• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.555-560
• /
• 2003

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site of Korea High Speed Rail Construction Authority (KHRC). since it was developed as G7 Project Plan In 2002. This paper introduces the dynamic test devices in KHST and shows the comparison between the results of test and theoretical computing results which derive from the new model for KHST dynamic behavior. Previous computer simulation model for KHST was developed to review wether the vehicle system was satisfied with the dynamic performance requirements during the design procedure. But It should be applied the results of the parts test for suspension elements in order to compare between the results of computation and real test. Using VAMPIRE Program made by AEA Technology in UK. the new model also was modified. This paper shows that the static wheel loads calculated from new model is similar to test results. For test on high speed line, we prepared the test devices for evaluating the dynamic performances. which was consisted of the accelerometers( based on Kisler Co.) and the data aquisition systems (based on National instrument Co.), and test program coded by LabView 6i program. These lest devices and programs are flexible to extension the channels for adding sensors and connect to the ethernet network. The acceleration of car bodies, bogie frames and axle boxes were compared between the results of computation and test at 150km/. This paper shows that the results of test were high in high frequency band range but similar frequency band range. It might be considered that these differences were caused by the test which did not performed at constant speed for comparison analysis. Also. It will be able to understand the differences and make better results through a lot of tests planed in future.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.1
• /
• pp.119-125
• /
• 2016

This study examined the running dynamic characteristics of a hybrid type wheel-rail high speed train, in which the propulsion method of maglev is applied. A wheel-rail high speed train propelled by a superconducting linear synchronous motor (SC-LSM) is expected to be superior to a maglev train regarding economical and interoperable aspects, still having powerful thrust force as maglev. In this paper, regarding the two methods of applying the SC-LSM to an existing wheel-rail train, to investigate the influences of SC-LSM propulsion on the dynamic characteristics of wheel-rail high speed train, the dynamic model of train including interaction between the rotor and stator of SC-LSM is established. Through the simulation using the model, the influence of the interaction between the rotor and stator of SC-LSM on stability, ride comfort and the effect of guideway irregularity are investigated.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.4
• /
• pp.476-490
• /
• 2016

This paper defines mode shape function of a composite solar panel assumed as Kirchhoff-Love plate for considering a torsional mode of composite solar panel. It then goes on to define dynamic model of a high-agility satellite considering the flexibility of composite solar panel as well as stiffness of a solar panel's hinge using Lagrange's theorem, Ritz method and the mode shape function. Furthermore, this paper verifies the validity of dynamic model by comparing numerical results from the finite element analysis. In addition, this paper performs a dynamic response analysis of a rigid satellite which includes only natural modes for solar panel's hinges and a flexible satellite which includes not only natural modes of solar panel's hinges, but also structural modes of composite solar panels. According to the results, we confirm that the torsional mode of solar panel should be considered for the structural design of high-agility satellite. Finally, we performed optimization of high-agility satellite for minimizing mass with solar panel's area limit using the defined dynamic model. Consequently, we observed that the defined dynamic model for a high-agility satellite and result of the optimal design are very useful not only because of their optimal structural design but also because of the dynamic analysis of the satellite.

• Wind and Structures
• /
• v.20 no.2
• /
• pp.143-168
• /
• 2015

A numerical model for analyzing air-train-track interaction is proposed to investigate the dynamic behavior of a high-speed train running on a track in crosswinds. The model is composed of a train-track interaction model and a train-air interaction model. The train-track interaction model is built on the basis of the vehicle-track coupled dynamics theory. The train-air interaction model is developed based on the train aerodynamics, in which the Arbitrary Lagrangian-Eulerian (ALE) method is employed to deal with the dynamic boundary between the train and the air. Based on the air-train-track model, characteristics of flow structure around a high-speed train are described and the dynamic behavior of the high-speed train running on track in crosswinds is investigated. Results show that the dynamic indices of the head car are larger than those of other cars in crosswinds. From the viewpoint of dynamic safety evaluation, the running safety of the train in crosswinds is basically controlled by the head car. Compared with the generally used assessment indices of running safety such as the derailment coefficient and the wheel-load reduction ratio, the overturning coefficient will overestimate the running safety of a train on a track under crosswind condition. It is suggested to use the wheel-load reduction ratio and the lateral wheel-rail force as the dominant safety assessment indices when high-speed trains run in crosswinds.

