• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.36-41
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• 1988

Analog and Digital Speed Control Systems have mutually complementary properties. Analog System has good dynamic characteristics and moderate steady-state accuracy and can be implemented economically with operational a ampliers. Digital System, on the contray, has good static accuracy, but relatively poor dynamic property. So, a hybrid system which uses both digital and analog control can have good static and dynamic characteristics. In this paper, it is shown that a simple digital controller can improve steady-state accuracy of existing analog control system satisfactorily, and some design criteria are presented also.

• Macromolecular Research
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• v.9 no.3
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• pp.157-163
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• 2001

The influences of carbon black loading and cure type on the cure characteristics including kinetics and dynamic mechanical properties were investigated for a styrene-butadiene rubber (SBR). The rate constants of accelerated sulfur vulcanization reaction at three different temperatures were determined using a cure rheometer, and they were compared with those from the direct measurement of sulfur concentration. The strain softening behavior under dynamic deformation, known as the Payne effect was also discussed depending on the carbon black loading and cure type.

• Education of Primary School Mathematics
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• v.9 no.1 s.17
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• pp.59-64
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• 2005

The purpose of this study is to find out how to use dynamic geometry software such as the Geometer's Sketchpad in elementary math classroom. Fist of all, I reviewed dynamic geometry software's property. Then I considered methods to improve geometry education using this software. Some researchers proposed three types of using the software. But I think using the software and developing instructional materials is different. So, I proposed two types of developing instructional materials using the software and two representative examples.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.337-343
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• 2006

Numerical calculations are made in order to find a possible correlation between the J-integral and the crack mouth opening displacement(CMOD) in dynamic nonlinear fracture experiments of 3-point bend(3PB) specimens. Both elastic-plastic and elastic-viscoplastic materials are considered at different impact velocities. The J-integral may be estimated from the crack mouth opening displacement which can be measured directly from photographs taken during dynamic experiments.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1495-1500
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• 2011

Dynamic cipher has the property that the key-size, the number of round, and the plain text-size are scalable simultaneously. In this paper we propose the block cipher algorithm which is symmetrical in the dynamic network. We present the method for designing secure Dynamic cipher against meet-in-the-middle attack and linear crytanalysis. Also, we show that the differential cryptanalysis to Dynamic cipher is hard.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.759-764
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• 2010

In this study, from the comparison of the results obtained by 3 dimensional dynamic analyses using the inverse-calculated properties and those by calculating using the real earthquake records, the inverse calculation method for obtaining the dynamic properties of rockfill materials was verified. The fundamental frequency of the dam was determined by analyzing the response spectrum of observed records. By repeated dynamic analyses for various shear moduli of rockfill material, the shear moduli in the rockfill zone that satisfy the relationship between the fundamental frequency obtained by analysis of the observed records and that by numerical analyses were determined. Using the determined shear moduli, the 3 dimensional dynamic analyses for the dam were carried out and the result were compared with the real response characteristics on the crest of the dam.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.249-255
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• 2010

Ballasted track is under the circumstance of repetition of deterioration and recovery. Track deterioration is presented as track irregularity or settlement, and dynamic force subjected to track is one of major cause of the deterioration. The dynamic force is determined from the dynamic interaction between track and vehicle. Rail-pad stiffness is one of the factor affects track dynamic property. In this study, the relationship between rail-pad stiffness and track settlement was investigated. Dynamic forces according to various rail-pad stiffness was obtained from the dynamic vehicle-track interaction analysis using DARTS-NL. Track settlement was calculated by substitution the dynamic forces into various formulas for track settlement. From the result of analysis, it was known that the track settlement is increased about 6% when the rail-pad stiffness rise about twice. And this result leads that there is only a little relationship between rail-pad stiffness and track settlement.

• Explosives and Blasting
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• v.38 no.3
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• pp.30-43
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• 2020

Rock dynamics is a relatively new discipline to study the mechanical behaviors of rock materials (or rock masses) under dynamic loading conditions. Many rock mechanics and rock engineering issues are concerned with the dynamic phenomena such as mining development, civil engineering, earthquake, military science, and various disasters. The significance of rock dynamic researches has been increased in these days. This paper introduces conventional experimental techniques for rock dynamic experimental methods and the particular characteristics of rock dynamic behaviors with several remarkable recent studies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.4
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• pp.179-189
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• 1999

This study attempts to propose an evaluation considering the property of concrete pore which affects the deterioration of neutralization and the rebar resistance of concrete. Understanding pore property of concrete in using extent, for practical using of concrete manufacturing condition. basic quality property and durability estimation etc, the results of the experiment are as follows. 1) The result of analysis pore property of every specimen with the method of area ratio, in limitation of $10^{-6}{\sim}10^{-5}m$, the pore distribution ratio was maximum. It was high value as W/C was increased and the unit cement content was decreased. 2) In case of using admixture. the volume of pores was some increased as variation of mixing content. In high W/C range, it was very increased compared with plain concrete. 3) Concerned with compressive strength and volume of pores in hardened concrete, it is possible compressive strength estimation using the property of concrete pores. 4) Direct measurement of concrete pore property is difficult. the valuation of the dynamic modulus of elasticity using ultrasonic wave velocity was available. 5) Quantitatively evaluation of concrete structure durability by past result of pore distribution estimation, and it can be estimative scale of property study on the concrete materials.

• Journal of Adhesion and Interface
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• v.23 no.3
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• pp.87-93
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• 2022

To analyze the interfacial property between the fiber and the matrix, work of adhesion was used generally that was calculated by surface energies. In this paper, it was determined what types of contact angle measurement methods were more accurate between static and dynamic contact angle measurements. 4 types of glass fiber and epoxy resin were used each other to measure the contact angle. The contact angle was measured using two types, static and dynamic contact angle methods, and work of adhesion, W_a was calculated to compare interfacial properties. The interfacial property was evaluated using microdroplet pull-out test. Generally, the interfacial property was proportional to work of adhesion. In the case of static contact angle, however, work of adhesion was not consistent with interfacial property. It is because that dynamic contact angle measurement comparing to static contact angle could delete the error due to microdroplet size to minimize the surface area as well as the meniscus measuring error.