• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.83-88
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• 2019

In this study, the high-temperature high-pressure vessel was successfully manufactured, which can be used to store pressurized air and to increase the temperature for the mix performance test of high-temperature high-pressure air with coolant (e.g., water). In this research, static structure analysis and transient thermal analysis were performed using the commercial software Midas NFX 2015 R1. Based on the results, the optimized pressure vessel design was carried out. As a result of the optimized design, the minimum stress and minimum weight were found at 120 mm of the vessel thickness, and the optimized pressure vessel was verified. Finally, through manufacture and performance test (e.g., the non-destructive inspection and hydraulic pressure test), the reliability and safety were validated for the designed pressure vessel.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.4
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• pp.68-75
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• 2018

This study presents the performance test results and the analyses of the vitiated air heater with high temperature and high pressure. In the performance test, four test conditions and three rake measurement conditions were implemented. In the results of the performance test, the vitiated air heater met targets of temperature and flow rate, and the performance with maximum temperature of 2000 K and maximum combustion pressure of 40 bar was confirmed. Flow rate of provided methane increased 36% more than what was calculated, and 19.6% difference was displayed between measured temperature and theoretically calculated temperature.

• Corrosion Science and Technology
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• v.7 no.1
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• pp.61-67
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• 2008

In this paper, electrochemical and microstructural characteristics of nickel-plated Alloy 600 were investigated in order to identify the performance of electroless Ni-plating on Alloy 600 in high-temperature aqueous condition with the comparison of electrolytic nickel-plating. For high temperature corrosion test of nickel-plated Alloy 600, specimens were exposed for 770 hours to typical PWR primary water condition. During the test, open circuit potentials (OCP's) of all specimens were measured using a reference electrode. Also, resistance to flow accelerated corrosion (FAC) test was examined in order to check the durability of plated layers in high-velocity flow environment at high temperature. After exposures to high flow rate aqueous condition, the integrity of surfaces was confirmed by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). For the field application, a remote process for electroless nickel-plating was demonstrated using a plate specimen with narrow gap on a laboratory scale. Finally, a practical seal design was suggested for more convenient application.

• Advances in concrete construction
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• v.10 no.2
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• pp.113-125
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• 2020

This paper presents experimental results on bond-slip behavior of steel reinforced high-strength concrete (SRHC) after exposure to elevated temperatures. Three parameters were considered in this test: (a) high temperatures (i.e., 20℃, 200℃, 400℃, 600℃, 800℃); (b) concrete strength (i.e., C60, C70, C80); (c) anchorage length (i.e., 250 mm, 400 mm). A total of 17 SRHC specimens subjected to high temperatures were designed for push out test. The load-slip curves at the loading end and free end were obtained, the influence of various variation parameters on the ultimate bond strength and residual bond strength was analyzed, in addition, the influence of elevated temperatures on the invalidation mechanism was researched in details. Test results show that the shapes of load-slip curves at loading ends and free ends are similar. The ultimate bond strength and residual bond strength of SRHC decrease first and then recover partly with the temperature increasing. The bond strength is proportional to the concrete strength, and the bond strength is proportional to the anchoring length when the temperature is low, while the opposite situation occurs when the temperature is high. What's more, the bond damage of specimens with lower temperature develops earlier and faster than the specimens with higher temperature. From these experimental findings, the bond-slip constitutive formula of SRHC subjected to elevated temperatures is proposed, which fills well with test data.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2001.11a
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• pp.59-62
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• 2001

Flow induced vibration in steam generators has caused dynamic interactions between tubes and contacting materials resulting in fretting wear . Series of experiments have been performed to examine the wear properties of Inconel 690 steam generator tubes in various environmental conditions. For the present study, the test rig was designed to examine the fretting wear and rolling wear properties in high temperature(room temperature - 290。C) water. The test was performed at constant applied load and sliding distance to investigate the effect of test temperature on wear properties of the steam generator tube materials. To investigate the wear mechanism of material, the worn was observed using scanning electron microscopy. The weight loss increase at higher test temperature was caused by the decrease of water viscosity and the mechanical property change of tube material. The mechanical property changes of steam generator tube material, such as decrease of hardness or yield stress in the high temperature tests. From the SEM observation of worn surfaces, the severe wear scars were observed in specimens tested at the higher temperature.

