• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.641-646
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• 2004

We report the changes of the microwave reflection coefficients S$_{11}$ of copper(II)-phthalocyanine (CuPc) thin films by using a near-field microwave microscope(NSMM) in order to understand the phase transition of CuPc. For a NSMM system, a high-quality microstrip resonator coupled with a dielectric resonator was used. CuPc thin films were prepared on the pre-heated glass substrates using a thermal evaporation method. The reflection coefficients S$_{11}$ of CuPc thin films were changed by the dependence on the substrate pre-heating temperatures. By comparing reflection coefficient S$_{11}$ and crystal structures, we found the phase transition of CuPc thin films from $\alpha$-phase to $\beta$-phase at the substrate heating temperature 200 $^{\circ}C$./TEX>.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.174-174
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• 2003

Highly (111)-oriented PZT [Pb(Zrl-xTix)O3] thin films in the Zr-rich rhombohedral phase-field were successfully fabricated on Pt(111)/Ti/SiO2/Si substrates by combining PLD method with sol-gel process. These highly (111)-oriented films can be used as model systems for polarized Raman scattering study of PZT in the rhombohedral-Phase field because the (111)-direction is the principal off-center axis of the rhombohedral ferroelectricity. For this purpose, we have fabricated PZT films employing two distinctive compositions : one with Zr/Ti = 90/10 (abbreviated as PZT90/10) and the other with Zr/Ti= 60/40 (PZT60/40). The PZT90/10 film belongs to the octahedrally distorted FR(LT) phase with a cell-doubled structure, whereas the PZT60/40 is in the high-temperature FR(HT) phase-field at room temperature. To clearly separate E(TO) phonon modes from Al(TO) modes of the (111)-oriented rhombohedral film, we have suitably devised Z(X,Y)Z and Z(X,X)Z backscattering geometries for E(TO) and Al (TO), respectively. The polarized scattering experiment demonstrated that both types of (111)-oriented rhombohedral films closely followed the Raman selection rule.

• Korean Journal of Optics and Photonics
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• v.8 no.2
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• pp.161-164
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• 1997

A new hybrid, heterodyne, fiber-optic electric field sensor scheme is presented. In this scheme, a dual polarization, dual frequency, stabilized He-Ne laser is used for the light source of the interferometer, Probe beam is delivered to the sensor head using polarization maintaining fiber. In the sensor head, $LiTaO_3$ electro-optic crystal is used for sensing element. Phase retardation is induced on the dual frquency, dual polarization probe beam due to applied electric field across the crystal. Induced phase retardation is demodulated by in-phase and quadrature demodulation technique. In this way, we can obtain optimum sensitivity for electric field measurement regardless a quasi-static phase difference between two polarization components.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1996.06a
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• pp.139-156
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• 1996

The phase field model is becoming the model of choice for the theoretical study of the morphologies of crystals growth from the melt. This model provides an alternative approach to the solution of the classical (sharp interface) model of solidification by introducing a new variable, the phase field, Ø, to identify the phase. The variable Ø takes on constant values in the bulk phases and makes a continuous transition between these values over a thin transition layer that plays the role of the classically sharp interface. This results in Ø being governed by a new partial differential equation(in addition to the PDE's that govern the classical fields, such as temperature and composition) that guarantees (in the asymptotic limit of a suitably thin transition layer) that the appropriate boundary conditions at the crystal-melt interface are satisfied. Thus, one can proceed to solve coupled PDE's without the necessity of explicitly tracking the interface (free boundary) that would be necessary to solve the classical (sharp interface) model. Recent advances in supercomputing and algorithms now enable generation of interesting and valuable results that display most of the fundamental solidification phenomena and processes that are observed experimentally. These include morphological instability, solute trapping, cellular growth, dendritic growth (with anisotropic sidebranching, tip splitting, and coupling to periodic forcing), coarsening, recalescence, eutectic growth, faceting, and texture development. This talk will focus on the fundamental basis of the phase field model in terms of irreversible thermodynamics as well as it computational limitations and prognosis for future improvement. This work is supported by the National Science Foundation under grant DMR 9211276

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.6
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• pp.57-67
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• 2011

Purpose of this study is to find the mitigation method of magnetic field by finite length multi-conductors such as indoor distribution lines and to be applicable to design of the distribution lines. For this purpose, exact formula about the components $B_x$, $B_y$, $B_z$ of magnetic field need in case of straight line-conductor with finite length forward any direction. In this study simple formula of the components were deduced and by using these formula magnetic fields for various models of line-configurations were calculated. And also a calculation method of induced currents in conductive shield was presented and using this method, programing of calculation is relatively easy and calculation time is short. The magnetic field after cancellation by these induced currents was calculated. All of calculations were performed by Matlab 7.0 programs. Through the calculation results it could be obtained followings for the mitigation of magnetic fields. The separation between conductors ought to be smaller than smaller as possible. In case of 3-phase, delta configuration is more effective than flat configuration. In case of 3-phase, unbalanced currents ought to be reduced as possible.. In case of more than two circuits of 3-phase, adequate locations of each phase-conductor such as rotating configuration of 3-phase conductors are more effective. The magnetic shielding effect of the conductive shielding sheet is very high.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.250-252
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• 1997

Phase difference of external magnetic field and self field is known to do an important role in the generation of the AC loss. This paper analize the AC loss of AC superconducting wire in combined action of an AC transport current and AC magnetic field for various phase differences.

