Kyoung-Bum Kim

An ultra low power CMOS motion detector

This paper proposes a CMOS motion detector which consumes extremely low power. CMOS image sensor pixels in this motion detector senses image and image data are converted into just one-bit by using clocked comparators. Because using one-bit data makes additional processing units simple, total power consumption of this CMOS motion detector can be reduced. That is, internal memory which is composed of the clocked gating schemes based on the flip-flop and XOR function which compares a current image with a previous one in order to detect a difference are main features for the simple structure. However one-bit data process has a critical problem that it is hard to detect a motion when image inclines to white or block. For solving this problem, reference voltage controller which makes about the same proportion of white and block is implemented. We have made a test module of the proposed CMOS motion detector and tested it by using FPGA. According to the measurement result, total power consumption is about 32 ¿W at 3.3 V. Therefore, this motion detector can be useful for portable battery-operated devices.

Energy Harvesting Characteristics of Spring Supported Piezoelectric Cantilever Structure (SPCS)

Spring supported piezoelectric cantilever structures (SPCS) were fabricated for vibration-based energy harvester application. We selected four elastic springs (A, B, C, and D type) as cantilever`s supporter, each elastic spring has a different spring constant (S). The C type of SPCS (: 4,649 N/m) showed a extremely low resonance frequency of 81 Hz along with the highest power output of 38.5 mW while the A type of SPCS (: 40,629 N/m) didn`t show a resonance frequency while. Therefore, it is considered that the lower spring constant lead to a lower resonance frequency of the SPCS. In addition, a tip mass (18 g) at one end of the SPCS could further reduce the resonance frequency without heavy degradation of power output.

Surveillance camera SOC architecture using one-bit motion detection for portable applications

This paper presents a single chip architecture using a one-bit motion detection algorithm and its applications and user interfaces. The proposed motion-detection algorithm uses just one-bit images, which are selected by binary search algorithm for finding the proper reference. A conventional surveillance system requires many components and has been too complicate for portable applications. In this paper, we present a simple architecture and a motion detector that can detect the change of an object surrounding in order to realize low power and low cost. We present the experimental results and verify all functions from motion detection to an user interface program on FPGA board.

Optimization of the Unimorph Cantilever Generator (UCG) Using Pb(Zr 0.54 Ti 0.46 )O 3 + 0.2 wt% Cr 2 O 3 + 1.0 wt% Nb 2 O 5 thick films

We fabricated piezoelectric unimorph cantilever generators (UCG) using + 0.2 wt% + 1.0 wt% (PZCN) piezoelectric thick films, which were produced by a tape casting method. The PZCN thick films were tailored with same width and thickness but different lengths from 7.7 to 57.7 mm in order to evaluate optimized UCG for energy harvesting device applications. When the length of PZCN film was increased, the resonance frequency of UCG was slightly increased from 7 Hz to 8 Hz, which could be due to enlarged area of the highly stiff piezo-ceramic film. However, the output power was proportionally increased with the length of PZCT film and it reached 4.68 mW (1.221 ) when the film`s length was 57.7 mm under 25 g of tip mass at 8 Hz, which is sufficient for micro-scale device applications.

Effect of Pd Reactant on One-Dimensional Growth of ZnO on Si Substrate by Thermal Evaporation Method

ZnO nanostructures were developed on a Si(100) substrate from the powder mixture of ZnO and x mol % Pd (ZP-x) as reactants using a thermal evaporation method. The effect of Pd on the growth characteristics of one-dimensional ZnO nanostructures was investigated. High temperature X-ray diffraction patterns obviously revealed that Pd assisted the reduction of ZnO at temperatures higher than 1000 °C. Needle-like ZnO nanorod array, developed from ZP-x (x≥2) mixture, was well aligned vertically on the Si substrate at 1100 °C while nano-crystalline ZnO layer was only obtained from pure ZnO powder. Thus, it is considered that Pd is responsible for the growth of ZnO nanorod on the Si substrate at 1100 °C by providing the Zn vapor for the Zn/ZnOx droplets with reducing ZnO in the reactant. The developed ZnO nanorod exhibited growth direction along [001] with defect-free high crystallinity.

