• 한국재료학회지
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• 제23권10호
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• pp.586-591
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• 2013

The printing of nanomaterials onto certain substrates is one of the key technologies behind high-speed interconnection and high-performance electronic devices. For the printing of next-generation electronic devices, a printing process which can be applied to a flexible substrate is needed. A printing process on a flexible substrate requires a lowtemperature, non-vacuum process due to the physical properties of the substrate. In this study, we obtained well-ordered Ag nanowires using modified gravure printing techniques. Ag nanowires are synthesized by a silver nitrate ($AgNO_3$) reduction process in an ethylene glycol solution. Ag nanowires were well aligned by hydrodynamic force on a micro-engraved Si substrate. With the three-dimensional structure of polydimethylsiloxane (PDMS), which has an inverse morphology relative to the micro-engraved Si substrate, the sub-micron alignment of Ag nanowires is possible. This technique can solve the performance problems associated with conventional organic materials. Also, given that this technique enables large-area printing, it has great applicability not only as a next-generation printing technology but also in a range of other fields.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.125-130
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• 2021

Scaffold is used to produce bio sensor. Scaffold is required high dimensional accuracy. 3D printer is used to manufacture scaffold. 3D printer can't detect defect during printing. Defect detection is very important in scaffold printing. Real-time defect detection is very necessary on industry. In this paper, we proposed the method for real-time scaffold defect detection. Real-time defect detection model is produced using CNN(Convolution Neural Network) algorithm. Performance of the proposed model has been verified through evaluation. Real-time defect detection system are manufactured on hardware. Experiments were conducted to detect scaffold defects in real-time. As result of verification, the defect detection system detected scaffold defect well in real-time.

• Advances in concrete construction
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• 제11권2호
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• pp.141-149
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• 2021

This study is a basic research for evaluating the buildability of cementitious materials for three-dimensional (3D) printing. In the cement paste step, the thixotropy behavior according to the resting time, which represents the time interval between each layer, was analyzed. In addition, the relationship between the thixotropy behavior and 3D concrete printing buildability was derived by proposing a measurement method that simulates the 3D concrete printing buildup process. The analysis of the tendency of the thixotropy behavior according to the resting time revealed that the area of the hysteresis loop (AHyst) showed a tendency to increase and then converge as the resting time increased, which means hysteresis loop approach critical resting time for sufficient buildability. In the thixotropy behavior analysis that simulates the 3D concrete printing buildup process, the buildup ratio, which is the recovery rate of the shear stress, showed a tendency to increase and then converge as the resting time increased, which are similar results like hysteresis loop. It was concluded that AHyst and the buildup ratio can be used as parameters for determining the resting time, and they have close relationships with 3D concrete printing buildability.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2017년도 춘계공동학술대회
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• pp.108-108
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• 2017

In this study, biocomposite filaments with agricultural by-products can be used in extrusion-based 3D (Three-dimensional) printing. Extrusion-based 3D printing stands as a promising technique owing to its versatility. We hypothesized that bio-filament composite consisted of something derived from agricultural by-products could be used as 3D printing materials that could overcome the drawbacks of PCL (poly-caprolactone). Bio-filament mixed with PCL and agricultural by-products was defined as r-PCL in this study. In order to find it out the optimal mixing ratio of filaments, we had investigated PCL, r-PCL 10%, r-PCL 20%, r-PCL 50% separately. The morphological and chemical characteristics of the filaments were analyzed by FE-SEM (Field emission scanning electron microscope) and EDX (Energy-dispersive X-Ray spectroscopy), and the mechanical properties were evaluated by stress-strain curve, water contact angle, and cytotoxicity analysis. Results of this study have been shown as a promising way to produce eco-friendly bio-filaments composite for FDM (Fused deposition modeling) method based 3D printing technology. Thus, we could establish biomimetic scaffolds based on bio-printer filaments mixed with agricultural by-product.

• 한국HCI학회논문지
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• 제11권1호
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• pp.47-55
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• 2016

