• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.518-522
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• 2016

항공기 운항 중 사고가 가장 많이 발생하는 순간이 이착륙 순간이다. 사고의 원인은 실속(Stall)으로 인한 조종성 상실, 버드 스트라이크 등의 이유들이 있다. 본 연구에서는 항공기 날개에 구멍을 내서 구조적인 변화를 통해 이 착륙 시에 가장 많이 적용되는 받음각인 $10^{\circ}$에서 흐름의 박리가 지연되고, 양항비가 상승되는 효과를 기대하고 $10^{\circ}$이외의 받음각에서 박리가 지연되는지 해석을 진행하였다. 본 연구에서의 최종적 목표는 곡선형태의 구조변화 형상과 이를 실제 항공기에 적용이 가능하도록 제작성과 경제성을 고려하여 단순화 하는 작업을 진행하고 곡선 형태와 같은 효과를 얻고자 해석을 진행하였다. 받음각 $10^{\circ}$에서 해석을 진행한 경우 모든 형상들이 흐름의 박리를 지연시키는 효과를 가져왔다.

• Economic and Environmental Geology
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• v.49 no.4
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• pp.315-323
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• 2016

This study reports a gneiss dome in the Hongseong area, southwestern margin of the Gyeonggi massif. This gneiss dome, named here as 'Oseosan dome' because it is located around the Oseosan, the highest peak along the western coastal area, is composed mainly of the Neoproterozoic to Paleozoic ortho- and paragneiss, mafic metavolcanic rock, and metadolerite. Migmatization affected these rock units, in which leucocratic(granitic) materials derived from anatexis frequently occur as patch and vein parallel to or cutting through internal foliation. The Oseosan dome shows overall concentric geometry and outward-dipping internal foliation, but also partly complicatedly changeable or inward-dipping foliation. Taking available petrological and geochronological data into account, the Oseosan dome is interpreted to be exhumed quickly into the upper crustal level during the Late Triassic, accompanied in part with anatexis and granite intrusion. In addition, extensional shear zone intruded by the Late Triassic synkinematic granite and sedimentary basin have been reported around the Oseosan dome. These evidences possibly suggest that the Oseosan dome formed in closely associated with the Late Triassic extensional movement and diapiric flow. Alternatively, 1) thrust- or reverse fault-related doming or 2) interference between independent folds during structural inversion of the Late Traissic to Middle Jurassic sedimentary basin can be also considered as dome-forming process. However, considering the northern limb of the Oseosan dome, cutting by the Late Traissic granite, and the southern limb, cutting by contractional fault reactivated after the Middle Jurassic, it is likely that the domal structure formed during or prior to the Late Triassic.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.565-571
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• 2020

In this paper, precision and efficient nonlinear structural analysis for the aircraft wing-box model is developed. Herein, nonlinear shell element based on the co-rotational (CR) formulation is implemented. Then, parallel computing algorithm, the element-based partitioning technique is developed to accelerate the computational efficiency of the nonlinear structural analysis. Finally, computational performance, i.e., accuracy and efficiency, of the proposed analysis is evaluated by comparing with that of the existing commercial software.

• 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.

• The Journal of the Petrological Society of Korea
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• v.14 no.2 s.40
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• pp.108-115
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• 2005

Gyeonggi metamorphic complex in the Gwangju area include banded biotite gneiss and quartzofeldspathic gneiss. Detailed structural analysis suggests that structural elements in the study area were formed by at least five phase of deformations. Penetrative compositional foliations(S1) formed in the banded gneiss during the first metamorphism and deformation (D1). After intrusion of plutonic rocks, the second deformation (D2) produced S2 foliations in the banded gneiss and quartzofeldspathic gneiss during the second metamorphism. D3 structures are represented by isoclinal folds (F3) whose axial surfaces are parallel to S3 foliations. The N-S oriented shortening (D4) was accommodated by closed upright F4 fold with about 100m of axial surface separation. F4 fold is refolded by regional F5 folding resulting in different orientation and fold style of F4 fold according to the position of F5 fold. The F4 fold with tight interlimb angle is subparallel to the axial surface (north-south) of F5 fold in the core of the F5 fold. In contrast the F4 fold trends northeast in the western limb and northwest in the eastern limb of F5 fold. The interlimb angle is larger in the limbs than that in the core of F5 fold. The trace of foliations is constrained by mainly F4 and F5 folds. Joint fanning around fold is developed in the limbs of F5 fold and bc joints are dominant in the hinge area of F5 fold. A strike-slip fault had developed in tile central part of the study area after F5 folding. The orientation of joint and foliation is rotated anticlockwise about $15^{\circ}$ by the landslide occurred during the Quaternary.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.532-540
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• 2008

