• Journal of Power Electronics
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• 제16권4호
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• pp.1245-1255
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• 2016

The single resonant inverter is widely employed in typical inductive power transfer (IPT) systems to generate a high-frequency current in the primary side. However, the power capacity of a single resonant inverter is limited by the constraints of power electronic devices and the relevant cost. Consequently, IPT systems fail to meet high-power application requirements, such as those in rail applications. Total harmonic distortion (THD) may also violate the standard electromagnetic interference requirements with phase shift control under light load conditions. A power regulation approach with selective harmonic elimination is proposed on the basis of a parallel multi-inverter to upgrade the power levels of IPT systems and suppress THD under light load conditions by changing the output voltage pulse width and phase shift angle among parallel multi-inverters. The validity of the proposed control approach is verified by using a 1,412.3 W prototype system, which achieves a maximum transfer efficiency of 90.602%. Output power levels can be dramatically improved with the same semiconductor capacity, and distortion can be effectively suppressed under various load conditions.

• 한국지반신소재학회논문집
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• 제18권4호
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• pp.97-106
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• 2019

본 연구는 오염원 유출을 방지하기 위한 경사식호안 해상폐기물매립장 차수시스템에 요구되는 적절한 기준을 제안하기 위하여 해석을 수행하였다. 차수시스템은 바닥과 측면으로 구성하였다. 바닥차수시스템은 불투수 점토층이 측면차수시스템은 HDPE 차수시트가 주 역할을 하고 부수적으로 중간보호층이 차수를 담당한다. SEEP/W와 CTRAN/W 프로그램을 이용하여 침투·이류 분산 해석을 실시하였다. 해석결과, 바닥차수시스템인 점토층에 대하여 요구되는 투수계수와 두께가 제안되었다. 측면차수시스템인 HDPE 차수시트에 대해서는 설치길이와 중간보호층에 대해서는 요구되는 투수계수가 제안되었다.

• Journal of Power Electronics
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• 제15권6호
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• pp.1508-1516
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• 2015

A single phase H-bridge inverter is employed in conventional Inductive Power Transfer (IPT) systems as the primary side power supply. These systems may not be suitable for some high power applications, due to the constraints of the power electronic devices and the cost. A high-frequency cascaded multi-level inverter employed in IPT systems, which is suitable for high power applications, is presented in this paper. The Phase Shift Pulse Width Modulation (PS-PWM) method is proposed to realize power regulation and selective harmonic elimination. Explicit solutions against phase shift angle and pulse width are given according to the constraints of the selective harmonic elimination equation and the required voltage to avoid solving non-linear transcendental equations. The validity of the proposed control approach is verified by the experimental results obtained with a 2kW prototype system. This approach is expected to be useful for high power IPT applications, and the output power of each H-bridge unit is identical by the proposed approach.

• 대한인간공학회지
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• 제26권4호
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• pp.75-83
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• 2007

Why do some countries walk on the right and others on the left? People have a dominant hand which leads to a natural tendency to favor one side of the road or another depending on the means of transportation being used. The primary objective of this study was to investigate the stereotype of Korean regarding preferred walking direction in encountering various facilities and provide the appropriate information to traffic policy makers. Six hundred Korean male and female subjects aging from 12 to 83 were selected to investigate the various statistics about their preferred walking direction and their employment characteristics on walking diverse facilities. The walking directions of eleven different facilities were asked along with other relative subjects' characteristics(e.g., age, gender, hand and foot dominance) to determine the relationship among these obtained data. The descriptive statistics showed that 73.7% and 26.3% were preferred walking right and left direction respectively. Moreover, various statistical analysis revealed that general tendency of walking direction was varied by hand and foot dominances. There were strong tendency that right-handed people prefer walking right side of the road and vise versa, hence this should be considered in setting up traffic policies. As a concluding remark, it is better to design traffic policies and regulations in the way that peoples' preference and expectation.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.829-841
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• 2018

An experiment was conducted for the OECD/NEA ROSA-2 Project using the large-scale test facility (LSTF), which simulated a 17% hot leg intermediate-break loss-of-coolant accident in a pressurized water reactor (PWR). In the LSTF test, core uncovery started simultaneously with liquid level drop in crossover leg downflow-side before loop seal clearing, and water remaining occurred on the upper core plate in the upper plenum. Results of the uncertainty analysis with RELAP5/MOD3.3 code clarified the influences of the combination of multiple uncertain parameters on peak cladding temperature within the defined uncertain ranges. For studying the scaling problems to extrapolate thermal-hydraulic phenomena observed in scaled-down facilities, an experiment was performed for the OECD/NEA PKL-3 Project with the Primarkreislaufe Versuchsanlage (PKL), as a counterpart to a previous LSTF test. The LSTF test simulated a PWR 1% hot leg small-break loss-of-coolant accident with steam generator secondary-side depressurization as an accident management measure and nitrogen gas inflow. Some discrepancies appeared between the LSTF and PKL test results for the primary pressure, the core collapsed liquid level, and the cladding surface temperature probably due to effects of differences between the LSTF and the PKL in configuration, geometry, and volumetric size.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2005년도 전력전자학술대회 논문집
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• pp.439-441
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• 2005