• Korean Journal of Materials Research
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• v.23 no.10
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• pp.568-573
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• 2013

The deformation properties of a TiC-Mo eutectic composite were investigated in a compression test at temperatures ranging from room temperature to 2053 K and at strain rates ranging from $3.9{\times}10^{-5}s^{-1}$ to $4.9{\times}10^{-3}s^{-1}$. It was found that this material shows excellent high-temperature strength as well as appreciable room-temperature toughness, suggesting that the material is a good candidate for high-temperature application as a structure material. At a low-temperature, high strength is observed. The deformation behavior is different among the three temperature ranges tested here, i.e., low, intermediate and high. At an intermediate temperature, no yield drop occurs, and from the beginning the work hardening level is high. At a high temperature, a yield drop occurs again, after which deformation proceeds with nearly constant stress. The temperature- and yield-stress-dependence of the strain is the strongest in this case among the three temperature ranges. The observed high-temperature deformation behavior suggests that the excellent high-temperature strength is due to the constraining of the deformation in the Mo phase by the thin TiC components, which is considerably stronger than bulk TiC. It is also concluded that the appreciable room-temperature toughness is ascribed to the frequent branching of crack paths as well as to the plastic deformation of the Mo phase.

• Journal of the Korean Society of Systems Engineering
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• v.17 no.1
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• pp.97-106
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• 2021

The purpose of the study on the tailoring of environmental requirements for KT-1 Export Version(XKT-1T) aircraft is not only based on meeting the compliance of the environmental reliability, customer satisfaction, but also for the expansion of its export. This paper proposes the environmental requirements tailoring processes and High/Low temperature conditions, test procedures, and the results of test profiles for the aircraft. Amongst many existing environmental requirements, the temperature requirements are considered as the most basic and the most important environmental requirements. The High/Low temperature tests are considered and tailored to the high and low temperature methods of MIL-STD-810.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.379-380
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• 2002

Steam generators (S/G) of pressurized water reactors are large heat exchangers that use the heat from the primary reactor coolant to make steam in the secondary side for driving turbine generators. Reciprocating sliding wear experiments have been performed to examine the wear properties of Incoloy 800 and Inconel 690 steam generator tubes in high temperature water. In present study, the test rig was designed to examine the reciprocating and rolling wear properties in high temperature (room temperature - $300^{\circ}C$) water. The test was performed at constant applied load and sliding distance to investigate the effect of test temperature on wear properties of steam generator tube materials. To investigate the wear mechanism of material, the worn surfaces were observed using scanning electron microscopy. At $290^{\circ}C$, wear rate of Inconel 690 was higher than that of Incoloy 800. It was assumed to be resulted from the oxide layer property difference due to the a\loy composition difference. Between 25 and $150^{\circ}C$ the wear loss increased with increasing temperature. Beyond $150^{\circ}C$, the wear loss decreased with increasing temperature. The wear loss change with temperature were due to the formation of wear protective oxide layer. From the worn surface observation, texture patterns and wear particle layers were found. As test temperature increased, the proportion of particle layer increased.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.69-74
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• 2003

This study evaluated durability through measurement of substituted test piece's pH degree and experiments of neutralization. Comparing and evaluating cared test piece's pH degrees which we got before the neutralization and after the neutralization. After evaluating neutralization depth through neutralization, evaluating neutralization properties by Fly Ash replacement ratio. pH degree was decreased by cement replacement ratio of Fly Ash. And in the case of substitution of the same amount of Fly Ash, fine aggregate replacement ratio was increased. When the test piece, which had been cared in high temperature, was promoted to neutralization, Among the test piece which was replaced with Fly Ash 40%, the test piece which has high rate of fine aggregate proved opposition of neutralization Through the test, Ⅰ summarized that the test piece cared in high temperature was mostly effected by compress strength, the test piece cared in low temperature was mostly effected by pH degree.

• Journal of Applied Reliability
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• v.17 no.1
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• pp.22-27
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• 2017

Purpose: The purpose of this study is to estimate the life time of OLED TV panel through electric current ADT(Accelerated Degradation Test). Methods: We performed accelerated degradation test for OLED TV Panel at the room temperature to avoid high temperature impact on the luminance. Results: we got more accurately the life time of the OLED TV when we applied ADT without temperature factor than including both current and temperature. Conclusion: Until now, the ADT of the OLED TV has been conducted with temperature and current at the same time for reducing test time and costs. We estimate incorrect life time when the temperature is adopted as an accelerated factor. Due to the high temperature impact on the luminance of the OLED TV panel. So as to solve this problem, we discard temperature and use electric current only.