• 한국기계가공학회지
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• 제18권7호
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• pp.90-96
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• 2019

Recently, friction stir welding of dissimilar materials are one of the biggest issues in terms of light-weight and eco-friendly technology of the automotive, aircraft and ship industry. In this study, friction stir welding of dissimilar materials is introduced with different tool rotational speed. Materials used in experimentation consist of A357 gravity cast aluminum alloy and FB590 high-strength steel plates. Dissimilar materials of plate type are fabricated with width of 150mm, length of 300mm and thickness of 3mm and welding is carried out by the lap joint method. The correlation between probe length and mechanical properties were investigated according to rotational speed and welding speed at tool tilt angle 0 degree. Consequently, feasibility of FSWed dissimilar materials were successfully presented in case of cast aluminum and high-strength steel at lap joint method.

• 한국항공우주학회지
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• 제50권6호
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• pp.377-384
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• 2022

복합재 항공기 구조물의 설계 시 인증을 고려한 재료 허용치와 설계치의 설정이 매우 중요하다. 그리고 복합재 구조물의 재료 허용치와 설계치의 설정은 정적강도, 손상허용 요구 조건 및 환경효과가 고려되어야 한다. 빌딩블록 접근법은 오랫동안 민간 및 군수 항공 산업에 적용되어 왔으며 중요한 인증 방법론을 제공하였다. 현재의 인증 방법은 시편, 요소, 부구성품 및 전기체 시험을 포함하는 광범위한 실험을 기반으로 한다. 본 논문에서는 복합재 허용치 실험 사례가 제시되며 빌딩 블록 접근 방식의 중요한 배경 및 적용방법이 제시된다.

• 한국항공운항학회지
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• 제30권4호
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• pp.132-144
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• 2022

In response to the recent surge in aviation demand, major airport and aviation authorities continue to make efforts to formulate arrival procedures that take into account efficient aircraft separation, noise and environmental issues related to carbon (CO₂) emissions. In order to ensure efficient traffic control and environmental issues, as a result, a new concept Trombone, Point Merge, etc. have been introduced and widely used. However, these new concept incisions are becoming a factor that hinders operational efficiency and stability due to the restricted domestic airspace such as military airspace and excessive constraints of altitude, speed, etc. which do not reflect the concept of continuous descent operation and eventually needs to be modified to make continuous descent operation as feasible as possible. We herewith analyze and propose the way of improving flight safety and efficiency in the arrival operation procedure by supplementary modification which consequently contribute to the aviation industry international competitiveness.

• 한국항공운항학회지
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• 제32권2호
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• pp.37-47
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• 2024

This paper examines the unique transportation challenges posed by Nepal's diverse and rugged terrain, which significantly hampers socio-economic development due to its negative impact on infrastructure, trade, and accessibility. Despite ongoing efforts to enhance road and traditional air transport systems, Nepal's geographic and environmental conditions continue to obstruct efficient connectivity, particularly in rural and remote areas. This study proposes Advanced Air Mobility (AAM) as a transformative solution, leveraging recent technological advancements in unmanned aerial vehicles (UAVs) and electric vertical takeoff and landing (eVTOL) aircraft. By conducting a comprehensive analysis of Nepal's current transportation infrastructure and the feasibility of AAM implementation, the paper highlights the potential benefits of AAM, including improved accessibility, economic growth, and environmental sustainability. Furthermore, it addresses the anticipated challenges and regulatory considerations necessary for integrating AAM into Nepal's transportation network. Through a multidisciplinary approach, this research aims to contribute to the discourse on overcoming transportation barriers in mountainous regions, offering policy recommendations and identifying areas for future study to facilitate the adoption of AAM in Nepal and similar contexts worldwide.

• 한국해양공학회지
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• 제24권2호
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• pp.57-61
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• 2010

At present, welding technology is not only emphasized in the development of manufacturing technology but its application is also expanding. In these systems, attempts have been made to use SUS as a high-temperature material for special applications, and in improvements in manufacturing technologies bear watching, together with an increase in the use rate. Specifically, three-dimensional wings are often used for fasteners with the purpose of decreasing the weight (정해용, 2007). However, due to developments in welding technology, there has been a recent tendency to replace existing assembly methods with welding. Specifically, if laser welding techniques are applied, the heat-affected zone can be minimized compared toother welding techniques. However, in the case of these special welding techniques, there is an increase in residual stress, which fatally affects the fatigue life. In order to remove the residual stress and its effect on fatigue life, shot-peening is executed. The intention of this study was to obtain the optimal conditions for shot-peening.

