• Journal of the Korean Institute of Intelligent Systems
• /
• v.25 no.3
• /
• pp.236-241
• /
• 2015

This paper presents a study on transformable multiple quadruped robots by docking between robots and waist joints. This robot is able to go on a variety of angles because of mecanum wheels. It is also a hybrid design which allows robot use legs to overcome obstacles on complex terrains and wheels to move on flat ground. The robot is applied kinematics of mecanum wheels and walking, and its walking is based on specific patterns. Docking module is located in front and backside of robot, docking algorithm is suggested and fulfilled for docking between 2 robots. A waist joint is at the center of robot body for transformation and after docking and transformation, robot can activate new functions that carry something.

• Journal of Advanced Marine Engineering and Technology
• /
• v.37 no.6
• /
• pp.603-610
• /
• 2013

Finite element analysis is performed to evaluate stress and deformation of a wrinkle-type dust cover for the ball joints of tie rods of automotive steering system. Results of the analysis for assembly and operation condition show that sealing capability is good and the maximum stress on the body is smaller than the tensile strength. An optimal shape of the dust cover is obtained using the Taguchi method to reduce the maximum stress. The maximum stress of the optimal design under the operation condition is reduced by 22 per cent of that of the initial design. Results of the research show that performance evaluation and design of the dust covers can be effectively done using the proposed method.

• Korean Journal of Applied Biomechanics
• /
• v.20 no.1
• /
• pp.57-65
• /
• 2010

Korean traditional martial arts Taekkyon has a unique stepping method, Poombalbki. The purpose of this study was to investigate kinematic factors and ground reaction forces on two types of Poombalbki, one of which use knee bending and the other use chiefly hip bending. Six male taekkyoners who are the students of Y University participated in this study. Positions and velocities of CoM, the elapsed times of each phase, angles and angular velocities of low limb joints, and GRFs were analyzed for this study. The results were as follows; CoMs of whole body, trunk, and head were more posteriorly positioned in performing hip bending Poombalbki than knee bending one. Horizontal velocities of those were slower in performing hip bending Poombalbki. A player stayed more shortly within range of his opponent in performing hip bending Poombalbki. The vertical and horizontal components of GRF of forward-stepping foot were smaller in performing hip bending Poombalbki(p<.05). In conclusion hip bending is useful strategy, because A player is farther from his opponent, he stayed more shortly within range of his opponent, and the smaller weight is loaded on his front foot in performing hip bending Poombalbki than knee bending one.

• Journal of Korean Society of Transportation
• /
• v.20 no.2
• /
• pp.81-92
• /
• 2002

An automobile crash with a pedestrian generates a trajectory which is crucial to identify the cause of the crash. Previous researches have been carried out for pedestrian movement using simple explicit formulae. The formulae are derived from elementary physics. Therefore, they could not sufficiently include variables of a vehicle and a pedestrian. To overcome such a limitation, a simulation is utilized for the pedestrian behavior in crash environment. A dynamic software called MADYMO is utilized for the simulation. A simulation model is established. The automobile body and a dummy are modeled with rigid bodies, joints and springs. The simulation results are compared with those from explicit formulae. It is found that the explicit formulae did not fit to pedestrian conditions. Simulations are performed for various velocities of automobiles. Results are discussed for the usage of the simulation.

• Journal of the Ergonomics Society of Korea
• /
• v.21 no.2
• /
• pp.35-46
• /
• 2002

This study was performed to determine the voluntary range of joint mobility for middle-aged Korean adults. One hundred and eighty-eight subjects(99 males and 89 females) at the age range of 40 to 60 participated for this study. Thirty body movements at various joints were conducted to measure the range of joint mobility. Subjects were grouped by Rohrer's into four based on 25th percentile. The data were analyzed to see the differences of range of joint mobility between sexes and Rohrer's index groups. The results of this study and previous studies were compared to see the differences of range of joint mobility due to the aging. Results of this study indicate that females are generally more flexible than males. Significant differences were found to exist in fourteen movement between sexes and in ten movements, females have larger range of joint mobility than males. There were no significant differences in range of joint mobility may have a tendency to decrease with ages. The results of this study provide important information in dynamic dimensions for middle-aged Korean and can be used to design the various and work places for the middle-aged.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1160-1165
• /
• 2004

