• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.217-221
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• 2007

In this study, forced vibrations analysis was performed for main wing of small scale WIG vehicle which is equipped two-stroke pusher type propeller engine, in terms of structural. for the frequency response analysis, excitations were assumed by H-mode(Horizontal mode), X-mode(Twisted mode) which is main vibration mode of engine, and for the transient response analysis, excitations were assumed by L-mode(Longitudinal mode) with propeller thrust which is occurred when it revolution.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.8-13
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• 2008

The fuel tank systems of fixed wing and rotary wing aircrafts require the self-sealing and crash-worthiness for their survivability. For these requirements, the flexible composite fuel tank is generally used. In this study, the drop and penetration performance of a fuel tank is investigated. The FE simulation includes the drop and penetration test of a fuel tank using MSC.DYTRAN. MSC.DYTRAN can provide the fluid-structure modeling of these test from Euler and Lagrange grids. Using MSC.DYTRAN, the finite modeling of the test cube of the flexible fuel tank and its FE simulation are performed for various environments. The simulation results can show if the test cube satisfies the performance requirements of the fuel tank.

• Korean journal of applied entomology
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• v.56 no.4
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• pp.435-436
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• 2017

Subgena and clypeus are a continuous plate, so should be collectively called as peristoma. Subsequently, subgenal sulcus is revised into peristomal sulcus or cranio-stomal sulcus. Ptilinal suture on dipteran adult head is revised into ptilinal fissure. Notal and pleural wing processes are revised into notal and pleural process, respectively. The lower plate of abdomen is ventum, while that of thorax is sternum.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.23 no.1
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• pp.96-102
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• 2015

Composite materials are widely used as structural materials for manufacturing an aircraft, due to their : low weight, low thermal expansion coefficient, production efficiency, anisotropy, corrosion resistance and long fatigue life. The range of using composite materials has been extended from the fuselage and the wings to the entire aircraft structure. In this paper, by analyzing the problems which were generated while designing and fabricating aircraft structures using composite materials, the differences between metallic structures and composite structures are described. In addition, the methodological improvement directions on design and fabricating are described.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.8
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• pp.975-983
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• 2011

A microfin on a heated surface and its effects of the heat transfer has been investigated. The thickness of the fin is about 8 micrometer to allow the flexible up-down motion of the fin. Two-way complete FSI (Fluid-Structure Interaction) method has been applied for the analysis. Firstly, the deformation of a microfin due to the pulsating flow is evaluated using structure analysis. The flow and temperature patterns are predicted by CFD (Computational Fluid Dynamics) method. At each time step, using the pressure force and temperature distribution from CFD, the deformation of the wing is evaluated by FEM. Also in order to estimate the resonance probability, the natural frequency of the wing structure is calculated by modal analysis. The proposed numerical procedure was validated through experiment using a single fin. Through this work, we show that the increase of 40% in heat transfer capacity using the microfin has been compared with that of flat plate case.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.9
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• pp.46-51
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• 2013

In this paper, the optimum placement and shape of UHF antenna on the unmanned aerial vehicle (UAV) are analyzed by using the electromagnetic (EM) simulation on the various locations. The FEKO was used for the EM-simulation. In order to reduce the complexity of simulation and minimize the runtime and memory usage, the composite aircraft structure is simplified as the PEC model excluding the radome structure. The simulation was performed on the wing and ventral fin of UAV, and the antenna shape used the monopole, dipole, and bent monopole antennas. When the monopole antenna is mounted under the wing, two antennas need to be mounted under the right and left wings, and those antennas have to be switched as the direction of UAV wing to the line of sight (LOS) data-link (DL) ground antenna. In the case of mounting under the ventral fin, one antenna can be used regardless of the direction of UAV wing to the LOS DL ground antenna. Also, the antenna gain is improved by the blockage reduction. The antenna gain is further improved by using the bent monopole antenna. The optimum solution of UHF antenna placement and shape on UAV is to mount the bent monopole antenna under the ventral fin.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.4 no.3_4
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• pp.79-91
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• 1971

