• Journal of Electrical Engineering and Technology
• /
• 제11권3호
• /
• pp.690-698
• /
• 2016

In this paper, a study is carried out to investigate the dielectric, physical and chemical properties of Palm Oil (PO) and Coconut Oil (CO) under open thermal ageing condition. The type of PO used in this study is Refined Bleached and Deodorized Palm Oil (RBDPO) Olein. The ageing experiment was carried out at 85 ℃ and 115 ℃ for 1, 3, 5, 7 and 14 days. Several parameters were measured such as AC breakdown voltage, dielectric dissipation factor, relative permittivity, resistivity, viscosity, moisture and acidity throughout the ageing duration. Based on the study, it is found that there are no significant changes on the AC breakdown voltages and relative permittivities for both RBDPO and CO. At ageing temperature of 115℃, there are clear reduction trends of dielectric dissipation factor for CO and resistivities for most of RBDPO. On the other hand, no clear trends are observed for viscosities, moisture and acidities of RBDPO and CO throughout the ageing duration.

• 한국소음진동공학회논문집
• /
• 제24권7호
• /
• pp.562-568
• /
• 2014

This study aimed to identify changes in the physical properties of artificial mineral-fiber materials used as building insulation that had been installed in the outer walls of buildings for a long time. To achieve this goal, glass fiber and rock wool were collected from outer walls in actual buildings and their acoustic and thermal performances were measured. These were compared with measurements from similar products manufactured recently. The results showed that old, used samples had a lower sound absorption coefficient compared to recently manufactured materials. The old samples also displayed increased compressibility compared to new materials. For example, the compressibility difference for glass wool was 7.32 mm. Old samples had a dynamic stiffness $1.28MN/m^3$ higher than new material samples. The thermal conductivity of both old and new samples increased within creasing temperature. They showed similar results at temperatures between 0 and $20^{\circ}C$.

• Corrosion Science and Technology
• /
• 제7권5호
• /
• pp.269-273
• /
• 2008

It is known that the fluoric resin has the most outstanding properties in the extremely acidic environment of high temperature. However, this resin is the thermal hardening type that needs long time heat treatments above $250^{\circ}C$. It's impossible to use in situ in the extremely acidic environment such as a huge FGD ductworks or industrial chemical tanks. Furthermore, even the natural hardening type fluoric coatings which can be hardened less than $120^{\circ}C$ can not be applied to the highly acidic environmental plants because of its chemical resistance. In this study, new fluoric coatings that has excellent thermal resistance, chemical resistance and corrosion resistance has been developed in order to solve above problems and to be applied to the large plant structures in the field. These newly developed coatings are organic and inorganic composite type that have fluoric rubber(100 wt%), fluoric resin(5~50 wt%), oxalates(5~30 wt%), inorganic fillers mixed with plate-type and bulk-type solids(20~150 wt%), hardeners(0.5~5 wt%), and hardening hasteners(0.1~3 wt%). The best chemical and physical properties of these coatings are acquired by variation of adhesive reinforcement agents, dispersants, leveling agents. Mixing ratios of plate-type and bulk-type inorganic fillers influence the thermal properties, abrasive resistance and chemical infiltration properties of coatings. The mixing control is also very important to have homogeneous surface and removing inner voids of coatings.

• Journal of the Korean Wood Science and Technology
• /
• 제36권6호
• /
• pp.1-12
• /
• 2008

주요 국산재의 여러 가지 응용물성을 지난 3년에 걸쳐 조사하였다. 전보(강 외 4인 2008, 변 외 5인 2008)에 이어 본보에서는 우리나라의 활엽수 주요 수종인 백합나무, 거제수나무, 오동나무를 재료로 사용하였다. 매년 동일한 장치와 실험조건으로 실험하였기 때문에 모든 수종에 대한 결과를 상호 비교 할 수 있었다. 수분흡착성 실험은 80메시 목분을 이용하였으며, 넓은 범위의 상대습도조건에 따른 평형 함수율과 흡착등온선을 구하였다. 열전도율과 열확산률은 열선열전도장치를, 전기의 부피저항률과 저 항은 고전기저항계를 이용하여 측정하였다. 정목재와 판목재의 열적 전기적 특성차이가 관찰되었는데 이는 해부학적 차이에 의한 것으로 보인다. 음향적 성질은 음향측정시스템을 사용하여 동적탄성률, 내부마찰을 측정하였다. 본 논문의 결과들은 목재구조물 설계, 휴대용 목재수분계 보정, 음향적 성질 등에 필요한 기본 자료를 제공한다.

• 시멘트 심포지엄
• /
• 통권49호
• /
• pp.31-32
• /
• 2022

본 연구는 비탄산염 순환자원을 원료로 활용하여 석회석 사용량을 최소화할 수 있는 저열 시멘트 제조기술 개발을 위하여 일반 포틀랜드 시멘트(OPC)와 시중의 저열 포틀랜드 시멘트(LHC)의 물성을 비교하여 차이를 분석하기 위하여 모르타르를 배합비에 차이를 두고, 슬럼프, 강도, 내구성, 단열 특성 등의 물성평가를 실시하여 검토를 진행하고 있다.

