• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.4
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• pp.174-180
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• 2006

The wheel slip control systems are able to control the braking force more accurately and can be adapted to different vehicles more easily than conventional braking control systems. In order to achieve the superior braking performance through the wheel slip control, real-time information such as the tire braking force at each wheel is required. In addition, the optimal target slip values need to be determined depending on the braking objectives such as minimum braking distance, stability enhancement, etc. In this paper, a wheel slip control system is developed for maintaining the vehicle stability based on the braking monitor, wheel slip controller and optimal target slip assignment algorithm. The braking monitor estimates the tire braking force, lateral tire force and brake disk-pad friction coefficient utilizing the extended Kalman filter. The wheel slip controller is designed based on the sliding mode control method. The target slip assignment algorithm is proposed to maintain the vehicle stability based on the direct yaw moment controller and fuzzy logic. The performance of the proposed wheel slip control system is verified in simulations and demonstrates the effectiveness of the wheel slip control in various road conditions.

• Science of Emotion and Sensibility
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• v.7 no.4
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• pp.19-24
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• 2004

The purpose of this study is to evaluate the possibility of identifying joint damping property through commercially available isokinetic ergometer (BIODEX). The proposed method is to estimate the damping torque of the knee joint from the difference between the external joint torque for maintaining isokinetic movement and the gravity torque of the lower leg. The damping torque was estimated at various joint angular velocities, from which the damping property would be derived. Measurement setup was composed of the BIODEX system with an external force sensor and Labview system. Matlab was used in the analysis of the damping property. The experimental result showed that the small variation in angular velocity due to acceleration and deceleration of the crank arm resulted in greater change of inertial torque than the damping torque. Therefore, the estimation of damping property from the isokinetic movement is difficult.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.5
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• pp.343-354
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• 2020

Bi-stable mechanism is a system that has two different stable equilibrium positions within its range of motion. It has an ability to stay in two different positions without external power input and despite small disturbances. One of the most bi-stable applied mechanism is a morphing system, such as deployable structures, switch systems, and robot grippers. However, due to the complexity of mechanism and limitation of structure configuration, it is difficult to apply on a morphing system with rotating link mechanism. In this paper, an implementation method of rotational bi-stable mechanism using cylindrical permanent magnets is proposed. The magnetic field and the magnetic force were calculated from electromagnet model of the cylindrical permanent magnet. Based on the model, the force relation between two links containing the cylindrical permanent magnets was estimated. An array of cylindrical permanent magnets was selected for symmetric bi-stability, and an experiment on the link structure with the proposed bi-stable mechanism was performed to investigate the stability against a external torque.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.1
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• pp.48-55
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• 2011

Hydraulic excavator is one of the most widely used heavy machines in construction sites including dismantling. In the dismantling sites, the excavators equipped with crusher or breaker carry out dangerous operations, so drivers are always exposed to unexpected danger. For safety operation, remote control of the hydraulic excavator has been studied using proportional control valve, which requires an appropriate motion control of its bucket tip. In this case, kinematics and dynamics analysis have to be preceded through modeling of excavator. However, it is difficult to acquire reasonable results from the analysis due to insufficient information of physical parameters such as mass of each links and locations of mass centers, etc. This study deals with the trajectory control of bucket tip, which is based on experimental estimation of cylinder output force. The estimated forces are fed into the control of each cylinder in order to compensate gravitational and frictional effects in the cylinders. The control was applied to horizontal trajectories that are for flattening work.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.117-118
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• 2013

In these days, the world have been increasing navy forces such as aircraft carriers and high-tech destroyers etc. and the importance of submarines is being emphasized. Therefore, accurate values of the derivatives in equations of motion are required to control motion of the submarines. Hydrodynamic coefficients were measured by the vertical planar motion mechanism(VPMM) model test. VPMM equipment gave pure heave and pitch motion respectively to the submarine model and the forces and moments were acquired by load cells. As a result, the hydrodynamic coefficients of the submarine are provided through the fourier analysis of the forces and moments in this paper.

• Journal of the Korean School Mathematics Society
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• v.5 no.1
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• pp.147-155
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• 2002

