• 시스템엔지니어링학술지
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• 제16권2호
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• pp.110-117
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• 2020

In this paper, we estimated the straight line stability by performing a 3 degree of freedom spiral test simulation of a intact/damaged surface combatant using the hydrodynamic coefficient obtained through the PMM(Planar motion mechanism) test based on system engineering process. A model ship was ONR Tumblehome and damaged compartment was set on the starboard bow. As a result of conducting a spiral test simulation based on the experimental results of J.Ha (2018), the asymmetric straight line stability due to the damaged compartment was confirmed. In the case of a ship in which the starboard bow was damaged, it was confirmed that it had the characteristic to deflect to the left when going straight. Also, when estimating the straight line stability of a both port and starboard asymmetric surface combatant, a separated equation of motion model that sees the port and starboard as different ships seems suitable.

• 대한물리치료과학회지
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• 제24권1호
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• pp.49-58
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• 2017

Purpose: To determine the effect of Functional movement screen(FMS) of Healthy subjects. Method: 18 subjects were randomly assigned toFunctional movement screen test. To measure functional movement screen(deep squat, hurdle step, in line lunge, shoulder mobility reaching, active straight leg raise, trunk stability push up, rotary stability). Result: FMS scores were deep squat 2.61score, right hurdle step 2.67 score, lift hurdle step 2.83 score, in line lunge 2.83 score, right shoulder mobility 2.67 score, left shoulder mobility 2.61 score, right active straight-leg raise 3.00 score, left active straight-leg raise 3.00 score, trunk stability push up 2.33 score, rotary stability 1.94 score. Conclusion: FMS can improve functional movement in healthy adults.

• PNF and Movement
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• 제15권1호
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• pp.67-75
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• 2017

Purpose: The purpose of this study was to determine the effects of a functional movement correction exercise on the functional movement screen scores of badminton players. Methods: The participants consisted of 25 badminton players who were randomly assigned to an experimental group (n = 13) or a control group (n = 12); they engaged in exercise three times per week for eight weeks. The experimental group engaged in the functional movement correction exercise, while the control group engaged in general exercise. An FMS kit (USA) was used to measure the following: FMS score, deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability push up, and rotary stability. Results: The FMS score, deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, and trunk stability push up, and rotary stability showed significant improvement in the experimental group (p < 0.05). Conclusion: The experiment confirmed that the functional movement screen scores of badminton players improve with effective exercise interventions.

• PNF and Movement
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• 제14권1호
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• pp.23-32
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• 2016

Purpose: The purpose of this study was to determine the effects of a coordinative locomotor training program on the functional movement screen (FMS) scores of badminton players. Methods: The participants consisted of 31 badminton players who were randomly assigned to either an experimental group (n=15) or a control group (n=16), and engaged in exercise five times per week for six weeks. The experimental group engaged in coordinative locomotor training and the control group engaged in general exercise. An FMS kit (USA) was used to measure the following: FMS score, deep squat, hurdle step, in-line lunge, shoulder mobility, active straight leg raise, trunk stability push up, and rotary stability. Results: The FMS score, deep squat, hurdle step, in-line lunge, active straight leg raise, and trunk stability push up showed significant improvement in the experimental group (p<0.05). Conclusion: The coordinative locomotor training program was able to produce confirmation that functional movement screen scores change in the case of effective exercise interventions in badminton players.

• 대한조선학회논문집
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• 제52권6호
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• pp.494-500
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• 2015

It has been reported that a ship sailing in shallow water possesses better straight-line stability due to the change of fluid flow around the ship. This tendency affects manoeuvring characteristics of the ship. To investigate this phenomenon, indoor free running model test(FRMT) on KVLCC2 was carried out in three water depth conditions(H/T = 1.2, 1.5 & 2.0). Turning circle tests(± 35° ) and zigzag tests(± 20° /5° and ± 20° /10° ) were conducted with newly developed indoor FRMT system, and the manoeuvring results were compared with test results from other institutes. As the water depth decreased, the yaw rate of the ship decreased, and the distances of circular trajectories at the same heading angle increased in the turning circle tests. The first overshoot angles of the zigzag tests decreased. From both tests, the time for course change increased as the water depth decreased. These manoeuvring characteristics show that KVLCC2 in shallow water becomes more stable in terms of straight-line stability.

