• Bulletin of the Korean Chemical Society
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• 제32권spc8호
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• pp.2911-2915
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• 2011

Efficient synthetic method for the preparation of ethyl 2-aryl-2,3-alkadienoates through Pd-catalyzed selective allenyl cross-coupling reactions of aryl iodides with organoindiums generated in situ from indium and ethyl 4-bromo-2-alkynoate was developed. The cyclization reaction of ethyl 2-aryl-2,3-alkadienoates catalyzed by $AuCl_3$ and AgOTf in the presence of AcOH or TfOH produced various ${\alpha}$-aryl ${\gamma}$-butenolides or ${\gamma}$-substituted ${\alpha}$-aryl ${\gamma}$-butenolides.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1887-1891
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• 2008

In this paper, we dealt with a partial discharge (PD) measurement method that has been accepted as an effective and non-destructive technique to estimate insulation performance of low-voltage induction motors. The PD measurement system consists of a coupling network, a low noise amplifier, and associated electronics. A shielded box was used to reduce environmental noise. Frequency characteristic of the coupling network was estimated by a sinusoidal signal input, and the low cut-off frequency of the coupling network was 1 MHz (-3 dB). Also, we carried out a calibration test for the PD measurement system. Sensitivity of the system was of 84 m$V_{max}$/pC between stator winding and enclosure. In application test on a low-voltage three phase induction motor (5 HP), we could detect 88 pC at AC 800 $V_{max}$.

• 전기학회논문지
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• 제62권2호
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• pp.213-218
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• 2013

In this study, epoxy/mica composite was prepared by mixing with mechanical stirrer together with homogenizer, and the effect of amino-type silane coupling agent was also studied. To reduce the viscosity without any decrement of other properties, 1,4-Butanediol diglycidyl ether (1,4-BDGE) as an aliphatic epoxy reactive diluent was introduced to the epoxy/mica composite in order to use as vanish for high voltage motor and generator stator winding. It was confirmed by scanning electron microscopy (SEM) observation that interfacial characteristics between organic epoxy and inorganic mica was modified by coupling agent treatment so that glass transition temperature increased, and tensile strength and electrical breakdown strength increased. The properties were estimated by Weibull statistical analysis and the ac electrical breakdown strength was 20.2% modified by treating silane coupling agent.

• 한국전자파학회논문지
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• 제26권10호
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• pp.895-906
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• 2015

본 논문에서는 모바일 충전회로를 대상으로 IEC 규격의 EFT/B(Electric Fast Transient and Burst) 내성 시험을 수행할 때 전달되는 신호를 예측할 수 있는 방법론 및 모델을 제안한다. EFT/B 신호는 모바일 충전회로가 충전 중인 상태에서 전달되기 때문에 교류전원 단에서 부터 부하 단까지의 신호전달특성을, 모바일 충전회로에 교류전원이 연결된 상태에서 알아야할 필요가 있다. 이를 위하여 간단한 CDN(Coupling-Decoupling Network)을 설계 제작하였으며, 이것을 이용하여 교류전원이 연결되어 있을 때와 연결되어 있지 않을 때의 두 가지 경우에 대해서 모바일 충전회로의 S-parameter를 VNA(Vector Network Analyzer)를 이용하여 측정하였다. 그 결과, 측정된 모바일 충전회로의 S-parameter 특성은 전원의 연결 유무와 거의 무관하였으며, 이것을 근거로 하여 모바일 충전회로만의 전달특성을, 전원이 연결되지 않은 상태에서, 적절한 인터페이스를 제작하여 측정하였다. 실제 EFT/B 신호 입출력의 전달함수를 구하여 S-parameter 측정의 정확성을 검증하였다. 이렇게 측정된 특성을 이용하여 모바일 충전회로의 EFT/B 신호가 전달되는 특성을 효과적으로 예측할 수 있었음을 보였다.

• 전기학회논문지P
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• 제59권1호
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• pp.40-46
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• 2010

DC link electrolytic capacitors are widely used in various PWM power converter system, such as adjustable speed driver(ASD) or DC/DC converter. Electrolytic capacitors, which is the most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. This objective of this paper is to propose a improvement method to detect the rise of equivalent series resistor(ESR) in order to realize the online failure prediction of electrolytic capacitor for DC link of PWM power converter. The ESR detection scheme is based on the determination of the electrolytic capacitor AC losses calculated from voltage/current measurement using AC coupling. Therefore, the preposed online failure prediction method has the merits of easy ESR computation and circuit simplicity compare with BPF method. Simulation results show the veridity of the proposed on-line ESR estimation method.

