• 열처리공학회지
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• 제22권4호
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• pp.228-233
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• 2009

In order to predict the temperature distribution of stainless steel strip in Bright Annealing (BA) furnace, we performed the analysis of heat transfer and fluid flow using STAR-CCM+. The analysis model included unsteady fluid flow, heat transfer with radiation and moving grid. Two kinds of radiative properties, emissivity and reflectivity, were applied to the stainless steel strip, one is constant and the other is variable with time. As we call, the BA furnaces of stainless steel strip have two different types, muffle and no-muffle. The using of muffle type has been faced with some problems such as rising in material price and shortening of life cycle, etc. So the development of no-muffle type BA furnace is very important in order to save energy cost, lower environmental load and increase the productivity. The designed (or expected) temperature of stainless steel strip coming out of BA furnace was about $1065^{\circ}C$ while the environment temperature maintains around $1100^{\circ}C$. The result of our calculation was very close (or similar) to design temperature, and the application of radiative properties variable with time produced more accurate result than applying constant ones.

• 한국전산유체공학회지
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• 제16권1호
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• pp.22-29
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• 2011

In this study, the glass fiber drawing from a silica preform in the furnace for the optical fiber manufacturing process is numerically simulated by considering the radiative heating of cylindrically shaped preform. The one-dimensional governing equations of the mass, momentum, and energy conservation for the heated and softened preform are solved as a set of the boundary value problems along with the radiative transfer approximation between the muffle tube and the deformed preform shape, while the furnace heating is modeled by prescribing the temperature distribution of muffle tube. The temperature-dependent viscosity of silica plays an important role in formation of preform neck-down profile when the glass fiber is drawn at high speed. The calculated neck-down profile of preform and the draw tension are found to be reasonable and comparable to the actual results observed in the optical fiber industry. This paper also presents the effects of key operating parameters such as the muffle tube temperature distribution and the fiber drawing speed on the preform neck-down profile and the draw tension. Draw tension varies drastically even with the small change of furnace heating conditions such as maximum heating temperature and heating width, and the fine adjustment of furnace heating is required in order to maintain the appropriate draw tension of 100~200 g.

• Nuclear Engineering and Technology
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• 제39권6호
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• pp.731-736
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• 2007

Radioactive organic wastes containing acetone, alcohol, and particularly tributyl phosphate (TBP)/dodecane contaminated with uranium are extracted from the PUREX process and the decontamination of related equipment. An evaporation method that utilizes existing DU oxidation apparatuses and ventilation systems and a typical muffle furnace installed with an aspirating system are adopted. A separation method using phosphoric acid especially for the TBP/dodecane waste is also studied and evaluated. The results show that a simple evaporation process is utilizable for wastes containing acetone or alcohol with a lower boiling point. A modified muffle furnace is more appropriate to dispose directly of organic wastes having a higher boiling point, such as TBP/dodecane, without generating a condensed waste solution. It is recommended that, when the uranium concentration of TBP/dodecane waste is much higher than stipulated levels, separation technology should be applied to remove uranium from the mixture. Each type of solvent after separation can then be considered disposable below the regulatory limit in the modified furnace discussed in this study.

• 한국전산유체공학회지
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• 제17권4호
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• pp.16-23
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• 2012

Current display manufacturing processes apply thermal treatment of glass backplanes widely for hydrogen degassing, crystallization of thin-films, tempering, forming, and precompaction. Estimation of the characteristics of transient heating stages and thermal non-uniformities on a single glass substrate or in a stack of glasses are extremely helpful to understand non-homogeneity of mechanical and electronic features of nano/micro structures of end products. Based on simple heat transfer models and using an electric muffle furnace, temperature variations in a glass stack were predicted and measured for glass backplanes of $1.5{\times}1.85m^2$ in size and 0.7 mm in thickness. Except for the period of putting glass backplanes into the furnace, thermal radiation was the major heating mechanism for the treatment and theoretical predictions agreed well to the experimental temperatures on the backplanes. Using the theoretical model, thermal fields for a glass stack of glass-size, $2.2{\times}2.5m^2$, and of the number of sheets, 1 to 12, were calculated for practical design and manufacturing of the muffle furnace for large-scale displays, e.g. up to $8^{th}$ generation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1798-1800
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• 2001

As a batch Type device, this machine is contrive to seal glass plates for plasma BLU (Back Light Unit) by indirect heating from electric heaters. In order to maintain the heating / cooling Chambers clean, this machine uses a muffle formation. The components of the machine are listed bellow.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.94-96
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• 2001

As a batch Type device, this machine is contrive to seal glass plates for plasma BLU (Back Light Unit) by indirect heating from electric heaters. In order to maintain the heating / cooling Chambers clean, this machine uses a muffle formation. The components of the machine are listed bellow.

