Dae-Hee Park

Development and Characterization of Optimum Heat Sink for 30 W Chip on Board LED Down-Light

An optimum heat sink for a 30 W chip on board (COB) LED down-light is designed, fabricated, and characterized. By using the SolidWorks Flow simulator and thermal analysis software, the thermal characteristics of the optimum heat sink is analyzed. Four different types of heat sink are simulated and an optimum structure of the heat sink is found. The simulated temperature of the heat sink when operating the LED down-light is , which is only a difference of from the measured temperature. In order to reduce the temperature further, a copper spreader is introduced to the heat sink. The temperature of the heat sink with the copper spreader is lower than without the copper spreader.

Development of smart LED lighting system using multi-sensor module and bluetooth low energy technology

A smart LED lighting system is designed and implemented using a multi-sensor module and Bluetooth Low Energy (LE) technology. In order to monitor the environmental information such as ambient light intensity, temperature, and/or activity of human or other objects, a multi-sensor module including an ambient light sensor, temperature sensor, and motion sensor is combined to a microcontroller. By collecting environmental information, the LED lighting system can be controlled automatically. Through the Bluetooth LE technology, a user can monitor the environmental information on a smartphone and/or control the LED lighting system manually. Two features, multi-sensor module and Bluetooth LE, let the LED lighting system be more intelligent, energy efficient, and convenient lighting system.

Thermal Analysis and Equivalent Lifetime Prediction of Insulation Material for Nuclear Power Cable

The activation energy of a material is an important factor that significantly affects the lifetime and can be used to develop a degradation model. In this study, a thermal analysis was carried out to evaluate and collect quantitative data on the degradation of insulation materials like EPR and CSP used for nuclear power plant cables. The activation energy was determined from the relationship between log and 1/T based on the Flynn.Wall.Ozawa method, by a TGA test. The activation energy was also derived from the relationship between ln(t) and 1/T based on isothermal analysis, by an OIT test. The activation energy of EPR derived from thermal analysis was used to calculate the accelerated aging time corresponding to the number of years of use, employing the Arrhenius equation, and determine the elongation corresponding to the accelerated aging time.

Load current and Temperature measurement system for Measuring the Degradation of Power cable

Recently, there has been a surge in interest in equipment diagnosis and monitoring technology from the perspective of providing quality electricity in terms of reliability and safety. In order to meet the electrical demands of consumers, reliability of power supply needs to be maintained. For this purpose, a monitoring system for power cable is very important. Since real-time measuring equipment has many advantages, it is highly applicable. By measuring the load current and the surface temperature of power cables, we have monitored and identified the deterioration phenomena of power cables in operation. Since direct measurement of the cable conductor temperature is not easy, we have measured the surface temperature instead, and converted that temperature to obtain the conductor temperature of the cables. In addition, we have designed a system to detect the deterioration processes of the power cables in operation.

Load Current and Temperature Measurement for Measuring the Insulation Resistance of the 6.6 kV Cable

Department of Electronic Software Engineering, Hansei University, Kunpo 435-742, Korea(Received December 11, 2014; Revised December 19, 2014; Accepted December 23, 2014)Abstract: The cable degradation process is largely divided into three steps; Step 1 : Thermal degradation, Step 2 : Weibull degradation, Step 3 : Partial discharge. it is progress in step order. This article aims to explain the process of cable degradation using the method of insulation resistance and accordingly to compose and manufacture a system of measuring the life of electrical cable. Before measuring the insulation resistance, a system of measuring the temperature and current of cables was made, and the established system was installed for test on the site of a power plant to collect the measured data. The current sensor was used TFC30P80A-CL420, and temperature sensor was used the DK-1270 PT100 sensor as RTD sensor. When measured the temperature and the load current at the same position, was confirmed that in case of the load current value was high, also temperature value high. Therefore, the correlation between load currents and temperature was verified, and the analysis of diagnostic data was evaluated, which could be utilized in identifying the fault condition of cable systems.Keywords: Insulation resistance, Power cables, Load current, Surface temperature

A Study on Perpendicular Flame Retardant Characteristic Improvement of Halogen-free Flame Retardant Compounds by Nanoclay Addition

DYM Co., Ltd., Cheonan 331-290, Korea(Received December 3, 2014; Revised December 12, 2014; Accepted December 16, 2014)Abstract: The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.Keywords: Nanoclay, Flame retardant, Halogen free, Thermal resistance, Oxygen index

A Study on Improving the Efficiency of a Heat Dissipation Design for 30 W COB LED Light Source

In this paper, thermal analysis of heatsink for 30 W class Chip-on-Board (COB) LED light source is performed by using SolidWorks Flow Simulation package. In order to increase the convection heat transfer, number of fin and shape of the heatsink is optimized. Furthermore, a copper spread is applied between the COB LED light source and the heatsink to mitigate the heat concentration on the heatsink. With the copper spread, the junction temperature between the COB LED light source and the heatsink is , which is lower than the heatsink without the copper spread. Due to the improvement of the junction temperature, the light output is improved by 5.8% when the LED light source is stabilized. The temperature difference between the simulation and measured result of the heatsink with the copper spread is within , which verifies the validity of the thermal design method using a simulation package.

Thermal Properties of Semiconductive Composites for DC Power Cable

In this paper, semiconducting shield specimens for a DC cable os fabricated and characterized by measurement of volume resistance, tensile strength, and the coefficient of expansion to show the electrical and mechanical characteristics of the semiconducting shield. Due to the PTC phenomenon, the volume resistance at increases rapidly in comparison to the volume resistance at . Since the compounding ration of carbon black is low, the tensile strength and density become lower and the coefficient of expansion is increased. As the general specification of the tensile strength and density is and 150%, respectively, the fabricated specimen in this paper has excellent mechanical characteristic.

Electrical and Mechanical Properties of Semiconductive Composites for DC Power Cable

DYM Co. Ltd., Cheonan 330-290, Korea(Received December 6, 2012; Revised December 20, 2012; Accepted December 22, 2012)Abstract: In this paper, semiconducting shield specimens for a DC cable is fabricated and characterized by measurement of volume resistance, tensile strength, and the coefficient of expansion to show the electrical and mechanical characteristics of the semiconducting shield. Due to the PTC phenomenon, the volume resistance at 25℃ increases rapidly in comparison to the volume resistance at 90℃. Since the compounding ratio of carbon black is low, the tensile strength and density become lower and the coefficient of expansion is increased. As the general specification of the tensile strength and density is 0.8 kgfmm