• International journal of advanced smart convergence
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• 제11권4호
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• pp.28-40
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• 2022

Although precise temperature control in the heat treatment process is a key factor in process reliability, there are many cases where there is no separate heat source control optimization system in the field. To solve this problem, the program monitors the temperature data according to the heat source change through sensor communication in a recursive method based on multiple variables that affect the process, and the target heat source value and the actual heat treatment heat source to match the internal air temperature and material temperature. A control optimization system was constructed. Through this study, the error rate between the target temperature and the atmosphere (material surface) temperature of around 10.7% with the existing heat source control method was improved to an improved result of around 0.1% using a process optimization algorithm and system.

• 마이크로전자및패키징학회지
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• 제23권2호
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• pp.57-63
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• 2016

We developed a flexible and micro-thick electromagnetic interference (EMI) shielding nanofabric layer that also functions as a water resisting and heat sinking material. Electrospinning followed by a simple heat treatment process was carried on to produce the EMI-shielding Ni/C hybrid nanofibers. The ambient oxygen partial pressure ($pO_2$ = 0.1, 0.7, 1.3 Torr) applied during the heat treatment was varied in order to optimize the effectiveness of EMI-shielding by modifying the size and crystallinity of the magnetic Ni nanoparticles distributed throughout the C nanofibers. Permittivity and permeability of the nanofibers under the electromagnetic (EM) wave frequency range of 300 MHz~1 GHz were measured, which implied the EMI-shielding effectiveness (SE) optimization at $pO_2$ = 0.7 Torr during the heat treatment. The materials' heat diffusivity for both in-plane direction and vertical direction was measured to confirm the anisotropic thermal diffusivity that can effectively deliver and sink the local heat produced during device operations. Also, the nanofibers were aged at room temperature in oxygen ambient for water resisting function.

• 열처리공학회지
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• 제32권2호
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• pp.68-73
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• 2019

${\alpha}$-titanium alloy has a relatively low heat treatment characteristic and it is mainly subjected to heat treatment for residual stress, recovery or dynamic recrystallization. In this study, commercially pure titanium hollow castings was fabricated by gravity casting. Heat treatments were carried out at $750^{\circ}C$, $850^{\circ}C$ and $950^{\circ}C$ to investigate the effect of post-heat treatment on microstructure and mechanical properties. Beta-transus temperature ($T_{\beta}$) was about $913^{\circ}C$, and equiaxed microstructure was shown at temperature below $T_{\beta}$ and lath-type microstructure at temperature above $T_{\beta}$. Microstructure and mechanical properties did not show any significant difference in the direction of solidification for titanium hollow billet, so it can be seen that it was a well-made material for extrusion process. The optimum heat treatment condition of hollow billet castings for the seamless tube production was $850^{\circ}C$, 4 hr, FC, indicating a combination of equiaxed microstructure and appropriate mechanical properties.

• Carbon letters
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• 제14권2호
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• pp.110-116
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• 2013

This study investigated a developed process for producing a composite bipolar plate having excellent conductivity by using coal tar pitch and phenol resin as binders. We used a pressing method to prepare a compact of graphite powder mixed with binders. Resistivity of the impregnated compact was observed as heat treatment temperature was increased. It was observed that pore sizes of the GCTP samples increased as the heat treatment temperature increased. There was not a great difference between the flexural strengths of GCTP-IM and CPR-IM as the heat treatment temperature was increased. The resistivity of GPR700-IM, heat treated at $700^{\circ}C$ using phenolic resin as a binder, was $4829{\mu}{\Omega}{\cdot}cm$ which was best value in this study. In addition, it is expected that with the appropriate selection of carbon powder and further optimization of process we can produce a composite bipolar plate which has excellent properties.

