• Journal of the Korean Chemical Society
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• v.32 no.3
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• pp.276-284
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• 1988

The crystallization behaviours of poly(ethylene terephthalate) modified by 1, 3-propane diol, 1, 5-pentane diol, 1, 6-hexane diol, or poly(ethylene glycol) of molecular weight 300 as a third component were studied by isothermal and nonisothermal crystallization. When the content of the third diol was about 4 mol %, the isothermal crystallization rate at the same supercooling below the melting temperature and the nonisothermal crystallization rate at the same overheating above the glass transition temperature were increased more by the shorter flexible diol unit. On the contrary the nonisothermal crystallization rate at the same supercooling below the melting temperature was increased more by the longer flexible diol unit.

• Journal of the Semiconductor & Display Technology
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• v.13 no.4
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• pp.65-70
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• 2014

This paper is to improve the problem of the LED dimming control system using the conventional PWM and DAC method. The conventional PWM method controls the average current to switch dimming signal. This method generates the flicker when controlling at a low current. In order to solve the problem, this system prevents the flicker with the DAC method. The LED is lit at micro-current flowing in the LED. And offset voltage is generated in the output of the DAC when the DAC output is very low voltage as 0V. This was resolved by the voltage drop of the output voltage to construct a negative offset circuit. In addition, the LED current can't flow as set values because of overheating of FET. In order to solve the problem, the 16 bits ADC in the microprocessor is a more accurate current control receives the LED current in comparison with the set value. Therefore, the LED dimming control system proposed in this paper showed the accurate and reliable more than conventional systems.

• Journal of electromagnetic engineering and science
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• v.15 no.1
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• pp.20-25
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• 2015

A circularly rotated array for a dual polarized applicator in a superficial hyperthermia system is proposed. The applicator has a wider effective treatment area due to the $180^{\circ}$ phase shift. The dual polarized circularly rotated array (DPCRA) suppresses overheating at the center of the array and helps evenly distribute the heat. This array provides a more effective treatment area than a lattice array when a $2{\times}2$ dual polarized array is fitted to the treatment area. The treatment area is 71.5% of the aperture, whereas the effective treatment areas of the $2{\times}2$ dual polarized lattice array (DPLA) and the single polarized array (SPA) are 57.2% and 38.6% of the same aperture, respectively. The measurement matches the simulation results without blood circulation effects. In a $2{\times}2$ array applicator, the proposed DPCRA has more heat uniformity than the DLA and the SPA.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.200-203
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• 2005

Most of electrical fires are caused by short circuits, overheating of wires, deterioration and incomplete connection of wiring devices. The last two cases are predictable before the occurrence of fire because of its slow progress. In this paper, we have simulated the discharge signals caused by the deterioration and incomplete connection of wiring devices using an aged concent to provide information on the characteristics of discharge signals. From the experimental data, we could characterize the frequency spectrums of the discharge signals depending on the cases. The higher frequency components of the signal are attenuated by the capacitance and inductance of power lines as the measuring point is getting away from the discharges. Main frequency components of the discharge signal are existent at 600 kHz - 1.5 MHz in incomplete connections and at 210 kHz - 8 Mhz in deteriorations of the concent.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.130-137
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• 2005

LCD needs a backlight that is a light source as a photodetector that has a light modulation function and CCFL is used usually. Inverter that composes using existent winding transformer operates multi lamps, however, this efficiency falls by losses of core or winding and volume or weight increases or there is danger of fire by overheating. In order to solve these problems, a multi lamp driving Inverter using PT is composed according to the design guideline in this paper. We conformed whether the multi lamp drive method using EEFL that a current burden is less in applicable to piezoelectric inverter, and used the method that connect two piezoelectric transformers by parallel to an inverter.

• Journal of the Korea Furniture Society
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• v.28 no.3
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• pp.224-232
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• 2017

Building energy saving have been put effort in a long time since buildings consume about 40.6% of total energy use, where heating, cooling and electrical lighting requirement results in energy consumption of building significantly. The window is an important part of building envelope, it usually brings a certain heat load from solar radiation while it allows light passing through, and properly leads to overheating in summer, hence the cooling load increase sand cause of thermal uncomfortable factor. The purpose of this study was to evaluate internal shade performance according to color and materials. There is growing interest in improving the sense of comfort among students who spend most of their time in the classroom. The study examined thermal environment and light environmental performance according to the color and materials of internal blinds to the school classroom. The results of this study were as follows; Among wooden blinds, aluminium blinds, and polyester blinds, the aluminium blinds were most excellent. In addition, among white blinds, light brown blinds, dark brown blinds, the light brown were most excellent.

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.53-59
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• 1996

To protect the damages or the disasters caused by overheating of industrial electric equipments or electric home appliances, a temperature sensitive thermal fuse is generally used in those equipments. Thermal fuses cutoff the current flow when the temperature of the electric equipments are abnormally overheated and over the certain temperature. Therefore thermal fuse is one of the most important elements in the sense of safety. Thermal fuses are classified into two types according to thermally sensitive materials, a low temperature melting alloy and an organic chemical compound. Domestic products of thermal fuses are now only with an organic chemical compound. Domestic products tested by using cutoff test and aging test etc. are satisfied UL specification. It's shown that the accuracy and the precision of the domestic products are as good as those of the overseas products obtained UL mark. However, some of domestic products show the reclosing problem which is mainly related the safety. This problem should be solved to make the reliable thermal fuses. In this paper, our Interest is to find out the causes of reclosing. In the comparison between thermally sensitive materials occurred reclosing and those occurred no reclosing, the test effects show that the characteristics of emitting heat and absorbing heat are different.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.458-461
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• 2009

In 3-phase 4 wire system, appearance of the $3^{rd}$ harmonic current by increasing non-liner load is the one of causes overheating neutral wire of power line, and apparatus. So it is necessary to protect power-factor decreasing by the $3^{rd}$ harmonic, and electric power apparatus, and line safely, in this study, power system accidents caused by the $3^{rd}$ harmonic were investigated, then harmonic components analysis and unbalanced load analysis got accomplished. As result, we proposed the method to protect the power line and apparatus from over-current of neutral line by using the most economic 4-pole low voltage circuit breaker.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3030-3034
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• 2015

It is important to consider powertrain cooling performance, when engine is applied to new vehicle. If the performance is poor, engine will be damaged by overheating. But, the development timing of engine is faster than timing of vehicle, it is difficult to test the cooling performance of new engine and vehicle. In this study the powertain cooling performance was estimated with some test and calculation data. First, the heat rejection test was conducted. From this test, the heat rejection data at required rpm and load was acquired. Second, coolant flow test was conducted. From this test coolant flow rate to radiator was measured. Then engine torque and rpm was calculated from vehicle load and speed. Vehicle load and speed was calculated from test mode. Then by comparing these data, the powertrain cooling performance was estimated.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1595-1597
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• 2005

In this study, temperature sensors were adhered to transformer that is used in KHST(Korean High-Speed Train) to verify variation of temperature characteristics about transformer synthetically and efficiently. In the case that temperature of transformer exceeds reference temperature for running of KHST, overheating of transformer may cause a fatal accident of vehicle. Therefore, after on-line measurement system was constructed in vehicle, oil temperature and tank temperature were measured on real-time. Characteristics and main specifications of transformer in KHST were described in this paper. Also, measurement system for temperature measurement of transformer was explained in brief. Temperature data of transformer was acquired using measurement system, KHRI(Korea Railroad Research Institute) analyzed characteristic in contrast with comparing with temperature of transformer about month, running speed and running time.