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$CeO_2$을 첨가한 $Pb(Mg, Te, Mn, Nb)O_3-PZT$계 세라믹스의 물리적 성질과 압전트랜스의 출력특성
박순태,정수태,이종헌 한국세라믹학회 1993 한국세라믹학회지 Vol.30 No.9
Electrical and mechanical properties of Pb(Mg, Te, Mn, Nb)O3-PZT ceramics are investigated as a function of CeO2 addition (0 to 0.3wt%), and the output characteristics of piezoelectric transformer are also presented. The grain size decreased and the shapes of particles were more uniform with the addition of CeO2. The coercive electric field(9500V/cm), mechanical quality factor (2500) and bend strength (1065kg/$\textrm{cm}^2$) were improved by addition of CeO2 0.2wt%. After repetition of a number of stress cycles, the degradation of k33 was not found in this sample. The voltage step-up ratio (Vdc/Vrms) of piezoelectric ceramic transformer (half wavevoltage doubler, load resistor 100M.ohm) was about 950 in a linear region, its value was relatively higher than other materials.
측정한 산란계수에 의한 HEMT Modeling 변수의 결정에 관한 연구
박순태,손병문,Park, Soon-Tae,Son, Byung-Moon 대한전자공학회 2000 電子工學會論文誌 IE (Industry electronics) Vol.37 No.1
본 논문에서는 HEMT의 산란계수와 DC특성을 측정하여 모델링 변수들을 정확하게 추출하는 방법을 제안하였다, HEMT의 소신호 등가회로 모델링 변수들 중 extrinsic 직렬 저항은 측정한 DC특성을 이용하여 FUKUI 방법으로 구하였고, 다른 모델링 변수들은 HP 8510C Network Analyzer를 사용하여 여러 바이어스에서 측정한 S-parameter를 이용하여 변수 값을 결정하였다. 최적화 과정을 거쳐 얻은 등가 회로의 중요한 변수인 gm값은 실제 측정한 gm값과 0.078%오차만을 보인 반면, 제작자가 제공한 데이터를 이용하여 최적화하여 얻은 gm값은 실제 측정한 gm값과 175.38%나 오차를 보였다. 그러므로 반드시 정확하게 측정하여 얻은 초기 값을 가지고 정확한 변수를 측정할 수 있다는 것과 HEMT 모델링 변수들을 추출하는 과정을 자세하게 제시했다. An accurate technique to retrieve HEMT modeling parameters with measurements of S-parameters and DC characteristics of HEMT is proposed. The extrinsic series resistances among HEMT modeling parameters are determined by the FUKUI method using the measured DC characteristics. And other parameters are determined by the measured S-parameters by HP 8510C Network Analyzer with various values of DC bias. The transconductance retrieved from the measured S-parameters, however, shows only 0.078% error comparing with the measured gm values. Therefore, the S-parameters measured directly for an individual transistor should be used for an accurate determination of the model parameters. The procedure for the retrieval of the circuit modeling parameters redescribed in detail in this thesis.
박순태,모수원,이광배 한국무역통상학회 2021 무역통상학회지 Vol.21 No.2
A large number of empirical studies have attempted to examine an association between exchange-rate risk and international trade flows after the collapse of the Bretton Woods system in the early 1970s due to its importance in exchange-rate arrangement and trade policies. Unfortunately numerous empirical investigations not only have failed to offer conclusive evidence, but have neglected the behavior pattern of international trade flows themselves. In this paper, after setting a few preliminary elements, we first review the characterization of asymmetry and leverage effects in terms of conditional variances and news impact curve for Incheon port’s export. This paper employs the news impact curve measuring how new information is incorporated into export volatility estimates for Incheon port. We show that the news impact curve for the EGARCH model increases exponentially in both directions but with different parameters and that the EGARCH model differs from the standard GARCH model in two main respects: The EGARCH model allows good news and bad news to have a different impact on volatility, while the standard GARCH model does not, and the EGARCH model allows big news to have a greater impact on volatility than the standard GARCH model. We also show that the GJR news impact curve captures the asymmetry in the effect of news on volatility because it has a steeper slope in its negative side than on its positive side.
박순태,정수태,이종헌 한국전기전자재료학회 1995 電氣電子材料學會誌 Vol.8 No.1
The analysis of nonlinear equivalent circuit and the resonance characteristics of input current and output voltage were simulated, and their electrical properties are discussed in the transverse-type piezoelectric ceramic transformer. The nonlinear resonance characteristics of input current and output voltage showed by the thermal effect due to a higher driving current, the nonlinearity increased greatly as driving current increased. When load resistor was 100[M.ohm.], the nonlinear coefficient was -1.3. The nonlinear resonance curve of input current and output voltage for a variation of input voltage and load resistor agreed with the discussed theory. The output voltage increased nearly proportioned to input voltage when load resistors were below 50[M.ohm.], the voltage step-up ratio decreased when a load resistor was 100[M.ohm.] and their maximum value was 950.