• Journal of Drive and Control
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• v.21 no.1
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• pp.8-15
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• 2024

This thesis investigates the jetting characteristics of an aerosol jet printing (AJP) process as a function of design and operating conditions. The governing equations of the AJP system are derived for experimentation and analysis. To understand the characteristics of the AJP system, it analyzes the jetting characteristics as a function of the flow rate of the carrier gas and the sheath gas, and the variation of the linewidth with the nozzle exit size based on particle tracking. The thesis focuses on computational fluid dynamics (CFD), which is a computer simulation. The particle tracking results obtained by CFD were analyzed using MATLAB. CFD analytical models can be analyzed in environments with different conditions and consider more specific situations than mathematical computational models. The validity of the CFD analysis is shown by comparing the experimental results with the CFD analysis.

• Journal of Drive and Control
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• v.21 no.2
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• pp.8-14
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• 2024

This paper investigates the jetting characteristics of an aerosol jet printing (AJP) process as a function of design and operating conditions. The governing equations of the AJP system are derived for experimentation and analysis. To understand the characteristics of the AJP system, this thesis analyzes the jetting characteristics as a function of the flow rate of the carrier gas and the sheath gas, and the variation of the linewidth with the nozzle exit size based on particle tracking. This thesis focuses on computational fluid dynamics (CFD), which is a computer simulation. The particle tracking results obtained by CFD were analyzed using MATLAB. CFD analytical models can be analyzed in environments with different conditions and consider more specific situations than mathematical computational models. The validity of the CFD analysis is shown by comparing the experimental results with the CFD analysis.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.2
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• pp.263-272
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• 2013

Printed electronics creates electrically functional devices by printing on variety of substrates. Printing typically uses common printing equipment or other low-cost equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography and inkjet. Compared to conventional manufacturing of microelectronics, printed electronics is characterized by simpler and more cost-effective fabrication of high and low volume products. Now there is huge effort towards printing many other more functional components, from displays to transistors to photovoltaic cells, using the full range of printing technologies - from inkjet to roll to roll analogue print techniques. The market for printed electronics will rise from $1.99 billion in 2010 to $55.10 billion in 2020. In 2030, this industry could be $300 billion - larger than the silicon semiconductor industry - from lighting to displays[8].

• Journal of the Korea Fashion and Costume Design Association
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• v.14 no.3
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• pp.1-10
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• 2012

This study has purpose to understanding recent trends and image effect of textile in fashion by looking to dyeing technique and aesthetics of diffusing image pattern. Further the study will hope to provide basic data for fashion and textile designer fashion. The methods of this study are academic literatures as well as practical study through case studies about actual works. Dyeing techniques and aesthetics of diffusing image pattern since 2000 fashion collection and their results are as follows. First, Dyeing techniques of diffusing image pattern are wet-dyeing and printing. There are plangi dyeing, salt dyeing, alcohol dyeing and ikat dyeing in the wet-dyeing and spray dyeing, discharge dyeing in the printing. There are tie-dyeing, rumpling-dyeing and plank-dyeing in the plangi. Second, Forming of the diffusing image pattern are due to uneven seeping and the contingency of a chemical reaction by reducing the pressure and intensity. Third, Aesthetics of diffusing image pattern are extracted purity missing childhood, fantasy escaping facts of the situation and abstraction representing informal world from formative characteristics of diffusing image pattern.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.134-139
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• 2015

PolyJet technology is an additive manufacturing (AM) technology commonly used for modeling, prototyping, and production applications. It is one of the techniques used for 3D printing. The PolyJet technique is a process that joins materials to fabricate a product from 3D CAD data in a layer-by-layer manner. The orientation of a layer can affect the mechanical properties of the product manufactured by the PolyJet technique because of its anisotropy. In this paper, tensile and shearing tests of specimens were developed with the PolyJet technique in order to study the mechanical properties according to the orientation of a layer. The mechanical properties of the specimens were determined on the basis of true stress-strain curves from tensile and shearing tests. In addition, the tensile and shearing tests were simulated under the same conditions as those of experiment, and the experiment and simulated results were compared. Through this study, the fracture criteria could be established.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.40-43
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• 2004

