• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.4
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• pp.596-602
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• 2008

This paper presents the dynamic characteristic analysis of Permanent Magnet Linear Synchronous Motor(PMLSM) according to variable load. In order to analyze dynamic characteristics, finite element method(FEM) was used for calculation of the parameter and the Matlab simulink was used for dynamic characteristic simulation. The measuring system of the dynamic characteristics was manufactured and the experiment results were compared with the simulation results.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.3
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• pp.181-188
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• 2007

This paper presents a torque control method of a hydraulic actuation system for measuring the dynamic stiffness of missile fin actuators. We propose a new control technique called Dual Dynamic Torque Feedback Control(DDTFC), which improves the stability of the torque control system and enables fast tracking of torque command. The developed control scheme is derived from the physical understanding based on mathematical modelling and analysis. The dynamics of hydraulic torque control servo-system is unravelled via physics-based modelling and nonparametric system identification. In order to verify the effectiveness of the method, the experiment is carried out with a test equipment for measuring the dynamic stiffness. The experiment and simulation results show that DDTFC gives stability improvement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.1256-1259
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• 2006

The purpose of this study was to investigate the current status and influence factor in measuring the dynamic stiffness of damping materials. The property of the dynamic stiffness of damping materials was tested and analysed in condition such as the size of test samples and the change of relative humidity in heating chamber. Test results showed that the dynamic stiffness of after-heating was lower than that of before-heating in most samples and the change of relative humidity in heating chamber got little influence of the dynamic stiffness. The resonant frequency of test sample decreased $2{\sim}7Hz$ as the decrease of the size of sample. Because it was increased that total mass per unit area of sample, the change of dynamic stiffness had little influence.

• Korean System Dynamics Review
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• v.2 no.1
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• pp.69-92
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• 2001

The Managing and measuring performance have long been a popular topic in business. Traditions of financially-oriented managing and measuring performance have provided managers with relatively objective and scientific results of measuring performance until now. But today the value of organization is influenced more by intangible assets than tangible assets. Nobody thus believes that the performance and the value of organization can be measured by financial indicators only. In this background, numerous researches have been conducted to find alternatives to measuring the value of organization's intangible assets. One of the remarkable achievements would be "Balanced Score Card (BSC), "which covers three sectors of indicators, each from customer relations, internal process innovations, and learning and human resource development, in addition to traditional financial indicators. Unfortunately, even BSC, let alone others, fails to accomodate all performance indicators as a holistic system. Namely, performance measuring techniques including BCS, at present, fail to reflect the dynamic features in their model - i.e., the casual relations and the interactions between the indicators, and there is no way of taking into account the impact of delayed feedback which flows from introduction of new policy and legislative changes, etc. Therefore, this paper attempts to devise a means for adding dynamic features to BSC, by introducing the system dynamics concept, with a focus on the effect of casual relations and feedback structure.

• International Journal of Precision Engineering and Manufacturing
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• v.3 no.3
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• pp.69-75
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• 2002

Measuring dynamic fracture toughness of brittle and small ceramic specimen is very difficult in a SHPB (Split Hopkinson Pressure Bar). As a countermeasure to this difficulty, a dynamic fracture toughness measuring method by the Chevron-notch ceramic specimen was proposed. Tested chevron specimens were of Chevron notch angles of 90$^{\circ}$, 100$^{\circ}$ and 110$^{\circ}$. Through finite element analysis, shape parameters of the Chevron-notch specimens according to notch angles were calculated. And the static fracture tough1ess of the Chevron-notch alumina specimen was measured as 3.8MPa√m similar to that of CT specimen with a precrack. Dynamic fracture toughness was 4.5MPa√m slightly higher than the static one. It was shown in this study that the proposed Chevron-notch specimens are valid to measure dynamic fracture toughness of extremely brittle materials such as ceramic.

