• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.230-238
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• 2000

We present the magnetisation reversal dynamics of epitaxial Fe thin films grown on GaAs(001) and InAs(001) studied as a function of field sweep rate in the range 0.01-160 kOe/s using magneto-optic Kerr effect (MOKE). For 55 and 250 ${\AA}$ Fe/GaAs(001), we find that the hysteresis loop area A follows the scaling relation A ∝ H$\^$${\alpha}$/ with ${\alpha}$=0.03∼0.05 at low sweep rates and 0.33-0.40 at high sweep rates. For the 150 ${\AA}$ Fe/InAs(001) film, ${\alpha}$ is found to be ∼0.02 at low sweep rates and ∼0.17 at high sweep rates. The differing values of ${\alpha}$ are attributed to a change of the magnetisation reversal process with increasing sweep rate. Domain wall motion dominates the magnetisation reversal at low sweep rates, but becomes less significant with increasing sweep rate. At high sweep rates, the variation of the dynamic coercivity H$\sub$c/ is attributed to domain nucleation dominating the reversal process. The results of magnetic relaxation studies for easy-axis reversal are consistent with the sweeping of one or more walls through the entire probed region (∼100 $\mu\textrm{m}$). Domain images obtained by scanning Kerr microscopy during the easy cubic axis reversal process reveal large area domains separated by zigzag walls.

• Journal of the Korean Magnetics Society
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• v.15 no.5
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• pp.261-264
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• 2005

The elastic constants, C', of $Th_{3}P_4$-type structure compounds, $La_{3}S_4\;and\;Ce_{3}S_4$, have been analyzed on the basis of band Jahn-Teller mechanism. The distinct difference between two compounds lies in the fact that $Ce^{3+}$ ion has a f electron which produces magnetism. It is shown that the band Jahn-Teller effect is sensitively influenced by the energy splitting of f electronic bands by a cubic crystal field in $Ce_{3}S_4$, and f electrons suppress the elastic softening effect. The energy splitting value obtained from the calculation of elastic constants is found to agree well with the experimental value obtained from the magnetic susceptibility measurement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.6
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• pp.1167-1173
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• 2017

As the society increasingly embraces the high - tech digital information age, the field of image processing becomes progressively more branched out and becoming an imperative field. However, image data is deteriorated due to various causes during transmission and salt and pepper noise is typical. Typical methods for removing salt and pepper noise include CWMF, SWMF, and A-TMF. However, existing methods are somewhat insufficient in their ability to remove noise in salt and pepper noise environments. Therefore, in this paper, after it is determined whether noise removal is needed, the following measures were taken. If the center pixel was non-noise, the original pixel was preserved, If it was noise, we proposed a two - dimensional spline interpolation method and a median filter depending on the noise density of the local mask. For the purpose of objective judgment, we compared the results with that of existing methods and used PSNR (peak signal to noise ratio) as a judgment criterion.

• Journal of the Korean Geosynthetics Society
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• v.15 no.1
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• pp.1-10
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• 2016

Recently, offshore wind farms are increasingly expected, because there are huge resource and large site in offshore. Jeju island has optimum condition for constructing a wind energy farm. Unlike the mainland, Jeju island has stratified structure distribution between rock layers sediments due to volcanic activation. In these case, it can be occur engineering problems in whole structures as well as the safety of foundation as the thickness and distribution of sediment under top rock layer can not support sufficiently the structure. In this study, field lateral load test of the pile for analyzing lateral behavior of the offshore wind turbine which is embedded in basalt. After calculating the subgrade resistance and the horizontal deflection from the measured strain to derive p-y curve from the lateral load test results, the subgrade resistance amplifies the error in the process of differentiation and the error of piecewise polynomial curve fitting is the smallest. In order to calculate the horizontal deflection from the measured strain, the six-order polynomial was used.

