• Transactions of Materials Processing
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• v.30 no.2
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• pp.61-68
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• 2021

As part of efforts to reduce the weight of automotive body-in-white, a hybrid center pillar with high strength 7075 aluminum alloy (AA7075) sheet and carbon fiber reinforced plastic (CFRP) has been recently studied. In the fabrication of the AA7075-CFRP hybrid center pillar, the AA7075 sheet might go through heating-forming-in-die quenching (HFQ), artificial aging, hybridizing, and then paint baking processes. In this study, we investigate the effects of the heat treatment history associated with each process on the tensile strength of the AA7075 sheet. Typical heat treatment conditions are HFQ for 20 minutes at 480℃ and then cooling down with die, artificial aging of T6 temper for 24 hours at 120℃, hybridizing for 10 minutes at 150℃, and paint baking for 20 minutes at 180℃. The tensile strength of the AA7075 sheet is continuously increased by a series of heat treatments of hybridizing and paint baking and is expected to have yield stress above 500MPa without artificial aging of T6 temper.

• Journal of the Korean Society for Heat Treatment
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• v.2 no.2
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• pp.11-16
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• 1989

Understanding and control of thermal history of heat-treated components are very important in heat treating process. A computer program was developed for prediction of thermal history in quenching process with various cooling media and agitation conditions. Computer simulation of heat flow in quenching treatment of spur gear of SCM 22 H was carried out by two and three dimensional finite difference method. Distributions of microstructure and hardness in heat-treated spur gear were predicted by computer simulation, and the results showed a good agreement with the experiments. It was concluded that the

• The Journal of Korean Medical History
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• v.22 no.1
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• pp.57-67
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• 2009

The results of analyzing "Shanghanlun-Shanghan examples" of Song Dynasty Text and Liuwansu's writings in the pursuit of comprehending his views written in "Fire-Heat" & "Warm disease" -are as follow. 1.He introduced Exterior-Interior Shanghan and Latent in the Winter & recurrent in the Spring Shanghan concept in the Febrile disease pathology as the link and the bifurcation point. His perception on Febrile disease encompassed Shanghan and Febrile disease on the same plane but actually discriminated in the treatment and medication between the two actually. 2.He suggested Febrile disease pathology in the concept of Shanghan and Febrile disease, which is coherent in the formation of interior heat as the result of the invasion of the lung by warm pathogen described in Warm disease Wei, Qi, Ying and Xue Fen Syndrome differentiation. He expanded the concept of esoteric portal 玄府 of "Suwon Tiaojinglun", to that of the omni-present portal & way of Qi's all directions movement, which is in accordance of invasion of upper energizer 上焦 by warm or hot pathogen via mouth and nose as used in Warm disease three-energizer differentiation. 3.He recognized both exterior-interior febrile disease in the context of both exterior-interior contact cause disease. He prescribed pungent-cool exterior releasing medicinal similar to that of exterior-releasing treatment adopted in warm disease. As lily-talc powder百合散 introduced in "Golden chamber synopsis" dispells heat by promoting excretion of urine and defecation, it is regarded as the original formula of later ikwonsan yiyuansan 益元散.

• 한국기계연구소 소보
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• s.16
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• pp.3-16
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• 1986

The first specimens were sampled across the depth of roll products processed by rapid heating and cooling of the roll, namely, differential heat treatment. The second samples were taken from the non-heat treated roll at different depths. The samples were heat treated following the same temperature history as that at each corresponding location in the roll where the samples were taken. Consequently, both specimens showed the similar microstructure and mechanical properties (tensile, impact and fatigue strength etc.)

• Journal of the Korean Society for Heat Treatment
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• v.23 no.6
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• pp.323-330
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• 2010

The present study was motivated by increasing demands on quantitative measurements of the heat flux through the water cooling and quenching process of hot steel. The local heat flux measurements are employed by a novel experimental technique that has a function of high-temperature heat flux gauge in which test block assemblies are directly used to measure the heat flux variation during water cooling and quenching of hot steel. The heat flux can be directly achieved by Fourier's law and is also compared with numerical estimation which is solved by inverse heat conduction problem (IHCP). The high-temperature heat flux gauge developed in this study can be applicable to measure cooling rate and history during the actual cooling applications of steelmaking process. In addition, the measurement uncertainty of heat flux is calculated by a quantitative uncertainty analysis which is based on the ANSI/ASME PTC 19.1-2005 standard.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.05a
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• pp.313-316
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• 2005

