• Title/Summary/Keyword: temperature limit

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Improving Process Capability by Applying Design and Analysis of Experiment (공정능력(工程能力) 향상(向上)을 위한 실험계량적(實驗計劃的) 연구(硏究))

  • Song, Seo-Il
    • Journal of Korean Society for Quality Management
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    • v.16 no.1
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    • pp.15-22
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    • 1988
  • This paper analysis the process capability by applying experiment design to control alcohol in soluble matter mixing process of laundry soap. The results are summarized as follows: (1) Alcohol insoluble matter shows the tendency of increasing according to the mixing temperature (A) and beating velocity (B). (2) The most suitable working condition of the mixing process is $A_2B_2$, and 95% confidence limit of alcohol insoluble matter is $22.06{\pm}0.77%$. (3) The process capability index ($C_p$) of the mixing process is improved from 0.64 to 1.68.

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Evaluation of fire resistance according to load ratio and limit temperature (하중비와 한계온도에 의한 강구조 부재의 내화성능평가법 제안)

  • Kwon, In-Kyu;Kim, Heung-Youl
    • Proceedings of the Korea Institute of Fire Science and Engineering Conference
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    • 2010.04a
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    • pp.395-399
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    • 2010
  • 강구조 부재의 내화성능평가를 위한 비재하가열시험은 강재 허용온도로 평가되고 있으나, 강재의 허용온도 설정은 H형강 부재의 최대하중로 평가되는 한계용도와 고온에서의 강소재의 허용응력도 능력으로 설정되었으므로 실지 작용되는 강구조 부재의 하중조건과 다양한 부재의 종류 등의 관점에서 허용온도의 적용은 다소 불합리한 점이 있다고 판단된다. 따라서 본 연구에서는 강구조 건축물에서의 부재에 작용하는 하중에 따른 내화성능의 차이를 보이고 이에 따른 합리적인 내화성능 평가방법을 제안하고자 한다.

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Estimation of Shelf Life Distribution of Seasoned Soybean Sprouts Using the Probability of Bacillus cereus Contamination and Growth

  • Lee, Dong-Sun;Hwang, Keum-Jin;Seo, II;Park, Jin-Pyo;Paik, Hyun-Dong
    • Food Science and Biotechnology
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    • v.15 no.5
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    • pp.773-777
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    • 2006
  • Growth of Bacillus cereus was assessed during the storage of seasoned soybean sprouts at 0,5, 10, and $15^{\circ}C$. No lag time in its growth curve was observed and thus the specific growth rate of B. cereus in the exponential growth phase was estimated for bootstrapped microbial count data. The distribution of the specific growth rate could be explained by the BetaGeneral distribution function, and temperature dependence was described by the Ratkowsky square root model. The temperature dependence of the growth could be successfully incorporated into the differential equation of microbial growth to predict the B. cereus count on the seasoned soybean sprouts under fluctuating temperature conditions. Safe shelf lives with different probabilities to reach $10^5\;CFU/g$ were presented at four different temperatures, considering the variation in initial contamination and specific growth rate by the Monte Carlo method and 2-step bootstrapping, respectively. Safe shelf lives defined as the time with a probability of less than 0.1% of reaching the critical limit, were 13.4, 5.2, 3.6, and 2.8 days at 0, 5, 10, and $15^{\circ}C$, respectively.

A Study on the Combustion Characteristics of MCFC Offgas Catalytic Combustors (MCFC 배가스용 촉매연소기 연소특성에 관한 연구)

  • Lee, Sang Min;Lee, Younhwa;Ahn, Kook Young;Park, In-Wook
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.132.1-132.1
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    • 2010
  • Anode off-gas of high temperature fuel cells such as MCFC still contain combustible components such as hydrogen, carbon monoxide and hydrocarbon. Thus, it's very important to fully burn anode off-gas and use the generated heat in order to increase system efficiency. In the present study, catalytic combustors have been applied to high temperature MCFC system so that the combustion of anode-off gas can be boosted up. Since the performance of catalytic combustor directly depends on the combustion catalyst, this study has been focused on the experimental investigation on the combustion characteristics of multiple commercial catalysts having different structures and compositions. In order to determine the design conditions of the catalytic combustor, parameters such as inlet temperature, space velocity and excess air ratio have been varied and optimized for combustor design. Results show that $H_2$ in off-gas assists $CH_4$ combustion in a way that it decreases minimum inlet temperature limit and increases maximum space velocity while keeping high fuel conversion efficiency.

