• Proceedings of the KIEE Conference
• /
• 1996.07c
• /
• pp.1541-1543
• /
• 1996

This paper describes the results of characteristics on the tracking resistance, hydrophobicity and dielectric properties of silicone rubbers used for outdoor insulation with ozone ageing. The tracking and ozone ageing tests for this purpose ware made in according to IEC 587 and ASTM D 1149, respectively. Additionally, we investigated the surface structure of the silicone rubbers with FT-IR and SEM. From the test results, it is proven that the higher the degree of ozon ageing, the worse tracking characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.516-517
• /
• 2008

The ethylene-propylene (EP) rubbers mixed with one to one ratio is used as an insulation material in the nuclear power plant. It was investigated the effect of the amount of reinforcing agent. moisture absorption and heat treatment on the Ethylene-Propylene(EP) rubbers. The level of degradation was measured by the amount of discharging and. charging currents. When $\gamma$ rays were radiated on the EP rubbers with more charging material, the amount of discharging and charging currents was depended on the amount of reinforcing agent It was verified that the discharging and charging currents irradiated by $\gamma$ rays were higher than those that was not irradiated.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 1998.04a
• /
• pp.34-34
• /
• 1998

일반 항공기 및 상용 복합 구조재의 경우에는 내부에 결함이 생길 경우 유지 및 보수가 용이하나 복합재 압력 용기의 경우에는 다양한 환경 변화를 겪게 되며 또한 유지 및 보수가 힘들다는 제약 조건이 있으므로 단열재로 사용되는 인슈레이션 고무와 FRP간의 접착, 가황 고무와 미가황 고무 사이의 접착 등 여러 가지 이종 재질들 간의 접착이 매우 중요한 변수가 될 뿐만 아니라 압력 용기의 전체적인 성능에도 상당한 영향을 미치게 된다. 이러한 시스템들은 제작 조건에 따라 결함이 발생하는 빈도가 차이가 나며 특히 가혹한 환경 조건하에서도 내구성을 보여야 하므로 본 실험에서는 다양한 환경 조건, 성형 조건을 가지는 FRP/고무, 고무/고무 접착 시스템의 계면 접착력을 측정한 후 이로부터 환경 노화에 저항성이 강한 최적의 접착제 및 접착 조건 등을 확립하고자 하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.13 no.6
• /
• pp.415-422
• /
• 2003

In an apartment buildings, the floor Impact sound from upstairs has been regarded as a main source of noise causing discontentment among occupants. To set the optimum design for sound insulation, it is necessary to suggest the useful tools or technique that predict the floor impact sound. The purpose of this study is to suggest the supplementary formula(equation) and constant k considering vibration transmissibility in order to predict more precisely heavy floor impact sound by Impedance Method that have been briskly studied in Japan from comparing the measured values with the predicted values. The analyzed results had showed that if the damping material was glass wool or rubber, k=5 was proper and if the damping material was polystyrene foam, k>5 was desirable.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2000.11a
• /
• pp.425-430
• /
• 2000

This paper describes the effect of the pad stiffness on the noise reduction of impact noise isolation pads of a floor. And also a new semi-experimental method for measuring the impact noise isolation capability of a pad is introduced. The impact noise isolation pads made of wire-mesh, urethane-chip and foam rubber are used for measuring the stiffness, the vibrational insulation performance and the impact noise isolation capability. The correlation between the stiffness and impact noise isolation capability of pads is theoretically reviewed, and confirmed from the experimental results. For measuring the impact noise isolation capability of only an isolation pad, a semi-experimental method proposed in this study is more effective than the reverberation room method.

• Elastomers and Composites
• /
• v.33 no.4
• /
• pp.238-245
• /
• 1998

In this paper, the electric property was investigated for insulation diagnosis of radiation of EPR electric power cables by partially irradiation with $^{60}Co-{\gamma}$ rays. As the rate of radiation increased from 100Mrad to 200Mrad, charging current and discharging current were increased from $1.03{\times}10^{-7}$(A) to $4.3{\times}10^{-9}$(A). In addition, we found charging current and discharging current of cables subjected to 50% and 16.7% irradiation changed the length of the part 1/2 to 1/6 as in comparison with cables degraded by 100% irradiation. For 22m and 66m of cables which had not been degraded yet, we realized the value of charging current and discharging current of 66m cables is three times higher than 22m cables. From these results, it is demonstrated that the possibility of utilizing charging current and discharging current as the diagnosis method of insulation degradation with irradiating EPR cables by $^{60}Co-{\gamma}$ rays.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05e
• /
• pp.40-43
• /
• 2003

