• Korean Journal of Computational Design and Engineering
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• v.6 no.2
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• pp.111-124
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• 2001

In this paper, we propose rounding operations on shell meshes, which give a constant or variable radius of rounding directly to sharp edges on a shell mesh. The rolling-ball methods for freeform surface rounding are introduced to devise the algorithms for these operations. Our algorithms consists of three steps as follows: detecting sharp edges, generating a rolling-ball surface contacting with two face groups adjacent to the sharp edges, and then replacing the rounding area of the original mesh with the mesh generated on the rolling-ball surface. In addition, this paper shows their application to the area of stamping die design. These operations enable CAE engineers to directly change the meshes of stamping tools without modification of CAD models for dies and regeneration of their meshes.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.61-66
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• 1994

Tool condition monitoring is one of the most important aspects to improve productivity and quality and to achieve intelligent machining system. The tool state is classified into three groups as chipping, wear and fracture. In this study, wear of a ceramic cutting tool for hardened die material (SKD11) was investigated. Flank wear was occured more dominant than crarer wear. Therefore, to predict flank wear, the modeling of cutting force has been performed. The modeling of cutting force by an assumption that act the stress distribution on the tool face obtained through a numerical analysis. The relationships between the cutting force and the tool wear can be constructed by machining paraneters with cutting conditions. Experiments were performed under the various cutting conditions to ensure the validity of force models. The theoretical predictions of the flank wear is approximately in good agreement with experimental result.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.115-120
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• 2015

Deep drawing of cylindrical cups is one of the most fundamental and important processes in sheet metal forming. Circular cups are widely used in industrial fields such as automobile and electronic appliances. Some of these cups are formed by a one-stage process, others such as battery cases and beverage cans are made by a multi-stage process. In the current study the multi-stage deep drawing of aluminum sheet metal is examined. The process consists of two deep drawing operations followed by two ironing operations. The press die, which can be used for the four-stage forming process, was manufactured allowing punch and die components to be easily changed for various experiments. The rolling direction of both the sheet and the drawn cups was always positioned toward the horizontal x-direction on the die face to minimize experimental errors during the progressive forming. The dimensional accuracy of the cylindrical cups formed at each stage and the earing defect due to the anisotropy of sheet were investigated. The influence of anisotropy on the thickness distribution was also examined. Both the thickness and the outer diameter of the cups were measured and compared for each set of experimental conditions. It was found that the dimensional accuracy of cups rapidly improves by employing the ironing process and also by increasing the amount of ironing.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.2
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• pp.72-77
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• 2007

Abrasive wear between piston ring face and cylinder liner is an extremely unpredictable and hard-to-reproduce phenomenon that significantly decreases engine performance. Wear by abrasion are forms of wear caused by contact between a particle and solid material. Abrasive wear is the loss of material by the passage of hard particles over a surface. From the pin-on-disk test, particle dent test and scuffing test, abrasive wear characteristics of diesel engine cylinder liner-piston ring have been investigated. Pin-on-disk test results indicate that abrasive wear resistance is not simply related to the hardness of materials, but is influenced also by the microstructure, temperature, lubricity and micro- fracture properties. In particle dent test, dent resistance stress decreases with increasing temperature. From the scuffing test by using pin-on-disk tester, scuffing mechanisms for the soft coating and hard coating were proposed and experimentally confirmed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.5
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• pp.508-513
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• 2015

In this study, the effect of the helix angle and rake angle of a flat end-mill in the milling of titanium alloy was investigated. Tool shape parameters such as helix angle and rake angle affect the cutting force, cutting zone temperature, vibration, and chip flow mechanism, which in turn determine tool life, surface integrity, and dimensional accuracy of the milling process. To investigate the effect of the helix and rake angles, a certain range of parameters was selected, and three-dimensional tool models were generated for finite element analysis (FEA) for each case. The cutting force and pressure on the tool flank face and rake face were investigated by FEA. Further, several tool models were proposed for machining tests. The cutting force characteristics were investigated by the machining tests.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.476-481
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• 1998