• Journal of the Korean Society of Costume
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• v.24
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• pp.143-155
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• 1995

Unlike pure art such as painting and sculpture, dressmaking , a field of special plastic art, is characterized by its physical and functional nature. Having an inseparable relation with form, it is a field of art expressiion the human innersense of beauty in correlation with other various fields of art. In this respect, I think it should be necessary for us to study the forms of art from the past in order to study the forms of art from the past in order to study the correlations and mutual influencies between forms of pure art and dressmaking and to understand modern dressmaking from the standpoint of art. In this context, this study is an attempt to analze how the form and characteristics of OP ART , which represents the trends of the 1960's is embodied in modern dresses. The results are as follows : Fist , the expression of OP ART in dresses have visual effects harmonizing with bodily movements and , also, expanded the range and dynamics of expression which resulted from the introduction of visual phenomena in a fresh new sense by not limiting itself to the suggestion of patterns of OP ART. Second, OP ART paintings expressed the mobility and rhythimicity of a body in a limited space in a two-dimensional plane way of expression . When a dress is worn, however, it expands such mobility and rhythmicity in a cubic , three-dimensional way, maximizing the effects of , and boldly expression, OP ART, it can also create a new silhuette and ability of formation by seeking an open expression of OP ART rather than an expression of OP ART it self , due to the infinite possibility and unpredictability by the dynamics of movements and the elements principle of designs. Third , by applying the patterns of OP ART to dresses, we can obtain special visual effects of design, cover up the body's weak points, and create a desired three -dimensional sense by highlighting the beauty of the body's curved lines. Although modern dresses and OP ART are different genres of art, both have something in common in their pusuits. Since there is a infinite possibility in OP ART, there should be continuous attempts to combine dresses and art satisfying the sense of the times, which will lead dressmaking to a higher-dimensional dressmaking plastic art.

• Journal of the Korean Chemical Society
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• v.22 no.2
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• pp.67-77
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• 1978

MO's of a complex are expanded in terms of the set of Shull-Lowdin functions based on a single point, the nucleus of central metal ion, and the result was interpreted from the viewpoint of perturbation theory. We find that even in the case of $[NiF_6]^{4-}$, which has relatively small covalency, excited configurations with high orbital angular momentum are considerably mixed into $e_g$ and $t_{2g}$, orbitals of central metal ion, and that the distortions in these orbitals differ from each other. Therefore it is concluded that the energy difference between $e^*_g$ and $t^*_{2g}$, orbitals evaluated in the MO scheme has little meaning of the unique parameter 10Dq in the crystal field theory, and that such a unique parameter cannot be defined in a rigorous sense in the MO scheme.

• Proceedings of the KIEE Conference
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• 1988.07a
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• pp.799-801
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• 1988

This paper was studied on the effects of Ca-La-Nb substitution and Zr/Ti ratio variation to Pb(Zr, Ti)$O_3$ system on structural, electrical, optical and sound level characteristics in order to develope the piezoelectric and electrooptic ceramic devices. Also the specimens were prepared by the two stage sintering technique. The molecular formular was X($CaO{\cdot}1/4La_{2}O_{3}{\cdot}1/4Nb_{2}O_{5}){\cdot}(1-X)Pb(Zr_{Y}Ti_{1-Y})O_{3}$(x=100X, y=100Y), and the variation of x was $6{\sim}12$, y was 60${\sim}$49 and second stage sintering time was 20${\sim}$40 hours. The experimental results obtained from this study are as follows : 1. The density was decreased, the grain size was increased according to increase of Ca-La-Nb substitution. 2. The crystal structure was rhombohedral in composition 6/60/40, and the crystal structure was tetragonal and cubic according to increase of Ca-La-Nb substitution. 3. The Ca substitution of PZT system enhanced the sintering property. The Pb site vacancy resulting from the substitution of La-Nb increased the dielectrical constant, the piezoelectric charge constant, the dielectric loss and decreased the coercive field. 4. The resistivity of PZT system which has the P type conduction mechanism increased according to substitution of La-Nb because of the substituent acting as donor. 5. The PZT ceramics varied from ferroelectric substance according to increase of Ca-La-Nb substituent. The coercive field and saturation remanent polarization decreased, and at last straight line according to increase of La-Nb substitution. 6. The amount of Ca-La-Nb substitution to improve the light transmittance of speciment was 10 mol%, the Zr/Ti ratio was 49/51, and the second stage sintering time was 40 hours. 7. According to Ca-La-Nb substitution, the specimens was to be transparent. The 7.5/51/49 specimen was suitable for transparent sound vibrator because it had 58% light transmittance (thick 0.2[mm], wave length 700[mm]) and 48% electromechanical coupling factor.

