• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2860-2865
• /
• 2011

Recently, the number of passengers using urban railway has been increased by reasons of the reductions of car use due to high fuel prices and the enlightenment about the environment. Above all, the noise and the vibration coming from the friction between the wheel and the rail of trains in operation which is not only a factor that hinders riding comforts but causes civil complaints. Furthermore, the noise has become social issues from tightening the relevant regulations by the government since January 2010. Although ballasted tracks were constructed on urban railways at the time of opening, they have been changed into slab tracks because slab tracks require much less maintenance. However, in view of sound absorptivity of track, slab tracks have 10 times less capability than ballasted tracks(ballasted track : 0.5~0.6/slab tracks : 0.06) results more noise than that of ballasted tracks as much as 3dB(A) since slab tracks emit more reflection noise. Therefore, in order to minimize reflection noise on slab tracks, noise abatement system has been developed as a national R&D program to apply on-site test. It is assumed that the construction technology developed in this study can be used not only as basic data for the on-site test for the noise reduction in urban railway but as an efficient construction method.

• 제어로봇시스템학회:학술대회논문집
• /
• 2004.08a
• /
• pp.1491-1495
• /
• 2004

For the evaluation of the mobile robot performance in complex environments, the experimental approach in an actual physical environment has been commonly taken. In the physical experimental approach, however, it is quite difficult to define the proper environment for the evaluation due to the lack of commonly agreed characteristics of the test environment. Particularly the number of combinations of types and physical parameters of the obstacles that the mobile robot is expected to deal with is practically unlimited. In an effort to simplify and improve the effectiveness of the evaluation process, we propose an evaluation method using decomposed environmental elements, where we evaluated the performance of the robot for a small group of simple and decomposed obstacle components, for examples projection and slope, instead of a large group of complicated random obstacles. The paper describes a set of simple obstacle models and performance parameters that we have chosen for the effective evaluation process. As an alternative to the physical experimental evaluation approach, in this paper, we used a virtual evaluation environment where the robot and the physical test environment has been modeled using a commercial multi-body dynamics analysis packaged called RecurDyn.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.25 no.9
• /
• pp.1-7
• /
• 2011

A performance delivers the contents and feeling through human bodies and stage settings in the limited space of a stage. Among the stage settings, the lighting creates overall atmospheres effectively according to the situations of the performance such as a time flow, a change of seasons, an expression of the mental state of the performer. As the LED lighting is used more widely, the number and the size of the lighting is being decreased, which makes it possible for various devices to be used. However, just as conventional lighting devices, most of them are fixed. So it is difficult to use them at a blind spot and to replace them. To solve this problem, this article suggests a system which replaces lighting automatically and moves. As it can moved to a spot we want on a rail, and the lighting system can be replaced by itself, it can have various lighting effects, increasing the effectiveness of the performance. Additionally, it can also decrease the danger of a worker operating the lighting device located at a high place. At the mock-up experiment, its mobility and stability on a rail were tested using the wheel of the Modular Robot.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.10
• /
• pp.1924-1934
• /
• 2011

This paper is concerned with the robustness evaluations of the guidance controller for a bimodal tram which is being developed by the Korea Railroad Research Institute (KRRI). The bimodal tram is an all-wheel steered multiple-articulated vehicle as a new kind of transportation vehicle. This vehicle has to be equipped with an automatic guidance system. In [1], such a controller has been recently proposed. However, since the performance is affected by weight change of the vehicle due to number of the passenger, model parameter uncertainties depending on the state of friction and the elasticity of the tire, and a typhoon, the controller designed must be examined with these conditions. As expected, because the vehicle dynamics is highly nonlinear, for the sake of investigating the robustness of the controller we compose two simulation ways based on the vehicle models which are implemented by the ADAMS and the MATLAB/LabVIEW toolboxes. Different uncertainties and a typhoon disturbance have been considered for the simulation conditions. Simulation results are shown.

• Journal of the Korean Society for Advanced Composite Structures
• /
• v.4 no.4
• /
• pp.22-29
• /
• 2013

Accumulation of more than 20,000,000 vehicles since the establishment of the quality of life and economic development needs several parking lots and cause crack problem in Korea. Related structures in large cities due to the lack of parking garage attached to secure underground parking structures are actively being built, and the basement parking lot will continue to increase more stories and the trend is expected to be larger. But so far, construction of the underground parking structure is related to a number of problems, including cracks in the structure. Therefore, in this study, repair, reinforcement and a few non-economic losses in the current design criteria are presented. The review of the structure used to current design criteria is to minimize crack and maximize usability.

