• Structural Engineering and Mechanics
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• v.85 no.1
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• pp.1-14
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• 2023

The use of functionally graded materials in applications involving severe thermal gradients is quickly gaining acceptance in the composite mechanics community, the aerospace and aircraft industry. In the present study, a refined sandwich plate model is applied to study the free vibration analysis of porous functionally graded material (FGM) sandwich plates with various distribution rate of porosity. Two types of common FG sandwich plates are considered. The first sandwich plate is composed of two FG material (FGM) face sheets and a homogeneous ceramic or metal core. The second one consists of two homogeneous fully metal and ceramic face sheets at the top and bottom, respectively, and a FGM core. The displacement field of the present theory is chosen based on nonlinear variations in the in-plane displacements through the thickness of the sandwich plate. The number of unknowns and equations of motion of the present theory is reduced and hence makes them simple to use. In the analysis, the equation of motion for simply supported sandwich plates is obtained using Hamilton's principle. In order to present the effect of the variation of the porosity distribution on the dynamic behavior of the FGM sandwich plates, new mixtures are proposed which take into account different rate of porosity distribution between the ceramic and the metal. The present method is applicable to study the dynamic behavior of FGM plates and sandwich plates. The frequencies of two kinds of FGM sandwich structures are analyzed and discussed. Several numerical results have been compared with the ones available in the literature.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.5
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• pp.303-310
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• 2023

β titanium alloys are widely used in aerospace industry due to their excellent specific strength and corrosion resistance. In particular, mechanical properties of metastable β titanium can efficiently be controlled by various deformation mechanisms such as slip, twinning, and SIM (Stress-Induced Martensite Transformation), making it an ideal material for many industrial applications. In this study, Ti-5Mo-xFe (x=1, 2, 4 wt%) alloy was designed by adding a relatively inexpensive β element to ensure price competitiveness. Additionally, microstructural analysis was conducted using OM, SEM, and XRD, while mechanical properties were evaluated through hardness and compression tests to consider the deformation mechanisms based on the Fe content. SIMT occurred in all three alloys and was influenced by the presence of β_m (metastable beta) and beta stability. As the Fe content decreased, the α'' phase increased due to SIMT occurring within the β_m phase, resulting in softening. Conversely, as the Fe content increased, the strength of the alloy increased due to a reduction in α'' formation and the contributions of solid solution strengthening and grain strengthening. Moreover, unlike the other alloys, shear bands were observed only in the fracture of the Ti-5Mo-4Fe alloy, which was attributed to differences in texture and microstructure.

• The Journal of Economics, Marketing and Management
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• v.6 no.4
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• pp.1-16
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• 2018

Purpose - This study will investigate and identify the relationship between brand image, brand attitude and intent to purchase based on subjects that have remembered or watched more than one storytelling marketing ad related to airlines. The purpose of the project is to secure market competitiveness by presenting the basis for and use of the marketing strategy using storytelling, which can capture the goodwill of the aerospace competition market in the future. Research, design, data, and methodology - Prior to the research model and hypothesis testing phase, a verification factor analysis was conducted to assess internal consistency among each measurement item and to ensure reliability and validity of the measurement tool. Further, the organization was assessed for validity by calculating the mean variance estimation (AVE) and the construction concept reliability (CCR) through a positive factor analysis. Hypothesis verification was analyzed through a structural equation model, and each concept set in the hypothesis was entered as a potential variable, and each measurement item was entered as an observation variable. Results - Airline's storytelling marketing has a significant impact on the brand image and two emotional and cognitive responses have been shown to influence the brand image. In addition, airline storytelling marketing has a significant impact on brand attitudes and airline storytelling marketing derived from factor analysis has shown two emotional and cognitive responses to brand attitudes. Conclusions - The parts derived based on the research results show that storytelling marketing has a strong influence on the airline's brand image and attitude, and that it is necessary for airlines to have a brand image and attitude. Also, forming a favorable brand image has a significant impact on brand attitudes. We believe that by presenting basic data to the aviation industry in future research on airline storytelling, we will be able to increase understanding and contribution to development of storytelling marketing in aviation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.457-464
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• 2006

