• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.601-602
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• 2008

This paper presents pulse-frequency modulation(PFM) to improve the light-load efficiency. The proposed circuit is designed by using the device parameter of standard $0.13{\mu}m$ CMOS process. The performance of proposed circuit is evaluated by HSPICE simulation Measured efficiency in a light-load is measured 78-90 % for 0.1 to 100mA output current.

• Proceedings of the KIEE Conference
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• 2007.10a
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• pp.187-188
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• 2007

This paper describes a simple and high-performance LDO regulator designed using a $0.18{\mu}m$ CMOS process. It is designed to provide a regulated voltage for on-chip small loads instead of for off-chip heavy loads. Since the load capacitance is very small in this applications, the frequency compensation can be easily achieved without a buffer. The designed LDO drives a load current up to 15mA and dissipates only 12uA quiescent current. The line regulation is and the load regulation is for a 9mA load step. The PSRR at 10kHz is 54dB.

• ETRI Journal
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• v.27 no.4
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• pp.469-472
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• 2005

To enhance the scalability of high performance packet switches, a two-stage load-balanced switch has recently been introduced, in which each stage uses a deterministic sequence of configurations. The switch is simple to make scalable and has been proven to provide 100% throughput. However, the load-balanced switch may mis-sequence the packets. In this paper, we propose an algorithm called full frame stuff (FFS), which maintains packet order in the two-stage load-balanced switch and has excellent switching performance. This algorithm is distributed and each port can operate independently.

• Journal of Power Electronics
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• v.8 no.4
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• pp.354-362
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• 2008

This paper presents neural load torque compensation method which is composed of a deadbeat load torque observer and gains compensation by a parameter estimator. As a result, the response of the PMSM (permanent magnet synchronous motor) obtains better precision position control. To reduce the noise effect, the post-filter is implemented by a MA (moving average) process. The parameter compensator with an RLSM (recursive least square method) parameter estimator is adopted to increase the performance of the load torque observer and main controller. The parameter estimator is combined with a high performance neural load torque observer to resolve problems. The neural network is trained in online phases and it is composed by a feed forward recall and error back-propagation training. During normal operation, the input-output response is sampled and the weighting value is trained multi-times by the error back-propagation method at each sample period to accommodate the possible variations in the parameters or load torque. As a result, the proposed control system has a robust and precise system against load torque and parameter variation. Stability and usefulness are verified by computer simulation and experiment.

• Journal of the Semiconductor & Display Technology
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• v.20 no.3
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• pp.157-160
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• 2021

In this paper, a 20W class multi-output QR flyback converter for auxiliary power supply was designed to stabilize 4 output voltages, and the efficiency and load characteristics were compared and analyzed. It was checked if each output affects other output characteristics through experiment. As a result, the experimental circuit reached a high efficiency of 82.5% or more at a load power of over 20W, and the maximum power loss was 2.6W. Consequently, it was confirmed that all of 4 output voltages of the multi-output QR flyback converter constructed in this paper were stabilized within 0.5% in full-load range, and each output was independently controlled in an electrically isolated state.

• Journal of Electrical Engineering and Technology
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• v.13 no.4
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• pp.1623-1630
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• 2018

Normally, various auxiliary loads are installed along with the main load in industrial applications. Usually, load transformers are used to convey such types of auxiliary loads. The transformers become energized when the loads are turned-on, consequently, high amplitude of inrush current appears at the output of the uninterrupted power supply (UPS) system. To mitigate these high current amplitudes, this manuscript suggests a three-phase line-interactive UPS system to counter the inrush current during the turning-on of the auxiliary load transformer while powering the main load by using a current controlled inverter. Experimental results of a laboratory-sized prototype are provided in the support of the proposed UPS system for validation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.233-236
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• 2010

This paper describes the packet traffic management of the Ubiquitous Healthcare System. In this system, ECG signal and accelerometer signal is transmitted from a wearable health shirt (WHS) to the base station. However, with the increment of users in this system, traffic over-load issue occurs. The main aim of this paper is to reduce the traffic over-load issue between sensor nodes by only transmitting the required signals to the base station when irregular activities are observed. In order to achieve this, in-network processing is adapted where the process of observation is conducted inside the sensor node of WHS. Results shows that irregular activities such as fall can be detected on real-time inside the sensor node and thus resolves traffic over-load issue.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.11
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• pp.696-701
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• 2016

In this study, to increase output of road piezoelectric energy harvester, it was made into rack type in which many piezoelectric materials can be installed and load transfer device of the leverage type to transfer vehicle load was made. By paving it in the road, the output characteristics depending on vehicle load and speed were evaluated. Changing vehicle load, harvester output characteristics depending on speed changes were evaluated at the interval of 10 km/h from 10 km/h to 100 km/h. Also, by making a wireless switch and sending wireless signal with output of rack type harvester, whether to receive it was evaluated by distance. It was checked that all switches work up to front-to-back 100 m from harvester.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.8
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• pp.629-634
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• 2013

The rectified voltage supplied to LED lamp is used in load and then the surplus voltage can be produced in LED lighting. In this case, LED lighting is proposed that can recyclable the excess voltage to supply power to the controller.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.74-77
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• 2005

An electronic step-down transformer is proposed. Conventional iron cored transformer is heavy and bulky and it has substantial amount of no load loss. On the other hand, electronic transformer can provide negligible no load loss, small size, and light weight. It consists of rectifier and PWM inverter. The output voltage is controlled by duty ratio. To confirm the validity of the proposed transform, simulation and experimental results are presented.