• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.885-894
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• 2023

Setting RAM target value for a defense system plays a crucial role in the development and design phases and the production phase as well. It is apparent that the achieved RAM target value can help maximizing the combat capability of a defense system and improving its performance throughout the system's life cycle from acquisition phase to disposal. Usually a defense system operates according to its OMS/MP (Operational Mode Summary / Mission Profile) and it consists of several subsystems which are supposed to be operated at each utilization rate under its operating conditions and the mission profiles assigned. In this study, a method of setting RAM target value is proposed for a defense system that are composed of several independent subsystems considering their utilization rates and the mission profiles assigned. And the case study of applying the proposed method of setting RAM target value to system A is dealt with.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.36 no.4
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• pp.100-108
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• 2013

In aerospace industry, MTBF (Mean Time Between Failure) and MFTBF (Mean Flight Time Between Failure) are generally used for reliability analysis. So far, especially to Korean military aircraft, MFTBF of avionic equipments is predicted by MIL-HDBK-217 and MIL-HDBK-338, however, the predicted MFTBF by military standard has a wide discrepancy to that of real-world operation, which leads to overstock and increase operation cost. This study analyzes operational data of avionic equipments. Operational MFTBF, which is calculated from operational data, is compared with predicted MFTBF calculated conventionally by military standard. In addition, failure rate trend is investigated to verify reliability growth in operational data, the investigation shows that failure rate curve from operational data has somewhat pattern with decreased failure rate and constant failure rate.

• Carbon letters
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• v.10 no.1
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• pp.43-51
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• 2009

Carbon fibers are a new breed of high-strength materials. The existence of carbon fiber came into being in 1879 when Edison took out a patent for the manufacture of carbon filaments suitable for use in electric lamps. However, it was in the early 1960s when successful commercial production was started, as the requirements of the aerospace industry for better and lightweight materials became of paramount importance. In recent decades, carbon fibers have found wide applications in commercial and civilian aircraft, along with recreational, industrial, and transportation markets as the price of carbon fiber has come down and technologies have matured. The market for carbon fiber has experienced a good growth in recent years. The growth rate for the last 23years was about 12%. The article reviewed 9,641 Korea, U.S., Japan, Europe patents issued in the carbon fibers in order to offer additional insight for researchers and companies seeking to navigate carbon fiber patent landscape. This article will provide you with all the valuable information and tools you will need to investigate your study successfully within the carbon fiber field. This article also will save you hundreds of hours of your own personal research time and will significantly benefit you in expanding your business in the carbon fiber market.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.1 no.1
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• pp.79-88
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• 2002

High speed machining system have been used in industrial because it is effective to a material manufacturing with various shape. Recently the end-milling processing is needed the high-precise technique with good surface roughness and rapid time in aircraft, automobile part and molding industry. Therefore this study proposed to decide best manufacturing cutting condition for surface roughness and rapid manufacturing tune by using computer Image processing system and 3D modelling. Until the 16,000 rpm, the surface roughness is decreased rapidly, but it is not over that. The 22,000 rpm is the spindle speed with the optimum surface in the high speed end-milling. In the case of the feed rate with 2,000 mm/mm and 8,000 mm/mm, the surface roughness is better than 4,000 mm/min and 6,000 mm/min. By using the 3D modelling, it is effectively represented shape characteristics of working surface m high speed end-milling.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.15 no.4
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• pp.53-63
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• 2007

This paper examines the safety perception of passengers on low cost carriers which has made several accidents and incidents at the early stage of their business. The concept of low cost carrier is becoming more important to airline industry in Korea. This study achieves the first selecting attribute among airline service factors on domestic flights and try to indicate that how much the passengers trust in the safety of low cost carriers. It is also sets the comparative safety awareness between low cost carriers and two full service national carriers in domestic market. The safety perception of aircraft type can be a major factor for LCC choice in Korea due to frequent accidents and incidents for last two years. More than 60% of LCC passengers have increasingly considered the safety after recent accidents. The low cost airlines' images of the passengers showed that the first image of the LCC was the fare and the second image was safety. This study indicates that most of the LCC travelers will use the international low cost airlines when LCC extend their destination to adjacent countries. For the accomplishment of the low cost carriers' competitiveness in domestic market, they have to try to get rid of bad image for safety and pay extra attention to find out better services other than the safety and develop other strategies to compete against existing full service carriers.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.3
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• pp.1-8
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• 2018

Aviation industry is growing rapidly, and this growth is expected to continue. However, aircraft accident rate is still high, and 65 percent of accidents occur during landing phase due to unstable approach. Therefore, this research analyzed causes and countermeasures of unstable approach. In order to derive countermeasures, this study selected P International Airport as an example case. In addition, this research analyzed A airline's FOQA data, regional Standard Operating Procedures, and 5 years of environmental factors to identified correlation of those contributing factors. In conclusion, his research concluded following results. First of all, because of P International Airport's geological features, pilots are required to conduct Circling Approach, and this advanced maneuver increases workload at the final stage of flight. Secondarily, meteorological factors such as crosswind, seasonal rain front, local visibility contributes unstable approach. Lastly, these geological and meteorological factors are interrelated, and this uncommon environment can decrease circumstantial judgement ability of pilots and jeopardize aviation safety. As a consequence, it is recommended to reinforce the Crew Resource Management and Threat & Error Management systems so that pilots can perceive identical safety target.

