• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1622-1627
• /
• 2008

A suspension is a core part, determining running stability and riding quality of vehicles and its stiffness is essential parameters in the process of vehicle designing. Suspension stiffness shall be adjusted to meet requirements of running stability and curve running performance, as adding stiffness to primary suspension for running stability in high-speed running results running performance degradation in curved track. The purpose of the report lies in utilization of usable data for optimization of suspension via analyzing running performance through changing stiffness of railway vehicle suspension.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1628-1633
• /
• 2008

Safety of railroad is result of reliability which is received from test & evaluation of system. Railroad system is consisted of various sub system such as vehicle, supply of electric power, signal, communication, rail track construction, operation. To secure safety of railroad, evaluation about parts, assembly, sub system, whole system etc.. that compose railroad is essential. In this paper, I wish to describe for results that analyze korean tilting vehicle's derailment coefficient developed by national research achievement. Result that evaluation korean tilting vehicle's running safety, verified that secure even if speed-up 30 km/h than operating speed of present in curved line.

• Smart Structures and Systems
• /
• v.23 no.4
• /
• pp.347-357
• /
• 2019

A new methodology for mitigation of the wheel squealing is proposed and investigated based on the dithering control. The idea can be applied in railway lines particularly in urban areas. The idea is clearly presented, and applied to a validated model. A full-scale model including the vehicle, curved track and wheel/rail contact is developed in the time domain to analyze the possibility and level of wheel squeal noise. Comparing the numerical results with a field test, the model is validated in different levels namely i) occurrence, ii) squealing frequency and iii) noise level. Two different approaches are proposed a) dithering of the wheel with piezoelectric patches and b) dithering of the rail with piezoelectric stacks. The noise level as well as the wheel responses is compared after applying the control strategy. A parametric study is carried out and effect of the dithering voltage and frequency on the squealing noise is investigated. It is found that both the strategies perform quite effectively within the saturating threshold of piezoelectric actuators.

• Journal of the Korean Society for Railway
• /
• v.15 no.4
• /
• pp.364-369
• /
• 2012

This paper presents an experimental study on the radio propagation characteristics in subway tunnel at 18GHz frequency band which has been assigned to video transmission between train and wayside. The radio propagation tests are carried out in the subway tunnel of Seoul Metro using the antenna and communication devices of the prototype video transmission system. The measurement results show that 18GHz radio propagation in subway tunnel has smaller path loss than that of general outdoor radio environment. It is also cleared that the arch-type tunnels have smaller radio propagation losses than rectangular tunnels, and single track tunnels have smaller pass loss than double track tunnels. From the measurements, the radio propagation coverage is worked out as 520 meters. The curved tunnels which cannot have LOS communication between transmitter and receiver have large pass losses and fluctuation profile along distance. The radio propagation coverage along curved tunnels is worked out as 300 meters. These investigation results can be used to design the 18GHz radio transmission system for subway tunnel by providing the optimized wayside transmitter locations and handover algorithm customized to the radio propagation characteristics in subway tunnels.

• Journal of the Korean Society for Railway
• /
• v.18 no.5
• /
• pp.457-465
• /
• 2015

A method of evaluating the optimal alignment range while considering ride comfort when performing line renewal of curved tracks for speed-up is proposed in this study. The proposed method was applied to analyze the optimal renewal range for horizontal alignments with the smallest curve radii in the Kyung-Bu high-speed line; a parametric study on the effects of various initial design conditions on the permissible renewal range and optimal alignment range was also performed. From the analysis results, it was found that the permissible range is enhanced in proportion to the increase in the curve radius and the cant. It was also verified that a slight adjustment of the horizontal alignment enables speed-up even in the case of R7000/R8000, placed in the ballasted track section of the Kyung-Bu high-speed line.

• Journal of the Korean earth science society
• /
• v.35 no.3
• /
• pp.168-179
• /
• 2014

The purpose of this study focuses on the prediction time and location of turning-point of typhoon tracks using the water vapor images of Communication, Ocean and Meteorological Satellite (COMS) which has a very short observation interval. It targets a more accurate prediction of turning-point of typhoon tracks through the relationship between dry slot and northern/southern oscillations of jet stream. Jet stream moves by the position of jet streak and the ${\upsilon}$-component velocity of geostrophic wind. If the ${\upsilon}$-component of geostrophic wind gets stronger toward south, jet stream develops into a circular jet. In that condition, dry slot in satellite water vapor imagery extends toward south, and typhoon track turns as the distance of curved moisture band (CMB) gets narrowed down. If the interval of CMB is below $15^{\circ}$ of latitude, the typhoon track is turning toward north or northeast within 24 hours. As a result, typhoon track showed that when dry slot position was located less than $32^{\circ}N$, typhoon turned its track at $20-23^{\circ}N$ ($1^{th}$ Kong-Rey 2007 and $17^{th}$ Jelawt at 2012), and when in $35^{\circ}N$ above, it turned at $27^{\circ}N$ ($4^{th}$ Man-yi 2007).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.7
• /
• pp.275-282
• /
• 2018

