• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3048-3057
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• 1996

Analysis model containing two inclined surface cracks on semi-infinite elastic body is established and analyzed on the basis of linear fracture mechanics to examine mutual interference of two surface cracks. Muskhelishvili's complex stress functions are introduced and a set of singular integral equations is obtained for a dislocation density function. The stress intensity factors at crack tip are obtained by using the Gerasoulis'method. When two surface cracks are parallel and have the same length, the values of $K_1$and $\Delta K_11$(variation of $K_11$) for crack 1 and crack 2 decrease by the mutual interference of two surface cracks as the distance between the two surface cracks shortens. The effect of mutual interference is remarkable in high friction coefficient. In case that two surface cracks are parallel, the values of $K_1$and $\Delta K_11$for crack 2 decrease as the length ratio ot crack 2 to crack 1 becomes small. As the crack inclination angle rises, the value of $K_1$ and the mutual interference of $K_1$for crack 2 increase and the value of$\Delta K_11$ for crack 1 becomes smaller than that for crack 2.

• Journal of Power System Engineering
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• v.7 no.3
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• pp.48-53
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• 2003

This paper deals with the control of a horizontally placed flexible rotor levitated by electromagnets in a multi-input/multi-output (MIMO) active magnetic bearing(AMB) system. AMB is a kind of novel high performance bearing which can suspend the rotor by magnetic force. Its contact-free manner between the rotor and stator results in it being able to operate under much higher speed than conventional rolling bearings with relatively low power losses, as well as being environmental-friendly technology for AMB system having no wear and no lubrication requirements. In this MIMO AMB system, the rotor is a complex mechanical system, it not only has rigid body characteristics such as translational and slope motion but also bends as a flexible body. Reduced order nominal model is computed by consideration of the first 3 mode shapes of rotor dynamics. Then, the $H_{\infty}$ control strategy is applied to get robust controller. Such robustness of the control system as the ability of disturbance rejection and modeling error is guaranteed by using $H_{\infty}$ control strategy. Simulation results show the validation of the designed control system and the modeling method to the rotor.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.7 no.4
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• pp.51-56
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• 2011

Steam generator is one of the main equipments that affect safety and long term operation in nuclear power plants. Fluid flows inside and outside of the steam generator tubes and induces vibration. To prevent the vibration the tubes are supported by AVB (anti vibration bar). When the steam generator tube contact to AVB, it is damaged by the accumulation of wear and corrosion. Therefore studies are required to determine the effects of the gap between the steam generator tube and AVB. In order to obtain the stress and the displacement distributions of the steam generator tube, three dimensional finite element analyses were performed by using the commercial program ANSYS. Using the calculated the stress and the displacement distributions, the static residual strength of the steam generator tube can be evaluated. The results show that the stress and displacement of the steam generator tube increase significantly compared with the results from a zero-gap model.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.239-242
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• 2004

We investigated the nanotopography impact on the post-chemical mechanical polishing (post-CMP) oxide thickness deviation(OTD) of ceria slurry with a surfactant. Not only the surfactant but also the slurry abrasive size influenced the nanotopography impact. The magnitude of the post-CMP OTD increased with adding the surfactant in the case of smaller abrasives, but it did not increase in the case of larger abrasives, while the magnitudes of the nanotopography heights are all similar. We created a one-dimensional numercal simulation of the nanotopography impact by taking account of the non-Prestonian behavior of the slurry, and good agreement with experiment results was obtained.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.7
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• pp.677-684
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• 2010

Backlashes of gears provide gears for good lubrication and for removal of the interference between teeth by the wear and manufacturing errors. The backlash is the strong nonlinear factor to gears. This study deals with nonlinear modeling of helical gears with backlash. Excitation of helical gears comes from torque variation, the tooth surface error, and the periodical change of mesh stiffness. To study the effect of torque fluctuation, equation of motion for the single degree of freedom torsional model of helical gears with the periodical change of mesh stiffness and the backlash was derived. The Newmark beta method and the Newton-Raphson method were used to obtain the nonlinear behaviors of mesh forces of helical gears. All excitation frequencies initially caused the tooth separation and single-sided impacts of the gear pair and eventually led to the normal tooth contact. However, some special excitation frequencies caused the single-sided impacts in the entire time as well as the initial time. Damping increase reduced the duration of single-sided impacts, and the backlash increase caused those in the entire time domain.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.355-362
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• 2021

Since coaxial magnetic gears use non-contact power transmission, friction, wear, noise, and heat generated in the power transmission process of existing mechanical gears can be minimized. Currently, research for application to various industries is being actively conducted, but among the characteristics of coaxial magnetic gears, the problem of rapidly decreasing torque density at a high gear ratio was discussed. This paper proposes a direction for multiple gear combination using low gear ratio coaxial magnetic gears with high torque density. In order to confirm the effectiveness of the method, the torque density was compared with a single high gear ratio model, and the combination and design direction of multiple coaxial magnetic gears were shown.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.3
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• pp.224-233
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• 2024

The patient was a 69-year-old male who had decreased VDO and overbite of the anterior teeth due to severe teeth wear. Complete mouth rehabilitation was planned to restore esthetics and function. Due to the presence of a subgingival finish line, poor fit of the margin of the temporary crown, and insufficient oral hygiene management, gingival overgrowth and bleeding occurred in many teeth, and inaccurate impressions were taken. After dividing each arch and taking partial impressions, a transfer coping was made using pattern resin on each working model die, and after being placed on the abutment teeth, a master cast was made through pick-up impression taking to produce prosthesis. In this case, the final prosthesis produced on the second master cast were fitted in terms of proximal contact, marginal fit, vertical occlusal dimension, facial appearance, esthetics, and occlusion. After complete mouth rehabilitation, the patient was satisfied with function and esthetic appearance.

