• 한국기계가공학회지
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• 제21권5호
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• pp.1-8
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• 2022

Fused deposition modeling (FDM), based on stacking a continuous filament of polymer or composite materials, is well matured and is thus widely used in additive manufacturing technology. To advance FDM-based 3D printing technology, the mechanical properties of additively manufactured composite materials must be improved. In this study, we proposed a novel FDM 3D printing process using metal wire-polymer composites, enabling enhanced mechanical properties. In addition, we developed a new type FDM filament of copper wire wrapped in nylon material for stable 3D printing without thermal damage during the printing process. After FDM printing of the copper wire-nylon composite filament, we conducted a tensile test to investigate the mechanical behavior of the printed composite materials. The experimental results confirmed that the tensile strength of the 3D-printed metal wire-polymer composites was higher than that of the conventional single polymer material. Thus, we expect that the FDM printing process developed in this study may be promising for high-load-bearing applications.

• 한국기계가공학회지
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• 제21권2호
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• pp.137-143
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• 2022

Composite materials, being light-weight and of high mechanical strength, are increasingly used in various industries such as the aerospace, automobile, sporting-goods manufacturing, and ship-building industries. Recently, manufacturing of composite materials using 3D printers has increased. 3D-printed composite materials are made in free-form and adapted for end-use by adjusting the fiber content and orientation. However, research on the machining of 3D printed composite materials is limited. The aim of this study is to develop a machine learning method to select machining conditions for machining of 3D-printed composite materials. The composite material was composed of Onyx and carbon fibers and stacked sequentially. The experiments were performed using the following machining conditions: spindle speed, feed rate, depth of cut, and machining direction. Cutting forces of the different machining conditions were measured by milling the composite materials. PCA, a method of machine learning, was developed to select the machining conditions and will be used in subsequent experiments under various machining conditions.

• 한국공작기계학회논문집
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• 제17권2호
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• pp.77-82
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• 2008

Rubbing-roller is used for manufacturing liquid crystal display, and static displacement of the rubbing-roller becomes bigger as length of the rubbing roller made of aluminum is getting longer. Therefore, material of the rubbing-roller is changed from aluminum to CFRP(Carbon Fiber Reinforced plastic). Recently thermal spraying is applied to manufacturing process of long rubbing-roller. The thermal spraying has disadvantages such as increment of manufacturing time and fraction defective caused by density of stainless steel particle. In this study, fitting process by drawing was suggested and FEM analysis with Tsai-Wu failure theory and fitting experiments are carried out to find adequate shrink allowance. The suggested shrink allowance gives proper adhesive force, and CFRP failure is not occurred. Furthermore, the fitting process is applied to long rubbing-roller and availability of the fitting process is studied by measurement of roundness, straightness and shear strength.

• 한국기계가공학회지
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• 제18권4호
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• pp.41-47
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• 2019

The advent of highly integrated, high-power electronics requires low a coefficient of thermal expansion performance to prevent delamination between the heat dissipation material and substrate. This paper reports a preliminary study on the manufacturing technology of gas reaction control composite material, focusing on the prediction of the thermal expansion coefficients of Al-AlN composite materials. We obtained numerical equivalent property values by using finite element analysis and compared the values with theoretical formulas. Al-AlN should become the optimal composite material when the proportion of the reinforcing phase is approximately 0.45.

• 한국기계가공학회지
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• 제17권5호
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• pp.137-142
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• 2018

With the development of the electronic-materials industry, multi-functional metal-composite materials with high thermal conductivity and low thermal expansion must be developed for high reliability and high life expectancy. This paper is a preliminary study on the manufacturing technology of gas reaction control composite material, focusing on the prediction of the equivalent thermal properties of Al-AlN composite materials. Numerical equivalent property values are obtained by using finite element analysis and compared with theoretical formulas. Al-AlN composite materials should become the optimal composite material when the proportion of the reinforcing phase is less than 0.5.

