• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.300-302
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• 1996

In this paper a new series-parallel compensated uninterruptible power supply is proposed. Its series compensator shapes input current to sinusoid. The power handled by series compensator is only a quarter of ratings. And parallel compensator delivers sinusoidal voltage to nonlinear load. The parallel compensator is backedup with battery. This system has capabilities of power line conditioner and backup power with reduced size.

• Journal of the Korean Data and Information Science Society
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• v.14 no.3
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• pp.461-469
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• 2003

In this paper, we consider the series and parallel system which include two components. We assume that the lifetimes of two components follow the bivariate Pareto model with random censored data. We obtain the estimators and approximated confidence intervals of the reliabilities for series and parallel systems based on maximum likelihood estimator and the relative frequency, respectively. Also we present a numerical example by giving a data set which is generated by computer.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.9 no.14
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• pp.45-48
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• 1986

This paper studies reliability growth model in redundancy allocation of Parallel-series system in which several series system is linked parallelly, The model is generalized by system redundancy of sub-system that have components redundancy. The stage of components in each sub-system is established differently. At the same time by assigned the different number of constraints to the sub-system, this paper deals with rather practical reliability growth model.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.390-395
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• 2005

Sunspots are dark areas that grow and decay on the lowest level of the sun that is visible from the Earth. Shot-term predictions of solar activity are essential to help plan missions and to design satellites that will survive for their useful lifetimes. This paper presents a parallel-structure fuzzy system(PSFS) for prediction of sunspot number time series. The PSFS consists of a multiple number of component fuzzy systems connected in parallel. Each component fuzzy system in the PSFS predicts future data independently based on its past time series data with different embedding dimension and time delay. An embedding dimension determines the number of inputs of each component fuzzy system and a time delay decides the interval of inputs of the time series. According to the embedding dimension and the time delay, the component fuzzy system takes various input-output pairs. The PSFS determines the final predicted value as an average of all the outputs of the component fuzzy systems in order to reduce error accumulation effect.

• Journal of Power Electronics
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• v.15 no.4
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• pp.886-898
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• 2015

The design feasibility of a micro unidirectional DC transmission system based on an input-parallel output-parallel (IPOP) converter is analyzed in this paper. The system consists of two subsystems: an input-parallel output-series (IPOS) subsystem to step up the DC link voltage, and an input-series output-parallel (ISOP) subsystem to step down the output voltage. The two systems are connected through a transmission line. The challenge of the delay caused by the communication in the control system is addressed by introducing a ring communication structure, and its influence on the control system is analyzed to ensure the feasibility and required performance of the converter system under practical circumstances. Simulation and experiment results are presented to verify the effectiveness of the proposed design.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1332-1336
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• 2009

If water-chillers are arranged in series-series counterflow, compressor lift of each chiller will be decreased in comparison with water-chillers in parallel. That means that compressor power of the chillers in series will be lower than that of chillers in parallel. However, the pressure drop of the water flow through the chillers in series will increase, and thus increase the power of water pumps. This disadvantage will be made good by increasing the temperature difference of water flow through evaporator and condenser, but the water flow rates will decrease. This paper explores the optimal parameters in system of series-series counterflow for central chilled water plants such as the leaving chilled water temperature, the leaving condenser water temperature, condenser water flow rate and number of chillers in series.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.201-203
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• 2005

A new 3-phase line-interactive UPS(Uninterruptible Power Supply) system with parallel-series active power-line conditioning capability using AC line reactor and two four-leg PWM VSCs(Voltage Source Converters) was introduced recently, In this paper, the strategy of voltage control in suggested UPS system is explained. The objective of proposed voltage controllers in parallel(shunt) and series PWM VSC is to guarantee satisfactory characteristics in steady state and transient state.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.6
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• pp.12-17
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• 2000

IN induction heating system the high frequency operation allows a rapid response to current fluctuation in the inverter and result in improved welding quality. To work induction heating of nonferrous metals, a welding power supply is need high working frequency and high power. This paper is shown design technique for increasing working frequency in induction heating for welding coppers. A series-parallel resonate inverter consists of H-type bridges, each of whose arms is composed of a combination of two parallel IGBTs. Inverter operating with the fixed frequency is controlled by pulse width modulation (PWM). As switching adapted the Zero-Voltage Switching technique to reduce switching losses the system is high efficiency. The propose inverter has feature which is high efficiency for very wide load variations with a narrow range of duty cycle ratio control and load short circuit capability. Detailed experimental results obtained from a 48[V] output, 500[W] experimental inverter are presented to verify the concept.

• KIEE International Transactions on Power Engineering
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• v.5A no.4
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• pp.378-384
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• 2005

This paper proposes a new series and parallel Sin+Cos PSS (power system stabilizer) for the purpose of improving the existing PSS1A's performance. The purpose of the PSS is to enhance the damping of power system oscillations through injection of auxiliary signals for an excitation control terminal. The proposed series and parallel Sin+Cos PSS is connected adding the Sin+Cos terms additionally with the serial and parallel connection in a conventional PSS1A. The proposed controller is aimed at considering the damping of oscillation when it changes parameter fluctuations or operational load variations in a power system. The electric power system used is the KEPCO system and the voltage of the power transmission line is 154kV and 345kV. The PSCAD/EMTDC package is used to authorize the effect of the proposed controller. Simulations were shown by and compared with the waveforms for frequency, voltage and electric power.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.92-98
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• 2013

There are lots of studies about hybrid electric vehicles (HEVs) because of the global warming and energy problems. Series and parallel HEVs are the common types of many developing hybrid vehicle types. Series HEV uses engine only as the generator for the battery but parallel HEV utilizes engine for driving and generating of the vehicle. In this paper, backward simulations based on dynamic programming were conducted for the fuel economy analysis of two different types of hybrid transit buses depending on driving cycles. It is shown that there is a relation between the type of HEV and the characteristics of driving cycles. Regarding the aggressiveness, the series hybrid bus is more efficient than the parallel system on highly aggressive driving cycle. On the other hand, the parallel hybrid bus is more efficient than the series system on low aggressive driving cycle. Based on this results of the paper, it is expected to choose more efficient type of the hybrid buses according to the driving cycle.