Cellular CDMA 기지국에 Array 안테나 적용을 위한 수신 성능 시뮬레이션에 관한 연구 ( A study on the performance simulation of the cellular CDMA receiver working with a basestation array antenna )

박재준,배병재,김재화,장태규 대한전자공학회 1997 대한전자공학회 학술대회 Vol.1997 No.1

Effect of Ambient Temperature on the AC Electrical Treeing Phenomena in an Epoxy/Layered Silicate Nanocomposite

박재준 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.4

Effects of ambient temperature on the ac electrical treeing and breakdown behaviors in an epoxy/layered silicate (1 wt%) were carried out in needle-plate electrode geometry. A layered silicate was exfoliated in an epoxy base resin,, using our ac electric field apparatus. To measure the treeing initiation and propagation, and the breakdown rate, constant alternating current (ac) of 10 kV (60 Hz) was applied to the specimen in a needle-plate electrode arrangement, at 30℃, 90℃ or 130℃ of insulating oil bath. At 30℃, the treeing initiation time and the breakdown time in the epoxy/layered silicate (1 wt%) system were 1.4 times higher than those of the neat epoxy resin. At 90℃ (lower than Tg), electrical treeing was initiated in 55 min, and propagated until 1,390 min at the speed of 0.35×10-3 mm/min,which was 4.4 times higher than that at 30℃; however, there was almost no further treeing propagation after 1,390min. At 130℃ (higher than Tg), electrical treeing was initiated in 44 min, and propagated until 2,000 min at the speed of 0.96×10-3 mm/min. Typical branch type electrical treeing was obtained from the neat epoxy and epoxy/layered silicate at 30℃, while bush type treeing was observed out from the needle tip at 90℃ and 130℃.

Effects of Reactive Diluents on the Electrical Insulation Breakdown Strength and Mechanical Properties in an Epoxy System

박재준 한국전기전자재료학회 2013 Transactions on Electrical and Electronic Material Vol.14 No.4

In order to study the effect of reactive diluents on the electrical insulation breakdown strength and mechanical properties of, a polyglycol and an aliphatic epoxy were individually introduced to an epoxy system. Reactive diluents were used in order to decrease the viscosity of the epoxy system; polyglycol acted as a flexibilizer and 1,4-butanediol diglycidyl ether (BDGE) acted as an aliphatic epoxy, which then acted as a chain extender after curing reaction. The ac electrical breakdown strength was estimated in sphere-to-sphere electrodes and the electrical breakdown strength was estimated by Weibull statistical analysis. The scale parameters of the electrical breakdown strengths for the epoxy resin, epoxy-polyglycol, and epoxy-BDGE were 45.0, 46.2, and 45.1 kV/mm, respectively. The flexural and tensile strengths for epoxy-BDGE were lower than those of the epoxy resin and those for epoxy-polyglycol were lower than those of the epoxy resin.

Mechanical and Electrical Properties of Cycloaliphatic Epoxy/Silica Systems for Electrical Insulators for Outdoor Applications

박재준,김재설,윤찬영,신성식,이재영,정종훈,김영우,강근배 한국전기전자재료학회 2015 Transactions on Electrical and Electronic Material Vol.16 No.2

Mechanical and electrical properties of epoxy/silica microcomposites were investigated. The cycloaliphatic- typeepoxy resin was diglycidyl 1,2-cyclohexanedicarboxylate and the curing agent was of an anhydride type. To measurethe glass transition temperature (Tg), dynamic differential scanning calorimetry (DSC) analysis was carried out, andtensile and flexural tests were performed using a universal testing machine (UTM). Electrical breakdown strength, themost important property for electrical insulation materials, and insulation breakdown strength were also tested. Themicrocomposite with 60 wt% microsilica showed maximum values in mechanical and electrical properties.

Effect of Silica Particle Size on the Mechanical Properties in an Epoxy/Silica Composite for HV Insulation

박재준 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.5

In order to develop a high voltage insulation material, epoxy/micro-silica composites (EMC) and epoxy/micro-silica/nano-silica composites (EMNC) with three different particle sizes in μm and one particle size in nm were prepared and their tensile and flexural tests were carried out and the data was estimated by Weibull statistical analysis. The tensile strength of the neat epoxy was 82.8 MPa and those of the EMCs were larger than that of the neat epoxy, and they were much more advanced by the addition of 10 nm sized nano-silica to the EMCs. Flexural strength showed the same tendency of the tensile strength. As the micro-particle size decreased, tensile and flexural strength increased.

