• Journal of Electrical Engineering and Technology
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• v.10 no.1
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• pp.261-270
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• 2015

In this paper, the Optimal Harmonic Stepped Waveform (OHSW) method is proposed in order to eliminate the selective harmonic orders available at the output of cascaded multilevel inverter (CMLI) fed by solar photovoltaic (SPV). This technique is used to solve the harmonic elimination equations based on stepped waveform analysis in order to obtain the optimal switching angles which in turn reduce the Total Harmonic Distortion (THD). The OHSW method considers the output voltage waveform as four equal symmetries in each half cycle. In the proposed method, a solar fed fifteen level cascaded multilevel is considered where the magnitude of six numbers of harmonic orders is reduced. A programmable pulse generator is developed to carry the switching angles directly to the semiconductor switches obtained as a result of OHSW analysis. Simulations are carried out in MATLAB/Simulink in which a separate model is developed for solar photovoltaic which serves as the input for cascaded multilevel inverter. A 3kWp solar plant with multilevel inverter system is implemented in hardware to show the effectiveness of the proposed system. Based on the observation the OHSW method provides the reduced THD thereby improving power quality in renewable energy applications.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1244-1255
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• 2017

The space vector pulse width modulation (SVPWM) technique is a popular PWM method for medium voltage drive applications. Conventional SVPWM (CSVPWM) and bus clamped SVPWM (BCSVPWM) are the most common SVPWM techniques. This paper evaluates the performance of various advanced BCSVPWM strategies in terms of their harmonic distortion and switching loss based on a uniform frame work. A uniform frame work, pulse number captures the performance parameter variations of different SVPWM strategies for various number of samples with heterogeneous pulse numbers. This work compares different advanced BCSVPWM techniques based on the modulation index and location of the clamping position (zero vector changing angle ) of a phase in a line cycle. The frame work provides a fixed fundamental frequency of 50Hz. The different BCSVPWM switching strategies are implemented and compared experimentally on a 415V, 2.2kW, 50Hz, 3-phase induction motor drive which is fed from an IGBT based 2 KVA voltage source inverter (VSI) with a DC bus voltage of 400 V. A low cost PIC microcontroller (PIC18F452) is used as the controller platform.

• IMMUNE NETWORK
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• v.13 no.1
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• pp.10-15
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• 2013

Aluminum hydroxide (alum) is the most widely used adjuvant in human vaccines. Nevertheless, it is virtually unknown whether alum acts on B cells. In the present study, we explored the direct effect of alum on Ig expression by murine B cells in vitro. LPS-activated mouse spleen B cells were cultured with alum, and the level of isotype-specific Ig secretion, IgG1 secreting cell numbers, and Ig germ-line transcripts (GLT) were measured using ELISA, ELISPOT, and RT-PCR, respectively. Alum consistently enhanced total IgG1 production, numbers of IgG1 secreting cells, and $GLT{\gamma}1$ expression. These results demonstrate that alum can directly cause IgG1 isotype switching leading to IgG1 production.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.12
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• pp.162-168
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• 2009

This paper describes a study that is to redesign insulation of transmission lines and determine required the numbers of insulators in order to enhance the insulation performance of existing transmission lines which were constructed with standard insulation design, considering overvoltage analysis results, probabilities and characteristics of faults. To ensure proper insulation distance without deteriorating the required performance, EMTP model is established to calculate maximum overvoltage in the line. The fault records and predicted outage rates due to lightning and contamination in the line were investigated and analyzed respectively. It presents a method to determine the numbers of insulators considering the probability and the characteristic of fault.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.199-204
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• 2007

This paper presents design of interleave configured dc-dc converter for high power distributed power system applications. The multi channel interleaving buck converter with small inductance has proved to be suitable for micro-grid, requiring medium output voltages, high output currents and fast transient response. Integrated magnetic components are used to reduce the size of the converter and improve efficiency. Unlike conventional methods, the distributed approach requires no centralized control, automatically accommodates varying numbers of converter cells, and is highly tolerant of subsystem failures. A general methodology for achieving distributed interleaving is proposed, along with a specific implementation approach. The design and simulation verification of switching frequency 10 kHz system is presented with interleaved clocking of the converter cells. The simulation (simulated by PSIM 6.1) results corroborate the analytical predictions and demonstrate the tremendous benefits of the distributed interleaving approach.

