• Journal of Power Electronics
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• v.16 no.6
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• pp.2162-2172
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• 2016

This paper presents a Direct Torque Control (DTC) strategy for the five-phase induction motor driven by a three-level five-phase inverter in order to improve the performance of the five-phase induction motor. In the proposed DTC technique, only 22 voltage vectors out of 243 available voltage vectors in a three-level five-phase inverter are selected and are divided in 10 sectors each with a width of $36^{\circ}$. The four different DTC combinations (DTC-I, II, III and IV) for a three-level five-phase induction motor drive are investigated for improving the performance of five-phase induction motor. All four of the DTC strategies utilize a combination of the same large and zero voltage vectors, but with different medium voltage vectors. Out of these four techniques, DTC-II gives the best performance when compared to the others. This DTC-II technique is analyzed in detail for improvements in the performance of five-phase induction motor in terms of torque ripple, x-y stator flux and Total Harmonics Distortion (THD) of the stator phase current when compared to its two-level counterparts. To verify the effectiveness of the proposed three-level five-phase DTC control strategy, a DSP based experimental system is build. Simulation and experimental results are provided in order to validate the proposed DTC technique.

• Journal of Power Electronics
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• v.14 no.5
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• pp.937-945
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• 2014

This paper presents an optimized space vector pulse-width modulation (OSVPWM) technique for a five-level cascaded H-bridge (CHB) inverter. The space vector diagram of the five-level CHB inverter is optimized by resolving it into inner and outer two-level space vector hexagons. Unlike conventional space vector topology, the proposed technique significantly reduces the involved computational time and efforts without compromising the performance of the five-level CHB inverter. A further optimized (FOSVPWM) technique is also presented in this paper, which significantly reduces the complexity and computational efforts. The developed techniques are verified through MATLAB/SIMULINK. Results are compared with sinusoidal pulse-width modulation (SPWM) to prove the validity of the proposed technique. The proposed simulation system is realized by using an XC3S400 field-programmable gate array from Xilinx, Inc. The experiment results are then presented for verification.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.1180-1186
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• 2007

This paper contains that the current emergency response procedure through the railroad accident type at domestic and foreign, and the response program which is more systematic as a result of improving weaknesses. Because the response program at home is less sufficient than developed country's, we have made an investigation into system of classification in America, British, Germany, Japan for organizing separate emergency response code. we have researched the recognition response of five senses for minimizing the accident damage in a way of spreading the emergency response type analyzed through the accident procedure according to the feature of five senses by the first recognizer. Based on the first recognitions response of five senses, the scenario has been established according to each types and the criteria of accident has been researched through classifying the recognition of five senses response level, early response level, self-response level, outside support level.

• Journal of Power Electronics
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• v.16 no.2
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• pp.498-511
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• 2016

This paper presents a single-phase five-level inverter controlled by two novel pulse width modulation (PWM) switching techniques. The proposed PWM techniques are designed based on minimum switching power loss and minimum total harmonic distortion (THD). In a single-phase five-level inverter employing six switches, the first proposed PWM technique requires four switches to operate at switching frequency and two other switches to operate at line frequency. The second proposed PWM technique requires only two switches to operate at switching frequency and the rest of the switches to operate at line frequency. Compared with conventional PWM techniques for single-phase five-level inverters, the proposed PWM techniques offer high efficiency and low harmonic components in the output voltage. The validity of the proposed PWM switching techniques in controlling single-phase five-level inverters to regulate load voltage is verified experimentally using a 100 V, 500 W laboratory prototype controlled by dspace 1103.

• Journal of Power Electronics
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• v.19 no.1
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• pp.134-145
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• 2019

A single-phase step-up five-level inverter topology with a new phase-shifted pulse width modulation (PS-PWM) strategy is proposed in this paper. When compared with conventional single-phase five-level inverter topologies, the proposed topology can realize multilevel inversion with a double step-up ratio, a reduced number of switching devices and self-balanced capacitor voltages. When compared with the conventional PS-PWM strategy, the new PS-PWM strategy can be implemented with one carrier reduced, which makes it much easier to implement in a digital signal processor (DSP) system. Experimental results have been presented to verify the effectiveness of the proposed inverter and the PS-PWM strategy.