• Geomechanics and Engineering
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• v.31 no.2
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• pp.159-166
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• 2022

The model of two-dimensional plane waves is analyzed in a micropolar-thermoelastic solid with microtemperatures in the context of the three-phase-lag model, dual-phase-lag model, and the Green-Naghdi theory of type III. Harmonic wave analysis is used to hold the solution to the problem. Numerical results of the physical fields are visualized to show the effects of the gravity field, magnetic field, and viscosity. The expression for the field variables is obtained generally and represented graphically for a particular medium.

• Journal of the Korean Society of Safety
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• v.21 no.2 s.74
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• pp.22-28
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• 2006

This paper presents assessment of possibility on the human risk for the electromagnetic field of unbalanced two coupled three-phase transmission line using fuzzy theory. Three phase load flow program was developed which employed a Newton-Raphson method as a tool to analyze system unbalanced. This research presents a method of handling two coupled three phase transmission system unbalance analysis and unbalanced power demand as a function of voltages. As the results of case study, in case of 345[kV] T/L, the electric field intensity was 10.9540[kV/m], magnetic field intensity was 0.2567[G] in severest case. The results showed that the membership of a proposition fuzzy '10.9540 [kV/m] is hazardous' is 0.6349. As the analytic results using the fuzzy qualifier term, the membership in case of very false is 0.1379 and fairly false is 0.6124, respectively. In assessment of fuzzy measure possibility for the electromagnetic field, this paper used probability of fuzzy arid measure of fuzziness technique.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.4
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• pp.39-45
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• 1997

Shadow moire topography has been used as a noncontact method for measuring the 3-D shapes of objects. The moire fringes are results from the superposition of a master grating and its shadow projected on the surface of an object. But in case of the classical shadow moire method, in general, the resolution is a few tenths of millimeter. It is difficult to use a phase -shifting method in shadow moire because it is impossible to obtain uniform phase shifts on the whole field. But in this study , We introduce a phase-shifting method to improve the resolution of the classical shadow moire method. This method is based on the fact that if the depth of object is much less than the distance between the observer and the master grating, the phase shifts are almost uniform on the whole field area. Finally, we applied this new phase-shifting method to the measurement of the 3-D shape of a coin.

• Journal of Soil and Groundwater Environment
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• v.18 no.3
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• pp.93-108
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• 2013

This study is aimed to prepare the effective detail survey methods(Phase II) of abandoned metal mines through the contamination assessment for mine types and facilities in the abandoned metal mine areas. The study sites of 12 abandoned mines are located in Gyeonggi-do and Gangwon-do and those were chosen among 310 sites that the Phase II survey was conducted from 2007 to 2009 after considering the results of Phase I for abandoned mines scattered all over the country. 12 study sites were classified into four types; Type I sites only have pit mouth. Type II sites have pit mouth and mine-waste field. Type III sites have pit mouth and tailing sorting field. Type IV sites have pit mouth, tailing sorting field and concentrator(s). In forest land, paddy soil and farm land of Type I, As and Cd were showed average concentration, and Cu and Pb were high on the pit mouth area in one mines where the pit mouth was developed within 500 m. In the mines of Type II, Cu and Pb were showed average concentration too, but As and Cd were slightly high in pit mouth and mine-waste field. The mines of Type III which had grinding particle process through physical separation milling or hitting showed similar tendency with Type II. However, mines of Type IV pit mouth, mine-waste field and showed various results depending on defining the contamination sources. For example, if contamination source was pit mouth, the mixed results of Type I, II, II were showed. In tailing sorting field which was regarded as the most important source and having high mobility, however, if there were no facilities or it was difficult to access directly, field sampling was missed occasionally during phase I and phase II survey. For that reason, the assessment for tailing sorting field is missed and it leads to completely different results. In the areas of Type I mines, the concentration of heavy metals exceeded precautionary standards of soil contamination or not within 1,000 meters of pit mouth. Nickel(Ni) was the largest factor of the heavy metal contamination in this type. The heavy metals except Arsenic(As) were shown high levels of concentration in Type II areas, where pit mouth and mine-waste field were operated for making powder in upriver region; therefore, to the areas in the vicinity of midstream and downstream, the high content of heavy metals were shown. The tendency of high level of heavy metals and toxic materials contained in flotation agent used during sorting process were found in soil around sorting and tailing field. In the abandoned-pit-mouth area, drygrinding area and tailing sorting field area, the content of Cupper(Cu) and Zinc(Zn) were higher than other areas. Also, the contaminated area were larger than mine reclamation area(2,000 m) and the location of tailing sorting field was one of the important factors to estimate contaminated area.