• Journal of Yeungnam Medical Science
• /
• v.30 no.2
• /
• pp.112-115
• /
• 2013

The incidence and importance of tricuspid valve regurgitation after a blunt chest injury has risen with the increase in the number of automobile accidents and steering wheel traumas. This kind of injury has been reported more frequently in the last decade because of the better diagnostic procedures and understanding of the pathology. However, tricuspid valve regurgitation following a blunt chest injury can still be easily missed because most patients do not show symptoms at the time of the trauma. A 55-year-old male patient presented himself at our facility after suffering a chest injury from an automobile accident. His transthoracic echocardiography (TTE) revealed severe tricuspid valve regurgitation due to the prolapse of his anterior valve leaflet. We report a case of asymptomatic tricuspid regurgitation that developed after a blunt chest injury.

• Bulletin of the Korean Space Science Society
• /
• 2003.10a
• /
• pp.26-26
• /
• 2003

During fabrication process for the large space optical surfaces, the traditional bound abrasive grinding with bronze bond cupped diamond wheel tools leaves the machine marks and the subsurface damage to be removed by subsequent loose abrasive lapping. We explored a new grinding technique for efficient quantitative control of precision CNC grinding for space optics materials such as Zerodur. The facility used is a NANOFORM-600 diamond turning machine with a custom grinding module and a range of resin bond diamond tools. The machining parameters such as grit number, tool rotation speed, work-piece rotation speed, depth of cut and feed rate were altered while grinding the work-piece surfaces of 20-100 mm in diameter. The input grinding variables and the resulting surface quality data were used to build grinding prediction models using empirical and multi-variable regression analysis methods. The effectiveness of the grinding prediction model was then examined by running a series of precision CNC grinding operation with a set of controlled input variables and predicted output surface quality indicators. The experiment details, the results and implications are presented.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2015.05a
• /
• pp.346-349
• /
• 2015

Generally, in order to verify the degree of tire wear or abnormal wear, a driver or an auto mechanic checks the degree of tire wear and the existence of tire abnormality, directly with the naked eye or by way of using a gauge equipment. In case of such verification, individual subjective judgments may be involved or a driver may suffer heavy burdens to expend the time and cost for using the wheel alignment equipment. Therefore, this thesis will use a number of laser sensors to check the existence of abnormal wear and the degree of wear on each tire and develop a system checking the sides of tires to receive the tire information, so that subjective judgments may be overcome and objective and accurate judgments may be rendered.

• Journal of the Korean Home Economics Association
• /
• v.45 no.4
• /
• pp.53-59
• /
• 2007

We need to diversify the colors by natural dyeing for promotion and extention of the natural dyes market, because natural dyestuffs have the limitation the number of the colors to express, compare to synthetic dyestuffs. It was investigated that wool and silk fabrics could be dyed to green colors using natural mugwort and indigo as one of color diversification, in order to express green color that is difficult to be shown by natural dyeing. The mugwort dyebath was prepared to concentration of $25{\sim}100g/l$ using dried mugwort plant and indigo dyebath was prepared to concentration of $5{\sim}20g/l$ using natural indigo powder. Wool fabrics and silk fabrics were dyed to green(GY, G, BG in Munsell color wheel) by two batch methods using the mugwort and indigo dyebaths. the mugwort dyeing was applied at $80^{\circ}C$ for 20minutes and indigo dyeing applied for $5{\sim}7$ minutes in room temperature. The colorfastness to drycleaning and abrasion of the dyed fabrics were shown good as grade 4-5 or 5.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.8 no.6
• /
• pp.591-598
• /
• 1984

The results of measurements showing normal vibrations and rubbing noise generated during unlubricated smooth sliding between metal surfaces are presented. The measurements were made on pin-on-disc type apparatus instrumented with piezoelectric acceleration transducers and microphones. Spectral analysis of the both signals up to frequency of 10kHz indicates that they are closely correlated. The major components of both signals in this frequency range are primarily associated with the normal contact vibrations which are excited by surface irregularities being swept through the contact region during sliding. As an approximation to the seismic input of surface irregularities, an effective surface wavenumber spectrum was assumed in the form of an inverse vibration and noise measurements for a number of surface finishes and mean loads. The predominant frequency component of which levels of the normal vibration and noise are close to overall levels of the both signals is induced by contact resonance between the two bodies and its frequency can be calculated from the Hertzian theory.