• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.852-856
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• 2000

In this paper, we investigated the output power, step-up ratio and efficiency properties of piezoelectric transformer with dielectric and piezoelectric characteristics of manufactured ceramics. The piezoelectric transformers with $2.0$\times$10$\times$48[$mm^3$] size were fabricated and its electrical properties were measured. When output power of 6W was constantly maintained, T2 piezoelectric transformer showed the minimum temperature rise of $9(^{\circ}C)$ at $150(K\Omega)$ load resistance. However, T1 piezoelecric transformer showed the temperature rise of $7.2(^{\circ}C)$ at $200(K\Omega)$ load resistance. The 6[w] CCFL (Cold Cathode Fluorescent Lamp) was successfully driven by T1 and T2 piezoelectric transformer but, its temperature rise $\Delta$T[$^{\circ}C)$] was generated more than $20(^{\circ}C)$. It is concluded that we have to design the piezoelectric transformers so that its output impedance correspond to the load impeadance, including any stray capacitance.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.115-118
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• 2000

In case of developing new motor, many examinations was tested to decide a motor efficiency and reliability. To give reliability judgment, traction motor winding insulation was tested by electrical method after appling electrical, heat, mechanical, environmental stress. In this study, stator form-wound winding of traction motor in urban transit E.M.U was tested by accelerative thermal degradation test. Stator form-wound winding was tested on the accelerative degradation composed of heat, vibration, moisture, overvoltage and researched insulation resistance, dielectric loss, partial discharge for insulation degradation properties, evaluated withstand voltage. Degradation temperature was $230[^\circ{C}]$, $250[^\circ{C}]$, $270[^\circ{C}]$, for stator form-wound winding respectively. On the test results of accelerative thermal degradation, insulation properties were relied all temperature until 10 times and expected life was evaluated by the rule of reducing $10[^\circ{C}]$ life into halves. Expected life was 31.8 years. It is guaranteed insulation reliability because of exceeding 25 years life times as considering.

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.655-661
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• 2006

Dielectric and piezoelectric properties of PMN-PZT ceramics with a high mechanical quality factor$(Q_m)$ and a low temperature sintering temperature were investigated as a function of PZN substitution in order to develop multilayer piezoelectric transformer for AC-DC converter. Multilayer piezoelectric transformers were subsequently manufactured using the PMN-PZN-PZT ceramic offering the optimal behavior and then the electrical performance were invetigated. At the sintering temperature of $940^{\circ}C$, density, electromechanical coupling factor$(k_p)$, mechanical qualify factor$(Q_m)$ and dielectric constant$(\varepsilon_r)$ of 8 mol% PZN substituted specimen were $7.73g/cm^3$, 0.524, 1573 and 1455, respectively. The PZN substitution caused a increase in the dielectric constant and the electromechnical coupling factor. The voltage step-up ratio of multilayer piezoelectric transformer showed the maximum value at near the resonant frequency of 76.55 kHz and increased according to the increase of load resistance. The multilayer piezoelectric transformer with the output impedance coincided with the load resistance showed the temperature increase of less than $20^{\circ}C$ at the output power of 10 W. Based on the results, the manufactured multilayer transformer using the low temperature sintered PMN-PZN-PZT ceramics can be stably driven for both step-up and down transformers.

• Journal of Korean Vacuum Science & Technology
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• 제5권1호
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• pp.11-18
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• 2001

Dielectric passivation effects on the EM(electromigration) have been a great interest with recent ULSI and multilevel structure tends in thin film interconnections of a microelectronic device. SiO$_2$, PSG(phosphosilicate glass), and Si$_3$N$_4$ passivation materials effects on the EM resistance were investigated by utilizing widely used Al-1%Si thin film interconnections. A standard photolithography process was applied for the fabrication of 0.7㎛ thick 3㎛ wide, and 200㎛ ~1600㎛ long Al-1%Si EM test patterns. SiO$_2$, PSG, and Si$_3$N$_4$ dielectric passivation with the thickness of 300 nm were singly deposited onto the Al-1%Si thin film interconnections by using an APCVD(atmospheric pressure chemical vapor deposition) and a PECVD(plasma enhanced chemical vapor deposition) in order to investigate the passivation materials effects on the EM characteristics. EM tests were performed at the direct current densities of 3.2 $\times$ 10$\^$6/∼4.5 $\times$ 10$\^$6/ A/cm$^2$ and at the temperatures of 180 $\^{C}$, 210$\^{C}$, 240$\^{C}$, and 270$\^{C}$ for measuring the activation energies(Q) and for accelerated test conditions. Activation energies were calculated from the measured MTF(mean-time-to-failure) values. The calculated activation energies for the electromigration were 0.44 eV, 0.45 eV, and 0.50 eV, and 0.66 eV for the case of nonpassivated-, Si$_3$N$_4$passivated-, PSG passivated-, and SiO$_2$ passivated Al-1%Si thin film interconnections, respectively. Thus SiO$_2$ passivation showed the best characteristics on the EM resistance followed by the order of PSG, Si$_3$N$_4$ and nonpassivation. It is believed that the passivation sequences as well as the passivation materials also influence on the EM characteristics in multilevel passivation structures.

