• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.6
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• pp.41-46
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• 2017

Productivity improvement and cost reduction in the aircraft industry have become major industrial objectives, and improving productivity by reducing machining time has become a key focus. When numerical cutting code is created by CAM software, such as CATIA or UG-NX, it is impossible to control machining feed speed using cutting force changes depending on the machining tool path. However, machining an aircraft engine part from difficult material, such as Inconel 718, takes a long time, and tool chipping or breakage often occurs from forcing the machining path too quickly. This study investigated and verified the reliability of the AdvantEdge production module (PM)using cutting power tests. In particular, diffuser and diffuser case parts were considered, comparing cutting power and machining time using AdvantEdge PM and CATIA.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.103-110
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• 2018

The modern aircraft consists of tens/hundreds of thousands of components. A large proportion of these components are manufactured using a machining process. A deburring process must be performed after to machining. This study investigates the effect of changes in the deburring wheel rpm on the deburring force and radius. The deburring wheel is used to trim sharp edges off machined parts of the aircraft. The deburring wheel used consists of a core and a nylon hair(this new concept is protected under patent). We find that higher deburring wheel rpm results in increased deburring force and radius. For deburring wheel rotation rates of 500~750rpm, deburring force of 3.4~6.5kgf and deburring radius of 0.4~0.5mm were observed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.2
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• pp.45-50
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• 2021

In the recent fourth industrial revolution, the demand for additive processes has emerged rapidly in many mechanical industries, including the aircraft and automobile industries. Additive processes, in contrast to subtractive processes, can be used to produce complex-shaped products, such as three-dimensional cooling systems and aircraft parts that are difficult to produce using conventional production technologies. However, the limitations of additive processes include nonuniform surface quality, which necessitates the use of post-processing techniques such as subtractive methods and grinding. This has led to the need for hybrid machines that combine additive and subtractive processes. A hybrid machine uses additional additive and subtractive modules, so product deformation, for instance, deflection, is likely to occur. Therefore, structural analysis and design optimization of hybrid machines are essential because these defects cause multiple problems, such as reduced workpiece precision during processing. In this study, structural analysis was conducted before the development of an additive/subtractive hybrid processing machine. In addition, structural optimization was performed to improve the stability of the hybrid machine.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.11
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• pp.52-59
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• 2021

Titanium alloy (Ti-alloy) is widely used as a material for core parts of aircraft structures and engines that require both lightweight and heat-resistant properties owing to their high specific stiffness. Most parts used in aircraft have I-, L-, and H-shaped thin-walled structures for weight reduction. It is difficult to machine thin-walled structures owing to vibrations and deformations during machining. In particular, cutting tool damage occurs in the corners of thin-walled structures owing to the rapid increase in cutting force and vibration, and machining quality deteriorates because of deep tool marks on machined surfaces. In this study, milling experiments were performed to derive an effective method for machining a L-shaped thin-walled structure with Ti-alloy (Ti-6Al-4V). Three types of machining experiment were performed. The surface quality, tool wear, cutting force, and vibration were analyzed comprehensively, and an effective machining method in terms of tool life and machining quality was derived.

• Journal of the Ergonomics Society of Korea
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• v.29 no.5
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• pp.751-762
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• 2010

The purpose of this study was to investigate the job stress factors of aircraft composite material part manufacturing workers using survey based on 'Job stress factors evaluation tool for Koreans' that was developed by KOSHA in 2003. Two hundred and fifty workers participated in this study, and among them 204 responses were analyzed for this study due to the unreliability and insincerity of responses. The eight job stress factors which are physical environment, job autonomy, job insecurity, organizational system, workplace culture, unfair compensation, relationship conflict, and job requirement were analyzed. The results showed that the stress level of the six job stress factors which are physical environment, job autonomy, job insecurity, organizational system, workplace culture, unfair compensation was relatively higher than that of other industry workers. Generally, all eight job stress factors showed higher stress with temporary workers than with permanent workers, and especially job autonomy, job insecurity, organizational system, and unfair compensation factors showed statistically significant differences (p<0.05). Since the temporary workers are insecure with their job, weak position in organization, having little self-control for the job and lower pay level than that of permanent workers though the job is as same as permanent workers', the stress level of above job stress factors would be much higher than that of the other factors. The group of unsatisfactory with workplace showed higher job stress than group of satisfactory with workplace in all job stress factors, as expected, at the statistically significance level (p<0.05). From the results of this study, the work loss due to the job stress could be prevented, and accurate stress factors could be removed at the workplace. Also the job stress management program can be implemented to improve the work efficiency and the workers' quality of life.

