• Imaging Science in Dentistry
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• 제34권1호
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• pp.13-18
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• 2004

Purpose : This study was to evaluate the influence of slice thickness of computed tomography (CT) and rapid protyping (RP) type on the accuracy of 3-dimensional medical model. Materials and Methods: Transaxial CT data of human dry skull were taken from multi-detector spiral CT. Slice thickness were 1, 2, 3 and 4 mm respectively. Three-dimensional image model reconstruction using 3-D visualization medical software (V-works /sup TM/ 3.0) and RP model fabrications were followed. 2-RP models were 3D printing (Z402, Z Corp., Burlington, USA) and Stereolithographic Apparatus model. Linear measurements of anatomical landmarks on dry skull, 3-D image model, and 2-RP models were done and compared according to slice thickness and RP model type. Results: There were relative error percentage in absolute value of 0.97, 1.98,3.83 between linear measurements of dry skull and image models of 1, 2, 3 mm slice thickness respectively. There was relative error percentage in absolute value of 0.79 between linear measurements of dry skull and SLA model. There was relative error difference in absolute value of 2.52 between linear measurements of dry skull and 3D printing model. Conclusion: These results indicated that 3-dimensional image model of thin slice thickness and stereolithographic RP model showed relative high accuracy.

• 한국분말재료학회지
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• 제30권4호
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• pp.318-323
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• 2023

The thermoelectric effect, which converts waste heat into electricity, holds promise as a renewable energy technology. Recently, bismuth telluride (Bi2Te3)-based alloys are being recognized as important materials for practical applications in the temperature range from room temperature to 500 K. However, conventional sintering processes impose limitations on shape-changeable and tailorable Bi₂Te₃ materials. To overcome these issues, three-dimensional (3D) printing (additive manufacturing) is being adopted. Although some research results have been reported, relatively few studies on 3D printed thermoelectric materials are being carried out. In this study, we utilize extrusion 3D printing to manufacture n-type Bi_1.7Sb_0.3Te₃ (N-BST). The ink is produced without using organic binders, which could negatively influence its thermoelectric properties. Furthermore, we introduce graphene oxide (GO) at the crystal interface to enhance the electrical properties. The formed N-BST composites exhibit significantly improved electrical conductivity and a higher Seebeck coefficient as the GO content increases. Therefore, we propose that the combination of the extrusion 3D printing process (Direct Ink Writing, DIW) and the incorporation of GO into N-BST offers a convenient and effective approach for achieving higher thermoelectric efficiency.

• 한국정밀공학회지
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• 제31권12호
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• pp.1101-1106
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• 2014

Hybrid manufacturing technology has been advanced to overcome limitations due to traditional fabrication methods. To fabricate a micro/nano-scale structure, various manufacturing technologies such as lithography and etching were attempted. Since these manufacturing processes are limited by their materials, temperature and features, it is necessary to develop a new three-dimensional (3D) printing method. A novel nano-scale 3D printing system was developed consisting of the Nano-Particle Deposition System (NPDS) and the Focused Ion Beam (FIB) to overcome these limitations. By repeating deposition and machining processes, it was possible to fabricate micro/nano-scale 3D structures with various metals and ceramics. Since each process works in different chambers, a transfer process is required. In this research, nanoscale 3D printing system was briefly explained and an alignment algorithm for nano-scale 3D printing system was developed. Implementing the algorithm leads to an accepted error margin of 0.5% by compensating error in rotational, horizontal, and vertical axes.

• Current Applied Physics
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• 제18권11호
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• pp.1235-1239
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• 2018

We present a novel process to fabricate three-dimensional (3D) metallic patterns from 3D printed polymeric structures utilizing different hygroscopic swelling behavior of two different polymeric materials. 3D patterns are printed with two different polymers as cube shape. The surface of the 3D printed polymeric structures is plated with nickel by an electroless plating method. The nickel patterns on the surface of the 3D printed cube shape structure are formed by removing sacrificial layers using the difference in the rate of hygroscopic swelling between two printing polymer materials. The hygroscopic behavior on the interfaced structure was modeled with COMSOL Multiphysics. The surface and electrical properties of the fabricated three-dimensional patterns were analyzed and characterized.