• Journal of Microbiology and Biotechnology
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• 제31권4호
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• pp.570-583
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• 2021

Pyrococcus furiosus α-amylase can hydrolyze α-1,4 linkages in starch and related carbohydrates under hyperthermophilic condition (~ 100℃), showing great potential in a wide range of industrial applications, while its relatively low productivity from heterologous hosts has limited the industrial applications. Bacillus subtilis, a gram-positive bacterium, has been widely used in industrial production for its non-pathogenic and powerful secretory characteristics. This study was conducted to increase production of P. furiosus α-amylase in B. subtilis through three strategies. Initial experiments showed that co-expression of P. furiosus molecular chaperone peptidyl-prolyl cis-trans isomerase through genomic integration mode, using a CRISPR/Cas9 system, increased soluble amylase production. Therefore, considering that native P. furiosus α-amylase is produced within a hyperthermophilic environment and is highly thermostable, heat treatment of intact culture at 90℃ for 15 min was performed, thereby greatly increasing soluble amylase production. After optimization of the culture conditions (nitrogen source, carbon source, metal ion, temperature and pH), experiments in a 3-L fermenter yielded a soluble activity of 3,806.7 U/ml, which was 3.3- and 28.2-fold those of a control without heat treatment (1,155.1 U/ml) and an empty expression vector control (135.1 U/ml), respectively. This represents the highest P. furiosus α-amylase production reported to date and should promote innovation in the starch liquefaction process and related industrial productions. Meanwhile, heat treatment, which may promote folding of aggregated P. furiosus α-amylase into a soluble, active form through the transfer of kinetic energy, may be of general benefit when producing proteins from thermophilic archaea.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.224-231
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• 2015

Purpose: Corn is a major commercial crop targeted for genetic modification owing to its high consumer demand as a foodstuff for humans and livestock, as well as its other industrial applications. However, the safety of genetically modified (GM) crops is controversial. Indeed, several countries have banned the importation of GM seeds that can germinate. Therefore, development of effective, convenient, and nondestructive methods to inhibit seed germination is required. Methods: This study aimed to examine the efficacy of microwave heat treatment for inhibition of germination of corn kernels and for optimization of power and exposure time required for effective aging treatment. Artificial inhibition was induced in corn kernels using microwave heat treatment. Seven power levels were examined (400, 500, 600, 700, 800, 900, and 1000 W) at each of the four exposure times (0.5, 1.0, 1.5, and 2.0 min). Results: Corn kernels could be aged effectively after heating for 0.5~1.0 min at powers greater than 800 W, with increasing efficacy observed at higher powers. Further analysis showed that the most effective inhibition of germination was observed at 1000 W for 40 s. This setting did not cause any physical damage to the corn kernels. Conclusions: Optimal inhibition of corn kernel germination was achieved using higher power for shorter times, which may be useful for industrial corn seed treatment.

• Journal of Ginseng Research
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• 제39권4호
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• pp.304-313
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• 2015

Background: Ginsenoside Rg3 is a promising anticancer agent. It is usually produced by heat treatment of ginseng, in which ginsenoside Rb1 is the major ginsenoside. A kinetic study was conducted to optimize ginsenoside Rg3 production by the heat treatment of ginsenoside Rb1. Methods: Ginsenoside Rb1 was heated using an isothermal machine at $80^{\circ}C$ and $100^{\circ}C$ and analyzed using HPLC. The kinetic parameters were calculated from the experimental results. The activation energy was estimated and used to simulate the process. The optimized parameters of ginsenoside Rg3 production are suggested based on the simulation. Results: The rate constants were $0.013h^{-1}$ and $0.073h^{-1}$ for the degradation of ginsenosides Rb1 and Rg3 at $80^{\circ}C$, respectively. The corresponding rate constants at $100^{\circ}C$ were $0.045h^{-1}$ and $0.155h^{-1}$. The estimated activation energies of degradation of ginsenosides Rb1 and Rg3 were 69.2 kJ/mol and 40.9 kJ/mol, respectively. The rate constants at different temperatures were evaluated using the estimated activation energies, and the kinetic profiles of ginsenosides Rb1 and Rg3 at each temperature were simulated based on the proposed kinetic model of consecutive reaction. The optimum strategies for producing ginsenoside Rg3 from ginsenoside Rb1 are suggested based on the simulation. With increased temperature, a high concentration of ginsenoside Rg3 is formed rapidly. However, the concentration decreases quickly after the reaching the maximal concentration value. Conclusion: The optimum temperature for producing ginsenoside Rg3 should be the highest temperature technically feasible below $180^{\circ}C$, in consideration of the cooling time. The optimum reaction time for heat treatment is 30 min.

