• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권10호
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• pp.465-472
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• 2002

This paper presents a study on the aging and recovery of HTV (high temperature vulcanized) silicone rubber used for outdoor insulators. UV irradiation, corona discharge and water immersion were employed as factors of the artificial aging. The effects of changes derived from these stresses on the tracking and arc resistance of silicone rubber were examined. We have investigated the aging phenomena of HTV silicone rubber by the above stresses using the surface energy calculation with contact angle measurement, solvent-extraction, and surface/volume resistivity and so on. These results showed that UV irradiation and corona discharge lead to nearly the same surface oxidation, but the percentage change of mobile low molecular weight by these stresses was different. Furthermore, the oxidized layer induced under UV irradiation restricted the recovery of hydrophobic surface. Water immersion little lowered hydrophobicity level and leaded to a loss of tracking and arc resistance. The degradation mechanism based on our results was discussed.

• 멤브레인
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• 제28권3호
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• pp.169-179
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• 2018

본 연구는 역삼투막의 물리-화학적 표면 개질을 통하여 친수성 증가에 따른 내오염성 및 내염소성을 향상하고자 하였다. 자외선조사로 상용막 표면을 활성화한 후 실란 커플링제를 sol-gel법으로 개질하여 염소에 대한 민감도를 낮춰 폴리아마이드 활성층을 보호하여 내염소성을 향상시켰다. 또한, 에폭사이드의 개수가 다른 PGPE, SPE 두 종류의 에폭시로 코팅 후 에폭사이드의 개환반응으로 내오염성을 향상시켰으며, 표면 개질 조건은 접촉각과 FT-IR, XPS 분석을 통해 최적화하였다. 실란-에폭시 개질막의 오염성 평가 결과 투과도 감소율이 상용막보다 약 1.5배 감소하였고, 내염소성 평가 결과 $20,000ppm{\times}hr$에서도 염제거율이 90% 이상 유지되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집
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• pp.447-450
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• 2002

Recently polymeric insulators and arresters are being used for outdoor high voltage applications. Polymeric insulators for transmission line have significant advantages over porcelain and glass insulators, especially for ultra-high voltage(UHV) transmission lines. Their advantages are light weight, vandalism resistance and hydrophobicity. Polymeric insulator kind are a relatively new technology, but their expected life is still unknown. In this paper, the material property for polymeric insulating material such as silicone rubber and EPBM is investigated by cross-link time and the relation between tracking resistance and W resistance is analyzed by IEC 60587 and W aging experiment.

• 한국산림과학회지
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• 제88권4호
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• pp.469-476
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• 1999

본 연구는 증가되는 UV-B 환경에 대한 양수(陽樹)와 중성수(中性樹)의 생장 및 생리적 반응을 탐구하고자 자작나무(Betula platyphylla var. japonica Hara)와 물푸레나무(Fraxinus rhynchophylla Hance)의 유묘(幼苗)를 대상으로 14주 동안 3 수준의 UV-B(ambient UV-$B_{BE}$, ambient+3.2, +$5.2\;KJ\;m^{-2}s^{-1}$) lamp가 설치된 야외포장에서 실시되었다. 자작나무와 물푸레나무 유묘의 수고생장(樹高生長), 근원경생장(根元徑生長), 엽면적(葉面積) 및 건물생산(乾物生産)은 UV-B 증가에 의하여 감소되었다. UV-B 증가에 의해 물푸레나무 유묘 잎의 기공저항(氣孔低抗)은 커졌으며, 엽록소(葉綠素), carotenoid 함량의 감소는 자작나무에서 보다 물푸레나무에서 더 뚜렷하였다. UV-B 흡수물질(吸收物質)의 현저한 증가는 나타나지 않았지만 자작나무에 비해 물푸레나무의 경우 다소 증가하는 경향이었다. 이러한 결과들은 UV-B 증가 환경에 대한 공시 두 수종의 생리적(生理的), 생화학적(生化學的) 반응이 다르다는 것을 의미한다.

• 한국산학기술학회논문지
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• 제20권11호
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• pp.527-536
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• 2019

