• Proceedings of the KIEE Conference
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• 2008.09a
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• pp.229-230
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• 2008

The investigations included the measurements of volume currents and also internal space charges on epoxy samples of mm thicknesses. The current versus time relations were shown to correspond well with classical forms of dielectric response such as the Curie-von Schweidler model. After the time transient, near steady currents were extremely small and exhibited a significant temperature dependence, similar in relation to the Poole-Frenkel hoping transport model. Equivalent resistances were on the order of $10^{19}$ ohms and represent very weak charge transport. Electrically stimulated acoustic waves were used to quantify the small internal charges that would accumulate within the epoxy. There was a notable homocharge near both anode and cathode. The dielectric response and the internal charge were related to show a consistent model for charge transport within unfilled epoxy.

• Tunnel and Underground Space
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• v.7 no.3
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• pp.230-237
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• 1997

As concrete structure is getting old and decrepit, its inspection and diagnosis is getting important. Therefore, it is necessary to estimate the soundness of structure using non-destructive tests for effective repairs and maintenances. But, applications of non-destructive tests in tunnel have been used restrictively, due to accessibility only from one side in tunnel lining and presence of tunnel installations. Recently, the various non-destructive techniques have been studied. Especially, ground penetrating radar(GPR) and impact echo (IE) methods have been researched for tunnel inspection. In this study, the applicability of impact echo test in tunnel lining inspection has been investigated. This paper described the tunnel inspection for lining thickness and internal flaw using impact echo tests. Model tests were carried out using impact echo test systems on two concrete models, Model I is measuring for lining thickness, Model II is detecting for internal flaw. Also, the test were applied for lining inspections in a tunnel constructed by NATM. From the results of impact echo tests, we have concluded that impact echo test is a very useful and effective technique for inspecting the concrete tunnel linings.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.285-287
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• 2006

The paper treats the nonlinear robust control of Chua's circuit having Chuar's diode as an element based on the internal model principle. The Chua's diode has unknown nonlinear parameters and the circuits parameters are alos assumend unknown. Nonlinear regulator equations are established to obtain 3-fold equilibrium equations on which the output error is zero. Also an internal model of the 3-fold exosystem is constructed for obtaining the control law. Pole Placement method is used for obtaining the feeback control law. Simulation results are presented for tracking the sinusoidal and constant reference input signal. Asymptotic trajectory control and the suppression of chaotic motion in spite of uncertainties in the system are accomplished.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.108.5-108
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• 2002

Recently, the more advanced control technologies are required to deal with the fast and accurate motion in manipulators. For these requirements, many manipulator control methods have been developed such as a computed torque method. This paper proposes a design method, a two-degrees-of-freedom internal model control (TDOF IMC), of the manipulator position control based on combination of the one-degree-of-freedom internal model control (ODOF IMC) system and the disturbance observer. The proposed control scheme is implemented for the position control, which leads the slave manipulator to the desired location by the master arm. The experimental results are presented and discussed through the imp...

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.812-819
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• 2015

This paper presents a new approach for simulating the internal faults of synchronous machines using distributed computing and Large Change Sensitivity (LCS) analysis. LCS analysis caters for a parallel solution of 3-phase model of a faulted machine within the symmetrical component-based model of interconnected network. The proposed method considers dynamic behavior of the faulty machine and connected system and tries to accurately solve the synchronous machine’s internal fault conditions in the system. The proposed method is implemented in stand-alone FORTRAN-based phasor software and the results have been compared with available recordings from real networks and precisely simulated faults by use of the ATP/EMTP as a time domain software package. An encouraging correlation between the simulation results using proposed method, ATP simulation and measurements was observed and reported. The simplified approach also enables engineers to quickly investigate their particular cases with a reasonable precision.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.2311-2312
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• 2008

The investigations included the measurements of volume currents and also internal space charges on epoxy samples of mm thicknesses. The current versus time relations were shown to correspond well with classical forms of dielectric response such as the Curie-von Schweidler model. After the time transient, near steady currents were extremely small and exhibited a significant temperature dependence, similar in relation to the Poole-Frenkel hoping transport model. Equivalent resistances were on the order of 1019 ohms and represent very weak charge transport. Electrically stimulated acoustic waves were used to quantify the small internal charges that would accumulate within the epoxy. There was a notable homocharge near both anode and cathode. The dielectric response and the internal charge were related to show a consistent model for charge transport within unfilled epoxy.

• Journal of Drive and Control
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• v.14 no.4
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• pp.23-28
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• 2017

Time-delay control with internal model (TDCIM) is the controller for robot manipulators that applies the time-delay estimation and the concept of internal model control (IMC). TDCIM is robust against unknown dynamics and non-linear friction like coulomb friction and static friction. It is simple and computationally efficient. This study presents the relationship between the discrete TDCIM and the discrete PID controller. The PID controller is the most popular control law in the real application. But often the PID controller can be difficult to achieve the desired level of control performance. The result in this study provides a good candidate solution to these situations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.221-226
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• 2008

A typical unsteady internal ballistic analysis model was proposed to take account the erosive burning with the variance of local velocity and pressure along grain surface to the axis of a solid rocket combustor. The model introduced in this study showed good agreements with the results of previous research. It was investigated that the combustion pressure, grain length, initial temperature, and vaporization temperature of propellant affect on the erosive burning.

• Journal of the Korean Society of Propulsion Engineers
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• v.13 no.2
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• pp.17-25
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• 2009

A typical unsteady internal ballistic analysis model was proposed to take account of the erosive burning with the variance of local velocity and pressure along the grain surface of a solid rocket combustor. To validate the model of concern in the study, both cases of non-erosive and erosive burning were compared with the previous researches with marginal accuracy. It was quantitatively investigated that the combustion pressure, grain length, initial temperature, and vaporization temperature of propellant affect the erosive burning characteristics.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.2069-2087
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• 2023

In nuclear power plant (NPP) accidents, the containment is subject to high temperatures and high internal pressures, which may further trigger serious chain accidents such as core meltdown and hydrogen explosion, resulting in a significantly higher accident level. Therefore, studying the mechanical performance of a containment under high temperature and high internal pressure is relevant to the safety of NPPs. Based on similarity principles, the 1:3.2 scale model of a prestressed concrete containment vessel (PCCV) of a NPP was designed. The loading method, which considers the thermal-pressure coupling conditions, was used. The mechanical response of the PCCV was investigated with a simultaneous increase in internal pressure and temperature, and the failure mechanism of the PCCV under thermal-pressure coupling conditions was revealed.