• Journal of Power Electronics
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• v.18 no.4
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• pp.1255-1267
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• 2018

Parasitic parameters have a larger influence on Silicon Carbide (SiC) devices with an increase of the switching frequency. This limits full utilization of the performance advantages of the low switching losses in high frequency applications. By combining a theoretical analysis with a experimental parametric study, a mathematic model considering the parasitic inductance and parasitic capacitance is developed for the basic switching circuit of a SiC MOSFET. The main factors affecting the switching characteristics are explored. Moreover, a fast-switching double pulse test platform is built to measure the individual influences of each parasitic parameters on the switching characteristics. In addition, guidelines are revealed through experimental results. Due to the limits of the practical layout in the high-speed switching circuits of SiC devices, the matching relations are developed and an optimized layout design method for the parasitic inductance is proposed under a constant length of the switching loop. The design criteria are concluded based on the impact of the parasitic parameters. This provides guidelines for layout design considerations of SiC-based high-speed switching circuits.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.3
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• pp.303-308
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• 2014

Aircraft are an indispensable mode of modern transportation. They are also used as in a wide variety of other fields. For example, aircraft are used for accommodating passengers, carrying freight, and for military reconnaissance. Aircraft ground operations include landing and taking off. During landing, a higher load is applied to the landing gear than during takeoff. The landing gear should absorb impact energy and prevent damage to the main body of the aircraft in the case of an accident. In this study, simulations were performed for two types of plate-spring-type landing gear: that made of composite materials and that constructed with aluminum. The structural safety of landing gear made of each material was also evaluated.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.26 no.2
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• pp.132-138
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• 2018

Aviation safety requires systematic national attention and management because aircraft accident produce greater undesired social impact, economical damage, and declining national credibility compare to other transportation accident. Specially, Republic of Korea has highly increased risk of air accident as a major air transportation point having small aerospace, connecting pacific ocean and Asia, and explosively increased air traffic produced by economical growth, operating numerous military aircraft for the South and North Koreas' confrontational situation. Also, greatly increased domestic and oversea air travels by Koreans and foreigners as well as air freight based on heightened Korea's national power, launching new low cost carriers, and popularized leasure aviation have produced large amount of aviation needs in various fields. However, national aviation safety management system gratifying increased aviation needs and aircraft operations is seem to be slow in progress. This paper will show optimized measures utilizing private, governmental, and military resources to prevent aircraft accident under circumstances of limited budget and an favorable conditions, then will propose several action items.

• Journal of Environmental Science International
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• v.23 no.12
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• pp.2089-2099
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• 2014

Emissions from aircraft have impacts on the air pollution of airport and the surrounding area. There are methods of emissions calculated as Tier 1, Tier2, Tier 3A and Tier 3B. Thus, this study investigated emissions from aircraft at the Gimhae International Airport using EDMS(Emissions & Dispersion Modeling System) program. Results of estimation from aviation emissions, Tier 3B considering all parts which can occur at the airport has the largest amount emissions. In order to understand the relation between aviation emissions and distribution of ozone concentration over airport area, numerical evaluation were carried out. Although the difference of surface ozone distribution between numerical assessment with and without aviation emissions was little, effects of air pollution at airport area from aviation emissions of NOx and VOCs.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.3
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• pp.50-59
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• 2014

It has been focused on that the major reasons of aircraft accidents resulted not from human error but from the failure of teamwork or communication in 1980's. Such opinions were suggested in the workshop, so called, "Resource Management on the Flight Deck" by NASA in 1979. The researchers agreed the fact the source of human error was originated from the failure in teamwork, communication or even in leadership of captain. Due to the rapid development of aircraft technologies, the reasons for aircraft accident could be easily found out. According to the analysis results of the technology, most of reasons for the accident might directly be connected not to human error or stick-Rudder skill but to situational awareness, communication, leadership or decision making in the aircraft. This paper has tried to research empirically the satisfaction of flight crews who have gone thorugh CRM training in the commercial airline. Based on the quantitative scale by J. Ford et al. (2014), this paper has proved which characteristics of CRM training has a positive impact on the overall satisfaction of CRM training. It was proven that the teamwork and decision making programs among CRM training have a major effect to the satisfaction level of flight crews.

• Journal of Aerospace System Engineering
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• v.13 no.5
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• pp.24-31
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• 2019

In this study, we analyzed the cause of the burn out phenomenon in the power distribution system for aircraft and proposed the improvement method. The power distribution device for aircraft has an AC and DC, and there is a rectifier between the two devices. The capacitors in the power board burn out when the power is turned on and off. The main reason for this is the excessive voltage caused by the inductance built into the rectifier. The cases that can cause a failure are classified. The impact was analyzed and the solution was established through the experimental method.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.6
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• pp.607-614
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• 2015

In this paper, structural analysis for the 16 core competencies of aircraft maintenance crew using FSM is carried out for the purpose of improving the capability of aircraft maintenance. As a result, the three groups of layers are composed of the 3 top layers, 3 middle layers and 10 lowest layers. These results make it possible to grasp the impact and importance. In addition, the core competency of aircraft maintenance crew can improve the maintenance quality and productivity through working on the spot. In this viewpoint, fuzzy relational matrix, which is used as a basis for evaluating the work, can be obtained from the data of the 100 aircraft maintenance crew for core competencies. In this paper, the efficiency of this model is shown by utilizing the 100 modeling data and the 67 checking data.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.12 no.2
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• pp.29-42
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• 2004

This paper performs a historical review on aviation threats through a statistical survey. The impact factor, as a criterion to measure the seriousness of the threats occurred, is introduced and evaluated based on annual totals of hijacking and fatalities against aircraft 1948 through 2004. Also, the paper suggests processes of evaluating the level of threats and key functions for an effective management of the aviation security.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2105-2113
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• 1995

The compressive tests under impact conditions were performed to establish a design guide for impact damage tolerance. The composition of layup was selected for the real cases of composite aircraft structure. The energy level of visible of visible damage threshold was determined as 7 Joules. It was found that the normalized bending stiffnesses in the direction of closely fixed boundary affected the area of damage. Graphite/epoxy used in the tests exhibited 60% reduction in compression strength at the energy level of visible damage threshold. Wet-conditioned specimens represented 9% reduction in residual compressive strength in comparison with room temperature ambient specimens. In this study, a design factor of 2.1 was proposed for the low velocity impact damage.

• International Journal of Advanced Culture Technology
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• v.11 no.2
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• pp.381-388
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• 2023

Small-scale environmental impact assessments have limitations in terms of survey duration and evaluation resources, which can hinder the assessment and analysis of the current situation. In this study, we propose the use of drone technology during the environmental impact assessment process to supplement these limitations in the current situation analysis. Drone photography can provide rapid and accurate high-resolution images, allowing for the collection of various information about the target area. This information can include different types of data such as terrain, vegetation, landscape, and real-time 3D spatial information, which can be collected and processed using GIS software to understand and analyze the environmental conditions. In this study, we confirmed that terrain and vegetation analysis and prediction of the target area using drone photography and GIS analysis software is possible, providing useful information for environmental impact assessments.