Architectural Design Issues in a Clockless 32‐Bit Processor Using an Asynchronous HDL

As technology evolves into the deep submicron level, synchronous circuit designs based on a single global clock have incurred problems in such areas as timing closure and power consumption. An asynchronous circuit design methodology is one of the strong candidates to solve such problems. To verify the feasibility and efficiency of a large‐scale asynchronous circuit, we design a fully clockless 32‐bit processor. We model the processor using an asynchronous HDL and synthesize it using a tool specialized for asynchronous circuits with a top‐down design approach. In this paper, two microarchitectures, basic and enhanced, are explored. The results from a pre‐layout simulation utilizing 0.13‐μm CMOS technology show that the performance and power consumption of the enhanced microarchitecture are respectively improved by 109% and 30% with respect to the basic architecture. Furthermore, the measured power efficiency is about 238 μW/MHz and is comparable to that of a synchronous counterpart.     

High-power CSI-fed induction motor drive with optimal power distribution based control

In this article, a current source inverter (CSI) fed induction motor drive with an optimal power distribution control is proposed for high-power applications. The CSI-fed drive is configured with a six-step CSI along with a pulsewidth modulated voltage source inverter (PWM–VSI) and capacitors. Due to the PWM–VSI and the capacitor, sinusoidal motor currents and voltages with high quality as well as natural commutation of the six-step CSI can be obtained. Since this CSI-fed drive can deliver required output power through both the six-step CSI and PWM–VSI, this article shows that the kVA ratings of both the inverters can be reduced by proper real power distribution. The optimal power distribution under load requirements, based on power flow modelling of the CSI-fed drive, is proposed to not only minimise the PWM–VSI rating but also reduce the six-step CSI rating. The dc-link current control of the six-step CSI is developed to realise the optimal power distribution. Furthermore, a vector controlled drive for high-power induction motors is proposed based on the optimal power distribution. Experimental results verify the high-power CSI-fed drive with the optimal power distribution control.     

Physicochemical properties and antioxidant activities of Korean traditional alcoholic beverage, yakju, enriched with mulberry

Mulberry fruits (Morus alba L.), rich in health beneficial compounds such as polyphenols, flavonoids, and anthocyananis, have traditionally been used as nutritional foodstuffs and fork medicines. In this study, physicochemical properties and antioxidant activities of a traditional Korean alcoholic beverage ``yakju' enriched with mulberry were evaluated. The beverage was enriched with smoothies prepared from Korean mulberry cultivars of Cheongilppong (CP), Suwonppong (SP), and Daesungppong (DP). In comparison to the control, an increase in alcohol content and total acidity and a decrease in sugar level in yakju enriched with mulberry were observed during 15 d of fermentation. The total polyphenol and total flavonoid content increased in the following order: DP yakju > SP yakju > CP yakju > control yakju. In contrast, the anthocyanin content decreased during the fermentation periods. The trans-resveratrol content of mulberry yakju increased during the fermentation and the resveratrol content of DP yakju (0.24 mg/L) was significantly higher than that of SP yakju (0.21 mg/L) and CP yakju (0.14 mg/L) on the 15th day of fermentation (P < 0.05). The antioxidant activities of mulberry yakju, which was assessed using the 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2'-azino-bis-(3-ethylbenozothiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and reducing power assays, decreased during the 1st day of fermentation and increased into thereafter. The increase in antioxidant activities of mulberry yakju might have been affected primarily by the total flavonoid and total polyphenol content with increasing alcohol concentration, as a good extractor, during the fermentation; however, the antioxidant activities may have also been affected by the total anthocyanin content up to the 1st day of fermentation. PRACTICAL APPLICATION: The physicochemical properties and antioxidant activities of a traditional Korean alcoholic beverage ``yakju' enriched with mulberry were investigated. This analysis is important for the potential applications of mulberry yakju as functional alcoholic drinks.     

Characteristics of milk tablets supplemented with nanopowdered eggshell or oyster shell

This study was performed to investigate the characteristics of milk tablets supplemented with nanopowdered eggshell (NPES) or nanopowdered oyster shell (NPOS). The particle size of NPES, NPOS, NPES with zinc (Zn‐NPES) and NPOS with activated zinc (Zn‐NPOS) ranged from 20 to 300 nm. The hardness of the milk tablets containing these calcium supplements did not differ significantly from that of the control milk tablets (P > 0.05). Regarding the sensory properties, the appearance, flavour, taste, texture and cumulative sensory score of all the test tablets were similar to those of the control tablets. In conclusion, the quality of all the test milk tablets was similar to that of the control.     

Neuronal cell protective and antioxidant effects of phenolics obtained from Zanthoxylum piperitum leaf using in vitro model system

In order to obtain basic data for the utilisation of Zanthoxylum piperitum leaf as a functional substance in the food industry, the antioxidative and neuronal cell protective effects of silica-gel open column chromatographic fractions, obtained from Z. piperitum leaf, were examined. ABTS and FRAP assays indicated that the ZP4 fraction (eluted with methanol/chloroform, 1:4, v/v) of Z. piperitum leaf was a more potent radical-scavenger and reducing agent than the other five fractions. The ZP4 fraction also presented protective effects against H₂O₂-induced neurotoxicity in a dose-dependent manner. Therefore, our study verified that the ZP4 fraction has strong antioxidative and neuronal protective effects which are correlated with its high level of phenolics, particularly quercitrin, afzelin, and hyperoside. These phenolics of Z. piperitum leaf can be utilised as effective and safe functional food substances, i.e., natural antioxidants, and may reduce the risk of neurodegenerative disorders.     

Cholesterol removal from homogenized milk with beta-cyclodextrin

This study was carried out to determine optimum conditions of five different factors (beta-cyclodextrin concentration, mixing temperature, mixing time, centrifugal force, and centrifugation time) in reduction of cholesterol in 3.6% fat, homogenized milk by application of beta-cyclodextrin. beta-Cyclodextrin at 0.5 to 1.5% provided 92.2 to 95.3% removal of cholesterol when mixed at 10 degrees C for 10 min. Among other factors, mixing time (5 to 20 min) did not significantly affect cholesterol removal. Removal was enhanced with increasing centrifugal forces up to 166x g (95.9%) but decreased thereafter. Various centrifugation times (5 to 20 min) did not have significant effects. Based on these results, we suggest that the optimum conditions for the process are addition of 1.5% beta-cyclodextrin, mixing temperature of 10 degrees C, 10-min mixing time, and centrifugation at 166x g for 10 min.     

Aspergillus oryzae strains isolated from traditional Korean Nuruk: Fermentation properties and influence on rice wine quality

Forty-seven strains of Aspergillus oryzae isolates from Korean nuruks were compared for their brewing characteristics. A. oryzae YI-A6 and YI-A7 showed the highest acid α-amylase, glucoamylase, and carboxypeptidase activities, respectively. Sixteen isolates with high amylolytic or proteolytic enzyme activities were selected for investigation of their rice wine fermentation characteristics. After 12 days of brewing at 15°C, ethanol concentrations were 10.2–14.3% for A. oryzae strains. Fermentation rates were the highest for YI-A7. Most rice wine samples fermented with nuruk strains had lower concentrations of off-flavor compounds than the control did. All mean sensory attribute values significantly differed among samples. Pearson correlation coefficients showed that glucoamylase activity was positively correlated to both ethanol productivity and overall harmony (p<0.01). Thus, glucoamylase activity was identified as the best factor for screening Aspergillus strains for use in rice wine brewing.