• 한국기계가공학회지
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• 제6권3호
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• pp.98-104
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• 2007

The carbon fiber reinforced carbon composite (CFRC) materials are necessary for the advanced industries that require the thermal resistance. And the development and research for CFRC has been in progress in the field of aerospace and defense industry. CFRC have several advantages and special properties such as excellent anti ablation, outstanding strength retention at very high temperature, high heat capacity and thermal transport, high specific stiffness and strength, and high thermal shock resistance. They have been used as aircraft brake, rocket nozzle, nose cones, jet engine turbine wheels, and high speed craft. Since the technology related to CFRC was prohibited from importing and exporting, we developed our own technology to produce F-16 B32 brake disk made out of CFRC, and then we performed various tests to observe the characteristics of CFRC-based brake disk developed in this study in view of density, strength, friction, specific heat, and heat conductivity.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2002년도 추계공동학술대회
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• pp.199-204
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• 2002

보전에 중점을 둔 신뢰성(RCM)은 1960년대 후반 상업용 항공기산업을 위해 개발되었고, 현재는 항공기 이외의 여러 장치에도 적용되고 있다. RCM은 예방보전계획을 수립하기 위한 방법으로 예방보전계획은 장치와 구조물의 안전성과 가동성 수준을 효율적이고 효과적으로 성취하게 한다. RCM은 장치와 구조물에 적용가능하면서 효율적인 예방보전요구를 확인하기 위해 결정논리나무를 사용한다. 결정논리를 통하여 보전작업의 실행 필요성에 대하여 최종적으로 판단한다. 본 연구에서는 IEC 60300-3-11을 중심으로 기기나 장치에 대한 RCM분석방법 및 운용방법에 대한 지침을 제공하고자 한다.

• 한국산업융합학회 논문집
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• 제26권5호
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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.

• 한국항행학회논문지
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• 제28권4호
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• pp.472-479
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• 2024

세계 전체인구의 절반이 도시에 거주하고 있고, 지속적인 도시화가 진행되고 있으며 2050년 경에는 도시인구가 전체 인구의 2/3를 초과할 것으로 예상하고 있다. 이러한 현상을 해소하기 위해 우리나라 정부에서는 새로운 도심 항공 모빌리티(UAM; urban air mobility) 산업 생태계 구축에 심혈을 기울이고 있다. 항공사 또한 UAM 산업 생태계에 속해 있으며 안전운항, 승객의 안전, 기재 운영 효율성, 정시성 등의 효율성 제고에 대한 준비를 하고 있다. 본 연구는 2019년부터 2023년까지 대한항공의 김포발 제주행 노선의 일일 승객 수에 대한 시계열 데이터를 활용하여 수요 예측을 수행한다. 이를 위해 SARIMA, Prophet, CatBoost, Random Forest와 같은 통계적 및 기계 학습 모델을 적용한다. 다양한 모델을 통해 승객 수요 패턴을 효과적으로 포착할 수 있는 방법을 평가하였고, 머신러닝 기반의 Random Forest 모델이 가장 뛰어난 예측 결과를 나타냈다. 연구 결과는 항공 산업에서 정확한 수요 예측을 위한 최적의 모델을 제시하여 운영 계획 및 자원 할당에 필요한 기초정보를 제공할 것이다.

• 동력기계공학회지
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• 제6권1호
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• pp.68-73
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• 2002

An opportunity to use the elevated temperature has been recently increasing in various elements of heat facilities or machines such as heat exchanger tubes, pressure vessels, engines of aircraft, boilers and turbines in power plants, and nuclear reactor components, etc. as machinery industry develops. Thus, the development of such elevated-temperature heat-resisting materials and the studies on their elevated-temperature materials friction welding, creep design and analysis have been considered as an important and needful fact. In this paper, friction welding optimization for 1Cr0.5Mo to STS304 and AE applications for the weld quality evaluation were investigated. The important results of this study are as follows : The techniques for dissimilar friction welding optimization of the elevated temperature materials 1Cr0.5Mo and STS304 and its real-time weld quality evaluation by AE were developed, considering on both strength and toughness. Quantitative relationship was identified among welding condition, weld quality and cumulative AE counts.