Abstract: The present invention provides a method of synthesizing a nano-sized transition metal catalyst on a carbon support, including dissolving a stabilizer in ethanol thus preparing a mixture solution, adding a support to the mixture solution thus preparing a dispersion solution, dissolving a transition metal precursor in ethanol thus preparing a precursor solution, mixing the precursor solution with the dispersion solution with stirring, and then performing reduction, thus preparing the nano-sized transition metal catalyst. This method enables the synthesis of transition metal nanoparticles supported on carbon powder having a narrow particle size distribution and a wide degree of dispersion through a simple process, and is thus usefully applied to the formation of an electrode material or the like of a fuel cell.

Abstract: The present invention relates to a process for preparing electrode catalyst materials for a polymer electrolyte membrane fuel cell (PEMFC), and particularly to a high-performance platinum-non-platinum mixed electrode catalyst (Pt—RuOs/C) having a physically mixed structure of RuOs alloy and platinum materials, which is prepared by adding a small amount of platinum (Pt) to RuOs alloy materials highly dispersed on a carbon support, where the amount of platinum used is drastically reduced as compared to the conventional platinum materials, thus lowering the manufacturing cost.

Abstract: There is provided a method and apparatus for output pulse width modulation in a digital amplifier including: a determining step of adding or subtracting a value corresponding to a predetermined offset to or from an input audio signal alternately according to a period of the input audio signal, thereby determining a sign of a resulting value of adding or subtracting; a switching step of outputting the input audio signal to a first port based on the determined sign, or outputting the input audio signal to a second port after inverting the input audio signal into a positive number; an adjusting step of adding a value of a predetermined switching time to the audio signals output from the first port and the second port, and outputting a resulting value of adding; and a modulating step of performing pulse width modulation on the audio signals output from the adjusting step and outputting a first modulation signal and a second modulation signal.

Abstract: A method of preparing a platinum alloy catalyst for a fuel cell electrode includes: (a) adding a carbon material, a platinum precursor, and a transition metal precursor to ethanol and dispersing the mixture; (b) adding sodium acetate powder or an ammonia solution containing ethanol as a solvent to the solution obtained in step (a) and stirring the resulting solution; (c) adding sodium borohydride to the solution obtained in step (b) and reducing the metal ions of the platinum precursor and the transition metal precursor; and (d) obtaining a platinum alloy catalyst in the form of powder through washing and drying processes. This method can reduce the amount of platinum to be used for manufacturing a fuel cell electrode and thereby reduce the manufacturing cost.

Abstract: The present invention relates to a process for preparing electrode catalyst materials for a polymer electrolyte membrane fuel cell (PEMFC), and particularly to a high-performance platinum-non-platinum mixed electrode catalyst (Pt—RuOs/C) having a physically mixed structure of RuOs alloy and platinum materials, which is prepared by adding a small amount of platinum (Pt) to RuOs alloy materials highly dispersed on a carbon support, where the amount of platinum used is drastically reduced as compared to the conventional platinum materials, thus lowering the manufacturing cost.

Abstract: There is provided a method and apparatus for output pulse width modulation in a digital amplifier including: a determining step of adding or subtracting a value corresponding to a predetermined offset to or from an input audio signal alternately according to a period of the input audio signal, thereby determining a sign of a resulting value of adding or subtracting; a switching step of outputting the input audio signal to a first port when the determined sign is positive, and outputting the input audio signal to a second port after inverting the input audio signal into a positive number when the determined sign is negative; an adjusting step of adding a value corresponding to a pulse width for a minimum time required for switching to the audio signals output from the first port and the second port, and outputting a resulting value of adding; and a modulating step of performing pulse width modulation on the audio signals output from the adjusting step and outputting a first modulation signal and a second modul

Abstract: A bipolar plate and a direct liquid feed fuel cell stack are provided. The bipolar plate includes a manifold that is coupled with the fuel/oxidant path holes and a plurality of flow channels that are coupled with the manifold. The flow channels are divided into a plurality of groups, where the flow channel of each group forms a serpentine flow path and a length of each flow channel is substantially the same.