삼차원 프린팅(이하 3D프린팅)은 현대인들에게 새로움과 흥미를 줄 뿐 아니라 새로운 산업혁명을 예고할 정도로 각광받는 기술이다. 또한 다양한 3D프린팅 서비스 플랫폼의 출현으로 개인들도 3D프린팅으로 디자인한 제품을 쉽게 소유할 수 있게 되었다. 그러나 3D프린팅이 대중화되는 시대, 3D프린팅으로 누구나 원하는 제품을 디자인해서 만들 수 있는 신제조시대가 오기까지는 아직 고려할 문제들이 많아 보인다. 예를 들어, 과연 현존하는 3D프린팅 서비스들이 기존에 기계나 사람이 제작하던 제품을 3D프린팅으로도 만들 수 있다는 것 이상을 보여줄 수 있는지, 현존하는 대다수의 3D프린팅 서비스 플랫폼들처럼 넓은 범위의 제품군을 판매하는 것이 소비자들에게 어떤 의미를 제공할 것인지 등에 대한 충분한 고려와 연구가 필요하다. 이런 맥락에서 시작한 본 연구는 소비자들로 하여금 제품군의 범위가 넓은 3D프린팅 온라인 서비스 플랫폼과 상대적으로 좁은 서비스를 직접 경험해보게 한 후, 구매희망 사이트, 디자인의 다양성, 디자인 만족도, 지각된 기술력, 지각된 구매만족, 지각된 애프터서비스(A/S)를 비교하고 선택형 질문과 서술형 질문에 응답하게 함으로써 향후 3D프린팅 서비스가 나아가야할 방향이 무엇인지에 대한 통찰을 얻고자 했다. 결과적으로 제품군의 범위가 넓은 서비스(예: Shapeways)에 대한 소비자들의 선호가 좁은 서비스(예: Digital Forming)에 대한 선호보다 전반적으로 강함을 관찰하였고, 디자인의 다양성과 원하는 디자인의 구현 가능성이 3D프린팅 서비스가 고려해야할 가장 중요한 요소임을 확인할 수 있었다. 더하여 향후 경쟁력 있는 3D프린팅 서비스가 되기 위해 다양한 분야의 디자이너풀을 확보를 통한 디자인 컨설팅을 진행, 초보자들도 쉽게 디자인할 수 있는 웹기반 소프트웨어 제공, 온-오프라인 매장 병행운영에 대해 논의하였다.

• 센서학회지
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• 제28권2호
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• pp.113-116
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• 2019

A three-dimensional porous structure was fabricated by pattern transfer printing for applications of electrodes in gas sensors. To form replica patterns, solutions were mixed with acetone, toluene, heptane, and poly(methyl methacrylate). These replica patterns can also be formed on substrates such as polyimide, polydimethylsiloxane, and silicon. The wide range of line widths from 1 to $5{\mu}m$ was derived from the surface grating patterns of master substrates. The cross-bar pattern with 40 layers showed a thickness of 600 nm. The area of platinum transferred patterns with different line widths was enhanced to $20{\times}25mm$, which is applicable to various electrode patterns of gas sensors.

• 한국기계가공학회지
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• 제16권3호
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• pp.1-8
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• 2017

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by a computer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along the Z-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types of printing paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists can be produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it is necessary to remove these twists during process planning. In this research, An algorithm is presented to remove twists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offset loops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop to decide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm is verified to use in tool path generation for 3D printing.

• 한국정밀공학회지
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• 제31권12호
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• pp.1067-1076
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• 2014

To date, biomedical application of three-dimensional (3D) printing technology remains one of the most important research topics and business targets. A wide range of approaches have been attempted using various 3D printing systems with general materials and specific biomaterials. In this review, we provide a brief overview of the biomedical applications using 3D printing techniques, such as surgical tool, medical device, prosthesis, and tissue engineering scaffold. Compared to the other applications of 3D printed products, the scaffold fabrication should be performed with careful selection of bio-functional materials. In particular, we describe how the biomaterials can be processed into 3D printed scaffold and applied to tissue engineering area.

• Restorative Dentistry and Endodontics
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• 제44권3호
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• pp.29.1-29.7
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• 2019

Endodontic microsurgery is defined as the treatment performed on the root apices of an infected tooth, which was unresolved with conventional root canal therapy. Recently, the advanced technology in 3-dimensional model reconstruction based on computed tomography such as cone beam computed tomography has opened a new avenue in application of personalized, accurate diagnosis and has been increasingly used in the field of dentistry. Nevertheless, direct intra-oral localization of root apex based on the 3-dimensional information is extremely difficult and significant amount of bone removal is inevitable when freehand surgical procedure was employed. Moreover, gingival flap and alveolar bone fenestration are usually required, which leads to prolonged time of surgery, thereby increasing the chance of trauma as well as the risk of infection. The purpose of this case report is to present endodontic microsurgery using the guide template that can accurately target the position of apex for the treatment of an anterior tooth with calcified canal which was untreatable with conventional root canal therapy and unable to track the position of the apex due to the absence of fistula.

• Design & Manufacturing
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• 제11권1호
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• pp.30-33
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• 2017

In this study, the mold technology for manufacturing of porous implant was investigated. Firstly, we considered the concept of insert molding technology with 3D printing of porous inert part. The part on implant was designed in the end region of the implant. And then main implant bodies were manufactured using conventional machining method. The other porous parts were designed and optimized with molding simulation. As the feature size of porous implant was so small that perfect feature of it using 3D printing technology could not be obtained. So, we proposed another scheme for manufacturing of the porous implant in the replace of the former approach. Polymer mold cores with 3D printing technology were considered. The effects of addictive manufacturing process parameters on the properties of mechanical and dimensional accuracy were investigated. Direct 3D printed polymer mold cores were designed and manufactured under the simulation of thermal and molding analysis. It was shown that 3D printed mold core with polymer could be adapted to the injection molding for porous implant.