• Journal of IKEEE
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• v.26 no.3
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• pp.488-493
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• 2022

In manufacturing sites, bearing fault in eletrically driven motors cause the entire system to shut down. Stopping the operation of this environment causes huge losses in time and money. The reason of this bearing defects can be various factors such as wear due to continuous contact of rotating elements, excessive load addition, and operating environment. In this paper, a motor driving environment is created which is similar to the domestic manufacturing sites. In addition, based on the established environment, we propose a dataset for bearing fault detection by collecting changes in vibration characteristics that vary depending on normal and defective conditions. The sensor used to collect the vibration characteristics is Microphone G.R.A.S. 40PH-10. We used various machine learning models to build a prototype bearing fault detection system trained on the proposed dataset. As the result, based on the deep neural network model, it shows high accuracy performance of 92.3% in the time domain and 98.3% in the frequency domain.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.8
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• pp.1035-1041
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• 2013

To evaluate the structural integrity and dynamic characteristic of the knuckle part of a KTX anti-roll bar, an experimental and a numerical approach were used in this study. In the experimental approach, the acceleration and strain data for the knuckle parts of the KTX and KTX-SANCHUN anti-roll bar were respectively measured to evaluate and compare its structural dynamic characteristics under the operating environments of the Honam line. In the numerical approach, the evaluation of its structural integrity was conducted using LS-DYNA 3D, and then, the reliability of the finite element model used was ensured by a comparative evaluation with the experiment. The numerical results showed that the stress and velocity field of the knuckle part composed of a layered structure of a thin steel plate and rubber were more moderate than those of the knuckle part made of only a thick steel block owing to the reduction of relative contact between the knuckle and the connecting rod. It was found that the knuckle part made of a thin steel plate and rubber was recommended as the best solution to improve its structural integrity resulting from the elastic behavior of the KTX anti-roll bar being enabled under a repeating external force.

• Journal of Industrial Convergence
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• v.1 no.1
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• pp.41-70
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• 2003

Many researches on brand equity have been focused in definition about it, factors of it, and the process of formation. Most of them have been used by voluntary production category, as is durable goods or nondurable goods. But this study, using the model is developed by Foote, Cone & Be1ding(FCB) Company, classified four fields, high-low involvement, rationality(rational or sensitive) involvement. The selected goods is a sensitive high involvement(casual wear). This study investigate the effects of brand equity and search the influences of brand equity formation according to factors of marketing mix. To this goals, this study kept a literature survey and a demonstrative research. In literature survey, there are several definitions of brand and brand equity. The research model is derived from selected factors of marketing mix and former study. This study used the regression analysis to verify effects from brand equity through the selected marketing mix. The research data is collected from the capital area. The focus of this study is effects of brand equity according to marketing mix. The followings are results and suggestions of this study. First, in the price factors, the affirmative effects are revealed the perceived quality and the brand awareness in a rational high involvement goods, the perceived quality and the brand associations in a sensitive high involvement goods, all factors of brand equity in a rational low involvement goods, and the perceived quality in a sensitive low involvement goods. As summary, the important characteristics is the price factors to consumers, and consumers recognize that a high price means a high quality. Second, in the store image factors, the affirmative effects are revealed all brand equity factors in a rational high involvement and a sensitive high-low involvement. A good store image incites more interest, contact, and visit from potential consumer. And such store offers more consumer satisfaction, simulates more active and positive conversation to consumers. Third, in advertising spending factors, the affirmative effects are revealed the brand awareness and associations in a rational high involvement and a sensitive high involvement, all brand equity factors in a rational low involvement and a sensitive low involvement. An advertisement increases not only a brand awareness but also strong brand associations. Forth, in price promotion factors, the affirmative effects are revealed the brand associations in a rational high involvement, the negative effects are revealed all brand equity in sensitive high involvement. According the result about the effects of brand royalty through the brand equity factors, a perceived quality and brand associations have positive effects to brand royalty in all factors. Consumers choice a deep perceived quality than other competitive brand. So, brand equity will increase according to a qualitative grade of a perceived brand by consumers. Brand associations represent a quality and a degree of involvement. In conclusion, brand associations and equity have a positive relation each other. According to the analysis results about a brand royalty of selected marketing mix factors, the affirmative effects are revealed the store image and price promotion factors in a rational high involvement, the price and store image in a sensitive high involvement, and the price and advertising spending in a rational low involvement. The results about the affect of selected marketing mix factors according to brand equity, are the perceived quality in a high involvement, and all brand equity factors in a low involvement. The affirmative effects about a store image are revealed all equity factors in high-low involvement. In advertising spending factors, the affirmative effects are revealed the brand awareness and associations in a high involvement goods, and the perceived quality and the brand awareness in a low involvement goods. In price promotion factors, the affirmative effects are revealed the brand awareness in a low involvement goods, and the negative effects are revealed the brand awareness in a high involvement goods. According to a degree of involvement, the results of a brand royalty through a brand equity factors are following. The affirmative effects are revealed the perceived quality and the brand royalty in a high involvement goods, and the brand awareness are revealed a negative effect. The affirmative effects are revealed the perceived Quality and the brand associations in a low involvement goods. So, in a high involvement goods, the brand royalty is built by strong brand associations, but, in a low involvement goods, the brand royalty is built also by a perceived Quality and a brand awareness. This study have some concept of limitation. So, this study presents a future direction of research. First, a future study has to have more deep analysis for this study analyzed through a limited marketing mix factors. Second, a future research has to get mutual effects about brand equity of marketing mix factors for this study has an individual marketing decision factors. Third, for the future, a brand equity needs a research about a several goods such as services, profit or nonprofit, industrial products, culture, and so on. Forth, the research have to diversify a various data for population.