• 한국전기전자재료학회논문지
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• 제18권4호
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• pp.338-343
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• 2005

Pb(Zr,Ti)O₃[PZT] thin films were prepared on a highly (100) oriented LaNiO₃[LNO] and a randomly oriented LNO by sol-gel process. The PZT thin films on a highly (100) oriented LNO show a high (100) crystal orientation (F=100 ％), those on a randomly oriented LNO show a random crystal orientation (F=60 ％). All the PZT layer have a flat and dense microstructure with large columnar grains and their grain size are 25 nm. In the ferroelectric curves at electric field of 40 kV/cm, a highly (100) oriented PZT/LNO samples show coercive field, E/sub c/=10 kV/cm and remanent polarization, P/sub r/=14.5 μC/㎠, while a randomly oriented PZT/LNO sample show E/sub c/=10 kV/cm and P/sub r/=5.4 μC/㎠.

• 전자공학회논문지A
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• 제28A권11호
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• pp.866-873
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• 1991

In this paper the electric and magnetic field distributions in a TEM cell used for EMC testing are analyzed numerically. The fields are distorted with the increase of frequency. These distortions are due to higher order modes and resonances and cause the bandwidthe limitations in the uae of TEM cels. The upper frequency is lower modes however, are reflected at some points through the tapered ends of the cell. Higher order modes however, are reflected at some points within the tapered region where it becomes too small to support the modes, The first two TE mode(TE$_{01}$ and TE$_{10}$) cutoff frequencies and the first six TE$_mnp$ resonant ferquencies are identified in a TEM cell (1x0 6x2m,w=0.72m) from field patterns and the results are consistent with others' data. The circumferential wall currents to support resonances are shown. For the large cell it is desired to extend the usable frequency range above the cutoff frequency of the first higher order mode. This study proposes an attempt to expand the frequency bandwidth by a resonance suppression.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제51권7호
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• pp.370-378
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• 2002

As resent trends in structural construction have been to build taller and larger structures than any time in the past, they have had high flexibility and low damping that can cause large vibration response under severe environmental loading such as earthquakes, winds, and mechanical excitations. The damper with mass and spring is one approach to safeguarding the structure against excessive vibrations. In this paper, the lumped electrical circuit approach of mass/spring system is used to model the mechanical aspects according to the frequency. Therefore, the mass/spring system can be dealt with here and linked with the equivalent circuit of electric linear oscillatory actuator(LOA). Analysis models are two types of vibration control system, active mass damper(AMD) and hybrid mass damper(HMD). AMD consists of the moving coil LOA with mass only The LOA of HMD with mass and spring is composed of the fixed coil and the movable permanent magnet(PM) field part. The PM field part composed magnet modules and iron coke, is the damper marts itself. We Present the motional resistance and reactance of mass/spring system and the system impedance of AMD and HMD according to the frequency.

• 한국공작기계학회논문집
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• 제16권1호
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• pp.75-79
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• 2007

The cathode design is one of the most important parts in order to enhance the performance of fuel cells. A 3-D model of the porous oxygen reducing cathode with perforated current collectors is analysed for the enhanced design in fuel cells. Simulation is performed using equations of electric potential balance, momentum balance, and mass balance. The gas concentrations are quite large and are significantly affected by the reactions that take place. The weight fraction of oxygen, velocity field for the gas phase, and local overvoltage are illustrated in the porous reactive cathode layer. The current density is also analysed and the result shows the distribution and variation are stated in a wide range. It is found that the rate of reaction and the current production is higher beneath the orifice, and decreases as the distance to the gas inlet increases. The significance of the results is discussed in the viewpoint of the mass transportation phenomena, which is inferred that the mass transport of reactants dictates the efficiency of the electrode in this design and at these conditions.

• 한국재료학회지
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• 제17권3호
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• pp.167-172
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• 2007

The separation of the small colloidal particles from the mixture of two different sized particles using AC dielectrophoresis phenomenon was studied. The spherical mono-dispersed polystyrene particles dispersed in pure water were put into a perfusion chamber on a substrate, and AC electric fold was applied to the glass substrate with Au electrodes in 4 mm distance. The AC frequency was fixed at 1 kHz and the intensity of the field was varied from 25 V/cm to 160 V/cm. After applying the AC field, the degree of the chain formation that resulted from the particle movements by dielectrophoresis was observed by optical microscope. The mixture of the $1\;{\mu}m\;and\;5\;{\mu}m$ sized polystyrene particles at 0.5 vol% concentrations for each size was set in the dielectrophoresis conditions of 1 kHz and 100 V/cm. At this condition large $5\;{\mu}m$ sized polystyrene particles formed chains, on the contrary the $1\;{\mu}m$ sized polystyrene particles formed no chains. After water flowing for 20 min, it was found that small particles that were floating in the chamber had been removed by the water flowing.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 일렉트렛트 및 응용기술
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• pp.132-137
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• 2002

