• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.4
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• pp.485-490
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• 2003

RP(Rapid Prototyping) has been used in the various industrial applications. This paper presents the optimization techniques fur fabricated 3D model design using RP machine for the medical field. Once the original brain model data are obtained from 2D slices of MRI/CT machine, the data can be modeled as an optimal ellipse. The objective of this study includes optimization of fabrication time and surface roughness using the adaptive slicing method. It can reduce fabrication time without losing surface roughness quality by accumulating the slices with variable thickness. According to the parameter tuning and synthesis of its effect, more suitable parameter values can be obtained by enhanced 3D brain model fabrication. Therefore, accurate 3D brain model fabricated by RP machine can enable a surgeon to perform pre-operation. to make a decision for the operation sequence and to perceive the 3D positions in prototype, before delicate operation of actual surgery.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.7
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• pp.124-131
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• 2000

Rapid Prototyping(RP) models are no longer used only for design verification. Currently, parts built utilizing layer manufacturing technology can be employed as functional prototypes and as patterns or tools for different manufacturing processes such as vacuum casting, investment casting, injection molding, precise casting and sand casting. This trend of Rapid Prototyping application meets the requirement of concurrent engineering and its range covers a more spreaded area. The aim of this paper is saving the manufacturing lead time and cost of plastic parts having hollow space shapes used by prototype-car. Using rapid prototype patterns, made by the Selective Laser Sintering(SLS) technique, a new approach of manufacturing resin-based blow mold is discussed. It has a great potential fur making prototype-car parts with the batch size of under 200 parts, in case of rapid modification due to a subsequent design changes in developing stage. So, the process proposed in this research shows reduction of process time and manufacturing cost when compared with the conventional process such as a Zinc Alloy fur Stamping(ZAS) mold.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.4
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• pp.165-173
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• 2003

As the cycling time of new products have become more and more short in recent years, the demand for lowering the cost and reducing the production time becomes stronger. In order for the demand, the rapid prototyping and rapid tooling technology have been used. It has been widely known that RP technology has advantages with fabricating 3-D object having a complicated geometric shape. RP products, however, have a limitation with applying to the real die and mold because soft materials such as resin, paper and wax has been mostly used in RP technology. So in this paper, the RP products have been copied to semi-metallic soft tools using the mixture of metal fillers and epoxy resin. In order to evaluate the effect of the fillers on the characteristics of semi-metallic soft tools, three fillers are used including commercial aluminum powder, cast iron powder recycled by machining chips, and aluminum short fiber made by self-excited vibration technique. Besides, in the case of aluminum powder, the change of characteristics of semi-metallic soft tools is also tested according to the volume fraction of the powder.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.7 s.184
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• pp.101-107
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• 2006

Cold gas dynamic spray or cold spray is a novel manufacturing method for coatings. Cold spray is a high rate and direct material deposition process that utilizes the kinetic energy of particles sprayed at high velocity (300-1,200m/s). In this research, a technique to repair the damaged mold by cold spray deposition and mechanical machining was proposed. An aluminum 6061 mold with three-dimensional surface was fabricated, intentionally damaged and material-added by cold spray, and its original geometry was re-obtained successfully by Computer Numerical Control (CNC) machining. To investigate deformation of material caused by cold spray, deposition was conducted on thin aluminum plates ($100mm{\times}100mm{\times}3mm$). The average deformation of the plates was $205{\sim}290{\mu}m$ by Coordinate Measurement Machine (CMM). In addition, the cross section of deposited layer was analyzed by scanning electron microscopy (SEM). To compare variation of hardness, Vickers hardness was measured by micro-hardness tester.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.277-283
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• 2014

This paper presents the design, optimization and fabrication of a piezo driven micro-positioning stage constructed using a 3D-printer. 3D printing technology provides many advantageous aspects in comparison to traditional manufacturing techniques allowing more rapid prototyping freedom in design, etc. Micro-positioning stages have traditionally been made using metal materials namely aluminum. This paper investigates the possibility of fabricating stages using ABS material with a 3D printer. CAE simulations show that equivalent motion amplification can be achieved compared to a traditional aluminum fabricated stage while the maximum stress is 30 times less. This leads to the possibility of stages with higher magnification factors and less load on the driving piezo element. Experiment results agree with the simulation results. A micro-position stage was fabricated using a 3D printer with ABS material. The motion amplification is very linear and 50 nm stepping was demonstrated.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.1
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• pp.138-144
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• 2008

