• Journal of the Korean association of regional geographers
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• v.19 no.1
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• pp.1-13
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• 2013

Damyang Wetland Reserve with $980,575m^2$ area is located in Damyang-gun, Jeonlanam-do and Buk-gu, Gwangju Metropolitan City. The purpose of this paper is to divide Damyang riverine wetland into several geomorphic units, to analyze their sediments, and to categorize small ecosystem units composing riverine wetland. Riverine wetlands are classified into three types such as riverbed-, floodplain-, and abandoned-channel-wetland, and Damyang riverine wetland belongs to riverbed-wetland type. In this paper to categorize small geomorphic units of riverine wetland, we divide small geomorphic units from aircraft images analysis, and modify and supplement them following field survey results. Damyang Wetland Reserve is categorized into 22 ecosystem units. That physical and chemical properties of their sediments are different spatially, implicate that inorganic environment of Damyang riverine wetland ecosystem is very extensive. On the basis of the results of this study, policymakers will be able to design a strategy which manage Damyang Riverine Wetland Reserve more effectively, and for them interdisciplinary researches on relationships between various fluvial landforms and various lifeforms inhabiting them in Damyang Riverine Wetland Reserve are required.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.541-549
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• 2008

The fatigue analysis is performed to avoid structural failure in aerospace structures under repeated loads. In this paper, the fatigue life is estimated for the design of tilt rotor UAV. First of all, the fatigue load spectrum for tilt rotor UAV is generated. Fatigue analysis is done for the flaperon joint which may have FCL(fracture critical location). Tilt rotor UAV operates at two modes: helicopter mode such as taking off and landing; fixed wing mode like cruising. To make overall fatigue load spectrum, FELIX is used for helicopter mode and TWIST is used for fixed wing mode. The other hand, the Kriging meta model is used to get S-N regression curve for whole range of material life when S-N test data are analyzed. And then, the second order of S-N curve is accomplished by the least square method. In addition, the coefficient of determination method is used to ensure how accuracy it has. Finally, the fatigue life of flaperon joint is compared with that obtained by MSC. Fatigue.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.389-397
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• 2018

Modern countries have almost ratified the UN Convention on the rights of persons with disabilities and are creating environments to prevent discrimination against these individuals. In 1996, the International Maritime Organization presented a recommendation for the design and operation of passenger ships to respond to elderly and disabled persons' needs. In Korea, an act on the promotion of transportation convenience for mobility disadvantaged persons has been implemented, and facilities for the disabled have been rapidly installed in ships, vehicles, aircraft, railways and passenger terminals. However, the maritime transport environment is less concerned about disabled persons than safety. In this study, basic research was conducted to improve the maritime transport environment for disabled people in Korea through a field survey and literature survey. As a result, it was found that relevant laws and regulations have not been properly applied to excursion ships and ferries as well as small-scale ports, which are responsible for a large part of coastal passenger transportation. In addition to low installation rates of facilities for the transportation of persons with disabilities in ships and terminals, loose equipment was also considered. Therefore, it is necessary to protect the human rights of persons with disabilities, which are universal values of humanity, by complementing laws and introducing improved facilities.

• Composites Research
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• v.34 no.5
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• pp.296-304
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• 2021

This study presented the evaluation of the stamp forming process for L-shape CF/PEKK thermoplastic composite using the finite element model. The formability of three different trimming allowances has been examined for representative product geometry. The results showed that those manufactured by high trimming allowance showed more excellent formability in those areas. Moreover, the effects of the trimming allowances on the stress, thickness, wrinkle distributions of thermoplastic composites fabricated with the stamp forming process were evaluated. The comparison of the simulation and experimental results for the thickness and wrinkle distributions proved the accuracy of the stamp forming model. The crystallinity of the composite was performed by differential scanning calorimetry (DSC). The void content of the composite was evaluated by matrix digestion. Then, the fabricated structure was characterized and achieved high quality in crystallinity and void content. Consequently, the presented FEM modeling shows excellent potential for application in the aircraft product design process. This pragmatic approach could efficiently offer a valuable solution for the thermoplastic composite manufacturing field.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.8-14
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• 2019

Bird-strike is one of the most important design factors for safety in the aviation industry. Bird-strikes have been the cause of significant damage to aircraft and rotorcraft structures and the loss of life. This study used DYTRAN software to simulate the transient response of an Euler-Lagrangian composite helicopter blade that has been impacted by a bird. The Arbitrary Lagrangian Eulerian (ALE) method and a suitable equation of state were applied to model the bird. ALE was applied to the bird-strike analysis due to the large difference between the properties of the blade and bird. The debris of the bird was assumed to be a fluid and applied as Euler elements after the collision. Through the analysis of bird impacts, the leading-edge of the rotor blade (50.8 mm) was used to identify a positive margin of 1.18 based on the TSAI-FILL criteria. The results are assessed to be sufficiently reliable and may be evaluated to replace tests with various analysis conditions. The structural stability of the rotor blade could be assessed by applying various load conditions and different modeling methods in the future.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.23-31
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• 2018

In the present work, the thrust and torque of multicopter propellers in hovering are predicted based on BET method. The geometry information of the propellers is obtained using a three dimensional scanner and the airfoil section is extracted using CATIA. EDISON CFD is adopted to calculate the drag and lift of airfoil at a given geometry and flow conditions and then thrust is calculated with respect to a given RPMs based on BET. Two simulations with laminar and turbulent flows are considered. The predicted value is compared with the performance data from the Product Company and results from JavaProp software, which is used in the design and prediction of propellers. In the case of a 9-inch propeller, the thrust from the product company is corresponding to the results between the laminar and turbulent flow conditions. In the 16-inch case, the predicted thrust at turbulent flow conditions conformed well with reference one. The predicted torque shows a big difference with the reference data.

