• Journal of the Korean institute of surface engineering
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• v.45 no.2
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• pp.70-74
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• 2012

In thermal barrier coating (TBC) systems, the life of the coating depends on thermally grown oxide (TGO) layer because most of the failure of TBCs occurs when TGO growth increases. In order to inhibit TGO growth, process was additionally carried out before the heat treatment of the TBC coating layer at $1200^{\circ}C$ in air. In the additional process, heat treatment in vacuum furnace of < $10^{-5}$ torr was conducted for 7 h and 14 h before the heat treatment. The area and length of TGO, as well as the crack length in the TBC were characterized using a scanning electron microscope (SEM). The TGO thickness and crack of specimens pre-heat treated in vacuum furnace were reduced by 45% compare to those heat treated in furnace. Consequently, pre-heat treatment in a vacuum furnace process lead to effective inhibition of growth of the TGO.

• 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.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.140-145
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• 2011

The aim of the present study is to derive optimized post heat treatment temperatures to get a proper formability for Ti/STS409L/Ti clad materials. These clad materials were fabricated by cold rolling followed by a post heat treatment process for 10 minutes at temperatures ranging from $500^{\circ}C$ to $850^{\circ}C$. The microstructure of the interface was observed using a Scanning Electron Microscope(SEM) and an Energy Dispersive X-ray Analyser(EDX) in order to investigate the effects of post heat treatment on the bonding properties of the Ti/STS409L/Ti clad materials. Diffusion bonding was observed at the interfaces with a diffusion layer thickness increasing with the post heat treatment temperature. The diffusion layer was composed of a type of(${\varepsilon}+{\zeta}$) intermetallic compound containing additional elements, namely, Fe, Ti and Ni. The micro Knoop hardness of the Ti/STS409L interfaces was found to increase with heat treatment up to $800^{\circ}C$ and then decrease for temperatures rising up to $850^{\circ}C$. The tensile strength was shown to decrease for heat treatment temperature increasing to $750^{\circ}C$ and then increase rapidly for temperature rising up to $850^{\circ}C$. A post heat treatment temperature range of $700{\sim}750^{\circ}C$ was found to optimize the formability of Ti/STS409L/Ti clad materials.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.78-84
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• 2001

This study deals with the heat-treatment technique of SM45C steel with respect to less of deformation in control. The whole process for the production of landing gear must go through with uniformally controlled heat treatment, where as most deformation usually occur in nonuniform cooling environment. When a heated metal is submerged into a certain quenchant, the rate of cooling rapidity can be measured rather slow during the early stage of the procedure due to an Occurrence of a vapor blanked. As the additional course of cooling action is applied and the vapor from a vapor blanked is destroyed simultaneously, the speed of cooling promptness can be considered rather swift. The object of this study is to control the certain deformations as in the procedure of a heat treatment for landing gear by analyzing and improving the conditions of different substance of quenching liquids. Several noticeable curves indicating the temperature variation on the ap-plied metals during the cooling procedures, along with detectable rates of water verses oil and that of different polymer solutions are illustrated.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.6
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• pp.256-262
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• 2019

The microstructural features and texture development by both hot rolling and hot forging in ${\gamma}-TiAl$ alloy were investigated. In addition, additional heat treatment after hot forging was conducted to recognize change of the microstructure and texture evolution. The obtained microstructural features through dynamic recrystallization after hot deformed ${\gamma}-TiAl$ were quite different because two kinds of formation process were occurred depending on deformation condition. However, analyzed texture tends to be random orientation due to intermediate annealing up to ${\alpha}+{\beta}$ region during the hot deformation process. After additional heat treatment, microstructure transformed into fully lamellar microstructure and randomly oriented texture was also observed due to the same reason as before. Tensile test at room temperature demonstrated that anisotropy of mechanical properties were not appeared and transgranular fracture was occurred between interface of ${\alpha}_2/{\gamma}$. As a result, it could be suggested that microstructural features influenced much more than texture development on mechanical properties at room temperature.

• Restorative Dentistry and Endodontics
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• v.19 no.1
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• pp.135-147
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• 1994

This study was conducted to evaluate whether the fatigue toughness of visible light cured composite resins could be improved and how much percentage of polymerzation shrinkage could be affected by additional heat treatment. 7 materials were investigated for this study: P-50, Lite-fil CR inlay, Pekafil, Clearfil CR inlay, Clearfil photo posterior, Z -100 and Progress. Diametral tensile strengths and linear shrinkages of composite resins were taken under visible light cured and additional post-cure heated condition and compared each other. A fatigue toughness of above materials was evaluated by measuring diametral tensile strength after they were repeatedly loaded with 120kgf/$cm^2$ up to 3000 cycles. The results obtained were as follows : 1. When composite resins were cured just by visible light, Lite fil CR inlay, Z -100 and Progress showed respectively higher diametral tensile strength than the other materials. Clearfil CR inlay, Clearfil photo posterior and Progress exhibited strong fatigue toughness compared to P-50 and Pekafil. 2. Post-cure heat treated composite resins had higher diametral tensile strengths than visible light cured composite resins at fatigue toughness test as well as no fatigue toughness test. 3. When Composite resins were additionally polymerized by post-cure heat treatment, P-50 showed weak fatigue toughness, on the contrary, Clearfil CR inlay, Z-100, Progress showed strong one. 4. When composite resins were cured just by visible light, percentage of polymerization linear shrinkage was the lowerest in Clearfil CR inlay, followed by, in ascending order, Clearfil photo posterior, Lite-fil CR inlay, Progress, Pekafil, P-50, and Z-100. In the case of post- cure heat treated composite resins, percentage of linear shrinkage was the lowest in Clearfil photo posterior, followed by, in ascending order, Lite-til CR inlay, Clearfil CR inlay, Progress, P-50, Pekafil and Z-100. 5. Percentage of polymerization linear shrinkage was greater in the post-cure heat treated composite resins than in the visible light cured composite resins and linear shrinkage increased significantly in Pekafil, Clearfil CR inlay, and Clearfil photo posterior between at the visible light cured and at the post-cure heat treated condition. The above results is saying that additional post-cure heat treatment on the composite resins for posterior restoration is able to affect on improvement of strength and fatigue toughness and lead to increase polymerization of composite resins.

