• 한국동물위생학회지
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• 제31권1호
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• pp.161-166
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• 2008

Deep pectoral myopathy (DPM), also known as Oregon muscle disease or green muscle disease, was first described in 1968 by Dickinson et al as "degenerative myopathy" in turkeys. Even though this condition was first recognized in adult meat-type turkey and chicken breeders, it is becoming more and more common in meat-type growing birds. DPM occurs exclusively in birds that have been specially selected for breast muscle development. It is generally recognized that DPM is an ischemic necrosis that develops in the deep pectoral muscle (supracoracoideus or pectoralis minor muscle) mainly because this muscle is surrounded by inelastic fascia and the sternum, which do not allow the muscle mass to swell in response to the physiological changes occurring when muscle are exercised, as in wing flapping. The lesion does not impair the general health of birds and is generally found during cut-up and deboning, moreover, it can be both unilateral or bilateral, affecting just one or both pectoralis minor muscle, respectively. No public health significance is associated to DPM, but it is aesthetically undesirable. The fillet should be removed, whereas the rest of the carcass is still fit for human consumption. However, the required trimming operations determine the downgrading of the products and produce an economic loss for the industry, especially because it affects the more valuable part of the carcass. The incidence of DPM increases with market weight in broilers, with more cases reported in higher-yielding strains and in males. Increased bird activity (flock nervousness, flightiness, struggle, and wing flapping) induced by factors such as feed or water outages, lighting programs and intensity, human activity, and excessive noises in and around chicken houses should be looked at as a trigger for the development of DPM in broiler. However, most of the studies conducted to evaluate the incidence of DPM in poultry are concerned with parental commercial breeding stocks under experimental conditions (Bianchi et al. 2006. Poult Sci 85 : 1843-1846). There is a possible genetic relationship between the selection for large-breasted birds and this condition. Management procedures that discourage excessive wing flapping would reduce the incidence (Jordan and Pattison. 1998. Poultry diseases. 398-399).

• 한국항공운항학회지
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• 제14권1호
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• pp.22-27
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• 2006

The linear and nonlinear aeroelastic analyses of a flat plate wing with flaperon have been performed by using frequency-domain and time-domain analyses. Natural modes from free vibration analysis and a doublet-hybrid method (DHM) are used for the computation of subsonic unsteady aerodynamic forces. The flaperon hinge is represented by a free-play spring and is linearized by the described function method. The linear and nonlinear flutter analyses indicate that flapping mode of the flaperon, the hinge stiffness and free-play of hinge have significant effects on the aeroelastic characteristics. From the nonlinear flutter analysis, different modes like stable and unstable limit-cycle-oscillation are observed in same flutter velocity depending on initial conditions.

• 한국항공우주학회지
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• 제34권11호
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• pp.18-25
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• 2006

비정상 공기력 측정이 두 쌍의 날개를 갖는 잠자리 유형 모델의 위상차에 따른 효과를 조사하기 위하여 수행되었다. 잠자리 유형 모델의 플런징 운동에 의하여 발생된 공기역학적인 힘을 측정하기 위하여 로드셀을 사용하였다. 본 잠자리 유형 모델은 실제 잠자리와 동역학적으로 상사하며, 앞뒤날개는 각각 0°의 10°의 붙임각(incidence angle)을 가지고 있다. 다른 실험 조건은 다음과 같다. 자유류의 속도는 1.6 m/sec이고, 이와 관련된 시위 레이놀즈수 2.88×103이며, 앞뒤날개의 위상차는 각각 0°, 90°, 180°, 그리고 270°이다. 잠자리 유형 날개의 한 주기 동안 공기역학적 계수의 변화가 제시되었다. 연구 결과는 잠자리 유형 모델의 양력은 앞뒤날개가 downstroke 운동을 수행할 때 발생되며, 뒷날개가 downstroke 운동과정을 수행하면 양력 발생과 함께 항력도 발생한다는 것을 보여준다.

• 한국항공우주학회지
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• 제31권6호
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• pp.1-7
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• 2003

본 연구에서는 3차원 대칭형 날개의 정상/비정상상대에서의 공기력 특성을 Vortex 패널법을 이용하여 수치적으로 연구했다. 이 프로그램은 날개 표면에 분포된 x, y 방향에 따라 선형적으로 변화는 와(Vortex)를 이용하는 프로그램을 기반으로 하여 3차원 날개 주위의 비압축성 포텐셜 흐름에 적용하였고 박리와 후류의 변형은 고려하지 않았다. NACA Airfoil 자료와 비교한 계산결과는 매우 만족스러운 일치를 보여주었다. 또한 갑작스러운 pitch-up운동과 일정한 각속도로 피칭운동을 하는 비정상 날개에 대해서도 본 방법을 적용하였다. 비정상 상태의 연구에서는 출발와류의 생성과 시간에 따른 위치를 고려함으로서 출발와류가 날개의 공기력 특성에 미치는 영향을 계산하였다. 본 방법은 피칭이나 플래핑, 회전익 해석등의 더 복잡한 경우에도 적용되어질 수 있다.

