• Journal of Biomedical Engineering Research
• /
• v.18 no.4
• /
• pp.447-456
• /
• 1997

When the disabled is operating a rehabilitation assisting system with a joystick by himself, unlike in the case of a normal person, tremor with joystick control or instant miscontrol can often occur. If these misoperations should be directly relayed to the system, shaking or malfunction of the mobile rehabilitation assisting system might be the result. The safety of the disabled is of prime concern. To solve this problem, that is, to prevent the miscontrol of the disabled operator and avoid crashes into his or her surroundings, we propose the force-reflection locomotion algorithm with the joystick. This method uses ultrasonic sensors to measure the distance between the object and mobile robot. Based on the reception of sensory data, the necessary torque is applied via the joystick to the attatched motor. To confirm the effectiveness of the proposed method, the subjects on the reflected force by the dynamic characteristics of the joystick and the reflected force by the distance information are tested Even though there are some differences in human dexterity, we confirmed the fact that the information from the obstacles was relayed to the operator via the joystick and resulted in an improved operational performance and safety level with regard to those obstacles.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.34 no.7
• /
• pp.943-946
• /
• 2010

In this study, a front suspension system, which is mounted on the handle itself, was suggested because of its light weight and cost efficiency. The shock absorption was evaluated for the three types of suspension models; non-suspension, suspension on front forks (existing model), and suspension on handle (suggested model). The human body model was used for performing impact simulation for comparing the shock absorption for the suspension models. The result of the simulation shows that shock absorption for the proposed suspension model was not as good as that for the front fork suspension model. Nevertheless, the shock absorption observed for the proposed suspension model was significant when compared to the non-suspension model. Consequently, the proposed suspension model could be applied to lightweight bicycles.

• Journal of Korea Multimedia Society
• /
• v.12 no.4
• /
• pp.600-607
• /
• 2009

In order to obtain continuous navigation information at low cost, we demonstrate, in this work, a position system which is constructed by integrating accelerometers with GPS. The proposed system eliminates vibration and noise elements of accelerometers by using Kalman filter. Calculating continuous navigation information is executed by unifying GPS position data and accelerations of moving and centripetal directions which affect the vehicle. Through simulations and experiments, we show that the performance of GPS can be improved by employing accelerometers. Our proposed system can provide stable and seamless position information where the GPS signal is unavailable due to obstruction like tunnels, and high buildings. The designed system can be implemented at low cost of circuit design and production, and satisfy various installation conditions.

• Proceedings of the KSR Conference
• /
• 2000.05a
• /
• pp.479-486
• /
• 2000

There has been recently an on-going effort in railway community to improve the dynamic performance of on-site railroad track with limited track possession time. In this paper, train running test lateral resistant force test and static/dynamic analyses are conducted before and after sprinkle of the ballast stabilizer in order to investigate the dynamic behaviors and parameters of the railroad track. Based upon the above results, effects of the stabilizer is verified, and a table for the track modulus representing on-site track condition and the methods to reduce the vibration and the transmitting forces of the ballasted track components to the infrastructures are suggested. It is thought that the suggestions made in this paper could be used as the preliminary data for the condition assessment and the maintenance of the track in the future.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.2
• /
• pp.255-260
• /
• 2021

The importance of electric vehicles is gradually increasing due to the recent depletion of fossil fuels. In order to use an electric vehicle, the battery built into the vehicle must be frequently charged. Electric vehicles has very good performance in terms of noise and vibration. However, due to the limitations of the battery, the mileage is considerably shorter than that of an internal combustion engine vehicle once it is charged, and the battery charging time is relatively long compared to the refueling time. There are two types of charging methods for electric vehicle batteries: plug-in and wireless charging. In this paper, we introduced the wireless charging technology for electric vehicles and the current state of technology development and standards in major countries.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.4
• /
• pp.464-469
• /
• 2019

Tapered roller bearings are used widely in vans, trucks, and trains because they can support the vehicle in a stable manner even under a heavy load. The cage of a tapered roller bearing maintains the gap between the rollers, which prevents friction wear and suppresses heating. If the cage is severely deformed due to resonance, the roller may not be able to roll smoothly and even leave the cage. Consequently, it is very important to analyze the dynamic characteristics of the cage for reliable performance of a bearing. The cage essentially has geometrical tolerance in the manufacturing process. In this paper, the effects of those geometrical imperfections on the dynamic characteristics of the cage were investigated. As a result, natural frequency separation occurred near the natural frequency of the ideal cage due to geometrical imperfections. In addition, the interval was proportional to the magnitude of the geometric error, and the interval increased with increasing mode number.