• Journal of Magnetics
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• v.20 no.2
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• pp.155-160
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• 2015

Recently, $CO_2$ emission standards and fuel efficiency legislation has been tightened globally. Therefore automotive alternator performance becomes increasingly important to meet the requirements. Many proposed methods have suggested adding magnets or regulation control to increase alternator efficiency and output. However, this creates a significant additional cost. During the stator lamination process, the magnetic property of the stator deteriorates mainly due to stamping and slinky process for an alternator. To maximize the alternator performance, heat treatment of the stator core was performed and magnetic properties were compared to find the optimal condition. Finally, alternator output and efficiency test were performed resulting in significant output and efficiency improvement up to 6.8% and 0.6% respectively.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.2
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• pp.66-74
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• 2021

Cladding material, which can selectively obtain excellent properties of different metals, is a composite material that combines two or more types of dissimilar metals into one plate. The titanium-copper cladding material between titanium which has excellent corrosion resistance and copper which has high thermal and electrical conductivity, are highly valuable composite materials. It can be used as heat exchangers with high conductivity under severe corrosion conditions. In order to apply the clad plate to the heat exchanger, it must be manufactured in the form of a tube and additional welding is required. It is important to select the cladding material manufacturing process and the welding process. The process of manufacturing the cladding material includes extrusion, rolling, and explosive bonding. Among them, the explosive bonding process is suitable for additional welding because no heat-affected zone is formed. In this study TIG welding of the explosive-bonded dissimilar clad plates was successfully performed by butt welding. The microstructures and bonding interface of the welded part were observed, and the effect of the bonding layer at the welding interface and the intermetallic compounds on the mechanical properties and tensile plastic deformation behaviors were analyzed. And also the integrity of TIG-welded dissimilar part was evaluated.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.322-322
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• 2010

For boron doping on n-type silicon wafer, around $1,000^{\circ}C$ doping temperature is required, because of the relatively low solubility of boron in a crystalline silicon comparing to the phosphorus case. Boron doping by fiber laser annealing and lamp furnace heat treatment were carried out for the uniformly deposited p-a-Si:H layer. Since the uniformly deposited p-a-Si:H layer by cluster is highly needed to be doped with high temperature heat treatment. Amorphous silicon layer absorption range for fiber laser did not match well to be directly annealed. To improve the annealing effect, we introduce additional lamp furnace heat treatment. For p-a-Si:H layer with the ratio of $SiH_4:B_2H_6:H_2$=30:30:120, at $200^{\circ}C$, 50 W power, 0.2 Torr for 30 min. $20\;mm\;{\times}\;20\;mm$ size fiber laser cut wafers were activated by Q-switched fiber laser (1,064 nm) with different sets of power levels and periods, and for the lamp furnace annealing, $980^{\circ}C$ for 30 min heat treatment were implemented. To make the sheet resistance expectable and uniform as important processes for the $p^+$ layer on a polished n-type silicon wafer of (100) plane, the Q-switched fiber laser used. In consequence of comparing the results of lifetime measurement and sheet resistance relation, the fiber laser treatment showed the trade-offs between the lifetime and the sheet resistance as $100\;{\omega}/sq.$ and $11.8\;{\mu}s$ vs. $17\;{\omega}/sq.$ and $8.2\;{\mu}s$. Diode level device was made to confirm the electrical properties of these experimental results by measuring C-V(-F), I-V(-T) characteristics. Uniform and expectable boron heavy doped layers by fiber laser and lamp furnace are not only basic and essential conditions for the n-type crystalline silicon solar cell fabrication processes, but also the controllable doping concentration and depth can be established according to the deposition conditions of layers.

• Journal of Korea Foundry Society
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• v.13 no.5
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• pp.432-440
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• 1993

Ductile cast iron has a good ductility and toughness than those of gray cast iron, because the shape of graphite is spheroidal. Also, it has been reported that, additional strengthening and toughening of the ductile cast iron can be obtainded from the proper combination of matrix structures by the heat treatment and addition of alloying elements. In this study the effect of special heat treatment and addition of alloying elements(Ni, Mo) on the multi-phase(ferrite-bainite-martensite) structures, strength and toughness of ductile cast iron were studied systematically. In water quenching from $770^{\circ}C$, the martensite volume(%) increased, but the ferrite volume(%) decreased with increment of Ni content. In as cast, pearlite volume(%) and hardness increased with increment of Mo and Ni contents. And with the increment of the destabilization austempering holding time, the bainite volume(%) increased but the martensite volume(%) decreased. As destabilization austempering holding time is same, bainite volume(%) decreased, martensite increased with the increment of Ni and Mo contents. The hardness and tensile strength decreased, but impact energy increased with the decrease of Ni and Mo contents, and increment of holding time of destabilization austempering treatment.