• 한국재료학회지
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• 제17권5호
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• pp.289-292
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• 2007

Although piezoelectric bimorph that is using as the sensor in medical and industrial measurement has large displacement, it has problems including efficiency in generating force, energy convergence, and response. Its application is being limited based on the change in resonance frequency with temperature. In this study, to overcome the disadvantages, PZT piezoelectric ceramics was prepared and produced a parallel type piezoelectric bimorphs. In addition, by using the finite element method. the configuration of piezoelectric bimorph was designed and the displacement of the bimorph based on applied electric pressure and the wave pattern were measured. By analyzing the resonance characteristics of the bimorph in the temperature range of $-60{\sim}80^{\circ}C$, an attempt was made to study the operational characteristics and temperature reliability of vortex flowmeter sensor. As a result, the resonance frequency of the bimorph was gradually increased with the temperature from $-60{\sim}80^{\circ}C$. The deflection of the bimorph was found to strongly depend on both the applied electric field waveform and the environmental temperature.

• 소음진동
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• 제11권3호
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• pp.416-421
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• 2001

The flexural vibration of laminated composite beams with an electro-rheological(ER) fluid has been investigated to design a structure with maximum possible damping capacity. The equations of motion are derived for flexural vibrations of symmetrical, mu1ti-layer laminated beams. The damping radio and modal damping of the first bending mode are calculated by means of iterative complex eigensolution method. Finite element method is used for the analysis of dynamic characteristics of the laminated composite beams with an ER fluid. For the validation of modeling methodology using viscoelastic theory the predicted dynamic properties are compared to the measured ones by author's previous work. They are in good agreement. This paper addresses a design strategy of laminated composite under flexural vibrations with an ER fluid.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1998년도 추계학술대회 논문집
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• pp.1-4
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• 1998

In this paper, we have studied a variation of I-V characteristics, and time-dependent dielectric breakdown(TDDB) of thin layer NO and ONO film depending on nitridation and reoxidation time, respectively, and measured a variation of leakage current and charge-to-breakdown(Q$\_$bd/) of optimized NO and ONO film depending on ambient temperature, and then compared with the properties of conventional SiO$_2$. From the results, we find that these NO and ONO thin films are strongly influenced by process time and the optimized ONO film shows superior dielectric characteristics, and Q$\_$bd/ performance over the NO film and SiO$_2$, while maintaining a similar electric field dependence compared with NO layer.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 하계학술대회 논문집 Vol.3 No.2
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• pp.994-997
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• 2002

We have synthesized novel Diphenoquinone(DQ) derivatives. Electron drift mobility of DQ series was measured and electron affinity$(E_a)$ of them is estimated 3.7~3.9eV by CV. Electron drift mobility$(\mu)$ of electric field dependence by time of flight(TOF) technique is $1.76{\times}10^{-5}cm^2/V{\cdot}s$(DQ5) at the concentration of 10wt% verse poly(4,4'-cyclohexylidene diphenylcarbonate)(Pc-Z) and $1.66{\times}10^6V/cm$.

• Journal of Korean Vacuum Science & Technology
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• 제6권1호
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• pp.43-45
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• 2002

We have theoretically investigated steady-state carrier transport and current self-oscillation in negative-effective-mass (NEM) p$\^$+/pp$\^$+/diodes. The current self-oscillation here is a result of the formation and traveling of electric field domains in the p base having a NEM. The dependence of self-oscillating frequency on the applied dc voltage is obtained by detailed numerical simulations. In the calculations, we have considered the scatterings by carrier-impurity, carrier-acoustic phonon, carrier-polar-phonon, and carrier-nonpolar-phonon-hole interactions . This kind of NEM oscillator allows us to reach a current oscillation with terahertz frequency, thus it may be used as a broadband source of terahertz radiation.

• Current Optics and Photonics
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• 제3권6호
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• pp.566-570
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• 2019

To investigate dependence of the sensitivity of THz metamaterials on the position of target dielectric materials, we functionalized the metamaterial gap with an adhesive polymer. A shift in resonance frequency occurs when polystyrene microbeads are deposited in the gap of the metamaterial's metal resonator pattern, while little change is observed when they are deposited on other areas of the metasurface. A two-dimensional mapping of the sensitivity, with a grid size of 1 ㎛, is obtained from a finite-difference time-domain simulation: The frequency shift is displayed as a function of the position of a target dielectric cube. The resulting sensitivity distribution clearly reveals the crucial role of the gap in sensing with metamaterials, which is consistent with the electric field distribution near the gap.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.378-381
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• 2001

The electron drift mobility of poly(4,4'-cyclohexylidenediphenyl carbonate) (PC-Z) doped with 3,5-dimethy-3,5-di-t-butylstilbenequinone(MBSQ), 3,5,3,5-tetra-t-butyl stilbenequinone(TBSQ) and 3,5,3,5-tetra-methyl stilbenequinone(TMSQ) was measured by the time-of-flight technique. The electric field and temperature dependences of the electron drift mobility were discussed with Poole-Frenkel, Arrhenius formulations and non-Arrhenius type of temperature dependence. It was assumed that the hopping sites were Gaussian distribution. Mobility and activation energy of MBSQ were increased with increasing dopant. However, mobilities and activation energy of TBSQ and TMSQ were increased and decreased, respectively.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.508-508
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• 2012

CST microwave studio is used to simulate the plasma profile of the 450mm CCP source. Standing wave effect becomes important at the high frequency as the electrode radius increases. To solve plasma non-uniformity problem, we designed multi electrode chamber to decreasing standing wave effect. Simulation showed the ratio of input power of each electrode is related with electric field strength. The multi electrode was constructed and measured by 2D probe arrays using floating harmonic method. Uniformity of 450 mm CCP was changed by the ratio of input power of each electrode. We described this dependence with circuit model.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 정기총회 및 창립40주년기념 학술대회 학회본부
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• pp.234-238
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• 1987

In this paper, the used specimen composition was added basic additives ($Bi_2O_3\;lmol%$, $Sb_2O_3\;lmol%$, CoO 0.5 mol%, MnO 0.5mol%) to ZnO powder, and $TiO_2$ (1,2,3,4 mol%) to the above basic composition. It appears that there are four regions of conduction current depended upon the strength of the applied electric field ; Ohimic region, Poole-Frenkel region, Schottky region and Tunneling region. Increasing of $TiO_2mol%$, the breakdown voltages of ZnO ceramic varistors are decreased. The decrease of breakdown voltages was explained with the decrease of potential barrier height. Moreover, V-I characteristics with temperature dependence are decreased with increasing of $TiO_2mol%$.

• 한국세라믹학회지
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• 제36권12호
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• pp.1374-1380
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• 1999

The cause of Scond Harmonic Generation (SHG) in thermally poled silica glass is suggested basedon the electrical and dielectric relaxation measurements. The absorption currents as functions of time were measured for various types of silica glasses and analyzed by the theory of Space Charge Polarization. Space charge polarization occurs when an ionic conducting material is subjected to dc electric field with blocking electrode. Thermal poling performed to induce SHG in silica glass is basically identical to the process generating space charge polarization. Hence it was found that gene-ration removal reproduction and temperature dependence of SHG in poled silica is directly related to those of space charge polarization. It turned out that the fundamental parameters governing the SHG in poled silica are charge carrier concentration and mobility. Based on the theory of space charge polarization and experimental results of electrical rela-xation the method to increase the intensity of SHG is proposed.