• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.3
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• pp.261-266
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• 2002

Up to now a wide variety of researches on inpipe robots for inspection have been introduced, but it still seems to be difficult to construct a robot providing mobility sufficient to navigate inside the complicated configuration of underground pipelines. The robot for the inspection of pipelines should freely move along the basic configuration of pipelines such as along horizontal or vertical pipelines. Moreover it should be able to travel along reducers and elbows, and especially the capability for steering in branches is essential to it. In this report, citical points and technologies in the development of the inpipe inspection robots are introduced and inpipe robots developed for last several years are introduced.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1418-1425
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• 2014

In ultrasonic medical imaging, spatial compounding of images is a technique where ultrasonic beam is steered to examine patient tissues in multiple angles. In the conventional ultrasonic diagnostic imaging, the steering of the ultrasonic beam is achieved electronically using the phased array transducer elements. In this paper, a spatial compounding approach is presented where the ultrasonic probe element is rotated mechanically and the beam steering is achieved mechanically. In the spatial compounding, target position is computed using the value of the rotation axis and the transducer array angular position. However, in the process of the rotation mechanism construction and the control system there arises the inevitable uncertainties in these values. These geometric parameter errors result in the target position error, and the consequence is a blurry compounded image. In order to reduce these target position errors, we present a spatial compounding scheme where error correcting transformation matrices are computed and applied to the raw images before spatial compounding to reduce the blurriness in the compounded image. The proposed scheme is illustrated using phantom and live scan images of human knee, and it is shown that the blurriness is effectively reduced.

• The Journal of Korea Robotics Society
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• v.6 no.4
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• pp.323-333
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• 2011

Due to the limited pendulum motion range, the conventional one-pendulum driven spherical robot has limited driving capability. Especially it can not drive parallel direction with center horizontal axis to which pendulum is attached from stationary state. To overcome the limited driving capability of one-pendulum driven spherical robot, we introduce a spherical robot, called KisBot II, with a new type of curved two-pendulum driving mechanism. A cross-shape frame of the robot is located horizontally in the center of the robot. The main axis of the frame is connected to the outer shell, and each curved pendulum is connected to the end of the other axis of the frame respectively. The main axis and pendulums can rotate 360 degrees inside the sphere orthogonally without interfering with each other, also the two pendulums can rotate identically or independent of each other. Due to this driving mechanism, KisBot II has various motion generation abilities, including a fast steering, turning capability in place and during travelling, and four directions including forward, backward, left, and right from stationary status. Experiments for several motions verify the driving efficiency of the proposed spherical robot.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.1 s.173
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• pp.118-123
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• 2000

Most quadruped walking robots under current research are individually controlling every joint ic make them step or walk according to an integrated strategy. Such methods are characterized by at least one pair of an actuator and a sensor installed per each 'oint so that the robots weigh execssively and move inefficiently in terms of energy expenditure. In addition, the task of controlling all the joints simultaneously is quite complex and prone to destabilize the robot motion. These respects keep the existing walking robots away from realistic applications such as transportation even if they have potentially, outstanding adaptability to swamps or uneven terrains as opposed to wheeled vehicles. So, this paper presents a new conceptual quadruped robot developed to walk and steer only with a minimal number of actuators owing to a closed-chain mechanism. To prove its actual performance including the adaptability to various types of terrains. experiments are done with the mammal-type prototype. And. it is also shown that the same concept can be easily extended to carry out different gait forms. for instance, that of spiders only with minor modifications.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.5
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• pp.84-89
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• 2001

The alignment of the rollers carrying the web is found to be one of important factors to the lateral behavior of the moving web and to the quality of the final web products. But, the perfect alignment of the rollers is not always possible and the web itself can be cambered. Thus the control of lateral behavior of the moving web is critical in the most of web handling systems. The web guiding system that adjusts the angle of the alignment between two adjacent rollers is commonly used in industry. But, in this paper a new web guiding system is proposed by using the lateral dynamics of the moving web induced by a tilted roller in normal direction of a web. The computer simulation study was carried out to verify the steering performance of the suggested guiding system. Computer simulation study shows that the performance of the new guiding mechanism is better than that of an existing guiding mechanism.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1300-1305
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• 2009

The various electromagnetic based actuation(EMA) methods have been proposed for actuating microrobot. The advantage of EMA is that it can provide wireless driving to microrobot. In this reason a lot of researchers have been focusing on the EMA driven microrobot. This paper proposed a swimming microrobot driven by external alternating magnet field which is generated by two pairs of Helmholtz coils. The microrobot has a fish-like shape and consists of a buoyant robot body, a permanent magnet, and a fin. The fin is directly linked to the permanent magnet and the magnet is swung by the alternating magnet field, which makes the propulsion and steering power of the robot. In this paper, firstly, we designed the locomotive mechanism of the microrobot boy EMA. Secondly, we set up the control system. Finally, we demonstrated the swimming robot and evaluated the performance of the microrobot by the experiments.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.1
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• pp.87-93
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• 2014

Conventional two-wheeled balancing robots are limited in terms of turning speed because they lack the lateral motion to compensate for the centrifugal force needed to stop rollover. In order to improve lateral stability, this paper suggests a two-wheeled balancing mobile platform equipped with a tilting mechanism to generate roll motions. In terms of static force analysis, it is shown that the two-body sliding type tilting method is more suitable for small-size mobile robots than the single-body type. For the mathematical modeling, the tilting-balancing platform is assumed as a 3D inverted pendulum and the four-degrees-of-freedom equation of motion is derived. In the velocity/posture control loop, the desired tilting angle is naturally determined according to the changes of forward velocity and steering yaw rate. The efficiency of the developed tilting type balancing mobile platform is validated through experimental results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.369-374
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• 2007

This paper presents yaw vibration control performances of railway vehicle featuring controllable magnetorheological damper. A cylindrical type of MR damper is devised and its damping force is evaluated by considering fluid resistance and MR effect. Design parameters are determined to achieve desired damping force level. The MR damper model is then incorporated with the governing equations of motion of the railway vehicle which includes vehicle body, bogie and wheel-set. Subsequently, computer simulation of vibration control via proportional-integral-derivative (PID) controller is performed using Matlab. Various control performances are demonstrated under external excitation by creep force between wheel and rail.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.10
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• pp.132-140
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• 2000

In conventional drilling, burr geometry can be changed according to the variation of drill geometry like point angle, rake angle. Step drilling is proposed to minimize the burr formation in drilling operation. The burr formed in first cutting can be removed in second cutting by the edge in step. The burr formed in second cutting by the edge in step can be minimized according to the change of geometry like, step angle and depth. The mechanism in step drilling is analyzed. Some step drills are applied to drilling the input shaft which is used for vehicle steering. To measure the burr formed in drilling, laser and height gage are used.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.855-857
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• 2007

In recent years, Wireless Mesh Network (WMN) is a compelling topic to many network researchers due to its low cost in deployment, ease and simplicity in installation and scalability and robustness in operation. In WMN, Gateway nodes (Access Point-AP) are in charge of steering the traffic from the external network (e.g. Internet...) to client devices or mesh clients. The limited bandwidth of wireless links between Gateways and intermediate mesh routers makes the Gateways becomes the bottleneck of the mesh network in both uplink stream and downlink stream. In this paper, we propose a mechanism to permit Gateways collaboratively work to manipulate the traffic to fit our network. They will move the traffic from congested links to the unused capacity on other links.