• Journal of the Korea Society of Computer and Information
• /
• v.28 no.10
• /
• pp.1-8
• /
• 2023

If there is a defect in the wheel bearing, which is a major part of the car, it can cause problems such as traffic accidents. In order to solve this problem, big data is collected and monitoring is conducted to provide early information on the presence or absence of wheel bearing failure and type of failure through predictive diagnosis and management technology. System development is needed. In this paper, to implement such an intelligent wheel hub bearing maintenance system, we develop an embedded system equipped with sensors for monitoring reliability and soundness and algorithms for predictive diagnosis. The algorithm used acquires vibration signals from acceleration sensors installed in wheel bearings and can predict and diagnose failures through big data technology through signal processing techniques, fault frequency analysis, and health characteristic parameter definition. The implemented algorithm applies a stable signal extraction algorithm that can minimize vibration frequency components and maximize vibration components occurring in wheel bearings. In noise removal using a filter, an artificial intelligence-based soundness extraction algorithm is applied, and FFT is applied. The fault frequency was analyzed and the fault was diagnosed by extracting fault characteristic factors. The performance target of this system was over 12,800 ODR, and the target was met through test results.

• Journal of the Korea Society of Computer and Information
• /
• v.29 no.4
• /
• pp.115-123
• /
• 2024

In this paper, we propose a vibration notification system that combines navigation information and wearable bands to ensure safe driving for the transportation vulnerable. This system transmits navigation driving information to a linked application, converts it into a vibration signal, and provides notifications through a wearable band. Existing navigation systems focus on providing route guidance and location information, so the driver's concentration is dispersed, and safety and convenience are deteriorated, especially for those with mobility impairments, due to standard vision and delayed recognition of stimuli, resulting in an increasingly high traffic accident rate. To solve this problem, navigation driving information is converted into vibration signals through a linked application, and vibration notifications for events, left turns, right turns, and speeding are provided through a wearable band to ensure driver safety and convenience. In the future, we will use cameras and vehicle sensors to increase awareness of safety inside and outside the vehicle by adding a function that provides notifications with vibration and LED when the vehicle approaches or recognizes an object, and we will continue to conduct research to build a safer driving environment. plan.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.9
• /
• pp.493-501
• /
• 2016

In this study, core technologies of a traction system on a mountain tram operating on the track of mountain road full of sharp curves and steep gradients were developed. In domestic mountain resort areas, sometimes the transportation service is not provided in winter because of ice and heavy snow on roads, so a mountain railway service independent of the climate and geographic conditions is needed. A traction system was designed taking into account of the power of a traction motor to climb the gradient of 120 ‰, which is common in domestic mountainous areas. and power transmission system was designed to consider the installation space for the traction system. In addition, a reduction gear and a propeller shaft were developed. An elastic pinion was developed and applied to the rack & pinion bogie system for steep gradient so that noise and vibration generated by contact between the steel gears could be reduced. Impact comparison tests showed that the vibration level of the elastic pinion is one-third lower than that of previous steel pinion. Independent rotating wheels and axles were developed for the bogie system to operate on the sharp curve of a 10 meter radius. In addition, the band braking system was developed to enhance the braking force during running on the steep gradient. A test for the braking force showed it exerts the required braking force. The performance of the developed core components were verified by the tests and finally they were applied to the bogie system running on the track of steep gradient and sharp curve.

• Journal of the Korea Society for Simulation
• /
• v.15 no.4
• /
• pp.119-128
• /
• 2006

A turnout system which permits trains to pass from one track to another is a combination of the switch, the crossing, lead rails which are necessary to connect the switch and the crossing, two guard rails and a switch machine for operating the switch. A turnout is the sole moving part among the railway components and has complex configuration, so the safety has always been raised an issue. In Korea, it is planned to adopt the high speed tilting train, which operates at the maximum speed of 200km/h, at conventional lines by the year of 2010. However, for the application of the tilting train to conventional lines, it is prerequisite to establish a stable turnout system allowing the tilting train to pass through it without reducing speed. Therefore, the improved turnout system for the speed-up of conventional lines has been developed and the prototype of the turnout system has been constructed. In this study, simulation of noise and vibration around the improved turnout system was performed in order to predict the generation level of noise and vibration due to passing of the tilting train through the turnout system.