Fiber-reinforced composite materials due to their high specific strength, high stiffness and light weight are becoming increasingly used in many engineering industry, especially in the aerospace, marin and civil, etc. In this paper, the buckling load and mode shapes of composite laminates with elliptical cross-section including transverse shear deformations are analyzed. For solving this problems, a versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. Also, an improved shell element has been established by the combined use of the addition of enhanced assumed strain and the substitute shear strain fields. The combined influence of shell geometry and elliptical cross-sectional parameter, fiber angle, and lay-up on the buckling loads of elliptical cylinder is examined. The critical buckling loads and mode shapes analyzed here may serve as a benchmark for future investigations.

• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.649-657
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• 2023

ICAO adopted the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) at the 39th General Assembly in 2016, and 115 countries, including South Korea, expressed their intention to participate in CORSIA as of January 1, 2023. Since carbon generated in the aviation industry is mainly caused by greenhouse gases emitted from aircraft engines, fuel consumption must be reduced to reduce carbon emissions. Prior research, such as simulation, is essential to predict the effectiveness of each plan and to make decisions about its implementation. High-quality data is needed to derive accurate results, but it has been difficult to secure actual fuel consumption data, as they are considered to be classified airline data. Therefore, in this paper, after establishing a model that estimates fuel consumption based on actual fuel consumption data, the model is to be advanced to improve its accuracy.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.733-739
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• 2023

The purpose of this study verify to the effect of applying the X-ray screening ability rating for security screening persons in Incheon International Airport. Data collected through a evaluation score of 1,034 security screening persons in Incheon International Airport. Data analysis performed using paired sample t-test. The research results found that it was a statistically significant difference pre-test and post-test applying the X-ray screening ability rating. In this article, we asserts that the X-ray screening ability rating is effective in improving the X-ray screening ability of security screening persons. This paper contribute to the academic expansion of motivation theory and self-determination theory. This study is valuable as a preemptive empirical research that provides practical implications about the application of X-ray screening ability rating for security screening persons.

• Journal of Advanced Navigation Technology
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• v.27 no.6
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• pp.804-814
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• 2023

Various buildings are scattered below and around the flight path of UAM (Urban Air Mobility), which flies within a densely populated urban area. And the vertiport used by UAM for takeoff and landing is located on a flat area within the city center or on top of a building. As such, UAM operates in densely populated urban areas, and vertiports for takeoff and landing are installed in densely populated areas, requiring a very high level of safety. In particular, for safe landing of UAM, it is necessary to monitor the approach status of UAM approaching the vertiport from the final approach course and provide approach information. Accordingly, to monitor the UAM vertiport final approach path, research was conducted on technology that utilizes optical equipment that can be installed in a narrow site and has the advantage of reducing the burden of electromagnetic waves.

• Nuclear Engineering and Technology
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• v.56 no.9
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• pp.3585-3593
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• 2024

Radioisotopes tend to play important roles in many fields, such as industry, healthcare, agriculture, aerospace, etc. Radioisotope production is mainly through accelerators or research reactors, and high flux research reactor is one of the most effective approaches for radioisotope production. The physical basis of preparing radioisotope relies on nuclear reactions occurring in the reactor core, which includes fission, (n,γ), (n,α), and (n,p) reaction, etc. Among them, fission and (n,γ) reaction are most important in the nuclear reactor. For example, the ⁹⁹Mo could be generated by uranium fission and extracting from the fission products, or through the radiative capture reaction from enriched ⁹⁸Mo. As for the fission method, the irradiation target is gradually transitioning from high enriched uranium (HEU) target to low enriched uranium (LEU) target due to the requirement of non-proliferation. In this paper, studies on the impacts of different fission targets on radioisotope productions are conducted. Moreover, an optimized study on the radiative capture method is performed to improve the production efficiency. It is concluded that it is advantageous to use radiative capture method to generate radioisotopes in high flux reactor, which helps to improve the specific activity with environmental friendliness.

