• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.1
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• pp.17-23
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• 2005

The switching characteristics of MOS-Controlled Thyristor(MCT) is studied with variation of the channel length and impurity concentration in ON and OFF FET channel. The proposed MCT power device has the lateral structure and P-epitaxial layer in substrate. Two dimensional MEDICI simulator and PSPICE simulator are used to study the latch-up current and forward voltage-drop from the characteristics of I-V and the switching characteristics with variation of channel length and impurity concentration in P and N channel. The channel length and N impurity concentration of the proposed MCT power device show the strong affect on the transient characteristics of current and power. The N channel length affects only on the OFF characteristics of power and anode current, while the N doping concentration in P channel affects on the ON and OFF characteristics.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.668-673
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• 1998

The specimen of current study has the same type with the 3-span slabs of Burns et al used in the study by Mojtahedi/Gamble, which laid a ground for the revision of the ACI318-77 code to the ACI 318-83 code. But those specimens was failed prematurely before it reached the ultimate strength which the specimen had. The reason is that bonded reinforcements were cut off where there is no need for the flexural reinforcement. As results. the slabs failed ultimately where the reinforcements was cut off. Thus, the tendon stresses of failure may have been much smaller than the values which culd reach if the bonded reinforcements were extended beyond the theoretical cut off points. On the based on the fact mentioned above. the specimens which had the same conditions as the specimens of Burns et al were used in the current study, but in which the reinforcements were distributed in a sequence for the reinforcements not to be cut anywhere in the 3-span. As a results, it was known that the current ACI code, revised by the result of Mojtahedi/Gamble's study, overestimated the effect of span/depth ratio on the members with high span/depth ratio. Thus it was concluded that the effect of span/depth ratio on the ultimate stress of unbonded tendon regulated by the current ACI code must be reconsidered and reevaluated.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.315-318
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• 1999

We have proposed and fabricated the new bottom-gated polycrystalline silicon (poly-Si) thin film transistor (TFT) with a partial amorphous-Si region by employing the selective laser annealing. The channel layer of the proposed TFTs is composed of poly-Si region in the center and a-Si region in the edge. The TEM image shows that the local a-Si region is successfully fabricated by the effective cut out of the incident laser light in the upper a-Si layer. Our experimental results show that the ON/OFF current ratio is increased significantly by more than three orders in the new poly-Si TFT compared with conventional poly-Si TFT. The leakage current is decreased significantly due to the highly resistive a-Si re TFTs while the ON-series resistance of the local a-Si is reduced significantly due to the considerable inducement of electron carriers by the positive gate bias, so that the ON-current is not decreased much.

• Journal of the Korea Society of Computer and Information
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• v.23 no.9
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• pp.113-122
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• 2018

In this paper, IoT(Internet of things) technology, which is the core of the 4th industrial revolution, was applied to the study of reduction of consumption current. The IoT is a sensor that collects data, a sensor communication, a gateway that processes and stores the collected data. Data application of IoT technology is applied to smart home, smart city, healthcare, smart factory, etc. and it needs to be applied to various industrial fields. By sensing the location of the sensor device, the specific functions of the gateway and the platform are turned ON and OFF to reduce the consumption current of the equipment during the OFF period. When the sensor device accesses the gateway, the specific function of the gateway is turned ON and When the device is separated from the gateway, it senses the sensitivity of the wireless signal and automatically turns off the certain functions. As a resurt, it has reduced the consumption of current. In this paper, we propose a novel system for detecting the location of sensor devices by applying IoT technology. The system implementation is realized by software based, and defines the requirements for the implementation of the sensor device gateway. The gateway automatically detects the location, movement of the device and performs necessary functions. Finally verifies the automatic detection performance of the gateway according to the location of the device. It will contribute greatly to the development of the smart city and office.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.9
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• pp.723-726
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• 2012

