• Journal of KIISE
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• v.43 no.5
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• pp.516-523
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• 2016

For old-age makeups, makeup artists first make a mold cast of an actor's face using plaster and then sculpt wrinkles in clay on the plaster mold. After finishing the clay sculpture, its negative plaster mold is fabricated and silicone skin patches are finally made for application to the actor's face. This process takes a few days and is tedious for actors and makeup artists. With recent advances in 3D printing and scanning technology, it is becoming easier to scan and fabricate 3D faces. This paper presents a new pipeline composed of facial scanning, interactive wrinkle modeling, and mold printing stages to easily and efficiently fabricate silicone masks for old-age makeups without the use of plaster and clay. An intuitive sketch interface based on a normal map is proposed for the creation of wrinkles in real time, even with a high-resolution face model. Then the geometry of the final wrinkles is reconstructed using a depth map and the negative mold of the wrinkled face is printed. We also show that the presented pipeline can fabricate a silicone mask more conveniently than the traditional one that consists of pouring silicone into the prepared negative mold and then overlapping the mold with the original positive one.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.174-181
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• 2018

This paper examines the structural behavior of 3D printed concrete specimens with focus on the bond between the layers. The tensile bond and flexural strengths were investigated experimentally and compared with those of specimens made by conventional mold casting. The test parameters were the time gap between printing layers and the reinforcement between vertical layers. The results showed the 3D printed specimens had voids between layers and confirmed the strength reduction due to printing time gap and the stress concentration caused by the voids. Most of the reduction in tensile bond strength between layers was due to the stress concentration at least up to certain printing time gap. Moreover, beyond a certain printing time gap (24hours), the additional reduction in tensile bond strength reached a level that could affect the structural behavior. The reinforcement between layers was helpful to increase the ductile behavior which is essential to prevent the sudden collapse of the structure. In addition, the reduction in flexural strength due to the stress concentration by the voids was observed and should be considered in the design of 3D printed wall structures against the lateral load.

• Korean Journal of Materials Research
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• v.28 no.11
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• pp.663-670
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• 2018

H13 tool steels are widely used as metallic mold materials due to their high hardness and thermal stability. Recently, many studies are undertaken to satisfy the demands for manufacturing the complex shape of the mold using a 3D printing technique. It is reported that the mechanical properties of 3D printed materials are lower than those of commercial forged alloys owing to micropores. In this study, we investigate the effect of microstructures and defects on mechanical properties in the 3D printed H13 tool steels. H13 tool steel is fabricated using a selective laser melting(SLM) process with a scan speed of 200 mm/s and a layer thickness of $25{\mu}m$. Microstructures are observed and porosities are measured by optical and scanning electron microscopy in the X-, Y-, and Z-directions with various the build heights. Tiny keyhole type pores are observed with a porosity of 0.4 %, which shows the lowest porosity in the center region. The measured Vickers hardness is around 550 HV and the yield and tensile strength are 1400 and 1700 MPa, respectively. The tensile properties are predicted using two empirical equations through the measured values of the Vickers hardness. The prediction of tensile strength has high accuracy with the experimental data of the 3D printed H13 tool steel. The effects of porosities and unmelted powders on mechanical properties are also elucidated by the metallic fractography analysis to understand tensile and fracture behavior.

• Journal of Fashion Business
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• v.21 no.5
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• pp.136-150
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• 2017

3D printing has grown tremendously as the most noteworthy new technology in the manufacturing industries. In addition, the rapid development of computer science technology with 3D printing has created a new paradigm called Fractal Geometry, or a new form of digital art. This study explores the formative characteristics of 3D printing jewelry based on presentation of fractal geometry by classification of 3D printing jewelry's morphological types that except for producible shape with traditional mold manufacturing methods. The results of the study are as follows. The morphological characteristics of 3D printed jewelry are divided into their constitutive shapes by the repetition of the unit. The organic shape determined by superposition or overlapping, the systematic shape by distortion caused by distortion, and the variation in scaling by scaling. The formative characteristics, which are drawn from a study on the shape expression of 3D printed jewelry design using fractal geometry, consist of continuity, geometrical characteristics, and exaggeration. Continuity creates a new and self-assigned new space through a recursive structure through a cyclic structure that is formed along a single directional basis. The geometry of the geometry forms a three-dimensional and constructive structure comprised of the same size and structure of the same sized unit under the mathematical order of the geometry of Fractal's geometry. Exaggeration demonstrates the informal beauty and the maximization of the shape by expanding the scaling or superposition of a unit, by scaling the scale or he distortion of the units.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.254-258
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• 2016

