• 한국화재소방학회논문지
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• 제15권1호
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• pp.41-46
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• 2001

수평 평판과 충돌하는 제트에 의해 생성되는 연기유동을 관찰하기 위해 질소가스네 kerosene 연기입자를 띄워 유동장을 가시화하였다. 광원으로는 아르곤-이온 레이져 평면광이 사용되었다. Kerosene smoke의 산란 광에 의한 수직평면 상(image)과 수평평면 상을 고속 CCD 카메라와 비디오 카메라로 녹화하였으며, 얻어진 영상으로부터 연기선단의 순간속도 및 평균속도를 측정하였다.

• 한국측량학회지
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• 제38권5호
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• pp.401-406
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• 2020

Continuously monitoring of Horizontal and Vertical movements in vulnerable areas due to earthquakes and volcanic activities is vital. These geohazard activities are the result of a slow deformation rate at the tectonic plate boundaries. The recent development of GPS (Global Positioning System) technology has made it possible to attain a millimeter level changes in the Earth's crust. This study used continuously observed GPS data at the flank of Ol Doinyo Lengai volcanic Mountain to determine crustal motion caused by impinging volcano from mantle convention. We analyzed 8 GPS observed from June 2016 to Dec 2019 using a well-documented Global Kalman Filter GAMIT/GLOBK software. The resulting velocity from GAMIT/GLOBK analysis was then used to compute the relative motion of our study area with respect to Nubia plate. Our analysis discovered a minor motion of less than 5mm/year in both horizontal and vertical components.

• 대한기계학회논문집
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• 제18권1호
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• pp.175-183
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• 1994

To investigate thermophoretic effect on particle deposition, average deposition velocity toward a horizontal wafer surface in vertical airflow is measured keeping the wafer surface temperature different from the surrounding air temperature. In the present measurement, the temperature difference is maintained in the range from -10 to $4^{\circ}$ C Polystyrene latex (PSL) spheres of diameter between 0.3 and 0.8 .mu.m are used for the experiment. The number of particles deposited on a wafer surface is estimated from the measurements using a wafer surface scanner (PMS SAS-3600). Experimental data are compared with prediction model results.

• 전기학회논문지
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• 제67권10호
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• pp.1395-1400
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• 2018

EO TGP(Electro-Optical Targeting Pod) is an optical tracking system which has various functions such as target tracking and image stabilization and LOS(Line of Sight) change. Especially, it is very important to move the LOS into a interest point for joystick command. When pilot move joystick in order to observe different scene, EO TGP gimbals should be operated properly. Generally, most EOTS just operate corresponding gimbal for joystick command. For example, if pilot input horizontal command in order to observe right hand screen, it just drive azimuth gimbal at any position. But in the screen, the image dosen't move in a horizontal direction because gimbal structure is Euler angle. And image rotation is occurred by elevation gimbal angle. So we need to move Pitch gimbal. So in the paper, we designed LOS moving algorithm which convert LOS command to gimbal velocity command to move LOS properly. We modeled a differential kinematic equation and then change the joystick command into velocity command of gimbals. This algorithm generate velocity command of each gimbal for same horizontal direction command. Finally, we verified performance through MATLAB/Simulink.

• 한국운동역학회지
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• 제15권3호
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• pp.133-142
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• 2005

The purpose of this study was to compare of the kinematic variables from takeoff preparation to takeoff used by long jumpers who recorded over 8meters in 2002 Busan Asian Game and 2003 Daegu Universiade and 2001 national championship. The kinematic characteristics from the last three stride to takeoff at the takeoff board were analyzed such as velocities, heights and angles. The conclusion were as follows; In order to record over 8meters the national long jumpers should have under 5cm height variation at the penultimate stride of the run-up. In the approach phase the horizontal velocity of the jumpers should reach to 10m/s in touchdown at takeoff board The vertical velocity must have 3.75m/s simultaneously in order to record 8meters. The jumpers need to continue talent of the horizontal velocity in touchdown at takeoff board and require jumping power of the takeoff leg at takeoff board The appropriate body variation range ratio between takeoff and touchdown should be 1.2 vs 1 and the trunk angle at touch down on the board should be close to the erect posture for higher body flight.

• 한국전산유체공학회지
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• 제3권1호
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• pp.73-81
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• 1998

The effect of vertical or horizontal throughflow on natural convection in horizontal porous layer was investigated. The computations were performed by employing Darcy-Brinkman-Forchheimer equation to consider the effect of inertia and viscous effect. The patterns of streamlines and isotherms are observed by changing the strength of throughflow. The vertical throughflow stabilizes the natural convection in porous layer. It also disturbs the developing vertical and horizontal velocity component of natural convection cell and increases the critical modified Rayleigh number. The horizontal throughflow influences the stabilization of natural convection in porous layer much more than the vertical throughflow. And it changes a stable convection into a oscillatory convection.

