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

• Journal of Power Electronics
• /
• v.18 no.4
• /
• pp.1037-1050
• /
• 2018

This paper presents a novel reconfigurable selective harmonic elimination technique to control harmonics over a wide range of Modulation Indexes (MI) in Multi-Level Inverter (MLI). In the proposed method, the region of the MI is divided into various sectors and expressions are formulated with different switching patterns for each of the sectors. A memetic BBO-MAS (Biogeography Based Optimization - Mesh Adaptive direct Search) optimization algorithm is proposed for solving the Selective Harmonic Elimination - Pulse Width Modulation (SHE-PWM) technique. An experimental prototype is developed using a Field Programmable Gate Array (FPGA) and their FFT spectrums are analyzed over a wide range of MI using a fluke power logger. Simulation and experimental results have validated the performance of the proposed optimization algorithms and the reconfigurable SHE-PWM technique. Further, the sensitivity of the harmonics has been analyzed considering non-integer variations in the magnitude of the input DC sources.

• Journal of Power Electronics
• /
• v.18 no.6
• /
• pp.1650-1658
• /
• 2018

Multilevel converters are being widely used in medium-voltage high-power applications including motor drive systems, utility power transmission, and distribution systems. Selective harmonic elimination (SHE) is a well-known modulation method to generate high quality output voltage waveforms. This paper presents a new simple practical method for generating a generalized five-level waveform without selected low order harmonics. This method is based on a phase-shifted expression for the SHE problem, which can analytically calculate the exact values of switching angles and the feasible modulation index range for three-level and five-level waveforms. The proposed method automatically determines the number of transitions between levels and generates proper output waveform without solving complex trigonometric equations. Due to the simplicity of the computational burden, the real-time implementation of the proposed algorithm can be performed by a simple processor. Simulation and experiment results verify the correctness and effectiveness of the proposed method.

• The Journal of Fisheries Business Administration
• /
• v.49 no.2
• /
• pp.37-48
• /
• 2018

This study analyzed the impact of FTA tariff elimination on the export prices for Norwegian fresh and chilled salmon, of which Korean import has significantly increased since the Korea-EFTA FTA implementation. Korea's fresh and chilled salmon market is almost monopolized by Norway, and Korea's price level is higher than other countries, so it is highly likely that price discrimination occurs. This study theoretically explained that exporters could adjust their prices by market power when tariffs are eliminated in imperfectly competitive markets. And the empirical analysis provided evidence that the exporters have made price adjustments since the FTA took effect, and similar results were found in the relative price comparison with trade statistics and Nasdaq Salmon Index. Therefore, in order to increase consumer welfare in Korean salmon market, it is required to transform the monopolistic market structure into a competitive one.

• Journal of Pharmaceutical Investigation
• /
• v.24 no.4
• /
• pp.217-225
• /
• 1994

With the purpose of improving the therapeutic index of $[^3H]$ acyclovir (ACV) in the treatment of chronic hepatitis B infection, asialofetuin (AF) which after selective interaction with Ashwell's receptor specifically enters into hepatocytes, was chosen as a carrier system for hepatic targeting. This drug was first converted to its monophosphate (ACVMP), which was subsequently activated by water soluble carbodiimide to conjugate with ${\varepsilon}-NH_2$ groups of Iysine residues of AF. The molar ratio of ACVMP to AF in the conjugate was 3.9. In rats, elimination of ACVMP-AF conjugate after i.v. injection showed two phase elimination kinetics. Initial apparent elimination rate constant in rats was $0.191\;min^{-1}$ which was greater than that of ACV. The elimination rate constant from terminal phase was $0.021\;min^{-1}$. Area under the total radioactivities versus time curve was found to be several times larger in liver than in other organs (spleen, intestine, lung and kidney) after i.v. administration of the conjugate labelled in the drug moiety. The above results suggested that ACVMP-AF conjugate was rapidly taken up by hepatocytes and could be a useful hepatic targeting system.

• Journal of Power Electronics
• /
• v.11 no.2
• /
• pp.132-139
• /
• 2011

The selective harmonic elimination pulse width modulation (SHEPWM) switching strategy has been applied to multilevel inverters to remove low harmonics. Naturally, the related equations do not have feasible solutions for some operating points associated with the modulation index (M). However, with these infeasible points, minimizing instead of eliminating harmonics is performed. Thus, harmful harmonics such as the $5^{th}$ harmonic still remains in the output waveform. Therefore, it is proposed in this paper to ignore solving the equation associated with the highest order harmonics. A reduction in the eliminated harmonics results in an increase in the degrees of freedom. As a result, the lower order harmonics are eliminated in more operating points. A 9-level inverter is chosen as a case study. The genetic algorithm (GA) for optimization purposes is used. Simulation results verify the proposed method.

