• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.11a
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• pp.34-37
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• 1992

In this paper, the $(SrPb)(CaMg)TiO_3$-xBi_2O_3{\cdot}3TiO_2$ ceramics with paraelectric properties were fabricated by the mixed oxide method. In order to investigate the behavior of charged particles, the characteristics of electrical conduction and thermally stimulated current were measured respectively. As a result on characteristics of the electrical conduction, the leakage current was increased as measuring temperature was increased. At room temperature, the conduction current was divided into the three steps as a function of DC electric field. The first step was Ohmic region due to ionic conduction, below 15[kV/cm]. The second step was showed a saturation which seems to be related to a depolarizing field occuring in field-enforced ferroelectric phase, between 15[kV/cm] and 40[kV/cm]. The third step was attributed to Child's law related to spare charge which injected from electrode, above 40[kV/cm]. Thermally stimulated currents(TSC) spectra with various biasing fields exhibited three distinguished peaks that were denoted as ${\alpha}$, ${\alpha}'$ and ${\beta}$ peak, each of which appeared at nearby -30, 20 and 95[$^{\circ}C$] respectively. It is confirmed that the a peak was due to trap electron trapped in the grainboundary, and ${\alpha}'$ peak that was observed above only 1.5[kV/mm] was attributed to field-enforced ferroelectric polarization. The origin of ${\beta}$ peak was identified as ion migration which caused the degradation.

• Journal of Embryo Transfer
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• v.11 no.3
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• pp.259-269
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• 1996

The present study was undertaken to examine the critical effect of $Ca^2$+ concentration on electrostimulation and post-electrostimulation media for electric activation of in vitro matured oocytes of Korean Native Cattle. Oocytes collected from slaughterhouse ovaries were matured in TCM 199 containing FSH, estradiol-17$\beta$ and FBS with granulosa cell monolayer for 24 hours and denuded with hyaluronidase. And then cumulus-free oocytes were submitted to a DC field of 1.0 kV/cm for 60 $\mu$sec in electroporation media(0.28 M mannito' and PBS) with different $Ca^2$+ concentations (0.00, 0.05, 0.10 and 0.15 mM). Stimulated oocytes were stained and examined for pronuclear formation after incuhation in SOF for 12 hours. The rates of pronuclear formation in hovine oocytes electrically stimulated in 0.28 M mannitol with 0.05, 0.10 and 0.15 mM $Ca^2$+(60.3, 82.2 and 75.0%) were significantly higher than without $Ca^2$+(6.3%) at 12 hours after an electric pulse(p<0.005). The activation rates of Korean Native Cattle oocytes stimulated in PBS supplemented with 0.05, 0.10 and 0.15 mM $Ca^2$+(71.0, 75.8 and 75.4%) were significantly higher than without $Ca^2$+(23.5%) after post-stimulation incubation(p<0.005). After incubation of oocytes in SOF with and without $Ca^2$+ following electric stimulation in 0.28 M mannitol with 0.10 mM $Ca^2$+, the rates of pronuclear formation of bovine oocytes in $Ca^2$+-free SOF(85.7%) was significantly higher than in SOF with 1.71 mM $Ca^2$+(62.5%, p<0.05). When oocytes were stimulated in two electrostimulation media supplemented with $Ca^2$+ and incubated in $Ca^2$+-free SOF, there were no significant differences in the rates of pronuclear formation hetween 0.28 M mannitol and PBS. These results indicate that a single electric pulse could induce activation of Korea Native Cattle oocytes in 0.28 M mannitol and PBS supplemented with $Ca^2$+. Furthermore, to improve the activation rates, it was hetter that stimulated oocytes were incubated in $Ca^2$+-free SOF after electric stimulation than in SOF with $Ca^2$+.

• Korean Journal of Veterinary Research
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• v.33 no.1
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• pp.151-169
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• 1993