• 제어로봇시스템학회논문지
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• 제18권2호
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• pp.141-148
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• 2012

This paper proposes fault tolerant gaits of a quadruped robot with feet of flat shape. Fault tolerant gaits make it possible for a legged robot to continue static walking against a leg failure. In the previous researches, it was assumed that a legged robot had feet that have point contact with the surface. When the robot is endowed with feet having flat shape, fault tolerant gaits can show better performance compared with the former gaits, especially in terms of the stride length and gait stability. In this paper, fault tolerant gaits of a quadruped robot against a locked joint failure are addressed in straight-line motion and crab walking, respectively.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.761-765
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• 1997

Our study of rider's postulator stability and tracking control on a unicycle began form the observation of a human riding. The system including unicycle and human operationg his unicycle is a fuzzy intelligent biomechanical model on basis of instinct and intuition search mechanisms. We proposed a robotic unicycle with one wheel and one body as a basic mode and derived equation of motion to this model. Our works is in making out fuzzy look-up table to control robotic unicycle. Fuzzy look-up table were determined for staight line and curve under reasonable inference emulating human's instinct and intuition riding a unicyale. Simulation results show that postulator stability and tracking control on both straight line and curve were successful by using proposed each fuzzy look-up table.

• 한국항해학회지
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• 제10권2호
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• pp.97-114
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• 1986

Ship's maneuverability is very important factor in safe ship handling and economical ship operation. Steering characteristics are consisted of course stability and maneuverability. Today in many advanced ship-building countries, they study ship's course stability, using model ship tests, such as straight line tests, rotating arm tests and Planar Motion Mechanism (PMM) etc., in tow in tanks. It is the purpose of this paper to provide ship's handlers with better understanding of steering characteristics and to help them in safe controlling and manevering . In this paper, the author simulated response of various vessels, running straight course with constant speed, and they are disturbed by small external disturbance of one degree yaw angle with no angular velocity . The author used the hydrodynamic derivtives resulted at tests of Davidson's laboratory in Stevens Institute of Technology, New Jersey, U.S.A. Course stability was evaluated and analyzed in various respects, such as block coefficient, ratio of ship's length to beam, draft and rudder area ratio etc. The obtained results are as follows : (1) The ship's course stability is affected by magnitude of block coefficient greatly. In case that the block coefficient is more than 0.7, the deviation varies at nearly same rate but the requistite time to reach the steady course is different. (2) The ship's course stability is affected by magnitude of L/B. When the dimensionless time reaches about 3, the deviation and requisite time to reach the steady course are influenced nearly same. After the dimensionless time is about 3, they change on invariable ratio. (3) The effect to course stability by L/T and RA' can be neglected. (4) The reason why thy VLCC and container feeder vessel are unstable on their course is that their block coefficient is generally more than 0.8 and the ratio of ship's length to beam is about 6.0.

• 한국지반신소재학회논문집
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• 제16권4호
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• pp.83-92
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• 2017

본 논문은 보강토옹벽의 곡선부 거동을 수치해석으로 분석한 내용을 다루고 있다. 보강토옹벽은 토목섬유의 발전과 함께 발달해왔다. 기존의 콘크리트 옹벽과 달리 성토 높이에 제약을 받지 않고 안정성을 확보할 수 있다는 장점이 있으며, 현재 산업 및 주거단지를 형성하는데 많이 사용되고 있다. 이러한 보강토옹벽의 설계는 현재 다른 형식의 옹벽 설계와 동일하게 내 외적 안정성 검토 및 보강재의 인장력에 대한 검토를 활용하여 이루어지고 있으며, 주로 2차원 수치해석을 바탕으로 이루어지고 있다. 그러나 기존의 연구결과에 따르면, 보강토옹벽의 취약부는 곡선부로 보고되고 있으며, 이는 실내모형시험 및 피해사례에 대한 연구에서 언급된 바 있다. 보강토옹벽의 곡선부 거동을 파악하기 위한 2차원 수치해석은 그 한계점을 분명히 드러내고 있으며, 실내모형시험 및 현장시험 또한 그 거동과 파괴메커니즘을 이해하기에는 그 한계를 갖고 있다. 따라서 본 연구에서는 보강토옹벽의 곡선부의 거동을 이해하기 위해 3차원 수치해석을 수행하였으며, 수치해석에서의 직선부와 곡선부의 결과를 비교 분석하였다. 뿐만 아니라, 상재하중의 고려 여부 및 성토체의 다짐도를 달리하여 각각의 조건에서의 거동특성을 비교 분석하였다.

• International Journal of Automotive Technology
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• 제7권2호
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• pp.187-193
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• 2006

When emergency evasion during running is required, a driver sometimes causes a vehicle to drift, that is, a condition in which the rear wheels skid due to rapid steering. Under such conditions, the vehicle enters a very unstable state and often becomes uncontrollable. An unstable state of the vehicle induced by rapid steering was simulated and the effect of differential steering assistance was examined. Results indicate that, in emergency evasion while cornering and during which the vehicle begins to drift, unstable behavior like spins can be avoided by differential steering assistance and both the stability and control of the vehicle is improved remarkably. In addition, reduction of overshoot during spin evasion by the differential steering assistance has been shown to enable the vehicle to return to a state of stability in a short time in emergency evasion during straight-line running. Moreover, the effectiveness of differential steering assistance during emergency evasion was confirmed using a driving simulator.