• 한국멀티미디어학회논문지
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• 제21권1호
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• pp.61-68
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• 2018

In this paper, we present an effective encryption algorithm for 3D printing models in the frequency domain of discrete cosine transform to prevent illegal copying, access in the secured storage and transmission. Facet data of 3D printing model is extracted to construct a three by three matrix that is then transformed to the frequency domain of discrete cosine transform. The proposed algorithm is based on encrypting the DC coefficients of matrixes of facets in the frequency domain of discrete cosine transform in order to generate the encrypted 3D printing model. Experimental results verified that the proposed algorithm is very effective for 3D printing models. The entire 3D printing model is altered after the encryption process. The proposed algorithm is provide a better method and more security than previous methods.

• 한국멀티미디어학회논문지
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• 제20권12호
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• pp.1951-1959
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• 2017

Due to the fact that 3D printing is applied to many areas of life, 3D printing models are often used illegally without any permission from the original providers. This paper presents a novel watermarking algorithm for the copyright protection and ownership identification for 3D printing based on the radius curvature of 3D triangle. 3D triangles are extracted and classified into groups based on radius curvature by the clustering algorithm, and then the mean radius curvature of each group will be computed for watermark embedding. The watermark data is embedded to the groups of 3D triangle by changing the mean radius curvature of each group. In each group, we select a 3D triangle which has the nearest radius curvature with the changed mean radius curvature. Finally, we change the vertices of the selected facet according to the changed radius curvature has been embedded watermark. In experiments, the distance error between the original 3D printing model and the watermarked 3D printing model is approximate zero, and the Bit Error Rate is also very low. From experimental results, we verify that the proposed algorithm is invisible and robustness with geometric attacks rotation, scaling and translation.

• 대한산업공학회지
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• 제41권3호
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• pp.253-258
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• 2015

The 3D printing is any of various processes for making a three dimensional object of almost any shape from a 3D model. Recently, a rapidly expanding hobbyist and home-use market has become established with the inauguration of the open-source RepRap and Fab@Home projects. However, this causes problems regarding copyright protection and usage of illegal 3D data. In this paper, we developed a 3D printing open-market system, which guarantees copyright protection using the remote 3D printing without direct distribution of 3D design data. Because most of the home-use 3D printers are FFF (Fused Filament Fabrication) based on NC code system, open-market system uses FFF 3D printers. Also, open-market system inspects the uploaded 3D model data, so the system can prevent distribution of illegal model data such as weapons, etc.

• 한국CDE학회논문집
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• 제21권3호
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• pp.215-223
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• 2016

The low price around 1000 USD makes consumer 3D printers as a new additive manufacturing platform for the personal manufacturing where consumers can make and sell their own products. To allow the consumers to design and manufacture their products, not only economic 3D printers but also supporting information systems for their design and manufacturing are essential. This study suggests an extended product data management (PDM) system that can support both the design and manufacturing of personal products with consumer 3D printing services. This extended PDM system helps consumer designers use advanced PDM technologies for their design and connected 3D printing services with Internet of Things (IoT) technology for realization of their products. As a result, the proposed system supports the consumer designers a seamless integrated product development and manufacturing environment supported by PDM and consumer 3D printing services.

• 한국의상디자인학회지
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• 제19권3호
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• pp.33-47
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• 2017

The purpose of this study is to provide fundamental data for the development of new course on 3D printing in the fashion design department. In order to investigate the perception of and educational needs in 3D printing, the data were collected from 266 students (female 68.8%, male 31.2%) majoring in fashion design aged 18-25 living in the capital area. The results of this survey showed that when investigating perceptions of 3D printing, it was found that 68.8% of answerers had indeed heard of 3D printing. Regarding the path they came to know about 3D printing, mass media such TV was the most frequent answer (54.6%). On the other hand, to the question asking about their intention to take the subject if given, approximately 71% said "Yes". Also, if a modeling class were given, the division that they wanted to explore most in the fashion industry was fashion jewelry. Finally, to the question asking interest in starting a business, 71.1% answered that they had interest. Out of those that answered that they had interest, when questioned about in which field they wanted to start a business, the most frequent answer was fashion online shopping mall. Finally, NCS-based 3D printing courses were suggested in the Fashion Design area. As 3D printing techniques are actively applied to the fashion industry overseas, creative education is needed through the integration of fashion and 3D printing technology by introducing 3D printing related programs in colleges.