• 한국지하수토양환경학회:학술대회논문집
• /
• 한국지하수토양환경학회 2001년도 추계학술발표회
• /
• pp.111-114
• /
• 2001

Thermal desorption process is valuable for the remediation of oil contaminated site. The system is physical separation process by volatizing oil contaminants from soil matrixes and is not designed to provide high levels of oil destruction. The process is not incineration, because the decomposition of oil materials is not the desired result, although some decomposition may occur. The physical and chemical properties that influence the design and operation of the system include boiling points, soil sorption characteristics, aqueous phase solubility, thermal stability, contaminating oil concentration, moisture contents, particle size distribution and etc.

• 대한안전경영과학회지
• /
• 제10권4호
• /
• pp.121-126
• /
• 2008

The effect of $Al(OH)_3$ on physical, thermal, and retardant property of rubber was studied. It was analyzed by statistical experimental design method with one way array to confirm the effect of factors. Physical characteristics, thermal pyrolysis temperature, and combustion time were considered as the properties. The amount of $Al(OH)_3$ addition was chosen as significant parameter. As the result of ANOVA analysis, thermal pyrolysis temperature increased and combustion time decreased with increasing of $Al(OH)_3$.

• Steel and Composite Structures
• /
• 제46권5호
• /
• pp.637-647
• /
• 2023

Nonlinear free vibration and stability responses of a carbon nanotube reinforced composite beam under temperature rising are investigated in this paper. The material of the beam is considered as a polymeric matrix by reinforced the single-walled carbon nanotubes according to different distributions with temperature-dependent physical properties. With using the Hamilton's principle, the governing nonlinear partial differential equation is derived based on the Euler-Bernoulli beam theory. In the nonlinear kinematic assumption, the Von Kármán nonlinearity is used. The Galerkin's decomposition technique is utilized to discretize the governing nonlinear partial differential equation to nonlinear ordinary differential equation and then is solved by using of multiple time scale method. The critical buckling temperatures, the nonlinear natural frequencies and the nonlinear free response of the system is obtained. The effect of different patterns of reinforcement on the critical buckling temperature, nonlinear natural frequency, nonlinear free response and phase plane trajectory of the carbon nanotube reinforced composite beam investigated with temperature-dependent physical property.

• Carbon letters
• /
• 제5권4호
• /
• pp.159-163
• /
• 2004

The polymer-ceramic hybrid, known as 'ceramer', was synthesized by a sol-gel process by incorporating different amount of alkoxide as source of silicon in resorcinol-formaldehyde in presence of basic catalyst to get different percentage of silicon in ultimate carbonized composites. FTIR of the ceramer confirms that it is a network of Si-O-Si, Si-O-$CH_2$ and Si-OH type groups linked with benzene ring. Different amount of silicon in the ceramer exhibits varying temperature of thermal stability and lower coefficient of thermal expansion as compared to pure resorcinol-formaldehyde resin. The lower value of CTE in ceramer is due to existence of silica and resorcinol -formaldehyde in co-continuous phase. Unidirectional composites prepared with ceramer matrix and high-strength carbon fibers show lower value of flexural strength at polymer stage as compared to those prepared with resorcinol-formaldehyde resin. However, after heat treatment to $1450^{\circ}C$, the ceramer matrix composites show large improvement in the mechanical properties, i.e. with 7% silicon in the ceramer, the flexural strength is enhanced by 100% and flexural modulus value by 40% as compared to that of pure resorcinol-formaldehyde resin matrix composites.

• 폴리머
• /
• 제37권6호
• /
• pp.730-735
• /
• 2013

제지 공정에 있어서 지력 증강제로 사용되는 polyamide-epichlorohydrin(PAE)를 함유한 폴리비닐알코올(PVA)의 물성을 살펴보았다. PAE 첨가로 인하여 PVA의 용융과 결정화 열량이 감소될 뿐만 아니라 X-ray 결정 피크의 면적이 감소되는 것으로 보아 PAE에 의하여 PVA 가교가 진행됨을 알 수 있었다. 이러한 현상은 가수화도가 높은 PVA의 경우 더 두드러짐을 확인하였다. 하지만, 열처리에 의하여 PVA의 결정화가 일어나는 것으로 보아 PAE에 의한 PVA의 가교는 화학적 가교보다는 상대적으로 결합력이 약한 물리적 가교임을 알 수 있었다. PAE에 의한 PVA의 가교 및 결정화는 PVA의 열안정성, 기계적 강도를 증가시켜 이를 제지 공정의 지력 증강제로 사용할 경우, 종이의 건조 및 젖음 지력 향상에 효과가 있음을 알 수 있었다.