• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.83-95
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• 2020

In order to evaluate the stability of the geo-structure of railway bridge, the response dominant frequency was analyzed based on a series of impact vibration load test results. The specifications of the experiment piers were obtained by referring to the completion design data, and when data was missing, a field study was conducted. The impact vibrations test according to the scouring progress was carried out at one pier scheduled to be abandoned, and it was confirmed that the response dominant frequency can be utilized as an evaluation index for scour. In addition, the response dominant frequency was measured through an impact load test at 46 piers in 5 bridges in operation, and the scour safety of the bridge was evaluated by comparing it with the japanese proposal formula.

• Journal of Power System Engineering
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• v.4 no.2
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• pp.71-76
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• 2000

It is well known that finite element analysis often has the inaccuracy when they are in conflict with test results. Model updating is concerned with the correction of analytical model by processing records of response from test results. This paper introduce a model updating technique using the frequency response function data. The measurement data is able to be used directly in the FRF sensitivity method because it is not necessary to identify. When a damping model is updated, it is necessary for the sensitivity matrix to be divided Into the complex part and real part. As an applying model, a cantilever and a rotor system are used. Specially the machined clearance($C_p$) of the journal bearing is updated.

• Journal of the Korea Institute of Military Science and Technology
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• v.8 no.3 s.22
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• pp.73-82
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• 2005

This paper describes shock waveform synthesis methods for a shock response spectnlm over a short time interval with which intereference between parts within a test item is increased to perform a sufficient shock test for damage or malfunction which may be caused by the interference between parts, and a digital filter for obtaining a shock response history required for the shock waveform synthesis and a digital inverse filter for restoration by inversely using the digital filter. The time at which the maximax value occurs in the response history is detected in order to establish a delay time which is one of the parameters in the wavelet, on the condition that the natural frequency of SDOF system with a Q (quality factor) of 10 equals to the wavelet frequency of the zero delay wavelet input. A shock response spectrum over a short time interval and an abrupt change in the acceleration for an instant are illustrated as features of the synthesized waveform.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.1134-1139
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• 2007

In recent years, public complaints about railroad noise by KTX and Ordinary train are increasing. Restriction of railways uses same standard without distinguishing the type of railways. According to the type of railways, the frequency characteristics of emitting noise is different. Therefore it is requested to know how vary the public response to each types of railway. The noise annoyance to three types of trains (KTX, Electric train, Diesel train) was analyzed by Jury Evaluation Test for assessing the effect of frequency characteristics. The numerical results by a Semantic Differential Method showed that annoyance response to three type of trains depended on the frequency characteristics. As a result, this study proposed that the KTX could have a bonus level of maximum 2.9dB(A) to ordinary train.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.389-394
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• 2011

Existing FPS(Friction Pendulum System) is isolation system which is possible to isolate structures by pendulum characteristic from ground vibration. Structural natural frequency could be decided by designing the radius of curvature of FPS. Thus, response vibration could be reduced by changing natural frequency of structures from FPS. But effective periods of recorded seismic wave were various and estimation of earthquake characteristic could be difficult. If effective periods of seismic wave correspond to natural frequency of structures with FPS, resonance can be occurred. Therefore, CFPBS(Cone-type Friction Pendulum Bearing System) was developed for controlling the response acceleration and displacement by the slope of friction surfaces. Structural natural frequency with CFPBS can be changed according to position of ball on the friction surface which was designed cone-type. Therefore, Divergence of response could be controlled by CFPBS which had constantly changing natural frequency with low modal participation factor in wide-range. In this study, Seismic performance of CFPBS was evaluated by numerical analysis and shaking table test.

