Abstract In this study, to develop composition ceramics for energy harvesting devices, Pb(Ni_1/3Nb_2/3)O₃-Pb(Zr Ti)O₃ system ceramics substituted with Pb(Mg_1/2W_1/2)O₃ were manufactured by conventional mixed oxide method using Li₂CO₃ and Na₂CO₃ (LNCO) as sintering aids. Their microstructure and piezoelectric properties were also investigated. At the specimen sintered at 930℃, high values of piezoelectric properties appeared: the dielectric constant (εr) of 2,522 planar electromechanical coupling factor kp of 0.602, and k₃₁ of 0.385, d31 = 229 [pC/N], g₃₁ = 10.13 [mV.m/N], Qm of 70, respectively. These values were suitable for the application of devices such as energy harvesting devices and ultrasonic devices.

In-situ analyzation and detection of real-time chemical reactions can be a significant part in interpreting the underlying mechanism in very reactive chemical reactions. To do this, first we have designed a microfluidic device (MFD) pattern for observation of synthesis of hierarchical nanostructures based on graphene oxide (GO), conjugating the well-known coupling reaction by which the solution of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)-mediated coupling is enhanced in the presence of n-hydroxysuccinimide (NHS) to make amide bonding, hereafter called as the EDC coupling. Then, we have manufactured microfluidic devices with multiple tens of micrometer-sized channels that can circulate those nanomaterials to be chemically reacted in the channels. These microfluidic devices were made by negative photo lithography and soft lithography. We showed the possibility of using Raman spectroscopy to reveal the basic mechanism of the energy storage applications.

Magnetoelectric (ME) composites are comprised of magnetostrictive and piezoelectric phases. Lots of theoretical and experimental works have been done on ME composites in the last couple of decades. The output performance of ME composites has been enhanced by optimizing the constituent phases, interface layer, dimensions of the ME composites, different operating modes, etc. However, the detailed information about the characterization of ME coupling in ME composites is not provided yet. Therefore, in this tutorial paper, we are giving an insight into the details of measurements of ME voltage coefficient of ME composites both at off-resonance and resonance conditions. A symmetric type Gelfenol/PMN-PZT/Gelfenol ME composites were fabricated by sandwiching (011) 32-mode PMN-PZT single crystal between two Galfenol plates by epoxy bonding are used for the example of ME coupling measurement. The details about the experimental setup used for the measurement of ME voltage coefficient are provided. Furthermore, a step-by-step measurement of ME voltage coefficient using computerized program is demonstrated. We believe the present experimental measurement details can help readers to understand the concept of ME coupling and its analysis.

Magnetoelectric multiferroics, where a ferromagnetic and a ferroelectric order coexist and are coupled in a single phase, have been a hot topic in condensed matter physics for a long time owing to their ability to facilitate nextgeneration applications. In this review, we briefly introduce basic concept of the magnetoelectric multiferroic oxides as well as their history, physical origins, and significant achievements. The key moments contributing to the progress of magnetoelectric multiferroics are snapshotted chronologically, and then a discussion on the major magnetic exchange interactions and the ferroelectric origins are presented along with their coupling behavior. Furthermore, we argue a need for modifying the present classification of magnetoelectric multiferroics before presenting the evolution of multiferroics using representative examples with their properties such as magnetic/ferroelectric transition temperature, magnetization/electric polarization, and magnetoelectric coefficient. We hope that this brief review will provide the community researchers with insights into magnetoelectric multiferroic oxides.

Metal oxide varistors (MOVs) protect circuits and devices from transient overvoltages in electric power systems. However, a MOV continuously deteriorates owing to manufacturing defects or repetitive protective operations from transient overvoltages. A deteriorated MOV may result in a short circuit or a line-ground accident. Previous studies focused on the analysis of deterioration mechanisms and condition diagnosis techniques for MOVs owing to their recent growth of use. An accelerated deterioration experiment under the same conditions in which a MOV operates is essential. In this study, we designed and fabricated a surge generator that can apply a surge current to a MOV connected to AC mains. The coupling network operates at a low impedance against the surge current from the surge generator and transfers the surge current to the MOV under test. It also acts as a high impedance against AC mains for the AC voltage not to be applied to the surge generator. The decoupling network operates at a high impedance against the surge current and blocks the surge current from AC mains. It also acts as a low impedance against AC mains for the AC voltage to be applied to the MOV under test. The prototype surge generator can apply the 8/20 us up to 15 kA on AC voltages in the approximate range of 110~450 V, and it fully operates on a LabVIEW-based program.