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Establishment of Selection Method for Cold-Tolerant Individuals through Evaluating Tolerance of Evergreen Quercus spp. against Cold Stress

  • Park, DongJIn;Yong, Seong Hyeon;Choi, Myung Suk
    • Journal of Forest and Environmental Science
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    • v.35 no.4
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    • pp.232-239
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    • 2019
  • This study was carried out to establish an efficient selection condition for cold-tolerant individuals among evergreen Quercus spp. To select higher cold-tolerant individuals among four species of evergreen Quercus spp. (Q. acuta, Q. glauca, Q. myrsinaefoila, and Q. salicina), an-year-old seedlings of each species were exposed to low temperature in serial, and then examined for the death of cell tissue and the surface temperature was monitored. It was shown that the higher numbers of seedlings of Q. myrsinaefolia were survived than the others when those seedlings are exposed to cold stress. Thus, selection of the cold tolerant individuals was conducted on Q. myrsinaefolia seedlings. The limit low temperature condition for selecting cold-tolerant individuals was -6℃ for 24 hrs because no seedling of Q. myrsinaefolia was survived after exposed to -7℃ for 24 hours. It was shown that the leaf surface temperature of the selected individuals was higher than those of the non-selected individuals when they were exposed to cold-stress while monitoring them using thermal graphic camera. The results in this study can be used for expanding afforestation area of tree species of the warm temperate zone for preparation of climate change.

Preparation and characterization of isotropic pitch-based carbon fiber

  • Zhu, Jiadeng;Park, Sang Wook;Joh, Han-Ik;Kim, Hwan Chul;Lee, Sungho
    • Carbon letters
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    • v.14 no.2
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    • pp.94-98
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    • 2013
  • Isotropic pitch fibers were stabilized and carbonized for preparing carbon fibers. To optimize the duration and temperature during the stabilization process, a thermogravimetric analysis was conducted. Stabilized fibers were carbonized at 1000, 1500, and $2000^{\circ}C$ in a furnace under a nitrogen atmosphere. An elemental analysis confirmed that the carbon content increased with an increase in the carbonization temperature. Although short graphitic-like layers were observed with carbon fibers heat-treated at 1500 and $2000^{\circ}C$, Raman spectroscopy and X-ray diffraction revealed no significant effect of the carbonization temperature on the crystalline structure of the carbon fibers, indicating the limit of developing an ordered structure of isotropic pitch-based carbon fibers. The electrical conductivity of the carbonized fiber reached $3.9{\times}10^4$ S/m with the carbonization temperature increasing to $2000^{\circ}C$ using a four-point method.

Needle Type of Hybrid Temperature Probe for Both Diagnosis and Treatment of Musculoskeletal Pain Syndrome (근골격계 통증질환의 진단과 치료를 위한 주사바늘형 복합온도 프로브의 개발)

  • Nam, Sung-Ki;Kim, Hyung-Il;Byun, Chang-Ho;Lee, Sun-Kyu
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.4
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    • pp.359-364
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    • 2014
  • This paper describes the development of needle type probe that measures temperature and injects medicine for both diagnosis and treatment of musculoskeletal pain syndrome (MPS). The size of trigger points is from several micrometers to millimeter. Therefore, it is required to develop a medical device that is capable of not only finding the trigger points by temperature measurement, but also injecting medicine at the exact location for treatment. To challenge these difficulties, thermocouple was fabricated on the surface of a needle using metal deposition process. Special type of stainless-constantan thermocouple was achieved from the stainless body of a needle itself and deposited constantan metal film. In particular, parylene coating enables to limit the temperature sensitive area to the end of the needle tip. Fabricated needle type probe produces $3.25mV/^{\circ}C$ of thermoelectric sensitivity and compared its performance with commercial T-type thermocouple in animal muscle sample.

Measurements of Autoigniton Temperature(AIT) and Time Lag of BTX(Benzene, Toluene, Xylenes) (BTX(Benzene, Toluene, Xylenes)의 자연발화온도와 발화지연시간의 측정)

  • Ha, Dong-Myeong
    • Journal of the Korean Society of Safety
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    • v.21 no.3 s.75
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    • pp.45-52
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    • 2006
  • The AITs(autoignition temperatures) describe the minimum temperature to which a substance must be heated, without the application of a flame or spark, which will cause that substance to ignite. The AITs are often used as a factor in determining the upper temperature limit for processing operations and conditions for handling, storage and transportation, and in determining potential fire hazard from accidental contact with hot surfaces. The measurement AITs are dependent upon many factors, namely initial temperature, pressure, volume, fuel/air stoichiometry, catalyst material, concentration of vapor, time lag. Therefore, the AITs reported by different ignition conditions are sometimes significantly different. This study measured the AITs of benzene, toluene and xylene isomers from time lag using AS1M E659-78 apparatus. The experimental ignition delay times were a good agreement with the calculated ignition delay times by the proposed equations wtih a few A.A.D.(average absolute deviation). Also The experimental AITs of benzene, toluene, o-xylene, m-xylene and p-xylene were $583^{\circ}C,\;547^{\circ}C,\;480^{\circ}C,\;587^{\circ}C,\;and\;557^{\circ}C$, respectively.