• The KIPS Transactions:PartB
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• v.11B no.2
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• pp.199-206
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• 2004

This paper proposes a hybrid independent component analysis(ICA) of fixed-point(FP) algorithm and robust algorithm. The FP algorithm is applied for improving the analysis speed and performance, and the robust algorithm is applied for preventing performance degradations by means of very small kurtosis and temporal correlations between components. And the adaptive adaptation of temporal correlations has been proposed for solving limits of the conventional robust algorithm dependent on the maximum time delay. The proposed ICA has been applied to the problems for separating the 4-mixed signals of 500 samples and 10-mixed images of $512\times512$pixels, respectively. The experimental results show that the proposed ICA has a characteristics of adaptively adapting the maximum time delay, and has a superior separation performances(speed, rate) to conventional FP-ICA and hybrid ICA of heuristic correlation. Especially, the proposed ICA gives the larger degree of improvement as the problem size increases.

• Journal of the Korean Magnetics Society
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• v.10 no.1
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• pp.1-6
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• 2000

Amorphous Fe$_{79.7}$Si$_{9.3}$B$_{9.7}$Ni$_{1.4}$ ribbon alloys were fabricated by a single roll method. To enhance D. C. bias properties, the magnetic and micro-structural changes have been investigated as the variation of annealing time and condition. The D. C. bias properties were found to be directly related to micro-structural changes. Primary ${\alpha}$-Fe dendrites with 200∼300 nm showed the best D. C. bias properties, which resulted from the magnetic domain wall pinning effect. Due to the differences of cooling rate, the growth shape and distribution of the dendrites is divided into two areas.

• Journal of the Korean Geophysical Society
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• v.2 no.2
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• pp.123-134
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• 1999

Magnetotelluric responses may be affected by strong anisotropy of the high-conductivity layers (HCL) in the upper mantle or lower crust. We have studied two-dimensional anisotropy MT modelling to examine the effect of high anisotropic media. Electrical properties of a homogeneous anisotropic body are defined by a symmetric conductivity tensor and the problem is described by coupled diffusion equation in the frequency domain. In two-dimensional anisotropic environments, diagonal elements of the impedance tensor have higher values than those in isotropic environments. In some cases, TM mode phases reach more than 90°and apparent resistivities decrease for some frequency range because of telluric distortion. GB decomposition may be used to recover regional responses, but can be affected by the regional anisotropic effect. Considering these results, BC87 dataset was interpreted with a modified anisotropic model.

• 전자공학회논문지 IE
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• v.43 no.4
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• pp.21-27
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• 2006

This paper is for the segmentation and volume calculation of the white matter and gray matter from brain MRI. We segment white matter, gray matter and CSF from the Brain image in the normal and abnormal person, and calculate the volume of segmented tissue. In this paper, we present a new method of extracting white matter, gray matter and CSF and calculation its volume from MR images for brain. And we have developed the determining method of threshold that can extract white matter and gray matter from MR image for brain through the analysis of gray values represented by ratio of each component. We proposed the calculation method of volume for white matter and gray matter by using number of extracted pixels in each slice. This algorithm input CSF/Head volume ratio and age of patient and calculates discriminant value through discriminant expression, classifies normal and abnormal using calculated discriminant value. As a result, we could blow that white matter and gray matter volume decrease and CSF volume increase as we grow gold.

• Journal of the Korean Magnetics Society
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• v.26 no.3
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• pp.86-91
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• 2016

The cogging torque of a brushless dc (BLDC) motor results from the interaction between permanent magnets and iron core, and it causes noise and induce vibrations. During a manufacturing process, assembly tolerances lead to the change of the electromagnetic structure of a BLDC motor where permanent magnets are not properly glued to the surface of rotor core. In this paper, the effect of magnet separation from the surface of rotor core on the cogging torque is investigated due to assembly tolerance. The relationship with key design parameters is considered such as separation between magnets and rotor core, the number of magnets having separation, as well as the several types of arrangements among neighboring magnets. Finite element method (FEM) has been used to analyze a BLDC motor, and the allowable assembly tolerance is proposed to prevent generating noise and vibrations. Within proposed assembly tolerance, it is concluded that the cogging torque of a BLDC motor is decreased, and hence noise and vibrations.

