• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.697-702
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• 2010

A WIG(Wing-In-Ground effect) craft flies close to the water surface by utilizing a cushion of relatively high pressurized air between its wing and water surface. This implies that when one designs such craft it is important to have lightweight structures with adequate strength to resist external loads with some margins. To investigate this requirement, this paper deals with the structural analysis of the bottom plate of small WIG craft having a design landing weight of 1.2-ton. As building materials for the WIG craft, pre-preg carbon/epoxy composites are considered. The strength information of the bottom plate is obtained using the first-ply-failure analysis in conjunction with a mid-plane symmetric laminated plate theory. As a result, the first-ply-failure location, load and deflection of the bottom plate are obtained. The calculated strength information is compared with the water reaction load for the bottom plate of seaplanes considered when they land on the water surface -the same fluid-structure interaction mechanism as that of WIG craft. In the calculation of seaplane water reaction load information, the rules shown in FAR(Federal Aviation Regulations) Part 25 are used. Through the comparison, the structural integrity of the bottom plate for the WIG craft is checked.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.6
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• pp.422-428
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• 2019

A tailless or Blended-Wing-Body(BWB) shaped configuration is highlighted for UCAV with low RCS characteristics. The BWB configuration is characterized by its directional static instability and low controllability. To control the directional movement of the BWB configured vehicle, directional thrust vectoring equipment or drag rudder typed control surfaces which utilize the drag differences of the wing can be considered. This paper deals with a BWB shaped configuration using a spoiler and describes the lateral-directional aerodynamic characteristics of the vehicle. In addition, it is shwon that the lateral-directional motion can be controlled effectively by using the classical PI control structure. This control law is verified by flight test and showed adequate for the tailless BWB shaped UAV.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.269-273
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• 2023

Based on the K-UAM roadmap, this study was conducted to select major education and training subjects necessary for the composition of the initial UAM pilot education and training curriculum. Currently, UAM aircraft have similar characteristics to rotorcraft that can take off and land vertically around VTOL functions. Therefore, in this study, the Rotary Wing Pilot Training Curriculum of the Army Aviation School, which represents Rotary Wing Flight Education, was selected as a comparative group, and education and training subjects for initial UAM pilot training were selected. First, a hierarchical structure for the AHP survey was designed based on the Army's rotorcraft pilot education and training subjects, and the AHP survey was conducted by selecting experts from each class. If the education and training subjects given as priorities through AHP analysis are applied to initial UAM pilot training, it is expected to contribute to the effect of education and training and ultimately to the safe operation of UAM.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.87.2-87.2
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• 2013

We studied a fine-scale half ring-like structure around a pore seen from the high spectral and the high spatial resolution data. Our observations were carried out using the Fast Imaging Solar Spectrograph (FISS) and the InfraRed Imaging Magnetograph (IRIM) installed at the 1.6 meter New Solar Telescope of Big Bear Solar Observatory (BBSO) on 2012 July 19. During the observations, we found a fine-scale half ring-like structure located very close to a pore (~0.4 arcsec apart from the pore). It was seen in the far wing images of the $H{\alpha}$ and Ca II $8542{\AA}$ lines, but it was not seen in the line center images of two lines. The length of the structure is about 4200 km and the width is about 350 km. We determined its line-of-sight velocity using the Doppler shift of the centroid of the Ti II line ($6559.6{\AA}$, close to the $H{\alpha}$ line) and determined horizontal velocity using the NAVE method. we also investigated the magnetic configurations using the Stokes I, Q, U, and V maps of the IRIM. As a results, we found that it has a high blue-shift velocity (~2km) faster than the photospheric features and has a strong horizontal component of the magnetic field. Based on our findings, we suggest that it is associated with small flux emergence, which occurs very close to the pore. Even though it is very small structure, this kind of magnetic configuration can be in chare of the upper chromosphere heating, especially above the pore.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.40 no.11
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• pp.957-962
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• 2012

Fluid/structure interaction (FSI) analysis is necessary to predict the response of a system in which aerodynamic pressure causes deformation of the structure, and vice versa. In dealing with a nonlinear behavior of the structure, however, a simple iterative algorithm of aerodynamic analysis with structural analysis yields no accurate results since aerodynamic pressure need to be changed in accordance with the deformation of structures. In this study, we explore an efficient and accurate method for integrating FSI analysis into structural nonlinear systems. During the course of nonlinear structural analysis, loading conditions are periodically updated by aerodynamic analysis. The accuracy and efficiency of the method is demonstrated with a high-aspect-ratio flexible wing of Global Hawk.