Stamps for microcontact processing are fabricated by casting elastomer such as PDMS on a master with a negative of the desired pattern. After curing, the PDMS stamp is peeled away from the master and exposed to a solution of ink and then dried. Transfer of the ink from the PDMS stamp to the substrate occurs during a brief contact between stamp and substrate. Generally, negative-tone masters, which are used for making positive-tone PDMS stamps, are fabricated by using photolithographic technique. The shortcomings of photolithography are a relative high-cost process and require extensive processing time and heavy capital investment to build and maintain the fabrication facilities. The goal of this study is to fabricate a negative-tone master by using Nano-indenter based patterning technique. Various sizes of V-grooves and U-groove were fabricated by using the combination of nanoscratch and HF isotropic etching technique. An achieved negative-tone structure was used as a master in the PDMS replica molding process to fabricate a positive-tone PDMS stamp.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.270-276
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• 2020

3D printing is an additive manufacturing technology that can produce complex shapes in a single process for a range of materials, such as polymers, ceramics, and metals. Recent 3D printing technology has developed to a level that enables the mass-production through an improvement of the printing speed and the continuous development of applicable materials. In this study, 3D printing technology using a laser was applied to manufacture a heat exchanger for an air compressor in a railway vehicle. First, the optimal design of the heat exchanger was carried out by focusing on weight reduction and compactness as a shape suitable for 3D printing. Based on the design derived, heat exchanger prototypes were made of AlSi10Mg alloy material by applying the SLM technique. Moreover, the manufactured prototypes were attached to an existing air compressor, and the heat exchange performance of the compressed air was tested. The test results of the 3D printed prototypes showed a heat exchange performance of approximately 80% and 85% at low and high-pressure, respectively, compared to the existing heat exchanger. From the 𝓔-NTU method results with an external cooling air condition similar to that of the existing heat exchanger, the calculated heat transfer amount of 3D printed parts showed similar performance compared to the existing heat exchanger. As a result, the 3D printed heat exchanger is lightweight with good performance.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.221-228
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• 2017

This paper aimed to find out the eco-friendly approach enabling to directly print patterns and dye colors on fabrics using leaves of plants. In the research process, I found out the 'eco-printing' which could effectively express unique colors and patterns of plants. While eco-printing can design the patterns and colors of plants in nature using the leaves of plant(Eucalyptus), it is difficult to implement because it is not systematically and academically investigated including the dictionary definition in Korea until now. Thus, I tried to define the eco-printing and natural dyeing using leaves or flowers of plants enabling to get natural patterns and colors and do the experimental research and production using the leaves of Eucalyptus. The leaves of Eucalyptus were arranged on a wool scarf and a silk scarf, tied and applied pressure to them and made pigments penetrate into fabrics by heating or steaming them. This approach is to directly print the patterns using the shapes of plants on fabrics unlike the existing approaches dyeing by extracting dyeing solution from natural materials. Furthermore, the change of colors was attempted by using the color fixers. In accordance with the results of this experimental research, the scarf design differentiated from the existing products could be acquired. It was identified that eco-printing could induce the color variables depending on the conditions of each material and environment. For improving the color variables, various kinds of fabrics and divers kinds of materials which can be easily acquired in a daily life will be investigated and compared. Furthermore, it is expected that the experimental research and production techniques on eco-printing be utilized when starting natural dyeing and the scope of natural dyeing be more expanded.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.200-207
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• 2017

3D printing is making a huge difference to existing industries and is beginning to be applied in the field of construction. 3D printing construction differs from existing construction techniques. Therefore, new construction processes need to be developed. In particular, the accurate construction duration is linked directly to a successful project. A method for estimating the construction duration for 3D printing construction is necessary. In this study, a 3D printing construction process and duration estimation method were derived to prepare for the future introduction of 3D printing in construction. The scope of the study was assumed to be 3D printing equipment capable of pouring concrete, and limited to a frame structure construction. The developed construction period estimation method was applied to the virtual test model. As a result of applying the test model, the construction duration was shortened by approximately 50% compared to the existing construction technique. The method of estimating the construction period developed in this study can be applied to 3D printing constructions in the future and help establish a business plan.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.29 no.2
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• pp.54-60
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• 2019

Recently, various composite materials for additive manufacturing are interested to expand the application field of 3D printing. 3D printing technique was mainly developed using polymer, and ceramic materials for 3D printing are still in the early stage of research due to the requirement of high solid content and post treatment process. In this study, silica particles with various diameters were surface treated with silane coupling agent, and synthesized as silica composite with photopolymer to apply DLP 3D printing process. DLP is an additive manufacturing technology, which has high accuracy and applicability of various composite materials. The rheological behavior of silica composite was analyzed with various solid contents. After DLP 3D printing was performed using silica composites, the printing accuracy of the 3D printed specimen was less than about 3 % to compare with digital data and he bending strength was 34.3 MPa at the solid content of 80 wt%.