In this paper, a brain phantom for evaluating brain stroke localization is proposed. To evaluate brain stroke localization, a phantom imitating three-dimensional (3D) simulation environment is needed. Mold for the proposed phantom was printed by a 3D printer and the interior of the phantom consists of 5 different brain tissue materials. Each of the brain tissue materials has the conductivity and permittivity similar to those of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) standards for a frequency band from 0.5 to 2 GHz.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.6
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• pp.553-560
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• 2017

3D printing technology has been a great interest in human bio-interfaces and human-like robotics since they require arbitrary and adaptive manufacturing. This research mainly concerns the 3D fabrication of a packed biosensor using elastomeric sheets made of PDMS. It is essential to design the PDMS molding with 3D printing since, in the case of biosensors, it should not only produce a conformal shape depending on an arbitrary skin surface but also guarantee a uniform thickness distribution during solidification in the PDMS prepolymer solution. To satisfy the characteristics of the PDMS molding, such as flexibility in the de-molding and stiffness in the solidification processes, multi-materials have been selectively applied to the PDMS molding design, which has been validated with finite element analyses and compared with the 3D printed molding.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.1-12
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• 2023

In the current era of the global mobile smart device revolution, electronic devices are required in all spaces that people interact with. The establishment of the internet of things (IoT) among smart devices has been recognized as a crucial objective to advance towards creating a comfortable and sustainable future society. In-mold electronic (IME) processes have gained significant industrial significance due to their ability to utilize conventional high-volume methods, which involve printing functional inks on 2D substrates, thermoforming them into 3D shapes, and injection-molded, manufacturing low-cost, lightweight, and functional components or devices. In this article, we provide an overview of IME and its latest advances in application. We review biomimetic nanomaterials for constructing self-supporting biosensor electronic materials on the body, energy storage devices, self-powered devices, and bio-monitoring technology from the perspective of in-mold electronic devices. We anticipate that IME device technology will play a critical role in establishing a human-machine interface (HMI) by converging with the rapidly growing flexible printed electronics technology, which is an integral component of the fourth industrial revolution.

• Design Convergence Study
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• v.16 no.1
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• pp.97-109
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• 2017

Interest in the exterior design of buildings has increased in recent years. Demand for various architectural structures is increasing. However, domestic form liner and design are still limited. Thus, this research uses 3D printers to omit the existing mold production process. Use digital data to produce products economically using various materials. It can be hoped that extending the lifespan of the concrete structure will reduce the cost of saving costs. The purpose of this study is to utilize the 3D printers to develop the design of a suitable formative shape for the purposes of the concrete. In this study, 3D printed form enables the possibility that the actual application is practical. Consideration for the artistic design of the art line was proposed for the purpose of considering the use of concrete structures for concrete structures.

• Design & Manufacturing
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• v.16 no.3
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Composites Research
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• v.34 no.2
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• pp.136-142
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• 2021

3D printing technology has the advantage of easy to make various shapes of products without a mold. However, it has a problem such as mechanical properties vary greatly depending on materials and manufacturing conditions. Thus, the need for research of 3D printing technology on ways to reduce manufacturing cost compared to physical properties is increasing. In this study, a 3D printing thermoplastic structure was fabricated using short fiber carbon fiber reinforced nylon filaments. And a method of improving mechanical properties was proposed by reinforcing the outer surface using pultruded continuous fiber-type carbon fiber or glass fiber-reinforced thermosetting composite material. It was confirmed that the bending properties were improved according to the reinforcing position of the stiffener and the type of fiber in the stiffener.