• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.149-150
• /
• 2006

The design of a measurement system to perform Harmonic State Estimation (HSE) is a very complex problem. In particular, the number of harmonic instruments available is always limited. Therefore, a systematic procedure is needed to design the optimal placement of measurement points. This paper presents a new HSE algorithm which is based on an optimal placement of measurement points using Intelligent Algorithms (IAs). This HSE has been applied to the Simulation Test Power System for the validation of the new HSE algorithm. The study results have indicated an economical and effective method for optimal placement of measurement points using Intelligent Algorithms (IAs) in the Harmonic State Estimation(HSE).

• Proceedings of the KIEE Conference
• /
• 2005.07a
• /
• pp.304-306
• /
• 2005

This paper presents the RTDS training course on using passive filters for control of harmonic currents. The course can show harmonic currents in porer system, which is occurred by function generators, with Fourier analysis function of RTDS and the effect of passive filters implemented in RTDS to eliminate harmonics. In addition to, With Jeju-Haenam HVDC system, we have simulated the effect of passive filters on harmonic currents occurred by massive power conversion system of HVDC.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.273-277
• /
• 2003

This paper presents a structure of the Wilkinson power divider that can suppress the 9ea harmonic output. The power divider consists of ${\lambda}/4n$ open stubs, which are located at the $3{\lambda}/4$ branches and parallel connection of resistor which shunts the output ports. Experimental results show that this power divider suppresses from 1st to 9th harmonic components to less than -37dB, while maintaining the characteristics of a conventional Wilkinson power divider; featuring an equal power split, a simultaneous impedance matching at all ports and a good isolation between output ports. these results agree quite well with the simulation results.

• Kyungpook Mathematical Journal
• /
• v.47 no.1
• /
• pp.105-118
• /
• 2007

In this paper, we first define a new kind of two-weight-$A_r^{{\lambda}_3}({\lambda}_1,{\lambda}_2,{\Omega})$-weight, and then prove the imbedding inequalities for $\mathcal{A}$-harmonic tensors. These results can be used to study the weighted norms of the homotopy operator T from the Banach space $L^p(D,{\bigwedge}^l)$ to the Sobolev space $W^{1,p}(D,{\bigwedge}^{l-1})$, $l=1,2,{\cdots},n$, and to establish the basic weighted $L^p$-estimates for $\mathcal{A}$-harmonic tensors.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.4
• /
• pp.172-176
• /
• 2005

Power system restoration following a massive or complete blackout starts with energizing of primary restorative transmission lines. During this primary restoration, inexpected overvoltage may happen due to nonlinear interaction between the unloaded transformer and the transmission system. This is known as the harmonic resonance phenomenon that may cause burning out of transformer or other devices. By now the harmonic resonance is reported in the extra high voltage system. This paper reports the detection of the resonance in Korean power system. Basic analysis and simulation of the harmonic overvoltage is presented using EMTDC.

• Proceedings of the KIEE Conference
• /
• 2003.11a
• /
• pp.31-33
• /
• 2003

Power system restoration following a partial or complete blackout starts with energizing of primary transmission lines. Because system changed rapidly during early restoration process, transformer energization and load pickup is executed to maintain the power system stability. However unexpected problem such as harmonic overvoltage may be arisen during energizing transformer. The reason of harmonic overvoltage is known as transformer saturation and magnetizing in-rush current and so on, but it is difficult to estimate the condition of occurrence. This paper describes the analysis of the harmonic overvoltage while unloaded transformer is energized using PSCAD/EMTDC.

• Transactions on Electrical and Electronic Materials
• /
• v.17 no.4
• /
• pp.217-221
• /
• 2016

In this work, open and short stubs that were fabricated on the silicon substrate and for which the periodically arrayed grounded-strip structure (PAGS) was employed were studied along with their basic RF characteristics for an applicability regarding the RF-matching components. The PAGS-employing open and short stubs showed losses that are much lower than that of the conventional stub on the silicon substrate. Concretely, the Q values of the open and short stubs are 9 and 10.2, respectively, while the Q value of the conventional open stub is 2.5. With the use of the PAGS-employing open and short stubs, a highly miniaturized harmonic-rejection filter was also fabricated on the silicon substrate. The filter exhibited a comparatively sound harmonic-suppression characteristic at n × 13 GHz, and its size is 0.1 mm², which is only 7% of the size of the conventional filter on the silicon substrate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.25 no.1
• /
• pp.53-61
• /
• 2014

In this paper, we present the design, fabrication and measurement of high efficiency GaN HEMT power amplifier using harmonic matching technique. In order to achieve high efficiency, harmonic load-pull simulation is performed, that is, the optimum load impedances are determined at $2^{nd}$ and $3^{rd}$ harmonic frequencies as well as at the fundamental. Then, the output matching circuit is designed based on harmonic load-pull simulation. The measurement of the fabricated power amplifier shows the linear gain of 20 dB and $P_{1dB}$(1 dB gain compression point) of 33.7 dBm at 1.85 GHz. The maximum power added efficiency(PAE) of 80.9 % is achieved at the output power of 38.6 dBm, which belongs to best efficiency performance among the reported high efficiency power amplifiers. For W-CDMA input signal, the power amplifier shows a PAE of 27.8 % at the average output power of 28.4 dBm, where an ACLR (Adjacent Channel Leakage Ratio) is measured to be -38.8 dBc. Digital predistortion using polynomial fitting was implemented to linearize the power amplifiers, which allowed about 6.2 dB improvement of an ACLR performance.

• Journal of the Korean Chemical Society
• /
• v.54 no.4
• /
• pp.387-394
• /
• 2010

The theoretical calculations for $B_nH_n$, $B_nH_{n+1}$, $B_nH_{n+2}$ (n = 3-6) have been considered at the B3LYP level of theory with the 6-311G$^*$ basis set. The optimized geometries, harmonic vibrational frequencies, and binding energies are evaluated to elucidate the thermodynamic stability and spectroscopic properties. The harmonic vibrational frequencies for the molecules considered in this study show all real numbers implying true minima and the binding energies are corrected using zero-point vibrational energies (ZPVE). The binding energies and average energies due to increasing of BH monomer are predicted.

• Bulletin of the Korean Mathematical Society
• /
• v.38 no.4
• /
• pp.773-786
• /
• 2001

On the setting of the half-space of the Euclidean n-space, we consider harmonic Bergman spaces and we also study properties of the reproducing kernel. Using covering lemma, we find some equivalent quantities. We prove that if lim$ lim\limits_{i\rightarrow\infty}\frac{\mu(K_r(zi))}{V(K_r(Z_i))}$ then the inclusion function $I : b^p\rightarrow L^p(H_n, d\mu)$ is a compact operator. Moreover, we show that if f is a nonnegative continuous function in $L^\infty and lim\limits_{Z\rightarrow\infty}f(z) = 0, then T_f$ is compact if and only if f $\in$ $C_{o}$ (H$_{n}$ ).