• Journal of Auto-vehicle Safety Association
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• v.12 no.3
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• pp.27-33
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• 2020

In this paper, the process of predicting efficient durability performance for vibration durability test of automobile parts using vibration test load on automobile fuel tank is presented. First of all, the common standard load that can be applied to the initial development process of the automobile was used for the fuel tank and the vulnerability of the fuel tank to the vibration fatigue load was identified through frequency response analysis. In addition, the vulnerability of the fuel tank was re-enacted through vibration durability test results, and the scale factor was applied to the standard load. In order to predict the vibration durability performance required for detailed design, vibration fatigue analysis was performed on the developed vehicle with the frequency of vibration severity equivalent to the durability test, and the vulnerability and life span of the fuel tank were identified through the process of applying weights to these selected standard loads, thereby reducing the test time of the development vehicle.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1231-1234
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• 2003

Pneumatic servo valve which is widely applied in industrial world is advanced technology compounded with electric, electronic and machine. And It is consist of Linear Force Motor. Spool Commutation Mechanism and Microprocessor. In this study, we accomplished test method of Linear Force motor test, Static characteristic test, Dynamic characteristic test for KS(Koran industrial standard) of Pneumatic servo valve. we accomplished study about the main item of Static characteristic test which is related to unload flow characteristic test. And Dynamic characteristic test was step input test and frequency response test. Specially about frequency response test, There was a difficulty resulting from the time delay problem caused by the basic compressibility of air. In order to solve the problem in this study. we proposed two methods. First, displacement of the servo valve spool was directly measured by using a laser sensor. Second, method of calculating control flow by measuring pressure and temperature of chamber.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.7
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• pp.2108-2117
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• 1996

The purpose of this paper is to investigate the influence of the exciter attached for the measurement of natural frequencies when extracting the frequency response functions of the test structure in experimental modal analysis. The procedure is first to model the attached exciter as an additional degree of freedom system and next to verify the suggested model by experimentally extracting the natural frequencies of the test structure with various values of exciter mass, stinger stiffness and attachment position of the exciter on the test structure. It is concluded that as additional degree of freedom system which includes the natural frequency of the exciter itself and axial stiffness of stinger should be considered to quantatively define the coupling effects of structure-exciter interaction on the measured natural frequencies. It is not the mass of the exciter itself but the coupling effect of the additional degree of freedom mass-spring system consisting of exciter body and armature coil that characterizes the natural frequency deviation. Therefore, when the natural frequency of this additional mass-spring system is outside of the test frequency range, the coupling effect of structure-exciter interaction can be minimized.

• Journal of the Korea Fashion and Costume Design Association
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• v.18 no.4
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• pp.87-99
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• 2016

The purpose of this study was to investigate the appearance orientation and clothing and cosmetics purchasing behaviors according to media contact responses. The subjects were 445 female university students in Daejeon and Chungnam province. The measuring instruments was a questionnaire with media contact responses, appearance orientation, clothing and cosmetics purchasing behavior, and subjects' demographic characteristics. The data were analyzed by Cronbach's ${\alpha}$, frequency analysis, ${\chi}^2$ test, ANOVA, Duncan's multiple range test, and regression analysis using SPSS program. The results were as follows. First, female university students had very positive response and attitude on entertainers' appearance, style and products showed by media. Second, media contact response had a significant effect on appearance orientation. The group with a high level of media contact response showed higher appearance orientation than the groups with mediate and low level of media contact response. Third, media contact response had meaningful effects on clothing and cosmetics purchasing behaviors. The group with a high level of media contact response showed higher shopping frequency, purchasing frequency, and more spending on clothing and cosmetics than other groups.

• The Journal of Korea Robotics Society
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• v.6 no.1
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• pp.34-41
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• 2011

This paper presents a frequency-response test performed on an antagonistic actuation system consisting of two Mckibben pneumatic artificial muscles and a pneumatic circuit. A linear model, capable of estimating the dynamic characteristics of the antagonistic system in the operating range of pneumatic artificial muscles, was optimally calculated based on frequency-response results and applied to a multiple simultaneous specification control scheme. Trajectory tracking results showed that the presented multiple simultaneous specification controller, built experimentally by three PD typed sample controllers, satisfied successfully all required control specifications; rising time, maximum overshoot, steady-state error.