A current intensity convertible CLD chip was fabricated using small and large FET cell configuration. Pinch-off current of 8.82 mA and 11.56 mA were obtained for small and large cell in the CLD chip, respectively. Constant current was fairly maintained until the breakdown voltage of 60 V. Measured knee voltage, $V_k$ were 3.8 V and 4.5 V for small and large cell, respectively. We configured current amplifying chip with parallel connection of each cells, by connecting 8 individual large cells in parallel network, 92.0 mA of current was obtained. The pinch-off constant current of CLD chip was varied very linearly with respect to the number of parallel connected cell.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.323-327
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• 1998

Under high power IGBTs Switching, a large overvoltage is induced across the IGBT module due to the stray inductance in the circuit. This paper proposes a new gate drive circuit for high power IGBTs which can actively suppress the overvoltage across the driven IGBT at turn-off while preserving the most simple and reliable power circuit. The turn-off driving scheme has adaptive feature to the amplitude of collector current, so that the overvoltage can be limited much effectively at the fault collector current. Experimental results under various normal and fault conditions prove the effectiveness of the proposed.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.6
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• pp.506-513
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• 2001

The torque of an SRM depends on the phase current and derivative of inductance. But an SRM is difficult to control the desired torques because of saturation in magnetic circuit An SRM is controlled by parameters of input voltage, and switch on , off angle The switch on off angles of an SRM regulate the magnitude and shape of current waveform and decide the magnitude and shape of torque This paper proposes an the optimization control scheme by adjusting both the switch on an switch off angle . The switch off angles are decided by reference of efficiency using simulation and experiments. The switch on angles are decided by load torque , And the dwell angles are controlled for torque control and speed control using GA-neural network which is used to simulated the reasonable switching angle.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.4
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• pp.562-567
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• 1996

A new lateral MOS controlled thyristor, named Shorted Anode LMCT(SA-LMCT), is proposed and analyzed by a two-dimensional device simulation. The device structure employs the implanted n+ layer which shorts the p+ anode together by a common metal electrode and provides a electron conduction path during turn-off period. The turn-off is achieved by not only diverting the hole current through the p+ cathode short but also providing the electron conduction path from the n-base into the n+ anode electrode. In addition, the modified shorted anode LMCT, which has an n+ short junction located inside the p+ anode junction, is also presented. It is shown that the modified SA-LMCT enjoys the advantage of no snap-back behavior in the forward characteristics with little sacrificing of the forward voltage drop. The simulation result shows that the turn-off times of SA-LMCT can be reduced by one-forth and the maximum controllable current density may be increased by 45 times at the expense of 0.34 V forward voltage drop as compared with conventional LMCT. (author). 11 refs., 6 figs., 1 tab.

• Journal of Power Electronics
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• v.19 no.1
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• pp.11-23
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• 2019

In this study, a novel zero voltage zero current transition (ZVZCT) bidirectional DC-DC converter is proposed by employing coupled inductors. This converter can turn the main switch on at ZVZCT and it can turn it off with zero voltage switching (ZVS) for both the boost and buck modes. These characteristics are obtained by using a simple auxiliary sub-circuit regardless of the power flow direction. In the boost mode, the auxiliary switch achieves zero current switching (ZCS) turn-on and ZVS turn off. Due to the coupling inductors, this converter can make further efficiency improvements because the resonant energy in the capacitor or inductor can be transferred to the load. The main diode operates with ZVT turn-on and ZCS turn-off in the boost mode. For the buck mode, there is a releasing circuit to conduct the currents generated by the magnetic flux leakage to the output. The auxiliary switch turns on with ZCS and it turns off with ZVT. The main diode also turns on with ZVT and turns off with ZCS. The design method and operation principles of the converter are discussed. A 500 W experimental prototype has been built and verified by experimental results.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.4
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• pp.307-312
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• 2006

This paper proposes the SRM drive system, which accurately estimates the phase currents from the DC-link current to drive SRM instead of detecting the three-phase currents. In addition, the detecting circuit of DC-link current is also proposed to increase the resolution and decrease the off-set influence. Comparing with the general drive system based on the phase current, it is verified through the experiments that the proposed SRM drive system based on the DC-link current has the good performance in steady-state response of the speed control. Using the DC-link current, all of the 3-phase currents can be easily estimated for driving the SRM.