• Journal of Aerospace System Engineering
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• v.10 no.1
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• pp.43-50
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• 2016

In order to suggest the optimal manufacturing technology of composite wings of solar-powered unmanned aerial vehicles, this study compared forming technologies to reduce wing weight for long-endurance flight and to improve the manufacturing process for cost-saving and mass production. It compared the manufacturing time and weight of various composite wing molding technologies, including cocuring, secondary bonding, and manufacturing by balsa. As a result, wing weight was reduced through cocuring methods such as band type composite fiber/tape lamination technology, which enabled prolonged flight duration. In addition, the reduced manufacturing time led to a lower cost, which is a good example of weight lightening for not only small solar-powered UAVs, but also composite aircraft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.12
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• pp.969-976
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• 2020

Urban Air Mobility is attracting attention as a future innovation industry around the world, and leading industries are considering the application of composite materials for structural robustness and lightening in the designing and manufacturing new concept eVTOL aircraft. To apply composite materials to the new concept of eVTO aircraft, this paper was analyzed about composite material qualification system of FAA & EASA and institutionalized by Korea Government, including the procedures and methods, the organization to carry out the material verification for domestic conditions. The domestic composite material qualification system will not only make it easier for manufacturers of eVTOL aircraft with a new concept to apply composite materials to domestic aircraft through pre-material qualification, but also reduce the burden of material qualification within the period of type certification. In addition, domestic manufacturers of composite materials with qualified material quality and performance will be easy to enter for domestic aircraft applications and composite material manufacturers with experience in applying to aircraft will have a positive impact on overseas exports. This system will be able to promote the development eVTOL aircraft industry of a new concept and enhance international credibility of made aircraft in Korea.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.4
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• pp.117-122
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• 1998

Glass fiber epoxy composite material is widely used in the structures of aircrafts, robots and other machines because of their high specific strength, high specific stiffness and high damping. In order for the composite materials to be used in the aircraft structures or machine elements, accurate surfaces for bearing mounting or joint must be provided, which require precise machining. In this paper, the machinability of the glass fiber epoxy composite material was experimentally investigated. The results can be summarized as follows : 1. The entrance of hole is very good manufacturing existing, but exit come to occur sever surface exfoliation. 2. The cutting force in drilling of the glass fiber epoxy composite material is decreased as the drilling speed increased. 3. If the glass fiber epoxy composite material is drilling by the standard twist drill, then the hole recommand cutting condition is spindle speed 400∼600rpm, feed 40∼50mm/min.

• Advances in aircraft and spacecraft science
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• v.2 no.2
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• pp.183-198
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• 2015

Scramjets are a class of hypersonic airbreathing engine that are associated with realizing the technology required for economical, reliable access-to-space and high-speed atmospheric transport. After-burning augments the thrust produced by the scramjet nozzle and creates a more robust nozzle design. This paper presents a numerical study of three parameters and the effect that they have on thrust augmentation. These parameters include the injection pressure, injection angle and streamwise injection position. It is shown that significant levels of thrust augmentation are produced based upon contributions from increased pressure, mass flow and energy in the nozzle. Further understanding of the phenomenon by which thrust augmentation is being produced is provided in the form of a force contribution breakdown, analysis of the nozzle flowfields and finally the analysis of the surface pressure and shear stress distributions acting upon the nozzle wall.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.67-72
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• 2019

In manufacturing sites that process and produce parts in large quantities for the automotive and electronics industries, users require the reducing of costs and shortened delivery times. To meet these demands, an increase in the number of processes and an decrease in assembly times need to be addressed. Gantry loaders currently on the market in Korea are mostly used for processing lightweight and simple shapes and are not suitable for conveying and processing complex shapes such as automobile engines and aircraft parts. This makes it difficult to mount the material in place. This study aims to smoothen the transportation of complex shapes through the development of jigs and various approaches in the installation of the feed shaft by researching the gantry loader system for transporting multiple materials with complex shapes.