In the present study, Bauschinger effect was investigated for the micro-alloying forging steel which has been developed for about 30 years ago to save energy consumption by eliminating the heat treatment processes in the forging industry. The micro-alloying steels used fur cold forging industry mainly aim to replace the usual carbon steel. With the conventional carbon steels, all the deformation history can be eliminated after the final heat treatment(quenching and tempering). In the case of micro-alloying forging steels, however, the prior deformation history should be taken into consideration to meet the mechanical property requirement since the microstructure of micro-alloying steels might exhibit the Bauschinger effect, which was not needed to consider in the case of conventional carbon steel having quenching and tempering treatment. In the present study, the reverse loading tests were carried out to determine the Bauschinger effect of micro-alloying steel which composed of ferrite and cementite phases.

• Journal of Welding and Joining
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• v.11 no.4
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• pp.103-111
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• 1993

Recently, several high-tensile steels(e.g. 80kg and above, $2^{1/4}Cr$-1Mo)having good quality to high temperature and pressure-resistance are widely used to construct petroleum-plant and pressure vessel of heat or nuclear-power plant. However, in the steels, reheating crack at grain boundaries of the heat affected zone(HAZ) occures during post welding heat treatment(PWHT)to remove welding residual stress. In order to study theoretically the characteristics of reheating crack created by PWHT, the computer program of three-dimensional thermal-elasto-plasto-creep analysis based on finite element method are developed, and then the mechanical behavior(history of creep strain accumulation and stress relaxation, etc)of welded join in thick plate during PWTH is clarified by the numerical results.

• The Journal of Korean Medical History
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• v.19 no.2
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• pp.87-100
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• 2006

Jang Jong-jeong thought that, because all diseases come from miasma, for treating diseases, it is important to attack or remove miasma infiltrating into the body. Thus, he treated diseases using three methods, namely, vomiting against miasma on the top, sweating against miasma on the surface, and diarrhea against miasma on the bottom. Among them, vomiting is rarely used in contemporary Oriental medicine, but still one of major disease treatment methods. Vomiting is quite meaningful in today's clinics and particularly effective for acute diseases, the miasma of which is in the upper chest. According to the present researcher's experiences, it is effective in cases that the pathological symptoms are observed in the upper chest such as early stroke, dyspepsia, chest congestion and congestion heat. For vomiting, the researcher applied Dokseongsan, Samseongsan, Gwachesan, Gangyeomtang, Bangpungtongseongsan, etc. Dokseongsan was used for vomiting in a cool way, and Samseongsan and Gwachesan were used for vomiting in a warm way. Bangpungtongseongsan was used when inner heat was choked up by the attack of external miasma and when the pathological symptoms of Bangpungtongseongsan were observed.

• The Journal of Korean Medical History
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• v.33 no.2
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• pp.129-145
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• 2020

This study studied the use of Woohwanggo in the Joseon royal family through The daily records of Royal secretariat of Joseon Dynasty, which contains detailed records of royal medical treatment. The study found that Woohwanggo was mainly used for diseases related to vexing heat (煩熱), fumigating heat (薰熱), night fever (夜間發熱), and heat syndrome (熱證) from smallpox, and measles in the royal family of Joseon. This study also confirmed that Woohwango was used in various ways within the Daily records of Royal secretariat of Joseon Dynasty, including the way it was taken with various types of tea, the way it was made into liquid form, and the way it was used as an external agent for skin diseases. Further findings were compared to the medical books, and the dosage characteristics of Woohwango in the daily records of Royal secretariat of Joseon Dynasty were discussed. and the medical perception of King Yeongjo (英祖), which was examined during the study, was also discussed.

• Journal of the Korean Society for Heat Treatment
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• v.2 no.2
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• pp.1-10
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• 1989

In this study, the specimens of SCM 22 H steel were quenched in oil and water baths at various agitation conditions in order to investigate the effects of quenchants and agitation conditions on the quench-hardening. A multi-channel temperature measurement apparatus was employed to obtain the cooling curves at several predetermined positions of specimens. Microstructural observation and hardness test were also carried out. Computer simulation of heat treating process was carried out using the modified finite difference method. Prediction of thermal history and hardness distribution by 2-dimensional computer analysis was in good agreement with the experimental results. It was found that the quantitative design of heat treating process can be made by the computer aided heat-treating analysis.