Fabrication and Energy Harvesting Characteristics of Water Energy Harvester Using Piezoelectric Ceramic Bimorph Cantilever

A new water energy harvester module, which is composed of piezoelectric bimorph cantilevers, harvesting circuit and a shaft with 16 impellers at a center axis, was fabricated for energy harvesting application. High energy density Pb(Zr0.54Ti0.46)O3 + 0.2 wt% Cr2O3 + 1.0 wt% Nb2O5 (PZT-CN) thick film obtained by tape casting method was used for the bimorph cantilever. The PZT-CN bimorph cantilever with a proof mass of 49 g exhibited extremely high output power of 22.5 mW (24 mW//cm 3 ) at resonance frequency of 11 Hz. In addition, the fabricated water energy harvester has a cylindrical structure with 48 bimorph cantilevers clamped at inner surface. A significantly high output power of 433 mW was obtained at a rotation speed of 120 rpm with a resistive load of 500 Ω for the water energy harvester.

Investigation on Growth Characteristic of ZnO Nanostructure with Various O 2 Pressures by Thermal Evaporation Process

ZnO nanostructures were developed on a Si (100) substrate from powder mixture of ZnO and 5 mol% Pd (ZP-5) as reactants by sccm oxygen pressures(x

Enhancement of PTCR Characteristics of MnO 2 Doped Lead Free BaTiO 3 -(Bi 0.5 Na 0.5 )TiO 3 Ceramics with High T c (>165℃)

0.935Ba-0.065() (BBNTM-x) ceramics with were fabricated with muffled sintering by a modified synthesis process. Their microstructure and enhanced positive temperature coefficient of resistivity (PTCR) characteristics were systematically investigated in order to obtain lead-free high TC PTCR thermistors. All specimens showed a perovskite structure with a tetragonal symmetry and no secondary phase was observed. Grain growth was achieved when the doped MnO2 was increased above 0.02 mol%. This is due to the effect of positive Mn ion doping as an acceptor compensating a Ba vacancy occurred by the higher donor dopant concentration of ion. Especially, enhanced PTCR characteristics of the extremely low of , PTCR jump of , of 15.5%/ and high of were achieved for the BBNTM-0.04 ceramics.

Growth, Structural and Optical Properties of c-axis Oriented ZnO Nanorods Array by Hydrothermal Method

ZnO nanorods array have been grown on the seed crystal coated Si(100) substrate by hydrothermal method. The growth, structural and optical properties of ZnO nanorods array were investigated with a variation of precursor concentration from 0.01 M to 0.04 M. The array density of grown ZnO nanorods per same area was increased with increasing the concentration of precursor solution. Vertically aligned ZnO nanorods with hexagonal wurtzite structure have highly preferred c-axis orientation along (002) lattice plane. Especially, ZnO nanorods array developed from 0.04 M precursor solution showed a diameter of about 85 nm and length of 1.2 without any crystallographic defects. The photoluminescence spectra of ZnO nanorods from heavier precursor concentration exhibited stronger UV emission around 380 nm corresponding with near-band-edge emission.

Investigation on PTCR Characteristics of (1-x)BaTiO 3 -x(Bi 0.5 Na 0.5 )TiO 3 (0.01≤x≤0.10) Ceramics by Modified Synthesis Process

() ceramics were fabricated with muffled sintering by a modified synthesis process. Their positive temperature coefficient of resistivity (PTCR) characteristics were investigated systematically. All specimen showed a perovskite structure with a tetragonal symmetry. Both the lattice parameter of a and c axes were slightly decreased with increasing (BNT) content. Grain growth was achieved when the incorporated BNT was increased to 6 mol% and the inhibition of grain growth is considered to be due to the appearance of Ba vacancy () in the (). With 4 mol% BNT addition, room temperature resistivity decreased to and a resistivity jump () was as high as , respectively. Curie temperature was also increased to with increasing BNT content.