• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.177-191
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• 2019

The local topography has a significant effect on the characteristics of seismic ground motion. This paper investigates the influence of topographic effects on the seismic response of a train-bridge system. A 3-D finite element model with local absorbing boundary conditions is established for the local site. The time histories of seismic ground motion are converted into equivalent loads on the artificial boundary, to obtain the seismic input at the bridge supports. The analysis of the train-bridge system subjected to multi-support seismic excitations is performed, by applying the displacement time histories of the seismic ground motion to the bridge supports. In a case study considering a bridge with a span of 466 m crossing a valley, the seismic response of the train-bridge system is analyzed. The results show that the local topography and the incident angle of seismic waves have a significant effect on the seismic response of the train-bridge system. Leaving these effects out of consideration may lead to unsafe analysis results.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.177-184
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• 2006

In this paper a new dc-link type wind turbine generator system using a shaft generator system, which is widely used for power sources in a ship, is proposed. The basic configuration of the proposed wind turbine generating system is first explained. And the equations expressing the system are derived. Then the steady-state characteristics of the generating system are discussed. We use an experimental system that can simulate the characteristics of a wind turbine in this study, because it is hard to operate an actual wind turbine in a laboratory. In addition, the transient responses of this system are investigated when the velocity of the wind is changed. It is shown that experimental results were very close to the simulated ones, supporting the usefulness of the theory.

• Journal of Power System Engineering
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• v.21 no.1
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• pp.5-10
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• 2017

Pitch drive system in wind turbine is composed by the planetary gear system to satisfied its required performance such as long life and light weight for gear train. When the planetary gear system can reduce its volume and weight, the power consumption of the wind turbine can be reduced. In this study, the planetary gear system of the pitch drive system in medium-sized wind turbine is obtained for weight reduction by shape optimization method. And the planetary gear system is verified for their strength by the structural analysis.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.443-451
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• 2015

The stability of a multi-terminal direct current (MTDC) system is often influenced by its control strategy. To improve the stability of the MTDC system, the control strategy of the MTDC system must be appropriately adopted. This paper deals with estimating stability of a MTDC system based on the line-commutated converter based high voltage direct current (LCC HVDC) system with an inverter with constant extinction angle (CEA) control or a rectifier with constant ignition angle (CIA) control. In order to evaluate effects of two control strategies on stability, a MTDC system is tested on two conditions: initialization and changing DC power transfer. In order to compare the stability effects of the MTDC system according to each control strategy, a mathematical MTDC model is analyzed in frequency domain and time domain. In addition, Bode stability criterion and transient response are carried out to estimate its stability.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.819-824
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• 2010

Model test was performed for new earth retention system that is a kind of truss tower with non-supported excavation. For the model test, a dimensional analysis of the full-scaled truss tower system was performed. The horizontal displacement of the wall, bending stress acting on TTS system were measured during construction simulation. From the measurements, the performance of the truss tower system was investigated.

• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.162-168
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• 2014

Recently, researches on all-electric subsea system have been in progress. This paper describes a subsea tree using a lot of electrical signal and subsea control system. The way of subsea control is classified as all-electric systems or electro hydraulic systems. One of that has more merits in terms of cost, weight, power consumption, etc. because it uses electric signal instead of hydraulic signal. This paper describes the difference of each system's power consumption and simulation. As the result, if each system applies the same number of sensors, actuators, etc. The power consumption of all-electric system's load is less than at least 400kWh/day compared to the electro hydraulic system load.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.7
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• pp.919-926
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• 2012

In order to control a LTI(Linear Time Invariant) system subjected to system noise and measurement noise, first of all, it is necessary to estimate the state of system with reliability. Kalman filtering technique has been widely used to estimate the state of the stochastic LTI system with stationary noise characteristics because of its estimation ability versus algorithm simplicity. However, it often fails to estimate the state of the LTI system of which system parameter uncertainty exists partly and/or input uncertainty exists. In this paper, a new estimation technique based on Kalman filter is suggested for stochastic LTI system under parameter uncertainty and/or input uncertainty. A fuzzy estimation algorithm against uncertainties is introduced so as to compensate the state estimate filtered by Kalman filter. In order to verify the state estimation performance of the suggested technique, several simulations are accomplished.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.369-371
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• 2002

The railway power feeding system is divided into AC power feeding system and DC power feeding system. In downtown area. DC power feeding system is used and AC power feeding system is used in intercity railway system. AC power feeding system raises a inductive disturbance that is divided into electrostatic induction and electromagnetic induction. Especially, it has a bad effect on communication lines. So inductive disturbance reduction method has been adopted in many system. In this paper, we deals with the inductive disturbance reduction method of railway power feeding system and of sides affected by inductive disturbance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.763-768
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• 2007

In construction of RC buildings, the quality of shop and detail drawings is very essential for the quality and safety of buildings, Nevertheless, most of thess works are left to site workers and the requirements about bar detailing such as anchorage and splice have been done without rational design and engineering. The purpose of this research is to develop a computer aided drawing system of rebars for RC buildings. The system is based on an integrated structural design system, that is SDP. SDP manages an engineering database for structural design information. It provides all the information needed to draw rebar drawings. The drawing system consists of three modules, 1) Structural Plan Drawing System, 2) Shop Drawing System, and 3) Detail Drawing System. It is expected that not only the productivity of detail drawing works but also the quality and safety of buildings will be improved using the rebar drawing system developed in this research.

• Proceedings of the KSR Conference
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• 2003.05a
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• pp.519-524
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• 2003

Systems engineering test and evaluation technology development program for (Korea) Express Tilting Train(TTX) system in progress is a national large system development program that is not only a large-size and complex but also multi-disciplinary in nature. For the TTX test and evaluation technology development, verification requirements that could verify system function and performance, should be derived from system specification. Hereafter, this could be listed as items of test. System engineering process establish traceability between items of test and system requirements. These tasks could be accomplished by the schema. Using the Core, a system engineering tool, TTX program could be database and similar other system could be developed effectively and efficiency