• The Korean Journal of Applied Statistics
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• v.29 no.4
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• pp.559-569
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• 2016

A long-run relationship of stock, monetary, realty markets, and business conditions has been suggested to exist due to internal and external shocks. This study investigates whether such a relationship really exists and then performs statistical tests to discern features of the long-run adjustment processes from short-run discrepancies because it is difficult to find studies that examine the market relationship. The comovement relationship of the whole market does not appear to hold for the entire study period; however, it is found to exist for the period before the financial crisis. Estimated error correction models show consistently declining equilibrium errors each period that suggests a recovering process of the long-run equilibrium from short-run secessions.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.751-760
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• 2005

The chloride penetration model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion and sorption model provides the estimation of chloride concentration variation according to cyclic humidity and temperature. The humidity diffusion analysis is carried out, and the chloride ion diffusion and sorption analysis are conducted on the basis of the pre-estimated humidity data in each element. Each element has different variables at different ages and locations in analysis. At early ages, the difference of relative humidity between inner and outer concretes causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference of relative humidity between inner md outer concretes with age, the effect of sorption on the chloride ion penetration decreases with age. The cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and increases the quantity of chloride ion around steel at later ages. Therefore, the in-situ analysis of chloride ion Penetration for harbor concrete structures must be Performed considering the cyclic humidity conditionandthelongtermsorption.

• The Journal of the Acoustical Society of Korea
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• v.30 no.1
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• pp.22-32
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• 2011

The present study examined the effects of the complexity of the 3D models on the results of acoustic simulation which is the predominant tool of the acoustical design of buildings. Also, the effects of the 3D model on the auralized sounds were investigated. In order to carry out the study, four 3D models with different levels of complexity were introduced for a real auditorium which have different numbers of surfaces in the persuit of the guidance of odeon room acoustic software. The set-up of models was also based on the level of transition order of the program. And the acoustic experiments were performed measuring room acoustic parameters including SPL, RT, C80, D50. Acoustic computer simulations were performed using four different models. Then, the results of the computer modeling were compared with the measured acoustical parameters. In addition, sound sources were recorded in the field and auralized sounds were made in convolution with the impulse source made from acoustic modeling. Then, subjective tests were undertaken using auralized sounds. As the results, it was found that the result of the acoustic simulation were closer to the real room acoustic properties when 3D model was more particularly made. For the subjective test, the listening materials were acknowledged as similar with the real sound source when more complex 3D model was used. Then, it could be concluded that the complexity of the 3D model affects the results of the acoustic modeling as well as subjective tests.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.104-111
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• 2018

The sensorless control of high efficiency air compressors using a permanent magnet type synchronous motor as an oil-free air compressor is quite common. However, due to the nature of the air compressor, it is difficult to install a position sensor. In order to control the permanent magnet type synchronous motor at variable speed, the inclusion of a position sensor to grasp the position of the rotor is essential. Therefore, in order to achieve sensorless control, it is essential to use a permanent magnet type synchronous motor in the compressor. The position estimation method based on the back electromotive force, which is widely used as the sensorless control method, has a limitation in that position errors occur due either to the phase delay caused by the use of a stationary coordinate system or to the estimated back electromotive force in the transient state caused by the use of a synchronous coordinate system. Therefore, in this paper, we propose a method of estimating the position and velocity using a rotation angle tracking observer and reducing the speed ripple through a disturbance observer. An experimental apparatus was constructed using Freescale's MPU and the feasibility of the proposed algorithm was examined. It was confirmed that even if a position error occurs at a certain point in time, the position correction value converges to the actual vector position when the position error value is found.

• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.70-73
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• 2000

The error diffusion is good for reproducing continuous image to binary image. However the reproduction of edge characteristics is weak in power spectrum analysis of display error. It is suggested for us an edge-enhanced error-diffusion method that is included pre-processing algorithm for edge characteristic enhancement. Pre-processing algorithm is organized horizontal and vertical directional 2nd order differential values and weighting function of pre-filter. The improved Error diffusion using pre-filter, presents a good results visually which edge characteristics is enhanced. The performance of the proposed algorithm is compared with that of the conventional edge-enhanced error diffusion by measuring the RAPSD of display error, the egde correlation and the local average accordance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.297-306
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• 1992

Algorithms for implementing one chip binary image processor has been studied. In this paper, image quality improvement algorithms, for the data pre-processed with shading and gamma correction after digitizing the analog signal from CCD or CIS, such as : Improved high quality binarization algorithm is suggested. Error diffusion algorithms for high quality half-tone images is analyzed, Fuzzy Theory based mixed mode algorithm is suggested.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.179-181
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• 2005

There is asymmetric in horizontal and vertical side of PDP cell. Every vertical line has BM(Black Mask) to improve luminance contrast. When error diffusion is processed in PDP system, these problems make an error bigger. In 4 inch PDP system, every red, green, blue color of test pattern is presented and each luminance is measured. That is called horizontal(H), diagonal right(R), diagonal left(L) and vertical(V). In red channel, high luminance descending order is V-H-R-L. In green channel, V-H-L-R. In blue channel, V-M-R=L. After average luminance of each direction is calculated. new weighted error diffusion(Weighted ED) is proposed. In digital image signal processing, the error in weighted ED is differ from ED's. The image of weighted ED is more less error compare to conventional ED and close to original image. As the gray level linearity and big size panel is adopted, weighted ED could produce good image.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.461-464
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• 2003

This paper proposes the multi-level vector error diffusion for smear artifact reduction in the boundary regions. Smear artifact mainly results from a large accumulation of quantization error. Accordingly, to reduce these artifacts, the proposed method excludes the large quantization error in the error diffusion process by comparing the magnitude of the error vector with predetermined first threshold. In addition, if the vector norm of the difference between the error adjusted input vector and the primary co]or that has minimum vector norm for the error adjusted input vector is larger than second threshold, the error is excluded. As a result, the proposed method reduce smear artifact in the boundary region and produces visually pleasing halftone pattern.

• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.381-384
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• 2003

Among digital halftoning methods, error diffusion is a procedure for generating high quality bilevel images from continuous-tone images but blurs the edge information in the bilevel images. To solve the problem, we propose the edge enhanced error diffusion using the edge information of the original images. The edge enchanted weights is computed by adding local characteristic weights and input pixels multiplied a constant. Also, we combined the edge enhanced method with the adaptive error diffusion using human spatial and frequency perception characteristic. The performance of the proposed method is compared with conventional method by measuring the edge correlation. The halftoned images applied the proposed method get more fine quality due to the enchanced edge and better quality in halftoned image. And the detailed edge is preserved in the halftoned images by the proposed method.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.1747-1750
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• 2003

This paper proposes a multilevel vector error diffusion for fast and accurate color reproduction. Proposed method considered both hue angle and Euclidean distance during the multilevel vector error diffusion procedure to improve time complexity and output image quality In the error diffusion process, it can be determined whether error is diffused or not by comparing the vector norm and lightness value between original vector and error corrected vector of neighborhood pixels. For adaptive selection of output patch, this paper computes chroma value of error corrected vector and compares the hue angle between error corrected input vector and 64 primary color vectors.