• Special Issue of the Society of Naval Architects of Korea
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• 2008.09a
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• pp.46-53
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• 2008

Recently, the synthetic material stern tube bush has been applied by ship owner's requirement because the synthetic material has a merit. That is to say, when stern tube seal is damaged and sea water comes into stern tube, it can work without problem because of water lubricating property. However, the material also has a demerit of temperature rise problem when some factors meets on synthetic material, for example, not sufficient lubrication oil supply and not proper shaft alignment and so on. As known in the world, the RAILKO bush is rampant for synthetic material by some ship owner because of the above mentioned reason. However, the bush has several accidents on large container vessel. Unfortunately or fortunately our yard has a chance to apply the RAILKO bush owing to requirement of specific ship owner. Therefore, it is much more required to approach the accurate shaft alignment analysis. In line with this reason, we had a shaft alignment calculation considering hull deformation and hull flexibility (hull stiffness). Also, in the calculation, we had considered dynamic condition which is reflected he propeller thrust forces and moments and oil film stiffness on the shaft alignment calculation. According to he shaft alignment calculation, bearing slope was applied on the tern tube bush and was measured. The RAILKO bush should be applied the running in procedure according to maker's recommendation for performing the oil film on the bush surface. Finally, the vessels were delivered successfully without any problem with AILKO bush as shown on his paper.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.46 no.3
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• pp.139-147
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• 2023

The metal bush assembling process is a process of inserting and compressing a metal bush that serves to reduce the occurrence of noise and stable compression in the rotating section. In the metal bush assembly process, the head diameter defect and placement defect of the metal bush occur due to metal bush omission, non-pressing, and poor press-fitting. Among these causes of defects, it is intended to prevent defects due to omission of the metal bush by using signals from sensors attached to the facility. In particular, a metal bush omission is predicted through various data mining techniques using left load cell value, right load cell value, current, and voltage as independent variables. In the case of metal bush omission defect, it is difficult to get defect data, resulting in data imbalance. Data imbalance refers to a case where there is a large difference in the number of data belonging to each class, which can be a problem when performing classification prediction. In order to solve the problem caused by data imbalance, oversampling and composite sampling techniques were applied in this study. In addition, simulated annealing was applied for optimization of parameters related to sampling and hyper-parameters of data mining techniques used for bush omission prediction. In this study, the metal bush omission was predicted using the actual data of M manufacturing company, and the classification performance was examined. All applied techniques showed excellent results, and in particular, the proposed methods, the method of mixing Random Forest and SA, and the method of mixing MLP and SA, showed better results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.635-640
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• 1996

A thermo-elastic system in the production machine has highly nonlinear dynamic characteristics. In general, the finite element method is utilized for accurate analysis. However, it requires large computing time. Thus, thermo-elastic systems are usuallymodeled as electric and fluid system using lumped para,eter. In this paper. we propose the bondgraph model and transient simulation methodology of thermo-elastic system in consideration of various boundary and joint contact conditions. Consequently, the proposed method ensures a possibility of its on-line compensation about undesirable phenomena by using real time estimate process and electronic cooling device for thermal appropriate behavior. Thermo-elastic model consisting of bush and shaft including contact condition is presented.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.219-223
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• 2005

In this work, a hybrid composite proceeding bearing (HCJB) composed of carbon/phenolic laminated composite bush and steel housing was designed for marine vessels because the composite proceeding bearing reduces the possibility of the seizure problem between the proceeding and bearing. The two components of bearing were assembled by interference fit joining method and a series of durability tests were conducted using the laboratory bench with the lubricants of SAE 30 oil, water, and sea water. That the HCJB was found reliable under the interference fitting loads and environmental temperature change.

• Journal of Mechanical Science and Technology
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• v.19 no.6
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• pp.1229-1242
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• 2005

When natural rubber is used for a long period of time, it becomes aged; it usually becomes hardened and loses its damping capability. This aging process affects not only the material property but also the (fatigue) life of natural rubber. In this paper the aging effects on the material property and the fatigue life were experimentally investigated. In addition, several fatigue life prediction equations for natural rubber were proposed. In order to investigate the aging effects on the material property, the load-stretch ratio curves were plotted from the results of the tensile test, the compression test and the simple shear test for virgin and heat-aged rubber specimens. Rubber specimens were heat-aged in an oven at a temperature ranging from $50^{\circ}C$ to $90^{\circ}C$ for a period ranging from 2 days to 16 days. In order to investigate the aging effects on the fatigue life, fatigue tests were conducted for differently heat-aged hourglass-shaped and simple shear specimens. Moreover, finite element simulations were conducted for the specimens to calculate physical quantities occurring in the specimens such as the maximum value of the effective stress, the strain energy density, the first invariant of the Cauchy-Green deformation tensor and the maximum principal nominal strain. Then, four fatigue life prediction equations based on one of the physical quantities could be obtained by fitting the equations to the test data. Finally, the fatigue life of a rubber bush used in an automobile was predicted by using the prediction equations, and it was compared with the test data of the bush to evaluate the reliability of those equations.