• 한국전산유체공학회지
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• 제18권4호
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• pp.69-73
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• 2013

Mass manufacturing of optical fiber includes the process of very thin glass fiber drawing by heating and softening the high purity silica preform and applying the draw tension on the softened tip of preform neck-down profile in a draw furnace. In this computational study, this process is numerically modeled with simplified geometry of the draw furnace which is comprised of essential parts such as concentric graphite heater, muffle tube, and insulation surrounding the heater. The iterative computational scheme is employed between one-dimensional model of neck-down profile prediction and two-dimensional axisymmetric thermo-fluid CFD computation of radiative heating and working gas convection. The computational results show the experimentally observed neck-down profile in heated section of preform, while yielding the reasonable values of draw tension and heater wattage. Also, this study analyzes and discusses the effects of heating conditions such as heater length and temperature on several important aspects of glass fiber drawing process.

• Composites Research
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• 제33권6호
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• pp.341-345
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• 2020

열중량분석기를 적용하여 탄소섬유/에폭시 복합재의 구성재 함유량을 평가하기 위한 측정기법을 제시하였다. 시험에 사용된 시료는 탄소섬유/에폭시 토우 프리프레그로 제작된 스트랜드 시편에서 채취하였으며 시간에 따른 시료의 무게 변화를 실시간으로 측정하였다. 또한 전자현미경을 이용하여 수지 제거 여부와 탄소섬유의 열손상 상태를 관찰하였다. 연구결과에 따르면 열중량분석기를 적용하면 기존의 머플로를 적용한 경우에 비해 소량의 시료에 대해서도 시험이 가능하며, 설정 온도와 노출 시간을 제어함으로써 구성재의 함유량을 효율적이고 정량적으로 평가할 수 있음을 알 수 있었다.

• 한국결정성장학회지
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• 제18권6호
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• pp.258-263
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• 2008

입자를 부유 상태에서 소성할 수 있는 수직로를 이용하여 2 mm 이하 크기의 경량 세골재를 제조하고 그 물리적 특성을 고찰하였다. $1200{\sim}1300^{\circ}C$에서 소성된 대부분 시편은 표면에 다량의 액상이 발달하였고 따라서 내부의 가스가 팽창하여 다공성의 중앙부와 상대적으로 치밀한 표피층이 형성되었다. 특히 압출 성형체를 파쇄시켜 얻은 부정형의 C 계열 시편은 $1300^{\circ}C$ 이상으로 소결하면 내부에 가스가 팽창하여 시편 전체가 부풀어져서 구형으로 되었다. 본 부유 수직로에서 소성된 시편의 겉보기 비중은 $0.68{\sim}1.08$ 범위로 대부분 물에 뜰 정도의 경량이었다. 제조된 경량 세골재의 흡수율은 기공율과 비례하였고, 따라서 내부 기공들이 완전 고립된 폐쇄기공은 아님을 나타내었다. 부유소성로에서 제조된 세골재는 전기 머플로에서 소성된 시편과 비슷한 물성을 나타내었으나, 전기로에서 나타나는 골재 간 융착 현상이 발생하지 않았다. 수직로에서 부유소성된 세골재의 내충격성은 자연골재보다 다소 낮았으나, 단위용적중량은 KS 규격 기준을 만족하였다.

• Carbon letters
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• 제11권1호
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• pp.1-8
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• 2010

The adsorption of Acid Blue 92 onto three low cost and ecofriendly biosorbents viz., cow dung ash, mango stone ash and parthenium leaves ash and commercial activated carbon have discussed in this work. The ash of all the mentioned bio-wastes was prepared in the muffle furnace at $500^{\circ}C$ and all the adsorbents were stored in an air thermostat. Experiments at total dye concentrations of 10~100 mg/L were carried out with a synthetic effluent prepared in the laboratory. The parameters such as pH and dye concentration were varied. Equilibrium adsorption data followed both Langmuir and Freundlich isotherms. The results indicate that cow dung ash, mango stone ash and parthenium leaves ash could be employed as low-cost alternatives to commercial activated carbon in wastewater treatment for the removal of dye.