• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.463-468
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• 2015

High vibration of a low pressure (LP) turbine casing caused safety problems and life at the facility it was housed in. The main focus of this study was the cause of the high vibration in a low pressure turbine casing with manufacturing defects by frequency response analysis, compared with the results of experiments. Therefore, excited accelerations were obtained from the LP casing fundamental, and frequency responses were analyzed. The measurement and the modal analysis showed that the natural frequency of the LP turbine casing was 61.26 Hz and the excited frequency of the turbine rotor was 60.25 Hz. The manufacturing defect caused a decrease in the casing natural frequency and resulted in the high vibration of the casing because it moved close to the resonant frequency.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.2
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• pp.364-367
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• 2001

We gamma-irradiated to natural casings from lamb and pork to improve sanitary quality and microbiological shelf stability of sausage stuffed in animal intestine-induced natural casing from lamb and pork. The microbial changes of irradiated casings and the microbial growth of the sausages with gamma-irradiated natural casings were observed. Population of total aerobic bacteria was decreased by gamma irradiation, dependent upon the irradiation dose. The number of microflora in lamb and pork casings was reduced by about 5.5 log cycle at 5 kGy. Population of total aerobic bacteria of sausages stuffed in non-irradiated lamb and pork casing was about 3.6 log CFU/g after just manufacture and was about 7 log after 10 day storage. However, population of total aerobic bacteria of sausages with 3 kGy-irradiated and 5 kGy-irradiated casings was 2.48 and 0.32 log in lamb, and 2.78 and 0.60 log in pork, respectively. Gamma irradiation to animal intestine- induced natural casings was effective and thus, can be used for enhancing shelf life of final products due to reduction of the number of contaminated microflora.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.9
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• pp.847-852
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• 2007

Design aspects of a bearing casing system of a power plant are mainly focused on the strength and weight of itself to have a more stable system. Since the rotor speed often passes through the critical speed region when the operation begins, the relation between the rotating frequency of the rotor and natural frequency of the casing is very important for a prevention of resonance. However, harmonic components above the rotating frequency have often been overlooked the design for the resonance avoidance. In this paper, it is revealed that resonance vibration is generated when the natural frequency of a bearing casing is close to the one of harmonics of basic rotating frequency(1x), and as a consequence, sensing qualify of seismoprobes attached to the bearing casing structure can be seriously damaged. In order to reduce the resonance vibration, some stiffeners are added to the casing structures. Significant reduction in the magnitude of vibration corresponding to 2x harmonic of basic rotating frequency is observed from both FE analysis and experiment.

• Geomechanics and Engineering
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• v.15 no.1
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• pp.677-686
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• 2018

Aimed at serious casing damage problem during the process of oilfield development by injecting water, based on seepage mechanics, fluid mechanics and the theory of rock mechanics, the multi-physics coupling theory was also taken into account, the mathematical model for production of petroleum with water flooding was established, and the method to solve the coupling model was presented by combination of Abaqus and Eclipse software. The Q9G3 block in Jibei oilfield was taken for instance, the well log data and geological survey data were employed to build the numerical model of Q9G3 block, the method established above was applied to simulate the evolution of seepage and stress. The production data was imported into the model to conduct the history match work of the model, and the fitting accuracy of the model was quite good. The main mechanism of casing damage of the block was analyzed, and some wells with probable casing damage problem were pointed out, the displacement of the well wall matched very well with testing data of the filed. Finally, according to the simulation results, some useful measures for preventing casing damage in Jibei oilfield was proposed.

• Journal of Power System Engineering
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• v.17 no.3
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• pp.23-27
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• 2013

In this research paper, we study on how to decrease the high vibration of turbine hood casings which are main facilities of power generation industry. Cause of Standard coal-fired power 500MW facilities turbine hoods' high vibration is that Natural frequency of hood casing designed in near domain frequency, when they are making hoods. We investigate to reduce high vibration at hood casing. We use FEM method to found how to avoid resonance, and test to confirm that our FEM result. We Finally attach minium mass plate at hood casing to avoid resonance and high vibration reduce lower $100{\mu}m$.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.34-39
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• 2014

In this study, the structural analysis and the modal analysis are conducted to investigate the stress level, the deformation characteristics and the natural modes of the casing of a planetary gear reducer for a 800kW grade pulverizer mill. The casing is subjected to the load, 2800 kN, from the lump coals in the pulverizing process. Because of the symmetry, the half portion of the reducer casing is modeled for the stress analysis. But the full model is used to find out the eigenvalues and natural modes for the modal analysis. The contact conditions are applied between the thrust pad bearing and the adjacent contacting parts. The results shows that the casing structure has the sufficient strength and stiffness to support the load under consideration. ANSYS version 15 is employed to perform the numerical study.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.1
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• pp.75-79
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• 2001

Quality changes in sausage stuffed into irradiated natural pork and lamb intestine were studied. Total aerobic bacteria of the sausage prepared with irradiated natural pork and lamb casing were significantly lower than those of nonirradiated casing and the $D_{10}$ value of those sausages were 1.71 and 1.58 kGy, respectively. The sausages in pork intestine vacuum-packaged and stored in a $4^{\circ}C$ refrigerator showed negligible change in the 2-thiobarbituric acid reactive substances (TBARS) value during storage except for 10-day when the TBARS value was higher than other storage days. Total working force for shear value of the sausages were lower with both irradiated casings but sensory evaluation showed no difference between treatments. As a results, the gamma irradiation was effective for sanitizing the natural pork and lamb casings, thereby preparing high quality sausages.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.498-503
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• 2009

This paper presents the vibration problem of the Engine Casing (E/C) "B" deck in the handymax vessel and describes a method to avoid resonance. The first ship of the series did not have any vibration issue on the "B" deck. However, resonance condition occurred when additional machine was installed to the following vessels. To understand the dynamic characteristics of the deck, the normal mode analysis and impact test have been performed. Within the normal operating range of the vessel, the $1^{st}$ natural frequency of the E/C "B" deck is close to the main engine's $6^{th}$ order. Based on these analysis, a reinforcement on the deck was suggested and it proved to be effective. Since actual impact test after the reinforcement also confirmed the resonance avoidance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.98-102
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• 2005

Most bearing casings are designed to focus on strength and weight of themselves because rotor speed passes through the critical speed when operation begins in large plants such as power plants. And It is treated importantly the relation between rotating frequency of the rotor and the natural frequency of casings to prevent resonance. But there is some cases that it is overlooked for harmonic components above rotating frequency. So we present experimentally a case that harmonic forces may make a resonance on casing fixing probes to measure vibration in a turbine-generator system and the vibration is generated when one component of harmonic forces excites the mode that the natural frequency of a certain bearing casing is close to one of harmonics of basic rotating frequency (1x).

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.384-389
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• 2011

The vibration of a LP turbine casing may cause the problems of power generation and the life of its facility. In this study, we carried out on-site measurements of a LP Turbine in order to find the cause of the vibration and conducted experimental and numerical modal analysis of the turbine with its support frame. The measurement and the modal analysis show that the natural frequency of the turbine becomes close to 60 Hz due to the subsidence of the support. The elimination of the subsidence by shimming between the turbine and the support frame gave rise to the reduction of the vibration of the LP turbine case.