• Title, Summary, Keyword: heat treatment

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A Study on Slide Way Deformation from High Frequency Heat Treatment by Finite Element Method (유한요소법을 이용한 고주파 열처리시 안내면 변형에 관한 연구)

  • 홍성오;조규재
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.11 no.3
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    • pp.57-64
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    • 2002
  • Finite element program(ANSYS) estimated thermal deformation quantity in high frequency heat treatment process of a machine tool fred drive system slideway and apply deformation quantity in roughing process. Having processed the heat treatment minimizing methods of the quantity of deformation heat treatment process. Having done heat treatment with high frequency after taper processing with considering the existed heat treatment generating the quantity of deformation, existed quantity of deformation can be reduced down to 80%, consequently productivity and material saving can be achieved. When high frequency heat treatment finite element method estimated deformation quantity at difference temperature and time, it is progress at cost don and saved time.

A Study on Mechanical Properties and Microstructure of Local-Hardening Heat-Treated Automotive Panel (국부 경화 열처리된 차체 부품의 기계적 성질과 미세조직에 관한 연구)

  • Lee, Jae Ho;Jeong, Woo Chang
    • Journal of the Korean Society for Heat Treatment
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    • v.23 no.6
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    • pp.301-308
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    • 2010
  • A steel with chemical composition, 0.22% C, 0.25% Si, 1.26% Mn, 0.22% Cr, 0.04% Ti, 0.0042% B, and a microstructure of ferrite and spheroidized cementite has been press-formed to automotive center pillar followed by local-hardening heat-treatment. Hardness, tensile properties, fractography, microstructure and surface roughness of local-hardening heat-treated automotive center pillar have been examined. The directly heated and quenched area had fully martensitic structure with Vickers hardenss in the range of 500 to 510. The heat affected area close to the directly heated area showed dual-phase structure of ferrite and martensite. The width of the heat-treated and heat-affected areas after the local-hardening heat treatment was ranging from 32 mm to 50 mm. The surface of the local-hardening heat-treated center pillar revealed some temper color as a consequence of the oxidation during the heat treatment, but the surface roughness was not affected by the local-hardening heat treatment.

Studies on Heat Sensitivity of Egg Albumen III. Effects of Egg Albumen Concentration and Addition of Sugars on Heat Sensitivity of Egg Albumen (난백의 열감수성에 관한 연구 III. 난백의 농도와 당류의 첨가가 난백의 열감수성에 미치는 영향)

  • 유익종;김기성;송계원
    • Korean Journal of Poultry Science
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    • v.16 no.1
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    • pp.23-28
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    • 1989
  • This study was undertaken to find out the effect of eeg albumen concentration and addition of sugars on the functional properties of egg albumen before and after heat treatment at $60^{\circ}C$ for 5 minutes. The turbidity was decreased until 8.3% protein concentration but increased as diluted and decreased again below 3.32% protein concentration before and after the heat treatment. The foaming power was peak at 8.3% protein concentration but decreased as diluted before and after the heat treatment. The foam stability was decreased as diluted before and after the heat treatment. The turbidity was not changed by addition of sucrose before the heat treatment and decreased after the heat treatment. The foaming power was decreased by addition of over 5% sucrose before the heat treatment and decreased by addition of over 2.5% sucrose after the heat treatment . The foam stability was increased by addition of over 5% sucrose before the heat treatment and increased by addition of sucrose after the heat treatment. The turbidity was increased by addition of glucose before the heat treatment and not changed after the heat treatment. The foaming power was decreased by the addition of glucose before the heat treatment and decreased by the addition of over 5% glucose after the heat treatment. The foam stability was decreased by the addition of glucose before and after the heat treatment.

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Protective Role of Light in Heat-Induced Inhibition of Photosynthesis in Isolated Chloroplasts

  • Jun, Sung-Soo;Kim, Chang-Hoon;Hong, Young-Nam
    • Journal of Photoscience
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    • v.5 no.4
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    • pp.157-162
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    • 1998
  • The effect of heat treatment in the light on the subsequent CO2 fixation was studied with isolated spinach chloroplasts to define the role of light during heat stress. The degree of inhibition in CO2 fixation after heat treatment at 35$^{\circ}C$ under full light intensity (600W/$m^2$) was same as that in the dark. However, heat treatment of isolated chloroplasts in the light manifested thylakoidal damage, which did not occur in the dark. Under weak light (10~30 W/$m^2$ ) where no thylakoidal damage occurred, the inhibition was substantially alleviated , showing protective effect of light . The inhibition caused by heat treatment in the dark or light is prevented by the addition of a few combined compounds to the medium prior to treatment. Fructose-1-6- bisphosphate(with aldolase)and ribose-5-phosphate, known to be effective combined with oxaloacetate in preventing inhibition after heat treatment in the dark were equally effective in the light even without oxaloacetate. Addition of sugar phosphate reduced the Mehler reaction, which may occur in fast rae under high light. However, the addition of bicarbnate and catalase that would remove Mehler reaction did not provide any protection, indicating that protective role of sugar phosphate is elsewhere. Furghermore, in whole plants rapid recovery from heat stress was observed in the light. The apparently lesser or equal inhibition in spite of additional thylakoidal damage under heat stres in the light and less requirement for the protection against heat treatment suggest that the inhibitory effect of heat stress is alleviated by light treatment.