It is generally known that in high speed work with more than 1000 m/min cutting speed, according to the work material phenomenon of tool wearing is increased due to the some produced neat and as a result this makes the cutting work impossible. In this study, the high speed cutting is possible because of the different cutting from the presently known fact. That is, most of generated heats influence on the quantity flowing in chip greatly. Therfore, this study aims at the behavior of cutting heat generated at high speed cutting. It makes clearly the euqntity of heat flowing in chip, work materal, tool, and inflowing ratio. The cutting mechanism varies by the changing of cutting depth, slant face and contact area through this study. And it is exammined that the influence of heat of all parts is greatly due to the change the contact length of clearance face. It is confirmed from the exp[eriment that the inflowing heat ratio influences the cutting speed greatly and the heat of clearance face can not be disregarded.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.1
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• pp.1-10
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• 2008

In this paper, we designed a facial feature(eyes, a moult and a nose) detection hardware based on the ICT transform which was developed for face detection earlier. Our design used a pipeline architecture for high throughput and it also tried to reduce memory size and memory access rate. The algerian and its hardware implementation were tested on the BioID database, which is a worldwide face detection test bed, and its facial feature detection rate was 100% both in software and hardware, assuming the face boundary was correctly detected. After synthesizing the hardware on Dongbu $0.18{\mu}m$ CMOS library, its die size was $376,821{\mu}m^2$ with the maximum operating clock 78MHz.

• Korean Journal of Computational Design and Engineering
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• v.9 no.4
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• pp.286-293
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• 2004

Recently, hot processing using the heat source like laser machining and RFS was developed and spreaded gradually. In order to generate tool-path for the proper hot tool, a new tool-path linking algorithm is needed because tool-path linking algorithm for machining can't be applied. In this paper, zigzag tool-path liking algorithm was proposed to generate tool-path automatically for RFS. The algorithm is composed of three steps: 1) Generating valid tool-path element, 2) Storing tool-path elements and creating sub-groups, 3) linking sub-groups. Using the proposed algorithm, CAD/CAM software for the tool-path generation of hot tool was developed. The proposed algorithm was applied and verified for Venus's face and die of cellular phone case.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.3
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• pp.64-73
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• 2005

This paper is concerned with the simulation-based parameter determination for the tool design in the stamping process of the complicated auto-body member. The CAE procedure of the stamping process is proposed so that troubles such as wrinkle, springback and excess metal be eliminated with changing parameters such as the blank size, the restraining force of the draw-bead and the embossing shape in the die face. The selected indicators of failure during forming are wrinkling. the amount of spring after unloading of the tool, the amount of excess metal developed .The proposed analysis scheme is applied to the tool and process parameter design for the front side member of a RV car. The simulation results show that the scheme can produce sound product from the viewpoint of thickness distribution, the contact condition between tools and the blank, the shape accuracy and so on.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.10a
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• pp.106-110
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• 2001

The ball-end milling process is widely used in the die/mold industries, and it is very suitable for the machining of free-form surfaces. However, this process is inherently inefficient process to compared with the end-milling or face milling process, since it relays upon the machining at the cutter/surface contact point. The machined part is the result of continuous point-to-point machining on the free-form surface. And cusps (or scallops) remain at the machined part along the cutter paths and they give the geometrical roughness of the workpiece. Thus, for the good geometrical roughness of the workpiece, it is required very tightly spaced cutter paths in this ball-endmilling process. However, with the tight cutter paths, the geometrical roughness of the workpiece is not regular on the workpiece since the cusp height is variable in the previously developed ISO-parametric or Cartesian machining methods. This paper suggests a method of tool path generation which makes the geometrical roughness of workpiece be constant through the machined surface. In this method, Ferguson Surface design Model is used and cusp height is derived from the instantaneous curvatures. And, to have constant cusp height, an increment of parameter u or v is estimated along the reference cutter path. In ball-end milling experiments, the cusp pattern was examined, and it was proved that the geometrical roughness could be regular by suggested tool path generation method.