Abstract: Provided are a semiconductor memory device and a memory system including the same. The semiconductor memory device includes a power-up signal generator configured to generate a power-up signal in response to a memory voltage reaching a target voltage level, an initializer configured to generate an initialization signal in response to the power-up signal and a reset signal and to generate an initial refresh command in response to completion of an initialization operation, and a memory cell array including a plurality of memory cells connected between a plurality of word lines and a plurality of bit lines, the memory cell array configured to perform an initial refresh operation on the plurality of memory cells in response to the initial refresh command.

Abstract: Provided are a semiconductor memory device and a memory system including the same. The semiconductor memory device includes a power-up signal generator configured to generate a power-up signal in response to a memory voltage reaching a target voltage level, an initializer configured to generate an initialization signal in response to the power-up signal and a reset signal and to generate an initial refresh command in response to completion of an initialization operation, and a memory cell array including a plurality of memory cells connected between a plurality of word lines and a plurality of bit lines, the memory cell array configured to perform an initial refresh operation on the plurality of memory cells in response to the initial refresh command.

Abstract: A beta zeolite catalyst for the preparation of a BTEX (benzene, toluene, ethylbenzene, xylene) mixture from polyaromatic hydrocarbons and a preparation method of the same are disclosed. The beta zeolite catalyst demonstrates high conversion of polyaromatic hydrocarbons and high BTEX production yield by containing optimum contents of the group VIB metals and cocatalysts, so that it can be effectively used as a beta zeolite catalyst for the production of BTEX.

Abstract: The present invention relates to a high-strength silicoaluminophasphate-34 (SAPO-34) microsphere catalyst, a method for preparing the same, and a method for preparing light olefins by using the same, and when described in more detail, the present invention relates to a method for preparing a SAPO-34 microsphere catalyst, including: spray drying a mixed slurry including a matrix, a binder, an additive, and the like to a SAPO-34 slurry prepared by a hydrothermal synthesizing method using various organic templates such as tetraethylammonium hydroxide (TEAOH), and the like alone or in mixtures to prepare microspheres, and firing the microspheres, and to a SAPO-34 microsphere catalyst for a circulating-fluidized bed reactor, prepared by the preparation method. The SAPO-34 microsphere catalyst of the present invention has excellent reaction activity while having high strength, and thus is appropriate for use in a circulating-fluidized bed reactor requiring high strength of the catalyst.

Abstract: The present invention relates to a beta zeolite catalyst for the preparation of a BTEX (benzene, toluene, ethylbenzene, xylene) mixture from polyaromatic hydrocarbons and a preparation method of the same. The beta zeolite catalyst of the present invention demonstrates the high conversion of polyaromatic hydrocarbons and the high BTEX production yield by containing the optimum contents of the group VIB metals and cocatalysts, so that it can be effectively used as a beta zeolite catalyst for the production of BTEX.

Abstract: The present invention provides a method for preparing dialkyl carbonate from urea or alkyl carbamate and alkyl alcohol using an ionic liquid comprising a cation, which produces a hydrogen ion, and a hydrophobic anion containing fluorine with high temperature stability in the presence of catalyst containing a metal oxide or hydrotalcite. Since the present invention can prepare dialkyl carbonate at a pressure lower than those of existing methods, it does not require an expensive pressure control device and peripheral devices for maintaining high pressure including the installation cost. It is also the method for preparing a dialkyl carbonate with high yield, thus improving economical efficiency. Moreover, the method of the present invention hardly produces any waste during the process and is thus an eco-friendly method.

Abstract: In a method of operating a solid state drive including a non-volatile memory, a volatile memory and a controller, the controller reads fail information of the volatile memory from a fail information region included in the non-volatile memory. The controller maps a logical address of data to a physical address of the volatile memory based on a bad address list and a clean address list that are generated based on the fail information. The controller loads the data into the volatile memory according to the address mapping. The method of operating a solid state drive may block access to fail addresses corresponding to failed cells included in the solid state drive by sequentially mapping logical addresses to physical addresses of a volatile memory included in the solid state drive based on a clean address list and a bad address list that are generated based on a fail information.

Abstract: Disclosed is a method for preparing a dialkyl carbonate, in which a dialkyl carbonate such as dimethyl carbonate is economically prepared in an environmentally-friendly manner at a higher yield while reducing generation of a by-product. The method for preparing the dialkyl carbonate includes reacting urea, an alkyl carbamate having 1 to 3 carbon atoms, or a mixture thereof with a monovalent alcohol having 1 to 3 carbon atoms in the presence of a room temperature ionic liquid and a catalyst including a salt of a transition metal or a rare earth metal.

Abstract: The present invention provides a method for preparing dialkyl carbonate from urea or alkyl carbamate and alkyl alcohol using an ionic liquid comprising a cation, which produces a hydrogen ion, and a hydrophobic anion containing fluorine with high temperature stability in the presence of catalyst containing a metal oxide or hydrotalcite. Since the present invention can prepare dialkyl carbonate at a pressure lower than those of existing methods, it does not require an expensive pressure control device and peripheral devices for maintaining high pressure including the installation cost. It is also the method for preparing a dialkyl carbonate with high yield, thus improving economical efficiency. Moreover, the method of the present invention hardly produces any waste during the process and is thus an eco-friendly method.

