• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.12
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• pp.802-807
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• 2015

This paper describes the development of a piezoelectric level switch, which aims to effectively monitor the level status in high ambient temperatures. In order to adjust the impedance near the resonant frequency and temperature characteristics, the effect of the case and backing layer materials on its performance was analyzed using the finite element method (FEM). The suggested prototype new level switch has three heat-sink plates attached to SUS bar of 230 mm long, and case of PEEK which contains PZT sensing part. To illustrate the validity of this level switch, 10 samples are prepared and investigated the sensing performance through the high and low temperature ambient.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.5
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• pp.57-64
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• 2015

This paper proposes a new switching algorithm for an controllable clamp snubber to improve the efficiency of a fly-back converter system. This system uses an controllable clamp method for the snubber circuit for the efficiency and reliability of the system. However, the active clamp snubber circuit has the disadvantage that system efficiency is decreased by switch operating time because of heat loss in resonance between the snubber capacitor and leakage inductance. To address this, this paper proposes a new switching algorithm. The proposed algorithm is a technique to reduce power consumption by reducing the resonance of the snubber switch operation time. Also, the snubber switch is operated at zero voltage switching by turning on the snubber switch before main switch turn-off. Experimental results are presented to show the validity of the proposed controllable clamp control algorithm.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.7
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• pp.43-48
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• 2008

The characteristics of heat transfer of the bimetal disc for over-current protection device is specified. Bimetal consists of two metals which have a different thermal expansion coefficient. To analyze the thermal characteristics, temperature distribution when bimetal acts as a switch is calculated. As usual, heat source is applied to the bimetal and electric current is heat source in the over-current protection switch. In this paper, thermal distribution are obtained by solving a coupled electro-thermal field with 3D finite element method.

• Proceedings of the KIEE Conference
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• 2000.07e
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• pp.157-161
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• 2000

The electronic ballasts for low pressure discharge lamps are produced and commercialized. However, the electronic ballasts for high pressure lamps are now in progress because of poor reliability and high cost. The major case of troubles with electronic ballasts are thermal destruction of semiconductor output switches due to non ideal i-v characteristics of switch. The loss converts to heat and rises the temperature of switch and it increases proportionally to switching frequency and value of current and voltage. This study shows the variable frequency ballasts which can suppress the heating of switches efficiently. It is used for the limitation the switch current and the rising temperature of switch by impedance variation of lamp inductor. As a result, initial warm-up time of the proposed ballasts was faster than that of magnetic ballasts about 90 msec. Power factor of tested ballasts follow as ; input and output average of magnetic ballasts are 93 [%] and 86 [%], respectively, And proposed ballasts are 97 [%] and 99 [%], respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.10
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• pp.51-56
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• 2004

We propose and fabricate an 1${\times}$2 asymmetric optical switch by TOE using SOI wafer based on silicon which has very large TOE figure and it is a good material for optical devices. SOI wafer consists of 3 layers; upper Si layer for device(waveguide;core, n=3.5), buried oxide layer for insulator(clad, n=1.5) and Si substrate layer. We designed 1${\times}$2 asymmetric y-branched single mode optical waveguide switch by BPM simulation and metal heater by heat transfer simulation. Fabricated switch shows about 3.5 watts of power consumption and over 20dB of crosstalk between output channels.

• Laser Solutions
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• v.3 no.3
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• pp.21-29
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• 2000

For the direct metal shape processing the powder feed device which is different from the widely used in rapid prototyping. is developed, The three dimensional object is shaped with the melting metal powder. The developed research has applied to rapid prototyping in ultraprecision for MEMS and medical science fields required of rapid manufacture of complex shape. The goal of this study make 3D model which has precision accuracy. Powder spreading apparatus has been more improved because that the control of powder spread is very important in layer manufacturing. It consists of the vibration motor, nozzle and tube which supplies various metal powder. This apparatus could control the spreading velocity that could control powder spreading thickness. Laser on/off switch was adapted because laser scanning velocity must be preserved constantly to prevent heat transformation of laser overheating. The error between sintered thickness md experimental one occurred by shrinkage in sintering melting process. The problem of heat transformation was solved by On/Off switching system.

• Fire Science and Engineering
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• v.24 no.5
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• pp.136-141
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• 2010

The purpose of this study is to examine the structure and heat generation mechanism of low voltage switches used to turn on or off the power supply to an indoor lighting system and investigate how the fixtures and movable contacts of the switches are damaged depending on the types of energy sources in order to secure the judgment base for expected PL disputes. Based on the Korean Standard (KS) testing method for incombustibility, this study applied a general flame to the switch. In addition, current was supplied to the switch using the PCITS (Primary Current Injection Test System). The ambient temperature and humidity were maintained at $22{\pm}2^{\circ}C$ and 40~60% respectively while performing the test. It is thought that the switch generated heat due to a defective connection of the wire and clip, insulation deterioration and defective contact of the movable contact, etc. The surface of the switch damaged by the general flame was uniformly carbonized. When the flame source was removed, the fire on the switch was extinguished naturally. From the result obtained by disassembling the switch carbonized by the general flame, it could be seen that fixtures and movable contacts remained in comparatively good shape but the enclosure, clip support, movable contact, indicating lamp, etc. showed carbonization and discoloration. In the case of the switch damaged by overcurrent, the clip connecting the wires, clip support, etc. showed almost no trace of damage, but the fixtures, movable contact, indicating lamp, etc. were severely carbonized. That is, the sections with high contact resistance were intensively damaged and showed a damage pattern indicating that carbonization progressed from the inside to the outside. Therefore, it is possible to judge the initial energy source by analyzing the characteristics of the carbonization pattern and the metal fixtures of damaged switches.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1255-1260
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• 2003

In order to reduce driving power consumption, we propose and fabricate a new structure of asymmetric SOI 1${\times}$2 thermo-optic switch that has a back side silicon trenched structure. Compared to conventional SOI thermo optic switches without heat sink structure, it shows an improvement of switching power reduction from about 4 watt to 1.8 watt without sacrificing cross talk of about 20 ㏈ at the light wavelength of 1.55 $\mu\textrm{m}$. Here we also described the main design consideration and fabrication procedure for the proposed device.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1876-1879
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• 2003

Due to the conventional half-bridge switch-mode converters for dc motor drive have been usually using unbalanced circuit topologies which generate common-mode currents through parasitic capacitors distributed between the ground and the dc motor frame such as the heat-sink of switching devices or the frame of the dc motor. This paper describes methods that cancel common-mode current generated in half-bridge switch-mode converters by using circuit balancing technique. The circuit balancing is to make the noise pickup or occurring in both conductor lines, signal and return pathes, is equal in amplitude and opposite in phase so that it will be canceled out in the ground plane. The common-mode current cancellation in the proposed converter is confirmed by experimental results.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.714-716
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• 2001

This paper is about the characteristic analysis of a heater-trigger HTS switch. It is composed of a BSCCO tape wire and a heater as a thermal quench source. To minimize the heat flow to the liquid nitrigen, the epoxy was used around them. The heater-trigger switch operates in the process that the HTS tape is thermally quenched by the current flowing through the heater. Since the switch works in coolant, it needs to be designed by the accurate thermal characteristic analysis. Here, we focus on FEM for it.