• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.163-168
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• 2006

In a micro-unit of electronic-machine, vibration can be excited by a small impact, and this vibration acts as a fatigue load. To measure the vibration effect on the micro unit, a micro dynamic tester is needed to test a micro specimen. In this paper, it has confirmed a movement of the PZT(piezo actuator) to use a sine signal. And, it has confirmed a fracture of specimens by using a tension-tension input signal in PZT. A metal-material property in the micro scale has been tested to compare with the macro scale. A fatigue test has been conducted by using PZT actuator to give a bending-tension effect.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.1047-1051
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• 2004

Charge amplifier systems benefit from the very wide dynamic range of PE accelerometers by offering flexibility in adjusting the electrical output characteristics such as sensitivity and range. They are well suited for operation at high temperatures. Modern charge systems feature improved low noise operation, simplified digital controls, and dual mode operation for operation with charge or IEPE voltage mode sensors. high impedance circuitry is not well suited for operation in adverse field or factory environments. The resolution of a PE accelerometer may not be specified or known since noise is a system consideration determined by cable length and amplifier gain. IEPE accelerometrs operate from a constant current power source, provide a high-voltage, low-impedance, fixed mV/g output. They operate through long, ordinary, coaxial cable in adverse environments without degradation of signal quality. They have limited high temperature range. IEPE sensors are simple to operate. Both resolution and operating range are defined specifications. Cost perchannel is lower compared to PE systems since low-noise cable and charge amplifiers are not required.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.315-319
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• 2021

Recent impact of 4th industrial revolution is increasing usage of IoT technology along with smartphones and tablet PC. However blue light emitted from electronic devices such as smartphones and tablet PC causes detrimental change to human bodies. As the controversy over the harmfulness of blue light became known through the media and various communities, related markets were formed, and various blocking films, software, and vision protection monitors were released. In this paper focuses on utilizing IoT technology to protect human organizations from blue light. It presents anti-blue light system which prevents excessive exposure to blue light through Arduino module such as ultrasound, piezo buzzer and blue light measurement module.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.1
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• pp.83-90
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• 2014

EHD (electro-hydro-dynamics) patterning was performed under atmospheric pressure at room temperature in a single step. The drop diameter smaller than nozzle diameter and applied high viscosity conductive ink in EHD patterning method provide a clear advantage over the piezo and thermal inkjet printing techniques. The micro electrode pattern was printed by continuous EHD patterning method using 3-type control parameters (input voltage, patterning speed, nozzle pressure). High viscosity (1000cps) conductive ink with 75wt% of silver nanoparticles was used. EHD cone type nozzle having an internal diameter of $50{\mu}m$ was used for experimentation. EHD jetting mode by input voltage and applied 1st order linear regression in stable jet mode was analyzed. The stable jet was achieved at the amplitude of 1.4~1.8 kV. $10{\mu}m$ micro electrode pattern was created at optimized parameters (input voltage 1.6kV, patterning speed 25mm/sec and nozzle pressure -2.3kPa).

• Journal of Sensor Science and Technology
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• v.5 no.3
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• pp.65-73
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• 1996

One of the important factor in drug stuffs to a patient is to inject exact amount with stable flow rates. Since improper injection amount and flow rates would cause bad effect to recovery of a patient, the detecting sensors with high sensitivity is required for an injection pump systems' performance improvement. In this study, the three sensors, piezo film sensor, photo transistor and photo array, were compared to find best one for an injection pump monitoring system. Using suggested data processing technique and photo array sensors, we could minimize the effect of interference, disturbance, illumination, and sensitivity change caused by sensor's position. According to the experiments, the photo array showed the higher reliance than any other the three types of sensors.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.12
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• pp.955-960
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• 2012

We fabricated piezoelectric unimorph cantilever generators (UCG) using $Pb(Zr_{0.54}Ti_{0.46})O_3$ + 0.2 wt% $Cr_2O_3$ + 1.0 wt% $Nb_2O_5$ (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 $mW/cm^3$) 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.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.6
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• pp.122-128
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• 2016

