• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1395-1396
• /
• 2015

본 연구의 목적은 광용적맥파 해석에 중요하게 사용되는 최대 상승기울기(maximum dV/dt) 지점 검출 알고리즘 개발로, 미분 및 필터링을 통한 전처리 과정, 극점 검출과정, 역탐색 등의 후처리 과정으로 구성되는 알고리즘을 구현하였다. 제안된 알고리즘의 성능을 평가하기 위하여 총 74,225개의 맥박파형을 사용한 검증을 수행하였으며, 동시에 측정된 심전도 QRS지점을 기준으로 최대 dV/dt 측정 위치 정확성을 판정하였다. 시뮬레이션 결과, 적응형 임계치 극점 검출 방법과 함께 사용하였을 때, 제안된 알고리즘은 기존 광용적맥파 상단, 하단극점 검출 알고리즘과 유사한 성능인 98.57%, 99.98%의 민감도와 특이도, 0.02%의 오검출율을 가지는 것으로 나타났다.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.5 no.1
• /
• pp.31-42
• /
• 1985

The most important and difficult part in the problem of unsteady seepage is, how to analyze a position and variation of free water level. Therefore, this paper found the relation between the rising water level and infiltration in the embankment by analyzing established equations and extrapolated the empirical equations from experimental data (For the seepage velocity; $V_S=Ki=k\frac{H-d_1}{d}$, For the rising velocity level; $V_R=\frac{dH}{dt}$) With the aid of these data, the necessary equations were compared with the experimental analyses.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.53 no.9
• /
• pp.538-544
• /
• 2004

This paper presents the interruption capability of serial-hybrid type GCB (gas circuit breaker) compared with that of puffer type. First a puffer type model interrupter which has the stroke length of 80 mm has been designed and manufactured. And also, a serial-hybrid type interrupter which has the same design parameters as the puffer type interrupter except the serially arranged thermal-expansion chamber and puffer cylinder has been fabricated. Using a simplified synthetic test facility, the critical interruption capabilities of the two GCBs have been estimated. The critical di/dt, the critical dV/dt of ITRV (initial transient recovery voltage) and the minimum arcing time of the puffer type model GCB were 10.7 A/${\mu}\textrm{s}$, 5.5 kV/${\mu}\textrm{s}$, and 15.0 ms respectively. In the case of serial-hybrid type model GCB, each of the values was 16.6A/${\mu}\textrm{s}$, 11.5 kV/${\mu}\textrm{s}$ and 13.0 ms. As a conclusion of this work, it has been quantitatively confirmed that the hybrid type interrupter can obtain the sufficient interruption capability at the operating force which is so low that puffer type interrupter has not the interruption capability.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.3C no.3
• /
• pp.73-76
• /
• 2003

In modern EHV (Extra High Voltage) class GCBs (Gas Circuit Breakers), the interruption capability for SLF (Short Line Fault) is one of the most important aspects of performance required for GCBs. Up to now, the SLF interruption capability of EHV class GCBs was partially assisted by the adoption of capacitors able to decrease the dV/dt of the TRV (Transient Recovery Voltage), particularly the TRV on the line side. This paper describes the technique to increase the SLF interruption capability of EHV class GCBs as well as the procedure to develop capacitorless l70kV 50kA GCB.

• Journal of the Korean Chemical Society
• /
• v.18 no.4
• /
• pp.259-266
• /
• 1974

Isotopic experiments using $H_2O^{18}$ on the oxidation of V(III) in acid perchlorate by molecular oxygen were performed in the range pH 1.0 to 3.0. At pH < 2, where a rate equation of the form TEX>$ -\frac{d[V(III)]}{dt}=k_1\frac{[O_2][V(III)]}{[H^+]}$ is adequate, the tracer study clearly indicated that all the product vanadyl ion's ($VO^{2+}$) oxygen originated from the molecular oxygen. At pH > ~2, where a different rate expression of the form $-\frac{d[V(III)]}{dt}=K_2\frac{[O_2][V(III)]^2}{[Ht]^2}$is required, the isotopic experiment showed that half the vanadyl oxygen originated from the molecular oxygen. Considering the results of the isotopic study, a mechanism for the V(Ⅲ)-O2 reaction at pH < ~2, may be suggested as follows: The tracer results at pH > ~2 imply that the rate determining step may be $$ V_2(OH)_2^{4+} + O_2 \rightarrow 2VO^{2+} + H_2O_2$$ followed by $$V_2(OH)_2^{4+} + H_2O_2 \rightarrow 2VO^{2+} + 2H_2O$$ after establishing the equilibria V^{3+} + H_2O \leftrightarrow VOH^{2+} + H^+, and 2VOH^{2+}\leftrightarrow V_2(OH)_2^{4+}$$