• 콘크리트학회논문집
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• 제13권5호
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• pp.423-429
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• 2001

본 연구에서는 초기양생 중에 수평연속진동을 받는 콘크리트 시험체에 대하여 강도특성이 조사되었다. 실험변수로서 진동속도(0.25, 0.5, 1, 2, 4 kine)와 진동가력시간(3, 6, 12, 24 hrs)을 택하였다. 압축강도, 쪼갬인장강도 및 부착강도가 비교되었으며, 밀도와 재료분리현상이 조사되었다. 실험 결과, 진동속도 0.25 kine에서는 진동가력시간에 관계없이 모든 시험체에서 강도의 감소가 거의 발생하지 않았고, 또한 진동속도 0.5 kine에서 3시간의 진동을 받은 경우에도 강도의 감소가 없었다. 전체 시험체에 있어서 밀도가 증가하였으며, 재료분리현상은 발견되지 않았다.

• Journal of Biosystems Engineering
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• 제43권3호
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• pp.194-201
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• 2018

Purpose: The objective of this study was to propose a formula for the theoretical grain mean transport velocities of an elliptically moving oscillator by modifying the grain mean transport velocity formula applied to linear motion and to compare the calculated values with the experimental values of grain mean transport velocity. Methods: The values of the throwing index ($K_v$) and the maximum horizontal velocities for various positions on the elliptical oscillator were obtained using kinematic analysis. To obtain the actual grain transport velocity, the mean transport velocities of perilla grains at six positions on the sieve surface were measured using a high-speed camera and compared with the theoretical values. The cam with an eccentric bearing on the oscillator was designed to be eccentric by 1.6 cm so that the lengths of the major axis of the elliptical motion were 3.2-3.6 cm. The material used in the experiments was perilla grain. Results: The experimental result was consistent with the theoretical value calculated using the proposed formula ($R^2$ is 0.80). It is considered that the angle difference between the maximum accelerations in the directions vertical and horizontal to the sieve has as much influence on the grain mean transport velocity as the value of Kv itself. Conclusions: It was possible to theoretically obtain the grain mean transport velocities through a screening device in elliptical motion by modifying the formula of the grain mean transport velocities used in linear motion.

• Geomechanics and Engineering
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• 제24권2호
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• pp.143-156
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• 2021

Rail transit lines usually pass through many complicated topographies in mountain areas. The influence of inclined bedrock on the train-induced soil vibration response was investigated. Model tests were conducted to comparatively analyze the vibration attenuation under inclined bedrock and horizontal bedrock conditions. A three-dimension numerical model was built to make parameter analysis. The results show that under the horizontal bedrock condition, the peak velocity in different directions was almost the same, while it obviously changed under the inclined bedrock condition. Further, the peak velocity under inclined bedrock condition had a larger value. The peak velocity first increased and then decreased with depth, and the trend of the curve of vibration attenuation with depth presented as a quadratic parabola. The terrain conditions had a significant influence on the vibration responses, and the inclined soil surface mainly affected the shallow soil. The influence of the dip angle of bedrock on the peak velocity and vibration attenuation was related to the directions of the ground surface. As the soil thickness increased, the peak velocity decreased, and as it reached 173% of the embedded pile length, the influence of the inclined bedrock could be neglected.

• 한국운동역학회지
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• 제15권4호
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• pp.143-151
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• 2005

This study was conducted to investigate the technical factors of Cuervo forward straight vaults with single twist, single and half twists, and double twists actually performed by three execellent male gymnasts participated in artistic gymnastics competition of 2003 summer Universiade in Daegu and the 85th National Sports Festival in Cheongju. To accomplish the research goals the Cuervo vaults of three gymnasts were filmed by using three digital camcorders set by 60 Hz, and data were collected through the DLT method of three dimensional cinematography. The kinematic and kinetic variables as each phasic time, CM displacement velocity, release angle inclination angle hip joint angle landing angle, average horse reaction force average moment arm average torque, whoe body's total remote local angular momentum were analyzed, so the following conclusions were reached. Generally to perform the better Cuervo vault, a gymnast should touch down on the board with the great horizontal velocity of the whole body through the fast run-up, and touch down on the horse by decreasing the horizontal displacement of the whole body during the preflight, so raise CM height gradually within a short horse contact time. He should increase the horse reaction force through checking the horizontal velocity of the whole body effectively and the inclination angular displacement of the handstand, if so he can have the large vertical velocity of the whole body. By using the acquired the velocity and the angular momentum of the whole body, he can vault himself higher and twist sufficiently, then he can get better if the body could be tilted by swinging both arms and perform the cat twist with a little flexions at hip joints. According to the above outcomes we can judge that the best athletes is LuBin, the better is YTY, and the next is JSM.