Abstract.[Purpose] The aim of this study was to determine the effect of electrical stimulation on blood lactate after anaerobic muscle fatigue was induced in Taekwondo athletes.[Subjects] Twenty-four male collegiate Taekwondo athletes voluntarily participated in this study (from June 7, 2010 to June 18, 2010, a total of 2 weeks). Subjects were randomly divided into three groups of 8: a) Electrical stimulation group (ES) which received electrical muscle stimulation; b) the massage group which received massage; and the control group which took a rest after induction of anaerobic muscle fatigue. [Methods] This study was a double-blind randomized controlled trial. It was conducted at the sports science research laboratory of Kyungwoon University, Gumi, Korea. Muscle fatigue was induced via anaerobic exercise. Blood samples were collected when the athletes were in a relaxed state, immediately after anaerobic exercise, 15 minutes after anaerobic exercise, and 25 minutes after anaerobic exercise.[Results] Repeated measures ANOVA showed statistically significant differences in lactic acid concentration in the blood with time in the three groups, as well as among the three groups. The lactic acid concentrations in the blood was highest immediately after exercise, decreased significantly 15 min after exercise, and further decreased 25 min after exercise. Scheffe's post-hoc test revealed statistically significant differences between the massage group and the control group, and between the ES group and the control group, whereas no statistically significant difference was found between the massage group and the ES group. [Conclusion] Electrical stimulation was shown to enhance muscle fatigue recovery caused by anaerobic exercise by Taekwondo athletes.

A time-to-digital converter (TDC) for a low-power, wide-range all digital phase-locked loop (ADPLL) is presented. The proposed TDC uses an enabling signal with variable duration to achieve low power and wide range. For verification purpose, the ADPLL is fabricated in a 0.11 µm CMOS technology. The ADPLL dissipates 6.02mW at an output frequency of 1.68GHz and its output frequency is measured as 0.24-1.68 GHz from a 1.2 V supply.

We have developed a magnetic suspension and balance system (MSBS) having a test section of 36cm×40cm and being controlled around 5 axes, which can be operated with low electric power. We have developed the control method to support the model in the center of the test section. In order to evaluate the characteristics of this MSBS, we performed the calibration tests of magnetic forces on five axes and interference between these axes. We measured drag coefficients of a sphere and support interference in order to confirm the performance of this MSBS.

In this paper, we propose novel interface circuits using Dynamic Over-Driving (DOD) and Adaptive Sensing (AS) scheme for high speed and energyefficient interface on a chip. Our AS-receiver makes it possible to use very low swing because of its good noise immunity against the threshold voltage variations, and our DOD-driver reduces data transmission time even through heavy load capacitances. The simulation results show that the reduction of approximately 20% speed and 40% energy consumption is achieved for the proposed circuits, as compared with the conventional full CMOS inverters at low supply voltage (=1 SV).

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