• 한국기계가공학회지
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• 제21권1호
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• pp.28-33
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• 2022

The heating roller of an actual pulse output device (POD) production facility is composed of a steel roller and a rubber roller. The time to reach a specific temperature and the temperature distribution on the roller surface were analyzed and compared according to the change in the number of cartridge heaters inside the heating roller. In this analysis, a steady-state thermal analysis of a steel roller was performed for the cases of a 5-cartridge heater and 9-cartridge heater. Finite element analysis was applied with reference to the surface temperature data of the heating roller during operation and the calorific value of the cartridge heater. Using the 9-cartridge heater, faster target temperature achievement and more uniform temperature distribution were confirmed than for the 5-cartridge heater.

• Tribology and Lubricants
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• 제15권4호
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• pp.291-296
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• 1999

This paper presents the results of thermoelastic wear behaviors in ventilated disk brakes for a high-speed automotive and train using the finite element method. The computed results show that the sinusoidal distortions due to non-uniform distributions of temperature profiles may lead to thermoelastic wears on the rubbing surface. This may decrease the service life of a disk brake and produce micro-cracks, noise and squeals between two rubbing surfaces.

• 소성∙가공
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• 제15권1호
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• pp.15-20
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• 2006

The rapid thermal response (RTR) molding is a novel process developed to raise the temperature of mold surface rapidly to the polymer melt temperature prior to the injection stage and then cool rapidly to the ejection temperature. The resulting filling process is achieved inside a hot mold cavity by prohibiting formation of frozen layer so as to enable thin wall injection molding without filling difficulty. The present work covers flow simulation of thin wall injection molding using the RTR molding process. In order to take into account the effects of thermal boundary conditions of the RTR mold, coupled analysis with transient heat transfer simulation is suggested and compared with conventional isothermal analysis. The proposed coupled simulation approach based on solid elements provides reliable thin wall flow estimation for both the conventional molding and the RTR molding processes.

• The Korean Journal of Ceramics
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• 제4권4호
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• pp.345-351
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• 1998

Thermal shock resistance of $Al_2O_3$- and Fe-$Al_2TiO_5$-based Castable Refractories was studied using a central heating technique. Ring type specimens, 10mm thick and 20 and 100mm inner and outer diameters, respectively, were rapidly heated on the internal surface of the centre hole using a high power electrical heating element. The temperature field was measured experimentally and modelled using finite element analysis (FEA). The thermal stress field was also modelled using FEA. A radial notch was introduced to the ring specimens to enable calculation of the thermal stress intensity factors (SIF). A special LVDT device was incorporated in the thermal shock tester to monitor crack mouth opening displacement (COD). The thermal shock fracture initiation and crack propagation behaviour of the castable refractories were ascertained using the COD measurements and the fracture mechanics analysis data.

• 한국초전도ㆍ저온공학회논문지
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• 제25권2호
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• pp.14-18
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• 2023

Superconducting layers deposited on the metal substrate using the pulsed laser deposition process (PLD) play a crucial role in exploring new applications of superconducting wires and enhancing the performance of superconducting devices. In order to improve the superconducting property and increase the throughput of superconducting wire fabricated by pulsed laser deposition, high temperature heating device is needed that provides high temperature stability and strong durability in high oxygen partial pressure environments while minimizing performance degradation caused by surface contamination. In this study, new heating device have been developed for PLD process that deposit and growth the superconducting material continuously on substrate using reel-to-reel transportation apparatus. New heating device is designed and fabricated using iron-chromium-aluminum wire and alumina tube as a heating element and sheath materials, respectively. Heating temperature of the heater was reached over 850 ℃ under 700 mTorr of oxygen partial pressure and is kept for 5 hours. The experimental results confirm the effectiveness of the developed heating device system in maintaining a stable and consistent temperature in PLD. These research findings make significant contributions to the exploration of new applications for superconducting materials and the enhancement of superconducting device performance.

• 수산해양기술연구
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• 제53권3호
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• pp.302-307
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• 2017

An electric steam boiler equipped with a condensate recovery system, which stores the condensate generated after using steam in steam washers, steam cookers, steam irons, and steam cleaners in a condensate tank and supplies compressed air to the condensate tank so that the condensate is recovered to the boiler by the pressure of the compressed air, was studied. In the results of this study, the heat energy balance between the quantity of the heat generated by the non-metallic surface heating element and the quantity of the heat absorbed by the water was good in a range of ${\pm}5%$. In addition, the heat transfer rate increased in proportion to the electric power of the surface heating element heater, the waste heat energy was normally recovered by the recovery of the condensate of the steam boiler equipped with the high compression waste heat recovery system, and the recovery rate of the waste heat exhibited 23%.