• The Journal of the Acoustical Society of Korea
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• v.43 no.1
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• pp.103-111
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• 2024

Axial-flow fans are used to transport fluids in relatively low-pressure flow regimes, and a variety of design variables are employed. The tip geometry of an axial fan plays a dominant role in its flow and noise performance, and two of the most prominent flow phenomena are the tip vortex and the tip leakage vortex that occur at the tip of the blade. Various studies have been conducted to control these three-dimensional flow structures, and winglet geometries have been developed in the aircraft field to suppress wingtip vortices and increase efficiency. In this study, a numerical and experimental study was conducted to analyze the effect of winglet geometry applied to an axial fan blade for an air conditioner outdoor unit. The unsteady Reynolds-Averaged Navier-Stokes (RANS) equation and the FfocwsWilliams and Hawkings (FW-H) equation were numerically solved based on computational fluid dynamics techniques to analyze the three-dimensional flow structure and flow noise numerically, and the validity of the numerical method was verified by comparison with experimental results. The differences in the formation of tip vortex and tip leakage vortex depending on the winglet geometry were compared through a three-dimensional flow field, and the resulting aerodynamic performance was quantitatively compared. In addition, the effect of winglet geometry on flow noise was evaluated by numerically simulating noise based on the predicted flow field. A prototype of the target fan model was built, and flow and noise experiments were conducted to evaluate the actual performance quantitatively.

• The Korean Journal of Air & Space Law and Policy
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• v.27 no.2
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• pp.67-106
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• 2012

Today air traffic at the airport is complicated including a significant increase in the volume of air transport, so aviation accidents are constantly occurring. Therefore, we should newly recognize importance of the Air Traffic Safety, the core values of the Air Traffic. The location of airport that is the basic infrastructure of the air traffic and the security of safety for facilities and equipments are more important than what you can. From this dimension, I analyze the step-by-step safety factors that are taken into account in the airport development projects from the construction or improvement of the airport within the current laws and institutions and give my opinion on the enhancement of safety in the design and construction of airport. The safety of air traffic, as well as airport, depends on location, development, design, construction, inspection and management of the airport including airport facilities because we have to carry out the national responsibility that prevents the risk of large social overhead capital for many and unspecified persons in modern society through legislation regarding intervention of specialists and locational criteria for aviation safety from the planning stage of airport development. In addition, well-defined installation standards of airports and air navigation facilities, the key points of the airport development phase, can ensure the safety of the airport and airport facilities. Of course, the installation standards of airport and air navigation facilities are based on the global standard due to the nature of air traffic. However, to prevent the chaos for the safety standards in design, construction, inspection of them and to ensure the aviation safety, the safety standards must be further subdivided in the course of domestic legislation. The criteria for installation of the Air Navigation facilities is regulated most specifically. However, to ensure the safety of the operation for Air Navigation Facilities, performance system proved suitable for the Safety of Air Navigation Facilities must change over from arbitrary restrictions to mandatory restrictions and be applied for foreign producers as well as domestic producers. Of course, negligence of pilots and defective aircraft maintenance lead to a large portion of the aviation accidents. However, I think that air traffic accidents can be reduced if the airport or airport facility is perfect enough to ensure the safety. Therefore, legal and institutional supplement to prioritize the aviation safety from the stage of airport development may be necessary.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.8
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• pp.759-769
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• 2013

Electronic equipment has been applied to virtually every area associated with commercial, industrial, and military applications. Specifically, electronics have been incorporated into avionics components installed in aircraft. This equipment is exposed to dynamic loads such as vibration, shock, and acceleration. Especially, avionics components installed in a helicopter are subjected to simultaneous sine and random base excitations. These are denoted as sine on random vibrations according to MIL-STD-810F, Method 514.5. In the past, isolators have been applied to avionics components to reduce vibration and shock. However, an isolator applied to an avionics component installed in a helicopter can amplify the vibration magnitude, and damage the chassis, circuit card assembly, and the isolator itself via resonance at low-frequency sinusoidal vibrations. The objective of this study is to investigate the dynamic characteristics of an avionics component installed in a helicopter and the structural dynamic modification of its tray plate without an isolator using both a finite element analysis and experiments. The structure is optimized by dynamic loads that are selected by comparing the vibration, shock, and acceleration loads using vibration and shock response spectra. A finite element model(FEM) was constructed using a simplified geometry and valid element types that reflect the dynamic characteristics. The FEM was verified by an experimental modal analysis. Design parameters were extracted and selected to modify the structural dynamics using topology optimization, and design of experiments(DOE). A prototype of a modified model was constructed and its feasibility was evaluated using an FEM and a performance test.