• Journal of Advanced Marine Engineering and Technology
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• 제22권6호
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• pp.862-870
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• 1998

In this paper an experimental investigation of characteristics of developing transitional unsteady flows in a square-sectional 180。 curved duct are presented. The experimental study using air is carried out to measure axial velocity profiles secondary flow velocity profiles and entrance length by using Laser Do ppler Velocimeter(LDV) system. The flow development is found to depend upon Dean number dimensionless angular frequency velocity amplitude ration and cur-vature ratio. Of special interest is the secondary flow generated by centrifugal effects in the plane of the cross-section of the duct. The secondary flows are strong and complicate at entrance region. The entrance length of transitional pulsating flow is obtained to 120。 of bended angle of duct in this experimental conditions.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2227-2229
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• 2003

Using the gyro effect, Balance Beam Controller is developed with Samsung Corporation. Balance Beam Controller is possible to control the position of an object in air by controlling the attitude of inner gimbal. But in the unknown load inertia case, even a skilled worker it is not easy to operate a Balance Beam. That is caused by the difficulty to estimate the load inertia. If the amount of the gimbal operation is set excessively with a wrong load estimation, it can often cause accidents. To solve this problem, the control function which is revolving with velocity of the revolution has to be added to developed equipment. In this research, we analyze the characteristics of a Balance Beam(the smaller load inertia, the bigger force of restitution) using the angular velocity sensor, and present constant velocity revolving controller with estimating value of the load using this moving characteristics.

• Interaction and multiscale mechanics
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• 제5권2호
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• pp.105-114
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• 2012

The study of rigid roadway pavement under dynamic traffic loads with variable velocity is investigated in this paper. Rigid roadway pavement is modeled as a rectangular damped orthotropic plate supported by elastic Pasternak foundation. The boundary supports of the plate are the steel dowels and tie bars which provide elastic vertical support and rotational restraint. The natural frequencies of the system and the mode shapes are solved using two transcendental equations, obtained from the solution of two auxiliary Levy's type problems, known as the Modified Bolotin Method. The dynamic moving traffic load is expressed as a concentrated load of harmonically varying magnitude, moving straight along the plate with a variable velocity. The dynamic response of the plate is obtained on the basis of orthogonality properties of eigenfunctions. Numerical example results show that the velocity and the angular frequency of the loads affected the maximum dynamic deflection of the rigid roadway pavement. It is also shown that a critical speed of the load exists. If the moving traffic load travels at critical speed, the rectangular plate becomes infinite in amplitude.

• 한국융합학회논문지
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• 제13권5호
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• pp.287-294
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• 2022

본 연구는 스포츠 현장에서 부상예방으로 많이 사용되고 있는 탄력 테이핑을 슬관절 굴곡과 신전에 적용하여 근력, 근파워, 근지구력에 미치는 영향을 검증하기 위해 진행하였다. 연구 대상자는 슬관절의 굴곡과 신전 운동에 이상이 없는 남자 대학생 10명으로 하였다. 측정방법은 등속성근기능측정 장비를 활용하여 슬관절 굴근과 신근에 키네시오 테이핑을 적용 전, 후로 각속도 60°/sec 5회, 180°/sec 5회, 240°/sec 25회를 측정하였다. 연구결과는 슬관절 신전 시 키네시오 테이핑 적용 전보다 후에 우측 각속도 180°/sec에서 Average Power가 유의하게 증가하였다(p=.010). 슬관절 굴곡 시 키네시오 테이핑 적용 전보다 후에 우측 각속도 180°/sec에서 Average Power가 유의하게 증가하였다(p=.016). 또한 각속도 240°/sec에서는 Total Work Done에서 좌(p=.002), 우(p=.002) 모두 유의하게 증가하였다. 대퇴직근과 대퇴이두근에 키네시오 테이핑 적용이 슬관절 운동 시 근파워과 근지구력을 향상시키는 보조적인 영향이 긍정적으로 나타났다.

• 한국자기학회지
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• 제6권1호
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• pp.48-53
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• 1996

자이로스코프에서 기울어진 회전자를 바로 세우는 역할을 하는 것이 토커이다. 본 연 구에서는 최대입력각속도 조건을 만족하면서 주어진 자석성능으로 최대의 특성을 낼 수 있는 설계에 대하여 알아보고자 한다. 자이로스코프의 기계적 치수가 결정되면 토커의 치수는 제한된다. 즉 코일이 위치하는 공간이 제한되므로 코일의 굵기가 결정되면 권선수도 정해지게 된다. 이 치수들을 이용하여 토커의 환산계수를 계산한 후, 코 일에 흐를 수 있는 최대 전류를 계산하면, 최대 입력각속도가 계산되어진다. 토커의 특성해석은 3차원 유한요소법을 이용하였으며, 유한요소 해석 결과로부터 토커의 환산 계수를 계산하였다. 실제 제작한 자이로의 성능실험을 통하여 제안된 토커 설계 알고리즘의 유용함을 입증한다.