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A Study on SCr420HB Helical Gear Deformative Simulation by Heat Treatment Quenching Method (열처리 냉각방식 변화에 따른 SCr420HB 헬리컬 기어 시뮬레이션 적용에 관한 연구)

  • Byun, J.H.;Byun, S.D.;Yi, C.H.
    • Journal of the Korean Society for Heat Treatment
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    • v.28 no.1
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    • pp.24-31
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    • 2015
  • In this study, a simulation was used to derive an optimal process of heat treatment with carburizing, and compared the derived result with SCr420HB helical gear in heat treatment with carburized quenching process about a change of the quenching method. The optimal carburizing process time is derived by the simulation with the theoretical time. The process has been performed by oil quenching and salt quenching method. Through the comparison of the results from the simulation(Hardness, effective case depth hardened by carburizing treatment and deformation) and the actual process, analyzed the error value of each quenching. And it verified the applicability of the simulation.

Effects of Heat Treatment on the Nutritional Quality of Milk. IV. Effects of Heat Treatment on the Physical and Nutritional Properties of Milk Protein (우유의 열처리가 우유품질과 영양가에 미치는 영향: IV. 우유의 열처리가 우유단백질의 이화학적 성질과 영양에 미치는 영향)

  • Jung, Jong-Wook;Jung, Jiyoon;Mim, Tae Sun;Oh, Sejong
    • Journal of Dairy Science and Biotechnology
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    • v.35 no.4
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    • pp.270-285
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    • 2017
  • Among milk proteins, caseins are not subjected to chemical changes during heat treatment of milk; however, whey proteins are partially denatured following heat treatment. The degree of whey protein denaturation by heat treatment is decreased in the order of high temperature short time (HTST) > low temperature long time (LTLT) > direct-ultra-high temperature (UHT) > indirect-UHT. As a result of heat treatment, several changes, including variations in milk nitrogen, interactions between beta-lactoglobulin and k-casein, variations in calcium sulfate and casein micelle size, and delay of milk coagulation by chymosin action, were observed. Lysine, an important essential amino acid found in milk, was partially inactivated during heat treatment. Therefore, the available amount of lysine decreased slightly (1~4% decrease) after heat treatment, However, the influence of heat treatment on the nutritional value of milk was negligible. Nutritional value and nitrogen balance did not differ significantly between UHT and LTLT in milk. In conclusion, our results showed that heat treatment of milk did not alter protein quality. Whey proteins denatured to a limited extent during the heat treatment process, and the nutritional value and protein quality were unaffected by heat treatment.

Effect of Heat Treatments on Welding Residual Stresses of 18% Ni Maraging Steel (18% Ni 마레이징강의 용접 잔류 응력에 미치는 열처리의 영향)

  • 배강열;나석주;김원훈
    • Journal of Welding and Joining
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    • v.11 no.2
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    • pp.53-61
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    • 1993
  • One of the most interesting and promising steel groups considered for the rocket motor case, aircraft and aerospace component is the maraging(martensitic plus aging) nickel steel, developed by International Nickel Company in 1960. This material attains a very high strength with good fracture toughness by simple heat treatments which do not involve a quenching. Full strength can be obtained by "maraging" at 480.deg. for 3 hours for the 18% Ni maraging steel. The effect of heat treatments was considered on the residual stress field of 18% Ni maraging steel weldments. In experiments, various heat treatments such as stress relieve heat treatment, aging and solution heat treatment were carried out of the GTA weldments and the residual stresses were measured by using the hole drilling method. Whereas the conventional pattern of residual stress shows the stresses to be maximum along the weld centerline with tensile stress extending into the heat affected zone, the pattern in maraging steels shows the centerline stress to be compressive. After welding, a series of aging, solution heat treatment and solution heat treatment plus aging treatment were carried out and the residual stresses were measured to reveal that these heat treatments almost completely remove the welding residual stresses.

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Dry-Heat Treatment Process for Enhancing Viral Safety of an Antihemophilic Factor VIII Concentrate Prepared from Human Plasma

  • Kim, In-Seop;Choi, Yong-Woon;Kang, Yong;Sung, Hark-Mo;Shin, Jeong-Sup
    • Journal of Microbiology and Biotechnology
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    • v.18 no.5
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    • pp.997-1003
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    • 2008
  • Viral safety is a prerequisite for manufacturing clinical antihemophilic factor VIII concentrates from human plasma. With particular regard to the hepatitis A virus (HAV), a terminal dry-heat treatment ($100^{\circ}C$ for 30 min) process, following lyophilization, was developed to improve the virus safety of a solvent/detergent-treated antihemophilic factor VIII concentrate. The loss of factor VIII activity during dry-heat treatment was of about 5%. No substantial changes were observed in the physical and biochemical characteristics of the dry-heat-treated factor VIII compared with those of the factor VIII before dry-heat treatment. The dry-heat-treated factor VIII was stable for up to 24 months at $4^{\circ}C$. The dry-heat treatment after lyophilization was an effective process for inactivating viruses. The HAV, murine encephalomyocarditis virus (EMCV), and human immunodeficiency virus (HIV) were completely inactivated to below detectable levels within 10 min of the dry-heat treatment. Bovine herpes virus (BHV) and bovine viral diarrhea virus (BVDV) were potentially sensitive to the treatment. However porcine parvovirus (PPV) was slightly resistant to the treatment. The log reduction factors achieved during lyophilization and dry-heat treatment were ${\geq}5.55$ for HAV, ${\geq}5.87$ for EMCV, ${\geq}5.15$ for HIV, 6.13 for BHV, 4.46 for BVDV, and 1.90 for PPV. These results indicate that dry-heat treatment improves the virus safety of factor VIII concentrates, without destroying the activity. Moreover, the treatment represents an effective measure for the inactivation of non-lipid-enveloped viruses, in particular HAV, which is resistant to solvent/detergent treatment.