In this study, (1-x)(Na_0.52K_0.443Li_0.037)(Nb_0.883Sb_0.08Ta_0.037)O₃-x(Bi_0.5(Na_0.7K_0.3)_0.5ZrO₃ ceramics were fabricated by BNKZ substitution using a conventional solid-state method to develop excellent lead-free piezoelectric ceramics for piezoelectric actuators; their dielectric and piezoelectric properties were then investigated. All specimens were in the orthorhombic phase. NKL-NSTO₃ ceramics with x=0.01 showed excellent piezoelectric properties. The density (ρ), piezoelectric charge constant (d₃₃), planar piezoelectric coupling coefficient (k_p), mechanical quality factor (Q_m), and dielectric constant (ε_r) had optimized values of 4.56 g/㎤, 208 pC/N, 0.43, 96, and 975, respectively.

Because of a waveguiding effect and total internal reflection caused by a difference inrefractive indices, only 20% of generated light is emitted to the air and the rest is trapped or absorbed inthe device. An improvement of outcoupled efficiency of organic light-emitting diodes was studied using amicrolens array. Mold of microlens array was fabricated by using photo-lithography with the AZ9260photoresist, and the microlens array was formed onto the glass substrate using the UV curing agentnamed ZPU13-440. Device structure consists of microlens/glass/ITO/TPD/Alq3/LiF/Al. It was found thatthere is an improvement of external quantum efficiency by about 20% at the same current density for thedevice with the microlens array compared to that of the reference one. Simulated outcoupled efficiencyshows the improvement by about 20% for the device with the microlens array compared to that of thereference one. These results are consistent with the experimental ones

In this paper, a measurement method to obtain the optical properties of a liquid base on a side-polished single mode fiber was proposed and demonstrated. The device showed periodic resonance coupling against wavelengths. The refractive index and dispersion characteristics of a liquid were calculated by use of the spacings of periodic resonance wavelengths of the device. The thermo-optic coefficient of the liquid was obtained by monitering the shift of resonance wavelengths of the devices with change of environmental temperature.

In this paper, PZT piezoelectric ceramic specimens with 4 compositions (Zr/Ti=50/50, 53/47, 56/44, 58/42) in Pb(Zr,Ti)O3 system were fabricated. We studied effects of poling strength and thermal aging on the temperature characteristics of eletromechanical coupling factor k31 of the specimens, which were poled with the DC electric fields, 1.5, 2.5 and 3.5 kV/mm respectively and thermally aged for an hour at 200℃. The eletromechanical coupling factor k31 of the specimen with the composition Zr/Ti=53/47, nearest to the morphotropic phase boundary decreased the most greatly, irrelevant to the intensity of poling field, due to 1st thermal aging. And the temperature coefficient of eletromechaical coupling factor k31 was(-) in the ereragonal phase composition and (+) in the rhombohedral phase composition, which is reverse in the temperature coefficient of resonance frequency. It is interesting that eletromechanical coupling factor k31 of PZT ceramics is shown to be able to be able to increase as temperature increase in the interval -20~80℃.

In this study, we introduce a polymer(polyimide) based pressure sensor to measure real-time heart beat and blood pressure. The sensor have been designed with consideration of skin compatibility of material, cost effectiveness, manufacturability and wireless detection. The designed sensor was composed of inductor coils and an air-gap capacitor which generate self-resonant frequency when electrical source is applied on the system. The sensor was obtained with metalization, etching, photolithography, polymer adhesive bonding and laser cutting. The fabricated sensor was shaped in circular type with 10mm diameter and 0.45 mm thickness to fit radial artery. Resonant frequencies of the fabricated sensors were in the range of 91∼96 MHz on 760 mmHg pressurized environment. Also the sensor has good linearity without any pressure-frequency hysteresis. Sensitivity of the sensor was 145.5 kHz/mmHg and accuracy was less than 2 mmHg. Real-time heart beat measurement was executed with a developed hand-held measurement system. Possibility of real-time blood pressure measurement was showed with simulated artery system. After installation of the sensor on skin above radial artery, simple real blood pressure measurement was performed with 64 mmHg blood pressure variation.

