• Korean Journal of Materials Research
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• v.11 no.11
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• pp.915-922
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• 2001

Effects of thermal exposure and rejuvenation treatment on the microstructural evolution and the stress-rupture properties of IN738LC have been investigated. The role of precipitates on the stress-rupture properties has been analyzed through microstructural observations. Thermal exposure at $982^{\circ}C$ for 1000 hours gave rise to precipitation of $\sigma$ phase and coarsening of r'. The microstructural degradation with thermal exposure at $982^{\circ}C$ deteriorated stress rupture properties of the alloy. All the existing phases except MC carbides have completely dissolved into the matrix with homogenization treatment at $1200^{\circ}C$ for 2 hours. Microstructure and stress-rupture properties of the thermal exposed specimens have been successfully rejuvenated by the proposed treatment.

• Korean Journal of Materials Research
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• v.11 no.10
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• pp.833-840
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• 2001

Effects of thermal exposure and rejuvenation treatment on the microstructural evolution and the stress-rupture properties of IN738LC have been investigated. The role of precipitates on the stress- rupture properties has been analyzed through microstructural observations. Thermal exposure at $982^{\circ}C$ for 1000 hours gave rise to precipitation of $\sigma$ phase and coarsening of ${\gamma}$'. The microstructural degradation with thermal exposure at $982^{\circ}C$ deteriorated stress rupture properties of the alloy. All the existing phases except MC carbides have completely dissolved into the matrix with homogenization treatment at $1200^{\circ}C$ for 2 hours. Microstructure and stress-rupture properties of the thermal exposed specimens have been successfully rejuvenated by the proposed treatment.

• Journal of Drive and Control
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• v.18 no.2
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• pp.1-8
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• 2021

In this work, a circuit with a hydraulic power unit is formulated as a means of predicting the behavior of the prefill valve in the future. The behavior of the prefill valve can be examined by the measurements of the configured power unit, and the performance is determined by using hydraulic pumps, relief valves, and hydraulic hoses that make up the power unit. In particular, pressure/flow pulsation generated by hydraulic pumps can cause instability in the prefill valve and cause noise-induced degradation of the overall performance and reliability of the hydraulic system containing the prefill valve. Therefore, to study the behavior and performance of the prefill valve in a relatively accurate manner, the prediction of the characteristics of the hydraulic power unit driving the prefill valve is very important. In this study, the pulsation characteristics of the hydraulic pump were analyzed to theoretically demonstrate its relationship with different settings of the power unit, such as relief valve pressure settings and the presence/absence of the hose.

• Proceedings of the KIPE Conference
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• 2017.11a
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• pp.167-168
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• 2017

This paper investigates to identify an optimal for analysis of battery behavior in system-level applications such as Battery Energy Storage Systems in Smart Grid infrastructures and Electrical vehicles. At system level applications, it is mandatory to check model for meaningful equivalency and practical ability for extension from unit cell to Battery stack. The investigation of current battery models in relation to their suitability for study and analysis of system level applications of battery helpful for identification of optimal model and it also provides an intuition and direction to develop the most suitable model, if such models are not available already.

• International Journal of Air-Conditioning and Refrigeration
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• v.7
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• pp.101-111
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• 1999

The effect of various conditions of frosting and defrosting on the defrosting behavior of a fin-tube heat exchanger has been examined experimentally. An electric heater is used for defrosting in a fin-tube heat exchanger. There are several local maxima in the water draining rate. The amount of residual water on the heat exchanger after completion of defrosting is kept constant due to surface tension on the heat exchanger. Without considering degradation of the thermal performance due to the frosting, the defrosting efficiency is improved with increasing amount of frost irrespective of the frosting condition. The defrosting behavior is affected by frosting density as well as frost accumulation, both of which vary with the experimental operating conditions. The heat loss to the surrounding air decreases, and melting and defrosting efficiencies show high values with decreasing heat input.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.707-710
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• 1999