Long-term and Short-term AC Treeing Breakdown of Epoxy/Micro-Silica/Nano-Silicate Composite in Needle-Plate Electrodes

박재준 한국전기전자재료학회 2012 Transactions on Electrical and Electronic Material Vol.13 No.5

In order to characterize insulation properties of epoxy/micro-silica/nano-silicate composite (EMNC), long-term and short-term AC treeing tests were carried out undr non-uniform electric field generated between needle-plate electrodes. In a long-term test, a 10 kV (60 Hz) electrical field was applied to the specimen positioned between the electrodes with a distance of 2.7 mm in an insulating oil bath at 30℃, and a typical branch type electrical tree was observed in the neat epoxy resin and breakdown took place at 1,042 min after applying the 10 kVelectrical field. Meanwhile, the spherical tree with the tree length of 237 μm was seen in EMNC-65-0.3 at 52,380 min (36.4 day) and then the test was stopped because the tree propagation rate was too low. In the short-term test, an electrial field was applied to a 3.5 mm-thick specimen at an increasing voltage rate of 0.5 kV/s until breakdown in insulating oil bath at 30℃ and 130℃, and the data was estimated by Weibull statistical analysis. The electrical insulation breakdown strength for neat epoxy resin was 1,763 kV/mm at 30℃, while that for EMNC-65-0.3 was 2,604 kV/mm, which was a modified value of 47%. As was expected, the breakdown strength decreased at higher test temperatures.

Electrical Properties of Epoxy Composites with Micro-sized Fillers

박재준 한국전기전자재료학회 2018 Transactions on Electrical and Electronic Material Vol.19 No.6

Electric breakdown strength and dielectric properties of epoxy/micro-silica and epoxy/micro-alumina composites werestudied in order to develop an insulation material for high voltage application. Electrical insulation breakdown strength testwere carried out in sphere-plate electrodes and the data were statistically estimated by Weibull method. Dielectric propertieswas also tested for the specimen with 300 μm thick and 30 mm diameter. Electrical breakdown strength of epoxy/micro-silicawas higher than that of neat epoxy, and that for epoxy/micro-alumina was also higher than that of neat epoxy. And electricalbreakdown strength of epoxy/micro-silica composite was higher than that of epoxy/micro-alumina composite. As silica oralumina content increased, dielectric constant and tanδ increased.

Mechanical and Water Repellent Properties of Cycloaliphatic Epoxy/Microsilica/Nanosilica Composite

박재준 한국전기전자재료학회 2017 Transactions on Electrical and Electronic Material Vol.18 No.4

The effect of the content of microsilica and nanosilica continuously modified with hydroxy silane and epoxy-modified siliconein cycloaliphatic epoxy/microsilica/nanosilica composites (EMNCs) on the mechanical and water repellent properties wasevaluated. Surface-modified micro- and nanosilica was well-mixed with a cycloaliphatic epoxy resin in the presence ofpolyester-modified polydimethylsiloxane (PEM-PDMS) as a dispersing agent using an ultrasonicator. Tensile and flexuraltests were carried out using a universal testing machine (UTM). The water repellent property was evaluated by contact anglemeasurements of water on the composite surface. Tensile strength of the composite could be enhanced by 32.2% up to 91.4MPa, and the flexural strength was raised to 122.0 MPa, which is 38.8% higher than that of neat epoxy. The contact angle ofwater on the composite was as high as 104.1°.

누설 전류 모니터링에 의한 오손된 고분자 애자에서의 섬락 예지 방법

박재준,송영철 대한전기학회 2004 전기학회논문지C Vol.53 No.7(C)

In this paper, a flashover prediction method using the leakage current in the contaminated EPDM distribution polymer insulator is proposed. The leakage currents on the insulator were measured simultaneously with the different salt fog application such as 25g, 50g, and 75g per liter of deionized water. Then, the measured leakage currents were enveloped and transformed as the CDFS using the Hilbert transform and the level crossing rate, respectively. The obtained CDFS having different gradients(angles) were used as a important factor for the flashover prediction of the contaminated polymer insulator. Thus, the average angle change with an identical salt fog concentration was within a range of 20 degrees, and the average angle change among the different salt fog concentrations was 5 degrees. However, it is hard to be distinguished each other because the gradient differences among the CDFS were very small. So, the new weighting value was defined and used to solve this problem. Through simulation, it is verified that the proposed method has the capability of the flashover prediction.

Kaolin 오손물 누적량 모의실험 및 누설전류변화 특성

박재준,송일근,이재봉,천성남 대한전기학회 2005 전기학회논문지C Vol.54 No.11-C

This study performs a simulation for an accumulation mechanism of contaminants, which were produced in an industrial belt of inland, on the surface of insulators. From the simulation, silicon insulators presented higher accumulation than that of EPDM(Ethylene Propylene Diene Terpolymer : EPDM) insulators on the same distance in the case of the Virgin polymer insulator, and this result presented the same result in the insulator applied in actual fields. In the case of the accumulation test for the Virgin insulator and insulators used in actual fields, it is evident that the Virgin insulator presented more accumulation than that of the insulator used in actual fields. The results can be caused by the generation of LMW (Low Molecular Weight) on the external material of polymer insulators, and the level of the accumulation can be changed according to the degree of the continuous generation of LMW. In order to simulate a certain pollution of an industrial belt, which is located along the coastline, leakage currents were measured by applying the contaminant compulsively that was produced with salts and Kaolin according to the ratio of its weight on the surface of insulators. The more increase in the content of Kaolin pollution, the level of leakage currents on the surface of polymer insulator more increased. In addition, the approaching time to the maximum value of leakage currents presented a nearly constant level regardless of the content of Kaolin. The level of leakage currents significantly decreased according to the passage of time, and the level of leakage currents on the surface maintained a constant level at a specific time regardless of the content of Kaolin.