• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.281-284
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• 2003

The microstructural changes of Al-Zn-Mg-Cu alloy containing Sc during hot extrusion and post heat treatment is investigated. Two kinds of Al-Sc alloys with different alloying elements (B1, B2) are hot extruded to make I-shape bars at 380$^{\circ}C$, then the bars are solution treated at 480$^{\circ}C$ for 2hrs followed by artificial aging at 120$^{\circ}C$ for 24hrs. The interior microstructure of as extruded bar consists of elongated grains, however, fine equiaxed grains are mainly observed around surface. The microstructural gradient suggests that different restoration process can proceed during the hot extrusion. For B1 and B2, different grain growth behaviors are found around the surface during the post heat treatment. Rapid grain growth behavior around the surface is discussed related with the crystallographic orientation of the grain.

• 원예과학기술지
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• 제32권1호
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• pp.26-32
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• 2014

본 연구에서는 종자전염병의 무독화를 위해 실시하는 건열처리에 의한 종자의 활력감소를 회복시키기 위한 방법을 개발하고자 하였다. 건열처리된 종자의 활력감소 정도는 작물과 품종에 따라 다양하게 나타났다. 일반적으로 호박 종자가 박 종자에 비하여 활력이 덜 감소하였다. 건열처리된 종자를 0, 30, 120일간 후처리하였을 때, 발아율은 건열처리 후처리 기간이 증가함에 따라 높아졌는데, 후처리 효율은 작물과 품종에 따라 상이하였다. 또한, 박과 호박 종자를 상향 또는 수평 파종 시 하향 파종보다 높은 종자활력과 묘소질을 보였다. 따라서 건열처리에 의한 종자활력의 감소는 적절한 후처리 뿐만 아니라 상향파종을 통해서도 효과적으로 회복시킬 수 있음을 확인하였다.

• 대한한방소아과학회지
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• 제14권2호
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• pp.133-140
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• 2000

Purpose : Posterior Neck Pain and Back Pain are common diseases in human daily life. For reducting symptom and treatment of these diseases, many methods have been used and studied until now. The mechanisms of Ceragem Master Heat Bed(R)(Ceragem Co. Seoul, Korea) are infrared-heat therapy from natural nephrite and pressure therapy by up-down movement of natural nephrite ball. Through this study, authors would evaluate the clinical effectiveness of Ceragem Master Heat Bed(CMHB) on relieving posterior neck pain and back pain. Materials and methods : From 12-01-2000 to 01-13-2001, posterior neck pain and back pain patients were selected for experiment group(23patients) and control group(14patients). In both group, Visual Analog Scale(VAS) of pre-treatment stage is above 5 points. Experiment group were cared with acupuncture therapy, buhang therapy and CMHB. Control group were managed with only acupuncture therapy and buhang therapy. They were treated more than three times at least. At pre-treatment and post-treatment stage, we measured VAS for individual patients, and then compared effect of treatment in experiment group and in control group. Statistical analysis was preformed using SAS program. Results : In this study, a mean difference of VAS between pre-treatment and post-treatment stage was large in experiment(CMHB) group more than in control group(p〈0.01). Conclusion : Experiment(CMHB) group was more effective pain relief than control group in the treatment of posterior neck pain and back pain. CMHB was available for stimultaneous application of heat therapy and pressure massage together that gave another effects of mental stability and fatigue recovery. As the results of this study, CMHB could be used as a helpful treatment modality for posterior neck pain and back pain.

• 한국해양공학회지
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• 제23권6호
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• pp.105-110
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• 2009

The objective of this paper is to investigate the statistical properties of Vickers hardness (HV) for friction welded parts in a Ni-based super alloy (Alloy718). In the case of post weld heat treatment (PWHT) parts, hardness tests were repeated for three different applied loads, 100, 200, and 300 g, with a duration time of 10 seconds. The arithmetic means of the Vickers hardness in heat affected zone (HAZ) materials were smaller than those of the base metal (BM) in all of the applied loads. The coefficient of variation (COV) for the BM and HAZ decreased by increasing the applied load. The probability distribution of the Vickers hardness followed the Weibull distribution well. The distribution of the Vickers hardness was not found to be symmetric. The shape parameter and scale parameter increased by increasing the applied load at both the BM and HAZ.

