• Journal of the Korean Ceramic Society
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• v.38 no.6
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• pp.499-505
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• 2001

The behaviour of ionic compound crystals under combined chemical and externally applied electrical potential gradients is discussed. Firstly, a systematic overview is given. Then a formal analysis follows. The transport equations of the ions and the electric defects predict that even with reversible electrodes demixing, and in particular decomposition of the compound will occur if the applied d.c. current density is sufficiently high. These predictions are illustrated by appropriate experiments. With the help of the solid solution (Me, Fe)O, where Fe-ions are the dilute species, we investigate experimentally the behaviour of a ternary ionic crystal under a d.c. electric current load. All the compounds were placed in a galvanic cell, and the internal reactions which then could be observed were driven by the electric field in this cell. In addition, we discuss the influence of the electric field on the classical solid state reaction AX+BX=ABX$_2$, if again the reaction couple is placed in a galvanic cell.

• 전기의세계
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• v.16 no.1
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• pp.7-13
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• 1967

There are many kinds of motors operating by rated voltage which is constant. In this paper, the characteristics of separately excited direct current motor is analyzed when its terminal voltage is varied as its load current. As for this source, direct current generator of a series field is used, and it is driven at constant speed by a primemover. The induced voltage of the generator is propotional to its load current but it saturates as its load current is large. The charateristics of motor is studied by analog computer because of the nonlinearity of generator. The results are as follows: (1) The load current and the rotor speed of motor increase as the load of motor increases. But the speed of rotor decreases for the influence of the saturation of the iron of generator field when its load current is large. (2) Decreasing the inertia of motor and increasing the inductance of the armature circuit improve the stability of motor and the region of stable state. (3) By changing the field current of the motor, the speed and the direction of rotor can be controlled in wide range.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.751-753
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• 2001

The characteristic of magnetostrictive is to change shape in a magnetic field, TERFENOL-D is said to produce magnetostriction. A magneto strictive actuator need to the magnetic circuit. The most important design consideration is the magnetic circuit. The magnetic circuit consists of the solenoid coil, permanets for bias and shaping of the other parts through which the magnetic field passes. A good magnetic circuit ensures the proper magnetic field in th TERFENOL-D and very uniform magnetic field in all phases of the actuator operating cycle. This paper presents magnetic circuit design and analysis uesing FEM.

• Korean Journal of Mathematics
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• v.25 no.2
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• pp.215-227
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• 2017

Let D be an integral domain with quotient field K, X be an indeterminate over D, K[X] be the polynomial ring over K, and $R=\{f{\in}K[X]{\mid}f(0){\in}D\}$; so R is a subring of K[X] containing D[X]. For $f=a_0+a_1X+{\cdots}+a_nX^n{\in}R$, let C(f) be the ideal of R generated by $a_0$, $a_1X$, ${\ldots}$, $a_nX^n$ and $N(H)=\{g{\in}R{\mid}C(g)_{\upsilon}=R\}$. In this paper, we study two rings $R_{N(H)}$ and $Kr(R,{\upsilon})=\{{\frac{f}{g}}{\mid}f,g{\in}R,\;g{\neq}0,{\text{ and }}C(f){\subseteq}C(g)_{\upsilon}\}$. We then use these two rings to give some examples which show that the results of [4] are the best generalizations of Nagata rings and Kronecker function rings to graded integral domains.

• Journal of the Microelectronics and Packaging Society
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• v.30 no.2
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• pp.43-51
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• 2023

In this paper, we introduce the development trends of power devices which is the key component for power conversion system in electric vehicles, and discuss the characteristics of the next-generation wide-bandgap (WBG) power devices. We provide an overview of the characteristics of the present mainstream Si insulated gate bipolar transistor (IGBT) devices and technology roadmap of Si IGBT by different manufacturers. Next, recent progress and advantages of SiC metal-oxide-semiconductor field-effect transistor (MOSFET) which are the most important unipolar devices, is described compared with conventional Si IGBT. Furthermore, due to the limitations of the current GaN power device technology, the issues encountered in applying the power conversion module for electric vehicles were described.

