• Transactions of Materials Processing
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• v.11 no.4
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• pp.302-311
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• 2002

A generalized numerical approach based on the finite element method to analysis and design of hydroforming process is proposed in this paper. The special attention is focused on comparison of an implicit and an explicit finite element method widely used for hydroforming simulation. Furthermore, in order to meet the increasing real needs for prediction of forming limit, a ductile fracture criterion combined with finite element method is introduced and then applied to hydroforming process of an automobile lower m Consequently, the numerical analysis and design for hydroforming process presented here will facilitate the development and application of the tube hydrofoniung process to a new level.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.17 no.6
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• pp.97-103
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• 2008

In this paper, the Post Process for the manifold complex processing using CAD/CAM Software of two and a half Dimensions(2.5D) has been developed to maximize the application of the manifold manufacturing machine. Many companies are currently making use of high price systems to improve manufacturing process using the multi-axial complex manufacturing machine. In accordance with the requirements, the utilization of CAD/CAM Software for the manifold complex manufacturing machine is earnestly demanded. However, the experts who have experience in manifold manufacturing machine are insufficient. Consequently the outcomes of the Post Process for 2.5D CAD/CAM Systems have been dealt in order to be smoothly operated by those who have basic skills and be understood in process drawings. CNC program functions can be specially used as they are, when drawn up. The Post Process for the original point designation and transformation of coordinates has been developed and applied. The results gave proof of practical manufacturing outcomes.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.37-44
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• 2018

In laser material processing for high thermal conductivity, the thermal effect of laser beam shape was examined through computer simulations. In this paper, a circular beam with a focal radius of $500{\mu}m$, an elliptical beam with a major axis of 4 mm and a minor axis of 1 mm, and a rotating beam with a focal radius of $500{\mu}m$ and an angular velocity of 5 rad/sec were compared. Simulation results showed that there was no clear difference in the maximum temperature between the circular focus and the elliptical shape, but the heating and cooling rates were different. The simulation result for a laser beam rotating in a circular pattern with a radius of 5 mm showed an asymmetric temperature rise due to the combination of linear and rotational motion. At points where the rotational and linear speeds combined, the temperature gradually rose and reached the maximum temperature; whereas at points where the rotational and linear speeds were attenuated, the temperature tended to gradually decrease after reaching the maximum temperature. Based on the results of this study, the authors expect to be able to optimize laser material processing by designing patterns of laser beams.

• Transactions of Materials Processing
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• v.17 no.3
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• pp.155-160
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• 2008

We analyzed a sequence of multi-stage automatic cold forging processes composed of four axisymmetric processes followed by a non-axisymmetric process using rigid-plastic finite element based forging simulators. The forging sequence selected for an example involves a piercing process and a heading process accompanying folding or overlapping, which all make it difficult to simulate the processes. To reduce computational time and to enhance the solution reliability, only the non-symmetric process was analyzed by the three-dimensional approach after the axisymmetric processes were analyzed by the two-dimensional approach. It has been emphsized that this capability is very helpful in simulating the multi-stage automatic forging processes which are next to axisymmetric or involve several axisymmetric processes.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.184-200
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• 2020

Similarity searching is a basic issue in information processing because of the large size of formal contexts and their complicated derivation operators. Recently, some researchers have focused on knowledge reduction methods by using granular computing. In this process, suitable information granules are vital to characterizing the quantities of attributes and objects. To address this problem, a novel approach to obtain an entropy-weighted concept lattice with inclusion degree and similarity distance (ECLisd) has been proposed. The approach aims to compute the combined weights by merging the inclusion degree and entropy degree between two concepts. In addition, another method is utilized to measure the hierarchical distance by considering the different degrees of importance of each attribute. Finally, the rationality of the ECLisd is validated via a comparative analysis.

• Journal of Powder Materials
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• v.11 no.3
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• pp.233-241
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• 2004

In this study, bottom-up type powder processing and top-down type SPD (severe plastic deformation) approaches were combined in order to achieve both full density and grain refinement of Al-20 wt% Si powders without grain growth, which was considered as a bottle neck of the bottom-up method using the conventional powder metallurgy of compaction and sintering. ECAP (Equal channel angular pressing), one of the most promising method in SPD, was used for the powder consolidation. The powder ECAP processing with 1, 2, 4 and 8 passes was conducted for 10$0^{\circ}C$ and 20$0^{\circ}C$ It was found by microhardness, compression tests and micro-structure characterization that high mechanical strength could be achieved effectively as a result of the well bonded powder contact surface during ECAP process. The SPD processing of powders is a viable method to achieve both fully density and nanostructured materials.

• The Transactions of the Korea Information Processing Society
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• v.7 no.12
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• pp.3995-4003
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• 2000

This paper describes a method that extracts the region of car-licence plates in color images of private and commercial cars. To extract car-licence plates, we use the feature that car-licence plate regions have regular colors according to the kinds of cars. In this paper, we propose the method that combines H component of HSI color model and Q component of YIQ color model. To improve efficiency of the process, we cxplore lines ill a car image by a regular interval in a bottom-up style. As a result, the extraction rates by only H-component. only by Q- component. and by combined Hand Q, are 53.6%, 82.1%, and 94.6% respectively.

• Journal of Satellite, Information and Communications
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• v.6 no.1
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• pp.68-74
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• 2011

In this paper, we present the enhancement results such as availability and accuracy using the GPS L1 and Galileo E1 signal combination. To enhance the acquisition and tracking performance of signal processing in GNSS receiver. several tracking loops with integrator, discriminator, and loop filter module are applied. Also, this paper presents the performance comparison results between prototype receiver equipped with hardware board and software receiver. Also the tracking loop performance of real hardware receiver is verified by comparing with tracking accuracy, sensitivity occurred by the Spirent simulator. Especially, to process the Galileo E1 signal, it is used the a power early late type which is the typical type for DLL discriminator.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.165-175
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• 1996

the process of strip twisting is practiced for the manufacture of some commercial parts such as elements for tube type line mixers. A thin metal strip with rectangular cross section is twisted thru an angle greater than 180。. Initial geometry is altered in to a complex one with dimen-sional changes. In practice several tryouts are necessary to obtain required dimensional accu-racies. A simple analysis model is proposed to predict the dimensional changes forming torque and axial force.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.1
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• pp.224-241
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• 2015

Multiview plus depth (MVD) videos are widely used in free-viewpoint TV systems. The best-known technique to determine depth information is based on stereo vision. In this paper, we propose a novel local stereo matching algorithm which is radiometric invariant. The key idea is to use a combined matching cost of intensity and gradient based similarity measure. In addition, we realize an adaptive cost aggregation scheme by constructing an adaptive support window for each pixel, which can solve the boundary and low texture problems. In the disparity refinement process, we propose a four-step post-processing technique to handle outliers and occlusions. Moreover, we conduct stereo reconstruction tests to verify the performance of the algorithm more intuitively. Experimental results show that the proposed method is effective and robust against local radiometric distortion. It has an average error of 5.93% on the Middlebury benchmark and is compatible to the state-of-art local methods.