• 한국전산유체공학회지
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• 제12권2호
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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.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.142-143
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• 2008

In the present work, high-speed video images of the ground take-off flight of a live butterfly were captured and their dynamic motions during the first full-stroke were analyzed. To capture the dynamic images of the take-off motion, the experimental setup consisted of a high-speed camera, a Xenon lamp as a light source and a transparent chamber of $15^W{\times}15^L{\times}17^H$ $cm^3$ in physical size. The ambient temperature and supplementary lighting devices were precisely controlled. The weight and wing span of the butterfly tested in this study was 104 mg and 63.14 mm, respectively. The ground take-off images were captured with 4000 fps with a spatial resolution of (1024${\times}$512) pixels. The period of the first full-stroke was 80.5ms and the flapping speed of downstroke was 2 times faster than that of upstroke. As a result, butterflies used the fling and near-clap motion to generate lifting force and an interesting take-off behavior of early pronation and downstroke was observed.

• Journal of Mechanical Science and Technology
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• 제18권4호
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• pp.560-572
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• 2004

Aeroelastic response and control of airfoil-flap system exposed to sonic-boom, blast and gust loads in an incompressible subsonic flowfield are addressed. Analytical analysis and pertinent numerical simulations of the aeroelastic response of 3-DOF airfoil featuring plunging-pitching-flapping coupled motion subjected to gust and explosive pressures in terms of important characteristic parameters specifying configuration envelope are presented. The comparisons of uncontrolled aeroelastic response with controlled one of the wing obtained by feedback control methodology are supplied, which is implemented through the flap torque to suppress the flutter instability and enhance the subcritical aeroelastic response to time-dependent excitations.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.126-129
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• 2006

Many researchers have made an effort to explain flight mechanism of flapping insects. As a result, several unsteady mechanisms about lift generation in insect flight have been proposed. But it has a limits to elucidate insect's forward flight and abrupt thrust, because most of these are about insect's hovering flight. For this reason, the objective of this paper is to simulate "Figure-of-eight motion" of insect's wing during tethered flight for comprehending aerodynamic property in insect's forward flight.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.424-424
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• 2000

The implementation of a insect-based flying microrobot has been previously proposed as using magnetic force. The flying principle of a butterfly is different from that of a airplane, which obtain lifting force above the wings by a air stream with low pressure. Butterflies obtain lifting force below the wings by flapping. They can fly when drag during the down stroke is greater that during the up stroke. The structure of flying microrobot must satisfy these condition. And that must be manufacture lightly and keep balance for rising to the air sufficiently. Moreover the efficiency of an electromagnet is high and the flux density is sustained uniformly and widely Nevertheless these condition is satisfied, the implementation of a flying microrobot is very difficult as the flying microrobot has to fly without guides or sensor. We propose differently a new model il] comparison with that other paper has suggested. This imitates the form of the Korean shield-shaped kite.

• 한국항공우주학회지
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• 제38권7호
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• pp.647-654
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• 2010

본 연구에서는 날갯짓 비행체 날개의 유체-구조 연계를 고려한 설계나 날갯짓 비행체의 비행 동역학 및 제어 시뮬레이션에 적용 가능한 효율적인 공력모델을 제안하고, 풍동 실험을 통해 공력모델의 특성을 검증하고자 한다. 날갯짓 비행체는 저 레이놀즈 수 영역의 비정상 유동장의 지배를 받기 때문에, 이 영역에서 날개 운동에 따른 공력을 효과적으로 측정할 수 있도록 풍동실험장치를 설계 및 개발하였다. 본 연구의 실험장치 특성상 힘을 측정하는 2축-로드셀은 비관성계에 있기 때문에, 순수한 날개의 공력을 측정하기 위해서는 관성력을 보정해주어야 하며, 이에 대한 방법론을 수립하였다. 최종적으로 유동속도, 날개의 운동 주파수 및 고정 받음각에 따라 날개에 작용하는 양력 및 항력의 평균값 및 평균 제곱근 값을 비교함으로서 실험결과와 공력모델의 특성을 비교 검증하였다.