• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제50권10호
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• pp.494-499
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• 2001

The effects of accelerated Ultraviolet (UV) radiation on High temperature vulcanized (HTV), Room temperature vulcanized (RTV) silicone rubber and two types of ethylene propylene diene terpolymer (EPDM) used for composite insulator were investigated by hydrophobicity class (HC), surface voltage decay after corona charging, SEM-ES, FTIR and XPS. The contact angle in two kinds of silicone rubber was scarcely change, but EPDM occurred to the loss of hydrophobicity followed by surface cracking and chalking. The surface voltage decay on UV-treated silicone rubber and EPDM showed a different decay trend with UV treatment. EDS and XPS analysis indicated that the oxygen content increased with UV treatment time in all samples. For silicone rubber, the oxidized groups of inorganic silica-like structure increased with UV treatment time. The oxidized carbon of C=O, O=C-O in EPDM increased. These oxidized surface for each material had different electrostatic characteristics, so deposited charges were expected to have different impacts on their surface hydrophobicity. The degradation mechanism based on our results was discussed.

• 분석과학
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• 제19권4호
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• pp.323-332
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• 2006

This paper discusses several low-temperature heat-tranfer fluids, including water-based inorganic salt, organic salt, alcohol/glycol mixtures, silicones, and halogenated hydrocarbons in order to choose the best heat-transfer fluid for the newly designed direct contact refrigeration system. So, it contains a survey on commercial products such as propylene glycol and potassium formate as newly used in super market and food processing refrigeration. The stability of commercial fluids at the working temperature of $-20^{\circ}C$ was monitored as a function of time up to two months. And organic and inorganic compositions of candidate fluids were obtained by analytical instruments such as ES, XRF, AAS, ICP-AES, GC, and GC-MS. Analysis results indicate that commercial propylene glycol is very efficient and safe heat transfer fluids for the direct cooling system with liquid phase.

• Journal of the Korean Wood Science and Technology
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• 제41권4호
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• pp.276-286
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• 2013

본 연구에서는 30, 60, $90^{\circ}C$의 증류수를 이용하여 거대억새 내에 존재하는 무기성분을 제거한 후 원료의 화학적 변화 및 열분해 특성 변화를 관찰하였다. 증류수 처리 온도가 증가할수록 거대억새의 탄소함량은 44.0% (control)에서 46.2% ($90^{\circ}C$ 처리)로 증가하였으며 산소함량은 49.3% (control)에서 47.0% ($90^{\circ}C$ 처리)로 감소하였다. 또한 증류수 처리 온도가 증가함에 따라 거대억새 내 회분 함량은 4.6% (control)에서 3.2% ($90^{\circ}C$ 처리)로 점차적으로 감소하는 것을 확인할 수 있었다. 주요 단당류 정량 분석 결과 무기성분 제거에 따른 시료의 당 손실은 없는 것으로 확인되었으며 결정화 영역 분석을 통해 셀룰로오스/헤미셀룰로오스 영역의 구조적인 변형도 일어나지 않았음을 알 수 있었다. 무기성분 정량 결과 거대억새 내에는 칼륨(5,644 ppm), 인(3,995 ppm), 마그네슘(1,403 ppm), 칼슘(711 ppm) 등이 상당량 존재하는 것으로 나타났다. 열중량 분석을 통해 거대억새 내 무기성분 함량이 감소할수록 최종적으로 생성되는 탄의 수율이 감소함을 확인하였다. 또한 시료 내 무기성분 함량이 감소함에 따라 최대반응온도($T_M$) 및 최대분해율($V_M$)이 증가하는 경향을 보였다.

• 펄프종이기술
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• 제39권5호
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• pp.45-51
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• 2007

This study was carried out to investigate various heavy metal contents in packaging papers by pre-treatments for ICP-ES (Inductively Coupled Plasma Emission Spectrometry) analysis. Pre-treatment methods of heavy metals in this study include extraction, migration and decomposition methods (dry ashing, $HNO_3-HClO_4-HF,\;HNO_3,\;and\;H_2SO_4-HNO_3$). Test results were compared with conventional extraction (water) and migration (3% acetic acid) methods. The five representative heavy metals (Cd, As, Pb, Cr and Hg) were analyzed. For Cd, Hg, and As, the results were below detection limit of the instrumental technique. It was considered that the migration test was a better method compared to extraction test, but all the decomposition methods showed much higher detection values than the extraction or migration test. In case of recycled corrugated containers, 3% acetic acid solution extracted about 25% of chromium and 30% of lead compared to the content by decomposition methods. Among all decomposition methods, the nitric acid - perchloric acid - hydrofluoric acid treatment brought a slightly higher detection value than others, but there was no significant difference among them except sulfuric acid - nitric acid method.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.465-469
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• 2006

Pre-treatment methods to determine various heavy metal contents in packaging papers were investigated by ICP-ES (Inductively Coupled Plasma Emission Spectrometry) analysis. Pre-treatment methods utilized in this study include dry ashing and decomposition methods ($HNO_{3-}HClO_{4-}HF,\;HNO_{3},\;and\;H_{2}SO_{4-}HNO_{3}$). They were compared with the conventional extraction (water) and migration (3% acetic acid) methods. The five representative heavy metals (Cd, As, Pb, Cr and Hg) were analyzed. For Cd, Hg, and As, the results were below detection limit of the instrument. In case of Cr and Pb, the migration test is considered to be a better method compared to the extraction test, but all pretreated methods showed much higher detection efficiency than the extraction or migration test. However, the detection ratio between the migration test and decomposition methods was different. Among all decomposition methods, the nitric acid - perchloric acid - hydrofluoric acid treatment brought a slightly higher detection value than others, but there was no significant difference among them except sulfuric acid - nitric acid method. Concerning Pb, the sulfuric acid - nitric acid method showed a low detection efficiency compared to other decomposition methods. The sulfuric acid - nitric acid method is, thus, not considered to be a suitable analysis method for Pb in packaging papers.