The purpose of this study was to calculate three dimensional angular displacements, moments and joint reaction forces of the ankle joint during the waist pulling, and to assess the ankle joint reaction forces according to different perturbation modes and different levels of perturbation magnitude. Ankle joint model was assumed 3-D ball and socket joint which is capable of three rotational movements. We used 6 cameras, force plate and waist pulling system. Two different waist pulling systems were adopted for forward sway with three magnitudes each. From motion data and ground reaction forces, we could calculate 3-D angular displacements, moments and joint reaction forces during the recovery of postural balance control. From the experiment using falling mass perturbation, joint moments were larger than those from the experiment using air cylinder pulling system with milder perturbation. However, JRF were similar nevertheless the difference in joint moment. From this finding, we could conjecture that the human body employs different strategies to protect joints by decreasing joint reaction forces, like using the joint movement of flexion or extension or compensating joint reaction force with surrounding soft tissues. Therefore, biomechanical analysis of human ankle joint presented in this study is considered useful for understanding balance control and ankle injury mechanism.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.681-685
• /
• 2004

A media-feeding (or media-transport) system is a key component in daily consumer systems such as printers, copiers and ATM's. The role of the media-transport system is to feed a medium, which is usually in the form of a thin film, to the main process in a uniform and repeatable manner. Even small slippage between the media and the feeding rollers could significantly degrade the performance of the entire system. The slippage between the medium and the feeding rollers is determined by many parameters which include the friction coefficient between the feeding rollers and the medium material, the angular velocity of the feeding rollers, and the normal force applied by feeding rollers on the medium. This paper investigates the effect of the normal force and the angular velocity of feeding rollers on the slippage of the medium. Authors have constructed a test bed for experiments, which consists of a feeding module and various measuring devices. Using regular paper as media being fed, the authors experimentally measured the slippage of the medium under various normal forces and angular velocities of driving feeding roller. Also the authors developed a novel two-dimensional simulation model for the media-transport system. The paper medium is modeled as a set of multiple rigid bodies interconnected by revolute joints and rotational springs and dampers. Simulations were executed using a multi-body dynamic analysis tool called RecurDy $n^{ⓡ}$. The slippage obtained by the simulation is compared to experimental results.ults.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1994.04a
• /
• pp.561-568
• /
• 1994

A man model can be used as an effective tool to design ergonomically sound products and workplaces, and subsequently evaluate them properly. For a man model to be truly useful, it must be integrated with a posture prediction model which should be capable of representing the human arm reach posture in the context of equipments and workspaces. Since the human movement possesses redundant degrees of freedom, accurate representation or prediction of human movement was known to be a difficult problem. To solve this redundancy problem, a psychophysical cost function was suggested in this study which defines a cost value for each joint movement angle. The psychophysical cost function developed integrates the psychophysical discomfort of joints and the joint range availability concept which has been used for redundant arm manipulation in robotics to predict the arm reach posture. To properly predict an arm reach posture, an arm reach posture prediction model was then developed in which a posture configuration that provides the minimum total cost is chosen. The predictivity of the psychophysical cost function was compared with that of the biomechanical cost function which is based on the minimization of joint torque. Here, the human body is regarded as a two-dimensional multi-link system which consists of four links ; trunk, upper arm, lower arm and hand. Real reach postures were photographed from the subjects and were compared to the postures predicted by the model. Results showed that the postures predicted by the psychophysical cost function closely simulated human reach postures and the predictivity was more accurate than that by the biomechanical cost function.

• Journal of Korea Multimedia Society
• /
• v.10 no.6
• /
• pp.716-725
• /
• 2007

In this paper we describe a motion tracking algorithm for 3D human animation using stereo vision system. This allows us to extract the motion data of the end effectors of human body by following the movement through segmentation process in HIS or RGB color model, and then blob analysis is used to detect robust shape. When two hands or two foots are crossed at any position and become disjointed, an adaptive algorithm is presented to recognize whether it is left or right one. And the real motion is the 3-D coordinate motion. A mono image data is a data of 2D coordinate. This data doesn't acquire distance from a camera. By stereo vision like human vision, we can acquire a data of 3D motion such as left, right motion from bottom and distance of objects from camera. This requests a depth value including x axis and y axis coordinate in mono image for transforming 3D coordinate. This depth value(z axis) is calculated by disparity of stereo vision by using only end-effectors of images. The position of the inner joints is calculated and 3D character can be visualized using inverse kinematics.

• Journal of Chest Surgery
• /
• v.41 no.6
• /
• pp.799-802
• /
• 2008

Infection occurs very rarely in the sternoclavicular joint compared to other joints in the body. It occurs mainly in IV drug abusers, diabetics, chronic renal failure patients, septic patients and those with central vein catheters. In the early phase, it can be treated simply by antibiotics or incision, and drainage. However, when proper treatment is not begun. early, bone destruction can occur, and only en-bloc resection of the involved bone can cure it. To reduce the risk of recurrence, we advanced a pectoralis major flap into the resected area based on the feeding artery. We report a case of a patient with sternoclavicular osteomyelitis who was successfully treated using en-bloc resection and a pectoral advancement flap.