• Asian Journal of Turfgrass Science
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• v.15 no.3
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• pp.127-136
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• 2001

A field trial was initiated to examine the range of inter- and intraspecific variations in morphological and phenological traits with five different accessions of smooth and large crabgrass. In addition, a controlled environment study was conducted to determine the phenotypic plasticity among the accessions of both species in response to 4 daily tempera-ture differentials. In the field experiment, significant inter- and intraspecific variations of smooth and large crabgrass were observed in morphological traits such as leaf length and width. However, most phenological traits were not substantially different between the species and among the accessions of each species. The first seedling emerged at the same time, requiring 9~ 10 days, regardless of the accessions and species. In a controlled environment study, all accessions of each species responded similarly to the 4 temperature differentials in seedling emergence, indicating seedling emergence was not a plastic trait. These results suggest that predicting crabgrass seedling emergence could be independent of geographical regions in the US.

• Proceedings of the KIEE Conference
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• 2003.07a
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• pp.212-214
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• 2003

A passive loop is considered to be a cheap and easy way to be realized among the magnetic field mitigation methods. So this paper evaluates and quantizes systematically the effectiveness of a passive loop on mitigating magnetic field(M-field) and examines the feasibility and problems in adoption. To do so, first, we explain the principles of M-field mitigation through a passive loop and derive formulas for 2-D M-field analysis. Next this paper simulates the M-field mitigation patterns for a flat type 1-circuit transmission line installed a passive loop.

• Proceedings of the Korean Society of Crop Science Conference
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• 1992.05a
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• pp.88-89
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• 1992

• Mycobiology
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• v.28 no.4
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• pp.185-189
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• 2000

The antifungal activity of methanolic extracts of Centella asiatica and Andrographis paniculata leaves was observed against fourteen fungi, viz., Alternaria alternata, A. brassicae, A. brassicicola, A. solani, A. tenuissima, Cercospora blumae, Curvularia lunata, C. penniseti, and Drechslera monoceras, D. oryzae, D. turitica, Fusarium albizziae and F. udum. Different concentrations of the methanolic extract (1000, 2000, 3000, 5000, 7000, 10000ppm) were used. The effect of mixed leaf extract (1500 ppm of C. asiatica + 1500 ppm of A. paniculata) and its 1:2 ad 1:4 dilutions were also studied. The individual extracts of both the plants showed significant inhibitory effect on spore germination of all the fungi tested. F. udum, F. albizzae, D. oryzae, D. turtica, and D. monoceras were particularly sensitive to these extracts. In general, the extract of C. asiatica showed a higher inhibitory effect in all concentrations against all the fungi as compared to A. paniculata, except for A. brassicae A. solani, D. oryzae, D. penniseti and Curvularia sp. The inhibitory effect of extracts increased when they were used in combination with or without dilutions against A. brassicicola, A. solani A. brassicae, A. alternata, A. tenussima, C. blumae, C. lunata, C. penniseti and Curvularia species. Higher efficacy of active ingredient of these extracts under field condition is envisaged against plant pathogens.

• Computers and Concrete
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• v.2 no.6
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• pp.455-479
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• 2005

This paper describes a 2D nonlinear finite element analysis (NLFEA) platform that combines heat flow analysis with realistic analysis of cracked reinforced concrete structures. The behavior models included in the structural analysis are mainly based on the Modified Compression Field Theory and the Distributed Stress Field Model. The heat flow analysis takes into account time-varying thermal loads and temperature-dependent material properties. The capability of 2D nonlinear transient thermal analysis is then implemented into a nonlinear finite element analysis program VecTor2(C) for 2D reinforced concrete membranes. Analyses of four numerical examples are performed using VecTor2, and results obtained indicate that the suggested nonlinear finite element analysis procedure is capable of modeling the complete response of a concrete structure to thermal and mechanical loads.