• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.1
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• pp.29-41
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• 2021

The PID controller with fin angle and thrust as control input was designed based on the aerodynamic data of scramjet system. Flight simulation following a given trajectory which strike the target point after climb and cruise with constant dynamic pressure was conducted. After that, the required thrust for the climb and cruise was calculated and the required fuel flow rate for the hydrogen fuel dual mode scramjet combustor was analyzed. The combustor analysis of this study which conducted on integrated model of independently developed inlet, combustor, nozzles and external aerodynamic models, laying the foundation for the integrated design of the air breathing hypersonic system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.655-663
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• 2010

DUP (direct underside pressurization) is a device that can considerably increase lift, reduce take-off speed and minimize hump drag when a WIG effect vehicle takes off on the water surface. A 3-dimensional numerical investigation of a WIG effect vehicle with DUP is performed to analyze aerodynamic characteristics and the static height stability. The model vehicle, named Aircat, consists of a propeller in the middle of a fuselage, an air chamber under the fuselage, Lippisch-type wings and a large horizontal T-tail. The lift is mainly increased by the stagnation of the accelerated air coming into the air chamber through the channel in the middle of the fuselage. However, the accelerated air increases drag as well as reduces static height stability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.575-580
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• 2007

During the conceptual design phase of a canard type high maneuverable aircraft, the low speed small scale wind tunnel test was conducted to investigate the high angle-of-attack static stability of the aircraft. In this study, 1/50th scale generic canard-body-wing model was used for the small scale wind tunnel test. For the analysis of static stability including high angle-of-attack nonlinear characteristics, the vertical tail effects were studied due to canard deflections. In addition, the nose chine effects were studied at high angle-of-attack. Based on the results obtained from the experimental study, the configuration change effects for canard type aircraft on high angle-of-attack static stability have been able to analyze.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.10
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• pp.809-819
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• 2020

In this study, the twist angle and wing planform shapes were selected as design variables and optimized to secure the stability of the flying-wing type UAV. Flying-wing aircraft has no separated fuselage and tails, which has advantages in aerodynamic characteristics and stealth performance, but it is difficult to secure the flight stability. In this paper, the sweep back angle and twist angle were optimized to obtain the lateral stability, the static margin and wing planform shapes were optimized to improve the longitudinal stability of the flying-wing, then effect of the twist angle was confirmed by comparing the stability of the shape with the winglet and the shape with the twist angle. In the optimization formulation, focusing on improving stability, constraints were established, objective functions and design variables were set, then design variable sensitivity analysis was performed using the Sobol method. AVL was used for aerodynamic analysis and stability analysis, and SQP was used for optimization. The CFD analysis of the optimized shape and the simulation of the dynamic stability proved that the twist angle can be applied to the improvement of the lateral stability as well as the stealth performance in the flying-wing instead of the winglet.

• Ocean and Polar Research
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• v.26 no.3
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• pp.425-431
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• 2004

The study focuses on the morphology of larval and juvenile codlets, Bregmaceros atlanticus, collected from the East China Sea in May 2001 and September 2002. A total of 47 individuals were collected by using an IKMT, and the range of their body lengths was $2.41{\sim}17.18$ mm. Specimens can be categorized into two groups: larvae and juvenile. The first group, in which the yolk is completely absorbed, had a body length of 2.41m. They had big heads, and large and thick melanophores were sparsely scattered about the head, bottom of the pectoral fins, rear parts of the trunk and ends of the notochords. The specimens had a body length of 2.54mm and over, and thin and elongated body trunks. Their heads were significantly smaller, including the body depth, and melanophores were coarsely developed all over their bodies. Occipital rays, the first and unique-ray dorsal fin, were observed on individuals of body length greater than 4.01 m, and the rays grew proportionally with body length, but didn't reach the root of the second dorsal fin. The second group, juveniles, had an body length of 9.82mm and over, and their fin rays satisfied the completed numbers of rays and vertebrae for adults. Melanophores were densely scattered all over the body, where thick colors were observed on the rear parts of the dorsal and anal fins and front part of the caudal fin.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 1999.10a
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• pp.419-424
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• 1999

