• Proceedings of the Materials Research Society of Korea Conference
• /
• 2012.05a
• /
• pp.66.1-66.1
• /
• 2012

Although all printed cost-less radio frequency identification (RFID) tags have been considered as a core tool for bringing up a ubiquitous society, the difficulties in integrating thin film transistors (TFTs), diodes and capacitors on plastic foils using a single in-line printing method nullify their roles for the realization of the ubiquitous society1,2. To prove the concept of all printed cost-less RFID tag, the practical degree of the integration of those devices on the plastic foils should be successfully printed to demonstrate multi bit RFID tag. The tag contains key device units such as 13.56 MHz modulating TFT, digital logic gates and 13.56 MHz rectifier to generate and transfer multi bit digital codes via a wireless communication (13.56 MHz). However, those key devices have never been integrated on the plastic foils using printing method yet because the electrical fluctuation of fully printed TFTs and diodes on plastic foils could not be controlled to show the function of desired devices. In this work, fully gravure printing process in printing 13.56 MHz operated 32 bit RFID tags on plastic foils has been demonstrated for the first time to prove all printed RFID tags on plastic foils can wirelessly generate and transfer 32 bit digital codes using the radio frequency of 13.56 MHz. This result proved that the electrical fluctuations of printed TFTs and diodes on plastic foils should be controlled in the range of maximum 20% to properly operate 32 bit RFID tags.

• Korean Journal of Optics and Photonics
• /
• v.12 no.4
• /
• pp.300-304
• /
• 2001

We suggest a method to measure and correct bending deformation in piezoelectric ceramics displacement. The angle and direction of the bending deformation are measured by monitoring the position of a laser beam reflected on a mirror which is attached to the piezoelectric ceramics with the uncertainty of the angle measurement of $0.36\mu$rad. We divided the electrode of a piezoelectric ceramic into 3 parts and connected 3 capacitors to each electrode in order to apply different voltage to each electrode with one voltage supplier. The deformation was corrected by adjusting the capacitance of each capacitor and was reduced to 6.3%, comparing to the uncorrected case. By using this corrected piezoelectric ceramic to modulate the length of the ringdown cavity, the fluctuation of the decay time caused by the change in optic axis of the cavity was removed.emoved.

• Journal of the Korean Magnetics Society
• /
• v.2 no.1
• /
• pp.69-74
• /
• 1992

This paper describes the energy and speed characteristics of an induction coil-gun. The coil-gun has some merits that it can be easily installed and repeatedly used many times, it does not damage mechanically in the course of launch and the force exerted on the projectile is distributed uniformly. An equivalent circuit is employed for modeling the coil-gun. The circuit equations and equation of motion are then derived based on the equivalent circuit. These equations are solved numerically by using Runge-Kutta method. Finally the energy transfer ratios are obtained according to the variations of the resonant frequency of driving circuit and charging voltage of capacitors. The muzzle velocities of projectile are also obtained according to the variations of electrical conductivity and initial position of projectile, firing angle of driving circuit, charging voltage of capacitor and resistance of driving coil, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.295-295
• /
• 2013

Supercapacitors with higher energy and power density are attracting growing attention for their wide range of potential applications such as portable electronic equipments, hybrid vehicle and cellular devices. In various classes of materials for supercapacitors, the redox pseudocapacitive materials such as conducting polymers and metal oxides have been most widely studied recently. The nanostructuring of the electrode surface has also been focused on since it can provide large surface area and consequently easy diffusion of ions in the capacitors. Among the active materials, in this work, we have used polyaniline (PANi) and manganese oxide ($MnO_2$). PANi is one of the promising electrode and active materials due to its desirable properties such as high electrochemical activity, high doping level and stability. $MnO_2$ is also widely studied material for supercapacitors since it is relatively cheap and environmentally friendly. In this work, we fabricated PANi hollow nanospheres by polymerizing aniline monomers on the polystyrene (PS) nanospheres and then dissolving the inner PS spheres. This nanostructuring of the PANi surface can provide large surface area and hence easy diffusion of electrolyte ions. We also incorporated $MnO_2$ nanoparticles into the PANi hollow nanospheres and investigated its electrochemical properties. It is expected that the combination of these two active materials with slightly different working potential windows show synergetic effects such as broader working potential range and enhanced specific capacitance.

• Journal of Power Electronics
• /
• v.16 no.6
• /
• pp.2258-2271
• /
• 2016

In this paper, some crucial performance characteristics related to the operational reliability of the post-fault Pulse Width Modulated (PWM) rectifiers, such as line current harmonic distortion, Common Mode Voltage (CMV), and current stress on the capacitors, are fully investigated. The aforementioned performance characteristics of post-fault rectifiers are highly dependent on the utilized space vector modulation (SVM) schemes, which are also examined. Detailed analyses of the three most commonly used SVM schemes for post-fault PWM rectifiers are provided, revealing the major differences in terms of the zero vector synthesis approaches. To compare the performances of the three SVM schemes, the operating principles of a post-fault rectifier are presented with various SVM schemes. Using analytical and numerical methods in the time domain, the performances of the line current distortion, common mode voltage and capacitor current are evaluated and compared for each SVM scheme. The proposed analysis demonstrates that the zero vector synthesis approaches of the considered methods have significant impacts on the performance characteristics of rectifiers. In addition, the advantages and disadvantages of the proposed SVM schemes are discussed. The experimental results verify the effectiveness and validity of the proposed analysis.