• Journal of the Korean Society of Systems Engineering
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• v.13 no.1
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• pp.57-65
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• 2017

Recently, the ratio of electrical part and embedded software has grown in automotive industry. ISO 26262, 'Road Vehicles - Functional Safety', was published to guide development of automotive electrical and electronic part in 2011. This paper describes definition of functional safety and analyzes ISO 26262. The comparison of ISO 26262 and DO-178C is made, then difference between them is identified. DO-178C provides guidance for the production of software for airborne system and equipment. The core of DO-178C is a relatively minor update to the previous DO-178B, however, the big changes are captured in the supplemented documents such as DO-331, 'Model-Based Development and Verification Supplement to DO-178C and DO-278A'. Model-based design is important to develop automotive and aircraft meeting the guidelines of ISO 26262 and DO-178C. In this paper, the sample case of applying MBSE(Model-Based Systems Engineering) to AVCS(Active Vibration Control System) software development is discussed.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.18 no.4
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• pp.44-50
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• 2010

Structural vibration is a significant problem in many multi-part or multi-component assemblies. In aircraft industry, structures are composed of various fasteners, such as bolts, snap, hinge, weld or other fastener or connector (collectively "fasteners"). Due to these, prediction and design involving dynamic characteristics is quite complicated. However, the current state of the art does not provide an analytical tool to effectively predict structure's dynamic characteristics, because consideration of structural uncertainties (i.e. material properties, geometric tolerance, dimensional tolerance, environment and so on) is difficult and very small fasteners in the structure cause a huge amount of analysis time to predict dynamic characteristics using the FEM (finite element method). In this study, to resolve the current state of the art, a new approach is proposed using the FEM and probabilistic analysis. Firstly, equivalent elements are developed using simple element (e.g. bar, beam, mass) to replace fasteners' finite element model. Developed equivalent elements enable to explain static behavior and dynamic behavior of the structure. Secondly, probabilistic analysis is applied to evaluate the PDF (probability density function) of dynamic characteristics due to tolerance, material properties and so on. MCS (Monte-Carlo simulation) is employed for this. Proposed methodology offers efficiency of dynamic analysis and reality of the field as well. Simple plates joined by fasteners are taken as an example to illustrate the proposed method.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.11a
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• pp.888-891
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• 2000

Drilling is one of the most important operations in machining industry and usually the most efficient and economical method of cutting a hole in metal. From automobile parts to aircraft components, almost every manufactured product requires that holes are to be drilled for the purpose of assembly, creation of fluid passages, and so on. It is therefore desirable to monitor drill wear and hole quality changes during the hole drilling process. One important aspect in controlling the drilling process is drill wear status monitoring. With the monitoring, we may decide on optimal timing for tool change. The necessity of the detection of tool wear, fracture and the abnormal tool state has been emphasized in the machining process. Accordingly, this paper deals with the cutting characteristics of the hot-rolled high strength steels using common HSS drill. The performance variables include drill wear data obtained from drilling experiments conducted on the workpiece. The results are obtained from monitoring of the cutting force and Acoustic Emission (AE) signals, and from the detection of the abnormal tool state with the computer vision system.

• 한국항공우주법학회:학술대회논문집
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• 2008.05a
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• pp.121-140
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• 2008

Most compensation issues are regulated under domestic law where third parties are suffered damage from crushes of aircrafts or their falling objects. This issue was internationally recognized. A Convention to unify the rules of the law concerning damage caused by aircraft to the third parties on the surface was signed in May,1933( the 1933 Rome Convention) and it became effective in 1942. Later, modernization was carried out through the 1952 Rome Convention and the 1978 Montreal Protocol amending the 1933 Rome Convention. Ratifying States either to the Convention or to the Protocol is not as many as those States to the Warsaw Convention concerning air transport. In 1999, which was a turning point of changes of centuries from the twentieth century to the twenty first century, the Montreal Convention was passed to modernize the Warsaw Convention, and was quickly widespread. On September 11 2001, the coordinated simultaneous terror attacks occurred. In the circumstances, the issue modernizing the Rome Convention came up. Thus, workout under the initiatives of the Legal Committee of the ICAO is under operation to adopt new Rome Convention. In Japan, a study on the draft of the treaty was operated by which a working study group composed of experts from academy, industry and government was set up. This article, being based on that study, clarifies issues and gives future perspectives. This article presents author's individual views.