• The Korean Journal of Air & Space Law and Policy
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• v.30 no.1
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• pp.151-180
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• 2015

South Korea is advancing the unmanned aircraft private commercial business. Unmanned aerial vehciles industry has been developing for several years also abroad. However, unmanned aerial vehciles industry, can be an accident occurs. Accident of unmanned aerial vehciles to occur material damage and casualties. Particularly if an accident because of a defect in the unmanned aerial vehciles has occurred, it is necessary to analyze the liability for this. The defect accidents unmanned aerial vehciles has been the different manufacturing and design product is intended, whether it is important how to prove to this. This is because, unmanned aerial vehciles are designed in any intent of the original, it is impossible to victims know. So imposing a responsibility to prove the design by the manufacturer intended consumer is not fair. Moreover, the consumer, it is necessary to prove only that the product is one that normally dangerous lacked safety can be expected. This is a detailed issue of judgment of defects of unmanned aerial vehciles, the manufacturer to bear the accountability. In the case where the defect on the display of the unmanned aircraft is a problem, and if it reasonable indication, it is not appropriate to be required to prove that it was possible to prevent damage to the victim.

• Journal of Distribution Science
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• v.14 no.5
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• pp.51-57
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• 2016

Purpose - In the year of 2015 and 2016, one of the items that got attention in CES was a drone. It has been 100 years since a drone emerged, but most were used for military purposes. As its use became diverse as of 2010, it got attention of the general public. In Korea, it was in 2011 that a drone was known to the public through an aerial video shooting for television program. This study tried to come up with suggestions by comparing domestic with overseas cases, and tried to consider the related technologies and systems with applying the role of drones in logistics service. Research design, data, and methodology - The overseas cases were regarded as drone's logistical purpose. The Prime Air service by US Amazon is still not commercialized and under pre-testing due to Federal Aviation Regulations, although it started in 2013. In Germany, DHL succeeded in delivering service testing which is called Parcelcopter, but it is not commercialized yet. Other than these, there are more attempts to prepare logistics service in China with Taobao, in France with Geopost's test, and in Africa. In Korea, CJ Korea Express tested delivery with a self-developed drone Results - In order to study for utilizing drones for logistics as the prerequisites, some overseas and domestic cases, which are currently considered, were reviewed. Also, the technologies and institutional requirements to commercialize drones for logistical purpose were reviewed. The reasons for using drones in logistics is to ensure the price competitiveness by reducing cost. The empirical test also will be needed because drone pilot areas are designated by ministry of land, infrastructure and transport. Conclusions - In order to utilize drones in logistics and foster the industry, this study would like to suggest the followings. First of all, size of drones for logistics needs to be fixed and their operating system should be standardized. Centralized investment resources are needed through standardization to ensure the market occupancy. Secondly, it is necessary to get the converged businesses that do research, develop and commercialize drones with the investment of private sector. Example can be found in Korea aerospace Industries. We can respond to the rapid growth of the market with intensive investing by integrating the private sector investment. Thirdly, institutional arrangements are needed to be established quickly. In the case of high-technologies like drones, institutional support often does not follow the rapid development of the technology. The problems can be found in securing drones-only airspace, creating drone-specialized pilot's license, matters related to remote controller and complementary regulations for drones in Aviation Act. If these regulations are not prepared or complemented at the right timing, technologies cannot be commercialized even though the development is completed. Fourthly, there is a need to secure the transparency regarding possible privacy and personal information protection problem while operating drones. Finally, in order to foster this new industry, government should focus on supporting R&D more in the long term than short term outcomes.