• Korean Journal of Materials Research
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• v.3 no.1
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• pp.3-6
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• 1993

Abstract We report the result of measurement for the ferro-to paramagnetic phase transition temperature shift of a gadolinium film. The phase transition temperature has been determined by measuring the resistance changes of film as function of temperature. At the ferro-to paramagnetic transition temperature, we can observe the inflection point of resistance changes. The phase transition temperature of 6600$\AA$ gadolinium film is found to be shifted by 4 $\pm$ 0.$3^{\circ}C$ below the transition temperature of bulk gadolinium. This is the first measurement for the phase transition temperature shift of ferromagnetic gadolinium film. This and further results might give a milestone in resolving the differences between experiments and finite-size scaling theory.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.3
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• pp.39-44
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• 2005

In this paper, we use the 5-ary frequency shift keying method for robust powerline communication. To transmit the data by the 3-ary carrires among 5-ary carrirers and three carriers are 115kHz, 120kHz and 125kHz. Each time of three carrires is 0.33ms and total transmitting time duration from zero crossing point has 1ms. We use the dummy carriers which are 50kHz and 350kHz for monitoring the powerline channel state, dummy signal duration is received during 1ms. Experimentation result is shown that the implemented PLC transceiver has better than chirp transceiver at the capacitive load testing in spite of low transmission power.

• Journal of Korea Society of Digital Industry and Information Management
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• v.9 no.1
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• pp.165-176
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• 2013

This paper introduces the high density discrete wavelet transform using quincunx sampling, which is a discrete wavelet transformation that combines the high density discrete transformation and non-separable processing method, each of which has its own characteristics and advantages. The high density discrete wavelet transformation is one that expands an N point signal to M transform coefficients with M > N. The high density discrete wavelet transformation is a new set of dyadic wavelet transformation with two generators. The construction provides a higher sampling in both time and frequency. This new transform is approximately shift-invariant and has intermediate scales. In two dimensions, this transform outperforms the standard discrete wavelet transformation in terms of shift-invariant. Although the transformation utilizes more wavelets, sampling rates are high costs and some lack a dominant spatial orientation, which prevents them from being able to isolate those directions. A solution to this problem is a non separable method. The quincunx lattice is a non-separable sampling method in image processing. It treats the different directions more homogeneously than the separable two dimensional schemes. Proposed wavelet transformation can generate sub-images of multiple degrees rotated versions. Therefore, This method services good performance in image processing fields.

• Journal of Korea Society of Digital Industry and Information Management
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• v.8 no.3
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• pp.133-145
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• 2012

This paper describes the high density discrete wavelet transformation which is one that expands an N point signal to M transform coefficients with M > N. The double-density discrete wavelet transform is one of the high density discrete wavelet transformation. This transformation employs one scaling function and two distinct wavelets, which are designed to be offset from one another by one half. And it is nearly shift-invariant. Similarly, triple-density discrete wavelet transformation is a new set of dyadic wavelet transformation with two generators. The construction provides a higher sampling in both time and frequency. Specifically, the spectrum of the first wavelet is concentrated halfway between the spectrum of the second wavelet and the spectrum of its dilated version. In addition, the second wavelet is translated by half-integers rather than whole-integers in the frame construction. This arrangement leads to high density wavelet transformation. But this new transform is approximately shift-invariant and has intermediate scales. In two dimensions, this transform outperforms the standard and double-density discrete wavelet transformation in terms of multiple directions. Resultingly, the proposed wavelet transformation services good performance in image and video processing fields.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.100-103
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• 2005

Homogeneously aligned nematic liquid crystal modes are representatively the -FFS (fringe-field switching) mode using liquid crystal (-LC) with negative dielectric anisotropy, the +FFS mode and the IPS (in-plane switching) mode using +LC with positive dielectric anisotropy. In view of image quality evaluation standard of LCD, we compared characteristics of the brightness, the contrast ratio (CR) and color shift when the modes have respectively optimized phase retardation values $(d{\Delta}n)$. Consequently, in the most sensitively viewing angle of a man's physical vision, both FFS modes have advantage over the IPS mode from the brightness & the CR point of view. We are also confirmed that the +FFS mode out of them shows the smallest color shift according to all viewing directions in grey levels.