• Journal of Korean Academy of Nursing
• /
• v.7 no.2
• /
• pp.11-21
• /
• 1977

Many in nursing look back on Nursing Research history and proudly point to the fact that emphasis in nursing research has changed from studying the nurse to studying nursing practice. In recent years, much emphasis has been placed on seeking a method of evaluating the quality of nursing care. In spite of these attempts, however, an instrument for evaluating the quality of nursing care that is actually applicable in the clinical area has not been found. The Purposes of this study are as follows: 1) To develop the instrument to be used in evaluating the quality of nursing care provided in the Neuro - Surgery Constant Care Unit of Severance Hospital 2) To evaluate the quality of nursing care in the clinical area. 3) To provide the necessary information for improvement of quality of nursing care. The instrument for evaluating the quality of nursing care, developed by the investigator, was composed of 7 nursing goals and divided into 65 standards of nursing performance. The 7 nursing goal are as follows : 1) Maintenance of airway 2) Maintenance of fluid at electrolyte balance 3) Maintenance of elimination 4) Personal hygiene 5) Optimum activity 6) Prevention of accidents 7) Emotional care The study population defined was composed of all the case (51) who were admitted in the Neuro- Surgery Constant Care Unit of Severance Hospital from May 7-13, 1976. The observation method was used and the data was subjected to the %, X²-test, T-test, F-test and Correlation. The results of tile study were as follows : 1. Levels of nursing performance regarding nursing goals. Seven different nursing care indices were constructed in terms of nursing goals. The index scores were grouped arbitrarily into ,j categories such as "excellent", "good", "moderate", "incomplete", and "poor"based upon the investigator′s personal judgement. a. The nursing index of maintaining airway showed that 78% of the patients fell within the "excellent" and 22% of the patients, fell within the "good" category. b. The nursing index of maintaining fluid & electrolyte balance showed that 95% of the patients fell within the "excellent" and 5 % of the patients fell within the "good" category. c. The nursing index of maintaining elimination showed that 100% of the patients fell within the "excellent" category. d. The nursing index of personal hygiene revealed that 49% of the patients fell within the "excellent" and 51% of the patients fell within the "good" category. e. The nursing index of optimum activity showed that 63% of the patients fell within the "excellent" and 32% of the patients fell within tile "good" and 5% of patients fell within the "moderate" category. f. The nursing index of prevention of accidents showed that 100% of the patients foil within the "excellent" category. g. The nursing index of emotional cart revealed that 27% of the patients fell within the "excellent", 24 % of the patients fell within tile "good", 29 % of the patients fell within the "incomplete" category. From these findings it is disclosed that the quality of nursing care provided in the Neuro- Surgery Constant Care Unit of Severance Hospital was excellent. h. There were statistically significant differences between the nursing index of physical care and emotional care. (t=8.73, D. F. =100. p<0.01) It is revealed that more physical care then emotional care was carried out by nurses. 2. Levels of nursing performance regarding general characteristics of the patients. No significant differences were observed statistically with the nursing indices of nursing goals according to the sex (t=0.084, D. F. =12, p>0.05). Age (F=0.1251, D. F. : 3.18. p 〉0.05), absence or presence of operating experiences (t=0.6032, D. F. =12, p〉0.05, levels of consciousness (F=0.31, D. F. :3. 18, p >0.05) 3. Relationship between the levels of consciousness and the nursing index of each nursing goal. There was negative correlation between the levels of consciousness and the nursing index of maintaining airway (r=-0. 5449, p<0.01) and personal hygiene (r= -0.4075, p<0.01) There was positive correlation between the levels of consciousness and the nursing index of optimum activity (r=0.3936, p <0.01) and emotional care (r=0.7819, p〈0.01). There was slight correlation between the levels of consciousness and the nursing index of maintaining fluid & electrolyte balance (r=-0.3418, 0.010.05) and preventing accidents (r=0.1441, p>0.05.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.3 no.3
• /
• pp.305-311
• /
• 2014

In this paper, a new switching pattern is presented for multilevel inverters. With changing off-angel of each switch, the on time interval of all switches will approximately be equal and then the lifetime of inverter will increase, also using this method can reduce electrical stress on switches in higher levels of inverter. Switching angels as for desired modulation index are calculated using genetic algorithm whereas selective harmonics are controlled within the allowable range. The computed angels are simulated in Matlab/Simulink for respective circuits to validate the results.

• Biomolecules & Therapeutics
• /
• v.14 no.1
• /
• pp.45-49
• /
• 2006

The purpose of this study was to clarify the efflux transport system of choline from brain to blood across the blood-brain barrier (BBB) in rats using the brain efflux index (BEI) method. $[^3H]$Choline was micro-injected into parietal cortex area 2 (Par2) of the rat brain, and was eliminated from the brain with elimination halflife of 45 min. The BBB efflux clearance of $[^3H]$choline was about 124 mL/min/g brain, which was determined from combination of an elimination rate constant $(1.54X10^{-2}min^{-1})$ and the distribution volume in the brain (8.05 mL/g brain). The efflux of $[^3H]$choline was inhibited by unlabeled choline in a dose-dependent manner and was significantly inhibited by cationic substrates, such as hemicholinium-3 and tetraethylammonium (TEA). These results suggest that the BBB may act as an efflux pump for choline to reduce the excessive choline concentration in the brain interstitial fluid.

• Journal of international Conference on Electrical Machines and Systems
• /
• v.1 no.1
• /
• pp.77-83
• /
• 2012

In this paper, an optimal solution to the harmonic reduction problem in a cascaded multilevel inverter with non-equal DC sources using a genetic algorithm (GA) is presented. Switching angles are generated for different values of modulation index by the proposed algorithm, considering minimum voltage total harmonic distortion (THD) whereas selected harmonics are controlled within the allowable limits at all desired modulation indices including the point of discontinuity. Results are stored as a look-up table to be used to control the inverter for a certain operating point. The computed angles are used in a simulated circuit in Matlab\Simulink to validate the results.