• Proceedings of the KSR Conference
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• 2011.10a
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• pp.365-373
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• 2011

In general, when train drives boost and traction mode, force of delivering to the track was difference between boost and traction driving mode. But, in korea, we've never performed that measure the track wheel load and lateral force while boost and traction driving. This study measured wheel load and lateral force using combination of 7200type locomotive and six freight car. And the train used single and automatic brake. The train drives boost and traction mode. In order to the difference radius of curve, we had measured at 3 point in the curve of turnout.

• International Journal of Railway
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• v.5 no.2
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• pp.93-101
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• 2012

Owing to the lightening of railway vehicles and increased operation speeds, the reduction of running safety in the presence of crosswind is becoming an important problem. In particular, the running safety tends to decrease when vehicles run on curved track. When a crosswind acts on a vehicle negotiating a curve from the outer side, flange climbing can occur. In this study, a full-vehicle model was constructed using the multi-body simulation software SIMPACK, and a simulation of a bogie vehicle with two-axle trucks negotiating a curve was carried out to examine the running safety under the condition where a crosswind acts on the vehicle from the outer side of the curve. As a result, it was verified that the derailment coefficient of the first wheelset becomes large in the exit transition curve and the coefficient of the third wheelset does in the entrance transition curve, and this trend becomes pronounced at low operation speeds in the presence of a stronger crosswind. It was also shown that the critical derailment coefficients obtained by modified Nadal's formula considering the effect of attack angle become close to the actual derailment coefficients at the timing that flange climbing occurs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1611-1619
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• 2015

This study examined the toughness improvement of a track shoe used as the undercarriage of excavator and bulldozer parts. The excavator is operated under poor conditions, such as the build-up field and quarry. Therefore, the track shoe requires high strength and impact toughness to endure immense shock while at work. The track shoe was made of heat treated boron steel. The sufficient possibility of hardenability with the theoretical Jominy curve for boron steel was confirmed while quenching. The Taguchi orthogonal array experiment method was used to optimize the process variables, such as area reduction ratio and heat treatment conditions (tempering temperature and holding time), to achieve toughness improvement. The toughness of the track shoe increased with increasing area reduction, and a tempering temperature of $210^{\circ}C$ and a tempering time of 80 min are beneficial for improving the toughness of the track shoe.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.299-307
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• 2005

The 180 km/h Korean Tilting Train(TTX) which is now developing as a part of the Korean National R&D project, was elaborately designed. As the tilting trains run curve track with the $30\%$ higher speed than normal trains, the higher centrifugal and dynamic force are expected. Furthermore the complex tilting system increase the probability of failure. Therefore it is very important for tilting train to ensure safety against derailment under the various kind of failed condition in the middle of running as well as normal operating condition. The TTX train have the relatively high roll stiffness to improve the lateral ride comfort and to limit the roll displacement on the curve. But the higher roll stiffness increase the risk of derailment on the twisted track. This paper describes the study to review the safety against derailment caused by the wheel unloading on the severely twisted track. The worst combination of maximum cant change with maximum twist defect was established by numerical simulation. And also it was assumed that the air bag deflated and still the train run its speed limit. Those kind of assumption might be the worst case from the view point of wheel unloading derailment on the twisted track. The dynamic simulation was done by means of VAMPIRE S/W and non-linear transient analysis. We found that derailment quotients Q/P was only slightly influenced by track twist but the wheel unloading was greatly influenced. And we ascertained that the higher roll stiffness the higher wheel unloading. In case of air bag deflated situation, the wheel unloading reached up to $100\%$ which means the wheel lift or jumped. Therefore it was concluded that the design need to be improved to ensure the safety against derailment on the maximum twisted track in case of air bag deflated and tilting train's speed limit.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.578-585
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• 2015

Track elastic components can be technically and economically efficient when integrated well into track superstructure of a railway network. In such cases, the elastic rail pad is larger than a 800m radius curve provides smooth rail branching and allows for high-speed operation ($V{\geq}160km/h$). High track resistance causes the tamping intervals to stand out because the constantly increasing share of the sleeper pad further extends the increase of the tamping interval and the long grinding period; the engineering and construction of the small curve radius track provides some measures for reducing the solid sounds. Installation of elastic mats under the ballast can have a good effect, particularly in the context of protection against dust during construction or extensive renovation measures when laying new lines. However, such a process requires special attention and proper installation.

