Abstract: Disclosed is a method for removing sludge in a crude oil storage tank by use of thermal oil discharged from a distillation tower of an oil refinery, such as atmospheric residue, vacuum residue, or vacuum gas oil, and recovering oil having various applications by separating inorganics therefrom. The method is advantageous in terms of minimizing air pollution because of utilizing a closed system, drastically reduced washing time of crude oil storage tank, and continuous removal of the sludge. Additionally, the recovered oil can be provided as fuel oil, marine oil or a feed for secondary treatment processes, such as up-grading processes of heavy oil.

Abstract: Disclosed is a method for preparing DL-&agr;-tocopherol through the condensation of isophytol or phytol derivatives and trimethylhydroquinone (TMHQ) using a catalyst system comprising a divalent metal halogen compound, silica gel and/or silica-alumina, and a Brönsted acid. Isophytol or phytol derivatives are slowly added to trimethylhydroquinone for the condensation thereof at 80 to 135° C. over 30 to 60 min in the presence of the metal halogen and the silica gel and/or silica-alumina. In the presence of the Brönsted acid, the intermediates are converted into the product. The silica gel and/or silica-alumina is washed with a polar solvent for recovery. The catalyst system can remarkably reduce side-reactions upon the condensation of isophytol or phytol derivatives and TMHQ, thus producing DL-&agr;-tocopherol with a high purity at a high yield.

Abstract: A magnetron is disclosed in which the structure of the choke is altered, so that when designing the choke, the design allowance range is expanded so as to realize the optimum efficiency. Thus the unnecessary harmonic waves are more inhibited, and the coupling of the output part is improved owing to the impedance of the choke, thereby doubling the output and efficiency. The first choke includes: a first cylindrical body; a flange part extending from the top of the cylindrical body toward the anode seal; and a supporting means extending from the flange part toward the cylindrical body. The second choke includes: a cylindrical body; and a flange part extending from the top of the cylindrical body toward the anode seal. Thus the first and second chokes maintain a proper gap between them owing to the supporting means.

Abstract: A method for manufacturing a phase shift mask includes the steps of forming a shift layer, a metal layer and a photoresist layer on a substrate subsequently, patterning the photoresist layer into a predetermined configuration, thereby obtaining a first, a second, a third and a fourth photoresist patterns, forming a chemical swelling process (CSP) chemical layer on the photoresist patterns and an exposed portion of the substrate, patterning the CSP chemical layer using masks over the first and the fourth photoresist patterns, whereby the CSP chemical layer on the first and the fourth photoresist patterns remains thereon, patterning an exposed portion of the metal layer into the predetermined configuration using the second and the third photoresist patterns as masks, patterning the exposed portions of the shift layer into the predetermined configuration, and removing the first and fourth photoresist patterns.

Abstract: A method for designing a microwave oven magnetron includes design for a permissible range of a length of a choke for suppression of a harmonic higher than the fourth harmonic. The inventive magnetron includes; a cathode with a filament; a cylindrical metal anode around the cathode; a vane fixed onto the inner side of the anode for providing a plurality of resonant cavities radially directed toward the cathode; an antenna feeder having an outer diameter .PHI..sub.1 ; upper and lower magnets fixed to upper and lower yokes; and upper and lower magnetic poles which provide paths of a magnetic circuit. An anode seal having an opening whose inner diameter .PHI..sub.4 serves as a magnetic circuit path and a supporter of a body. A metal choke (having an inner diameter .PHI..sub.2, an outer diameter .PHI..sub.3, and a length La) is installed fixed onto the inner side of the anode seal and surrounds the antenna feeder in order to suppress over a fourth higher harmonic generated through the anode seal.

Abstract: An anticorrosive treatment method for a separator of a molten carbonate fuel cell is provided. As conventional anticorrosive treatment methods for a wet-seal area in an separator, there are a molten aluminium coating method, a physical vapor deposition method, a slurry coating method, a spray coating method, a pack cementation method and a vacuum evaporation method. Defects due to high temperature thermal treatment corrodes even stainless steel base materials to thus shorten the lifetime of the fuel cell. Further, to sufficiently assure an anticorrosive capability of the separator wet-seal area, a coating ratio should be heightened finally, which makes fabrication of the large-area separator difficult, and manufacturing costs high. To solve the conventional problems, nickel and aluminium are coated in turn on a base material of stainless steel or an thin aluminium film is coated or bonded thereon to then perform diffusion process, which simplifies a manufacturing process and lowers a manufacturing cost.

Abstract: A digital wireless private branch exchange system comprising a system body, a terminal device and a base station controller.

Abstract: A composite decoding device for an MPEG-2 multichannel audio decoder. The composite decoding device is capable of simultaneously decoding information coded in a dynamic crosstalk coding manner and information coded in a phantom coding manner. To this end, the composite decoding device comprises an arithmetic unit for receiving a control word, information and a scale factor from a first-in-first-out memory, performing an arithmetic operation with respect to the received information and scale factor on the basis of a dynamic crosstalk coding manner or a phantom coding manner determined by the received control word and outputting the arithmetic result to a dual port memory, and a controller for generating a plurality of sequential control signals in response to the control word from the first-in-first-out memory to control the arithmetic unit.

Abstract: A delay circuit for a semiconductor integrated circuit having an unvaried delay time without the deterioration of a signal propagation characteristic under the influence of a voltage source and an ambient temperature.