• Structural Engineering and Mechanics
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• v.13 no.3
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• pp.329-343
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• 2002

In this research, the dynamic stability of an orthotropic elastic conical shell, with elasticity moduli and density varying in the thickness direction, subject to a uniform external pressure which is a power function of time, has been studied. After giving the fundamental relations, the dynamic stability and compatibility equations of a nonhomogeneous elastic orthotropic conical shell, subject to a uniform external pressure, have been derived. Applying Galerkin's method, these equations have been transformed to a pair of time dependent differential equations with variable coefficients. These differential equations are solved using the method given by Sachenkov and Baktieva (1978). Thus, general formulas have been obtained for the dynamic and static critical external pressures and the pertinent wave numbers, critical time, critical pressure impulse and dynamic factor. Finally, carrying out some computations, the effects of the nonhomogeneity, the loading speed, the variation of the semi-vertex angle and the power of time in the external pressure expression on the critical parameters have been studied.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.438-440
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• 1997

This paper proposed a partial resonant switching three-phase high power factor converter using a $PRS^2$(Partial Resonant Soft Switch). The proposed converter has a merit of simple controlled circuit because the input current control DCM(Discontinuous Conduction Mode). And it is improve to input power factor that the snubber capacitor's energy regenerate to the AC source side. This topology is reduced a current/voltage stresses of resonant devices in addition to a partial resonant strategy. The result of simulations with the proposed topology included in this paper.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1202-1205
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• 2000

Germicidal lamps efficiently emit a large amount of ultraviolet rays 253.7nm which have excellent germicidal effect. The lamps are primarily useful for sterilization of air, the surface of various materials and water or liquid. In this paper, analysis of the charge pump power factor correction inverter for driving a 65W UV lamp and electrical characteristics of the lamp are discussed. The operation of the inverter circuit. in which the lamp is included as a load, is analyzed. Experimental results of the inverter circuit are also presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.8
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• pp.15-20
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• 2010

This paper shows a reasonable diversity factor, that was made by the systematic and statistical way considering actual conditions, such as investigated contract power and peak power for the last 5 years of each customer for 20 Lease Apartment. In this paper, it is necessary to analyze the key features and general trend from the investigated data. It made an analysis of the feature parameters, such as average, standard deviation, median, maximum, minimun and thus it was carried out by the linear and nonlinear regression analysis. The standards of demand, diversity, and load density are necessary to create the design of a transformer capacity that is seldom presented in terms for academic study.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.9
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• pp.142-149
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• 2010

Interest in energy efficiency and savings have been rising internationally. For this reason, the domestic housing construction in the area of power equipment is being actively studied. Currently approximately 400,000 per year of domestic housing is being built. Applies to housing construction during the current transformer capacity low utilization and load factor has been applied has been designed. In other words, excessively high reserve capacity has been applied. According to this problem, initial facility costs and power losses will cause because transformer low utilization be appropriated. Thus, the energy efficiency drops. In this paper, analysis of past utilization of the housing transformer, and applying an appropriate demand factor has been analyzing the energy loss reduction. this analysis of current domestic conditions for the proper housing transformer scheme is to calculate the capacity.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.8
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• pp.836-846
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• 1990

This paper presents a Static Var Compensator (SVC) system compensating the reactive power for power system, which consists of a voltage type Pulse Width Modulation (PWM) converter and a reactance linking the converter to the source. The system drives the four quadrant modes. The system determines the magnitude of the input voltage, and then compares it with the magnitude of the source voltage by regulating the phase of the SVC about the source. Therefore, the system generates leading compensation currents when the input voltage is larger than the source in magnitude, and lagging compensation currents for smaller input voltage. Reactive power about voluntary load in power system is smoothly compensated by those compensation currents, and also power factor of source is improved. Furthermore, the SVC system using PWM method may improve the source current waveforms by eliminating the 5th and 7th harmonic components from the input voltages.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.846-848
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• 2005

Midnight electrical power appliance has come into a wide use due to the midnight power rate system introduced for effective power operation and an improved load factor. However, the sharply increased number of the appliance has brought about a serious problem in midnight power supply for the past few years. Moreover, the automatic control device, developed to address the problem, has not properly functioned because of the misusage and illegal conversion of the device. This paper will suggest solutions to the problem by improving the automatic control system for supply time (ACST) and demonstrate its effectiveness through tests.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.2
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• pp.76-84
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• 2006

Interstate electric power system, as an alternative for energy cooperation under regional economic block, has been hotly debated before progressing the restructure in electric power industry and rapidly expanded in many regions after 1990s. Especially, since northeast asia has strong supplementation in resource, load shape, fuel mix etc., interconnection of electric power systems in this region may bring considerable economic benefits. This paper implements a mathematical optimization model, ORIRES, proposed by Russia, in analysing the economic feasibility of system interconnection. Additional analyses on the environmental impact of the system interconnection, and sensitivity of key factor inputs have been performed.

• Journal of the Korean Society of Industry Convergence
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• v.9 no.2
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• pp.133-139
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• 2006

Harmonics happened due to nonlinear systems such as UPS, SCR controlled motors, and fluorescent lighting in distribute power system is very important subject to optimal operation and control of power system. Harmonics sometimes make incorrect operation of protective relaying system under normal condition on power system. In this study, total harmonics distortion(THD) of power were measured and analyzed by the field test on electrical facilities which were installed at the rural industrial complex in Chungbuk province. In addition, the deprivation of power factor by harmonics and the content of THD which is measured at neutral line was researched.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.701-708
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• 1998

This paper presents a novel non-resonant PWM DC-DC converter for X-ray high-voltage power generator using the parasitic impedances of the high-voltage high-frequency link transformer with its output high-voltage control scheme and steady-state characteristics compared to the conventional series-parallel resonant DC-DC converter. The key point of this approach is to evaluate effectiveness of reduction of the turn ratio of the high-voltage high-frequency transformer on improvements in power conversion efficiency and the power factor applying a boost AC-DC converter as DC voltage source, especially in the long exposure term and light output load ranges.