• East Asian mathematical journal
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• v.32 no.2
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• pp.217-232
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• 2016

The purpose of this study is to investigate the assessment expertise of Mathematics' teachers, focusing on the competence in designing assessment item development. In this present research, I analysed how the teachers' competence appears in designing assessment items development when they generated problems the given problem into a new one. To examine this assumption, the following research questions were posed and investigated in the present study : How do Pre-service and In-service Teachers in primary schools develop the assessment item when generating problems the given problems into new problems? The result from the case study of metamorphosing the given problem into a new problem teachers used similar patterns switching numbers or changing units in order to develop new problems. Also, teachers in primary schools tend to develop problems as commonly as in the mathematics workbooks. In-service teachers tend to have better skills developing assessment items, but there were quite much of variability between individuals.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.15-17
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• 1998

The position of LPM's mover can be estimated by the equivalent inductance variation with the mover's displacement. Hence, in this paper, we obtained the position detection signal by the calculation of equivalent inductance variation using the winding of linear pulse motor. And the various parameters for calculation of equivalent inductance variation were obtained by the design specification and finite element analysis of linear pulse motor. With this position signal, it is possible to calculate the driving numbers of steps, to confirm the state of step out and to determine the optimal switching angle, etc.

• Korean Journal of Microbiology
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• v.16 no.3
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• pp.131-139
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• 1978

Mycoplasma pneumoniae was examined for growth characteristics and morphology when cultivated in several media supplemented with a variety of sera and under different atmospheric conditions. different formula of the medium as well as different sources of lot numbers of the serum in the same medium exhibited varying effects on growth rate and adherence. When the organisms were cultivated in SSR-2 medium in a normal atmospheric environment or under a facultative anaerobic condition provided with carbon dioxide, they developed filamentous cells with heavy growth, whereas mainly round-shaped cells were produced under strict anaerobic conditions of hydrogen and carbon dioxide. Both morphologies of the organism were transformed by switching the incubation environments. An inverted phasecontrast microscopy using modified petri dishes was excellent to observe single cells and useful to follow the development of the cells. Growth, turbidity, and pneumoniae colonies developed on a solid medium and produced clear when overlaid with sheep blood agar.

• Journal of the Korean Magnetics Society
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• v.12 no.3
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• pp.109-116
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• 2002

We designed the flyback planar transformer, which had 8 W capacity, with 70 V input voltage and 8.2 V output voltage for the establishment of design method and the confirmation of application possibility. The numerical value of inductance measured under the switching frequency of 120 kHz was 1650 $\mu$H, which was the inductance efficiency of'85∼87% against theoretical value. The A.C. resistance of primary and secondary coil was 4.2 Ω and 0.25 Ω respectively, On the other hand, the quality factor for each wound numbers showed quite a high value of 158 and 75 respectively. And the Coupling Factor was 0.96∼0.97 under 120 kHz switching frequency. The inductance rapidly increased as the thickness of the core plane increased until it became 1.4 mm but under the thickness more than 1.4 mm, there was no substantial change. Therefore, the critical value of the plane thickness of core was 1.4 mm. And the shape of the output wave of the planar transformer at 70V input voltage was a stable square wave.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.12
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• pp.71-78
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• 2008

The paper proposes a chaotic double tent mapping PWM scheme for mitigation the acoustic noise of a motor chive. The chaos area ${\lambda}=0.99$ in bifurcation tree of the double tent mapping is used for generating the chaotic numbers. A 80C196 micro-controller is employed for generation of chaotic numbers, and the triangular carrier with chaotic frequency is obtained by using a 80C196 micro-controller and a MAX038 frequency modulator. The experiments are executed with a 1.5[kw] induction motor chive under the 2.5[A] load condition. As results, the experimental results show that the carrier, voltage and 3-D switching noise spectra of the proposed scheme is spread over the chaotic frequency range with no specific frequency concentration. Thereby, the shrill acoustic noise radiated from a motor chive is reduced by the proposed scheme.