• Journal of ILASS-Korea
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• v.28 no.2
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• pp.62-67
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• 2023

Recently, the global automobile industry is aiming for a transition from internal combustion locomotives to zero-emission vehicles. Electric vehicles powered by battery energy can operate at peak performance and improve fuel economy by applying multiple motors or multi-speed transmissions. In order to design a two-speed transmission, it is necessary to evaluate and analyze the application system and performance of electric vehicles. In this study, control performance optimization of a twostage battery electric vehicle equipped with an AMT-based automatic transmission was performed and performance according to control pattern changes was analyzed. In order to improve the operating efficiency of the motor, the shift control that sets the optimal operating point according to the vehicle speed and required torque was derived from the motor efficiency map. The performance of battery energy consumption and transmission loss energy according to the hysteresis interval was analyzed and optimized. The hysteresis interval applied to the optimal shift map acted as a factor in reducing the frequency and loss of shifts. It has been shown that keeping the hysteresis interval at about 4 km/h can reduce energy consumption while reducing the number of shifts.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.769-780
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• 2018

This paper presents an analysis of the power gain under partial shading conditions (PSC) when the partial shade loss is being compensated in photovoltaic(PV) system. To analyze the power gain, our study divides the mismatch loss into partial shade loss and operating point loss. Partial shade loss is defined as the power difference between a normal string and a partially shaded string at the maximum power point (MPP). Operating point loss is defined as the power loss due to the operating point shift while following the MPP of the PV array. Partial shading in a PV system affects the maximum power point tracking (MPPT) control by creating multiple MPPs, which causes mismatch losses. Several MPPT algorithms have been suggested to solve the multiple MPP problems. Among these, mismatch compensation algorithms require additional power to compensate for the mismatch loss; however, these algorithms do not consider the gain or loss between the input power required for compensation and the increased output power obtained after compensation. This paper analyzes the power gain resulting from the partial shade loss compensation under PSC, using the V-P curve of the PV system, and verifies that power gain existence by simulation and experiment.

• Journal of applied mathematics & informatics
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• v.38 no.1_2
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• pp.113-132
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• 2020

In this paper, a class of linear second order singularly perturbed delay differential turning point problems containing a small delay (or negative shift) on the reaction term and when the solution of the problem exhibits twin boundary layers are examined. A hybrid finite difference scheme on an appropriate piecewise-uniform Shishkin mesh is constructed to discretize the problem. We proved that the method is almost second order ε-uniformly convergent in the maximum norm. Numerical experiments are considered to illustrate the theoretical results.

• The Mathematical Education
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• v.50 no.1
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• pp.27-40
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• 2011

The purpose of this paper is to analyze and discuss the viewpoint dealing with the fundamental figures-point, line segment, and angle-of elementary school teachers. In fact, our main subjects in this article are as follows; how do elementary school teachers deal with the fundamental figures?, what is the general notion about the fundamental figures of elementary school teachers? Our such subjects come from the survey results about the 'fundamental figures in J. A. Ko(2009); the elementary school students have a tendency to regard the fundamental figures as not mathematical figures. In this article, we discuss mainly the meta-cognitive shift in the transform of notion, for example, from 'congruent' concept to 'equal' concept, about the fundamental figures.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.146-158
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• 1996

The WKB method has been widely used in evaluating of the propagation characteristics of planar waveguides with graded-index profiles. This method, however, yields large errors when a turning point is near or at the discontinuity in the presence of the index discontinuity or index slope discontinuity. Especially, in the case of a truncated-index profile, this phenomenon appears more clearly in the low-order modes and near the cutoff regions. The MWKB method is introduced to reduce these inherent errors of the conventional WKB method. The MWKB method is based on both the linearization of the index profile from an index discontinuity and the introduction of a virtual turning point. It is noticed that the b-v curves obtained by the MWKB method agree well with those of the finite-difference method, and that the phase shift at a turning point depends on both the index profile and its propagation constant. (author). refs., figs.