Micro-machining of a brittle material such as glass, silicon, etc., is important in micro fabrication. Particularly, micro-abrasive jet machining (${\mu}-AJM$) has become a useful technique for micro-machining of such materials. The ${\mu}-AJM$ process is mainly based on the erosion of a mask which protects brittle substrate against high velocity of micro-particle. Therefore, fabrication of an adequate mask is very important. Generally, for the fabrication of a mask in the ${\mu}-AJM$ process, a photomask based on the semi-conductor fabrication process was used. In this research a rapid mask fabrication technology has been developed for the ${\mu}-AJM$. By scanning the focused UV laser beam, a micro-mask pattern was fabricated directly without photolithography process and photomask. Two kinds of mask patterns were fabricated using SU-8 and photopolymer (Watershed 11110). Using fabricated mask patterns, abrasive-jet machining of Si wafer were conducted successfully.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.6
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• pp.98-104
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• 2010

Rapid Prototypes with internally colored objects are convenient by visualizing. A rapid prototyping method has been developed to fabricate mono-colored or multi-colored objects. In this work, a new process was proposed that can fabricate internally visible colored 3D objects in stereolithography parts. The process consists of projection stereolithography process using transparent photocurable resin for outer shapes and molten ink deposition process using molten solid ink for internal shapes. In molten ink deposition process, molten solid ink could be deposited uniformly in a designed pattern. To make molten solid ink uniform over a designed region, parametric study through a patterning solid ink was performed. By laminating resin and solid ink in sequence, the process can make colored 3D objects in StereoLithography(SL) parts. The practicality and effectiveness of the proposed process were verified through fabrication of colored basic 3D objects in SL parts.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.7
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• pp.799-804
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• 2012

Recently micro-nano structures has widely been reported to improve the performance of waterproof, heat isolation, sound and light absorption in various fields of electric devices such as mobiles, battery, display and solar panels. A lot of micro-sized holes on the surface of thin film provide excellent sound, or heat, or light transmission efficiency more than solid film and simultaneously nano-sized protrusions around micro hole increase the hydrophobicity of the surface of thin film because of lotus leaf effects as generally known previously. In this paper new rapid fabrication process with 355 nm UV laser ablation was proposed to get micro-nano structures on the surface of thin film, which have only been observed at higher laser fluence. Developed thin micro-nano structured film was also investigated the hydrophobic property by measuring the contact angle and demonstrated the possibility to apply to water droplet separation.

• Laser Solutions
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• v.11 no.2
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• pp.26-32
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• 2008

Micro lens array (MLA) is widely used in information technology (IT) industry fields, for examples such as a projection display, an optical power regulator, a micro mass spectrometer and for medical appliances. Recently, MLA have been fabricated and developed by using a reflow method, micro etching, electroplating, micromachining and laser local heating. Laser local thermal-expansion (LLTE) technology demonstrates the formation of microdots on the surface of polymer substrate, in this paper. We have also investigated the new direct fabrication method of placing the MLA on the surface of a SU-8 photoresist layer. We have obtained the 3D shape of the micro lens processed by UV laser irradiation and have experimentally verified the optimal process conditions.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.119-125
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• 2012

It is not an overstatement to say that the functions of the products change and the results determine the size and weight of the product. It took a long time to develop the small size everyday tools. One of the ways to shorten the development time was the emergence of vacuum moulds that decreased the design process significantly. In other words, the manufacturing of the product may be limited by the size and shape, but the replication of a simple structure is possible within a few hours. This study aims to review and suggest the design development through vacuum moulds as an area to realize the future additional values to the economic growth under the rapidly changing industry structures as well as securing the weaknesses of the industry structures through the productivity and competitiveness of the corporations.