• 대한기계학회논문집A
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• 제38권8호
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• pp.881-886
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• 2014

5 축 기반 3 차원 금속 프린팅에서는 파트형상에 overhang/undercut 형상이 존재하여도 tilting과 rotating의 2 축을 이용하여 파트형상의 조형 방향을 자유롭게 바꾸어 지지구조물(support structure) 형상피처의 추가 없이 3-D 적층(3DL: 3-D layering)이 가능하게 된다. 이를 위해서는 overhang/undercut의 형상근처에서 국부적으로 tilting과 rotating 정보에 맞는 조형 층 적층 정보를 제공하는 새로운 전처리기(preprocessor) 기능이 필요하게 된다. 본 논문에서는 overhang/undercut 과 같은 형상들을 자동으로 진단하고 검출하여 3 차원 layering 이 가능할 수 있도록 방사형 기울기 측정법(calculation of radial gradient: CRG)과 은유적 자동 분할 알고리듬(implicit auto-partitioning algorithm: IAP)을 통해 다중 적층 알고리듬(Multi-part Layering Algorithm: MPL)을 구현함을 제시하고 이를 실제 STL 형상파일에 적용하여 제시된 이론을 검증하고자 하였다.

• ETRI Journal
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• 제42권2호
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• pp.272-281
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• 2020

Three-dimensional (3D) selfie services, one of the major 3D printing services, print 3D models of an individual's face via scanning. However, most of these services require expensive full-color supporting 3D printers. The high cost of such printers poses a challenge in launching a variety of 3D printing application services. This paper presents a stencil-based 3D facial relief creation method employing a low-cost RGBD sensor and a 3D printer. Stencil-based 3D facial relief is an artwork in which some parts are holes, similar to that in a stencil, and other parts stand out, as in a relief. The proposed method creates a new type of relief by combining the existing stencil techniques and relief techniques. As a result, the 3D printed product resembles a two-colored object rather than a one-colored object even when a monochrome 3D printer is used. Unlike existing personalization-based 3D printing services, the proposed method enables the printing and delivery of products to customers in a short period of time. Experimental results reveal that, compared to existing 3D selfie products printed by monochrome 3D printers, our products have a higher degree of similarity and are more profitable.

• 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.

• 패션비즈니스
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• 제24권4호
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• pp.130-143
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• 2020

The development of three-dimensional (3D) printing technology is bringing new innovations to various fields such as health care, architecture, and fashion. 3D printing can be manufactured to suit the size of the consumer's body, modify the design to meet their tastes, and produce small quantities of various products. Therefore, 3D printing in the field of fashion has great potential. The purpose of this study was to investigate various application models of 3D printing for fashion design and analyze their characteristics after developing the fashion garment samples. First, the background of 3D printing was reviewed then, fashion designed by a 3D printing application was analyzed. As a result, four types of 3D printing applications were developed: object-attached, linkage, kinematics, and assembly. The object-attached type was the method of printing 3D material as an object in the intended shape and form and was attached to the garment by sewing. The linkage type referred to printing 3D material in small pieces of certain shapes that could be linked. The kinematics type was structures with hinges that could flex to fit the human body. The assembly type referred to developing 3D materials in female and male pieces such as nuts and bolts. By providing the advantages, disadvantages, trial-and-errors, and challenges of the 3D printing fashion design process, this study contributes to the effective applications and possibilities of future design.

• 한국정밀공학회지
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• 제34권4호
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• pp.293-298
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• 2017

In this study, we developed a 3D chocolate printer and studied the conditions needed for chocolate printing. Because chocolate is a mixture of cocoa mass, cocoa butter and sugar particles, its properties vary with temperature, and care is required in melting and extrusion. A chocolate supply unit is composed of a heating block and a syringe pump. It is integrated with a 3-axis linear robot. In order to be more accurate than the existing 3D chocolate printer is, the system was configured so that the printing line width became $430{\mu}m$. Printing performance was studied according to various parameters. The condition needed for printing lines with a stable width was discovered by the experimental design method and has been confirmed by a 2D line test. These 3D printing experiments showed that it was possible to build a 3D shape with an inclination angle of up to $45^{\circ}$ without support. Further, chocolate printing of a 3D shape has been successfully verified with the developed system.

• 한국분말재료학회지
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• 제28권3호
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• pp.208-215
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• 2021

Metal three-dimensional (3D) printing is an important emerging processing method in powder metallurgy. There are many successful applications of additive manufacturing. However, processing parameters such as laser power and scan speed must be manually optimized despite the development of artificial intelligence. Automatic calibration using information in an additive manufacturing database is desirable. In this study, 15 commercial pure titanium samples are processed under different conditions, and the 3D pore structures are characterized by X-ray tomography. These samples are easily classified into three categories, unmelted, well melted, or overmelted, depending on the laser energy density. Using more than 10,000 projected images for each category, convolutional neural networks are applied, and almost perfect classification of these samples is obtained. This result demonstrates that machine learning methods based on X-ray tomography can be helpful to automatically identify more suitable processing parameters.