• Journal of Power Electronics
• /
• v.18 no.4
• /
• pp.1027-1036
• /
• 2018

In this paper a new generalized space vector pulse width modulation scheme is proposed based on the principle of reverse mapping to drive the switches of multilevel inverters. This projected scheme is developed based on the middle vector of the subhexagon which holds the tip of the reference vector, which plays a major role in mapping the reference vector. A new approach is offered to produce middle vector of the subhexagon which holds tip of the reference vector in the multilevel space vector plane. By using middle vector of the subhexagon, reference vector is linked towards the inner two level sub-hexagon. Then switching vectors, switching sequence and dwell times corresponding to a particular sector of a two-level inverter are determined. After that, by using the two level stage findings, the switching vectors related to exact position of the reference vector are directly generated based on principle of the reverse mapping approach and do not need to be found at n level stage. In the reverse mapping principle, the middle vector of subhexagon is added to the formerly found two level switching vectors. The proposed generalized algorithm is efficient and it can be applied to an inverter of any level. In this paper, the proposed scheme is explained for a five-level inverter and the performance is analyzed for five level and three level inverters through MATLAB. The simulation results are validated by implementing the propose scheme on a V/f controlled three-level inverter fed induction motor using dSPACE control desk.

• The Korean Journal of Pain
• /
• v.22 no.3
• /
• pp.199-205
• /
• 2009

Background: A major ingredient of green tea is epigallocatechin-3-gallate (EGCG), and this is known to have many beneficial effects for cancer prevention and also on the cardiovascular system and neurodegenerative diseases through its anti-oxidant, anti-angiogenic, anti-inflammatory, lipid-lowering and neuroprotective properties. Its actions on nociception and the spinal nervous system have been examined in only a few studies, and in these studies EGCG showed an antinociceptive effect on inflammatory and neuropathic pain, and a neuroprotective effect in motor neuron disease. This study was performed to investigate the effect of EGCG on acute thermal pain and the development of morphine tolerance at the spinal level. Methods: The experimental subjects were male Sprague-Dawley rats and the Hot-Box test was employed. A single or double-lumen intrathecal catheter was implanted at the lumbar enlargement for drug administration. An osmotic pump was used to infuse morphine for 7 days for induction of morphine tolerance. EGCG was injected repeatedly for 7 days at twice a day through the intrathecal catheter. Results: Intrathecal EGCG increased the paw withdrawal latency (PWL) after repeated administration for 7 days at twice a day, but this did not happen with administering on single bolus injection of EGCG. In addition, the antinociceptive effect of intrathecal morphine was not affected by co-administration with EGCG. A continuous 7-day infusion of morphine caused a significant decrease of the PWL in the control group (M + S, morphine plus saline). In contrast, intrathecal EGCG injection over 7 days blocked the decrease of the PWL in the experiment group (M + E, morphine plus EGCG). Conclusions: Intrathecal ECGC produced a weak antinociceptive effect for acute thermal pain, but it did not change the morphine's analgesic effect. However, the development of antinociceptive tolerance to morphine was attenuated by administering intrathecal EGCG.

• Journal of Physiology & Pathology in Korean Medicine
• /
• v.19 no.6
• /
• pp.1666-1672
• /
• 2005

Oriental medicinal drugs have a broad spectrum of clinical use for the cure of nervous system diseases including brain ischemic damages or neuropathies. Yet, specific drugs or drug components used in the oriental medicine in relation to none fiber regeneration are not known. In the present study, possible growth promoting effects of oriental medicinal drugs were investigated in the injured sciatic nerve system in the rat. By immunofluorescence staining, we found that Jahageo (JHG, Hominis placenta) increased Induction levels of axonal growth associated protein GAP-43 in the rat sciatic none. Small growth promoting activity was found in Golsebo (GSB, Drynariae rhizoma) and Baikhasuo (BHSO, Polygoni multiflori radix) drugs. JHG also increased cell cycle protein Cdc2 levels in the injured area of the sciatic nerves. Immunofluorescence staining indicated that induced Cdc2 protein was mostly localized in the Schwann cells in the injury area, implying that JHG activity might be related to increased Schwann cell proliferation during axonal regeneration. Moreover, levels of phospho-extracellular signal-regulated (ERK) pathway in the injured neNes were elevated by JHG treatment while levels of total ERK were unaltered. In vivo measurement of axonal regeneration using retrograde tracer showed that JHG, GSB and BHSO significantly enhanced Dil-labeled regenerating motor neurons compared with saline control. The present data suggest that oriental medicinal drugs such as JHG, GSB, and BHSO may be a useful target for developing specific drugs of axonal regeneration.