• Journal of Computing Science and Engineering
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• 제11권4호
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• pp.152-159
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• 2017

Three-dimensional (3D) printing is applied to many areas of life, but 3D printing models are stolen by pirates and distributed without any permission from the original providers. Moreover, some special models and anti-weapon models in 3D printing must be secured from the unauthorized user. Therefore, 3D printing models must be encrypted before being stored and transmitted to ensure access and to prevent illegal copying. This paper presents a selective encryption algorithm for 3D printing models based on clustering and the frequency domain of discrete cosine transform. All facets are extracted from 3D printing model, divided into groups by the clustering algorithm, and all vertices of facets in each group are transformed to the frequency domain of a discrete cosine transform. The proposed algorithm is based on encrypting the selected coefficients in the frequency domain of discrete cosine transform to generate the encrypted 3D printing model. Experimental results verified that the proposed algorithm is very effective for 3D printing models. The entire 3D printing model is altered after the encryption process. The decrypting error is approximated to be zero. The proposed algorithm provides a better method and more security than previous methods.

• 공학교육연구
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• 제21권6호
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• pp.90-98
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• 2018

This paper proposes a framework of engineering education for product development processes based on product data management (PDM) software and 3D printing. The PDM software supports the product development process-oriented educational coursework, collaborative team projects and project-based learning environment. The 3D printing supports the prototyping step in the product development process and helps participants consider physical realization of their designs during the product design and development phases. The framework was implemented in an introductory course for engineering students to product design and development, and author found that it is important to support rich communication among participants including lecturers, teaching assistants and students to enhance the quality of education and to overcome the burden of learning various computer-aided tools and 3D printing techniques needed for the framework.

• 패션비즈니스
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• 제23권6호
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• pp.101-115
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• 2019

3D printing is attracting attention from all industries as it enables the development of personalized product design to meet consumer needs by establishing a mutual connection system between production, management and consumers. However, there are still limitations to applying them as apparel materials, and research on the recognition of 3D printing or the preference for fashion products is needed to actually commercialize 3D printing in the fashion industry. In this study on the development of various product designs using 3D printing technology in the fashion industry, an analysis of 255 questionnaires was conducted to determine the preferences and purchase intention trends of fashion product design using 3D printing for college students. Data analysis was performed with IBM SPSS Statistics (V.24). 'Fashion sensitive pursuit', 'Individuality & brand pursuit' and 'Functional convenience' was interested in fashion accessories using 3D printing technology and customized fashion apparel products using 3D printing. 'Functional Convenience-oriented' and 'Practical Purchasing-oriented' type showed that the functionality and durability of products made using 3D printing technology were important. And 'Individuality pursuit' type indicated that design and applied materials were important when producing products using 3D printing technology.

• 한국정밀공학회지
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• 제31권12호
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• pp.1085-1091
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• 2014

Recently, 3D printing has received increasing attention due to its boundless potentials. Because 3D printing starts from 3D geometry information, computer-aided design (CAD) is an essential technology to build 3D geometry data. These days, education of 3D CAD for engineering students has been changed from the theoretical lecture to practical design training using commercial CAD software. As a result, open-ended design projects have replaced the traditional theoretical examinations to evaluate students' outcomes. However, such design projects are not enough to evaluate students' outcomes because their results are expressed in two-dimensional ways. In this paper, applications of 3D printing in engineering design education are discussed by describing the procedure and outcomes of design projects. It was found that the use of 3D printing could improve students' outcomes by fabricating real physical models out of their designs.

• 패션비즈니스
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• 제22권4호
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• pp.93-105
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• 2018

Using FDM 3D printing, yarn shape and composition were modeled and 3D printed with PLA and TPU filaments currently used for apparel. Based on this, mechanical characteristics were measured to determine 3D printing yarn according to type of filaments in the 3D printed output and deformation and recovery characteristics due to differences in structure type. As a result of examining tensile and shear characteristics of PLA and TPU 3D printing compiles, TPU overall was measured with significantly lower stress than PLA. This is due to high elasticity of TPU's character, revealing that it has better flexibility than PLA. In addition, during deformation due to external forces, the more freedom between the head and foot parts of the loop, and the lower the force associated with each other, the more flexible it is. TPU revealed that it was easier to tension and recovery from tensile deformation than PLA, indicating potential for clothing materials using 3D printing. If high-molecular materials, such as PLA flexibility, it is likely to provide some flexibility through development of styles, including degree of freedom in modeling. Based on this, we provide basic data for developing 3D printing textures that can be satisfied with textile for apparel.