• 항공우주시스템공학회지
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• 제17권2호
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• pp.71-77
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• 2023

액상성형공정(LCM, Liquid Composite Molding) 은 복합재료 오토클레이브(Autoclave) 성형공정의 단점을 극복할 수 있는 탈 오토클레이브(OoA, Out of Autoclave) 공정의 하나로 매우 복잡한 형상이나 대형 구조물을 일체형으로 만들 수 있어 항공산업에서 큰 경쟁력을 가진 공법으로 알려져 있다. 이러한 장점 때문에 액상성형공정을 적용한 항공 부품제작 수요가 늘고 있으며 FAA에서는 액상성형공정을 적용한 복합재료에 대한 인증(Qualification) 방법을 제시한 바 있다. 국내에서도 액상성형공정 적용 복합재료에 대한 부품제작 수요 및 재료인증 수요가 꾸준히 제기되고 있다. 따라서 본 연구에서는 기존에 구축된 프리프레그 복합재료 인증방안 이외에 LCM 공정을 적용한 복합재료에 대한 인증방안을 수립하기 위한 연구를 진행하였다.

• 한국재료학회지
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• 제29권1호
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• pp.23-29
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• 2019

Three-dimensional(3D) printing is a process for producing complex-shaped 3D objects by repeatedly stacking thin layers according to digital information designed in 3D structures. 3D printing can be classified based on the method and material of additive manufacturing process. Among the various 3D printing methods, digital light processing is an additive manufacturing technique which can fabricate complex 3D structures with high accuracy. Recently, there have been many efforts to use ceramic material for an additive manufacturing process. Generally, ceramic material shows low processability due to its high hardness and strength. The introduction of additive manufacturing techniques into the fabrication of ceramics will improve the low processability and enable the fabrication of complex shapes and parts. In this study, we synthesize silica composite material that can be applied to digital light processing. The rheological and photopolymeric properties of the synthesized silica composite are investigated in detail. 3D objects are also successfully produced using the silica composite and digital light processing.

• 한국기계가공학회지
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• 제18권12호
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• pp.28-37
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• 2019

Due to their flexible tailoring qualities, composites have become fascinating materials for structural engineers. While the research area of fiber-reinforced composite materials was previously limited to synthetic materials, natural fibers have recently become the primary research focus as the best alternative to artificial fibers. The natural fibers are eco-friendly and relatively cheaper than synthetic fibers. The main concern of current research into natural fiber-reinforced composites is the prediction and enhancement of the effective material properties. In the present work, finite element analysis is used with a numerical homogenization approach to determine the effective material properties of jute fiber-reinforced epoxy composites with various volume fractions of fiber. The finite element analysis results for the jute fiber-reinforced epoxy composite are then compared with several well-known analytical models.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.697-702
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• 2002

Composite material made of recycling paper and plastics was developed. The tension and bending testing result of developed composite material shows that the cellulose contained in paper contributes much to get high flexural rigidity. As an application example, the raised access floor for office automation purpose was developed by making use of developed composite material. Manufacturing process together with the extrusion die and the compression die for to manufacture the access floor have been developed.

• 한국기계가공학회지
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• 제18권1호
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• pp.65-71
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• 2019

The development of adsorbed natural gas (ANG) has emerged as one of potential solutions. It is desirable to reduce the weight of vessel by applying light-weighed a composite carbon fiber in order to response to a egulation of $CO_2$ emission. Through understanding of a composite carbon fiber, and material characteristic of a composite carbon fiber is required in order for better application of a reduction of weight and an analysis of material characteristic. Herein, this study suggest the composite carbon fiber vessel applied to the characteristic of carbon fiber, and it decides the preliminary shape based on the test of material characteristic for ANG vessel applied to a composite carbon fiber, and its basic shape calculate through on the netting theory. Moreover, the detail shape design is analyzed by a finite element analysis, and in the stage of detail sahp design and analysis of stress was performed on the typical shape using a finite element analysis, and the result of preliminary design was verified.