Dongchul Chung

Finite element (FE) model-based dynamic analysis has been widely used to predict the dynamic characteristics of civil structures. FE model updating method based on the hybrid genetic algorithm, by combining genetic algorithm and the modified Nelder–Mead's simplex method, is presented to improve bridge structures' FE model. An objective function is formulated as a linear combination of fitness functions on natural frequencies, mode shapes and static deflections using measurements and analytical r

Recently, according to Eco-technology accelerating, new types of traction motor with the high efficiency and power are demanded. This paper presents that the Hairpin winding is applied to a design of the electric vehicle traction motor for the high efficiency and power density. Generally, the winding method using the toroidal coil has the restriction which is the unnecessary spaces between coils. However the Hairpin winding method can reduce the gap between coils, therefore the space factor is h

We have developed a fully automated dynamic calorimeter, which can measure the dynamic specific heat of a liquid or solid sample as a function of frequency over the range of six decades 0.01 Hz-10 kHz. The shape of a solid sample can be either wire or planar. At low frequencies, the measured quantity corresponds to the usual static specific heat. With this probe, one can study the slow dynamics occurring in condensed matter systems.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This paper analyzed the characteristics of the permanent magnet (PM) type claw-pole stepping motor by using 3-D finite-element analysis (FEA). As the magnetization occurs along the z-axis of the motor, it is necessary to apply 3-D FEA for analysis of the PM type claw-pole stepping motor. Considering the computation time, however, the number of the analysis model is minimized by using the “design of e

Welded headed studs are used to connect steel girders and concrete slabs in steel composite bridges. However, environmental problems related to welded shear connectors have been reported, including noise and dust generation during the replacement and demolition of damaged or worn concrete slabs. To overcome these issues, demountable shear connectors that enable easy replacement of damaged or worn concrete slabs must be developed. However, conventional bolted shear connectors mainly use embedded

FE model-based dynamic analysis has been widely used to predict the dynamic characteristics of civil structures. In a physical point of view, an FE model is unavoidably different from the actual structure as being formulated based on extremely idealized engineering drawings and design data. The conventional model updating methods such as direct method and sensitivity-based parameter estimation are not flexible for model updating of complex and large structures. Thus, it is needed to develop a mo

The purpose of this paper is the optimal design of a single-phase LSPM (Line-Start Permanent magnet motor). A single-phase LSPM has a permanent magnet in the rotor that is same as induction motor. For that reason, the transient characteristics are very different from an induction motor. Therefore, we need the PM design to consider transient and steady-state characteristics. In this paper, we designed a single-phase LSPM that has a high power and a good starting characteristic, and analyzed the p

A new panel design of circular plastic OLED display compared to conventional rectangular display is presented. For narrow bezel, data line is placed at upper half of a circle bezel and power line is connected to bottom half of a circle bezel.

Joint limits and obstacles are troublesome factors of practical robot manipulator operation. This paper suggests a novel redundancy resolution method for 7-degree of freedom (DOF) anthropomorphic manipulator with joint limits and obstacles. And this paper proposes the criterion for setting the bounds of obstacle too. To model and analyze the inverse kinematic problem in position domain, we use arm angle parameterization method. Consequently, we choose an appropriate arm angle which makes the man

We propose a motor speed ripple elimination method using a state dependent disturbance observer (SDDOB). The SDDOB eliminates the state dependent disturbance in the system regardless of the operation frequency, input time delay and output time delay. The SDDOB and a main proportional integral (PI) controller constitute a robust motor speed controller. Experimental results show the effectiveness of the proposed method.