• 한국초전도ㆍ저온공학회논문지
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• 제24권1호
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• pp.8-12
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• 2022

Recently, research on applying composite materials to various industrial fields is being actively conducted. In particular, composite materials fabricated by Fused Deposition Modeling 3D printers have more advantages than existing materials as they have fewer restrictions on manufacturing shape, reduce the time required, weight. With these advantages, it is possible to consider utilizing composite materials in cryogenic environments such as the application of liquid oxygen and liquid hydrogen, which are mainly used in an aerospace and mobility. However, FDM composite materials are not verified in cryogenic environments less than 150K. This study evaluates the characteristics of composite materials such as tensile strength and strain using a UTM (Universal Testing Machine). The specimen is immersed in liquid nitrogen (77 K) to cool down during the test. The specimen is fabricated using 3D print, and can be manufactured by stacking reinforced fibers such as carbon fiber, fiber glass, and aramid fiber (Kevlar) with base material (Onyx). For the experimental method and specimen shape, international standards ASTM D638 and ASTM D3039 for tensile testing of composite materials were referenced.

• Composites Research
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• 제15권6호
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• pp.38-43
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• 2002

쾌속조형(Rapid Prototyping)기술은 다양한 형태치 재료를 사용하여 초기모형을 제작할 수 있다. Stratasys사의 FDM은 플라스틱 재료로 조형물을 제작하는 대표적인 쾌속조형공정이다. 또한 FDM으로 제작된 부품들은 하중을 받는 구조용 재료로도 사용된다. FDM은 약 300$\mu$m 두께의 가는 필라멘트의 형태의 일정한 방향으로 재료를 적층하므로, FDM으로 제작된 부품들은 이방성 재료의 성질을 나타낸다. 본 연구에서는 FDM 부품의 인장강도를 예측하기 위한 해석방법을 제시하고자 한다. 복합재를 위한 Classical Lamination Theory를 사용하여 컴퓨터 코드를 작성하였다. FDM 제품의 파괴를 예측하기 위하여 계산펀드에 Tsai-Wu failure criterion 이론을 도입하였다. 해석방법에 의해 예상되는 인장강도와 실제 실험으로 얼은 수치를 비교하였다. 예상치가 측정치에 근사한 값을 보이므로 본 계산식의 타당성이 입증되었다. 덧붙여서 FDM의 강도계산과 설계규칙이 웹기반의 제안서비스(FDMAS)에서 제공된다.

• 컴퓨터교육학회논문지
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• 제19권4호
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• pp.45-58
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• 2016

이 논문은 2년의 수학-정보 통합 영재교육 과정을 마치고 사사과정에 진입한 중학생들이 IT 융합 팀 프로젝트를 수행한 사례를 분석하고 형성평가의 관점에서 사사과정 프로그램을 보완할 요인을 도출하였다. 담당 교수는 학생들이 중학생 3학년의 수준과 사사 과정의 특징을 감안하여 로봇키트와 미디어를 융합한 상호작용적 IT 융합 프로젝트를 자기주도적으로 해 나갈 수 있도록 안내해 주었다. 2015년 2월부터 12월까지 진행된 사사과정 기간 동안 팀 프로젝트 수행 과정에 관한 문서와 보고서를 비롯하여 사진 및 동영상 자료, 작업 결과물, 학생들과의 면담 자료를 수집하여 분석하였다. 참여 학생들의 컴퓨팅 실력과 IT 융합 프로젝트에 대한 흥미가 제각기 달랐음에도 팀별 프로젝트 수행은 아이디어 탐색과 설계에 해당되는 초기 단계보다 그 이후의 구현 단계에서 적극적이고 안정된 패턴을 보여주었다. 또한 학생들의 산출물을 연구와 교육(R&E)의 9단계 모델에 따라 형성평가한 결과 작품 완성도에서 상중하에 따른 개인별 차이를 보여주었다. 끝으로 이 사례는 향후에 질적으로 보완해야 할 방향 및 사사교육에 대한 시사점을 제시하였다.

• 대한기계학회논문집A
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• 제41권7호
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• pp.607-612
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• 2017

최근 다양한 분야에 적용되고 있는 적층 가공 기술(AM)은 복잡한 형상 제조 및 재료 비용 절감으로 인해 혁신적인 제품 생산 방법으로 각광을 받고 있다. 그 중에서도 압출적층조형(Fused Deposition Modeling, FDM) 공정을 통한 친환경 부품 제조는 의료 분야산업에서 많은 주목을 받고 있다. 따라서, 본 논문에서는 친환경 생분해성 재료인 Poly Lactic Acid(PLA)를 사용한 FDM 공정 실험을 수행하고 제작된 적층 시편에 대한 인장 시험을 적용하여 주요 FDM 공정 변수인 적층 두께, 적층 방향, 적층 충진량이 인장 시편의 기계적 성질에 미치는 영향을 정량적 및 정성적으로 분석하고 이를 극대화하는 각 공정 변수의 최적값을 도출하였다.