• 한국전기전자재료학회논문지
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• 제11권3호
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• pp.167-173
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• 1998

In order to estimate the life time of epoxy composites used for modeling material of transformer, the AC breakdown experiments of it were experimented and then the AC breakdown data were also simulated by Weibull distribution equation in this study. The life time of H100F65 specimen was the shortest and it of SH100F65 specimen was the longest, and as the AC voltage was applied to specimen for 50[min], the breakdown probability of each specimen was 31.2[%], 17.00[%], 84.36[%] and 12.35[%], respectively.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2000년도 KIASC Conference 2000 / 2000년도 학술대회 논문집
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• pp.69-72
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• 2000

AC losses in multifilamentary HTS tapes can be classified to hysteresis loss, coupling loss, and eddy current loss from the viewpoint of their generation mechanism. From the viewpoint of the major magnetic field component generating them, they can be classified to magnetization loss, transport loss, and total loss. Dividing superconductor to fine filaments, twisting filaments bundle and increasing transverse resistivity are effectively reduce magnetization loss and total loss when the external magnetic field is relatively large. Recently, twisted multifilamentary Bi 2223 tapes with pure silver matrix were fabricated and the reduction of magnetization loss was proved experimentally in the parallel magnetic field to the tape wide face. However, when the perpendicular magnetic field is applied, increasing transverse resistivity is required essentially to reduce the AC losses. The transverse resistivity was increased successfully by the introduction of resistive barrier between filaments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1230-1232
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• 2000

To reduce harmonics in the AC line and achieve a unit power factor, A 4 paralled single phase PWM AC/DC converter has been proposed. In this paper, the coupling components are derived analytically from PWM converter input transformer model and control scheme to solve this problem is proposed. Unit power factor was obtained and the AC-side current harmonics were reduced. Simulation results show the usefulness of the proposed method and applicability to PWM converter in auxiliary block of high speed train.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2330-2334
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• 2014

본 논문에서는 무선 신호전송을 위한 비접촉 방식의 AC커플링(Coupling)기반 평면 나선형 인덕터의 주파수 특성을 분석하였다. 기판의 유전상수의 변화는 소자의 인덕턴스에 직접적인 영향을 주지 않고 소자의 전기용량에 영향을 주어 공진주파수를 변화시키는 것을 알 수 있다. 기판의 두께가 증가할수록 인덕턴스는 증가하지만 공진주파수는 감소하였으며, 이것은 기판 두께의 감소로 인해 내부 전기용량이 증가하였기 때문이다. 인덕터의 도체 선 폭이 증가하여도 전체 인덕터 크기와 턴 수 및 선 간격이 일정함으로 내부 사각 코일의 도선 면적이 작아지게 되어 각각의 자기 인덕턴스가 감소하게 되고 공진주파수는 증가되게 된다. 또한, 도체의 선 간격이 증가하면 내부 사각 코일의 도선 면적이 작아지게 된다.

• 전자공학회논문지A
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• 제31A권6호
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• pp.88-97
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• 1994

We describe the design, fabrication, and performance of the optical fiber-photodiode 1$\times$12 arry module using mesa-type InS10.53T GaS10.47TAS/INP 1$\times$12 PIN photodiode array. We fabricated the PIN PD array for high-speed optical fiber parallel data link optimizing quantum efficiency, operating speed sensitivity from the PIN-FET structure, and electrical AC crosstalk. For each element of the array, the diameter of the photodetective area is 80 $\mu$m, the diameter of the p-metal pad is 90 $\mu$m, and the photodiode seperation is 250 $\mu$m to use Si v-groove. Ground conductor line is placed around diodes and p-metal pads are formed in zigzag to reduce Ac capacitance coupling between array elements. The dark current (IS1dT) is I nA and the capacitance(CS1pDT) is 0.9 pF at -5 V. No signifcant variations of IS1dT and CPD from element to element in the array were observed. We calulated the coupling efficiency for 10/125 SMF and 50/125 GI MMF, and measured the responsivity of the PD array at the wavelength is 1.55 $\mu$ m. Responsivities are 0.93 A/W for SMF and 0.96 A/W for MMF. The optical fiber-PD array module is useful in numerous high speed digital and analog photonic system applications.