• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.95-96
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• 2006

As the power industry moves towards open competition, there has been a call for methodology to evaluate distribution power system reliability by using customer interruption costs. Accordingly, it is increased for methodology to evaluate distribution power system reliability in power supply zones under competitive electricity market. This paper presents algorithm to evaluate system average interruption duration index. expected energy not supplied and system outage cost taking Into consideration failure rate of distribution facility and industrial customer interruption cost. Also, to apply this algorithm to evaluate system outage cost presented in this paper, distribution system of a dual supply system consisting of mostly high voltage customers in industrial complex in Korea is used as a sample case study. Finally, evaluation results of system interruption cost, system average interruption duration index and expected energy not supplied in sample industrial complex area are shown in detail.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.285-289
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• 2018

In this paper, we demonstrate electromagnetic wave focusing and rectification based on time reversal as a smart method for far-field wireless power transfer. Time reversal in a complex propagation environment allows for transmission of high peak power pulses by focusing the electromagnetic waves selectively regardless of the receiver position. We demonstrate wave focusing and radio frequency (RF) to direct current (DC) rectification via numerical simulation of a complex propagation environment. The results reveal that time reversal can ensure peak power up to 12 dB greater compared to a narrowband continuous wave signal, thereby enhancing the rectified DC voltage with better efficiency.

• Advances in nano research
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• v.14 no.5
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• pp.463-474
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• 2023

The purpose of this paper is to present the analysis of propagating and evanescent waves in functionally graded (FG) nanoplates with the consideration of nonlocal effect. The analytical integration nonlocal stress expansion Legendre polynomial method is proposed to obtain complete dispersion curves in the complex domain. Unlike the traditional Legendre polynomial method that expanded the displacement, the presented polynomial method avoids employing the relationship between local stress and nonlocal stress to construct boundary conditions. In addition, the analytical expressions of numerical integrations are presented to improve the computational efficiency. The nonlocal effect, inhomogeneity of medium and their interactions on wave propagation are studied. It is found that the nonlocal effect and inhomogeneity of medium reduce the frequency bandwidth of complex evanescent Lamb waves, and make complex evanescent Lamb waves have a higher phase velocity at low attenuation. The occurrence of intersections of propagating Lamb wave in the nonlocal homogeneous plate needs to satisfy a smaller Poisson's ratio condition than that in the classical elastic theory. In addition, the inhomogeneity of medium enhances the nonlocal effect. The conclusions obtained can be applied to the design and dynamic response evaluation of composite nanostructures.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.12
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• pp.2333-2338
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• 2011

In this paper, we develope a wavelet transform based time-frequency domain reflectometry (WTFDR) for the fault localization of underground power cable. The conventional TFDR (CTFDR) is more accurate than other reflectometries to localize the cable fault. However, the CTFDR has some weak points such as long computation time and hard implementation because of the nonlinearity of the Wigner-Ville distribution used in the CTFDR. To solve the problem, we use the complex wavelet transform (CWT) because the CWT has the linearity and the reference signal in the TFDR has a complex form. To confirm the effectiveness and accuracy of the proposed method, the actual experiments are carried out for various fault types of the underground power cable.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.22 no.2
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• pp.408-415
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• 1998

The analysis model is the power law creep material containing an elliptical rigid inclusion subjected to the arbitrarily directional stress on infinite boudary. The stress analysis is performed using the conformal mapping function and complex pseudo-stress function. The stress distributions near an elliptical rigid inclusion are obtained with various ellipse shapes, strain hardening exponents and directions of applied stress.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.48 no.6
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• pp.671-677
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• 1999

In this paper, we have designed power system stabilizer (PSS) using object-oriented method. There are several types of power system stabilizer. A proportional-integral(PI) controller is very simple for practical implementation. Therefore it has been widely employed by the industry. The methods of obtaining the gains(Ki,Kp) of PI controller are root-locus method and sub-optimal regulator approach. But these methods are cannot be applicable to nonlinear system and faulted power system. So we proposed a new method which can be applied to nonlinear system by numerical analysis method. The method of dynamic system simulation by numerical method is very difficult and complex. We proposed flexible simultaion method for complex power system analysis using object-oriented programming(OOP) and applied to PI controller design.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.149-157
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• 2004

We have calculated the power extraction efficiency and the lasing wavelength distribution of complex-coupled(CC) DFB lasers above threshold for various｜$\chi$L｜ and facet reflectivity combinations, and we have compared the results with those at threshold. Also, we have investigated the effect of coupling coefficient ratio(CR) and the reflectivity of AR facet on the power extraction efficiency and the lasing wavelength distribution. At threshold, the single mode yield as a function of power extraction efficiency of in-phase(IP) CC DFB lasers is the same as that of anti-phase(AP) CC DFB lasers. Above threshold, however, the single mode yield as a function of power extraction efficiency of IP CC DFB lasers is much larger than that of AP CC DFB lasers. For IP CC DFB lasers, AR-HR combination has high single mode yield and large power extraction efficiency compared to other facet combinations. IP CC DFB laser with AR-HR combination for ｜$\chi$L｜of 0.8 has the highest single mode yield and largest power extraction efficiency above threshold among the cases considered. For AR-HR combination, as CR increases and the reflectivity of AR facet decreases, both single mode yield and power extraction efficiency increase due to the reduction of the spatial hole burning effect. For AR-HR combination, the lasing wavelength of CC DFB laser has distributed over the stopband of DFB. As CR increases, the lasing wavelength concentrates on the long wavelength side for IP CC DFB laser, while on the short wavelength side for AP CC DFB laser. As ｜$\chi$L｜ increases, the width of the wavelength distribution decreases and the lasing wavelength moves to the long wavelength side.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.1036-1041
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• 1998

A novel ZCS high frequency inverter in complex resonance applied for reduction of PM is developed. This inverter is suppressed the switching stress by using complex resonance. The stable operation is realized by ZCS using overlapping commutation phenomenon. The ZCS characteristics are investigated based on numerical analysis and experimental results.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.41-46
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• 2017

The three neighbors of Korean peninsula, Japan, China, Russia are leading countries of the world as national power and economic power. They are also leading the field of science, particularly top class in the space development. In comparison, our country, Korea, has been going on develop new launch vehicle and building new launch complex in accordance with national space program. In this paper, examining the technical trends of launch complex of Russia and China which based on Russian rocket technologies and it will make a reference for KSLV-II and future space program through this information.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.928-933
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• 2001

Perdeuterated hexaflouroacetylacetonato-ytterbium [Yb(SOL-D)$_3$] complexes are synthesized by the keto-enol tautomerism reaction of Yb(SOL-H)$_3$ in methanol-d$_4$ in order to reduce the radiationless transition to the ligands for the high power solid state laser material. The luminescence properties of Yb(SOL-D)$_3$ complex are measured in the following anhydrous deuterated organic solvents ; Methanol-d$_4$, THF-d$_{8}$, PO(O$CH_3$)$_3$ and DMSO-d$_{6}$. The Luminescence intensity, lifetime and quantum efficiency in DMSO-d$_{6}$ are superior to those in other deuterated solvents. It is suggested that the anhydrous DMSO-d$_{6}$ might be the most appropriate solvent for the laser material of Yb(SOL-D)$_3$ complex.complex.