Mountain trams are an environmental-friendly transportation system that run wirelessly on an embedded track constructed on previous mountain roads, and can run despite the frozen road. On the other hand, there is some difficulty on sharp and steep tracks. In this study, after possible technical problems were defined in mountain trams running on a sharp and steep track, the design solutions for the interface structure of bogie and carbody were proposed. In addition, a prototype was made and its performance was tested to verify the solutions. Because the difference in the distance of the inner and outer rails on a sharp curve is severe enough to interrupt running, independent rotating wheels with different angular speeds were developed and applied. To prevent derailment due to the large attack angle and lateral force caused by the previous vehicle of 2bogie-and-1carbody on the sharp curve, a vehicle with 1bogie-and-1carbody was designed and applied. A prototype vehicle of 1bogie-and-1carbody with independent rotating wheels was made to improve the performance during the test running on a small track. A coupler was designed to absorb the large rotations of 3 degrees-of-freedom between the carbodies of a mountain tram running on the steep curved track. After a small scale prototype was made, the performance was verified by a function test.

• Journal of Korean Society of Steel Construction
• /
• v.13 no.2
• /
• pp.211-221
• /
• 2001

The dynamic force estimation and strength design of KALES(Korea Accelerated Loading and Environmental Simulator) are studied. The KALES is continuously rotating the test track and subjected to the dynamic or impact forces during operation since the track is composed of straight and curved line. To estimate the dynamic equation for the model car which was already made is derived with analytical and experimental techniques. Using similarity relationships between the model car and KALES, the dynamic force and stability properties for KALES can be predicted. The stress analysis and fatigue life estimation of KALES is also estimated with the calculated dynamic load. From the stress analysis and fatigue life estimation results, it was found that the design of KALES is safe.

• Journal of the Korean Society for Railway
• /
• v.12 no.5
• /
• pp.700-706
• /
• 2009

Unlike high-speed KTX trains and dual track railways, most single-track railways are not popular among passengers because of long travel hours. As a solution to the problem, tilting trains will be deployed along the conventional line. Tilting train has a mechanism that enables increased speed on regular and curved railway tracks. As a train rounds a curve at speed, objects inside the train experience centrifugal force. This can cause packages to slide about or seated passengers to feel squashed by the outboard armrest due to its centripetal force, and standing passengers to lose their balance. Tilting trains possess a top speed of up to 180 km per hour as opposed to the previous 140 km per hour, so allow the train to pass curve at higher speed without affecting passenger comfort. This paper describes the methodology study to estimate the benefits, especially on the extra benefits in case of tilting actuation.

• Physical Therapy Rehabilitation Science
• /
• v.3 no.1
• /
• pp.55-62
• /
• 2014

Objective: To study the effects of gait training with additional weight and gait training with non-additional weight on balance ability and gait ability in patients with chronic stroke through comparative analysis. Design: Randomized controlled trials. Methods: The subjects were divided randomly into two groups: additional weight group (AWG, n=12), and non-additional weight group (NAWG, n=10). Both groups received general physical therapy for 30 min in 1 session, 5 sessions per week during 6 months. The AWG practiced gait training with additional weight of 0.1 and 0.5 kg for 20 min a day, 3 days per week for 6 months and the NAWG practiced gait training with non-additional weight for 20 min a day, 3 days per week for 6 months. Patients in both groups were instructed to walk as fast as they could along a 35 m long track (straight for 20 m and curved for 15 m). Patients walked with their hemiplegic side on the inside of the track while a physical therapist followed along to instruct patients to maintain a straight posture. Balance ability was tested with the Functional Reach Test, the Timed Up and Go test, and the Berg Balance Scale, and gait ability was tested with GAITRite. The results of balance and gait ability were analyzed before and after interventions. Results: A significant increase in FRT, TUG, BBS was seen in both groups after intervention (p<0.05). A significant increase in gait ability was seen in the AWG after intervention (p<0.05). For balance and gait ability, the results from the AWG was significantly improved compared with the NAWG (p<0.05). Conclusions: Gait training with additional weight improves balance ability and gait ability in stroke patients, this gait training method is effective and suitable for stroke patients to increase the ability of functional performance.