We introduced Tb 3+ co-dopants into well-known orthosilicate phosphors such as Sr 2 SiO 4 :Eu 2+ and ͑Sr,Ba͒ 2 SiO 4 :Eu 2+ . Tb 3+ co-doping had a positive influence on the overall photoluminescence ͑PL͒ intensity of ␤-Sr 2 SiO 4 :Eu 2+ , Tb 3+ and ␣Ј-͑Sr 0.7 Ba 0.3 ͒ 2 SiO 4 :Eu 2+ , Tb 3+ . In the absence of barium incorporation, Tb 3+ co-doping induced phase transformation of the Sr 2 SiO 4 host from the ␤ to the ␣Ј phase, such that the peak location redshifted and the peak intensity decreased significantly. For ␤-Sr 2 SiO 4 :Eu 0.02 2+ and ␣Ј-͑Sr 0.7 Ba 0.3 ͒ 2 SiO 4 :Eu 0.02 2+ , we detected inactive energy transfer from Eu 2+ to Tb 3+ , despite the fact that the PL intensity was improved by the Tb 3+ co-doping, meaning that the Eu 2+ emission never decreased as the Tb 3+ concentration increased. There was clear evidence supporting an energy transfer between Eu 2+ and Tb 3+ for ␣Ј-Sr 2 SiO 4 :Eu 2+ , Tb 3+ despite no conspicuous practical improvement in the PL properties. The positive influence of Tb 3+ co-doping comes not from the energy transfer, but, rather, simply from the local structure change around the Eu 2+ activator in the host. Divalent europium-doped orthosilicates have attracted considerable attention as promising phosphors since their application to light emitting diodes ͑LEDs͒ 1-5 . Even after the advent of various, more promising, nitride phosphors, 6-10 the orthosilicate phosphor still serves as a key phosphor in some commercially available white LEDs. To achieve successful use in LED applications, barium and strontium were incorporated together into an ␣Ј-Sr 2 SiO 4 structure, and there has been no further alteration of the basic ␣Ј-͑Sr,Ba͒ 2 SiO 4 composition. However, recent Tb 3+ co-doping reportedly had a positive influence on the photoluminescence ͑PL͒ of ␣Ј-͑Sr,Ba͒ 2 SiO 4 :Eu 2+ , Tb 3+ . 11,12 Hiramatsu et al. 11,12 argued that a brisk energy transfer takes place between Eu 2+ and Tb 3+ in the ␣Ј-͑Sr,Ba͒ 2 SiO 4 host and the energy transfer leads to a positive impact on the LED function. It is true that a certain degree of energy transfer obviously occurs in the ␣Ј-͑Sr,Ba͒ 2 SiO 4 :Eu 2+ , Tb 3+ system. However, the composition of the ␣Ј-͑Sr,Ba͒ 2 SiO 4 :Eu 2+ , Tb 3+ system that Hiramatsu et al. 11,12 adopted deviated from the conventional composition, especially in terms of Eu 2+ activator concentration. These researchers adopted a relatively low Eu 2+ activator concentration, such that the effect of the energy transfer between Eu 2+ and Tb 3+ could be slightly exaggerated. To make the Tb 3+ co-doping induced energy transfer contribute to the improvement in the PL intensity and color chromaticity and, hence, to secure a higher practicality, we introduced Tb 3+ co-doping along with a higher, more realistic Eu 2+ activator concentration level. Also, we examined the Tb 3+ co-doping effect separately for both the ␣Ј-and ␤-Sr 2 SiO 4 structures. Namely, we introduced Tb 3+ co-doping into ␣Ј-Sr 2 SiO 4 :Eu 0.02 2+ , ␤-Sr 2 SiO 4 :Eu 0.02 2+ , and ␣Ј-͑Sr 0.7 Ba 0.3 ͒ 2 SiO 4 :Eu 0.02 2+...

Power-gating has been widely used to reduce subthreshold leakage current. However, the extent of leakage saving through power-gating diminishes with technology scaling due to gate leakage of data-retention circuit elements. Furthermore, power-gating involves substantial increase of area and wirelength. A circuit technique called supply switching with ground collapse (SSGC) has recently been proposed to overcome the limitation of power-gating. The circuit technique is successfully applied to the register file of ARM9 microprocessor in a 1.2 V, 65-nm CMOS process, and the measured result is reported for the first time. The leakage current is reduced by a factor of 960 on average of 83 dies at 25 C, and by a factor of 150 at 85 C. Compared to a register file implemented in conventional power-gating, leakage current is cut by a factor of 2.2, demonstrating that SSGC can be a substitute for power-gating in nanometer CMOS.

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The contact in the valve train system is known to be the part subject to significant load in an automobile engine. For such reason, the wear of the contact accounts for the greatest portion of entire friction loss of an engine, leading to the occurrence of abnormal wear. In order to reduce the wear in the valve train, this study first formed a crn layer to increase the bonding force with the base metal using the pvd coating method and then applied a 2-layer coating that formed the wc/c layer with low friction/wear resistance characteristics. In addition, it examined the friction characteristics occurring between the cam and tappet by using the dedicated wear tester and found that the friction torque value was reduced significantly through comparison testing with the existing part when the crn+wc/c coating was applied.