The present study was carried out to investigate the best condition for nuclear-cytoplasm fusion and in vitro culture of nuclear transplanted embryos and to investigate the production of nuclear transplanted offsprings. The nuclei from 2-, 4- and 8-cell mouse embryos were transferred into enucleated 2-cell embryos, and the reconstituted embryos were submitted to direct current(DC) pulses at output voltage of 1.0, 1.5 and 2.0 kV/cm for 100, 150 and $200{\mu}$ sec to induce cell fusion. 1. The culture of intact or zona cut 2-cell embryos in the medium supplemented with cytochalasin B($5{\mu}g/m{\ell}$) and colcemide($0.1{\mu}g/m{\ell}$)for 30 and 60 minutes did not affect the development to later stage. 2. The in vitro developmental rates of group A(a nucleus from one of the blastomeres was removed) and B(electrofusion of group A) were significantly lower than that of control group(p<0.01). 3. When nuclear transplanted embryos were submitted to electrofusion, the significantly higher fusion rates of 2-cell donor nuclei were achieved at the electric field strength of DC 1.5kV/cm for 100 and $150{\mu}$ sec, DC 2.0 kV/cm for $100{\sim}200{\mu}$ sec than DC 1.0 kV/cm for 100 and $150{\mu}$ sec(p<0.01). The significantly higher fusion rates of 4-cell donor nuclei were achieved at DC 2.0 kV/cm for 100 and $150{\mu}$ sec than DC 1.0kV/cm for $100{\sim}200{\mu}$ sec(p<0.01). These fusion rates in 8-cell donor nuclei were 88.7~99.3%. 4. The developmental potency to blastocyst in 2- and 4-cell donor nuclei was significantly higher in DC 1.0 and 2.0 kV/cm for $100{\sim}200{\mu}$ sec treated group and DC 2.0 kV/cm for 150 and $200{\mu}$ sec treated group (p<0.01). The developmental potency to blastocyst in 8-cell donor nuclei was significantly higher in DC 2.0 kV/cm for $100{\mu}$ sec treated group than in DC 1.0 kV/cm for $100{\mu}$ sec treated group and DC 2.0 kV/cm for 150 and $200{\mu}$ sec treated group(p<001). 5. The developmental potency to blastocyst after nuclear transplantation was significantly higher in 2-cell donor nuclei than in 8-cell donor nuclei(p<0.01). 6. The success rate of nuclear injection into enucleated 2-cell embryos was significantly higher in 2-cell donor nuclei than in 4- or 8-cell donor nuclei(p<0.01). 7. The culture time taken for the nuclear transplanted 2-cell embryos to blastocyst stage was significantly longer in 2-cell donor nuclei than in 8-cell donor nuclei(p<0.01). 8. There was no significant difference in the developmental potency of nuclear transplanted embryos within the concentration of EGF at 0 to 15 ng per $m{\ell}$ of BMOC-3 solution. 9. The production rates of offspring after transfer of nuclear transplanted embryos to recipient mouse were significantly higher in 2-cell donor nuclei than in 8-cell donor nuclei(p<0.01).

• Korean Journal of Materials Research
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• v.8 no.12
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• pp.1152-1157
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• 1998

The PZT films were deposited on the Pt/Ti/$SiO_2$/Si substrates using multi- target DC magnetron reactive sputtering. The perovskite single phase with the composition close to the stoichiometric one, was obtained even at high substrate temperature of $540^{\circ}C$ by 2-step method, which is that PZT film was deposited for a short time at low substrate temperature ($480^{\circ}C$) to promote the nucleation of perovskite phase by reducing the volatility of Pb oxide molecules, followed by the deposition at the elevated temperature to suppress the excess incorporation of Pb component in the PZT film. This two-step method, in combination with the RTA treatment, gives rise to good electrical properties of the deposited PZT films: remanent polarifaion,$18\mu$C/$\textrm{cm}^2$; coercive field, 45kV/cm; leakage current of 10$^{-4}$ A/$\textrm{cm}^2$ at high electric field of -500kV/cm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.688-693
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• 2009

In this paper, a half wave-length microstrip antenna was proposed to be able to continuously tune the resonant frequency in the stated area of UHF ISM band. By loading varactor diodes at both edges of the half wavelength antenna, where the electric field is the strongest, and varying the voltage in order to tune the electrical resonance length continuously, it is possible to automatically recover the resonant frequency and input impedance shifted by surrounding environment. When the microstrip antenna(center resonant frequency: 425 MHB) was tested, by adjusting the each voltages of varactor diodes from DC 0.6 to BC 3.0 volts, the resonant frequency under 20 dB return loss was varied 385 to 465 MHz. The peak gain was -0.2 dBd and return loss -10 dB bandwidth was 3.3 MHz(0.8 %).

• Journal of Korea Multimedia Society
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• v.17 no.2
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• pp.124-131
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• 2014

In this paper, we propose the non-contact gesture recognition algorithm using 4- channel electrometer sensor array. ELF(Extremely Low Frequency) EMI and PLN are minimized because ambient electromagnetic noise around sensors has a significant impact on entire data in indoor environments. In this study, we transform AC-type data into DC-type data by applying a 10Hz LPF as well as a maximum buffer value extracting algorithm considering H/W sampling rate. In addition, we minimize the noise with the Kalman filter and extract 2-dimensional movement information by taking difference value between two cross-diagonal deployed sensors. We implemented the DTW gesture recognition algorithm using extracted data and the time delayed information of peak values. Our experiment results show that average correct classification rate is over 95% on five-gesture scenario.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.156-161
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• 2004