• Current Applied Physics
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• v.18 no.11
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• pp.1248-1254
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• 2018

Magnetization versus temperature and magnetic-field measurements, M(T, $H_a$), have been carried out to study the magnetic and critical properties of polycrystalline $La_{1-x}Ba_xCoO_3$ (x = 0.3 and 0.5) cobaltites. These compounds with the density of ${\sim}6.2g/cm^3$ crystallized in the $R{\bar{3}}c$ rhombohedral and $Pm{\bar{3}}m$ cubic structures, respectively. With an applied field $H_a=200Oe$, M(T) data have revealed that the samples with x = 0.3 and 0.5 exhibit the ferromagnetic-paramagnetic (FM-PM) phase transition at the Curie temperature points $T_C=202$ and 157 K, respectively. At 4.2 K, the saturation magnetization ($M_{sat}$) decreases from 35.9 emu/g for x = 0.3-26.1 emu/g for x = 0.5. Particularly, the critical-behavior analyses in the vicinity of $T_C$ reveal all samples undergoing a second-order phase transition, with critical exponent values (${\beta}=0.328$ and ${\gamma}=1.251$ for x = 0.3, and ${\beta}=0.331$ and ${\gamma}=1.246$ for x = 0.5) close to those expected for the 3D Ising model. This proves short-range magnetic order existing in $La_{1-x}Ba_xCoO_3$. We believe that magnetic inhomogeneities due to the mixture of hole-rich FM regions (confined in the trivalent-cobalt hole-poor anti-FM matrix) and uniaxial anisotropy prevent long-range order in $La_{1-x}Ba_xCoO_3$.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.126-135
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• 2015

Increase of delivery effect of pollutant loads and surface runoff due to urbanization of catchment area results in serious environmental problems in receiving urban streams. This study aims to develop integrated stormwater management system to assist efficient urban stream flow and water quality control using information from the Storm Water Management Model (SWMM), real time water level and quality monitoring system and remote or automatic treatment facility control system. Based on field observations in the study site, most of the pollutant loads are flushed within 4 hours of the rainfall event. SWMM simulation results indicates that the treatment system can store up to 6 mm of cumulative rainfall in the study catchment area, and this means any type of normal rainfall situation can be treated using the system. Relationship between rainfall amount and fill time were developed for various rainfall duration for operation of stormwater treatment system in this study. This study can further provide inputs of river water quality model and thus can effectively assist integrated water resources management in urban catchment and streams.

• Journal of the Korean Magnetics Society
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• v.10 no.2
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• pp.74-80
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• 2000

CoCr$_{x}$ Fe$_{2-x}$O$_4$(0.0$\leq$x$\leq$1.0) ferrites have been fabricated by sol-gel method. The crystallographic and magnetic properties of the samples were investigated by means of x-ray diffraction, scanning electron microscophy, Mossbauer spectroscopy and vibrating sample magnetometry. The structure of all the samples is cubic spinel type and the lattice constant decrease with increasing Cr content. The substituted Cr ions were located only in the B-site. The particle size also decreases with increasing Cr content. The Mossbauer spectra consist of two sextets due to Fe$^{3+}$ions at A- and B sites for 0.0$\leq$x$\leq$0.6, while, a paramagnetic doublet appears for 0.8$\leq$x$\leq$1.0. The magnetic hyperfine field decreases with increasing Cr content. The relaxation spectra was shown at 0.8$\leq$x$\leq$1.0 in CoCr$_{x}$ Fe$_{2-x}$O$_4$. The coercivity decreases drastically, while, the saturation magnetization decreases linearly with increasing x.ing x.