• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.4
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• pp.538-549
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• 2021

In this study, a trim tab on the stern hull of a small high-speed vessel of approximately 10 m length sailing at a Froude number of 1.0 was designed for energy efficiency. The running attitude and resistance performance of the bare hull and trim tab hull at several angles to the base line were analyzed for model and full scale ships using computational fluid dynamics, and compared to investigate the scale effect. The analysis results for the bare hull were quite similar, but a difference in the attitude control under same conditions of the trim tab was observed, resulting in the total resistance error. However, there was no significant difference in tendency of the variation in the resistance with the attitude. Thus, the optimum running attitude could be determined from the tendency despite the scale effect, but a full scale analysis is required to analyze the control of the attitude by the trim tab and flow characteristics near the full scale ship.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.220-224
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• 2002

As the train run through the tunnels, especially at high speed, pressure shock developed by the running train gives the influence on the pressure fluctuation inside the tunnel and consequently, inside the car. This pressure changes and pressure gradient is closely related with the tunnel section, train speed, air tightness of the train, length of the tunnel, etc. This study includes the analysis of the pressure behavior at the varied train speed and tunnel length. The results show that train speed affects the pressure gradient inside the car almost linearly, and that there exist the critical tunnel lengths that gives the maximum value of pressure change and pressure gradient, respectively.

• Proceedings of the KSR Conference
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• 1999.11a
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• pp.376-384
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• 1999

In this paper, we introduce the on-line test plan of high speed rail development, which will be carried out at the test section of Seoul-Pusan high speed line from May to October, 2002. The test items are decided focused on the verification of the perofrmace and acquirement of the technical data of the high speed rail system development. The running time and distance of the train are calculated for several limited maximum speed cases. The detailed test scenario shall be developed according to the process of development and design of the system.

• Journal of Korean Physical Therapy Science
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• v.11 no.4
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• pp.29-37
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• 2004

Measurements of plantar pressure provide an indication of foot and ankle function during gait and other functional activities because the foot and ankle provide necessary support and flexibility for weight bearing and weight shifting while people are performing these activities. Plantar pressure is being increasingly used in both research and clinical practice to measure the effects of various footwear and physical therapy intervention. The influence of walking speed and ground inclination on plantar pressure parameters However has not been evaluated in detail. So, in this study to determine the effect of changes in walking speed and ground inclination on plantar pressure treadmills with different walking speeds and inclination were used. Plantar pressure parameters were measured with the Parotec system using the walking and running in 20 healthy participants(10 male, 10 female) aged $20{\sim}28$(mean 22.22, S.D.2.26 years) when slow walking and running. The result of this study with increased die walking speed, the peak pressure of 1st, 5th metatarsal head and total contact time and impulse total at the forefoot was affected by walking speed; however, die peak pressure, contact time and impulse total at the forefoot was not affected by ground inclination.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.529-544
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• 2007

After rapid running is begun in domestic, problem by the train gust that was not considered at existent train running appeared. If the High-Speed railway business speed rises by 350km/h in the future, is going to become more big problem. This study conducts an experiment that measure in local about KTX train beside Gyeong-Bu High speed railroad track about aerodynamics effect that happen by passage of train and analyzed. In case KTX II runs with the 350km/h speed, forecasted effect that get in the simple vertical surfaces parallel to tracks according to distance from rail center. Compared construction size with structural analysis in case do not consider with case that consider the train gust about sound proof walls representatively. As a result, proposed wind load standard that apply at sound proof walls design.