A boat seine has been used as a major fishing gear for catching anchovy (Engraulis japonica) in the southern coastal waters of Korea since 1920s. The original seine was operated by two rowing boats as the haul seine. The rowing boats were, in recent, replaced by powered boats. The net size was enlarged by more than three times the original nit as they began to by operated in the deeper waters of approximately sixty meters. However, there are many problems in the efficiency of the fishing gear to be improved. The authors studied on the hydrodynamic resistance and performance of the boat seine net of the 1/10 scale model in tow. The results are summaried as follows. 1. The hydrodynamic resistance converted from model experiment into the full scale is: $$R_1=30,000\;v^{1.2}\;(0.2{\leqq}v{\leqq}1.0)$$ $$R_2=16,000\;v^2\;(0.2{\leqq}v{\leqq}0.6)$$ where $R_1$ and $R_2$ denote the resistance of whole gear and of bag net in kg respectively, and v the speed of flow in m/sec. 2. In the extension wing, approximately seventy percent of the length of the ground rope from the towing end to the inside-wing slopes down from sea level toward the sea bottom, while the thirty percent of the inside of it remains parallel with th: 5:a level. The performance is regarded to b: inefficient for driving fish shoal into the inside-wing, especially for the shoal diving suddenly. 3. At the towing speed higher than 0.2 m/sec, the trailing edge of the inside-wing is blown backward beyond the seaming line connecting the inside-wing and the mouth of the bag net. It is regarded as an unreasonable performance to drive the fish shoal smoothly into the bag net. 4. At the towing speed higher than 0.2 m/sec, the posterior end of the lower bosom is lifted up above the level of the ground rope of the inside-wing. It is considered that the fish shoal diving suddenly can escape through the discrepancy between the lower bosom and the sea bottom, even if the ground rope of the inside-wing sweeps the sea bottom. 5. The angle of inclination of the upper bosom is estimated as $35\~40^{\circ}$. It seems that the inclination is too steep to drive smoothly the fish shoal diving toward the sea bottom into the bag net. 6. In structure, circumference of the posterior section of the bag net is wider by 1.3 times that of the anterior section. Actually in towing at a speed higher than 0.2m/sec, however, the circumference of the posterior section becomes smaller than that of the anterior section. It is recommended to be designed in a long cylindrical form.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.716-726
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• 2010

In this research, design optimization of an aircraft wing has been performed using the fully automated Multidisciplinary Design Optimization (MDO) framework, which integrates aerodynamic and structural analysis considering nonlinear structural behavior. A computational fluid dynamics (CFD) mesh is generated automatically from parametric modeling using CATIA and Gambit, followed by an automatic flow analysis using FLUENT. A computational structure mechanics (CSM) mesh is generated automatically by the parametric method of the CATIA and visual basic script of NASTRAN-FX. The structure is analyzed by ABAQUS. Interaction between CFD and CSM is performed by a fully automated system. The Response Surface Method (RSM) is applied for optimization, helping to achieve the global optimum. The optimization design result demonstrates successful application of the fully automated MDO framework.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.1
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• pp.33-39
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• 2015

This paper describes test result of the Supersonic Wing Structure and the utility of thermal test equipment, which is possible to heat rapidly and continuously above $1,000^{\circ}C$, the durability and reliability of which are improved compared with the existing equipment. Through the test, we could predict the amount of strength reduction of the wing due to aerodynamic heating, caused by exposure of high temperature. Recently the aerodynamic heating temperature of the supersonic flying object is rapidly increased. It is possible to carry out the High Temperature Strength Test on the hypersonic speed flying object with the newly designed thermal test equipment. Because of that, we can upgrade the High Temperature Strength Structure Test technique and test reliability.

• Composites Research
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• v.32 no.1
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• pp.45-49
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• 2019

Fiber reinforced composites fabricated by the resin film infusion (RFI) process, which is one of the outof-autoclave process, have the advantage of significantly reducing the processing cost in large structures while having excellent mechanical properties and uniform impregnation of the resin. In this study, we applied RFI carbon fiber composites to unmanned aerial vehicle structures to improve structural safety and achieve weight reduction. The tensile test results showed that the strength was 46% higher than that of generic T300 grade plain weave carbon fiber composites. As a result of the layup design and finite element analysis of the composite wing structure using the above material properties, the wing tip deflection is decreased by 31%, the structural safety factor is increased by 28% and the weight of the entire structure can be reduced by more than 10% compared to the reference model using glass fiber composite material.