• 한국운동역학회지
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• 제24권1호
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• pp.11-18
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• 2014

The purposes of this study were to analyze the kinematics and electromyographic variables of the upper extremity for the backhand clear motion according to the type of hitting in badminton. Seven elite male university players were selected as the subjects. Four digital video cameras and Noraxon Telemyo 2400 were used to collect the 3D kinematics and electromyographic data. The results were as follows: 1) in the phase of impact, the time of motion for the overhead backhand clear was the longest, 2) in the event of impact, the distance of step toward X direction was the longest and the distance of step toward Y direction was the shortest for the overhead backhand clear, 3) in the event of backswing, the rotation angles of shoulder and pelvis and the flexion angle of shoulder for the overhead backhand clear were the biggest, 4) the maximum flexion angular velocity of shoulder and the maximum extension angular velocity of elbow for the overhead backhand clear were the biggest, and 5) in the phase of impact, mean EMG of the wrist flexor, triceps, and trapezius muscle for the overhead backhand clear was bigger than that for the underhand stroke and in the phase of follow-through, mean EMG of the wrist flexor and extensor, biceps, triceps, and trapezius muscle for the overhead backhand clear was the biggest.

• 한국자동차공학회논문집
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• 제20권3호
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• pp.58-66
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• 2012

This paper describes a design and a verification of linear state observers for a motorized seat belt system to estimate state information such as angular velocity and load torque. The motorized seat belt system provides functions to protect passengers and improve passenger's convenience. To realize these functions, sensors which can measure an angular velocity and load torque are needed. By use of the linear state observer, state information can be estimated without sensors. The motorized seat belt system is analysed and represented as a state space model which contains load torque as an augmented state. By the developed state space model, a full and reduced order observer are designed and verified by experiments. The full and reduced order observer are also compared from points of view of execution time and noise robustness.

• Journal of Biosystems Engineering
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• 제36권6호
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• pp.422-433
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• 2011

Market demand for hydro-mechanical transmission (HMT) for agricultural tractors has increased recently. To select a type of HMT satisfying design conditions, performance characteristics of 12 HMT types must be understood. This study was conducted to provide tractor engineers with a guideline to select the most appropriate HMT type for their design requirements. Characteristics on speed reduction ratio, power transmission efficiency, power regeneration, lock-up angular velocity, output torque ratio and torque ratio of planetary gear train axis of the 12 HMT types were investigated and presented as either formula or graphical forms. A guideline to select proper HMT type was also presented using 2 parameter: lock-up angular velocity (${\omega}_L$) and torque ratio of the planetary gear train axis. In addition, effect of gear ratio of the planetary gear train on the power transmission efficiency was investigated and a guideline to select the best gear ratio was also presented.

• 한국운동역학회지
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• 제22권2호
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• pp.253-259
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• 2012

The purpose of this study was to determine how smartphone use posture affects biomechanical variables and muscle activities. Eleven university students(age: $22.2{\pm}2.6$ yrs, height: $176.6{\pm}4.7$ cm, weight: $69.5{\pm}7.5$ kg) who have no musculoskeletal disorder were recruited as the subject according to having experience in using the smartphone for more than one year. Angular velocity, muscle activity, and thumb finger pressure were determined for each trial. For each dependent variable, a one-way analysis of variance (ANOVA) with repeated measures was performed to test if significant difference existed among different three conditions (p<.05). The result showed that rotational angular velocity of the first metacarpal were increased in DESK posture compared with STAND posture during SU phase. The average nEMG values of FDI(First dorsal interosseous) were less in SIT and DESK posture compared with STAND posture during SR phase. These indicated that smartphone postures may effect the thumb ROM(Range of motion) and muscle activity. This has led to suggestions of the need for further kinetic and EMG analyses to evaluate best assess and characterize with smartphone use.

• 대한물리치료과학회지
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• 제3권3호
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• pp.51-56
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• 1996

Isokinetic test of muscle strength was performed on 20 patients operated laminectomy & discectomy. Peak torque of ankle dorsi flexors & plantar flexors at the angular velocity of $30^{\circ}$/sec and average power and total work of ankle dorsi flexors & plantar flexors at the angular velocity $90^{\circ}$/sec were measured and analyzed. The result were as follows: 1. Peak torque of non - dominant dorsi flexors at $30^{\circ}$/sec showed no significant difference statistically, but dominant dorsi flexors at $30^{\circ}$/sec showed significant difference statistically(p<0.05). 2. Peak torque of dominant & non - dominant plantar flexors at $30^{\circ}$/sec showed significant difference statistically(p<0.05). 3. Average power of dominant & non - dominant dorsi flexors at $90^{\circ}$/sec showed no significant difference statistically. 4. Average power of dominant & non - dominant plantar flexors at $90^{\circ}$/sec showed significant difference statistically (p<0.05). 5. Total work of dominant & non - dominant dorsi flexors at $90^{\circ}$/sec showed no significant difference statistically. 6. Total work of dominant & non - dominant plantar flexors at $90^{\circ}$/sec showed significant difference statistically(p<0.05).