• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.25 no.2
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• pp.108-115
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• 2015

Electro-mechanical actuator installed on aircraft consists of a decelerator which magnifies the torque in order to rotate an axis connected with aircraft control surface, a control section which controls the motor assembly through receiving orders from cockpit and a motor assembly which rotates the decelerator. Electro-mechanical actuator controls aircraft altitude, position, landing, takeoff, etc. It is an important part of a aircraft. Aircraft maneuvering causes vibrations to electro-mechanical actuator. Vibrations may result in structural fatigue. For that reason, it is necessary to analyze the system structural safety. In order to analyze the system structural safety. It is needed reasonable finite element model and structural response stress closed to real value. In this paper, analytic model is derived by using the simplified finite element model, and damping ratio which is closely related to response stress is derived by using modal test. So, we developed analytic model in less than 10 % error rate, compared with modal test. Vibration response stress close to real value was estimated from analytic model modified with modal experimental damping ratio. Estimation method for damping ratio with empirical formula was suggested partly. Finally, It was proved that electro-mechanical actuator had reasonable structure margin of safety at environmental random $3{\sigma}$ stress during life cycle.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.1
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• pp.31-63
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• 2011

Since Korea has invested only on developing an aircraft, it is true that Korea has neglected detailed standards and procedures about certification activities including essential safety procedures. Most developed countries have implemented mandatory airworthiness system by legislating it for operational safety of aircraft based on ICAO Annex 8, and the U.S. Department of Defense and the FAA's Airworthiness system have been adapted it to the realities of their circumstance. Therefore, Airworthiness system that can guarantee the safety of the aircraft at international level is necessary to enhance flight safety and to create export opportunities of an aircraft as a country which can develop an aircraft by itself To achieve this, a study on the improvement of aircraft airworthiness was carried out by analyzing the problem of domestic airworthiness system and by reflecting international best practices on the establishment of a system for improved Airworthiness.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.42-51
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• 2022

An eVTOL aircraft, which is required to operate with low pollution/low noise in urban environments, mostly use battery-powered electric propulsion systems as power sources, not traditional propulsion systems such as reciprocating or turbine engines. Accordingly, certification preparation for the electric propulsion system and securing the safety of the electric propulsion system, are important issues. In the U.S., special technical standards equivalent to FAR Part 33 were issued to certify electric engines, and in Europe, various special conditions were established to certify electric propulsion systems. Thus, in Korea, the technical standards for the electric propulsion system for eVTOL aircraft must also be prepared in line with the U.S. and Europe. In this paper, SC E-19, the technical standard of the electric/hybrid propulsion system (EHPS) in special conditions, was analyzed. Additionally, securing the safety of the electric propulsion system of the aircraft are proposed, through the collaboration of SC E-19 technical standards with the existing aircraft safety evaluation procedure ARP 4761. Finally, through a case study of the Ehang 184 electric propulsion system, it has been confirmed that the proposed safety assurance method is applicable at the aircraft level.

• The Korean Journal of Air & Space Law and Policy
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• v.1
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• pp.87-123
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• 1989

The purpose of this thesis is to do a research on suppression of peacetime international terrorism and penal system of terrorists by political and economic means. International terrorism means wanton killing, hostage taking, hijacking, extortion or torture committed or threatened to be comitted against the innocent civilian in peacetime for political motives or purposes provided that international element is involved therein. This research is limited to international terrorism of political purposes in peacetime, especially, hijacking of civil aircraft. Hijacking of civil aircraft include most of international terrorism element in its criminal act and is considered to be typical of international terrorism in view of multinationality of its crews, passengers and transnational borders involved in aircraft hijacking. Civil air transportation of today is a indispensable part of international substructure, as it help connect continuously social cultural and economic network of world community by dealing with massive and swift transportation of passengers and all kinds of goods. Current frequent hijacking of civil aircraft downgrade the safety and trust of air travel by mass slaughter of passengers and massdestruction of goods and endanger indispensable substructure of world community. Considering these facts, aircraft hijacking of today poses the most serious threat and impact on world community. Therefore, among other thing, legal, political, diplomatic and economic sanctions should be imposed on aircraft hijacking. To pursue an effective research on this thesis aircraft hijacking by six Chineses on 5th May, 1983, from mainland China to Seoul, Korea, is chosen as main theme and the Republic of Korea's legal, political and diplomatic dealing and settlement of this hijacking incident along with six hijackers is reviewed to find out legal, political diplomatic means of suppression and solution of international terrorism. Research is focused on Chinese aircraft hijacking, Korea-China diplomatic negotiation, Korea's legal diplomatic handling and settlement of Tak Chang In, mastermind of aircraft hijacking and responses and position of three countries, Korea, China and Taiwan to this case is thoroughly analyzed through reviewing such materials as news reportings and comments of local and international mass media, Korea-China Memorandum, statements of governments of Korea, China and Taiwan, verdicts of courts of Korea, prosecution papers and oral argument by the defendants and lawyers and three antiaircraft hijacking conventions of Hague, Tokyo and Montreal and all the other instruments of international treaties necessary for the research. By using above-mentioned first-hand meterials as yardsticks, legal and political character of Chinese aircraft hijacking is analyzed and reviewed and close cooperation among sovereign states based on spirit of solidarity and strict observance of international treaties such as Hague, Tokyo and Montreal Conventions is suggested as a solution and suppressive means of international terrorism. The most important and indispensable factor in combating terrorism is, not to speak, the decisive and constant resolution and all-out effort of every country and close cooperation among sovereign states based on "international law of cooperation."