• KIEAE Journal
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• v.10 no.4
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• pp.3-8
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• 2010

Recently, various daylight evaluation methods for visual environment have been developed; simulation analysis methods, numerical calculation, and data monitoring methods. However, it is impossible for simulation analysis to make real scenes and visualize real images exactly. Also, a numerical calculation is considered as an out of date and time-consuming mean. Therefore, for acquisition of accurate results, many studies often use the monitoring data methods. Especially, most studies regarding discomfort glare are evaluated by measuring the physical quantity of luminance through traditional measuring Minolta Luminance meters as an instrument. But, this method has a difficulty in measuring several points at the same time because of the limitation of spaces and time when mapping. So, this study focused on the potential usefulness of High Dynamic Range photography technique as a luminance mapping tool. In order to evaluate the accuracy of proposed programs such as webHDR, Photomatix and PHOTOLUX, this paper has conducted an experiment by using Canon EOS 5D and NICON Coolpix8400 digital camera.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.279-282
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• 2005

The aim of this study is to suggest the method of measuring the dynamic stiffness and loss factor of materials used under floating floors in the dwelling by korea standard (KS F 2868). According to the results, the amplitude change of an impact source have no effect on the variation of the dynamic stiffness and loss factor. Comparing with the heating before, heating makes lower the dynamic stiffness except the EPS. In EVA material, the loss factor is increased by heating.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.6
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• pp.133-140
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• 2001

This paper suggests another system for a cutting force measuring tool in a milling process. Generally, tool dynamometer is taken into account for the most appropriate cutting force measuring tool in the analysis of cutting mechanism. However, high price and limited space make it difficult to be in-situ system for controllable milling process. Although an alternative method using AC current of servo-motor has been suggested, it is unsuitable for cutting force control because of small upper frequency limit and noise. The cutting force measuring system is composed of two load cells placed between the moving table bracket and the nut flange part of ballscrew. It has many advantages such as low cost and wide range measurement than tool dynamometer because of the built-in moving table and the low cost load cell. The static and dynamic model of the measuring system using imbeded load cell is introduced. Various Experiments are carried out to validate both models. By comparing the cutting forces from a series of end milling experiments on the tool dynamometer and the system developed in this paper, the accuracy of the cutting force measuring system is verified. Upper frequency limit is measured by the experiment of dynamic characteristics.

• International Journal of Highway Engineering
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• v.14 no.5
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• pp.57-65
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• 2012

PURPOSES: It is important to consider the long-term performance of concrete pavement, because concrete pavement is more exposed to the various environmental conditions than any other concrete structures. One of the several methods to evaluate the long-term performance of concrete during winter is KS F 2456. Relative dynamic modulus of elasticity shows the resistance to freezing and thawing. METHODS: To measure relative dynamic modulus of elasticity, ultra sonic is generally used. But in this study, to measure the relative dynamic modulus of elasticity, both ultra sonic and shear wave were used and then compared each other. RESULTS: The results from the measurement by ultrasonic wave and shear wave were divided into three types. Type 1 : Specimens are good and relative dynamic modulus of elasticity did not decrease until 300 cycle. Type 2 : The relative dynamic modulus of elasticity decreased from the late cycle.(about 150 cycle later) Type 3 : The relative dynamic modulus of elasticity consistently decreased from the beginning. As a result of ANOVA, there is no difference according to measuring method, in type 2 and 3. But there is a difference according to measuring method, in type 1's relative dynamic modulus of elasticity. CONCLUSIONS: It is proved that shear wave can be used to understand the damage tendency of relative freezing and thawing and to measure the relative dynamic modulus of elasticity.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.7
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• pp.1630-1641
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• 1995

The dynamic stress intensity factors (DSIF ; $K_{I}$$^{dyn}$) were studied in some polymeric materials using caustics method with a high speed camera system. Also crack tip propagation speed was measured by dynamic crack propagation velocity measuring device. To calculate DSIF a finite element analysis program-INha Stress Analysis Moving CRack(INSAMCR) was utilized. Dynamic fracture characteristics were investigated to verify a relationship between DSIF and crack tip propagation speed and acceleration in PMMA, Homalite-100 and Polycarbonate. The relationship between dynamic stress intensity factor and crack tip velocity revealed typical shapes. Measured crack tip acceleration data envelope converges to the zero level with increasing DSIF. Equivalently crack tip velocities show a wide spread range at low values of DSIF, but become a constant with a higher DSIF. $1.2MPa{\sqrt{m}}$, $1.4MPa{\sqrt{m}}$ and $1.3 MPa{\sqrt{m}}$ were obtained as $K_{I}$$^{dyn}$ values to arrest the dynamic crack for PMMA, Homalite-100 and Polycarbonate, respectively. INSAMCR was run to verify experimental results in PMMA and shows good agreementment.