• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.911-913
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• 2008

In this work, nonvolatile memory (NVM) devices for system on panel of flat panel display (FPD) were fabricated using low temperature polycrystalline silicon (LTPS) thin film transistor (TFT) technology with an oxide-nitride-oxynitride (ONOn) stack structure on glass. The results demonstrate that the NVM devices fabricated using the ONOn stack structure on glass have suitable switching characteristics for data storage with a low operating voltage, a threshold voltage window of more than 1.8 V between the programming and erasing (P/E) states after 10 years and its initial threshold voltage window (${\Delta}V_{TH}$) after $10^5$ P/E cycles.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.507-510
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• 2005

High voltage pulse power supply using Marx generator and solid-state switches is proposed in this study. The Marx generator is composed of 12 stages and each stage is made of IGBT stack, two diode stacks, and capacitor. To charge the capacitors of each stage in parallel, inductive charging method is used and this method results in high efficiency and high repetition rates. It can generate the pulse voltage with the following parameters: Voltage: up to 120kv Rising time: sub ${\mu}S$ Pulse width: up to $10{\mu}S$, Pulse repetition rate: 1000pps The proposed pulsed power generator uses IGBT stack with a simple driver and has modular design. So this system structure gives compactness and easiness to implement total system. Some experimental results are included to verify the system performances in this paper.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1870-1872
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• 1999

Performance of 20-cell stack for direct methanol fuel cell (DMFC) was tested at constant temperature. Electrode evaluation used to the stack was tested by the performance of a single cell. A new composite electrode prepared from active carbon cloth and high porous active carbon was developed for hydrophilic layer of the cell. Characteristics of a single cell using the composite electrode showed the current density of $500mA/cm^2$ at the cell voltage of 0.4V at $120^{\circ}C$. For the operating of 20 days. the cell voltage at constant cell current densty of $100mA/cm^2$ was slightly reduced from 0.62V to 0.53V with the cell voltage decay rate of 14.5%. Power of 20-cell stack at 5.3V, $100^{\circ}C$ was about 180W.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.3
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• pp.228-239
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• 2004

In this paper, an analytical model accounting for the quantum effects in MOSFETs has been developed to study the behaviour of $high-{\kappa}$ dielectrics and to calculate the threshold voltage of the device considering two dielectrics gate stack. The effect of variation in gate stack thickness and permittivity on surface potential, inversion layer charge density, threshold voltage, and $I_D-V_D$ characteristics have also been studied. This work aims at presenting a relation between the physical gate dielectric thickness, dielectric constant and substrate doping concentration to achieve targeted threshold voltage, together with minimizing the effect of gate tunneling current. The results so obtained are compared with the available simulated data and the other models available in the literature and show good agreement.

• Steel and Composite Structures
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• v.21 no.3
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• pp.573-588
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• 2016

Carbon Fiber Reinforced Plastic (CFRP) and Titanium Alloy (Ti6Al4V) stack, extensively used in aerospace structural components are assembled by fasteners and the holes are made using drilling process. Drilling of stack in one shot is a complicated process due to dissimilarity in the material properties. It is vital to have optimal machining condition and tool geometry for better hole quality and tool life. In this study the tool wear and hole quality were analysed by experimental analysis using three modified twist drills and online tool condition monitoring using Acoustics Emission (AE) sensor. Helix angle and point angle influence tool performance and cutting force. It was found that a tool geometry (TG1) with high helix angle of $35^{\circ}$ with low point angle $130^{\circ}$ results in reduction in thrust force of 150-500 N range but the TG2 also perform almost similar to TG1, but when compared with the AErms voltage generated during drilling it was found that progressive rise in voltage in TG1 is less with respect to TG2 which can be attributed to tool life. In process wear monitoring was done using crest factor as monitoring index. AErms voltage were measured and correlated with the performance of the drills.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.289-294
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• 2014

The stability of a solid oxide fuel cell (SOFC) stack is strongly dependent on the magnitude and profile of the internal chemical potential of the solid electrolyte. If the internal partial pressure is too high, the electrolyte can be delaminated from the electrodes. The formation of high internal pressure is attributed to a negative cell voltage, and this phenomenon can occur in a bad cell (with higher resistance) in a stack. This fact implies that the internal chemical potential plays an important role in determining the lifetime of a stack. In the present work, we fabricate planar type anode-supported cells ($25cm^2$) with a bi-layer electrolyte (with locally increased electronic conduction at the anode side) to prevent high internal pressure, and we test the fabricated cells under a negative voltage condition. The results indicate that the addition of electronic conduction in the electrolyte can effectively depress internal pressure and improve the cell stability.

• Transactions of the Korean hydrogen and new energy society
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• v.20 no.3
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• pp.202-207
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• 2009

A 75kW MCFC stack with the reactive area of 9,600cm$^2$ has been operated and validated in Boryeong thermal power plant. The 75kW MCFC stack was installed at the end of November 28, 2008 and started initial operation on December 23, 2008 after pretreated for about 20 days. At initial load operation, the stack showed the Open Circuit Voltage of 137V, which approaches the theoretical value. At the early stage of rated power operation, the stack displayed the voltage of 104V at the current of 754A and reached the maximum generating power of 78.5kW DC. This stack has been operated for 2,890 hours until April, 2009. In addition, the operation time of rated power records 1890 hours. This Operating result is scheduled to be reflected the design of l25kW stack.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.88-93
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• 2016

Soft starters are used with large induction motors in blowers, fans, pumps and the crane hoist drives. AC voltage controllers are used as soft starters in induction motors for starting and to adjust its speed. Soft-starter starting system uses phase control method of input electric source through the setting of the thyristor(SCR) firing angle ${\alpha}$, and it can control input electric source stably and continuously from beginning of starting to ending of starting. In this paper, it is verified that power stack of high-voltage with SCR series system possesses dielectric strength and input electric source is controlled stably by phase control. Especially, from the driving experimental of proposed soft-starter operating, a smoothing acceleration and inrush current decrease can be achieved by the series SCR trigger.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.374-380
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• 2015

In this paper, a dynamic model describing the 2 phase effect on the gas diffusion layer depending on load change of a fuel cell stack was developed to examine the effects of liquid water in fuel cell cathode gas diffusion layer on the fuel cell performance. For the developed model, 2 phase effect on the performance of a fuel cell stack depending on the load changes, concentration distribution of water vapor and oxygen inside a gas diffusion layer, the effect of the thickness and porosity of the gas diffusion layer on the fuel cell stack voltage were examined. As a result, a fuel cell stack voltage for the 2 phase model within the scope of the research become lower than that for the 1 phase model regardless of the load. Although oxygen molar concentration for the gas diffusion layer adjacent to the catalyst layer was the lowest, water vapor concentration is the highest. In addition, as thickness and porosity of the gas diffusion layer increased and decreased, respectively, the fuel cell stack voltage decreased.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.402-405
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• 2004

In this paper, the parallel operation of the IGBT and power stack for easy capacity enlargement series in the medium power capacity inverter system of the 660V voltage class is described. The parallel operation of the IGBT and power stack for 1.5MVA medium power inverter system's design is applied. The results of the parallel operation are described in this paper. The designed stack capacity for parallel operation is 800kVA class. For 1.5MVA inverter system, the 800kVA stack is applied with 2 parallel configurations. The 800kVA stack is designed with 3 parallel configurations of the IGBT Module. In this paper, the feasibility for easy capacity enlargement series in the medium power inverter by applying the parallel operation of the IGBT and power stack is verified. The experimental results show the good characteristics for the parallel operation of the IGBT and power stack.