• Steel and Composite Structures
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• v.31 no.5
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• pp.437-452
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• 2019

In this study, in-situ static and dynamic tests of four pre-stressed concrete (PC) track beams with different span lengths and curvatures in a straddle monorail transit system were reported. In the static load tests, the strain and deflection at critical sections of the PC track beams were measured to determine the load bearing capacity and stiffness. The dynamic responses of strain, deflection, acceleration, and displacement at key positions of the PC track beams were measured under different train speeds and train loads to systematically study the dynamic behaviors of the PC track beams. A three-dimensional finite element model of the track beam-vehicle coupled vibration system was established to help understand the dynamic behavior of the system, and the model was verified using the test results. The research results show that the curvature, span length, train speed, and train loads have significant influence on the dynamic responses of the PC track beams. The dynamic performance of the PC track beams in the curve section is susceptible to dynamic loads. Appropriate train loads can effectively reduce the impact of the train on the PC track beam. The PC track beams allow good riding comfort.

• Journal of the Korean Society of Safety
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• v.31 no.3
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• pp.130-135
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• 2016

It is very hard to analyze the train derailment safety quantitatively at the curved section because of the diversified affect parameters including the complex interaction between wheel and rail, the train conditions such as the shape of wheel, suspension system, the track conditions such as the radius of curve, cant, transition curve, and the operation conditions, etc. Two major factors related to the running safety of railway vehicle are classified as the railway vehicle and the track condition. In this study, when the railway vehicle passing through curves of actual track condition of subway line NO.3 in seoul ($Yeonsinnae{\leftrightarrow}Gupabal$), the effect that has influence on running safety depending on rail inclination. The analysis result of 1/40 rail inclination condition is more favorable on running safety than other rail inclination conditions because derailment coefficient and wheel unloading ratio are the lowest.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.1187-1190
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• 2009

CURVE SQUEAL NOISE IS THE INTENSE HIGH FREQUENCY TONAL THAT CAN OCCUR WHEN A RAILWAY VEHICLE TRAVERSES A CURVE OR A SWITCH. THE HIGH NOISE LEVEL CAUSES ANNOYANCE FOR PEOPLE WHO LIVE IN THE NEIGHBOURHOOD OF THE SQUEALING RAILWAY TRACK AS WELL AS FOR THE PASSENGERS IN CARS WITH CURVES. THIS PAPER EXAMINES THE SPECTRAL SOUND DISTRIBUTION IN CURVES FOR KTX TRAIN. THE FREQUENCY RANGE IS FROM AROUND 4,000 TO ALMOST 16,000Hz, WITH NOISE LEVELS UP TO 92dB IN CURVE R400.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.379-386
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• 2007

Recently the concrete slab tracks are being constructed on roadbed in the Kyong-bu 2nd stage high speed railways. In responding to this trend, new design standards and track materials maintenance systems, based on the slab track material safety and usage perspective, are needed. This research provides the design standards and the maintenance system. The proposed standards and the maintenance system are based on the track theory and the track-train interaction program developed, where the roadbed displacement and train speed are utilized as mediating variables. In the analysis, the dynamic response of track-train interaction apply to various speeds and displacements. the roadbed displacement is shown in a sine curve, the scope of the displacement occurrence, presented in its wavelenths, include 6meters, 10meters, 15meters, 20meters, 30meters. the train speeds involved are 50,100, 150,200,250,300,350,400 kilometers per hour.

• Korean Journal of Applied Biomechanics
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• v.23 no.2
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• pp.109-116
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• 2013

The purpose of this study was to provide fundamental information for the enhancement of performance through kinematic analysis of cornering according to the radius of curve course in short track speed skating. To perform this study, six skaters: three narrow radius players(N, body mass: $56.0{\pm}7.2$ kg, height: $163.7{\pm}5.1$ cm, age: $21.3{\pm}1.5$ yrs) and three wide radius players(W, body mass: $61.0{\pm}9.5$ kg, height: $169.0{\pm}4.4$ cm, age: $20.0{\pm}1.7$ yrs). Three-dimensional motion analysis was performed on the section from the forth block starting to show the change of radius to the sixth block using eight infrared cameras(sampling frequency of 100 Hz for N and W players). The time of push-off was greater for N than for W(p<.05) while the radius of center of mass was greater for W than for N(p<.05). The flexion and extension of knee and hip joint were greater for N than for W(p<.05). The external rotation of left knee joint was greater for N than for W(p<.05). Based on the findings, a small radius by increasing the range of the flexion and extension of knee and hip joint with greater external rotation of left knee joint would be related to more efficient run at curve. It is expected that these results will be useful in developing a training program for enhancing performance of short track speed skating athletes.