• Ocean Systems Engineering
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• v.6 no.3
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• pp.245-264
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• 2016

The iterative boundary element method (IBEM) developed originally before for cavitating two-dimensional (2-D) and three-dimensional (3-D) hydrofoils moving under free surface is modified and applied to the case of 2-D (two-dimensional) airfoils and 3-D (three-dimensional) wings over water. The calculation of the steady-state flow characteristics of an inviscid, incompressible fluid past 2-D airfoils and 3-D wings above free water surface is of practical importance for air-assisted marine vehicles such as some racing boats including catamarans with hydrofoils and WIG (Wing-In-Ground) effect crafts. In the present paper, the effects of free surface both on 2-D airfoils and 3-D wings moving steadily over free water surface are investigated in detail. The iterative numerical method (IBEM) based on the Green's theorem allows separating the airfoil or wing problems and the free surface problem. Both the 2-D airfoil surface (or 3-D wing surface) and the free surface are modeled with constant strength dipole and constant strength source panels. While the kinematic boundary condition is applied on the airfoil surface or on the wing surface, the linearized kinematic-dynamic combined condition is applied on the free surface. The source strengths on the free surface are expressed in terms of perturbation potential by applying the linearized free surface conditions. No radiation condition is enforced for downstream boundary in 2-D airfoil and 3-D wing cases and transverse boundaries in only 3-D wing case. The method is first applied to 2-D NACA0004 airfoil with angle of attack of four degrees to validate the method. The effects of height of 2-D airfoil from free surface and Froude number on lift and drag coefficients are investigated. The method is also applied to NACA0015 airfoil for another validation with experiments in case of ground effect. The lift coefficient with different clearance values are compared with those of experiments. The numerical method is then applied to NACA0012 airfoil with the angle of attack of five degrees and the effects of Froude number and clearance on the lift and drag coefficients are discussed. The method is lastly applied to a rectangular 3-D wing and the effects of Froude number on wing performance have been investigated. The numerical results for wing moving under free surface have also been compared with those of the same wing moving above free surface. It has been found that the free surface can affect the wing performance significantly.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.983-989
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• 2007

The bird strike simulation is a problem characterized by a high degree of uncertainty. It deals with nonlinear dynamics, complicated models of bird materials and geometry, as well as a plenty of possible boundary and initial conditions. In this complex field, uncertainty management plays an important role. This paper aims to assess the effect of input uncertainty of bird strike analysis on the impact behavior of the leading edge of the WIG(Wing in Ground Effect) craft obtained with finite element analysis using LS-DYNA 3D. The uncertainties of the bird strike simulation arise due to imprecision or lack of information, due to variability or scatter, or as a consequence of model simplification. These uncertain parameters are represented by fuzzy numbers with their membership functions quantifying an initial guess for the actual value of the model parameter. Using the transformation method as a special implementation of fuzzy arithmetic, the model can be analyzed with the intention of determining the influence of each uncertain parameter on the overall bird strike behavior.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.2
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• pp.149-156
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• 2007

The present study provides structural design and analysis of main wing and horizontal tail of a small scale WIG(Wing in Ground Effect) vehicle which has been developed as a part of the high speed maritime transportation system for the future of Korea. Weight saving as well as structural stability could be achieved by skin-spar with foam sandwich design and with wide application of carbon/epoxy composite material. A commercial FEM code, NASTRAN, was utilized to confirm the structural safety and stability through sequential design modifications to meet the final design goal. In addition, each wing and the fuselage were fastened together by eight insert bolts with high strength to accomodate easy assembling and disassembling as well as to guarantee a service life longer than 20 years.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.2 s.152
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• pp.180-188
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• 2007

In this paper the longitudinal control problem for the large WIG(wing-in-ground effect) craft is considered in the sense of the control augmentation system(CAS) derived by control surface of elevator. In order to achieve longitudinally stable systems, two modes of CAS are applied to the control systems which are pitch rate hold mode and pitch hold mode for steady flight. Since the employed CASs include the dynamic properties of the actuator time delay and the low pass filter, it provides the possible solution to be applicable to real systems. Nonlinear model simulations are fulfilled to investigate the effectiveness of the applied CASs with wind disturbance.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.911-916
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• 2012

The purpose of this study is to review and suggest coastal shipping policies for introduction of WIG craft into domenstic passenger shipping market. Two Korean companies are leading in the development of WIG craft as an innovative sea transportation vehicle, and it is awaiting for commercialization. WIG craft is expected to be commercialized from coastal passenger market and we used AHP method to investigate the major factors and its' priority for smooth market entry. The results shows that priorities are on the WIG craft legislation, dock installation and operation, port state control, and pilot hiring and training, craft maintenance, and ship's certification in order.

