• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.58-63
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• 2000

The dynamics of spindle-bearing-workpiece system significantly affects the cutting condition and stability in milling process. The present paper investigates the chatter stability of milling process due to the change in the dynamics of spindle-bearing-workpiece systems. In particular, the present paper focuses on chatter stability due to the presence of gyroscopic effect. An eigenvalue problem approach to the stability of milling process is extensively used in this paper. To incorporate the rotational speed dependent gyroscopic effect, an iterative algorithm is proposed. A numerical example is provided for examining the chatter stability problem in the presence of gyroscopic effects.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.8-14
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• 2012

Two dimensional nesting is a common problem in industries such as the shipbuilding, automotive, clothing, shoe-making, and furniture industries, in which various parts are cut off from stock or packed in a flat space while minimizing waste or unoccupied space. Nesting is known as an NP-complete problem, which has a solution time proportional to the superpolynomial of the input size. It becomes practically impossible to find an optimal solution using algorithmic methods as the number of shapes to nest increases. Therefore, heuristic methods are commonly used to solve nesting problems. This paper presents an expert system that uses a heuristic search method based on an evaluation function for nesting problems, in which parts and stock are represented by pixels. The system is developed in CLIPS, an expert system shell, and is applied to four different kinds of example problems to verify its applicability in practical problems.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.144-146
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• 1994

We manufactured amorphous core for 1 KVA transformer by lap-step and one cut method, and measured the magnetic characteristics of the cores as a function of the number of ribbons per group, the number of group per set. the air gap and radius of core edge.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1483-1492
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• 2001

A robust optimization procedure is applied to determine the design of the laminated composite plates with buckling constraints. In order to investigate the variation effect to the whole performance of a structure, both design variables and system parameters are assumed as random variables about their nominal values. The robust optimization method has advantages that the mean value and the variation of the performance function are controlled simultaneously and the second order sensitivity information is not required. Considering the information of uncertainty, robust optima for the buckling load of the laminated composite plates with cut-out is obtained. The robustness of the structures is compared to that of the deterministic optimization using scaling factors.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.1
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• pp.62-69
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• 2008

A post-processing program based on the OOP(Object-Oriented Programming) concept has been developed for flow visualization of the flow analysis code(PowerCFD) using unstructured cell-centered method. User-friendly GUI(GTaphic User Interface) has been built on the base of MFC(Microsoft Foundation Class). The program is organized as modules by classes including those based on VTK(Visualization ToolKit)-library, and these classes are made to function through inheritance and cooperation which is an important and valuable OOP concept. The major functions of this post-processor program are introduced and demonstrated, which include mesh plot, contour plot, vector plot, surface plots, cut plot, clip plot, xy-plot and streamline plot as well as view manipulation (translation, rotation, scaling etc).

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.1003-1009
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• 2013

This paper presents a simple procedure to obtain the instantaneous cutting force constants needed to predict milling forces. Cutting force data measured in a series of slot milling tests were used to determine the cutting force constants at different feed rates. The values of the cutting force constants were determined directly at the tool rotation angle that maximized the uncut chip thickness. Then, the instantaneous cutting force constant was obtained as a function of the instantaneous uncut chip thickness. This approach can greatly enhance the accuracy of the mechanistic cutting force model for end milling. In addition, the influences of several cutting parameters on the cutting forces, such as the tool helix angle and axial depth of cut, were discussed.

• International Journal of Precision Engineering and Manufacturing
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• v.8 no.4
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• pp.10-15
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• 2007

Taguchi methods have been used for a long time to improve the product quality and process performance of a manufacturing system, Few researchers have applied this methodology in laser beam cutting (LBC) of sheet metals and found the considerable improvement in cut qualities. In all experimental investigations of LBC so far, the objective was to optimize the single quality characteristic at a time. In this paper the simultaneous optimization of multiple quality characteristics such as Kerf width and material removal rate (MRR) during pulsed Nd:YAG LBC of thin sheet of magnetic material (high Silicon-steel) has been presented using Taguchi's quality loss function. The results show the considerable improvement in multiple S/N ratio as compared to initial cutting condition. Also, the comparison of results from single and multi-objective optimization have been presented and it was found that the loss in quality is always possible shifting from single quality to multiple quality optimization.

• Journal of Life Science
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• v.9 no.1
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• pp.50-53
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• 1999

Effects of growth regulators and medium components were tested for shoot multiplication and callus growth from shoot explants of black locust. During shoot multiplication, callus growth at the cut end of shoot explants proceeded shoot development. The basal callus growth seemed to be a function of both mineral components and cytokinin supplemented in the medium. Maximum callus growth was induced by 0.5${\mu}$M BAP and the callus growth decreased as the level of BAP increased. Positive correlations were found between basal callus growth, and shoot multiplication and growth. Shoot multiplication was greatest on BSM medium (black locust shoot culture medium) supplemented with 1 $\mu$M BAP. With medium containing high nitrogen content, both shoot multiplication and growth were significantly enhanced. A new BRM medium was the most effective for rooting of black locust among three rooting media tested.

• Steel and Composite Structures
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• v.35 no.6
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• pp.753-763
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• 2020

In this article, the influence of fuzzified uncertain composite elastic properties on non-linear deformation behaviour of the composite structure is investigated under external mechanical loadings (uniform and sinusoidal distributed loading) including the different end boundaries. In this regard, the composite model has been derived considering the fuzzified elastic properties (through a triangular fuzzy function, α cut) and the large geometrical distortion (Green-Lagrange strain) in the framework of the higher-order mid-plane kinematics. The results are obtained using the fuzzified nonlinear finite element model via in-house developed computer code (MATLAB). Initially, the model accuracy has been established and explored later to show the dominating elastic parameter affect the deflection due to the inclusion of fuzzified properties by solving a set of new numerical examples.

• Journal of information and communication convergence engineering
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• v.9 no.2
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• pp.141-149
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• 2011

We consider the problem of assigning tasks to homogeneous nodes in the distributed system, so as to minimize the amount of communication, while balancing the processors' loads. This issue can be posed as the graph partitioning problem. Given an undirected graph G=(nodes, edges), where nodes represent task modules and edges represent communication, the goal is to divide n, the number of processors, as to balance the processors' loads, while minimizing the capacity of edges cut. Since these two optimization criteria conflict each other, one has to make a compromise between them according to the given task type. We propose a new cost function to evaluate static task assignments and a heuristic algorithm to solve the transformed problem, explicitly describing the tradeoff between the two goals. Simulation results show that our approach outperforms an existing representative approach for a variety of task and processing systems.