Moisture content and intrinsic viscosity of antistatic polyethyleneterephthalate(PET) depending on the thermal stabilizer content was studied. The terminal moisture content of antistatic PET was a function of drying temperature rather than drying time. Intrinsic viscosity drop of antistatic PET after melt spinning increased with increasing moisture content of it. After melt spinning, intrinsic viscosity of antistatic PET was decreased due to the thermal degradation of polyoxyalkyleneglycol(POAG) component of antistatic agent. Triphenylphosphate(TPP) was more effective as a thermal stabilizer than trimethylphosphate(TMP). A little intrinsic viscosity drop after melt spinning was found in PET containing 300 ppm of TPP as a thermal stabilizer.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.26 no.2
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• pp.67-73
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• 2016

The degradation behaviors of TiN coating layers under thermo-mechanical stress were investigated in terms of comparison of finite element analysis (FEA) and experimental data. The coating specimen was designed to quarter cylinder model, and the pulsed laser ablation was assumed as heat flux condition. The FEA results showed that heat accumulation at the center of the laser-ablated spot occurred and principle stress was concentrated at the lower region of the coating layer. The microstructural observation revealed that surface melting and decrease of the coating thickness occurred in the TiN/Inconel 617 and the interfacial cracks formed in the TiN/Si. The delamination was caused by the mechanical stress from the center to the outside of the ablated spot as the FEA results expected. It was considered that the improvement of the thermal shock resistance was attributed to higher thermal conductivity of Si wafer than that of Inconel 617.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1559-1565
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• 2009

Resistivity changes and intermetallic growth after thermal aging of Matter tin-plated copper sheet for current collector in fuel cell were investigated to survey the diffusion of Cu into Sn in interface and surface. The results show that the intermetallic growth and resistivity depended on thermal aging temperature and dwell time. In Sn plate on a Cu substrate, Cu6Sn5(${\mu}$) and Cu3Sn(${\varepsilon}$) intermetallics layer were formed at plate/substrate interface. Cu6Sn5(${\mu}$) intermetallics layer gradually changed Cu3Sn(${\varepsilon}$). Moreover Cu get through Sn layer and it was diffused in the surface at $200^{\circ}C$. On the other hand, only Cu3Sn(${\varepsilon}$) intermetallics layer were formed at plate/substrate interface at $300^{\circ}C$. Consequently, the intermetallics formation, thermal condition and oxidation of surface, causes increase in the resistivity of Tin-plated copper sheet.

• Fibers and Polymers
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• v.7 no.1
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• pp.36-41
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• 2006

PVC and SAN are often mixed to compensate for the disadvantages of each polymer. Miscibility and thermal stability of PVC/SAN blend were investigated in this study by blending SAN polymer having 20, 24, 28, 32 % of acrylonitrile contents. Two polymers were mixed using a melt blending method with a single screw extruder. DSC thermogram was used to evaluate miscibility of the two polymers. SAN having 24 % of acrylonitrile showed the best miscibility with PVC. In order to evaluate degradation behavior, blended polymer was heat treated in DSC furnace and glass transition temperature was measured consecutively. Glass transition temperature increased continuously with annealing time due to degradation and cross-linking of polymer chains. Melt index of blended polymer was always higher than that of PVC.

• Journal of the Korean Society of Clothing and Textiles
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• v.33 no.12
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• pp.2002-2010
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• 2009

The degradation behavior of berberine is examined using GC-MS to select the fingerprint products that can be used to identify berberine dye in badly faded archaeological textiles. A total of $100^{\circ}C$ thermal and $H_2O_2/UV/O_2$ degradation systems were used to degrade berberine chloride 0.1% solution up to 408 hours. The samples were analyzed using the GC-MS. Dihydroberberine, 2-pteridinamine, 6,7-dimethyl-N-[(trimethylsilyl) oxy]-, and 8-methoxy-11-[3-methylbutyl]-11H-indolo[3,2-c]-quinoline, 5-oxide were detected as the major products of thermal degradation and identified as the fingerprint products for berberine dye at the early stage of degradation. Isobenzofuran-1,3-dione,4,5-dimethoxy-, 9H-fluorene,3,6-bis(2-hydroxyethyl)-,1,3-dioxolo[4,5-g]isoquinolin-5(6H)-one,7,8-dihydro-, and 3-tert-butyl-4-hydroxyanisole were detected as the major products generated by the $H_2O_2/UV/O_2$ degradation and identified as the fingerprint products for berberine dye under severe degradation conditions.