• Journal of Mechanical Science and Technology
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• 제14권3호
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• pp.298-305
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• 2000

The functionally graded material (FGM) is the new concept for a heat resisting material. FGM consists of ceramics on one side and metal on the other. A composition and microstructure of an intermediate layer change continuously from ceramics to metal at the micron level. This study is carried out to analyze the thermal shock characteristics of functionally graded PSZ/ metal composites. Heat-resistant property was evaluated by gas burner heating test using $C_2H_2/O_2$ combustion flame. The ceramic surface was heated with burner flame and the bottom surface cooled with water flow. Also, the composition profile and the thickness of the graded layer were varied to study the thermo mechanical response. Furthermore, this study carried out the thermal stress analysis to investigate the thermal characteristics by the finite element method. Acoustic emission (AE) monitoring was performed to detect the microfracture process in a thermal shock test.

• 한국식품영양학회지
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• 제17권1호
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• pp.32-40
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• 2004

간장으로 채워진 실린더 형태의 장조림 제품의 가열살균 시 온도변화를 유한요소분석법(finite element method)을 이용하여 예측하기 위하여 상업적 NISA (Numerical Integrated Elements for System Analysis, EMRC, USA)프로그램을 이용하여 실시하였다. 장조림 식품에서의 열전달은 냉점이 기하학적 중심에 위치하지 않고 y축으로 26.9 mm 뒤쪽에 위치하였다. 이는 간장소스의 비열이 장조림보다 20% 이상 큰 값이기 때문으로, 사용된 재료의 열전달계수에 의해서 냉점의 위치가 다르게 나타났다. 장조림 식품의 가열살균 시 열전달계수의 영향을 검토하기 위하여 온도와 치사율 오차를 종속변수로 하여 간장소스의 열전도계수, 장조림의 열전도계수, 열전달계수를 독립변수로 한 반응표면분석법을 행한 결과 장조림의 열전도계수가 p<0.01로 매우 높은 상관관계를 보이며, 치사율 오차를 최소로 하는 최적화값을 얻을 수 있었다.

• Corrosion Science and Technology
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• 제23권4호
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• pp.315-323
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• 2024

This work examined pitting corrosion failure of a copper heat-return pipe used in a district heating system. The copper pipe was corroded with a 48% reduction in thickness due to localized corrosion on the inner surface exposed to heating water of 20 ~ 40 ℃. Fe and Si elements as corrosion products were found around pits. Cl element was also observed, which accelerated oxidation of copper inside pits. Cu₂O deposits on the pit's bottom surface decreased the pH inside the pit. X-ray diffraction analysis revealed hematite, cuprite, malachite and brochantite as corrosion products. Chemical analysis demonstrated that Fe and Si elements did not exist in the copper, supply water, or heating water, indicating that Fe and Si species might have entered into the pipe from the exterior. These results indicated that pits were initiated due to ion concentration gradient near Fe and Si species. Moreover, the interior of pits had lower pH due to Cl^- concentration and Cu₂O reactions, which accelerated the pit's growth and led to formation of pinholes. Additionally, we confirmed that the type of pitting corrosion was a complex combination of types I and II based on the HCO₃^-/SO₄^2- ratio, pH, temperature, and corrosion products.

• Composites Research
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• 제26권1호
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• pp.72-78
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• 2013

불연속 탄소섬유-에폭시 복합재의 저항발열 특성에 관한 연구를 수행하였다. 1, 3, 5 wt.% 불연속 탄소섬유가 함유된 복합재 시험편을 초음파 처리와 캐스트 몰딩(cast molding)을 이용하여 제조하였다. 시편에 DC 전류 인가시 발생되는 저항열에 의한 시편의 표면온도 변화를 적외선 카메라를 이용하여 측정하였다. 발열온도를 예측하기 위해서 유한요소해석을 수행하였는데, 실측된 온도와 부합함을 확인하였다. 탄소섬유의 함량과 인가전압이 증가할수록 발열저항에 의해서 발생된 열은 증가함을 확인하였다. 복합재 내에서 균일한 온도분포를 얻기 위해서는 탄소섬유의 분산상태가 중요하며, 대기온과 습도 등 실험환경이 발열온도에 영향을 미치는 것으로 나타났다.