System Development and Performance Testing of a W-Band Gyrotron

A high-power W-band gyrotron has been designed and performance tested in Korea, with an output power in the range of tens of kilowatts. The gyrotron consists of a diode-type electron gun operating at 40 kV, a TE6,2 mode interaction cavity, and a mode converter for producing a highly Gaussian output mode beam. Presented here are the detailed component design procedure and the experimental results of the gyrotron’s performance evaluation. A maximum power of 62 kW was achieved with an efficiency of 22 %, and a highly Gaussian output beam was observed. The gyrotron’s output beam is analyzed, and its transmission through an oversized waveguide is discussed. This gyrotron is the first gyrotron developed in Korea with high power greater than 10 kW and high frequency greater than 90 GHz.     

Predicting the Drop Performance of Solder Joints by Evaluating the Elastic Strain Energy from High-Speed Ball Pull Tests

Despite being expensive and time consuming, board-level drop testing has been widely used to assess the drop or impact resistance of the solder joints in handheld microelectronic devices, such as cellphones and personal digital assistants (PDAs). In this study, a new test method, which is much simpler and quicker, is proposed. The method involves evaluating the elastic strain energy and relating it to the impact resistance of the solder joint by considering the Young’s modulus of the bulk solder and the fracture stress of the solder joint during a ball pull test at high strain rates. The results show that solder joints can be ranked in order of descending elastic strain energy as follows: Sn-37Pb, Sn-1Ag-0.5Cu, Sn-3Ag-0.5Cu, and Sn-4Ag-0.5Cu. This order is consistent with the actual drop performances of the samples.     

Improved reliability of copper-cored solder joints under a harsh thermal cycling condition

This study simulated the performance of Cu-cored solder joints in microelectronic components subjected to the extreme thermal cycling conditions often encountered in the automobile industry by comparing the thermal cycling behavior of Cu-cored solder joints containing two different coating layers of Sn–3.0Ag and Sn–1.0In with that of a baseline Sn–3.0Ag–0.5Cu solder joint under a severe temperature cycling range of ?55 to +150 °C. Both Cu-cored solder joints can be considered a potential solution to interconnects in microelectronic semiconductor packages used under harsh thermal conditions on account of their greater resistance to thermal stress caused by the severe temperature cycling than the baseline Sn–3.0Ag–0.5Cu solder joint.     

Design and analysis of a large-scale multicast output buffered ATMswitch

Proposes and analyzes a recursive modular architecture for implementing a large-scale multicast output buffered ATM switch (MOBAS). A multicast knockout principle, an extension of the generalized knockout principle, is applied in constructing the MOBAS in order to reduce the hardware complexity (e.g., the number of switch elements and interconnection wires) by almost one order of magnitude. In the proposed switch architecture, four major functions of designing a multicast switch: cell replication, cell routing, cell contention resolution, and cell addressing, are all performed distributively so that a large switch size is achievable. The architecture of the MOBAS has a regular and uniform structure and, thus, has the advantages of: (1) easy expansion due to the modular structure, (2) high integration density for VLSI implementation, (3) relaxed synchronization for data and clock signals, and (4) building the center switch fabric (i.e., the multicast grouping network) with a single type of chip. A two-stage structure of the multicast output buffered ATM switch (MOBAS) is described. The performance of the switch fabric in cell loss probability is analyzed, and the numerical results are shown. The authors show that a switch designed to meet the performance requirement for unicast calls will also satisfy multicast calls' performance. A 16×16 ATM crosspoint switch chip based on the proposed architecture has been implemented using CMOS 2-μm technology and tested to operate correctly     

ZnO-Coated TiO2 Nanotube Arrays for a Photoelectrode in Dye-Sensitized Solar Cells

In dye-sensitized solar cells, highly ordered TiO₂ nanotube arrays as a photoelectrode have higher charge collection efficiencies than a nanoparticle-based structure due to their faster charge percolation and slower recombination of electrons. Highly ordered TiO₂ nanotube arrays were grown by anodic oxidation of 0.5-mm-thick titanium foil. To increase the conversion efficiency of dye-sensitized solar cells with TiO₂ nanotube arrays, the surface of the TiO₂ nanotube arrays was modified by zinc oxide thin films. The ZnO thin film was formed by atomic layer deposition. The thin film was conformal on the inner and outer walls of TiO₂ nanotube arrays. ZnO thin film improved the short circuit current (J _sc) and open circuit voltage (V _oc) due to increasing specific surface area from particulates of ZnO thin film and increasing the surface charge induced from the isoelectric point. The power conversion efficiency of dye-sensitized solar cells with ZnO thin film on 4.5-μm-thick TiO₂ nanotube arrays was 1.43%. Microstructure and phase were observed by scanning electron microscopy, x-ray diffractometry, and transmission electron microscopy.     

Cost Effective Silica‐Based 100 G DP‐QPSK Coherent Receiver

We present a cost‐effective dual polarization quadrature phase‐shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two 90° optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of 2%‐Δ. Two four‐channel spot‐size converter integrated waveguide‐photodetector (PD) arrays are bonded on PD carriers for transverse‐electric/transverse‐magnetic polarization, and butt‐coupled to a polished facet of the PLC using a simple chip‐to‐chip bonding method. Instead of a ceramic sub‐mount, a low‐cost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans‐impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3‐dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of is achieved at a 112‐Gbps back‐to‐back transmission with off‐line digital signal processing.     

A Multiobjective Parametric Optimization for Passenger-Car Steering Actuator

A robust design for the size optimization of a motor-driven steer applied in a compact car, using the design of simulation trial, is described and illustrated in this paper. The objective of the optimal design using the combined design of simulation trial and finite-element analysis (FEA) approach is to ensure that the motor-driven steer's performance for compact cars is insensitive to noise, with moderate computational effort. The optimal design process takes into consideration noises that arise in the unexpected load condition, such as tolerances for parameter variation of the electric motor and reduction gear in the actuator. The optimization is realized by a simulation and analysis tool that integrates the Target-wise Parameter Optimization and the FEA. The proposed procedure can not only reduce the size of an actuator but also raise the system efficiency of the motor-driven steering (MDS). In this paper, we have used an orthogonal array ${rm L}18(2^{1} times 3^{7})$ to implement simulation trials and made a response table and graph of control factors. Eventually, the optimal values of the control factors, the diameter of the stator core, the width of the wire, the turn number of the wire, the gear ratio of the worm and worm-wheel gear, the surface flux density of the magnet, the armature core's stack factor, and the module ratio of the worm and worm-wheel gear were decided, and then, the signal-to-noise ratio (SNR) was increased to 20.58%. The simulation results demonstrated that the proposed method applied to the optimal design of the MDS' actuator was feasible and efficient. In this paper, the design optimization process is described, and the results are presented.