Abstract: We focused on the development of red azo colorants with high thermal stability and good solubility for LCD color filter in this research. For the synthesis of hybrid azo colorants, we used the couplers of aniline. naphthol and benzoimidazol functional group. The synthesized hybrid azo colorants were charaterized by using NMR, UV/visihle spec troscopy, FT - JR. EA and 1`GA. They represented the maximum absorption wavelengths which are longer than 500 urn in UV/visible spectrum. So they were confirmed to be suitable for red colorants of LCD color filter. Azo compound (la, lh) with aniline functional group had good soluhility in organic solvents such as acetone, methanol, chloroform and PGMEA. Moreover azo compounds (ic, id and Ic) with naphthol and benzoimidazolone functional group gave excellent thermal stability higher than 250t in TGA thermograms.

Recently, micro cavity is studied to reduce the optical loss of BLU and OLED. In this paper, we suggest applying micro cavity to photo-luminescent lamp with plasma discharge technology to meet the display applications for a BLU for LCD. The structure of photo-luminescent lamp consists of SUS foil and ITO glass with micro cavity. The op to-elect riccharacteristics of photo-luminescent lamp with micro cavity was evaluated. The brightness of photo-luminescent device was increased over 111 ccVm2 with the adaptation of patterned micro cavity at 30 pm. The 3D optical simulation verified the enhanced light out coupling when micro cavity applied to the device.

In this study, lead-free (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 ceramics were fabricated by conventional mixed oxide method. Structural and electrical properties of lead-free (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 ceramics with the variation of sintering temperature were investigated. As results of x-ray diffraction analysis, all specimens showed a typical polycrystalline perovskite structure without presence of the second phase. Sintered density increased with an increases of sintering temperature and the specimen sintered at 1,020℃ showed the maximum value of 4.5 g/cm3. The average grain size of the (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 specimen sintered at 1,020℃ is about 0.83 μm. Electromechanical coupling factor, relative dielectric constant and dielectric loss of (Na0.465K0.465Bi0.07)(Nb0.93Ti0.07)O3-0.08MnO2 specimens sintered at 1,020℃ were 0.252, 741 and 0.043% respectively.

Recently, Near-infrared (NIR)colorant is intriguing and attractive but full of challenges. Although some cyanine colorant have been commercialized, near-infrared colorant with intensive NIR absorption, good chemical and photo-stability, and high solubility still remain as target compound. Certain polycyclic aromatic compounds such as quaterrylene represent a key class of NIR colorant and also give rise to outstanding physical and chemical properties after appropriate chemical modification. In this study, We have tried to introduce imide functional group to quaterrylene in order to give chemical and thermal stability. Finally, N,N`-bis (2,6-diisopropylphenyl)-quarterrylene-3,4:13,14-tetracarboximide was synthesized and evaluated its properties using 1H NMR, Maldi-tof, TGA, and UV/VIS/NIR spectroscopy as NIR colorant. The quaterrylene bisimide compound exhibit a excellent thermal stability and chemical stability.

In this study, lead-free (K0.5Na0.5+X)(Nb0.96Sb0.04)O3+0.2mol%La2O3+1.2mol% K4CuNb8O23 (X= 0∼0.025) ceramics were fabricated by normal sintering method at 1060℃ for 5 h. Microstructures, piezoelectric and dielectric properties of specimens were investigated with special emphasis in the influence of Na excess addition. The grain size of specimen was slightly decreased with increasing Na content. In the 2 [mol%] Na excess addition of NKNS ceramics, density, electromechanical coupling factor, piezoelectric constant and electromechancal quality factor of specimen were found to reach the optimum values of 4.25 [g/cm3], 0.4357, 154.43 [pC/N] and 580, respectively.

Abstract: (K(0.5)Na(0.5)) (Nb(0.96)Sb(0.04)) O(3)+1.2 mol% K(4)CuNb(8)O(23) ceramics doped with iron oxide (Fe(2)O(3)) were prepared by a conventional mixed oxide method. And then, their piezoelectric and dielectric properties were investigated as a function of Fe(2)O(3) addition. X-ray diffraction studies reveal that Fe(3+) diffuses into the NKN lattices to form a solid solution with a pure perovskite structure at room temperature. At the sintering temperature of 1,060℃, when 0.2 mol% Fe(2)O(3) was doped, the piezoelectric constant (d(33)), electromechanical coupling factor (Kp), and mechanical quality factor (Qm) showed the excellent values of 131.67 pC/N, 0.436, and 696.36, respectively. Results show that Fe(2)O(3) deped (K(0.5)Na(0.5))(Nb(0.96)Sb(0.04))O(3)+1.2 mol% K(4)CuNb(8)O(23) lead-free piezoelectric ceramics are a promising lead free material for piezoelectric transformer applications.