Recently there are growing interests in calculating aerodynamic characteristics of aircraft configurations with structural deformation using the FSI(Fluid-Structure Interaction) system in which CFD(Computational Fluid Dynamics) and CSD(Computational Structure Dynamics) modules are coupled. In this paper the FSI system comprised of CAD, CFD, CSD, VSI(Volume Spline Interpolation) and grid deformation modules was constructed in order to investigate aerodynamic characteristics of the deformed shape. In the process VSI and grid generation modules are developed to combine CSD and CFD routines and to regenerate the aerodynamic grids for the deformed shape, respectively. For the CFD and CSD analysis, commercial programs FLUENT and NASTRAN were used. As a test model, DLR-F4 wing configuration was chosen and its aerodynamic characteristics were calculated by applying the static FSI system. It was shown that lift and drag coefficients of the wing at mach number 0.75 are reduced to 20.26% and 18.5%, respectively, owing to the structural deformation.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.10
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• pp.1116-1120
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• 2010

Low cost patch array antenna for high sensitivity electromagnetic(EM) sensor is presented. The operating frequency band of the antenna is 24.05~24.25 GHz. Array structure is the symmetrical pattern by Chebyshev polynomial and the feed point is located in the middle of the array. Also, the gain of the array antenna can be increased by the side wings which are connected with the ground plane. It is proved through simulation and the measurement results that the operating frequency and the side-lobe level(SLL) are rarely changed when the inclined angle of the side wings is varied.

• The KSFM Journal of Fluid Machinery
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• v.15 no.1
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• pp.46-51
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• 2012

This study is to confirm the deformation of blade when the location of stacking is moving. Also, it desire to determine the most stable location of stacking from the analysis. In the previous study, it is Known that moving the location of stacking is not influence to the aerodynamic performance. In this study SolidWorks premium 2010 SP4 is used for structure analysis. In reference blade and other 3 model analysis, the two mesh type is used, one is standard mesh type in SolidWorks, the other is curvature-based mesh type. The result of curvature-based mesh type is more stable than one of the standard mesh type regardless of mesh size, the number of mesh. The deformation of blade tip is the smallest, when the location of stacking is identical to the center of gravity of the blade section profile. So, if possible is design, this study recommends that the location of stacking is identical to the center of gravity the blade.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.321-326
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• 2007

The joined-wing is a new concept of the airplane wing. The fore-wing and the aft-wing arc joined together in the joined-wing. The range and loiter are longer than those of a conventional wing. The joined-wing can lead to increased aerodynamic performances and reduction of the structural weight. The structural behavior of the joined-wing has a high geometric nonlinearity according to the external loads. The gust loads are the most critical loading conditions in the structural design of the joined-wing. The nonlinear behavior should be considered in the optimization of the joined-wing. It is well known that conventional nonlinear response optimization is extremely expensive: therefore, the conventional method is almost impossible to use in large scale structures such as the joined-wing. In this research, geometric nonlinear response structural optimization is carried out using equivalent loads. Equivalent loads are the load sets which generate the same response field in linear analysis as that from nonlinear analysis. In the equivalent loads method, the external loads are transformed to the equivalent loads (EL) for linear static analysis, and linear response optimization is carried out based on the EL.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.2
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• pp.131-138
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• 2009

Analytical modal verification is considered as the process to provide an acceptable description of the subject structure's behaviour. In general, results of original analytical model are different with actual structure results to uncertainty like non-linearity of material, boundary and modified shape, etc. In this paper, the dynamic model of glider's wing is correlated with static deformation and vibration test results by goal-attainment method, multi-objects optimization technique. The structural responses are predicted by using finite element method and optimization is carried out by using the SQP(sequential quadratic programming) method which is widely used in the constrained nonlinear optimization problem. The MAC(Modal Assurance Criterion) is used to modify the mode shapes and quantify the similarity.