• Journal of IKEEE
• /
• v.18 no.4
• /
• pp.586-592
• /
• 2014

In this paper, high efficiency power management IC(PMIC) with DT-CMOS(Dynamic threshold voltage Complementary MOSFET) switching device is presented. PMIC is controlled PWM control method in order to have high power efficiency at high current level. The DT-CMOS switch with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuit consist of a saw-tooth generator, a band-gap reference(BGR) circuit, an error amplifier, comparator circuit, compensation circuit, and control block. The saw-tooth generator is made to have 1.2MHz oscillation frequency and full range of output swing from supply voltage(3.3V) to ground. The comparator is designed with two stage OP amplifier. And the error amplifier has 70dB DC gain and $64^{\circ}$ phase margin. DC-DC converter, based on current mode PWM control circuits and low on-resistance switching device, achieved the high efficiency nearly 96% at 100mA output current. And Buck converter is designed along LDO in standby mode which fewer than 1mA for high efficiency. Also, this paper proposes two protection circuit in order to ensure the reliability.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.300-303
• /
• 2003

The design rule for 8.5kV LTT was discussed here. An inherent integrated breakover diode (BOD) for self -protection function and multi-amplified gate (AG) for improved di/dt capability of LTT was introduced in principle. The trade-off between light triggering input source and high dV/dt limitation has been treated via narrow grooved P-base for gate design. Key process technology for LTT was given, too.

• Proceedings of the KIEE Conference
• /
• 2005.11a
• /
• pp.96-99
• /
• 2005

In this study, we build system and techniques of evaluating the interruption performance of the GCB with experimental method. We constructed a simplified synthetic test circuit of which ability is up to 245kV, 50kA BTF test. And We composed a model test circuit breaker with puffer assisted self blasting type GCB. With this circuit breaker, we carried out the experiment of no load and SLF90. During the tests, we measured the several factors such as stroke, pressure, arc temperature, the voltage and current near the current zero and dI/dt, dV/dt. Arc conductivity before 200ns before current zero which is one of the indexes of the thermal recovery of a GCB was measured. With these kinds of measurement, we could estimate the performance of a GCB fundamentally. Futhermore these results were used to adjust the arc modeling with CFD(computational fluid dynamics) and we could increase the plausibility of the analytical method.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.8 no.4
• /
• pp.313-320
• /
• 2003

This paper deals with the optimal design of a elevator inverter system based on the customized IPM. The proposed method reduces dv/dt and di/dt, which resulted in the minimized conducted EMI noise without an additional circuitry. It only optimizes the value of gate resistor in the IGBT embedded in the IPM. In order to optimize the customized IPM to a elevator system, we simulated and measured the spike voltage and the motor surge voltage including the temperature variation due to the switching losses at the IPM case and heat-sink. As a result, thanks to the optimized value of the gate resister in the IPM, the conducted EMI noise is reduced approx. 5∼10 [dB$\mu$V] in a particular frequency domain.

• Proceedings of the KIEE Conference
• /
• 2000.07c
• /
• pp.1533-1535
• /
• 2000

The design and fabrication technologies of pulse power reversely switched-on dynistor have been developed 1200V/120kA pulse power reversely switched-on dynistor device have been designed by analytically and numerically using commercial modeling S/W The important characteristics of reversely switched-on dynistors are breakover voltage $V_{BO}$, commutative peak voltage before steady state $V_m$, on-state voltage in steady state $V_o$, turn-off time $t_q$, dV/dt capability.