Jim Libby(2000)는 임의의 M&M 밀크 쵸코렛 봉지에서 꺼낸 것을 다시 집어넣지 않고 3개의 쵸코렛을 꺼낼 때 같은 색이 나올 확률을 계산하는 방법의 논문을 썼다. Libby는 그의 논문에서 갈색, 노랑, 빨강, 주황, 초록, 파랑의 6개 색의 M&M 밀크 쵸코렛들이 똑같은 비율로 분포되었다고 가정하였다. 그러나 실제로 M&M 쵸코렛의 여섯 가지 색깔의 확률분포는 똑같은 비율이 아니다. M&M회사는 홈페이지(http://www.m-ms.com/cai/mms/faq.html)를 통해 실제적인 6개 색의 M&M 밀크 쵸코렛들의 분포는 갈색이 30%, 노랑과 빨간색이 각각 20% 주황, 초록과 파랑은 각각 10%의 분포라고 밝히고 있다. 이 논문에서 우리는 Libby가 생각하였던 문제를 실제적인 6개 색의 M&M 밀크 쵸코렛들의 확률 분표에 의거하여 다시 생각해보며, 또한 3개의 쵸코렛대신 n개의 쵸코렛을 꺼낸다고 가정하여 더욱 일반적인 결론을 유도한다. 또한 유도한 이 정확한 확률 공식과 근사 공식을 활동을 통해 점검하고 학생들이 주도적으로 지금까지 배워온 이론들을 점검할 수 있게 하였다. 활동을 시작하기 전에 정확한 확률 공식과 근사 공식과의 관계를 설명하고 기본적인 확률과 통계의 개념을 다시 정립할 수 있도록 하였다. Piaget가 '지식이란 학습자에 의해 능동적으로 구성되는 것이지 환경으로부터 수동적으로 받아들이는 것은 아니다'라고 했듯이, 활동을 통한 학습은 학생들을 능동적으로 만들기 때문에 학생들이 지식을 구성해 갈 수 있다. 활동을 간단히 소개하면 다음과 같다. 활동I에서는 초코렛을 세어서 근사 확률을 추정하는 방법이 소개된다. 어떻게 매개변수가 두 공식에 관련이 되는지를 측정하고 두 공식을 사용하여 정확한 확률과 근사 확률을 계산하여 비교해본다. 각 조원들과 이 세 과정에서 무엇을 배웠나 토론하고 다른 조들과 배운 것을 나눈다. 활동II는 두 과정으로 나누어진다. 첫 번 과정은 각 그룹의 한 학생이 주어진 쵸코렛 봉지에서 3개의 쵸코렛을 꺼낸다. 다른 학생은 표 3에 나온 결과를 기록한다. 계속하여 20번씩 한다. 다시 학생을 바꾸어 20번 계속한다. 같은 색깔의 쵸코렛이 나온 확률은 계산하기 위한 간단한 실험이고 두 번째 과정은 각 조가 웹사이트나 선생님으로부터 제공받은 프로그램을 다운로드 받아 하는 시뮬레이션이다. 이 실험 후에 학생들이 이 두 활동을 통해 무엇을 배웠는지 토론해보고 또 두 활동을 비교해 볼 수 있다. 마지막으로 M&M 쵸코렛을 먹는 것으로 활동을 마칠 수 있을 것이다. 활동 II에 나오는 두 시뮬레이션은 학생들이 수학 이론의 힘을 깨달을 뿐 아니라 수학 교실에서 큰 재미를 느끼게 될 것이다. 이 논문에서 그래픽 계산기로 할 수 있는 프로그램을 소개하였다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.3 s.108
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• pp.283-290
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• 2006

This study is concerned with static and sinusoidal disturbance rejection for a single periodic input disturbance with known period. In the area of active elimination of a disturbance force, the control input should have two different kinds of gains: one is to deliver a stable control and the other is a force component to cancel the external disturbance force. In this paper we employ a simple state feedback control law to make the balance beam stable and employ a linear observer to estimate the states which represent the external disturbance force components. Simulation results verify our proposed control method to reject a static and sinusoidal disturbance force.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.20 no.2
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• pp.96-104
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• 1984

This paper is on the prediction and response of the ship hull girder due to slamming of foreward flat bottom plate. The response with respect to foreward flat bottom is divided two kinds by estimating method. One is the estimation of impact forces by slamming, Another is the response of hull girder due to impact forces, that is, displacement, velocity, acceleration, etc. must calculate the values for considered ship hull girder. In this paper, therefore, was estimated only impact forces along ship ordinate of foreward. The analysis of data for estimation followed mainly papers of Ochi. These estimated data shall contribute for ship gull construction for basic optimum design. In particular, the estimated impact forces shall be given for the response of ship gull girder on the foreward flat bottom plate with characteristics of external forces.

• Transactions of the KSME C: Technology and Education
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• v.1 no.2
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• pp.205-210
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• 2013

In this research, we have developed a ski-simulation system based on a physics-based simulation model using Newton's second law of motion. Key parameters of the model, which estimates skier's trajectory, speed and acceleration change due to skier's control on ski plate and posture changes, were derived from a field test study performed on real ski slope. Skier's posture and motion were measured by motion capture system composed of 13 high speed IR camera, and skier's control and pressure distribution on ski plate were measured by acceleration and pressure sensors attached on ski plate and ski boots. Developed ski-simulation model analyzes user's full body and center of mass using a depth camera(Microsoft Kinect) device in real time and provides feedback about force, velocity and acceleration for user. As a result, through the development of interactive ski-simulation motion recognition system, we accumulated experience and skills based on physics models for development of sports simulator.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.371-378
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• 2020

Rainfall is one of the most active forces that cause soil erosion. The action of rain on the soil exerts an erosive power caused by the impact of the drops, which fall with variable speed and kinetic energy, depending directly on the diameter of the drop. The objective of this study is to determine algorithms capable of estimating rainfall erosivity for the region of Maceió-AL. For this purpose, erosion rains were collected between 2003 and 2006 using a RD-69 disdrometer, which continuously and automatically measures rainfall distribution in a range of 1 min. The determination of algorithms in the form of power equation to estimate was adjusted with one and two independent variables (amount of rainfall, duration and maximum intensity).