전기방전에 대한 shed 재료의 열화내성과 우수한 발수성의 장기간 유지특성은 폴리머 애자의 장기성능에 있어서 가장 중요한 인자들이다. 애자 제조시 무결점 성형성 또한 중요한데 열화내성을 확보하기 위해 다량의 ATH의 첨가가 수반되기 때문에 적절한 process oil의 사용이 불가피하다. 사용하는 오일의 종류와 량에 따라 옥외절연물의 장기성능에 영향을 주는 표면발수성이나 방전내성은 크게 차이가 나는 것으로 밝혀지고 있다. 본 논문에서는 화학적 구조와 정도가 다른 몇 가지 실리콘 fluid들을 실리콘 고무에 처방하여 기본물성과 초고압 옥외절연물의 shed 재료로서 장기성능에 영향을 주는 방전열화내성과 표면발수성의 회복특성을 평가하였다. 실리콘 고무의 무결점 사출성형에 가소도가 중요한데 동일한 무기물 첨가조건에서 유사한 가소도를 갖게 하는데 필요한 량은 fluid들의 종류에 따라서 상당한 차이가 있었다. 특히 PDMS는 점도는 낮지만 분자량이 커서 많은 량이 첨가되어 기계적 특성저하가 크게 일어났다. 코로나 처리후 발수성 회복특성은 fluid들의 분자크기와 반응기의 종류에 따라 상당히 영향을 받았으며 분자가 클수록 초기회복속도는 다소 느려도 최종의 상시발수성은 다소 높게 유지되었으며 2일 이내에 거의 초기 접촉각으로 회복되었다. 내아크성은 무게손실이 적을수록 오차범위도 작은 안정된 특성을 보였으며 fluid들의 종류에 따른 무게손실의 차이는 크지 않았다. 트래킹 방전에 의한 무게 감소는 fluid의 분자가 크면서 페닐기를 가진 fluid들이 첨가된 고무가 우수한 특성을 보였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2002.11a
• /
• pp.51-54
• /
• 2002

폴리머 애자용 Shed 재료의 전기방전에 대한 열화내성과 표면발수성은 제품의 장기성능에 있어서 가장 중요한 물성들이다. 그러나 무기보강재의 첨가량이 많아 무결점 성형성을 만족하도록 하기 위해서 Process Oil의 사용이 불가피한데 사용하는 오일의 종류와 양에 따라 옥외절연물의 장기성능에 영향을 주는 표면발수성이나 방전내성은 크게 차이가 나는 것으로 밝혀져 있다. 본 논문에서는 화학적 구조와 점도가 다른 몇 종의 hydroxy silicone oil(HS 오일)을 혼련 (kneading) 하는 과정에 첨가하여 이들 오일의 종류와 양이 고무의 기본적인 물성, 발수성, 방전열화내성， 내트래킹성 등에 어떻게 영향을 주는가를 조사하였다. 코로나 처리시간에 따라서 접촉각의 저하정도와 코로나 처리 후 경과시간에 따른 발수성의 회복특성을 조사하였다. HS 오일의 접도에 따라 초기발수성, 발수성 회복특성의 차이가 많았다. 점도가 낮을수록 초기 발수성 저하는 크며 회복속도는 빠른 반면 점도가 높을수록 초기 발수성 저하는 작은 반변은 발수성 회복속도는 다소 느리게 나타났다 내트래킹성 결과는 점도가 높을수록 우수한 특성을 보였다. 결론적으로 폴리머 애자용 실리콘고무의 컴파운딩에서 실리콘오일의 선택은 성형작업성, 발수성회복특성, 열화내성 외에 가격 등을 고려하여 최적화가 필요하다.

• Journal of the Society of Disaster Information
• /
• v.20 no.3
• /
• pp.584-592
• /
• 2024

Purpose: The biggest concern in cold wave situations is that the fire extinguishing water initially supplied through dry pipes with empty pipes consumes enthalpy and freezes as it rapidly approaches the surface temperature of steel pipes that have been exposed to sub-zero outdoor air for a long time. It has no choice but to be. Method: Therefore, the study found that ice crystals were generated during transport, making it difficult to transport fire extinguishing water, and as a result of the review, when the heat load passed through the piping material, the heat loss per unit length from the piping to the surroundings was 0.946. Results: When calculating the volume of the main pipe, it was calculated that the fire extinguishing water supplied at a temperature of 15 degrees from the underground pipe would have a volume of 3.33m³ to reach the first branch point. If we calculate the heat required until this volume reaches below zero, we get 316.350 kcal. When the results were reviewed using the related formula, the time required for the fire extinguishing water to completely freeze up to the first branch of the steel pipe was found to be 3,412 seconds. Conclusion: Fire-fighting water, which must reach from the main pipe to the branch pipe and nozzle in good condition, must minimize heat loss through the pipe surface along the transfer path. To achieve this, it is necessary to supplement insulation of the main pipe and branch pipes. In this study, the use of inorganic perlite material or flame-retardant rubber foam insulation was proposed through analysis of insulation properties.

• Proceedings of the KIEE Conference
• /
• 1995.07c
• /
• pp.1058-1060
• /
• 1995

In this paper, we studied the tracking characteristics of silicone rubbers that differed in the degree of crosslinking. As the tracking method, we adopted ASTM D 2303 and Merry-Go-Round(MGR) test method. It was found that the higher the degree of crosslinking, the better tracking characteristics. In these two test methods, specimens showed similar tendency of performance variation according to the degree of crosslinking. However the degradation phenomena were very different. As for MGR method, only the color of specimens' surface changed without any erosion or tracking path on them. On the contrary, the specimens subjected to ASTM D 2303 test method showed severe erosion.