• Journal of The Korean Association For Science Education
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• v.23 no.1
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• pp.47-56
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• 2003

The present study was carried out to analyse the frequency(%) for five kinds of inquiry context elements for six kinds of the high school science textbooks in the 7th curriculum. All the elements was classified into three process achievement level such as the basic, supplementary and further level introduced firstly in the 7th curriculum. Five elements of the inquiry context categories appeared as pure scientific context(61.8%), everyday context(22.2%), natural environmental context(7.7%), techno-industrial context(5.9%), and social context(2.4%) in the basic, supplementary and further level. Social context wasn't appeared in the supplementary level. In five elements of inquiry context, total elements appeared 7,139(85.5%) kfrequencies in the basic level and 691(8.1%) frequencies in the further level. However total elements appeared 529(6.4%) frequencies in the supplementary level. The kinds and frequencies of the elements for the inquiry context suggested in the basic level were more than those in the supplementary and in the further level. The social context was not appeared in the supplementary level. However five inquiry context elements were all appeared in the basic and further level.

• Asia pacific journal of information systems
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• v.6 no.2
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• pp.125-148
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• 1996

This paper is primarily focused on the function of model management systems such as higher level representations and buildings of optimization models using them, especially in the area of the telecommunication network models. This research attempts to provide the model builders an intuitive language-namely higher level representation-using five distinctivenesses : Objective, Node, Link, Topological Constraint including five components, and Decision. The paper elaborates all components included in each of distinctivenesses extracted from structural characteristics of typical telecommunication network models. Higher level representations represented with five distinctivenesses should be converted into base level representations which are employed for semantic representations of linear and integer programming problems in knowledge: assisted optimization modeling system(UNIK-OPT). Furthermore, for formulating the network model using higher level representations, the reasoning process is proposed. A system called UNIK-NET is developed to implement the approach proposed in this research, and the system is illustrated with an example of the network model.

• Korean Security Journal
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• no.8
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• pp.361-377
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• 2004

This study is to examine the relations between the big five critical crime that consist of homicide, robbery, rape, theft, violence and the private security services. To achieve this objective, this research selected the subject of study, specially, 2002 status of the private security such as the number of companies and employees classified by areas along with the big five crime mentioned above classified by area. The research data is secondary data that is from '2003 Crime Analysis' of the Supreme Public Prosecutors' Office and 'The private Security Related Data' of the National Police Agency. The selected data were analyzed according to the variables by using SPSS 10.0 statistics software program. Each hypothesis was verified around the level of significance ${\alpha}$=.05 by using the statistical techniques, such as Descriptive Statistics, Correlation, Regression, etc. The following was the result of the study, First, the total number of the big five crime affects the number of the companies at significant level. Second, the number of the security companies can be explained by the each total number of the big five crime in the order of theft, robbery, violence, rape and murder. Third, the total number of the big five crime affects the number of the security employees at significant level. Forth the number of the security employees can be explained by the each total number of the big five crime in the order of theft, robbery, violence, rape and murder.

• Journal of Power Electronics
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• v.17 no.4
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• pp.914-922
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• 2017

Multilevel converters have attracted a lot of attention in recent years. The efficiency parameters of a multilevel converter such as the switching losses and total harmonic distortion (THD) mainly depend on the modulation strategy used to control the converter. Among all of the modulation techniques, the selective harmonic elimination (SHE) method is particularly suitable for high-power applications due to its low switching frequency and high quality output voltage. This paper proposes a new expression for the SHE problem in five-level converters. Based on this new expression, a simple analytical method is introduced to determine the feasible modulation index intervals and to calculate the exact value of the switching angles. For each selected harmonic, this method presents three-level or five-level waveforms according to the value of the modulation index. Furthermore, a flowchart is proposed for the real-time implementation of this analytical method, which can be performed by a simple processor and without the need of any lookup table. The performance of the proposed algorithm is evaluated with several simulation and experimental results for a single phase five-level diode-clamped inverter.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.3
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• pp.64-69
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• 2001

Energy recovery in the regenerative region is very important when SRM is used in traction drive, This is to reduce en-ergy loss during mechanical braking and/or to have a high efficiency drive during braking To control excitation voltage in motor operation and regenerative voltage in the generator operation in the SRM multi-level voltage control is effective The paper sug-gests multi-level inverter which is useful for motoring and regenerative operation in SRM