In this research, we used discharge tube without dielectric bead or with dielectric beads(SiO$_2$, $Al_2$O$_3$, or ZrO$_2$), and discharge in water at High-voltage pulse$.$DC power supply for removal of Escherichia coli. At the result of experiments, the removal characteristics of Escherichia coli appeared relation ratio to input voltage. Because, the electric field of discharge tube is increased when input voltage is increased. And, discharge tube used dielectric bead(ZrO$_2$), the removal characteristics of Escherichia coli was better than cases of else. And discharge used DC Power, the removal characteristics of Escherichia coli was better than AC Pulse Power.

• Geomechanics and Engineering
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• v.1 no.4
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• pp.275-289
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• 2009

Electroosmosis (EO) is the movement of water in a porous medium under the influence of a direct current (dc). In past decades, electro-osmosis has been successfully employed in many soil improvement and other geotechnical engineering projects. Metal electrodes, such as steel, copper and aluminum have been used traditionally to conduct current. The shortcoming of these electrodes is that they corrode easily during an EO treatment, which results in reduced effectiveness and environmental concerns. More recently, conductive polymers are developed to replace metal electrodes in EO treatment. Electrical vertical drainages (EVDs) are one of these products under trial. The goal of this study is to assess the performance of EVDs for soil improvement and to further understand the scientific principle of the EO process, including the voltage drop at the soil-EVD interface, electrical current density, polarity reversal, and changes in soil physico-chemical properties generated by electroosmosis. It is found from the study that after 19 days of EO treatment with a constant applied dc electric field intensity of 133 V/m, the soil's moisture content decreased by 28%, the shear strength and pre-consolidation pressure increased more than 400%. It is also found that the current density required triggering the water flow in the soil tested, the Korean Yulchon marine clay, is 0.7 $A/m^2$. The project demonstrates that EVDs can serve as both electrodes and drains for soil improvement in short term. However, the EVDs, as tested, are not suitable for polarity reversal in EO treatment and their service life is limited to only 15 days.

• Korean Journal of Materials Research
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• v.6 no.2
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• pp.221-227
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• 1996

60Hz의 교류전계를 사용하는 종래의 Sawyer-Tower회로를 응용하여 0.1Hz의 직류 개념(quasi-DC)의 전계를 이용한 polarization과 strain의 동시 측정을 실시하였다. 측정의 대상으로는 강유전체로서 압전변형을 보이는 재료 중 가장 대표적인 PZT 계와 완화형 강유전체로서 전왜변형을 보이는 재료 중 가장 대표적인 PZT계와 완화형 강유전체로서 전왜변형을 보이는 재료 중 가장 대표적인 PMN계로 하였다. 0.1Hz한 주기의 전계 인가로 이력곡선을 측정할 수 있어서 시편의 발열을 크게 억제할 수 있었고 정확한 온도에서의 측정이 가능하였다. 또한 양방향 전계뿐 아니라 단방향 전계, 바이어스 전계도 인가할 수 있기 때문에 종래의 Sawyer-Tower 방법에서는 얻을 수 없는 강유전성에 관한 다양한 정보를 얻을 수 있었다. 이 방법은 또한 0.1Hz의 전계 하에서 얻을 수 없는 강유전성에 관한 다양한 정도를 얻을 수 있었다. 이 방법은 또한 0.1Hz의 전계 하에서 이력곡선이 측정되는 한 주기 동안에 시편에 부착된 스트레인 게이지를 통해 전계인가에 따른 strain 변화를 동시에 측정할 수 있기 때문에 strain과 polarization의 상관관계를 정확히 조사할 수 있다는 장점이 있다. PMN계에서 인가되는 전계의 넓은 범위에서 전왜정수 Q값을 연속적으로 구할 수 있었다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.857-860
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• 2002

The material that is both conductive in electricity and transparent to the visible-ray is called transparent conducting thin film. It has many field of application such as solar cell, liquid crystal display, transparent electrical heater, selective optical filter, and a optical electric device. In this study, indium tin oxide (ITO ; Sn-doped $In_2O_3$) thin films were deposited on $SiO_2$/soda-lime glass plates by a dc magnetron sputtering technique. The crystallinity and electrical properties of the films were investigated by X-ray diffraction(XRD), atomic force microscopy (AFM) scanning and 4-point probe. The optical transmittance of ITO films in the range of 300-1000nm were measured with a spectrophotometer. As a result, we obtained polycrystalline structured ITO films with (222), (400), and (440) peak. Transmittance of all the films were higher than 90% in the visible range.