• 대한치과기공학회지
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• 제35권2호
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• pp.113-120
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• 2013

Purpose: This study was to observe surface property and bonding strength according to composition of Ni-Cr alloy for porcelain fused to metal crown. The two kinds of Ni-Cr alloy with different composition ratio of parent metal were observed general properties and chemical properties of each alloy surface and measured the shear bonding strength between ceramic and each alloys. The aim of study was to suggest the material for design of parent metal's composition ratio to development of alloy for porcelain fused to metal crown. Methods: The two kinds of alloy as test specimen was Ni(71wt.%)-Cr(12wt.%) and Ni(63wt.%)-Cr(23wt.%) alloy. The oxide on surface was observed by SEM and EDX. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element O within $Ni_{71}Cr_{12}$ alloy measured 12.74wt.%, but $Ni_{63}Cr_{23}$ alloy was measured 15.91wt.%. And the maximum shear bonding strength was measured 106.14MPa between $Ni_{71}Cr_{12}$ alloy and vintage halo (VV group). Conclusion: The surface property and oxide characteristic of $Ni_{71}Cr_{12}$ alloy was similar to $Ni_{63}Cr_{23}$ alloy. And VV group has the strongest shear bonding strength.

• 대한치과기공학회지
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• 제35권4호
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• pp.359-364
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• 2013

Purpose: This study was to observe characteristic of metal oxidation and bonding strength according to composition of Ni-Cr alloy for porcelain fused to metal crown. The three kinds of Ni-Cr alloy with different composition ratio of parent metal were observed general properties and chemical properties of each alloy surface and measured the shear bonding strength between ceramic and each alloys. The aim of study was to suggest the material for design of parent metal's composition ratio to development of alloy for porcelain fused to metal crown. Methods: The three kinds of alloy as test specimen was Ni(59wt%)-Cr(24wt%), Ni(67wt.%)-Cr(16wt.%) alloy and Ni(71wt%)-Cr(12wt%)alloy. The oxide on surface was observed by EDX. And the shear test was performed by MTS. Results: The surface property and oxide characteristic analysis of oxide layer, weight percentage of Element O within $Ni_{59}Cr_{24}$ alloy measured 23.03wt%, $Ni_{67}Cr_{16}$ alloy measured 21.13wt% and $Ni_{71}Cr_{12}$ alloy was measured 48.55wt%. And the maximum shear bonding strength was measured 58.02Mpa between $Ni_{59}Cr_{24}$ alloy and vintage halo(H2 group). Conclusion: The surface property and oxide characteristic three kind of Ni-Cr alloy was similar. and shear bonding strength showed the highest bonding strength in H2 specimens.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2005년도 추계학술발표대회 논문집
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• pp.205-206
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• 2005

The plan for Shinseon Seolleongtang Restaurant in Kimpo has as its goal to create an environment strongly fused with the design of the modern city and the spirit of food culture craftsmanship, and it proceeded as follows. In order to carry out the goal of the plan, the direction of the design concept was set to be a harmonious blending of Ecology and Minimal. Also, for detailed plan direction, in the Minimal domain, conciseness, cleanliness, and high quality were established as the ultimate goals in order to create a spacious food and drink area in today's complicated and energy-draining society, and in the Ecology domain, ancient hieroglyphs representing the forms of natural objects were used that prayed for years of plentiful harvest and blessing, and colorfully expressed the events of the populace.

• 한국의상디자인학회지
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• 제6권2호
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• pp.103-109
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• 2004

This study attempted to investigate the plasticity of Korean paper expressed in contemporary fashion after general inquiry into Korean paper and examine the aesthetic beauty of fashion design using Korean paper. It used the literature review and empirical data analysis together. Korea-paper fashion design, the object of actual investigation, was for Korean-paper fashion from the 1990s to the present. As a result of analysis, the following findings were obtained: First, the natural, warm and soft texture seen as pureness in Korean paper enables us to elicit naturalness from liberalness. In addition, Korean paper not only has the tough characteristic of its material but also has the natural characteristic of abandoning its original nature and complying and adhering to its a given nature. Korean-paper fashion design, using this natural beauty and frank nature, bears the pure image of excluding decoration. Second, the overlapping of the surface on the surface expressed in Korean-paper fashion design forms one space with the sense of depth because of its transparency and expresses temporality through repetition. And the work of folding it with other materials and pasting them up with together demonstrates the effect of reflection because its original transparency. This effect is the specificity created in the collage technique using Korean paper and is the advantage of coming to obtain a wider freedom of expression. Korean-paper fashion design expresses transparency using this repetition and overlapping, Third, Korean paper has the simple rather than luxurious aspect. Owing to this nature, fashion design looks as if there were the greed inherent behind the work made from Korean paper though the complex technique applied to it. And it expresses the restraint of Korean paper using its original white color, the exclusion of decoration and simple design. Fourth, Korean paper is more likely to be changed by the outside influence because of formation. It has its peculiar aesthetic value and original artistry to an extent that it is regarded as one artistic work. The quality and texture of Korean paper diversely vary according to the artist's working process. Like this, Korean paper is easily fused into some object without exclusivity though it may be added to it. Korean-paper fashion design has the beauty of creation that is to create a new world because Korean paper is fused into another material due to its soft nature.

• 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.

• 한국기계가공학회지
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• 제17권3호
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• pp.93-101
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• 2018

FDM is one of the popular 3D printing technologies because of an inexpensive extrusion machine and multi-material printing. FDM can use thermoplastics such as ABS and PLA. The 3D-printed ABS parts fabricated by FDM are attractive in the automotive industry because of their weight. A 10% reduction in weight can increase the fuel economy by approximately 7%. To use 3D-printed ABS parts as automotive parts, we should evaluate the 3D-printed parts in terms of automotive reliability. In this study, 3D-printed ABS samples were evaluated using Ono's rotary bending fatigue test. We obtained an S-N curve for the 3D-printed ABS specimen from the finite-element analysis. The S-N curve can be useful in early-stage design decisions for 3D-printed ABS parts.