• The Korean Journal of Air & Space Law and Policy
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• v.35 no.3
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• pp.95-126
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• 2020

In 2017, the world's first WIG ship (WIG: Wing In-Ground) pilot's license written test was conducted in Korea. The WIG ship is a ship that combines the characteristics of ships and airplanes. Therefore, the pilot of the WIG ship was allowed to apply only for those who had the aircraft pilot's license and the 6th class marine nautical license. The WIG ship pilot's license system was first introduced by Korea, so there are no international standards for the license system, and the introduction of a domestic qualification system also requires institutional arrangements due to various restrictions such as pilot training. However, in order to become a valuable industry as a future growth engine for the ocean, several urgent problems need to be solved, and that is the training of manpower for WIG ships. Therefore, I reviewed the institutional issues related to pilot training as this subject. Since 2001, various countries around the world have been discussing this issue, centering on IMO, and Korea has continued to participate and cooperate in IMO meetings. And the national qualification test for surface flying ships was conducted in Korea from 2011. However, there are still problems to be solved, and I pointed out the advancement of the manpower training system, the education and training system, and the designated national educational institution system. As a solution to this, it was suggested through the improvement of the license system and the operation of designated educational institutions. Among these solutions, I believe that the best way is to entrust the operation of designated national educational institutions to private educational institutions. However, I propose a plan that the government entrusts to private educational institutions, but the government is responsible for licensing and supervision. WIG ship will be a new market for the aviation industry and aviation workers.

• Bulletin of the Society of Naval Architects of Korea
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• v.32 no.5
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• pp.19-26
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• 1995

표면효과익선(WIG : Wing-In-Ground Effect Ship)은 해면 위를 낮게 비행함으로써 표면효과에 의한 양력 증가를 얻게 되어 초고속으로 운행할 수 있는 선박과 항공기의 중간형태의 차세대 해상운송 수단이다. 해면 위에 직접 이.착륙이 가능하기 때문에 별도의 활주로가 필요 없으며 수륙양용으로 사용 가능하다. 연근해 도서지방 관광 및 신선도 유지가 필수적인 신속화물의 수 송에도 사용될 수 있으며 해난사고 구난 및 해양 경비용으로도 사용가능한 해상 운송수단이다. 본 고에서는 표면효과익선의 특징을 간략히 살펴보고 21세기 고속해상운송수단으로 사용될 가 능성에 대한 경제성 검토 및 핵심애로기술을 살펴보았으며 러시아 표면효과익선의 발달과정과 개발된 선종의 특징을 조사하였다.

• Composites Research
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• v.23 no.1
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• pp.44-50
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• 2010

In this paper, two different experiments, namely, salt water spray and salt water immersion, were performed to reproduce the contact of composites with the seawater for three kinds of woven fabric composite material systems which would be used for the WIG(wing in ground effect)craft. After aging 140 days in the salt water environment, material properties of carbon/epoxy and glass/epoxy composite such as tensile, compressive and shear stiffness and strength, and inter-laminar shear strength (ILSS) were measured. By comparing baseline material properties with degraded ones, the effects of the salt water environment on the composite mechanical properties were evaluated. From the experiments, it was confirmed that the difference in aging conditions had very small influence on composite properties. And it was found that tensile strength of carbon/epoxy composites showed little degradation, but much more degradation was observed in glass/epoxy composites. And large degradations on matrix dominant properties were observed. The salt water could damage the fiber-matrix interface, matrix properties and the glass fiber.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.3
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• pp.57-68
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• 2000

The Power Augmented Ram(PAR) effect, which blows the down stream of the propellers into the underside of the wings and hence increases the pressure between the lower surface of the wings and the sea surface, is known significantly to enhance the performance of the WIG concept by reducing the take-off and landing speeds. The aerodynamic characteristics of a 20 passenger PARWIG are investigated by wind tunnel tests with the 1/20 scale model. The efflux of the forward mounted propellers are simulated by jet flows with a blower and duct system. The lift, drag, and pitch moment of the model with various ground clearances, angles of attack and flap angles are measured for the various jet velocities, jet nozzle angles, horizontal and vertical positions of the nozzle, and the nozzle diameters. The aerodynamic characteristics of the PARWIG due to these parametric changes are compared and pertinent discussions are included. It is shown that the proper use of the PAR can increase the lift coefficient of as much as up to 4.