• 열처리공학회지
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• 제30권6호
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• pp.279-284
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• 2017

Mechanical properties of titanium alloy can be improved by controlling microstructure through heat treatment. In this study, Ti-3Al-8V-6Cr-4Mo-4Zr metastable beta titanium alloy, was controlled for excellent mechanical property and sound formability through various high temperature heat treatment and aging conditions and the optimum heat treatment conditions were determined. The specimens were heat-treated at $950^{\circ}C$, followed by various aging treatments from $430^{\circ}C$ to $500^{\circ}C$ for 1 to 24 h. As aging temperature and holding time increased, hardness increased by ${\beta}^{\prime}$ phase formation and precipitation of secondary ${\alpha}$ phase in ${\beta}$ matrix. However, the optimum aging temperature and holding time for mechanical properties were at $450{\sim}470^{\circ}C$ for 8~16 hr. Hardness values of the specimen aged at $450^{\circ}C$ for 8 h were found to be the highest. These results can be effectively applied to fabrication of spring with better formability and mechanical property.

• Current Research on Agriculture and Life Sciences
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• 제31권1호
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• pp.25-29
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• 2013

As a specialty oil, furan fatty acids have gained special attentions since they are known to play important roles in biological systems including human. Although several studies reported chemical synthesis of furan fatty acids, their synthesis consisted of complicated chemical multistep with chemical catalysts. Recently, a simple one-step heat treatment method was developed to produce a novel furan fatty acid, 7,10-epoxy-octadeca-7,9-dienoic acid (7,10-EODA) from a dihydroxyl fatty acid 7,10-dihydroxy-8(E)-octadecenoic acid (DOD). In this report we studied about optimization of environmental conditions for the maximum production of 7,10-EODA from DOD by heat treatment. Production of 7,10-EODA was maximized at over $85^{\circ}C$ for at least over 48 hour in hexane. Solvent volume for maximum production should be over 300 mL per 10 mg DOD.

• 대한의용생체공학회:의공학회지
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• 제19권4호
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• pp.333-339
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• 1998

본 연구에서는 혈관폐색을 위한 색전코일의 열처리 제조공정 조건을 연구하였다. 2.92mm의 알루미나 심재에 1차코일을 감은 후 475$^{\circ}C$와 600$^{\circ}C$에서 열처리하여 2차코일을 제조하였으며, 열처리 시간에 따른 2차코일의 피치간격, 내경 및 형상복원성을 평가하였다. 2차코일의 피치간격은 475$^{\circ}C$와 600$^{\circ}C$에서 각각 잠복기를 가진 후 열처리 시간이 증가함에 따라 증가하였다. 2차코일의 내경은 열처리 시간이 증가함에 딸 연속적으로 감소하였다. 이 원인은 열처리 초기에 회복에 의하여 재료의 내부에너지가 감소되면서 2차코일의 피치간격과 내경이 감소되나, 열처리 시간이 증가됨에 따라 텅스텐 표면의 산화물이 형성되면서 탄성이 증가되기 때문에 피치간격이 증가하는 것으로 분석되었다. 2차코일의 형상복원성은 텅스텐코일의 표면에 형성된 텅스텐 산화물이 탄성을 증가시킴으로 인해 열처리 시간이 증가함에 따라 연속적으로 증가하였다. 열처리 온도 영향을 비교하면 산화물형성 속도가 빠른 600$^{\circ}C$가 475$^{\circ}C$보다 더 우수한 형상복원성을 나타내었다. 텅스텐 색전코일의 제조공정 연구결과 2차코일의 피치간격, 내경 및 형상 복원성을 최적화하기 위해서는 600$^{\circ}C$에서 20분간 열처리하는 것이 적절한 조건인 것으로 조사되었다.