2017

무전극 램프의 열특성은 램프의 설계와 성능을 결정하는 주요 요소 중 하나이다. 커플러는 열에 의해 임피던스 특성이 변화하며 그 사용온도가 보통 약 $150^{\circ}C$ 이내이다. 본 연구에서는 지금까지 논외였던 $150^{\circ}C$ 이상의 온도에 커플러가 노출되었을 때의 현상에 대해 관찰하였다. 벌브의 안쪽 내관과 커플러와의 이격거리가 다른 두 종류의 커플러 A와 커플러 B에 대해 방열 조건과 열 차단 조건을 달리하여 전기적 특성, 열적 특성, 광학적 특성과의 연계성 및 열화 특성 등을 분석하였다. 우선 시스템의 임피던스를 구하여 이를 통한 전기적 특성을 분석하는 기준으로 삼았다. 두 종류의 커플러의 직경차는 1mm이며, 실험 결과에서 커플러의 직경이 1mm 작아서 발생하는 자계강도의 손실을 상쇄할 수 있는 조건을 찾을 수 있었다. 따라서 이러한 결과를 토대로 커플러가 약 $200^{\circ}C$의 고온에 노출될 때, 이에 대응하는 효율적인 설계 방안을 제시하였다.

• 한국전기전자재료학회논문지
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• 제30권5호
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• pp.331-337
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• 2017

Thermal batteries, reserve power source, is activated by melting of molten salt at the temperature range of $350{\sim}550^{\circ}C$. To immobile the molten state electrolyte when the thermal battery is activated, the binder must be added in electrolyte. Usually, molten salts include 30~40 wt% of MgO binder to ensure electrical insulation as well as safety. However, the conventional MgO binder tends to increase ionic conductive resistance and thus the inclusion of the binder increases the total impedance of the battery. This paper mainly focused on the study of yttria stabilized zirconia (YSZ) as an alternative binder for molten salt. The chemical stability between the molten salt and YSZ is measured by XRD and DSC. And the sufficient path for ionic conduction on molten salt could be confirmed by the enhanced wetting behavior and the enlarged pore size of YSZ. The electrochemical properties were analyzed using single cell tests so that it showed the outstanding performance than that using MgO binder.