• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.415-420
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• 2007

Creatures in nature flap their wings to generate fluid dynamic forces that are required for the locomotion. Small-size creatures do not use flapping wings. Thus, it is questionable at which Reynolds number the propulsion using the flapping wings are effective. In this paper, the onset conditions of the thrust generation from the combined motion of flat plates (heaving, pitching in the motion and also tandem, biplane in the array) is investigated using a Lattice Boltzmann method. To solve the pitching motion of the plate on the regularly spaced lattices, 2-D moving boundary condition was implemented. The present method is validated by comparing the wake patterns behind a oscillating circular cylinder and its hydrodynamic characteristics with the CFD results. Present method can be applied to the design of micro flapping propulsors for biomedical use.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 추계학술대회
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• pp.133-136
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• 2009

본 논문에서는 야구 동영상에서 실시간으로 중요 이벤트 장면을 검출하는 알고리즘을 제안한다. 제안하는 알고리즘은 영상정보를 분석하여 Pitching 신과 Close Up 신을 추출하여 Play 구간을 검출하고, 오디오 정보를 분석하여 오디오 이벤트 구간을 검출한다. Play 구간의시작인 Pitching 신을 검출하기 위해서는 오프라인 모델과 온라인 모델을 혼용하여 다양한 환경에 상관없이 높은 성능을 보일 수 있도록 하였으며, 아나운서의 억양 및 관중의 함성의 고조도가 높아지는 구간을 기반으로 검출된 오디오 이벤트 구간을 영상 정보 분석을 통해 획득된 Play 장면구간을 결합하여 중요 이벤트 장면 검출의 정확도를 높일 수 있도록 하였다. 실험에 의하면 제안하는 알고리즘은 1초의 동영상 데이터를 처리하는데 0.024초의 소요 시간이 필요하고, 0.89의 Recall과 0.975의 Precision 검출 성능을 보임을 알 수 있었다.

• 수산해양기술연구
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• 제41권1호
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• pp.64-69
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• 2005

In spite of many efforts, in the design of high speed fishing vessel the sea-keeping performance improvement without neglection of resistance-propulsion performance by hull form itself has its limitations. In this paper, the development of sea-keeping improving appendage pitching and trim improver for high speed planing hull on behalf of the hull form of fishing vessel has been introduced. The developed appendage verified its effectiveness in the full scale test and also has been proved the better resistance performance in the model test and full scale test.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2009년도 춘계학술발표회
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• pp.85-86
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• 2009

슬로싱 현상은 탱크안의 자유표면을 갖는 유체의 비선형거동으로 탱크안의 구조물에 동적 하중을 발생시키므로 일반적으로 해양 구조물의 설계에 중요한 문제이다. 이 연구에서는 피칭운동을 하는 사각탱크 내에서 자유표면을 갖는 유체의 슬로싱에 대해 실험적으로 연구하였다.

• 한국군사과학기술학회지
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• 제15권1호
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• pp.101-110
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• 2012

The side jet effects between jet flow and free-stream on a missile body were investigated by experimentally and numerically for modeling aerodynamic coefficients in pitch plane. K-factors for normal force and pitching moment were introduced to estimate the side jet effects. The main parameters of the jet interaction phenomena were angle of attack, jet pressure ratio, Mach number and jet bank angle. The K-factors for normal force coefficient and pitching moment coefficients in pitch plane were analysed.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.721-728
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• 2000

The shear behavior of sawtoothed artificial joints grouted with cement milk was investigated in the laboratory under constant normal stress conditions. Tests were conducted on joints with asperities having inclinations of 16.7$^{\circ}$ and 26.6$^{\circ}$, compresive strengths having 15MPa and 47MPa under a given range of normal stresses varying from 0.76 to 1.91 MPa and at a free condition of pitching, rolling and dilatancy. Results show that the effect of asperities on shear strength increase is significant up to asperity height to grout thickness (t/a) ratio of 0.3∼1.0. Increase of cohesion is the main cause of shear strength increase in cement grouted sawtoothed artificial joints.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.166.3-166
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• 2001

This paper presents a modeling and control method of active suspension system with full-car model by using H$\infty$ control theory. The full-car model has seven degree of freedom including heaving, pitching and rolling motions. As the control method, H$\infty$ controller is designed so as to guarantee the robustness of closed loop system under the presence of uncertainties and disturbances. Active system with H$\infty$ controller can reduce the accelerations of the car-body in the heaving, pitching and rolling directions. The effectiveness of the controller is proved through simulation results in both time and frequency domains.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2003년도 The Fifth Asian Computational Fluid Dynamics Conference
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• pp.291-293
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• 2003

This paper deals with a thrust generation of flapping-airfoil by dynamic stall. From many other previous research results, phase angle $ between pitching and plunging mode of flapping motion must be 90 deg. to satisfy maximum propulsive efficiency. In this case, leading edge vortex is relatively small. This phenomenon is related dynamic stall. So preventing leading edge vortex induced by dynamic stall guarantees maximum propulsive efficiency. But, in this paper we insist the leading edge vortex yields quite a positive influence on thrust generation and propulsive efficiency. In order to certify our opinion, pitching and plunging motions were calculated with the parameter of amplitude and frequency by using the unsteady, incompressible Navier-Stokes flow solver with a two-equation turbulence model. For more efficient computation, it is parallelized by MPI programming method.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.162-165
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• 1995

For an accurate on-line measurement of the ship's attitude the paper develops an intelligent sensing system which uses one servo-type accelerometer and two servo-type inclinometers appropriately located on the ship. By considering the dynamics of the servo-controlled rigid pendulums of the inclinometers, linear equations for the rolling and pitching of the ship are derived separately from each other. Moreover, one accelerometer is used for extracting the heaving signal. Through the introduction of linear dynamic models and the linear observation equations for the heaving, rolling and pitching, the on-line measurement of the three signals can be reduced to the state estimation of the linear dynamic systems. A bank of Kalman filters is adaptively used to achieve the on-line accurate state estimation and to overcome changes in parameters in the linear dynamic models.

• 한국가시화정보학회지
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• 제2권2호
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• pp.58-65
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• 2004

The purpose of this visualization study is to investigate the effect of reduced frequency qualitatively by examining wake patterns for dragonfly flight motion. Dragonflies have two pairs of wing (a forewing and hindwing) and flight is achieved by a pitching and plunging, so it makes a separation over the wings. The separation affects the wake pattern and changed wake pattern has an influence on lift, drag, and propulsion. This experiment was conducted by using a smoke wire technique and a camera fixed above the test section used to take a photograph of the wake. An electronic device is mounted below the test section to find the exact mean positional angle of the wing. The reduced frequency in the experiment is 0.15, 0.3 and 0.45. Results show that reduced frequency is closely related to the wake pattern that determines flight efficiency.