본 연구에서는 PTT BCF의 열과 자외선에 의한 취화거동과 분산염료의 열 및 자외선에 의한 퇴색거동을 연구하였다. 염료의 퇴색과 PTT BCF의 취화를 억제시킬 수 있는 첨가제를 방사과정에서 첨가하여 그 효과를 알아보았다. PTT BCF의 열처리 이후 취화거동은 열처리 온도와 노출시간이 증가할수록 취화현상이 가속화되어 시료의 인장강도 저하가 두드러졌다. 시료가 120℃까지의 온도에 노출하였을 때는 인장강도의 저하가 크지 않으나 그 이상의 온도인 150℃에서는 노출시간에 비례하여 급격한 인장강도 저하를 보였다. 열에 의한 취화는 산화방지 첨가제가 높은 온도에서는 그 효과가 안정적이지 않으며 산화반응이 급격하였다. 열처리 이후 시료의 퇴색은 열처리 온도가 증가할수록 K/S 값이 감소하였고, 노출시킨 시간이 증가할수록 퇴색되는 경향이 강하게 나타났다. 특히 고온으로 갈수록 열에 의한 퇴색 거동이 급격하게 증가하였으며 열퇴색 억제제가 그 효과를 발휘하지 못했다. 자외선 조사 이후 PTT BCF의 취화거동과 퇴색거동을 인장강도 변화와 K/S 값 변화로 각각 살펴보았다. 자외선 조사에 따른 취화는 열처리 시의 취화보다 더 크게 나타났으며, 특히 장시간 동안 노출된 경우 인장강도의 저하가 급격하였다. 또한 K/S 값의 변화 역시 온도와 노출시간이 증가할수록 퇴색거동이 강하게 나타났다. 시료의 취화거동과 퇴색거동은 자외선 조사의 경우가 더 가혹하게 나타났다. 열 및 자외선 모두가 분산염료의 퇴색에 영향을 주며, 자외선 조사는 같은 온도에서 노출했을 때에 비해 아주 높은 퇴색 속도를 보였다. 결론적으로 열과 자외선에 의한 퇴색과 취화는 특정 산화방지제와 자외선흡수제에 의해 다소 억제되어 저하되었다.

• 한국정밀공학회지
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• 제27권10호
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• pp.23-28
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• 2010

Resistance trimming and cutting processes of printed circuit board by making use of high power UV laser with nano-second pulse width have been proposed and investigated experimentally. Also laser-based application system with high flexibility and complex has been designed and adopted power controller, auto beam size control, auto-focusing and control program developed for ourselves. The function of each module shows that they can be reliable for industrial equipments. Resistance trimming method used a plunge and double cut process with $20{\mu}m$ spot size beam. Results show that double cut process is more effective to control resistance trimming in precision than plunge cut process.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.243-247
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• 2003

The effect of accelerated weathering(UV) on three type of ethylene propylene diene monomer(EPDM) composite used for higher voltage insulator were investigated by weather-emoter. For weatherability of EPDM composite, surface resistance, dielectric breakdown strength, change of contact angle, surface composition were measured according to UV accelerated weathering time. From the resort of the measurement of surface resistivity, contact angle of EPDM composite decreased and showed chalking and cracking phenomenon when UV weathweing time was for 1500 h and 2000 h. The analysis of surface atomic composition indicated that surface aluminiu(Al) content was detected due to chalking phenomenon after 1500 h of UV weathering, Oxygen content of all composite increased due to the oxidation.

• 한국가구학회지
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• 제26권4호
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• pp.428-434
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• 2015

In this study, we received each wood plastic composites (WPC) from three manufacturers. These WPCs were evaluated regarding their physical and mechanical properties of both before and after accelerated weathering by ultraviolet (UV) irradiation. The total time of exposure of the WPCs to UV irradiation was 1800 h. The water absorption, volumetric swelling and shrinkage of WPCs did not affected by UV irradiation. Among the mechanical properties, there was no significant differences in bending strength and screw withdrawal resistance of UV treated WPCs compared with those of reference WPCs. However, surface hardness of WPCs showed decrease under UV irradiation. Stereoscopic microscopy observation revealed deterioration of the surface layer polymer in all weathered WPCs by UV. Exposure of the WPCs to UV irradiation caused decomposition and disappearance of the polymer layer. From this result, we can estimate that damage of polymer by UV led to a decrease in the surface hardness of the WPCs. The wood flours retained original shape after accelerated weathering by UV irradiation.

• The Plant Pathology Journal
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• 제17권5호
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• pp.271-275
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• 2001

Phytoalexin scoparone (6,7-dimethoxycoumarin) was induced in flavedo tissue of lemon fruit inoculated with Penicillium digitatum during heat treatment for 3 days at $36^{\circ}$. The compound was also induced in the flavedo tissue after UV illuminatiion. Induction of scoparone was deteected in the flavedo tissue by histological analysis. This fluorescent scoparone accumulated only on the 4-5 layers of cells adjacent to the inoculation site. Preinoculation with P. digitatum and subsequent heat-treatment induced resistance in the lemon fruit tissues after challenge-inoculation at the site of the first infection. the data obtained in the study suggest that lemon fruit acquired resistance against P. digitatum parallel with the scoparone production at the infection site.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 C
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• pp.434-436
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• 2000

In this study, we investigate the optical characteristics of merocyanine dye Langmuir-Blodgett(LB) film using the oscillation characteristics of quartz crystal. As results, the resistance and frequency shift at the parallel resonance under the UV irradiation is to be going down. This behaviour of resistance and frequency is different from the case of general mass adsorption into the organic film on the quartz crystal. Generally the frequency decrease of quartz crystal oscillator, which has been considered as mass loading, goes along with the resistance increase. Thus it has been suggested that the J-aggregate dissociation in merocyanine dye LB film by UV irradiation give rise to transformation of oscillation characteristics of quartz crystal.