• Journal of the Korean Society for Railway
• /
• v.11 no.5
• /
• pp.477-481
• /
• 2008

This paper dealt with a detection method of series arc existence which is a symptom of electric fires in low-voltage system. The proposed detection circuit consists of a high-pass filter with a low cut-off frequency of 3kHz to attenuate power frequency voltage by 80 dB and an active band-pass filter with a center frequency of 4kHz to detect only the series arc signals. The performance of the circuit was evaluated in a phase-controlled incandescent lamp as a non-linear load and an inverted-fed induction motor as a high frequency load by using the arc generator specified in UL1699. From the experimental results, it was confirmed that the proposed method solved the detection error, which is being the most problem, by discriminating the series arc signal even in non-linear and high frequency loads.

• Journal of Korean Society of Transportation
• /
• v.19 no.4
• /
• pp.35-47
• /
• 2001

Traffic represents one of the largest sources of primary air pollutants in urban area. As a consequence. numerous abatement strategies are being pursued to decrease the ambient concentration of pollutants. A characteristic of most of the these strategies is a requirement for accurate data on both the quantity and spatial distribution of emissions to air in the form of an atmospheric emission inventory database. In the case of traffic pollution, such an inventory must be compiled using activity statistics and emission factors for vehicle types. The majority of inventories are compiled using passive data from either surveys or transportation models and by their very nature tend to be out-of-date by the time they are compiled. The study of current trends are towards integrating urban traffic control systems and assessments of the environmental effects of motor vehicles. In this study, a methodology of motor vehicle emission calculation by using real-time traffic data was studied. A methodology for estimating emissions of CO at a test area in Seoul. Traffic data, which are required on a street-by-street basis, is obtained from induction loops of traffic control system. It was calculated speed-related mass of CO emission from traffic tail pipe of data from traffic system, and parameters are considered, volume, composition, average velocity, link length. And, the result was compared with that of a method of emission calculation by VKT(Vehicle Kilometer Travelled) of vehicles of category.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.131-138
• /
• 2018

In this study, we investigated the trend of technological development in major countries related to the propulsion equipment of railway vehicles. The propulsion system is the main equipment of electric vehicles. A lot of time and investment are required in order to ensure the development of technology. Therefore, developed countries have maximized their effort to develop technologies with safety, reliability, and convenience of maintenance. They have also done their utmost to prevent technology transfer to other countries after the development of new technologies. For example, Toshiba of Japan developed a new 3,300V/1,500 A class IGBT power device, but was reluctant to export it to foreign countries in order to protect this technology. In this study, we analyzed the patents applied for related to propulsion control systems and presented the direction of development during the technical development of these systems. The patent analysis of the core technologies was conducted using the Thomson Innovation DB. We examined the number of patents applied for by country, year and major applicant. As a result of the analysis, it was found that the proportion of patent applications per country was in the order of China, 48%, Europe 16.6%, and the United States 14.9%. The patent situation of the top 10 principal applicants revealed that (the top three were?) ABB 14%, GE 13%, and CRRC 12%. At the same time, we also conducted a qualitative analysis of the level of technical development by evaluating such factors as the influence index, quotation, market securing power and citation. Based on the result of the patent analysis, we presented the direction of technical development of the propulsion control equipment of railway vehicles. Based on the analysis results, it was found that domestic applicants considerably reduced their efforts to protect their patents from foreign companies. Nowadays, most of the electric motors used in Korea are induction motors. In advanced countries, permanent magnet electric motors are employed in new railway lines. Therefore, intensive investment is needed in new developments.