In this paper, the comparison of the first order approximation schemes such as SLP (sequential linear programming), CONLIN(convex linearization), MMA(method of moving asymptotes) and the second order approximation scheme, SQP(sequential quadratic programming) was accomplished for optimization of and nonlinear structures. It was found that MMA and SQP(sequential quadratic programming) was accomplished for optimization of and nonlinear structures. It was found that MMA and SQP are the most efficient methods for optimization. But the number of function call of SQP is much more than that of MMA. Therefore, when it is considered with the expense of computation, MMA is more efficient than SQP. In order to examine the efficiency of MMA for complex optimization problem, it was applied to the helicopter tail boom considering column buckling and local wall buckling constraints. It is concluded that MMA can be a very efficient approximation scheme from simple problems to complex problems.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.35-45
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• 2005

TR-E2 configuration designed by Bell Textron was tested in KARI 1-m wind tunnel. To explore aerodynamic characteristics for the given configuration, a $12\%$ scaled model was fabricated and tested. Wind tunnel test for TR-E2 had been performed by changing the incidence angles of wing and deflection angles of control surfaces. Test result showed that the lower wing incidence angle has more favorable lift to drag ratio compared with original design. Longitudinal and directional characteristics of TR-E2 were found to be stable for the pitch and yaw motions. However, the lateral stability of TR-E2 is not stable for certain control surface deflection.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.3 s.234
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• pp.295-305
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• 2005

To improve the aerodynamic effciency of TR-E2, a new configuration so called TR-E2Sl was introduced. TR-2251 is composed of different wing airfoil section and T-tail shape compared with TR-E2. Wind tunnel test for TR-EBS1 had been performed by changing the incidence angles of wing and deflection angles of control surfaces such as elevator and rudder. Also the on/off effect of ventral fin attached underneath of AFT fuselage was tested. Test result showed that variations of wing incidence angle did not cause any severe differences in aerodynamic characteristics. Longitudinal and directional characteristics of TR-E2S1 show stable for the pitch and yaw motions. However, the lateral stability of TR-E2S1 is not stable for a certain control surface deflection.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.7
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• pp.547-555
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• 2003

This paper presents an adaptive control against uncertainties in tail-controlled STT (Skid-to-Turn) missiles. We derive an analytic uncertainty model from a parametric affine missile model developed by the authors. Based on this analytic model, an adaptive feedback linearizing control law accompanied by a sliding mode control law is proposed. We provide analyses of stability and output tracking performance of the overall adaptive missile system. The performance and validity of the proposed adaptive control scheme are demonstrated by simulation.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.343-348
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• 2013

초임계 익형은 천음속 영역에서 비행하는 상업용 민간 항공기와 전투기 날개의 공력성능을 향상시키기 위해 Whitcomb R. T.가 제안 하였다. 초임계 익형은 상부표면을 평평하게 디자인하여 임계마하수보다 큰 마하수에서 나타나는 익형 주위의 충격파 출현을 지연시킴으로써 항력을 줄일 수 있고, 상부 표면의 평면 설계로 인한 양력 감소를 보정하기 위하여 하부 표면의 꼬리부분에 캠버가 있는 형상을 하고 있다. 본 연구에서는 EDISON CFD를 이용하여, 초임계 익형의 공력특성을 해석하고 Xfoil의 data와 비교 분석하였다. 또한, 초임계 익형의 형상을 변경하여 두께와 뒷전 캠버가 다른 초임계 익형을 설계하였다. 새로운 초임계 익형의 형상은 상용 프로그램 Maple12을 이용하여 Whitcomb Integral Supercritical Airfoil의 형상을 수정하여 구할 수 있다. 초임계 익형 주위의 유동을 2D압축성 유동으로 가정하고 EDISON CFD의 2D_Comp-2.0 솔버를 사용하여 수치해석을 수행하였다.