Abstract: Disclosed is a method for preparing a dialkyl carbonate, in which a dialkyl carbonate such as dimethyl carbonate is economically prepared in an environmentally-friendly manner at a higher yield while reducing generation of a by-product. The method for preparing the dialkyl carbonate includes reacting urea, an alkyl carbamate having 1 to 3 carbon atoms, or a mixture thereof with a monovalent alcohol having 1 to 3 carbon atoms in the presence of a room temperature ionic liquid and a catalyst including a salt of a transition metal or a rare earth metal.

Abstract: The present invention provides a method for preparing dialkyl carbonate from urea or alkyl carbamate and alkyl alcohol using an ionic liquid comprising a cation, which produces a hydrogen ion, and a hydrophobic anion containing fluorine with high temperature stability in the presence of catalyst containing a metal oxide or hydrotalcite. Since the present invention can prepare dialkyl carbonate at a pressure lower than those of existing methods, it does not require an expensive pressure control device and peripheral devices for maintaining high pressure including the installation cost. It is also the method for preparing a dialkyl carbonate with high yield, thus improving economical efficiency. Moreover, the method of the present invention hardly produces any waste during the process and is thus an eco-friendly method.

Abstract: The present invention relates to a high-strength silicoaluminophasphate-34 (SAPO-34) microsphere catalyst, a method for preparing the same, and a method for preparing light olefins by using the same, and when described in more detail, the present invention relates to a method for preparing a SAPO-34 microsphere catalyst, including: spray drying a mixed slurry including a matrix, a binder, an additive, and the like to a SAPO-34 slurry prepared by a hydrothermal synthesizing method using various organic templates such as tetraethylammonium hydroxide (TEAOH), and the like alone or in mixtures to prepare microspheres, and firing the microspheres, and to a SAPO-34 microsphere catalyst for a circulating-fluidized bed reactor, prepared by the preparation method. The SAPO-34 microsphere catalyst of the present invention has excellent reaction activity while having high strength, and thus is appropriate for use in a circulating-fluidized bed reactor requiring high strength of the catalyst.

Abstract: The present invention provides a method for preparing dialkyl carbonate from urea or alkyl carbamate and alkyl alcohol using an ionic liquid comprising a cation, which produces a hydrogen ion, and a hydrophobic anion containing fluorine with high temperature stability in the presence of catalyst containing a metal oxide or hydrotalcite. Since the present invention can prepare dialkyl carbonate at a pressure lower than those of existing methods, it does not require an expensive pressure control device and peripheral devices for maintaining high pressure including the installation cost. It is also the method for preparing a dialkyl carbonate with high yield, thus improving economical efficiency. Moreover, the method of the present invention hardly produces any waste during the process and is thus an eco-friendly method.

Abstract: This invention relates to a method and apparatus for on-line measurement of permeation characteristics (transmitting chemicals) through dense nonporous membrane. This invention is intended to facilitate various research activities, such as simultaneous analyses of diffusion coefficient, solubility coefficient, permeation rate and permeant composition, and presentation of new analysis about the permeation behavior, kinetics and so on. The object of this invention is to provide the method and apparatus for measurement of permeation characteristics of permeants in liquid, vapor or gas phase through dense nonporous membrane and more practicuraly, to provide permeation apparatus for measurement of permeation characteristics by analyzing permeation rate and permeation concentration of permeants through an on-line type dense porous membrane with time, not only for a steady state but also for an unsteady state in an accurate and reliable manner.

Abstract: This invention relates to a polyion complex separation membrane with a double structure, which is applicable in the separation process of a water-soluble mixture having ionic molecules or particles by means of reverse osmotic pressure for the purposes of recovering expensive ionic organic materials such as anionic emulsifiers from the waste water. More particularly, this invention relates to said membrane having anionic polymers, as substrate, which is immersed into a cationic polymer solution containing a multivalent ion cross-linking agent, by which a cross-linkage within the internal of the separation membrane is achieved, thereby forming an ion complex between ionic polymers of opposite ion at the surface of the separation membrane to yield a stable separation membrane of a double structure.

Abstract: The present invention relates to a process for preparing the controlled-release chitosan microcapsule, more specifically to a process for preparing the sustained-release chitosan microcapsule capable of releasing at an appropriate rate for a long time, which is characterized by: a) Biodegradable chitosan polymer is used for the capsule material; b) The capsule is kept stable during the release time by the rapid and effective crosslinking reaction between the chitosan polymer and the double crosslinking agent on the surface of tiny particles formed by a new emulsion interface reaction method using a double crosslinking agent of sulfuric acid and glutaraldehyde; and c) The microcapsule which is smaller than several &mgr;m s can be easily formed and the capsule is kept stable for a long release time because an insoluble polymer film whose source material is biodegradable is formed after the release.

Abstract: The present invention relates to a method and an apparatus for concentrating an aqueous PTFE emulsion in which a raw, aqueous PTFE emulsion containing fluorinated surfactants is concentrated by an electrodialysis technique using at least one nonionic surfactant as an anti-flocculation agent and a volatile electrolyte such that the formation of floccules is prevented.