• Journal of Welding and Joining
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• 제24권2호
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• pp.57-63
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• 2006

In this study, the curing kinetics and thermal degradation of underfill were investigated using differential scanning calorimetry (DSC) and thermo gravimetry analysis (TGA). The mechanical and thermal properties of underfill were characterized using dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA). Also, we presented on underfill dispensing process using Prostar tool. The non-isothermal DSC scans at various heating rates, the exothermic reaction peak became narrower with increasing the heating rate. The thermal degradation of underfill was composed of two processes, which involved chemical reactions between the degrading polymer and oxygen from the air atmosphere. The results of fluidity phenomena were simulated using Star CD program, the fluidity of the underfills with lower viscosity was faster.

• 한국산업보건학회지
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• 제18권3호
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• pp.224-238
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• 2008

The aim of this study is to confirm the physicochemical property and hazard of thinner (012), which is a diluent of enamel paint used for floor coating for waterproofing and oil painting for the outer wall. The literatures of physicochemical property and hazard of thinner were surveyed and its physicochemical property were evaluated. And then, the inhalation toxicity of thinner affecting the central nervous system and reproductive organs in rats were examined by subchronic (6 h./day. 5 days/ week for 13 weeks) inhalation test. 1) According to the 13-week subchronic inhalation test, there were no significant changes in clinical test and body weight. However, a significant evidence of toxicity was observed in the hematological test and organ weight such as heart, kidney, liver and brain (p<0.01) in the 200 ppm and 1,000 ppm exposure groups in a dose response manner. In the histopathology analysis, there were no significant evidence of toxicity. Therefore, thinner was not classified as an organ targeted toxic agent. In case of Harmfulness, it could be classified as a chronic toxic agent 3($500 ppm/4hr, rat). 2) The reproductive toxicity such as extension of the period of estrous cycle, reduction of serum estradiol concentration and increase of frequency of the abnormal sperm was observed in the 1,000 ppm exposed animals. 3) The result of the physicochemical property of the test material showed that the specific gravity was 0.793, boiling point $155.8^{\circ}C$, steam pressure 2.1 kPa, ignition point $34.5^{\circ}C$, and spontaneous ignition point $280^{\circ}C$. The endothermic and exothermic values were 371.4 J/g and 159.1 J/g. respectively. The explosion limit was 214 mg/l. These data showed that thinner could be classified as an explosion agent level 1.2 and ignitive liquid agent 3 ($23-60^{\circ}C$) according to the notification No. 2008-1 of the Labor Ministry, "Classifying Standard of Chemical Materials."

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.259-259
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• 2009

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, they are not suited to outdoor insulator by reason of being not good hydrophobic. RTV has a good property of hydrophobic and ATH has characteristic obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained nano size ATH coat on surface of engineering plastics. In this paper, it compares resistance tracking of the engineering plastic coated RTV with that of non-coated engineering plastic and ATH filled composites performed much better than non-filled composites.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1449_1450
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• 2009

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, they are not suited to outdoor insulator by reason of being not good hydrophobic. RTV has a good property of hydrophobic and ATH has characteristic obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained nano size ATH coat on surface of engineering plastics. In this paper, it compares resistance tracking of the engineering plastic coated RTV with that of non-coated engineering plastic and ATH filled composites performed much better than non-filled composites.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 춘계학술대회 논문집
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• pp.29-29
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• 2010

Surface contamination and leakage current have caused operating problems. A flashover in a substation may result in destruction of an insulator or many others electrical equipment. Engineering plastics have good characteristic (light weight, good productivity and little of void) as compare with epoxy or porcelain insulators. Outdoor insulator must have resistance to contamination. However, it isn't suited to outdoor insulator because it is not hydrophobic. RTV(Room temperature vulcanizing) has a good property of hydrophobic and micro-filler. nano-filler have characteristics of obstructing exothermic reaction. In order to reduce the incidence of insulator flashover and damage, the silicon rubber contained with micro, nano-filler coating on surface of engineering plastics. In this paper, it compares tracking resistance, leakage current of the engineering plastic coated RTV with that of non-coated engineering plastic. And filled-composites performed much better than non-filled composites.

• 한국세라믹학회지
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• 제49권2호
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• pp.167-172
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• 2012

Fine diamond powders are synthesized with a 420 ${\phi}$ cubic press and stack-cell composed of Kovar ($Fe_{54}Ni_{29}Co_{17}$) (or Kovar+7 ${\mu}m$-thick Zn electroplated) alloy and graphite disks. The high pressure high temperature (HPHT) process condition was executed at $1500^{\circ}C$ for 280 seconds by varying the nominal pressure of 5.7~10.6 GPa. The density of formation, size, shape, and phase of diamonds are determined by optical microscopy, field emission scanning electron microscopy, thermal gravimetric analysis-differential thermal ammnlysis (TGA-DTA), X-ray diffraction (XRD), and micro-Raman spectroscopy. Through the microscopy analyses, we found that 1.5 ${\mu}m$ super-fine tetrahedral diamonds were synthesized for Zn coated Kovar cell with whole range of pressure while ~3 ${\mu}m$ super-fine diamond for conventional Kovar cell with < 10.6 GPa. Based on $750^{\circ}C$ exothermic reaction of diamonds in TGA-DTA, and characteristic peaks of the diamonds in XRD and micro-Raman analysis, we could confirm that the diamonds were successfully formed with the whole pressure range in this research. Finally, we propose a new process for super-fine diamonds by lowering the pressure condition and employing Zn electroplated Kovar disks.