• Steel and Composite Structures
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• v.32 no.4
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• pp.467-478
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• 2019

Running safety and ride comfort of high speed railway largely depend on the track geometry that is dependent on the bridge deformation. This study presents a theoretical study on mapping the bridge vertical deformations to the change of track geometry. Analytical formulae are derived through the theoretical analysis to quantify the track geometry change, and validated against the finite element analysis and experimental data. Based on the theoretical formulae, parametric studies are conducted to evaluate the effects of key parameters on the track geometry of a high speed railway. The results show that the derived formulae provide reasonable prediction of the track geometry change under various bridge vertical deformations. The rail deflection increases with the magnitude of bridge pier settlement and vertical girder fault. Increasing the stiffness of the fasteners or mortar layer tends to cause a steep rail deformation curve, which is undesired for the running safety and ride comfort of high-speed railway.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.356-362
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• 2011

Usually urban railways are built under ground thus the necessary condition of urban railroad, a linear-shaped track, causes a difficulty in enhancement of speed limits of urban rail. Also the underground construction of city railroad produces speed limit values reduced according to a speed code array, in case of speed decision according to the conventional block section division, thus onventionally it could not but apply speed limit values lower than actual safety speeds. In this study, The above two facts induced the author to study on a method to enhance speed limit values for CBTC within existing urban railroad sectors. Since it is possible to exchange data continuously and to control speeds in case of railroads based on CBTC, the author applied result values of speed limits, which were gained based on a railroad condition, a linear track, to the CBTC system without correction of the result values and then the author compared and analyzed, through simulation, the running times and the efficiencies of running energies between railway stations, between the existing fixed-block system and the CBTC system. As a result simulation, the improvement of speed and the deceleration distance of reduction confirmed that it was effective to reduce the time to travel between stations. A fixed block the set of constraints on the speed limit, he way the operation is optimized based CBTC speed limit by suggesting ways to reset the scheduled speed measures to improve were extracted.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.81-87
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• 2017

This paper describes the dynamic behavior and enhancement of Korean high-speed trains. The tail vibration reduction method of the yaw damper installation method change, which was derived from previous research, was applied to the running test of high-speed train. In addition, the vibration reduction method for the entire vehicle was derived by a numerical method and its effect was confirmed by a running test. The improved design was applied to the double-deck high-speed train coaches and the commissioning proceeded without problems in dynamic behavior. Sensitivity analysis of the suspension parameters affecting the critical speed of Korean next-generation high-speed trains was performed and four design variables that greatly affected the critical speed were derived. These were in the order of the primary elastic joint x-directional stiffness, the secondary yaw damper series stiffness, the secondary lateral damper damping coefficient, and the carbody damper damping coefficient. By optimizing the design variables, the suspension parameter that improves the critical speed by 23.3% can be used in the commercial designs of Korean next-generation high-speed trains.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2005.11a
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• pp.250-255
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• 2005

In this paper, we propose a new fast running FIR filter structure that improves the convergence speed of adaptive signal processing and reduces the computational complexity. The proposed filter is applied to wavelet based adaptive algorithm. Actually we compared the performance of the proposed algorithm with other algorithm using computer simulation of adaptive noise canceler based on synthesis speech. As the result, the frequency domain algorithm is prefer than the existent time domain. we analyzed the Wavelet algorithm, short-length fast running FIR algorithm, fast-short-length fast running FIR algorithm and proposed algorithm.

• Korean Journal of Applied Biomechanics
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• v.17 no.2
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• pp.61-73
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• 2007

The purpose of this study was to investigate the influence of the muscular endurance on the kinematic factors during a prolonged run. Subjects, 12 males, who were divided into three groups(lower group, general group, and in higher group) after measuring the lower limb's muscular endurance previously. They were asked toe run on the treadmill at 7.4km/h of speed. To analyze the kinematics parameters of the trunk during running, the ProReflex MCU Camera(Qualisys, Sweden) were used. All parameters were sampled from 5 minute, 40 minute, and 60 minute moments during running. An ANOVA with Repeated Measure was used to test the statistic significance between and within groups for all parameters determined with SPSS 11.0. Significance was defined as p<.05. The conclusions were as follows; There was significantly difference within(lapse of running time) groups in the take-off and minimum knee angle event of swing phase of the trunk flexion and extension. In conclusion, the muscular endurance affected on movement of the trunk during a prolonged run. In addition, it showed that there was significant difference in the energy consumption by lapse of running time. Therefore, it seems to be relationships between the muscular endurance and running efficiency.