• Journal of the Korean GEO-environmental Society
• /
• v.20 no.12
• /
• pp.5-14
• /
• 2019

Recently in Korea, researches on seismic analyses for high-rise buildings in a large city have been increasing because earthquakes have occurred. However, the ground conditions are not included in most of seismic researches and analyses on a high-rise building. Also the influence of the predominant period of a seismic wave is not considered in reality. Therefore, in this study, the influence of the predominant period of a seismic wave on the dynamic behavior of high-rise buildings was analyzed based on the complete system model which can consider the grounds. For this purpose, 2D dynamic analyses based on a linear time history analysis were performed using MIDAS GTS NX, a finite-element based program. Dynamic behavior was analyzed in terms of horizontal displacements, drift ratios, bending stresses, and building weak zones. As a result, in overall, the dynamic response of a high-rise building become bigger as the predominant period of a seismic wave become longer. It was also found that the predominant period had a greater influence than other parameters, ground conditions and peak ground acceleration.

• Journal of the Korean Society for Precision Engineering
• /
• v.20 no.11
• /
• pp.158-165
• /
• 2003

A specific experimental method, the Split Hopkinson pressure bar (SHPB) technique has been widely used to determine the dynamic material properties under the impact compressive loading conditions with strain rate of the order of 10$^3$/s∼l0$^4$/s. In this paper, dynamic deformation behaviors of rubber materials widely used for the isolation of vibration from structure under varying dynamic loading are determined by using plastic SHPB technique. A transition point to scope with the dynamic deformation behavior of rubber-like material is defined in this paper and used to characterize the specifics of the dynamic deformation of rubber materials.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.9
• /
• pp.687-694
• /
• 2014

The mount suppliers are providing limited information on the dynamic characteristics of the mounts to some designers and some manufacturers of the high-precision machines. In this technical study, the experimental review was carried out about dynamic characteristics of five kinds of commercial passive mounts sold in the market. The dynamic characteristics, natural frequency and damping ratio, extracted from experimental tests were compared to the materials supplied by mount makers. In order to predict the performance of the high-precision machines with mounts, exact values of the dynamic characteristics of mounts should be used in the stage of numerical analysis.

• Proceedings of the IEEK Conference
• /
• 2008.06a
• /
• pp.851-852
• /
• 2008

In this paper, we propose a tone mapping method using Non-linear Dynamic Range Normalization (NDRN) for High Dynamic Range (HDR) images. HDR images are not suitable for commercial display devices because dynamic range of HDR images do not match with one of Low Dynamic Range (LDR) display devices. To reproduce a tone of HDR images for LDR displays, tone mapping methods have been proposed such as local and global tone mapping. We introduce NDRN to locate mean of HDR images at the center of LDR. NDRN preserves the details for highlight and shadow. By suppressing the significant luminance change in tone mapping, naturalness of original image can be also preserved. The experimental results show that the proposed method preserves details and naturalness of original images.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.471-474
• /
• 2001

Recently, due to demands of faster speed and extra features for the chip mounters, there has been ever-demanding needs for the basic technology. Until four or five years ago, chip mounters placing 0.3sec/chip were considered to be in the high speed category, but since then it has become a borderline for categorizing high speed machines capable of placing 0.1sec/chip. In this study, in order to analyze the vibration of head generated by the dynamic behavior of x-frame, FEM model is composed and modal analysis is performed to identify the dynamic characteristics of the structure. Those results are compared with the modal test in order to verify the model. In this paper, Several other factors, such as definition of dynamic accuracy, static accuracy and tolerance of the axis settling range, that might affect the dynamic behavior the head are discussed.

• The Mathematical Education
• /
• v.41 no.3
• /
• pp.341-360
• /
• 2002

The purpose of the study was to investigate the effectiveness of dynamic software in solving high school analytic geometry problems compared with traditional algebraic approach. Three high school students who have revealed high performance in mathematics were involved in this study. It was considered that they mastered the basic concepts of equations of plane figure and curves of secondary degree. The research questions for the study were the followings: 1) In what degree students understand relationship between geometric approach and algebraic approach in solving geometry problems? 2) What are the difficulties students encounter in the process of using the dynamic software? 3) In what degree the constructions of geometric figures help students to understand the mathematical concepts? 4) What are the effects of dynamic software in constructing analytic geometry concepts? 5) In what degree students have developed the images of algebraic concepts? According to the results of the study, it was revealed that mathematical connections between geometric approach and algebraic approach was complementary. And the students revealed more rely on the algebraic expression over geometric figures in the process of solving geometry problems. The conceptual images of algebraic expression were not developed fully, and they blamed it upon the current college entrance examination system.