• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.7
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• pp.34-42
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• 2022

Minimizing the backlash of gears and reducers is important for their proper and precise functioning. In this study, an automatic backlash measuring system was developed for the mass production and quality control of a military-grade reducer. The developed automatic backlash measurement system eliminates human error during the backlash measurement process. It also reduces the manufacturing time and digitizes the backlash number. The system was tested for an aircraft machine gun control reducer that required low-torque and high-precision conditions. The test results show that the torque range was 0.820-4.788 Nm. The maximum torque error is less than 0.231 N·m at 2.943 N·m, and 1.2 arcmin of the maximum backlash error with ± 0.3 arcmin of repeatability. The developed system satisfies all required conditions: torque of 1-3 Nm, torque accuracy within ± 0.5 N·m, and backlash accuracy of ± 3 arcmin.

• Proceedings of the Korea Technology Innovation Society Conference
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• 2000.11a
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• pp.227-245
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• 2000

Korean firms have attempted to catch up in the aircraft industry during last quarter century. Korean firms have built up their capabilities by moving from parts manufacturing through subassembly to system integration. The number of projects carried out and the intensity of technological effort undertaken by firms strongly influences market position and firm performance. However, successful catching up is not simply dependent on capability building within the firm. The national environment (Porter, 1990) in which firms are located plays a pivotal role. The Korean government has been effective in creating a favorable environ-ment in many areas, but has not been able to replicate this success in the aircraft industry. Opportunities for learning in the aircraft industry have been hampered by the small size of the Korean civilian aircraft market and the sophisticated requirements of military systems. A policy of domestic rivalry in airframe manufacture has created too many firms for such a small market. The ability of Korean firms to catch up in the aircraft industry depends on both the internal capabilities of firms as well as appropriate government policies and the involve- ment of government research institutions and universities over an extended period of time. There have been many studies about the catching up of developing countries in mass production (such as automobile, consumer electronics, and recently DRAM), but few in complex systems, such as aircraft.

• Aerospace Engineering and Technology
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• v.4 no.2
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• pp.236-243
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• 2005

Civil aircraft tires require a certification according to the Technical Standard Order Authorization(TSOA) procedure. TSO-C62d contains minimum performance standards for aircraft tires. The TSOA covers design and manufacturing of the tire only. To install a TSO article on aircraft requires an installation approval. In this paper, TSOA procedure and the certification requirements for aircraft tires will be presented.

• Composites Research
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• v.35 no.2
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• pp.106-114
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• 2022

Carbon fiber-reinforced plastic, well known high specific strength and high specific stiffness, have been widely used in the aircraft industry. Mostly the CFRP structure is fabricated by lamination of carbon fiber or carbon prepreg, which has major disadvantage called delamination. Delamination is usually produced due to absence of the through-thickness direction fiber. In this study, three-dimensional carbon preform woven in three directions is used for fabrication of aircraft wing unit structure, a part of repeated structure in aircraft wing. The unit structure include skin, stringer and rib were prepared by resin transfer molding method. After, the 3D structure was compared with laminate structure through compression test. The results show that 3D structure is not only effective to prevent delamination but improved the mechanical strength. Therefore, the 3d preform structure is expected to be used in various fields requiring delamination prevention, especially in the aircraft industry.

• Journal of Aerospace System Engineering
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• v.11 no.1
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• pp.35-40
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• 2017

Aircraft diagnostic systems identify system failures and nip aircraft accidents in the bud by removing hazards that hinder Safety Of Flight (SOF). The necessity for diagnostic systems is increasing as aircraft manufacturing technology is modernized. Many countries have conducted studies and developed diagnostic systems. However, studies about diagnostic systems are very few in Korea. This study defines the scope of aircraft diagnostics systems and closely considers methods to ensure the Safety Of Flight (SOF) for military aircraft.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.4
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• pp.1-8
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• 2020

Mechanical components that support structures in aerospace and power generation industries require high-strength materials. Particularly, in the aerospace industry, aluminum alloys, titanium alloys, and composite materials are increasingly used due to their high maneuverability and durability to withstand low temperature extreme environments; however, ultra-high-strength steel is still used in key components under heavy loads such as landing gears. In this paper, the fault cause analysis and troubleshooting of aircraft parts made of ultra-high-strength steel (300M) broken during normal operation are described. To identify the cause of the defect, a temporary inspection of the same aircraft was performed, and material testing, non-destructive inspection, microstructure examination, and fracture area inspection of the damaged parts were performed. Fracture analysis results showed that a crack in the shape of a branch developed from the tool mark in the direction of the intergranular strain. Based on the results, the cause of fracture was confirmed to be stress corrosion.

• Journal of Power System Engineering
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• v.18 no.1
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• pp.84-90
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• 2014

The high pressure hoses are widely used for the vehicles, aircraft, and overall industries. The hose assembly is generally composed of a nipple, a socket and a hose with reinforcement layers to increase the tensile strength. To produce the hose assembly, crimping or swaging process is usually used to clamp its components to ensure the prevention of fluid leakage. Crimping is a cold-working technique to form a strong bond between the workpiece and a non-metallic component. The crimping stroke is a primary parameter to be determined in the metalworking process, and it plays an important role in hose performance. This study aims at investigating the optimal crimping stroke according to the size of aircraft high pressure hose by using MSC/MARC. It is supposed that the results can be useful to get the information about the crimping stroke in manufacturing process, even with the different size of a hose.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.3
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• pp.87-93
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• 2011

CNC lathe machining has been widely used for parts machining of vehicles, aircraft, ships, electronics, etc. because cost savings for shortening processing time and increasing productivity are great. In this study, the purpose is to investigate the effect of cooling methods such as oil mist, water-soluble cutting oils on the workpiece surface roughness with the cutting speed, cutting depth, tool nose radius and feed rate of CNC lathe machine as a parameter in the cutting process of the aluminum alloy 2024 which is used a lot recently on aircraft parts. It is found that oil mist is coolant and water-soluble cooled by cutting the experimental conditions, cutting speed and cutting depth without effecting the surface roughness value was constant.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.29-35
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• 2010

Recently the industry high-speed machining has been applied to the automotive, aircraft, electronics parts machining because the effect of cost savings, machining time reduction and productivity improvement. In this study recently the aircraft structural aluminum alloy 7075 used in cutting the ball end-mill on the surface roughness terms most affect the parameters of the spindle speed and feed rate on the surface roughness of the work-piece according to the cutting depth is to investigate. Cutting depth at 0.3 mm has the lowest surface roughness.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.49-55
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• 2020

Studies on the optimizations of machining processes use two different methods. The first is feed control in real-time by spindle load in a machine tool. The second is feed scheduling in NC code control by material removal rate using a CAD/CAM system. Each approach possesses its respective merits and issues compared to the other. That is, each method can be complementary to the other. The purpose of the study is to improve the productivity of the bulkhead, an aircraft Duralumin structure. In this paper, acceleration or deceleration of cutting tool by spindle load data is achieved using adaptive feed control macro programming in a machine tool.