• Title, Summary, Keyword: Thermal process

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Residual Stress Measurement of Sand Casting by ESPI Device and Thermal Stress Analysis (ESPI 장비를 활용한 사형 주조품의 잔류응력 측정 및 주조 열응력 해석)

  • Kwak, Si-Young;Nam, Jeong-Ho
    • Journal of Korea Foundry Society
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    • v.40 no.1
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    • pp.1-6
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    • 2020
  • Many studies involving a thermal stress analysis using computational methods have been conducted, though there have been relatively few experimental attempts to investigate thermal stress phenomena. Casting products undergo thermal stress variations during the casting process as the temperature drops from the melting temperature to room temperature, with gradient cooling also occurring from the surface to the core. It is difficult to examine thermal stress states continuously during the casting process. Therefore, only the final states of thermal stress and deformations can be detemined. In this study, specimens sensitive to thermal stress, were made by a casting process. After which the residual stress levels in the specimens were measured by a hole drilling method with Electron Speckle-Interferometry technique. Subsequently, we examined the thermal stresses in terms of deformation during the casting process by means of a numerical analysis. Finally, we compared the experimental and numerical analysis results. It was found that the numerical thermal stress analysis is an effective means of understanding the stress generation mechanism in casting products during the casting process.

Assessment of Thermal Hazard on Esterification Process in Manufacture of Concrete Mixture Agents by Multimax Reactor System (Multimax Reactor System을 이용한 시멘트 혼화제 제조시 에스테르화공정의 열적 위험성 평가)

  • Han, In-Soo;Lee, Keun-Won;Pyo, Don-Young
    • Journal of the Korean Society of Safety
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    • v.24 no.5
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    • pp.13-20
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    • 2009
  • The risk assessment of thermal hazard to identify chemical or process hazard during early process developments have been considered. The early identification of thermal hazards associated with a process, such as rapid heats of reaction, exothermic decompositions, and the potential for thermal runaways before any large scale operations are undertaken. This paper presents to evaluate the safe operating parameters/envelope for exist plant operations. The assessment of thermal hazard with operating conditions such as amount of process materials, inhibitor, and catalyst on esterification process in manufacture of concrete mixture agents are described. The experiments were performed by a sort of calorimetry with the Multimax reactor system as a screening tool. The aim of the study was to evaluate the thermal risk of process material and mixture in terms of safety security to be practical applications in esterification process. It suggested that we should provide the thermal hazard of reaction materials to present safe operating conditions with cause of accident through this study.

Use of Nisin as an Aid in Reduction of Thermal Process of Bottled Sikhae (Rice Beverage)

  • Yoo, Jin-Young;Kwon, Dong-Jin;Park, Jong-Hyun;Koo, Young-Jo
    • Journal of Microbiology and Biotechnology
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    • v.4 no.2
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    • pp.141-145
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    • 1994
  • Conventional commercial thermal process for preparing Sikhae (Rice beverage) in a hermetically sealed container was evaluated to solve the nutritional deterioration and organoleptic inferiority problem caused by severe heat treatment. A milder thermal process with an aid of Nisin, a GRAS-grade, selectively germicidal compound, was introduced to destroy the putrefactive microorganisms. In this experiment, hot-filling method with Nisin, and thermal processing (at 110$^{\circ}C$ for 15 minutes with Nisin, at 121$^{\circ}C$ for 25 minutes without Nisin) were compared. The quality of Sikhae could be enhanced and over 90% of the thermal process could be conserved by this process in terms of sterilizing value without quality deterioration when processing the bottled Sikhae at 110$^{\circ}$ for 15 minutes $\{(F^{10}{_{121})_{process}=1.54\}$.

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An Analytical Study on the Thermal-Structure Stability Evaluation of Mill-Turn Spindle with Curvic Coupling (커빅 커플링을 적용한 밀-턴 스핀들의 열-구조 안정성 평가에 관한 해석적 연구)

  • Lee, Choon-Man;Jeong, Ho-In
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.1
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    • pp.100-107
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    • 2020
  • As demand for high value-added products with hard materials increases, the line center is used for producing high value-added products in many industries such as aerospace, automobile fields. The line center is a key device for smart factory automation that can improve the production efficiency and the productivity. Therefore, the development of a mill-turn line center is necessary to produce high value-added products with complex shapes flexibly. In the mill-turn process, a milling process and a turning process are combined. In particular, the turning process needs to increase the rigidity of the spindle. The purpose of this study is to analyze the thermal-structural stability through thermo-structural coupled analysis for a mill-turn spindle with a curvic coupling. The maximum temperature and thermal stability of the spindle were analyzed by thermal distribution. In addition, the thermal deformation and thermal-structural stability of the spindle were analyzed through thermo-structural coupled analysis.

An Evaluation of Thermal Stability of Raw Materials in the Vinyl Acetate Polymerization Process (비닐아세테이트 중합공정에서 원료물질의 열적 안정성 평가)

  • Lee, Keun-Won;Han, In-Soo;Lee, Jung-Suk
    • Journal of the Korean Society of Safety
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    • v.25 no.3
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    • pp.61-65
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    • 2010
  • Most of the chemical reactions performed in the chemical industry are exothermic, meaning that thermal energy is released during the reaction. It is also important to understand the thermal hazards such as thermal stabilities and runaway reactions, which are governed by thermodynamics and reaction kinetics of the mixed materials. The paper was described the evaluation of thermal behavior caused by an exothermic batch process in manufacture of the vinyl acetate resin. The aim of the study was to evaluate the thermal stabilities of raw materials with operating conditions such as a reaction inhibitor, heating rate, reaction atmosphere and the mount of methanol charged in the vinyl acetate polymerization process. The experiments were performed in the differential scanning calorimeter(DSC), C 80 calorimeter, and thermal screening unit($TS^u$). It was suggested that we should provide the thermal characteristics for raw materials to present safe precautions with operating conditions in the vinyl acetate polymerization process.

