• Journal of Institute of Control, Robotics and Systems
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• v.11 no.11
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• pp.936-942
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• 2005

Recently the exoskeletal power assistive equipment which is a kind of wearable robot has been widely developed to help the human body motion. For the elderly people and patients, however, some limits exist due to the weight and volume of the equipments. As a feasible solution, a tendon-driven exoskeletal power assistive device fur the lower body, and caster walker are proposed in this research. Since the caster walker carries the heavy items, the weight and volume of the wearable exoskeleton are minimized. The key control is used to generate the joint torque required to assist motions such as sitting, standing and walking. Experiments were performed for several motions and the EMG sensors were used to measure the magnitude of assistance. When the motion of sitting down and standing up was compared with and without wearing the proposed device, the $25\%$ assistance was acquired.

• Journal of Power Electronics
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• v.10 no.6
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• pp.643-646
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• 2010

An interactive web-based teaching tool for a power semiconductor course at the University of Central Florida is presented in this paper. A novel approach is introduced using Technology Aided Design Tools (TCAD) to generate time-lapsed 2D semiconductor device cross-section embedded in a webpage using $Adobe^{(R)}$ Flash (web design tool) platform to create interactive movies that demonstrate complex device physical phenomenon. Students can step through the interactive movies forward, backward, pausing, or looping. Each step represents a giving bias condition. Current-voltage plots are represented along with the semiconductor device and a visual point is placed on the IV curve to indicate the current bias conditions. The changes are then reflected in the 2D cross-section movie area and the IV plot. This tool was implemented in a classroom setting to augment the lectures or for discovery learning.

• Journal of the Korean Society of Visualization
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• v.21 no.3
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• pp.23-32
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• 2023

This study aims to explore the heat transfer and flow phenomena inside an instant water heater and the influence of the design parameters of the water heater on the heating performance was investigated by 3-D numerical simulations considering heat convection. The design parameters are the heating ceramic dimension, the power of the heating device, and the water flow rate. The results show that a reasonable space for the heating device is required to optimize the heating performance. It is desirable to design higher heating device as possible for a given electric power. There exists a critical water flow rate that best meets the heating performance. The change in electric power has no impact on the flow phenomena and heating performance.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1071-1072
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• 2012

• Journal of Power Electronics
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• v.10 no.1
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• pp.85-90
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• 2010

In this paper the effects of a Static Synchronous Series Compensator, which is constructed with a 48-pulse inverter, on the power demand from the grid are studied. Extensive simulation studies were carried out in the MATLAB simulation environment to observe the compensation achieved by the SSSC and its effects on the line voltage, line current, phase angle and real/reactive power. The designed device is simulated in a power system which is comprised of a three phase power source, a transmission line, line inductance and load. The system parameters such as line voltage, line current, reactive power Q and real power P transmissions are observed both when the SSSC is connected to and disconnected from the power system. The motivation for modeling a SSSC from a multi-pulse inverter is to enhance the voltage waveform of the device and this is observed in the total harmonic distortion (THD) analysis performed at the end of the paper. According to the results, the power flow and phase angle can be controlled successfully by the new device through voltage injection. Finally a THD analysis is performed to see the harmonics content. The effect on the quality of the line voltage and current is acceptable according to international standards.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.2
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• pp.91-99
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• 2015

The electric power consumed by the embedded devices has become a critical issue because the reduction of power consumption is an important factor to prolong the battery-operated devices' lifetime. Many researches and techniques to reduce the power consumption have been proposed and developed but any power method cannot guarantee optimal power consumption of an embedded device - it would be faced with numerous situation - in all ways. Specifically, power researches for embedded devices deployed in the industry field have hardly been done. In this paper, low power service is proposed to minimize power reduction with the several usage status of embedded devices in the industry field. The usage status is basically classified according to the distance between the device and the user which is obtained by the ultrasonic and PIR sensor. The performance evaluation shows that the proposed scheme can reduce the power consumption by up to 45.3% compared to the device with no power reduction scheme. It also shows that the power consumption of the proposed scheme is 5.2% ~ 16.8% lower than that of the timeout scheme.

• 전기의세계
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• v.34 no.3
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• pp.141-144
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• 1985

다이리스터는 power semiconduct or device중에서 가장 광범위 또한 대용량의 전류와 전압을 취급할 수 있는 소자로써 널리이용되고 있다. 또한 silicon wafer의 크기가 증가하고 있기때문에 전류의 증가가 기대가 되고 있다. 그러나 MOSFEF의 power device의 응용이 증가되고 있으나 대용량의 전류와 전압의 조절분야에서는 다이리스터의 역할을 두드러질 것이다.

• Progress in Superconductivity and Cryogenics
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• v.19 no.4
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• pp.18-21
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• 2017

We report a method for improving heat exchange between cryo-cooled large-power-dissipation devices and liquid cryogen. Micro-machined monolithic heat sinks were fabricated on a high integration density superconducting Josephson device, and studied for their effect on cooling the device. The monolithic heat sink showed a significant enhancement of cooling capability, which markedly improved the device operation under large dc- and microwave power dissipation. The detailed mechanism of the enhancement still needs further modeling and experiments in order to optimize the design of the heat sink.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.3
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• pp.339-344
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• 2014

This paper presents a novel bipolar junction transistor (BJT) based electrostatic discharge (ESD) protection device. This protection device was designed for 20V power clamps and fabricated by a process with Bipolar-CMOS-DMOS (BCD) $0.18{\mu}m$. The current-voltage characteristics of this protection device was verified by the transmission line pulse (TLP) system and the DC BV characteristic was verified by using a semiconductor parameter analyzer. From the experimental results, the proposed device has a trigger voltage of 29.1V, holding voltage of 22.4V and low on-resistance of approximately $1.6{\Omega}$. In addition, the test of ESD robustness showed that the ESD successfully passed through human body model (HBM) 8kV. In this paper, the operational mechanism of this protection device was investigated by structural analysis of the proposed device. In addition, the proposed device were obtained as stack structures and verified.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.117-124
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• 2017

A Smart Grid is a system that can efficiently use energy by exchanging real-time information in both directions between a consumer and a power supplier using ICT technology on an existing power network. DR(Demand response) is an arrangement in which electricity users can sell the electricity they save to the electricity market when the price of electricity is high or the power system is crisis. In this study, we developed a power meter data transmission device and power IT system that measure the demand information in real-time using a smart meter and transmit it to a cloud server. The power meter data transmission device developed in this study uses alight sensor connected to a Raspberry Pi 3 to measure the number of blinking lamps on the KEPCO meter per unit of power, in order to provide reliable data without any measurement errors with respect to the KEPCO power data. The power measurement data transmission device uses the standard communication protocol, OpenADR 2.0b. The measured data is transmitted to the power IT system, which consists of the VEN, VTN, and calculation program, via the LTE WiFi communication network and stored in its MySQL DB. The developed power measurement data transmission device issues a power supply instruction and performs a peak reduction DR when a power system crisis occurs. The developed power meter data transmission device has the advantage of allowing the user to adjust it every 1 minute, where as the existing smart metering time is fixed at once every 15 minutes.