• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.190-195
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• 2002

The intermittent high vibration has been occurred one or two times a day for a 500MW large steam turbine during 5 months. This abnormal vibration was caused by the rubbing between the rotor and the carbide accumulated on the seal tooth of oil deflector. It was found that the accumulated carbide was insulation material installed on the HIP casing from the examination of the chemical composition. Also, this paper presents the mechanism of the intermittent high vibration and the proper method to eliminate this vibration problem. This result would be good practice to find the solution of similar high vibration in the steam turbines for power plant as well as industrial rotating machineries.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.11
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• pp.897-903
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• 2002

The periodic high vibration has been occurred one or two times a day for a 500 MW large steam turbine during 5 months. This abnormal vibration was caused by the rubbing between the rotor and the carbide accumulated on the seal tooth of oil deflector. It was found that the accumulated carbide was insulation material installed on the HIP casing from the examination of the chemical composition. Also, this paper presents the mechanism of the periodic high vibration and the proper method to eliminate this vibration problem. This result would be good practice to find the solution of similar high vibration in the steam turbines for power plant as well as industrial rotating machineries.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.464-469
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• 2012

In the electric power plant, the shaft vibration is one of the very important point for successful long-term operation, because the high reliability unit needs stable rotor dynamic system. However, in the one combined cycle power plant, the abnormal high level shaft vibration analyzed 1 X on the journal bearing has been several times suddenly tripped of Gas turbine due to the accumulated oil carbide. This paper describes how to countermeasure the abnormal shaft vibration in the journal bearing of Gas turbine exhaust bearing in the field.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.211-212
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• 2002

Friction and wear of pressureless sintered Ti(C,N)-WC ceramics were studied using a ball-on-reciprocating flat apparatus in open air. The silicon nitride ball and the cemented carbide (WC-Co) ball were used against the Ti(C,N)-WC plate samples. The friction coefficients of the Ti(C,N)-WC samples against the silicon nitride ball and the cemented carbide ball were about 0.57 and 0.3, respectively. The wear coefficient of the sample without WC addition was 5 times as large as that of the sample with 10 mole % WC addition when tested against the silicon nitride ball under 98 N. The higher wear coefficient of Ti(C,N)-0WC was explained in part by larger grain size. Wear occurred mainly by grain dislodgment after intergranular cracking mainly caused by the accumulated stress within the grains.

• Nuclear Engineering and Technology
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• v.46 no.4
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• pp.475-480
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• 2014

We developed a simple method to prepare the displacement damage cross section of SiC using NJOY and SRIM/TRIM. The number of displacements per atom (DPA) dependent on primary knock-on atom (PKA) energy was computed using SRIM/TRIM and it is directly used by NJOY/HEATR to compute the neutron energy dependent DPA cross sections which are required to estimate the accumulated DPA of nuclear material. SiC DPA cross section is published as a table in DeCART 47 energy group structure. Proposed methodology can be easily extended to other materials.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.8
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• pp.1-8
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• 2022

Inconel 718 is nickel-based and is increasingly being used as a key component in the nuclear, aerospace, and chemical industries which require high fatigue strength and oxidation, because of its excellent corrosion resistance, heat resistance, and wear resistance. It is a heat-resistant alloy which has excellent mechanical properties; however, material deformation, cracking, and shaking occur because of the high cutting temperature accumulated on the cutting surface during cutting processing, and heat accumulated at the insert boundary. Owing to these characteristics, various studies have been conducted, such as developing a tool exclusively for non-deletion, analyzing tool wear, and developing a tool cooling system. However, the optimization of the cutting process is still insufficient. In this study, the optimal process conditions were derived experimentally by cutting conditions according to the insert type during the cutting of Inconel 718.

• Fire Science and Engineering
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• v.26 no.3
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• pp.35-39
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• 2012

This paper analyzes the combustion diffusion pattern when a water purifier is artificially ignited outside and inside in order to provide data to examine the cause of fire of a water purifier damaged by fire. The analysis result of the combustion diffusion pattern of a water purifier shows that the combustion diffused at a higher speed when it was ignited inside the purifier than when ignited outside. It took approximately 360 seconds for the water purifier to be half-burned when ignited on the outside, and approximately 180 seconds when ignited from inside. That is, it is thought that the internal combustion speed is higher because the internal ignition causes the generated heat to be accumulated and radiated instantly. It was observed that the water purifier damaged by fire caused by external ignition showed a uniform carbonization pattern and the carbide burned down at the bottom were gradually deposited. The water purifier damaged by internal ignition showed a relatively clear boundary of carbonized surface, which formed a V-pattern. The difference in the combustion patterns presents an objective base from which to determine where the fire started. By the time the purifier was half-burned by fire, the built-in fuse had not melted and the power supply protection device did not operate. In addition, as was found in the case of the fuse damaged by a general fire, carbonization occurred at the metal holder, and it is thought that this fact may be used as a basis from which to determine the cause of a fire.