Prediction of thermal shock failure of glass during PDP manufacturing process (PDP 제조 공정시 유리의 열충격 파손 예측)

  • 김재현;최병익;이학주
    • Journal of the Korean Society for Precision Engineering
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    • v.21 no.2
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    • pp.122-129
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    • 2004
  • There is an increasing need for large flat panel display devices. PDP (Plasma Display Panel) is one of the most promising candidates for this need. Thermal shock failure of PDP glass during manufacturing process is a critical issue in PDP industry since it is closely related to the product yield and the production speed. In this study, thermal shock resistance of PDP glass is measured by water quenching test and an analysis scheme is described for estimating transient temperature and stress distributions during thermal shock. Based on the experimental data and the analysis results, a simple procedure for predicting the thermal shock failure of PDP glass is proposed. The fast cooling process for heated glass plates can accelerate the speed of PDP production, but often leads to thermal shock failure of the glass plates. Therefore, a design guideline for preventing the failure is presented from a viewpoint of high speed PDP manufacturing process. This design guideline can be used for PDP process design and thermal -shock failure prevention.

Numerical Analysis on the Thermal Choking Process In a Model SCRamjet Engine (모델 스크림제트 연소기내의 열질식과정 수치해석)

  • Moon, G.W.;Choi, J.Y.;Jeung, I.S.
    • 한국연소학회:학술대회논문집
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    • pp.76-84
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    • 2000
  • A numerical study was conducted for the investigation of thermal choking process in a model scramjet engine based on the experimental results at the Australian National University. The results of numerical simulation showed that thermal choking process could be related to the interaction between hypersonic flow and fuel-air mixing process. Especially, we could make sure that turbulent mixing was most important parameter to the thermal choking process.

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Evaluation of Thermal Stability in Neutralization Process of Pigment Plant (안료제조시 중화공정의 열안정성 평가)

  • Lee, Keun-Won;Han, In-Soo;Park, Sang-Hyun
    • Journal of the Korean Society of Safety
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    • v.22 no.4
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    • pp.43-50
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    • 2007
  • Lack of understanding of the process chemistry and thermodynamics are the major reasons that can is lead to thermal runaway reaction in the chemical reaction process. The evaluation of reaction factors and thermal behavior in neutralization process of pigment plant are described in this paper. The experiments were performed in the C 80 calorimeter, and Thermal Screening Unit($TS^{u}$). The aim of the study was to evaluate the results of thermal stability in terms of safety reliability to be practical applications. It suggested that we be proposed safe operating conditions and securities for accident prevention through this study.

Electrical Property Evaluation of Printed Copper Nano-Ink Annealed with Infrared-Lamp Rapid Thermal Process (적외선 램프를 이용하여 소결한 구리 나노잉크의 전기적 특성 평가에 관한 연구)

  • Han, Hyun-Suk;Kim, Changkyu;Yang, Seung-Jin;Kim, Yoon-Hyun
    • Korean Journal of Materials Research
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    • v.26 no.4
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    • pp.216-221
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    • 2016
  • A sintering process for copper based films using a rapid thermal process with infrared lamps is proposed to improve the electrical properties. Compared with films produced by conventional thermal sintering, the microstructure of the copper based films contained fewer internal and interfacial pores and larger grains after the rapid thermal process. This high-density microstructure is due to the high heating rate, which causes the abrupt decomposition of the organic shell at higher temperatures than is the case for the low heating rate; the high heating rate also induces densification of the copper based films. In order to confirm the effect of the rapid thermal process on copper nanoink, copper based films were prepared under varying of conditions such as the sintering temperature, time, and heating rate. As a result, the resistivity of the copper based films showed no significant changes at high temperature ($300^{\circ}C$) according to the sintering conditions. On the other hand, at low temperatures, the resistivity of the copper based films depended on the heating rate of the rapid thermal process.

Fabrication Process and Characterization of High Thermal Conductivity-Low CTE SiCp/Al Metal Matrix Composites by Pressure Infiltration Casting Process (가압함침법에 의한 고열전도도-저열팽창계수 SiCp/Al 금속복합재료의 제조공정 및 특성평가)

  • 이효수;홍순형
    • Proceedings of the Korean Society For Composite Materials Conference
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    • pp.83-87
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    • 1999
  • The fabrication process and thermal properties of 50~71vol% SiCp/Al metal matrix composites (MMCs) were investigated. The 50~71vol% SiCp/Al MMCs fabricated by pressure infiltration casting process showed that thermal conductivities were 118~170W/mK and coefficient of thermal expansion (CTE) were 9.5~$6.5{\times}10^{-6}/K$. Specially, the thermal conductivity and CTE of 71vol%SiCp/Al MMCs were 115~156W/mK and 6~$7{\times}10^{-6}/K$. respectively, which showed a improved themal properties than the conventional electronic packaging materials such as ceramics and metals.

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