Abstract: A bipolar plate for fuel cells includes a plurality of flow paths in which fuel flows. The flow paths include a first flow path formed by a plurality of flow channels and a second flow path formed by a plurality of islands. A direct liquid fuel cell stack comprises the bipolar plate.

Abstract: The present invention relates to an audio amplifier using a pulse width modulation, and more particularly, to a pulse width modulation type audio amplifier which an average switching frequency or a cutoff frequency of a low pass filter is variable in accordance with frequency of input signal.

Abstract: An image format converting method and apparatus are provided. The image format converter includes a pre-filter for pre-filtering the input image and for outputting a pre-filtered signal, and a format converter for bi-linear interpolating the pre-filtered signal, according to a predetermined aspect ratio, and for outputting a format converted signal. Therefore, the image format converter can have simple structure by adding the pre-filter, before the format converter using simple bi-linear interpolation, so that the image can be enlarged or reduced while remaining distinct and without aliasing.

Abstract: The present invention relates to an audio amplifier using a pulse width modulation, and more particularly, to a pulse width modulation type audio amplifier which an average switching frequency or a cutoff frequency of a low pass filter is variable in accordance with frequency of input signal.

Abstract: An image format converting method and apparatus are provided. The image format converter includes a pre-filter for pre-filtering the input image and for outputting a pre-filtered signal, and a format converter for bi-linear interpolating the pre-filtered signal, according to a predetermined aspect ratio, and for outputting a format converted signal. Therefore, the image format converter can have simple structure by adding the pre-filter, before the format converter using simple bi-linear interpolation, so that the image can be enlarged or reduced while remaining distinct and without aliasing.

Abstract: An image enhancing method using a mean-separate histogram equalization method is disclosed. An input image signal is divided into two sub-images in a picture unit according to a mean level of the input image signal. Then, cumulative density functions for each of the sub-images are calculated. Afterwards, the input sample is mapped into two gray levels, each of which belongs to a first range and a second range, by using first and second transform functions defined by use of the cumulative density functions, respectively. Finally, one of two mapped levels is selected depending on the magnitude of the input sample. As a result, the brightness of the given image can be preserved while the contrast is enhanced.

Abstract: A method of accurately detecting rapid motion as well as slow motion using two field memories in an interlaced-progressive scanning converter for changing an interlaced-scanned signal into a progressive-scanned signal. A threshold coefficient, which is used for comparison to a difference between temporal interpolation and spatial interpolation values to determine whether a picture is in motion, is determined dynamically in the disclosed method, rather than being a fixed, predetermined value. The threshold coefficient is determined based upon a degree of correlation between data of pixels above and below a pixel to be interpolated. Detection of whether the picture is stationary is based upon the difference between the data of pixels above and below the pixel to be interpolated is greater than a stationary coefficient. The threshold coefficient is maintained as being no less than the value of the stationary coefficient.

Abstract: A histogram-equalization method and circuit for enhancing an image signal represented by a predetermined number of gray levels is presented. The method calculates a cumulative density function and a mean level in a unit of a picture, and maps an input sample into a new gray level according to a transform function which is defined by use of the cumulative density function and the mean level. The method may also include a step of obtaining a compensated mean level by adding to the mean brightness level, so that the input sample is mapped into the compensated mean level according to the mean level. Thus, a brightness compensation may be carried out along with the contrast enhancement of the image.

Abstract: A scroll-type compressor has a scroll plate with at least first and second pressure equalizing passages formed in its end plate such that the first and second pressure equalizing passages will be in the same crescent shaped pocket during at least a portion of a crescent shaped pocket's radially inward movement. The minimum pressure in a back pressure pocket will be adequate to maintain a good seal, any pressure increases will increase in accordance with the increased pressure in the crescent shaped pockets. At no point are both of the pressure equalizing passages blocked and, therefore, the pressure in the interior space does not overwhelm the effective functioning of the back pressure pocket.

Abstract: A method for interpolating pixel data of an omitted line by use of pixel data from an interlaced scan and an apparatus therefor are described. The pixel interpolation method and apparatus efficiently interpolate edges having various slopes according to a degree of correlation. When an edge has a gentle slope due to extensive correlation, interpolation is performed using a wide-vector. When an error occurs due to high-frequency components such as when bidirectional edges are found, simple vertical interpolation is performed.