Novel transformer active filters

Novel transformer active filters are proposed to obtain high attenuation of voltage or current ripple without deteriorating the transient response of the system considered. Experimental results show that the scheme gives good steady-state performance of the power supply     

Kriging interpolation methods in geostatistics and DACE model

In recent study on design of experiments, the complicate metamodeling has been studied because defining exact model using computer simulation is expensive and time consuming. Thus, some designers often use approximate models, which express the relation between some inputs and outputs. In this paper, we review and compare the complicate metamodels, which are expressed by the interaction of various data through trying many physical experiments and running a computer simulation. The prediction model in this paper employs interpolation schemes known as ordinary kriging developed in the fields of spatial statistics and kriging in Design and Analysis of Computer Experiments (DACE) model. We will focus on describing the definitions, the prediction functions and the algorithms of two kriging methods, and assess the error measures of those by using some validation methods.     

A simple and analytical parameter-extraction method of a microwaveMOSFET

A simple and accurate parameter-extraction method of a high-frequency small-signal MOSFET model including the substrate-related parameters and nonreciprocal capacitors is proposed. Direct extraction of each parameter using a linear regression approach is performed by Y-parameter analysis on the proposed equivalent circuit of the MOSFET for high-frequency operation. The extracted results are physically meaningful and good agreement has been obtained between the simulation results of the equivalent circuit and measured data without any optimization. Also, the extracted parameters, such as g_m and g_ds, match very well with those obtained by DC measurement     

Distribution of bacteria with the arylsulfate sulfotransferase activity

We herein report a simple method using intestinal clamps to prevent intraoperative contamination during an immediate mucocutaneous suture of the intestinal stoma. Using this technique, a protruded intestinal stoma can be constructed reliably without soiling. The technique can be used both for constructing an end as well as a loop intestinal stoma.     

Signal decay through a reverse phosphorelay in the Arc two-component signal transduction system

Escherichia coli senses and signals anoxic or low redox conditions in its growth environment by the Arc two-component system. Under those conditions, the tripartite sensor kinase ArcB undergoes autophosphorylation at the expense of ATP and subsequently transphosphorylates its cognate response regulator ArcA through a His --> Asp --> His --> Asp phosphorelay pathway. In this study we used various combinations of wild-type and mutant ArcB domains to analyze in vitro the pathway for signal decay. The results indicate that ArcA-P dephosphorylation does not occur by direct hydrolysis but by transfer of the phosphoryl group to the secondary transmitter and subsequently to the receiver domain of ArcB. This reverse phosphorelay involves both the conserved His-717 of the secondary transmitter domain and the conserved Asp-576 of the receiver domain of ArcB but not the conserved His-292 of its primary transmitter domain. This novel pathway for signal decay may generally apply to signal transduction systems with tripartite sensor kinases.     

Measuring system for development of stroke-sensing cylinder forautomatic excavator

In order to develop a stroke-sensing cylinder for automatic excavators equipped with Hall sensors of GaAs type, a measuring test facility is set up and used in investigating the design parameters. The measuring system itself is a kind of XZ table with two moving axes in X and Z directions, respectively, on which sensing parts, including Hall sensors, are installed. Furthermore, to attain a high precision of movement of the measuring system, a new sliding mode control is introduced, which diminishes chattering in the control loop by setting two dead zones along the switching line. The unknown parameters for sliding mode control are estimated by a signal compression method. The output signal from a Hall sensor was analyzed by using a measuring instrument. In particular, the detected signal according to the Hall sensor's movement on the piston rod, which has a magnetic scale, was investigated and the vertical distance between the Hall sensor and the piston rod, which gives direct effects on the detected signal, was obtained. Based on these results, the stroke-sensing cylinder was designed and fabricated     

A case study of dissolved air flotation for seasonal high turbidity water in Korea.

A DAF (Dissolved-Air-Flotation) process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when freshwater algae blooms occur or raw water turbidity becomes high. Pre-sedimentation is operated in case when the raw water turbidity is very high due to rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of the raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than the conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while the removal of them by sedimentation is more difficult. One of the main concerns for DAF operation is a high raw water turbidity. DAF is not adequate for raw water, which is more turbid than 100 NTU. In order to avoid this problem, pre-sedimentation basins are installed in the DAF plant to decrease the turbidity of the DAF inflow. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, it is suggested that pre-sedimentation with optimum coagulation prior to DAF is the appropriate treatment scheme.     

Investigation of Domain Wall Velocity to External Fields for High-Quality Waveguide-Type Periodically Poled LiNbO3 Fabrication

The Ti-doped waveguide-type periodically poled LiNbO3 (PPLN) were fabricated and the dependence of domain wall velocity on an external field applied for domain inversion was investigated. The whole polarization reversal process was computer-controlled to regulate domain wall expansion at a feedback time shorter than 5 μs. The coercive voltage and several values of excess voltage were applied on 500 μm-thick wafers serially connected to a 1-MOhm external resistor which had an effect of the poling current reduction, i.e. the deceleration of domain wall expansion. The domain wall velocity is sensitive to the poling voltage, precisely speaking, to the excess voltage. The domain wall velocities were 28.70, 16.02 and 5.75 μm·s-1 under poling field of 23.5, 22.0 and 21.0 kV·mm-1, respectively. Moreover, average duty cycle of PPLN is about 49.93%.