• Proceedings of the KIEE Conference
• /
• 2007.10c
• /
• pp.47-49
• /
• 2007

This paper deals with the generating characteristic analysis of permanent magnet (PM) machines with multi-pole rotor and 3-phase stator windings considering losses such as copper loss, iron loss and mechanical loss. First, using d-q transformation, dynamic equations of PM machines are established. And then, characteristic equations for losses, power and efficiency are also derived. On the basis of d-q dynamic equations and characteristic equations, dynamic simulation algorithm is achieved by the MATLAB/SIMULINK. The simulation results are validated extensively by finite element (FE) analyses.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2000.10a
• /
• pp.573-576
• /
• 2000

In this paper, analysis of operating characteristics of hybrid cascade multilevel PWM rectifier without bulky and heavy isolation transformers is presented. The multilevel PWM rectifier is analyzed by using the circuit DQ transformation whereby the static and dynamic characteristics and some useful design relationships are obtained. Then, the operating characteristics such as active/reactive power relationships with respect to control variables, DC voltages build up are presented. It will be shown that the DC voltages for the multilevel output generation may be directly built up from AC utility source. Finally, to confirm the validity of the analysis, MATLAB simulations are tarried out.

• Proceedings of the KIEE Conference
• /
• 1988.11a
• /
• pp.115-117
• /
• 1988

The algorithm presented here achieves mathematically better decoupling of the MW-$\theta$ and MVARE Calculations by applying linear transformations to load flow equation on paired initial power. The linear transformations to decouple Jacobian matrix prove to be highly profitable considering both Convergence characteristics and computation time per iteration to those required by the FDLF, because the decoupling does not rely on the assumption that the transmission lines have high X/R ratios.

• Proceedings of the KIEE Conference
• /
• 1998.11c
• /
• pp.1033-1036
• /
• 1998

In this research project, two aspects of small signal stability are studied: improvement in Hessenberg method to compute the dominant electromechanical oscillation modes and siting FACTS devices to damp the low frequency oscillation. Fourier transform of transient stability simulation results identifies the frequencies of the dominant oscillation modes accurately. Inverse transformation of the state matrix with complex shift equal to the angular speed determined by Fourier transform enhances the ability of Hessenberg method to compute the dominant modes with good selectivity and small size of Hessenberg matrix. Any specified convergence tolerance is achieved using the iterative scheme of Hessenberg method. Siting FACTS devices such as SVC, STACOM, TCSC, TCPR and UPFC has been studied using the eigen-sensitivity theory of augmented matrix. Application results of the improved Hessenberg method and eigen-sensitivity to New England 10-machine 39-bus and KEPCO systems are presented.

• Proceedings of the KIEE Conference
• /
• 2005.05a
• /
• pp.281-283
• /
• 2005

Processing Plasmas are very sensitive to a variation in process parameters, To maintain process quality and device field, plasma malfunction should be tightly monitored with high sensitivity. A new monitoring method is presented and this was accomplished by applying discrete wavelet transformation to X-ray photoelectron spectroscopy. XPS data were collected during a plasma etching of silicon carbide. Various effects of DWT factor on fault sensitivity were optimized experimentally. Compared to raw data, total percent sensitivity for DWT data demonstrated a significantly improved sensitivity to plasma faults induced by bias power.

• Journal of the Semiconductor & Display Technology
• /
• v.2 no.3
• /
• pp.25-30
• /
• 2003

In this study, the controller using TMS320LF2407 low voltage DSP for motor control is designed and realized. It has 40 MIPS calculating ability and its driving voltage is 3.3 V for low power. The peripheral elements, however usually use 5 V and they need voltage transfer interface. In this study, voltage transformation and reducing noise are studied and space vector PWM is adopted as a motor control scheme. According to these methods, the efforts for software programming and calculation processes are reduced. In addition, the hardware is also simplified by substituting the current control part with software programming. Through this study, the DSP based servo controller increases its ability for high performance multi-function on semiconductor transportation equipments..

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.355-355
• /
• 2006

In this study, we have applied principal component analysis-based 2D (PCA2D) correlation spectroscopy to the temperature-dependent IR spectra of biodegradable poly(hydroxyalkanoate). PCA2D analysis reveals clearly that there are two components in crystalline band of C=O stretching mode without being hampered by noise. To better understand the thermal behavior of biodegradable poly(hydroxyalkanoate), eigenvalue manipulating transformation (EMT) technique was also employed. By uniformly lowering the power of a set of eigenvalues associated with the original data, the subtle contributions from minor eigenvectors are highlighted. Details of thermal behavior of biodegradable poly(hydroxyalkanoate) studied by PCA2D correlation spectroscopy with EMT will be discussed.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.11a
• /
• pp.117-120
• /
• 2008

The Purpose of this is properties of CFT filled with expansion concrete. CFT(concrete filled steel tube) is the structure that circle shape steel column filled with concrete. 3 kinds of expansive additives and variation of replacement rate. we changed expansive additive from 0%, 10%, 20%, 30% of ratio of addition rate are selected for this experiment. Merits of CFT are concrete internal force rising influenced by steel shape restriction, reinforcing the local buckling, excellent resistance to transformation. Generally, High rise building using CFT utilize the high strength and fluidity concrete for packing the tube inside. As the result a steel tube charged expensive concrete has stiffness 1.5times more than a steel tube not charged concrete. Increase of resisting power about compressive stress by binding expansion of expansive concrete affects strength increase and softness.

• Proceedings of the KIEE Conference
• /
• 2002.07a
• /
• pp.127-129
• /
• 2002

This paper presents a fuzzy-GA method to resolve dispersed generator placement for distribution systems. The problem formulation considers an objective to reduce power loss costs of distribution systems and the constraints with the number or size of dispersed generators and the deviation of the bus voltage. The main idea of solving fuzzy nonlinear goal programming is to transform the original objective function and constraints into the equivalent multi-objectives functions with fuzzy sets to evaluate their imprecise nature and solve the problem using the proposed genetic algorithm, without any transformation for this nonlinear problem to a linear model or other methods. The method proposed is applied to the sample systems to demonstrate its effectiveness.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.11a
• /
• pp.367-370
• /
• 2004

This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p,\;k_{15})$ becomes effective rather than the transverse meed coupling factor $(k_{31})$. A single layer prototype transformer, 26[m] in diameter and 2.0[mm] thickness, was fabricated, such as step-up ratio, power transformation efficiency and temperature were measured.