• Investigative Magnetic Resonance Imaging
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• v.15 no.1
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• pp.57-66
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• 2011

Purpose : A new inhomogeneity correction method based on two-point Dixon sequence is proposed to obtain water and fat images at 0.35T, low field magnetic resonance imaging (MRI) system. Materials and Methods : Joint phase-magnitude density function (JPMF) is obtained from the in-phase and out-of-phase images by the two-point Dixon method. The range of the water signal is adjusted from the JPMF, and 3D inhomogeneity map is obtained from the phase of corresponding water volume. The 3D inhomogeneity map is used to correct the inhomogeneity field iteratively. Results : The proposed water-fat imaging method was successfully applied to various organs. The proposed 3D inhomogeneity correction algorithm provides good performances in overall multi-slice images. Conclusion : The proposed water-fat separation method using JPMF is robust to field inhomogeneity. Three dimensional inhomogeneity map and the iterative inhomogeneity correction algorithm improve water and fat imaging substantially.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.341-344
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• 2008

Lightweight concrete is known for its advantage of reducing the self-weight of the structures, reducing the areas of sectional members as well as making the construction convenient. Thus the construction cost can be saved when applied to structures such as long-span bridge and high rise building. However, the lightweight concrete requires specific mix design method that is quite different from the typical concrete, since using the typical mix method would give rise the material segregation as well as lower the strength by the reduced weight of the aggregate. In order to avoid such problems, it is recommended to apply the mix design method of self-consolidating concrete for the lightweight concrete. Therefore experimental tests were performed as such mechanical properties(compressive strength, dry density and structural efficiency) of concrete and dry shrinkage according to ACI committee 209.

• The Journal of Information Technology
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• v.2 no.2
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• pp.251-267
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• 1999

This study examines that pricing multiple on and incremental explanatory power of equity book value(earnings) increase(decrease) as financial health decrease. Test using a sample of 75 bankrupt firms and test using a cross-sectional, pooled sample both yield inference consistent with predictions. It is thus hypothesized that the more bankrupt time are, the higher(lower) pricing multiple book value of equity(earnings) obtained. Findings are robust to inclusion of controls for debt/assets ratio, ROA, and ROIC. Overall, the results is the hypothesis.

• Journal of the Korean Magnetics Society
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• v.3 no.4
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• pp.305-309
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• 1993

Thermal stability of Co/Cu artificial superlattice (AS) prepared by RF-magnetron sputtering and the effect of low temperature annealing on the magnetoresistance of the AS have been investigated in this work. Dependence of annealing behavior on the Cu spacer thickness, Fe underlayer thickness, and kind of the underlayer was examined and the relationship between the interfacial reaction and magnetoresistance was studied. It turned out that when Co/Cu AS was annealed at low temperature ($<450^{\circ}C$), the magnetoresistance could increase in the case of AS with thick spacer Cu ($20~25\AA$) layer, whereas it decreased in the case of AS with thin spacer Cu ($7\AA$) layer, which of the former is in contrast with previous reports and the latter in consistent with them. The increase of magnetoresistance is due to increase of interfacial atomic sharpness, which is supported by low angle X-ray diffraction analysis. The thermal stability of Co/Cu AS was better in the case of thick Fe underlayered AS. Interfacial reaction (separation of intermixed Co and Cu) could be observed at lower temperature for (200)-textured samples than for (111)-textured samples, which can be interpreted in terms of interdiffusion kinetics depending on the crystallographic orientation.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 1977.10a
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• pp.197.1-197
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• 1977

식물생장조절질에 대해서는 식물체 및 미생물 유래의 hormone유, phenol성 물질 및 alkaloid성 물질 등 여러가지가 있다. 이들을 생성하는 미생물중에는 주로 병원성의 mold류와 각균류가 대부분이나 본인은 방녹균에서 종자 발아시에 그 생장을 조절하는 물질을 분리선별하여 이에 대한 몇 가지 성질을 조사한 바 단자엽 및 쌍자기식물의 발아 및 뿌리, 줄기의 성장을 억제하였고 열과 pH에 대해 비교적 안정한 물질임을 알았다.(중략)