• 한국전자파학회논문지
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• 제21권3호
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• pp.262-268
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• 2010

본 논문에서, 부성 저항 특성을 갖는 능동 커패시턴스 회로를 이용한 고출력 능동 가변 대역 통과 여파기는 동축형 유전체 공진기와 버랙터 다이오드를 사용하여 설계하였으며, 셀룰러 TX, RX 대역을 모두 가변할 수 있도록 설계하였다. 능동 커패시턴스 회로의 직렬 피드백 구조는 가변 대역 통과 여파기의 버랙터 다이오드로부터 생기는 손실을 보상함과 동시에 고출력 특성을 갖도록 하기 위해 $P_{1dB}$가 32 dBm인 GaAs HFET을 사용하였다. 버랙터 다이오드는 고선형 특성을 갖도록 하기 위해 back-to-back 구조를 사용하였다. 제작된 2단 능동 가변 대역 통과 여파기는 셀룰러 대역인 800 MHz에서 900 MHz를 가변하며, 각각 25 MHz 대역폭으로 TX 대역 836 MHz에서 0.48 dB 삽입 손실 특성을 나타냈으며, RX 대역 881.5 MHz에서 0.39 dB 삽입 손실 특성을 나타내었다. $P_{1dB}$특성은 TX 및 RX 대역에서 각각 19.5 dBm과 23 dBm을 얻었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.151-151
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• 2009

A enameled wire may have better corona-resistance when its coating material contains nano-sized inorganic particles. However, industrial applications are still limited because an aggregation between nanofillers may happen during coating processes. In this study we use a novel scheme of surface modification with silane on silica nanoparticles using sonochemical reaction where composition and surface density of silanes can be controlled in order to reduce particle-particle attractive interaction. Functionalized nanoparticles are evenly dispersed in the matrix confirmed by SEM and energy dispersive x-ray analysis. Dielectric strength and thermal resistance of the nanocomposite wires are improved while flexibility of the wire maintains.

• 한국전기전자재료학회논문지
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• 제19권1호
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• pp.40-45
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• 2006

Electrical insulation is one of the most important parts in a high voltage apparatus. Traditionally mineral oils and synthetic esters have been widely used as dielectric coolants for power transformers. Recently, researchers are interested in the environmentally friendly vegetable oil from the environmental viewpoint. This paper reports on the synthesis and characterization of soybean based ester oils. Two different types of soybean based transformer oils, named as methyl ester and isopropyl ester were synthesized. The synthesis of these esters was achieved by transesterification reactions between soybean oil and alcohol in the presence of catalyst. The GC and NMR spectroscopic analysis of the esters have been performed. It was observed that isopropyl ester has better thermal resistance than methyl ester by TGA. Also, two esters have a good breakdown voltage and electrical resistance.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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• pp.107-108
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• 2000

We propose the method which is possible to fabricate the electrodes with the fine pattern and low resistance by photolithography and electroplating. The widths of pattern fabricated were 30, 50, 70 and 100um and the thickness could be up to $10{\mu}m$. The resistivity of the copper electrode electroplated was below $2.0{\mu}{\Omega}$ cm which is about half of photosensitive silver electrode. Dielectric layer was coated on the electrodes by screen printing and the pores harmful to the discharge were not formed after heat treatment. In the viewpoint of resistance and patterning, this method has much higher potential for large area display than other methods like screen printing, photosensitive conductive paste method and sputtering.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.225-229
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• 1996

In this study, in order to develop outdoor insulating materials, SIN(simultaneous interpenetrating polymer network) was introduced to Epoxy resin and the environment resistance was investigated. The single network structure specimen(E series) formed of Epoxy resin alone and simultaneous interpenetrating polymer network specimen (EM series) in which epoxy resin was taken as the first network and methyl methacrylate resin as the second network were manufactured. Ten kinds of specimens were manufacture by filler (SiO$_2$) content. SEM were utilized in order to confirm their network structure changes, and AC voltage dielectric strength was measured. Also, UV-test and tracking test were carried out investigate the environment resistance characteristic. Therefore the variations of network structure were happened as a result of SEM test, and it was confirmed that simultaneous interpenetrating polymer network specimens were more excellent than single network structure specimens.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.491-491
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• 2011

Transparent and flexible electronic devices that are light-weight, unbreakable, low power consumption, optically transparent, and mechanical flexible possibly have great potential in new applications of digital gadgets. Potential applications include transparent displays, heads-up display, sensor, and artificial skin. Recent reports on transparent and flexible field-effect transistors (tf-FETs) have focused on improving mechanical properties, optical transmittance, and performances. Most of tf-FET devices were fabricated with transparent oxide semiconductors which mechanical flexibility is limited. And, there have been no reports of transparent and flexible all-organic tf-FETs fabricated with organic semiconductor channel, gate dielectric, gate electrode, source/drain electrode, and encapsulation for sensor applications. We present the first demonstration of transparent, flexible all-organic sensor based on multifunctional organic FETs with organic semiconductor channel, gate dielectric, and electrodes having a capability of sensing infrared (IR) radiation and mechanical strain. The key component of our device design is to integrate the poly(vinylidene fluoride-triflouroethylene) (P(VDF-TrFE) co-polymer directly into transparent and flexible OFETs as a multi-functional dielectric layer, which has both piezoelectric and pyroelectric properties. The P(VDF-TrFE) co-polumer gate dielectric has a high sensitivity to the wavelength regime over 800 nm. In particular, wavelength variations of P(VDF-TrFE) molecules coincide with wavelength range of IR radiation from human body (7000 nm ~14000 nm) so that the devices are highly sensitive with IR radiation of human body. Devices were examined by measuring IR light response at different powers. After that, we continued to measure IR response under various bending radius. AC (alternating current) gate biasing method was used to separate the response of direct pyroelectric gate dielectric and other electrical parameters such as mobility, capacitance, and contact resistance. Experiment results demonstrate that the tf-OTFT with high sensitivity to IR radiation can be applied for IR sensors.