• 한국재료학회지
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• 제17권7호
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• pp.382-385
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• 2007

[ $LaFeO_3$ ] powders were prepared as the oxidation catalyst materials to reduce the emission of particulate matters from diesel engine and their catalytic effects on the oxidation of carbon were investigated. Solution combustion method was employed for the powder synthesis, which uses highly exothermic and selfsustaining reactions. In this study $LaFeO_3$ powders were synthesized at $400^{\circ}C$ as varying the ratio ($\Phi$) of fuel (citric acid) and oxidizer (metal nitrate), and their phase and carbon ignition property were examined. As $\Phi$ decreases, the crystallinity of synthesized $LaFeO_3$ powders enhanced. By calcining at $700^{\circ}C$, all the powders synthesized at various $\Phi$ fully crystallized. The calcined $LaFeO_3$ powders showed carbon ignition temperature as low as $501{\sim}530^{\circ}C$, which implied the decrease of the ignition temperature by $120{\sim}150^{\circ}C$.

• 한국산학기술학회논문지
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• 제9권3호
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• pp.593-598
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• 2008

브레이크 마찰재의 구성성분 중 기존에 사용되던 무기 충진재인 $BaSO_4$ 대신에 고로슬러지와 그 산화철에 일련의 환원과정을 행하여 얻은 환원분철을 10%, 20%, 30%씩 첨가하면서 몇 종류의 마찰재를 제작하였다. 이 마찰재들에 대해 기본 물성시험, 브레이크 다이마모미터를 사용한 마찰성능 시험 등을 행하였다. 그리고 고가의 충진재인 $BaSO_4$를 환원분철로 대체하여 마찰재에 첨가한 경우, 발열온도, 마모 등의 마찰특성이 우수한 환원분철의 첨가량은 10%이었다. 고로슬러지나 환원분철 시편에서 고로슬러지와 환원분철의 첨가량이 증가할수록 마찰재의 전단강도와 접착강도는 감소하나 모두 마찰재로서의 적용에는 충분한 강도를 나타내었다.

• Composites Research
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• 제18권4호
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• pp.14-20
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• 2005

방향족아민 경화제의 벤젠링 사이의 관능기 변화가 반응특성, 기계적특성 및 열적특성에 미치는 영향을 고찰하기 위하여 범용 에폭시수지인 DGEBF와 방향족아민 경화제 DDM, DDS 각각을 1:1의 당량비로 혼합하여 동일한 조건으로 경화하였다. 그 결과 에폭시수지 경화물의 특성은 경화제의 벤젠링 사이의 관능기 구조에 따라 매우 큰 영향을 받았다. 즉, 벤젠링 사이에 길이가 길고 bulky한 술폰기를 포함한 DDS는 반응성, 열안정성, 밀도, shrinkage($\%$), 선팽창계수, 인장탄성율. 인장강도, 굴곡탄성율, 굴곡강도의 값이 벤젠링 사이에 메틸기를 가지는 DDM 경화물계 보다 높게 나타났지만, epoxide기의 전환율, 유리전이온도의 값은 낮게 나타냈다. 이것은 술폰기의 강한 전기음성도와 메틸기의 전기 양성적인 repulsive한 성질의 차이에 의한 영향인 것으로 판단된다. 굴곡 파단면의 관찰 결과는 DDS 경화물계의 각개 grain이 불규칙적으로 분포되어 있음을 확연하게 보여준다.

• 조명전기설비학회논문지
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• 제20권8호
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• pp.71-79
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• 2006

페놀수지 표면에서의 트래킹 방전에 대한 화재원인을 규명하기 위하여 검증실험, FT-IR, DTA, 사진촬영 등의 다양한 방법으로 분석하였다. 페놀수지는 유기질 절연재료 중 저전압기기의 외함재료로 가장 많이 이용된다. 본 실험에서는 외부열에 의해 탄화질로 변화되는 것과 전기적 원인에 의해 흑연질이 되는 것에 대해 재료분석을 통한 방법으로 규명하였다. FT-IR을 이용하여 표면방전에 의해 탄화된 시료는 $150[^{\circ}C]$에서 열처리된 시료로부터 약 $1730[cm^{-1}]$ 부분과 $1680[cm^{-1}]$부근의 적외선흡광피크를 확인하였다. DTA를 이용하여 페놀수지는 약 $450[^{\circ}C]$ 부근에서 발열피크가 나타났으며, 방전에 의해 탄화된 재료는 약 $610[^{\circ}C]$ 부근에서 발열피크가 나타나는 것을 알 수 있었다. 이로써 전기화재원인을 규명하는 것이 가능하게 되었다. 이 결과들로부터, 전기화재의 예방과 국민의 생명과 재산을 지키는 중요한 자료가 될 것으로 기대된다.