• International Journal of Railway
• /
• v.4 no.1
• /
• pp.12-18
• /
• 2011

The ATS system is used to provide wayside signaling. Currently, the oscillation frequency is set at 78[kHz] in the normal state. As the on-board receiver crosses over the wayside transmitter, the oscillation frequency is changed by capacitors of the wayside transmitter in a manner dependent on the train speed. As the oscillation frequency is changed, the waveform is modified in the wayside transmitter as well as in the on-board receiver. When there are other signal systems such as a ATO system present near the wayside transmitter, frequency interference occurs. This phenomenon arises since other signals or communication frequencies present will be included in the waveform. Trains often stop due to these other frequencies included in the waveform. In this paper, a model of the interaction between the wayside transmitter and on-board receiver is suggested and frequency response in the wayside transmitter and on-board receiver in the presence of the other signals are estimated by the coupling coefficient. Also, the coupling coefficients are estimated, and the optimal value is proposed.

• Journal of the Korean Society for Railway
• /
• v.15 no.2
• /
• pp.116-121
• /
• 2012

DC/DC switching power converters produce DC output voltages from different DC input sources. The converter is used in regenerative braking of DC motors to return energy back in the supply, resulting in energy savings for the systems containing frequent stops. The DC/DC converter is composed of a PWM-IC (pulse width modulation integrated circuit) controller, a MOSFET (metal-oxide semi-conductor field-effect transistor), an inductor, capacitors, and resistors, etc. PWM is applied to control and regulate the total output voltage. In this paper, radiation shows the main influence on the changes in the electrical characteristics of comparator, operational amplifier, etc. in PWM-IC. In the PWM-IC operation, the missing pulses, the changes in pulse width, and the changes of the output waveform are studied by the simulation program with integrated circuit emphasis (SPICE) and compared with experiments.

• ETRI Journal
• /
• v.39 no.6
• /
• pp.874-879
• /
• 2017

This paper challenges the fabrication of a thin film energy storage device on a flexible polymer substrate specifically by replacing most commonly used metal foil current collectors with coated current collectors. Mass-manufacturable spray-coating technology enables the fabrication of two different half-cell electric double layer capacitors (EDLC) with a spray-coated silver paste current collector and a Ni foil current collector. The larger specific capacitances of the half-cell EDLC with the spray-coated silver current collector are obtained as 103.86 F/g and 76.8 F/g for scan rates of 10 mV/s and 500 mV/s, respectively. Further, even though the half-cell EDLC with the spray-coated current collector is heavier than that with the Ni foil current collector, smaller Warburg impedance and contact resistance are characterized from Nyquist plots. For the applied voltages ranging from -0.5 V to 0.5 V, the spray-coated thin film energy storage device exhibits a better performance.

• Journal of the Korean Institute of Telematics and Electronics B
• /
• v.31B no.8
• /
• pp.20-30
• /
• 1994

The lossless bounded real(LBR) two-pair cascade structure is one of the exiting low-sensitivity digital filter structures such as wave digital filters(WDFs) orthogonal filters. They are known to have the same structures which are composed of canonic building blocks interconnected to each other. The LBR two-pair cascade filters amount to describing in a unified manner the existing canonic low-sensitivity filters in terms of transfer matrices and chain matrices. However the existing structures have somewhat degraded low-sensitivity performance because they include dependent parameters within their structures. In this paper we propose a filter structure called “two-type-interlaced(TTI) structure.” eliminating such problem completely. This structures can be viewed as the WDFs of analog ladder circuits. As ladder circuits are obtained by cascading Brune sections and merging neighboring inductors or capacitors. so TTI structures at e obtained by cascading Type 3 LBR two-pairs and merging neighboring Type 1 LBR two-pairs. Next, a test procedure called “LBR test” is also presented in this paper. which determines whether of not the quantized TTI structure is stable . If it is unstable we can fine-tune the quantized parameters to make the overall structure stable. Therefore we can solve the dependent parameter problem completely with TTI structure along with LBR test. test.

• IEIE Transactions on Smart Processing and Computing
• /
• v.2 no.4
• /
• pp.248-254
• /
• 2013

The size and power consumption of digital circuits including the dimming circuit part will increase for high-performance solid state lighting (SSL) systems in the future. This study examined the low-power consumption of adiabatic dynamic CMOS logic (ADCL) due to the principles of adiabatic charging. Furthermore, the designed low-power ADCL digital pulse width modulation (PWM) was optimized for SSL dimming systems. For this purpose, an ADCL digital 3-bit PWM was optimized in two steps. In the first step, the architecture of the ADCL digital 3-bit PWM was miniaturized. In the second step, the clock cut-off circuit was designed and added to the ADCL PWM. As a result, compared to the original configuration, 60 transistors and 15 capacitors of ADCL digital 3-bit PWM were reduced for miniaturization. Moreover, the clock cut-off circuit, which controls wake-up and sleep mode of ADCL D-FFs, was designed. The power consumption of an optimized ADCL digital PWM for all bit patterns decreased by 54 %.