• Journal of Welding and Joining
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• 제14권3호
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• pp.75-85
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• 1996

In this paper the influence of postweld heat treatment on mechanical properties of SMAW and FCAW stainless steel weldments was examined and the obtained results are as follows ; (1) The amount of $\delta$-ferrite formed by SMAW and FCAW process decreased with increasing holding temperature and time in post weld heat treatment(PWHT), and it was found that the reduced ferrite was transformed into sigma phase after $800^{circ}C{\times}50hr$ PWHT. This sigma phase, even though it was very small, resulted in brittleness of dissimilar weldment between carbon steel and stainless steel in bending test, however in similar weldment between stainless steel and stainless steel was not occured. (2) The chemical composition of sigma phase was measured to 28-30%Cr, 7-9%Mo, 4-6Ni in 316L weldment, and also 35-37%Cr, 0.9-1.0Mo, 6-8%Ni in 309L weldment by EDS analysis.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.789-794
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• 2008

Zinc oxide (ZnO) has been widely studied for its practical applications such as transparent conduction electrodes for flat panel displays and solar cells. Especially, ZnO films show good chemical stability against hydrogen plasma, absence of toxicity, abundance in nature, and then suitable for photovoltaic applications. However, the fabrication process of thin film solar cells require a high substrate temperature and/or post heat treatment. Therefore, the layers have to withstand high temperatures, requiring an excellent stability without degrading their electronic and optical properties. In this paper, we investigated the stability of zinc oxide (ZnO) films doped with aluminum and hydrogen. Doped ZnO films were prepared by r.f. magnetron sputter and followed by heat treatment at different temperatures and for various times.

• 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.

• 대한금속재료학회지
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• 제47권3호
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• pp.139-146
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• 2009

The heat-affected zone (HAZ) of SA508 Gr.4N Ni-Mo-Cr low alloy steel, which has higher Ni and Cr contents than SA508 Gr.3 Mn-Mo-Ni low alloy steel, was investigated on the microstructure and mechanical properties. The HAZ was categorized into seven characteristic zones (CGCG, FGCG, ICCG, SCCG, FGFG, ICIC and SCSC-HAZ) according to the peak temperature from the thermal cycle experienced during multi-pass welding. Post Weld Heat Treatment (PWHT) was conducted in the temperature range of $550{\sim}610^{\circ}C$ for 30 hours to evaluate the effect of PWHT conditions on the microstructure and mechanical properties. Before PWHT, CGHAZ and FGFGHAZ showed high yield strength (YS) ranging from 1000 to 1250 MPa, while YS of SCSCHAZ decreased from 607 MPa (observed for base metal) to 501 MPa. The Charpy impact energies of sub-HAZs fell below 100J at $-29^{\circ}C$, except in the SCSCHAZ. By applying PWHT to sub-HAZ specimens, YS decreased as the PWHT temperature increased. In the case of CGHAZs and FGFGHAZ heat-treated at $610^{\circ}C$, YS dropped drastically to the range of 654~686 MPa. From the Charpy impact test, the upper-shelf energy (USE) increased to approximately 250J and Index temperature ($T_{68J}$) decreased below $-50^{\circ}C$. Specifically, in FGFG, ICIC and SCSC-HAZ, $T_{68J}$ was below -110, which was lower than the case of base metal.

• 한국결정성장학회지
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• 제30권1호
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• pp.12-16
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• 2020

RF 마그네트론 스퍼터링법으로 투명 PI 기판 위에 상온 증착된 ITO(indium tin oxide) 박막을 여러 온도(50, 100, 150 그리고 200℃)에서 열처리하였다. 열처리 온도에 따른 ITO 박막의 전기적, 광학적 특성과 결정성의 변화를 조사하였다. 상온 증착된 ITO 박막은 비정질 구조를 가지며 열처리 온도가 증가할수록 결정성과 결정립 크기가 증가하였다. 이러한 구조적 변화와 더불어 전하 캐리어 농도와 이동도가 증가함으로써 비저항은 열처리 온도가 50℃에서 200℃로 증가함에 따라 2.93 × 10^-3 Ω·cm에서 1.21 × 10^-4 Ω·cm로 감소하였다. ITO가 증착된 PI 기판의 투과도는 열처리함으로써 감소하였다. 50~150℃ 온도에서는 81 % 이상이었고 200℃에서는 78 %로 상당히 감소하였다.

• 대한치과기공학회지
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• 제35권4호
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• pp.271-280
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• 2013

Purpose: This study was to assess the effect of surface and heat treatment on the bond strength of veneering ceramics to zirconia. Methods: The specimens were divided into 7 groups according to surface treatment and heat treatment conditions prior to porcelain application. ten specimens from each group were subjected to a 3-point flexural test. In addition the influence of surface and heat treatment on surface roughness values and phase transformation of zirconia was evaluated. Statistical analysis was performed with one-way ANOVA and post hoc Tukey's test. Results: Bond strength ranged from $20.67{\pm}3.13MPa$ to $32.69{\pm}4.52$. Bond strength of surface treatment group was lower than that of control group but only $Al_2O_3$ sandblasting group was significant difference. Bond strength of heat treatment group was higher than that of surface treatment group but there was no statistical significance. Conclusion: Bond strength of veneering ceramics to zirconia was affected by surface and heat treatment.