• Kyungpook Mathematical Journal
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• v.48 no.4
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• pp.721-727
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• 2008

Let $W_{\alpha}$ be a weighted shift with positive weight sequence ${\alpha}=\{\alpha_i\}_{i=0}^{\infty}$. The semi-cubical hyponormality of $W_{\alpha}$ is introduced and some flatness properties of $W_{\alpha}$ are discussed in this note. In particular, it is proved that if ${\alpha}_n={\alpha}_{n+1}$ for some $n{\geq}1$, ${{\alpha}_{n+k}}={\alpha}_n$ for all $k{\geq}1$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.686-689
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• 2004

As the demands of X-Y linear motors increase, it becomes very important to measure flatness errors and to compensate them. In this study, in order to investigate flatness errors, a laser interferometer is used for measurement. To improve the measurement efficiency, a Union Jack method is adopted instead of a square method. The square method is frequently used because of its accuracy, but it requires many measurement points. In this study, the Union Jack method with Grey Theory is used. By using the Grey Theory, unmeasured data are predicted, and these are compared with results of the square method. The results show that the Union Jack method with Grey Theory is accurate enough to replace the square method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.05a
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• pp.74-79
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• 2004

The shape of cold rolled steel sheets is the degree of flatness, and the flatter, the better. Because undesirable strip shapes of cold rolled steel sheets can affect not only visible problem but also automatic working process in customer's lines, the requirement of the customers is more and more stringent. So we usually used the tension leveler to make high quality of strip flatness. For the improvement of the quality of strip flatness, this report developed three-dimensional FEM (Finite Element Method) simulation model, and analysis about the strain and stress distribution of strip in the tension leveling process.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.273-276
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• 2006

The focus of this study is on the enhancement of flatness for the shielded slot plate, one of main components of the MCFC stack. The shielded slot plate is to get curvature during manufacturing process since it is produced by forming operation from only one side of it. Therefore, a correction die is proposed to place just after the main die to apply unbending on the curved plate to get almost flat product. In the design for the correction die, four kinds of design factors are selected to study which factor is the most influencing one affecting the flatness of the plate. From the experimental results using Taguchi method, it has been revealed that the Young's modulus of urethane die is the most critical factor.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.363-367
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• 1999

New glass ceramics were investigated for the application as substrates to be used in hard disk devices. The glass system to precipitate lithium di-silicate was studied so as to optimize the composition to realize very high surface flatness. The addition of small amount of several metal oxides with high valences had very drastic effects on the microstructure, because they played a role of crystallization agents, and consequently it determined surface flatness even after the polishing process. The possible mechanism changes of crystal growth due to the addition of metal oxides were discussed in relation to the final micro-texture development. The glass ceramics with very high surface flatness(Ra=7.1 $\AA$) was obtained by the addition of the mixture of $P-2O_5 \;and \;MoO_3$ as crystallization agents.

• Design & Manufacturing
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• v.12 no.2
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• pp.11-15
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• 2018

In this study, we proposed three analysis methods to calculate the flatness of torque-angle sensors (TAS). We introduced two statistical and one geometrical methods in evaluating the precision of the flat plane in the axis direction for TAS. To verified the results, we fabricated TAS and a reference sample using a injection molding machine, mold, polyester as a raw material. We measured ($x_i$, $y_i$) position using 3D contact automated system and applied three analysis methods developed for TAS and a reference sample to see the feasibility. While each analysis method has its own pros and cons, the analysis using the shortest optimal distance was the most precise technique for the flatness evaluation of TAS components.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.04a
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• pp.48-51
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• 2009

Excessive wavy surfaces formed by a cold or hot-rolling process in a thin plate degrade the value of the plate significantly, which is called flatness problem in the industry. It is a result of post-buckling due to the residual stress caused by the rolling process. A unique difficulty of the problem as a buckling problem is that the buckling length is not given but has to be found. a new approach is developed to solve the flatness problem by extending a classic post-buckling analysis method based on the energy principle. The approach determines the buckling length and amplitude. The new solution approach can be used to determine the condition for the maximum rolling production that does not cause the flatness problem.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.23-28
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• 2006

The focus of this study is placed on the enhancement of flatness for the shielded slot plate, one of main components of the MCFC stack. The shielded slot plate is to get curvature during manufacturing process since it is produced by forming operation from only one side of it. Therefore, a correction die is proposed to place just after the main die to apply unbending on the curved plate to get almost flat product. In the design for the correction die, four kinds of design factors are selected to study which factor is the most influencing one affecting the flatness of the plate. From the experimental results using Taguchi method, it has been revealed that the Young's modulus of urethane die is the most critical factor.

• Design & Manufacturing
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• v.12 no.3
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• pp.31-35
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• 2018

In this paper, the method of improving the flatness and perpendicularity for a corner fixing bracket of the large display frame is studied through experiments. Three specimens were tested, one specimen not subjected to bending line before bending, and two specimens with a straight groove with 0.2 mm and 0.5 mm depth. Experimental results show that the flatness of bracket becomes worse with deeper depth. When there is no straight groove, the perpendicularity becomes worse. For the flatness correction, a restriking process was added. The twist of bracket was corrected by performing the restriking with a curvature larger than the twist amount in the direction opposite to the deformed direction. We also found that the perpendicularity is maintained regardless of the amount of curvature with the restriking process.

• Korean Journal of Applied Biomechanics
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• v.19 no.1
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• pp.59-66
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• 2009

The purpose of this study was to evaluate flatness of swing plane and determine swing plane type using 3-D swing plane analysis from young elite male golf players. This study also investigate the possibility of determination of swing plane using other kinematic parameters except flatness. As results, no correlations was found between flatness and handicap. Comparison of flatness between single plane and multiple plane swing group were performed and found a significant difference. The error range of flatness, 10cm, which was used for distinguish swing plane type was effective since significant differences were found at MB, EB, and EF. These differences were typical characteristics to classify two swing styles. Other kinematic parameters such as unit vector components of shaft and displacement of shaft end point also compared per event but found no significant differences. However, the moving patterns of these parameters during a golf swing showed such characteristics of each swing plane type well that these parameters could be used to determine swing style as an indirect barometers.