A digit-serial multiplier for finite field GF(2/sup m/)

In this paper, an efficient digit-serial systolic array is proposed for multiplication in finite field GF(2/sup m/) using the standard basis representation. From the least significant bit first multiplication algorithm, we obtain a new dependence graph and design an efficient digit-serial systolic multiplier. If input data come in continuously, the proposed array can produce multiplication results at a rate of one every /spl lceil/m/L/spl rceil/ clock cycles, where L is the selected digit size. Analysis shows that the computational delay time of the proposed architecture is significantly less than the previously proposed digit-serial systolic multiplier. Furthermore, since the new architecture has the features of regularity, modularity, and unidirectional data flow, it is well suited to VLSI implementation.     

Characteristics of wide-gap hydrogenated amorphous SiC films prepared using electron cyclotron resonance CVD from acetylene

The deposition of hydrogenated amorphous silicon carbide (a-SiC:H) films from a mixture of silane, acetylene and hydrogen gas using the electron cyclotron resonance chemical vapor deposition (ECR-CVD) process is reported. The variation of the deposition and film characteristics such as the deposition rate, optical bandgap, photoluminescence and the infra-red (IR) absorption as a function of the hydrogen dilution is investigated. The deposition rate increases to a maximum value of 250 Å/min at a moderate hydrogen dilution ratio of 20 [hydrogen flow (sccm)/acetylene + silane flow (sccm)], and decreases in response to a further increase in the hydrogen dilution. There is no strong dependence of the optical bandgap of the hydrogen dilution within the dilution range investigated (10 to 60), and the optical bandgap calculated from the E₀₄ method varied marginally from 2.85 eV to 3.17 eV. The room temperature photoluminescence (PL) peak energy and intensity showed a prominent shift to a maximum value of 2.17 eV corresponding to maximum PL intensity at a moderate hydrogen dilution of 30. The PL intensity showed a strong dependence on the hydrogen dilution variation. IR absorption results show that films deposited at higher hydrogen dilution have more Si---C bonding.     

Daily planning and scheduling system for the EDS process in a semiconductor manufacturing facility

Operations management in a complex manufacturing environment is practiced hierarchically: production planning and scheduling in sequence since the integrated approach is not efficient and practical. Production targets and allocation to the equipment are determined in the planning procedure by considering the only the critical factors, and the detailed scheduling is determined with more information needed to accomplish the production targets provided in the planning step. There is always, therefore, a gap between the planning and scheduling procedure, and some control parameters or factors are used to control those gaps. In this paper an approach connecting two procedures is suggested, which can be applied in the EDS (electrical die sorting) or the probe process in the semiconductor manufacturing. The EDS process requires very flexible operation management since the manufacturing processing time is relatively short and the supply of upstream fabrication and the demand of downstream assembly have to be met simultaneously. Daily planning and scheduling procedure are modeled to minimize the tester change-over within the daily target. Because of the relatively long setup change-over time, daily planning and scheduling have to be performed so that the time needed for the device and probe card change is minimized as possible. Mathematical programming is suggested for the problem, and the modified model is developed which can be solved in a practical computational time on a daily base. The scheduling heuristic with the planning data obtained from the suggested model, is designed, and their performance is evaluated through the computational experiment.     

A raw material storage yard allocation problem for a large-scale steelworks

This paper addresses a raw material storage yard allocation problem at a large-scale steelworks. At the steelworks, raw materials such as coal and iron ore are imported by ships from overseas, discharged from the ships by unloading equipment, and transported into and stored in the yards. The stored materials then are transported and used in the production equipment such as steel mills. The yard allocation decision, i.e., where to store the materials, determines the travel distance of the materials as well as the storage efficiency of the yards. Here, the yard allocation problem is solved using a mixed integer programming model. The solution compares favorably with the current practice of the steelworks.     

Hydrogen production in fluidized bed by chemical-looping cycle

To investigate the feasibility of a chemical-looping hydrogen generation system, we investigated the reduction and water splitting reaction characteristics for three mediators and two reducing gas in a bubbling fluidized bed reactor (0.02 m I.D.). For three oxygen carrier particles (NiO/bentonite, Fe₂O₃/bentonite, (NiO:Fe₂O₃)/bentonite), hydrogen was used as a reduction gas and water was used as an oxidation gas. For (NiO: Fe₂O₃)/bentonite particle, carbon monoxide, which is the main component in the syngas from coal or heavy residue, was used as a reducing gas to check reactivity for the carbon containing fuels and carbon deposition characteristics. Based on the reactivity tests, (NiO: Fe₂O₃)/bentonite particle was selected as the best mediator for the chemical-looping hydrogen generation system to achieve stable continuous operation. This work was presented at the 6 ^th Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006.     

Measurement and calculation of swelling equilibria for water/poly(acrylamide-sodiumallylsulfonate) systems

Superabsorbent poly(acrylamide-sodiumallylsulfonate) was synthesized from acrylamide (AM) and sodiumallylsulfonate (SAS) by a solution polymerization method. N,N’-methylenebisacrylamide (BIS) was used as the crosslinker; potassium persulfite (PP) and N,N,N’,N’-tetra-methylenediamine (TMEDA) were used as the redox initiator during the synthesis. The absorption capacities of the synthesized superabsorbent poly(AM-SAS) were repeatedly measured to obtain the optimal poly(AM-SAS) according to the variations of monomer concentration at 298.15 K. Its maximal absorption capacity appeared as 811 times at 0.1 mol/L among from 0.01 mol/L to 0.16 mol/L of SAS concentrations. The swelling equilibria at those conditions from 298.15 K to 318.15 K were measured and used to estimate the parameters by correlating with the Flory-Huggins model. The swelling behavior could be described by the parameters and the calculated values agreed satisfactorily with the experimental data.     

Full software analysis and impedance matching of radio frequencyCMOS integrated circuits

We present a systematic analysis technique of complementary metal-oxide-semiconductor (CMOS) radio-frequency (RF) integrated circuits (ICs). A full simulation program with integrated circuit emphasis (SPICE) simulation of the whole chip including the package and the die, with the parameters extracted from purely software analysis, has been performed. It is shown that the RF impedance matching without S-parameter based techniques is possible and the measured results agree well with our SPICE-only software based technique     

The surface morphology of Li metal electrode

Surface morphological changes of Li powder compacted electrodes were investigated and compared with extruded Li foil electrodes during the dissolution (discharge)/deposition (charge) process. The area of dendrite growing surfaces was reduced remarkably for Li powder compacted electrodes. Impedance measurements showed that Li compacted powder electrodes had a lower resistance than Li foil electrodes. This is presumed to be related with resistance reduction due to increasing ion conductivity in the SEI (solid electrolyte interface) formed on the surface along with the increase of the reaction area for the powder electrode.