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.12
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• pp.1070-1079
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• 2012

The impact energy absorbing is a very important characteristic of an aircraft to enhance the survivability of occupants when an aircraft is under the survivable accident such as an emergency landing condition. The impact energy is generally transmitted into the occupant and absorbed through a landing gear, a subfloor (lower structure of fuselage), and a seat. The characteristic of crash energy absorbing of a subfloor depends on the type of an aircraft, a shape of structure, and an applied material. Therefore, the study of crashworthiness characteristics of a subfloor structure is very important work to improve the safety of an aircraft. In this study, a finite element model of a narrow body fuselage section for the 80~90 seats regional aircraft was developed and crash simulation was executed using an explicit finite element analysis. Through survey of the impact energy distribution of each structural part of a fuselage and floor-level acceleration response, the crashworthiness characteristics and performance was evaluated.

• The Korean Journal of Air & Space Law and Policy
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• v.33 no.1
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• pp.175-204
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• 2018

Recently, the aviation leisure business has been legislated, and related industries have become active base with increasing the light sports aircraft within the legislation system. However, in the light sports aircraft safety problem, it is often mentioned that the flight is in violation of the regulations, the lack of safety consciousness of the operator and lack of ability, and the personal operators have a risk of accident of light aircraft such as insufficient safety management and poor maintenance. At present, the maintenance of light sports aircraft is carried out by the A & P mechanic in accordance with the relevant laws and regulations, but it is difficult to say that it is equipped with qualification and expertise. It is not a legal issue to undertake light sports aircraft maintenance work on the regulation system. However, the problem of reliability and appropriateness is constantly being raised because airplanes, light sports aircraft, and ultra-light vehicle are classified and serviced in a legal method. Although legal and institutional frameworks for light sports aircraft are separated, much of it is stipulated in the aviation law provisions. Light sports aircraft maintenance work also follows the current aircraft maintenance system. In the United States, Europe, and Australia where General Aviation developed, legal and institutional devices related to maintenance of light aircraft were introduced, and specialized maintenance tasks are covered in the light aircraft mechanics system. As a result of analysis of domestic and foreign laws and regulations, it is necessary to introduce the qualification system for maintenance of light aircraft. In advanced aviation countries such as the United States, Europe, and Australia, a light sports aircraft repairman system is installed to perform safety management. This is to cope with changes in the operating environment of the new light sports aircraft. This study does not suggest the need for a light aircraft repairman system. From the viewpoint of the legal system, the examination of the relevant laws and regulations revealed that the supplementary part of the system is necessary. It is also require that the necessity of introduction is raised in comparison with overseas cases. Based on these results, it is necessary to introduce the system into the light aircraft repairman system, and suggestions for how to improve it are suggested.

• The Journal of Information Systems
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• v.8 no.2
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• pp.145-168
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• 1999

There are still occurring aviation accidents in spite of great preventing efforts all over the world. This paper contains some methods to prevent aircrafts deficiencies and accidents. First part of this paper refers to the background of those aviation deficiencies on mechanical, human and environment structures which influence directly to the air accidents and general survey on various theories of the aircraft's systems. On the way we discussed the general situations of the air tool's deficiencies which cause tragic accidents to the human lives and assets. After analysis on the situations we suggest the new systems which would forecast more detail accuracies concerned air elements for the safety flying. Then we introduce the following new systems resulting from the forecasting which can solve problems on aircraft deficiencies and complex interrelationships among air accidental factors. To simplify the complex systems, we needed to build the mechanical and organizational database for maintaining the procedures of the past troubleshooting on the major parts preventing deficiencies of those mechanical units. These suggested systems will contribute a great deal of aids, the maintenance credibility and air safety for the air operations and all customers in the world. Avoiding the past troubleshooting from just by using simple systems which can forecast main causes of the units and parts of the crafts, this system will be able to provide excellent management tools for the promoting aviational industries. The comfortable and convenient air operations are very valuable works, and the scientific method and detail maintenance will improve our daily air life by minimizing accidents. Adapting these developing systems, for the forecasting aircraft deficiencies and accidents can be integrated with the other aircraft management systems to promote more air safety in the world. This study is focused to eliminating aircraft accidents through forecasting deficiency symptom procedures by relational coordinations among all of the systems. Futhermore we need continuously detailed analysis and study for eliminating air accidents all together those who work in those fields.

• Journal of Aerospace System Engineering
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• v.14 no.spc
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• pp.7-12
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• 2020

In this paper the new revision of Korean Airworthiness Standards (KAS) - Emissions was proposed for enforced environmental standards. The Aircraft Engine Fuel Venting and Exhaust Emissions Requirements have been only defined for smoke, HC, CO and NOx as management items in previous KAS. However, this standard has not covered the current situation that International Civil Aviation Organization (ICAO) and United States Environmental Protection Agency (EPA) enforced environmental regulations, such as emissions trading system, limitation of CO₂ emissions and restriction of exhaust gas. In order to overcome these outdated situations, we presented the new requirements for aircraft exhaust gas emissions standard of Korea based on the latest standards of United States, Europe and other countries.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.233-241
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• 2021

As increasing the feasibility of the eVTOL UAM(electric vertical take-off and landing urban air mobility), numerous corporations and laboratories are conducting researches. In the aircraft development process, estimating the cost of the aircraft is essential part in terms of budgeting and commercial viability analysis. However, it is difficult to predict the cost of an eVTOL UAM owing to various configurations and little open cost information. This paper presents a novel method to predict the vehicle cost of various eVTOL configurations by modifying previous studies of the aircraft cost estimation. A vehicle cost of Wisk Cora is calculated by the presented method as an example to illuminate the method. The method is indirectly validated by comparing the vehicle costs of six representative eVTOL aircraft with those from the UAM study reports.

• 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.