• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12A
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• pp.1340-1348
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• 2004

In this paper, we propose a PAPR-minimized sequence mapping scheme that achieves the minimum Peak-to-Average Power Ratio (PAPR) and the minimum amount of computations for the OFDM system. To reduce the PAPR, the mapping table is created with information about block index and symbol patterns of the lower signal power. When the input data sequence comes, it performed division by the block length to find the quotient and remainder. The symbol pattern of the lower signal power can be found in terms of the block index as the quotient in the mapping table and transmitted with remainder as the side information to distinguish and recover the original data sequence in the receiver. The two methods with the proposed mapping scheme are proposed in this paper. One is with mapping table to recover the O%M signal in both transmitter and receiver. The other is with mapping table only in transmitter to reduce the load and the complexity in the mobile system. We show that this algorithm provides the PAPR reduction, the simple processing and less computational complexity to be implemented for the multi-carrier system.

• Explosives and Blasting
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• v.26 no.2
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• pp.29-37
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• 2008

In general, the size of tunnel cross section in construction site is $50{\sim}200m^2$. But, electric cable tunnel, telecommunication cable tunnel, mine tunnel. Waterproof tunnel have small cross section less than $20m^2$. There are so many problem at small sectional tunnel: restriction of equipment, dead pressure by precompression, loss of efficiency, increase of work time. Especially, explosives remainder by precompression of previous detonation is serious problem. To find its measures of dead pressure (explosives remainder), the following series of progress have been conducted: (1) survey of previous study (2) investigate causes of dead pressure (3) set up of its measures (4) application and appraisal at tunnel site. The measures, change of cut pattern, hole space over 40cm, adjustment of delay time, are proved by experimental results.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.2 no.2
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• pp.57-65
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• 1998

An estimation of remainder for Simpson's quadrature formula for differentiable mappings whose derivatives belong to $L_p$-spaces and applications in theory of special means (logarithmic mean, identric mean etc...) are given.

• Communications of the Korean Mathematical Society
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• v.19 no.1
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• pp.75-92
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• 2004

A generalised integration by parts formula for sequences of absolutely continuous functions that satisfy the ${\omega}-Appell$ condition and different estimates for the remainder are provided. Applications for particular instances of such sequences are pointed out as well.

• Journal of the Chungcheong Mathematical Society
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• v.18 no.1
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• pp.81-86
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• 2005

In this paper, we consider locally compact Hausdorff spaces having the closed unit interval of the real line as the remainder for an ESH-compactification and obtain that in the class of compact maps the extensions of homotopic maps on the respective ESH-compactifications remain homotopic under certain conditions.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.6 no.2
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• pp.43-52
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• 2002

By the use of Taylor's expansion formula with the integral remainder, an accurate approximation for the fiber refractive index profile is given.

• Proceedings of the IEEK Conference
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• 2000.11d
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• pp.155-158
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• 2000

In this paper, the quantization noise in block-based video coding is analyzed, and a post-processing method based on the analysis is presented for reducing the quantization noise by using a wavelet transform(WT). In the proposed method, the quantization noise is considered as the sum of a blocking noise expressed as a deterministic profile and the random remainder noise. Each noise is removed in a viewpoint of image restoration using a 1-D WT, which yields a regularized differentiation. The blocking noise first is reduced by weakening the strength of each blocking noise component that appears as an impulse in the first scale wavelet domain. The impulse strength estimation is performed using median filter, quantization parameter(QP), and local activity. The remainder noise, which is considered as a white noise at non-edge pixels, then is reduced by soft-thresholding. The experimental results show that the proposed method yields better performance in terms if subjective quality as well as PSNR performance over VM post-filter in MPEG-4 for all test sequences of various compression ratios. We also present a fast post-processing in spatial domain equivalent to that in wavelet domain for real-time application.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.1
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• pp.51-60
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• 2004

Ball-end milling is one of the most common manufacturing processes for the parts with sculptured surface. However, the conventional roughness model is not suitable for the evaluation of surface texture and roughness under highly efficient machining conditions. Therefore, a different approach is needed for the accurate evaluation of machined surface. In this study, a new method, named ‘Ridge method’, is proposed for the effective prediction of the geometrical roughness and the surface topology in ball-end milling. Theoretical analysis of a machined surface texture was performed considering the actual trochoidal trajectories of cutting edge. The characteristic lines of cut remainder are defined as three-types of ‘Ridges’ and their mathematical equations are derived from the surface generation mechanism of ball-end milling process. The predicted results are compared with the results of conventional method. The agreement between the results predicted by the proposed method and the values calculated by the simulation method shows that the analytic equations presented in this paper are useful for evaluating a geometrical surface roughness of ball -end milling process.

• Journal of Korea Multimedia Society
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• v.16 no.10
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• pp.1163-1170
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• 2013

Digital watermarking techniques have been used as one of the means for copyright protection and authentication of multimedia data. Conventional Chinese Remainder Theorem(CRT)-based spatial domain watermarking techniques do not perform well under JPEG compression. However, it is seen that the CRT-based watermarking technique in Discrete Cosine Transform(DCT) domain performs well for JPEG compression. In this paper, an improved CRT-based image watermarking method in the DCT domain is proposed. The proposed method provides better robustness which decreases changes of absolute difference of residues against rounding errors due to DCT conversion and various attacks. Experimental results show that the proposed method has a good robustness against various attacks compared with the conventional CRT-based watermarking in DCT domain.

• Education of Primary School Mathematics
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• v.14 no.3
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• pp.317-328
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• 2011

We analyzed errors committed by Korean prospective elementary teachers in finding and interpreting quotient and remainder within measurement division of fractions. 65 prospective elementary teachers were participated in this study. They solved a word problem about measurement division of fractions. We analyzed solutions of all participants, and interviewed 5 participants of them. The results reveal many of these prospective teachers could not tell what fractional part of division result means. Thses results suggest that teacher preparation program should emphasize interpreting calculation results within given situations.