A new LLC resonant converter with multiple outputs is proposed for high efficiency and low cost plasma display panel (PDP) power module. In the proposed converter, ZVS turn-on of the primary MOSFETs and ZCS nun-off of the secondary diodes are guaranteed in the overall input voltage and output load range. Moreover, the primary MOSFETs and the secondary diodes have low voltage stresses clamped to input and the output voltage, respectively. Therefore, the proposed converter shows the high efficiency due to the minimized switching and conduction losses. In addition, by employing the transformer, which has the two and more secondary side, the proposed converter can have multiple outputs and they show the great cross-regulation characteristics. As a result, the proposed converter can be implemented with low cost and compact size. The 500W prototype is implemented, which integrates the sustaining and addressing power supplies of PDP power module. The maximum efficiency is 96.8% and the respective output voltages are well regulated. Therefore, the proposed converter is suitable for high efficiency and low cost PDP power module.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.1016-1017
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• 2015

본 논문은 최근 에너지 절약의 중요성이 커지면서 많은 관심을 가지고 있는 1차측 제어(PSR : Primary Side Regulation) Flyback 컨버터에 관한 연구이다. 낮은 부하 상태에서의 전원장치의 전력변환 효율을 증가시키기 위해서는 전력손실회로의 제거 및 대체가 중요하다. 본 논문에서는 낮은 부하 상태에서 상대적으로 전력소모가 큰 2차측 제어회로를 제거하고 보조권선 전압에 반영된 출력전압의 정보를 검출, 보존하도록 하여 Flyback 컨버터의 제어기 구현이 가능하도록 하는 출력전압 정보 검출회로를 설계하였다. 회로의 설계 및 검증은 Magnachip 0.35um, 700V CMOS 공정을 이용하였다.

• ETRI Journal
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• 제41권1호
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• pp.124-132
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• 2019

The energy balance (EB) model of a primary side regulation (PSR) fly-back converter in the discontinuous conduction mode (DCM) is discussed in this paper. Based on this EB model, the stability of a PSR fly-back converter in the pulse skipping mode (PSM) is analyzed, and a self-adapting modulation factor control strategy is proposed. Theoretical analysis and simulation results show that by saving an optocoupler and correlative circuits, which are necessary in traditional PSM fly-back converters, the modulation factor tolerance controlled by this method is 1.26% on average, corresponding to the ideal value. Compared with traditional fly-back PSM controllers, the power saved in the sampler/comparator modules is 87% on average for a load range of $1{\Omega}$ to $1k{\Omega}$.

• 전기학회논문지
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• 제60권6호
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• pp.1274-1279
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• 2011

The purpose of this paper is to present the manufacturing defect and damage pattern of a 3 phase 22.9/3.3kV oil immersed transformer, as well as to present an objective basis for the prevention of a similar accident and to secure data for the settlement of PL related disputes. It was found that in order to prevent the occurrence of accidents to transformers, insulating oil analysis, thermal image measurement, and corona discharge diagnosis, etc., were performed by establishing relevant regulation. The result of analysis performed on the external appearance of a transformer to which an accident occurred, the internal insulation resistance and protection system, etc., showed that most of the analysis items were judged to be acceptable. However, it was found that the insulation characteristics between the primary winding and the enclosure, those between the ground and the secondary winding, and those between the primary and secondary windings were inappropriate due to an insulating oil leak caused by damage to the pressure relief valve. From the analysis of the acidity values measured over the past 5 years, it is thought that an increase in carbon dioxide (CO2) caused an increase in the temperature inside the transformer and the increase in the ethylene gas increased the possibility of ignition. Even though 17 years have passed since the transformer was installed, it was found that the system's design, manufacture, maintenance and management have been performed well and the insulating paper was in good condition, and that there was no trace of public access or vandalism. However, in the case of transformers to which accidents have occurred, a melted area between the upper and the intermediate bobbins of the W-phase secondary winding as well as between its intermediate and lower bobbins. It can be seen that a V-pattern was formed at the carbonized area of the transformer and that the depth of the carbonization is deeper at the upper side than the lower side. In addition, it was found that physical bending and deformation occurred inside the secondary winding due to non-uniform pressure while performing transformer winding work. Therefore, since it is obvious that the accident occurred due to a manufacturing defect (winding work defect), it is thought that the manufacturer of the transformer is responsible for the accident and that it is lawful for the manufacture to investigate and prove the concrete cause of the accident according to the Product Liability Law (PLL).

• 한국응용약물학회:학술대회논문집
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• 한국응용약물학회 1997년도 춘계학술대회
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• pp.94-94
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• 1997

The objective of this study was to generate and characterize monoclonal antibodies against rat airway mucins, and therefore, should serve as a useful tool in studying the regulation of airway mucins using various in vivo rat models that are currently available. As an antigen, we used a high molecular mass mucin preparation purified from the spent media of rat tracheal surface epithelial cells in primary culture. Seven hybridomas were obtained which secrete monoclonal antibodies against the rat mucin among which mAbRT03 showed the highest immunoreactivity against the mucin based on ELISA. All of the antibodies secreted by these hybridomas recognized carbohydrate epitopes but not sialic acid residues since their immunoreactivity was completely abolished by treatment of the mucin with 20 mM periodate but not with neuraminidase. Further characterization of mAbRT03 showed that: (1) it belongs to the IgM type, (2) it binds to high molecular mass mucins based on both Western blot analysis and indirect immunoprecipitation, (3) it binds to the luminal side of tracheal epithelium as well as some goblet cells based on immunohistochemistry, and (4) it also recognizes in vive airway mucins from rats but not from human nor hamsters which have been purified from the airway lavage fluids. This is the first anti-rat airway mucin monoclonal antibody which has been developed against purified rat airway mucins. Therefore, mAbRT03 should be able to serve as an invaluable tool in studying the regulation of airway mucins using various intact rat models that are currently available.