• International Journal of Aeronautical and Space Sciences
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• v.7 no.2
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• pp.110-120
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• 2006

There have been developed many structural and fluid rotorcraft analysis models in rotorcraft community, and also lots of investigations have been conducted to combine these two models. These investigations turn out to be good at predicting the airloads precisely, but they have not taken the blade nonlinear deflection into account. For this reason, the present paper adopts a sophisticated structural model which can describe three-dimensional nonlinear deflection of the blade. And it is combined with two types of aerodynamic model. First one is generalized Greenberg type of finite-time aerodynamic model, which is originally established for a fixed wing, but later modified to be suitable for coupled flap-lag-torsional aeroelastic analysis of the rotor blade. Second aerodynamic model is based on the unsteady source-doublet panel method coupled with a free wake model. The advantages of the present method are capabilities to consider thickness of the blade and more precise wake effects. Transient responses of the airloads and structural deflections in time domain are mainly analyzed in this paper.

• Journal of computational fluids engineering
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• v.12 no.2
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• pp.37-45
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• 2007

The hybrid Cartesian/immersed boundary method is applied to simulate fluid-structure interaction of a two-dimensional orbiting flexible foil. The elastic deformation of the flexible foil is modelled based on the dynamic equation of a thin-plate. At each time step, the locations and velocities of the Lagrangian control points on the flexible foil are used to reconstruct the boundary conditions for the flow solver based on the hybrid staggered/non-staggered grid. To test the developed code, the flow fields around a flapping elliptical wing are calculated. The time history of the vertical force component and the evolution of the vorticity fields are compared with recent other computations and good agreement is achieved. For the orbiting flexible foil, the vorticity fields are compared with those of the case without the deformation. The combined effects of the angle of attack and the orbit on the deformation are investigated. The grid independency study is carried out for the computed time history of the deformation at the tip.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.7
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• pp.713-718
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• 2006

Supersonic jet fighter aircraft have several different weapon loading configuration to support air-to-air combat and air-to-ground delivery of weapon modes. Especially, asymmetric loading configurations could result in decreased handling qualities for the pilot maneuvering of the aircraft. The design of the T-50 lateral-directional roll axis control laws change from beta-betadot feedback structure to simple roll rate feedback structure and gains such as F-16 in order to improve roll-off phenomena during pitch maneuver in asymmetric loading configuration. Consequently, it is found that the improved control law decreases the roll-off phenomenon in lateral axes during pitch maneuver, but initial roll response is very fast and wing pitching moment is increased. In this paper, we propose the lateral control law blending between beta-betadot and simple roll rate feedback system in order to decreases the roll-off phenomenon in lateral axes during pitch maneuver without degrading of roll performance.

• International Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.43-46
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• 2015

Aeroelastic gust response analysis plays an important role in design of aircrafts. For gust response analysis, frequency domain aerodynamics method has been typically used with generalized aerodynamic influence coefficient matrices at various reduced frequencies. However, it cannot be applied to the aeroservoelastic analysis, such as gust alleviation control. Time-domain state space (SS) models must be built. It attacks little attention that gust response analysis relies on continuous gust time-domain input signal in terms of its PSD function. The aim the current study is to provide a reduced-order modeling (ROM) method based on CFD to model gust responses for continuous gust responses for continuou gust inputs in time domain. The paper analyzed the gust response of AGARD445.6 wing subjected to the Dryden gust with ROMs and compared the difference between the rigid structure and elastic one. The results demonstrate that structure elastic effect effect should be considered in the design of aircraft.

• Journal of the Korean Institute of Rural Architecture
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• v.14 no.2
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• pp.27-34
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• 2012

This study aims to examine and classify plane types of Hanok at Haengbok village, analyze changes, area distribution and space structures of space components and sort plane types and their characteristics. Plane types were divided into four; living room, kitchen, dining room, etc. These plane types were labelled as LK type, L+K type, L+DK type and LDK type. LK type and L+K type were mainly found at single-wing house and made of living room and kitchen centered space structure, but substantially they were designed to ensure guest room, room and living room. Therefore, hanok built at Haengbok village were designed to combine the functions of residential function and lodging. Plane type was preferred to be used for double functions of residence and lodging. On the other side, L+DK type and LDK type were mainly found in house with several wings and they were designed centering around living room for family space. In addition entrance was placed to simplify entry from the outside and each room and guest room were arranged to be accessed from living room. It means that the functions of house focused on residence rather than lodging and all rooms had the structure to be used as residential space in case of emergency.