• Proceedings of the KSR Conference
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• 2003.10b
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• pp.477-482
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• 2003

The railway bridges on the new high-speed line are the first structures designed and constructed by our local engineers for high-speed running. In securing running stability and riding comfort in high-speed running, it is very important to verify the performance of structures and local specifications and design criteria by measuring and analyzing the dynamic behavior of main structural members. In this study, 4 different types(simple-span, 2, 3, 4-continuous spans) of PCS Box bridges on the test line(Yongwa$\~$Simok section) were selected, each representing a different type of superstructures, in order to verify the performance of the bridges by measuring dynamic responses during the test-run of KTX. Reviews of the running stability and the riding comfort were carried out with the results of the measurement and the analyses of vibration acceleration, endrotation, distortion and deflection at midspan.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.6 no.2
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• pp.121-126
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• 2006

In the recent years, the development of computer-controlled suspension dampers and actuators has improved the trade-off between the vehicle handling and ride comfort, and has led to the development of various damper control policies. The skyhook control is an effective control strategy for suppressing vehicle vibration. In this study, a fuzzy skyhook control is proposed and tuned by a genetic algorithm to improve ride comfort. The proposed fuzzy skyhook control is applied to a quarter-car model in order to compare its performance with continuous skyhook suspensions. To obtain optimized fuzzy skyhook control, scale factors and in-out membership functions are tuned by a genetic algorithm. The simulation results show that the fuzzy skyhook control offers more effective suspension performance over the continuous skyhook control.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2002.05a
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• pp.209-212
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• 2002

This article introduce Comfort Class V released by Dnv The Class has an objective of classifying ships by noise and vibration levees. It is apparent that noise criteria listed in the Class can not be satisfied without special efforts to enhance sound insulation performance in cabins. Accordingly, panel makers should develope panels which have very high sound insulation performance enough to satisfy the criteria. Also, due to large difference of sound insulation performance between cabin and laboratory, it is necessary that ship yards should improve the method for installing cabins.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.188-193
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• 2007

Airport railroad have required maximum design speed 120km/h and wind speed 50m/s condition as design item of airport railroad vehicles. To design and manufacture the vehicle satisfying these conditions, it must carry out the dynamic behaviors analysis such as hunting stability, ride comfort derailment ratio, unloading ratio and lateral force to meet the criterion described in Urban Railroad Act. Dynamic behaviors of vehicle have carried out using the multi-body dynamics simulation program(VAMPIRE). This paper presents the evaluation methods and criterion used to verify dynamic performance of airport railroad vehicle, and show the analysis results of vehicle dynamic simulation and the test results for vibration and ride comfort measured on running performance tests. As a results, each analysis results and test results meet the criterion described in Urban Railroad Act.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.28-35
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• 2003

In this paper, the ride comfort of a passenger coach installed with a KT23 type bogie was measured and evaluated through field test in operation routes. The ride comfort level was evaluated and analysed by ISO method and DIC method that were applied generally at railway fields. Particularly three evaluation methods, i.e., a simple method, a full standing method, and a full seating method of UIC513R standard, were fully applied to evaluate the ride quality. Also the vertical and lateral vibration levels on the floor were evaluated by peak-to-peak analysis method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.4
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• pp.266-273
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• 2003

The purpose of this study is to obtain the effects of the parameters of the suspension system in railway rolling-stock for KT-23 type Passenger vehicle. According to the analysis and the small scale model car test. optimal condition was obtained for the stiffness ratio of secondary spring to primary spring of the suspension system and the mass ratio of the bogie frame to the car body. The analysis of the study shows that if the car body mass is increased or secondary stiffness Is lowered, the vertical vibration level is reduced and the passenger comfort can be improved. Especially, strong peaks are occurred in the frequencies corresponding to the rotational speed of driving axle and vehicle wheel. Hence, in order to obtain the dynamic characteristics through the small scale model car, the driving method of the vehicle on the test bench, rotational characteristics of the wheel and the natural modes of vehicle should be investigated and be modified.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.6_spc
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• pp.644-650
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• 2016

Track maintenance works based on track geometry recordings are essential to enhance the safety and comfort of railway transportation. Usually, the track irregularity has been measured by a special inspection trains which all were imported from abroad. Because the inspection train speed is limited under 160 km/h, it takes a long time to inspect railways and there is difficulty in daytime operation. To solve this problem, we started to develop a track geometry measuring system (TGMS) with measurement speed up to 300 km/h which can be installed in commercial vehicles such as HEMU-430X. In this paper, we introduce a newly developed inertial TGMS and propose two inertial navigation system (INS) algorithms (method A, B) for measuring track geometry. In order to investigate advantage and disadvantage of each algorithm, we performed vibration test of the TGMS, which was simulated by 6-axis shaking table. Through the vibration test, we analyzed the influence of vehicle vibration on the TGMS which will be installed on bogie frame. To the vibration test, two methods satisfied the required accuracy of track geometry measurement under the level of the actual vehicle vibration of HEMU-430X train. Theoretically, method A is sensitive to vehicle vibration than method B. However, HEMU-430X's bogie vibration frequency range is out of interest range of measurement system. Therefore, method A can also apply the HEMU-430X train.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.3
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• pp.442-453
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• 2016

A significant source of vibration in helicopters is the main rotor system, and it is a technical challenge to reduce the vibration in order to ensure the comfort of crew and passengers. Several types of passive devices have been applied to conventional helicopters in order to reduce the vibration. In recent years, helicopter manufacturers have increasingly adopted active vibration control systems (AVCSs) due to their superior performance with lower weight compared with passive devices. AVCSs can also maintain their performance over aircraft configuration and flight condition changes. As part of the development of AVCS software for light civil helicopter (LCH) applications, a test bench is constructed and vibration control tests and simulations are performed in this study. The test bench, which represents the airframe, is excited using a pair of counter rotating force generators (CRFGs) and a multiple input single output (MISO) AVCS that consists of three accelerometer sensors and a pair of CRFGs; a filtered-x least mean square (LMS) algorithm is applied for the vibration reduction. First, the vibration control tests are performed with uniform sensor weights; then, the change in the control performance according to changes in the sensor weight is investigated and compared with the simulation results. It is found that the vibration control performance can be tuned through adjusting the weights of the three sensors, even if only one actuator is used.

• Journal of the Korean Society for Railway
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• v.11 no.6
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• pp.543-549
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• 2008

The ride comfort is more important according to train speedup. Generally it is defined as the vehicle vibration. There are many studies on evaluation method of ride comfort for railway. But the ride comfort for Korean high speed train (HSR 350x) has been assessed by statistical method according to UIC 5l3R. In this paper, the ride indices, which were measured in the Korean high speed train. have been analyzed and reviewed by using the inferential statistics such as t-test, variance analysis (ANOVA) and regression analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.561-566
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• 2013

This study aims to develop the control system of vehicle height and apply this developed system to common passenger car. The vibration characteristics to affect ride comfort are examined through driving tests. The hydraulic control system of vehicle height is designed by Macpherson type used most commonly at current passenger car. Tests in this study are operated by the vehicle installed with genuine suspension system of Macpherson type, tuning suspension system and hydraulic control system of vehicle height. As vibration characteristics transmitted to vehicle become random types values of PSD(Power Spectrum Density) are compared.