• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.257-258
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• 2011

This paper describes a new method for the seamless operation mode transfer of a PCS with minimized voltage disturbance. The proposed method provides reduced STS turn off time after line fault and smooth mode change between current and voltage control of the PCS. The usefulness of the method is verified through simulations with the consideration of the time delay in detecting a line fault and SCR turn-off time.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.355-361
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• 2011

The power control of the existing heating element has been using the On-Off control, phase control, and PWM control. In case of controlling power PTC heating element developed recently with the existing method, the temperature is unable to be precisely controlled or the harmful electromagnetic wave to human body is generated. In this paper, We suggest the power control of PTC heating cable using variable AC Cycles. This regards the AC cycle of N as the unit of the power control. It determines On-Off for each cycle. It is the AC power control method in which it arranges the on-cycle in N cycles in the random and it supplies the current continuously. At this time. the minimal electric power amount becomes 1/N. The maximum current amount becomes 1 and sets up the number of on cycles according to the set value and can control the electric power with the step of N consistently. In the PTC heating system, we show that proposed power control method is superior in the EMI and temperature control property using MATLAB simulation, experiments and measurements.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1661-1668
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• 2016

A fixed off-time controlled high power factor ac-dc LED driver is proposed in this paper, which employs a novel zero-crossing-compensation (ZCC) circuit based on a fixed off-time controlled scheme. Due to the parasitic parameters of the system, the practical waveforms have a dead region. By detecting the zero-crossing boundary, the proposed ZCC circuit compensates the control signal VCOMP within the dead region, and is invalid above this region. With further optimization of the parameters KR and Kτ of the ZCC circuit, the dead zone can be eliminated and lower THD is achieved. Finally, the chip is implemented in HHNEC 0.5μm 5V/40V HVCMOS process, and a prototype circuit, delivering 7~12W of power to several 3-W LED loads, is tested under AC input voltage ranging from 85V to 265V. The test results indicate that the average total harmonic distortion (THD) of the entire system is approximately 10%, with a minimum of 5.5%, and that the power factor is above 0.955, with a maximum of 0.999.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.152-156
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• 2007

This paper proposes a method for real-time control of both capacitors and ULTC in a distribution system to reduce the total power loss and to improve the voltage profile over the course of a day. The multi-stage consists of the off-line stage to determine dispatch schedule based on a load forecast and the on-line stage generates the time and control sequences at each sampling time. It is then determined whether one of the control actions in the control sequence is performed at the present sampling time. The proposed method is presented for a typical radial distribution system with a single ULTC and capacitors.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.4
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• pp.292-298
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• 2002

We focus on the slicing off some sub-nets using the transitive matrix. Control flows in the Petri nets is done based on the token flows. One control f]ow explains the independent tokens status and if the token-in divides into several tokens after firing a transition then the control flow divides to several flows, as well. Accordingly, we define that the basic unit of concur-rency (short BUC) is a set of the executed control flows based on the behavioral properties in the net. The BUC is S-invariant which has one control flow. We show the usefulness of transitive matrix to slice off some subnets from the original net based on BUC-through on an example.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.4
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• pp.418-425
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• 1998

In this paper. determination method of turn-off angle in the SRM drives is proposed to maintain the high torque at a any turn-on angle, which is realized by using selHuning control method, During the sampling time. a number of P pulses from encoder are checked by using one-chip microprocessor. and compared with pre-checked a number of pulses A After calculating difference between two data, the turn-off angle moves forward or backward direction by the self-tuning m method, As repeating such process, the optimal turn-off angle is determined and the maximum torque is maintained T Though experiments, it is observed that motor speed is almost maintained if turn-off angle is adjusted automatically by s selHuning method when turn-ηn angle is changed.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.751-753
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• 1999

In this paper, a simple SR method of AC motor has introduced. The method achived by appling the Pulse-Width Modulation(PWM) method to control the ON and OFF time of motor. The method is simple, practicable and has no problem of shift and out of control which is existed in SR method of SCR.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.1
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• pp.14-23
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• 2015

Although research and technology developments have recently increased to save lighting energy within buildings, such research and technology development are judged to be unsuitable for energy savings since they are limited in the sense that the application of the technology is fragmented. This study proposes a user and location awareness technology applied to dimming lighting control system and verified the effectiveness of energy savings by building a test bed. The results were as follows : 1) This study suggested a user and location awareness technology applied to dimming lighting control system. 2) The system shows 96.6% and 82.8% energy saving rates, respectively, on the basis of one user, compared to an on/off lighting control and the user and location awareness technology applied to on/off lighting control system. 3) The energy consumption of the user and location awareness technology applied to on/off lighting control system and the user and location awareness technology applied to dimming lighting control system increased to 96.6%, 88.3%, and 59.6% and 82.8%, 85.0%, 51.5%, respectively, on the basis of one, two, and three users, compared to the on/off lighting control system. This study confirmed the energy saving performance of the user and location awareness technology applied to the dimming lighting control system through performance evaluation. In this regard, further study needs to be undertaken to evaluate the performance at night time.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.12-19
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• 2015

In network-centric warfare, the communication network has played a significant role in defeating an enemy. Especially, the urgent and important data should be preferentially delivered in time. Thus, we proposed a priority MAC protocol based on CSMA/CA with Binary Exponential Back-off for tactical wireless networks. This MAC protocol suggested a PCW(Prioritized Contention Window) with differentiated back-off time by priority and a RBR(Repetitive Back-off Reset) to reset the remaining back-off time. The results showed that this proposed MAC has higher performance than those of DCF(Distributed Coordination Function) in the transmission success rate and the number of control packet transmission by reducing the packet collision. Thus, it produced more effective power consumption. In comparison with DCF, this proposed protocol is more suitable in high-traffic network.

• Journal of Internet Computing and Services
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• v.8 no.1
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• pp.33-45
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• 2007

Using switches and sensors informing the current on or off state, this paper suggests a sleeping control and remote monitoring system that not only can recognize the sleeping situations but also can control for keeping an appropriate sleeping situation remotely, And we show an example that this system is applied to the healthcare sleeping mat, Our system comprises the following 3 parts: a part for detecting the sleeping situations, a part for extracting sensing data and sending/receiving the relating situated data, and a part controlling and monitoring the all of sleeping situations. In details, in order to develop our system, we used the touch and pressure-sensitive sensors with On/Off functions for a purpose of the first part, The second part consists of the self-developed embedded board with the socket based communication as well as extracting real-time sensing data. And the third part is implemented by service modules for providing controlling and monitoring functions previously described. Finally, these service modules are implemented by the TMO scheme, one of real-time object-oriented programming models and the communications among them is supported using the TMOSM of distributed real-time middleware.