The mold transformers have been widely used in underground substations in large building and have some advantages in comparison to oil-transformer, that is low fire risk, excellent environmental compatibility, compact size and high reliability. In addition, the application of mold transformer for outdoor is possible due to development of epoxy resin. The mold transformer generally has cooling duct between low voltage coil and high voltage coil. A mold transformer made by one body molding method has been developed for small size and low loss. The life of transformer is significantly dependent on the thermal behavior in windings. To analyse winding temperature rise, many transformer designer have calculated temperature distribution and hot spot point by finite element method(FEM). Recently, numerical analyses of transformer are studied for optimum design, that is electric field analysis, magnetic field, potential vibration, thermal distribution and thermal stress. In this paper, the temperature distribution of 50 kVA pole mold transformer for power distribution are investigated by FEM program and the temperature rise test of designed mold transformer carried out and test result is analyzed compare to simulation data. In this result, the designed mold transformer is satisfied to limit value of temperature and the other property is good such as voltage ratio, winding resistance, no-load loss, load loss, impedance voltage and percent regulation.

• Journal of Radiation Protection and Research
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• 제41권4호
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• pp.373-377
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• 2016

Background: Experiments with small electrochemical apparatus were previously carried out for detecting low-energy neutrinos under irradiation of reactor neutrinos and under natural neutrino environment. The experimental result indicated that the output current of reactor-neutrino irradiated detector was appreciably larger than that of natural environmental one. Usual interaction cross-sections of neutrinos are quite small, so that they do not explain the experimental result at all. Materials and Methods: To understand the experimental data, we propose that some biological products may generate AV-type scalar field B0, leading to a large interaction cross-section. The output current generation is ascribed to an electrochemical process that may be assisted by weak interaction phenomena. Dissolved oxygen concentrations in the detector solution were measured in this study, for the purpose of understanding the mechanism of the detector output current generation. Results and Discussion: It was found that the time evolution of experimental output current was mostly reproduced in simulation calculation on the basis of the measured dissolved oxygen concentration. Conclusion: We mostly explained the variation of experimental data by using the electrochemical half-cell analysis model based on the DO concentration that is consistent to the experiment.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권5호
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• pp.291-296
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• 2000

Recently large size color TV and computer monitor are very popular and a lot techniques are being developed to get a high quality picture on the screen through reducing the convergence error among the red, green and blue beams and achieving a high focusing. One of the techniques is considering the mutual effects of the components of the Brown tube. The magnetic deflection yoke, especially, stands immediately next to the electron gun and generates the leakage magnetic fields at the electron gun which affects the trajectories of the electron beams inside the gun. Hence a shield cup made of thin conducting plate is located at the end of electron gun in order to shield the leakage flux from the deflection yoke. Since the red, green and blue beams are placed unsymmetrically the shielding effects of the shield cup on the beams are not same and eddy current controller, made of thin conducting plate, is auxiliary placed inside the shield cup. In this paper a transient magnetic field analysis algorithm is developed using boundary element method, and applied to the analysis of the shielding effects of the eddy current controller of shield cup in an electron gun.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.358-360
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• 2007

For large scaled solar cells and photosensors CdS thin films of $2{\mu}m$ thickness have deposited on ITO glass substrate by chemical bath deposition methode in $300^{\circ}C$ electric furnace. The surface roughness and resistance of cadmium sulphide(CdS) thin films with different microstructures and morphologies was investigated by using a x-ray diffraction (XRD), a scanning electron microscope (SEM), an atomic force microscope (AFM), and a near-field scanning microwave microscope (NFMM). As the different substrate heat temperatures, the microwave reflection coefficient $S_{11}$ and intensity of the (002) diffraction peak was changed, and the surface morphology also has shown differently.

• 해양환경안전학회지
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• 제27권5호
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• pp.675-682
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• 2021

육상 및 해상에서의 화재 사고는 심각한 인명피해를 발생시키며 특히 해양 플랜트 및 선박의 특성 상 밀폐공간으로 인한 질식사고 사망률이 육상보다 현저히 높다. 이러한 질식사고를 예방하기 위하여 화재에서 발생하는 유독가스를 외부로 배출할 수 있는 환기용 팬의 설치가 필수적이나, 해양화재의 규모를 고려하였을 때 대형 환기용 팬의 설치는 해양 구조물 특성 상 용이하지 않다. 따라서 본 연구에서는 DC 전기장을 인가하여 화재 유독가스를 제어하는 새로운 개념의 소방기술을 개발하고자 한다. 화재 발생 시 대부분의 화염은 화학 이온화로 인해 양전하와 음전하를 다수 함유하고 있고, 이때 전기장을 인가하게 되면 로렌츠 힘에 의해 "이온풍"이 발생하게 된다. 이러한 이온풍을 활용하여 일반건축물과 선박의 단열재로 많이 사용되는 종이와 스티로폼을 연소하여 발생되는 화재연기를 인위적으로 제어하는 실험적 연구를 수행하였다. 실험 결과, ± 5 kV 이상의 직류전압을 인가하였을 때 화재연기를 인위적으로 제어할 수 있었고, 양전압보다 음전압을 인가하였을 때 상대적으로 효과적인 제어가 가능하였다.