The Biosensor biosensor pattern was developed by via an EHD (electro-hydro-dynamics (EHD) patterning process that was performed under atmospheric pressure at room temperature in a single step. The drop diameter was smaller than nozzle diameter and applied high viscosity conductive ink was applied in the EHD patterning method to provide a clear advantage over the piezo and thermal inkjet printing techniques. The Biosensor's biosensor's micro electrode pattern was printed by via a continuous EHD patterning method using 3three- type types of control parameters parameter (input voltage, patterning speed, nozzle pressure). High viscosity (1000 cps) conductive ink with 75 wt% of silver nanoparticles was used for experimentation. The incremental result of impedance of biosensor impedance was measured between the antibody ($10ug{\mu}g/ml$) to spore (0.1 ng/ml, 10 ng/ml, and $1ug{\mu}g./ml$) reaction at frequency 493 MHz frequency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.4
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• pp.648-655
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• 2019

This paper proposes the differential development of a Taekwondo electronic body protector. For this development, the most suitable sensor system was selected after analyzing and testing various sensor methods (magnetic sensors, electric capacity sensors, contact switch sensors, and piezo-film sensors) that could be applied in the electronic body protector, the selected sensors were distributed to the body and feet to make a more precise hit score, unlike the existing system in which all sensors are centralized on the body. Furthermore, it aims to illuminate using a lightweight film-type piezoelectric sensor on the body protector. In the case of an existing electronic body protector, all sensors and network device were concentrated on the body protector, so users need to purchase a set if they want it. On the other hand, the proposed system cloud can be used individually using a smart scoring WEP program. The effects of decreasing weight by up to 20% were compared with those of the existing system. Setting up a test facility is very difficult, so more study will be needed to analyze the effects of a hit.

• Ceramist
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• v.23 no.1
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• pp.54-88
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• 2020

Global effort has resulted in tremendous progress with energy harvesters that extract mechanical energy from ambient sources, convert it to electrical energy, and use it for systems such as wrist watches, mobile electronic devices, wireless sensor nodes, health monitoring, and biosensors. However, harvesting a single energy source only still pauses a great challenge in driving sustainable and maintenance-free monitoring and sensing devices. Over the last few years, research on high-performance mechanical energy harvesters at the micro and nanoscale has been directed toward the development of hybrid devices that either aim to harvest mechanical energy in addition to other types of energies simultaneously or to exploit multiple mechanisms to more effectively harvest mechanical energy. Herein, we appraise the rational designs for multiple energy harvesting, specifically state-of-the-art hybrid mechanical energy harvesters that employ multiple piezoelectric and triboelectric mechanisms to efficiently harvest mechanical energy. We identify the critical material parameters and device design criteria that lead to high-performance hybrid mechanical energy harvesters. Finally, we address the future perspectives and remaining challenges in the field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.06a
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• pp.433-433
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• 2009

ZnO-based materials have been extensively studied for optoelectronic applications due to their superiors physical properties such as wide direct bandgap (~3.37 eV), large exciton binding energy (~60 meV), high transparency in the visible region, and low cost. Especially, one-dimensional (1D) ZnO nanostructures have attracted considerable attention owing to quantum confinement effect and high crystalline quality. Additionally, various nanostructures of ZnO such as nanorods, nanowires, nanoflower, and nanotubes have stimulated the interests because of their semiconducting. and piezoelectric properties. Among them, vertically aligned ZnO nanorods can bring the improved performance in various promising photoelectric fields including piezo-nanogenerators, UV lasers, dye sensitized solar cells, and photo-catalysis. In this work, we studied the effect of the annealing temperature of homo seed layers on the formation of ZnO nanorods grown by hydrothermal method. The effect of annealing temperature of seed layer on the length and orientation of the nanorods was investigated scanning electron microscopy investigation. Transmission electron microscopy and X-ray diffraction measurement were performed to understand the effect of annealing temperatures of seed layers on the formation of nanorods. Moreover, the optical properties of the seed layers and the nanorods were studied by room temperature photoluminescence.