• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4B
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• pp.715-724
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• 2000

This Paper presents 3-D subband filter banks which are effective for progressive and lossless compression of volumetric images. For such a purpose, ORT(Overlapping Rounding Transform), applied so far to 1-D losslesssubband filter banks, is now used to implement two types of 3-D lossless subband filter banks: separable andnon-separable types. Separable fiter banks are implemented form applying 1-D lossless filter banks consecutively.Non-separable later banks are developed by expanding the 1-D ORT into 3-D one. In particular, the proposed ORT based 3-D non-separable filter banks generalizes the 3-D HINT(Hierarchical INTerpolation) algorithm.Through the experiment comparisons on various volumetric medical images, we prove that the proposedseparablefnon-separable filter banks perform better, in terms of compression ratio (first order entropy), than theother lossless compression techniques such as block based transform and conventional 3-D HINT.

• Journal for History of Mathematics
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• v.17 no.4
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• pp.37-44
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• 2004

Homological algebra has emerged and developed since 1950s. However, in 1890's Hilbert investigated the resolutions in his Syzygy Theorem which is a vital ingredient in homological algebra. In 1956 Serre has proved the finite global dimension of regular local rings. His result give a basic tool in homological algebra. This paper also deals with the depth formula that was raised by Auslander in 1961.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.9
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• pp.927-938
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• 1992

In 1-D subband coding system, a quadrature mirror filter (QMF) pair can be used to split a signal into two subbands and to reconstruct the original signal. In this paper, a pair of 1-D reconstruction filter for the subband coding system is introduced and a coding technique with classified vector quantization, based on energy distributions, for 16 subband images is presented. As computer simulation results show that the method can give similar perceptual quality with bit rate reduced by $20{\sim}30%$ of that of ordinary vector quantization.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2458-2467
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• 1994

This paper proposes a new design method for obtaining the impulse responses which satisfy the prescribed conditions designing for maximally flat FIR lowpass filters and highpass filters. The bandpass filters and band-reject filters have been directly derived from the addition and subtraction of impulse responses of a lowpass filter and a highpass filter. The two-dimensional maximally flat FIR lowpass filter, highpass filters, bandpass filters and band-reject filters with zero-phase have been designed by transforming the impulses of the one-dimensional filters designed in this research, which do not destroy lines and edges at the image signal processing.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.3 no.2
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• pp.31-38
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• 2010

It is difficult to design accurately the bandgap of metamaterial depending on metamaterial pattern and array configuration. In this paper, we propose a design method for the wanted bandgap frequency using any metamaterial pattern in 2 dimensional array. Metamaterial structure is consisted of periodic array. Therefore the calculation area in FDTD(finite difference time domain) method can be reduced by applying the periodic boundary condition to 2-D metamaterial array. The method for design and calculation the L and C values by using 2-D is also considered. So it can be designed more accurately and rapidly. For example, we designed metamaterial square pattern array in 5 GHz, and compared with the 1-D metamaterial pattern using analysis method in microstrip line. As a result, we found that the accuracy of this proposed method can be incresed to 14.7%.

• The Journal of the Acoustical Society of Korea
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• v.24 no.7
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• pp.395-401
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• 2005

In this paper, the high-band codec for bandwidth scalable wideband speech codec is proposed. The wideband input speech signal is separated into low-band signal and high-band signal, and the low-band signal is encoded by the standard narrow-band speech codec and the high-band signal is encoded by the proposed codec. In the high-band codec. the signal is transformed into frequency domain by MLT on a subframe basis, and MLT coefficients are splitted into magnitude and sign for quantization. The magnitudes of MLT coefficients are arranged into several time-frequency bands and each band is quantized in 2D-DCT domain, where the low-band information is utilized for better performance. The sign of MLT coefficient is quantized based on a priority selection process with the weighting measurement. The objective and subjective performance of wideband speech codec including the proposed high-band codec is measured, and it is confirmed that the proposed codec has better performance than 32kbps G.722.1.

• Proceedings of the Acoustical Society of Korea Conference
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• autumn
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• pp.81-84
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• 2004

패킷망을 통한 음성 통신이 발달됨에 따라 패킷 스위칭 채널 환경에서 계층적 구조를 가지는 광대역 음성 부호화기의 개발에 대한 요구가 늘어나고 있다. 본 논문에서는 이러한 차세대 패킷 전화용 광대역 음성 부호화기의 상위 대역에 대해서 효율적인 양자화 방법을 제안한다. 먼저 전체 프레임을 다수의 짧은 부프레임으로 구분하고, 각각의 부프레임에 MLT(Modulated Lapped Transform)변환을 적용하여 주파수 영역으로 변환하여 2차원 구조의 데이터 행렬을 생성한다. 이러한 2차원 구조의 데이터를 크기와 부호로 분리하고, 크기는 2차원 DCT를 사용하여 시간과 주파수 영역에서의 신호 압축을 동시에 얻을 수 있게 하였다. 이와 같은 새로운 구조를 활용하여 기존의 방법보다 Energy Compaction 효과를 높이고 양자화 성능을 향상시킬 수 있었다. 또한 Core Layer의 부호화된 파라미터를 상위 대역의 양자화에 이용함으로써 그 성능을 향상시킬 수 있는 방법을 제안한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.5 s.305
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• pp.11-18
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• 2005

In this paper, we proposed a video watermarking algerian based on wavelet transform using statistical characteristic of video according to the energy distribution and the spread spectrum technique. In the proposed method, the original video is splitted by spatial difference metric and classified into the motion region and the motionless region according to the motion degree. The motion region is decomposed into 3-levels using 3D DWT and the motionless region is decomposed into 2-levels using 2D DWT The baseband of the wavelet-decomposed image is not utilized because of the image quality. So that the standard deviation of the highest subband coefficients except for the baseband is used to determine the threshold. Binary video watermarks preprocessed by the random permutation and the spread spectrum technique are embedded into selected coefficients. In computer experiments, the proposed algorithm was found to be more invisible and robust than the conventional algorithms.

• Proceedings of the Safety Management and Science Conference
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• 2009.11a
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• pp.639-643
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• 2009

세계 각국은 새로운 유비쿼터스 환경변화에 맞추어 전략적 차원에서 u-IT에 대한 연구와 다양한 프로젝트를 추진 중이다. 특히 유비쿼터스를 지역수준으로 적용 시 지역 구성원들의 삶의 질이 향상되고 편익을 직접적으로 체감할 수 있는 효과가 있다. 유비쿼터스 환경의 중심 기술 중 하나인 RFID는 대역별로 다른 특징을 가지고 있어 단일 대역 RFID는 제약조건이 있으며, 이를 극복하고 보다 입체적인 정보와 서비스를 제공하기 위하여 여러 대역의 RFID를 통합하는 기술이 필요하다. 따라서 본 연구에서는 새로운 u-City 서비스 모델로써 u-Zone 서비스 구축 시에 필요한 13.56MHz와 2.45GHz 주파수 대역의 듀얼밴드 RFID Manager를 개발한다. RFID Manager는 u-Zone 서비스의 임베디드 하드웨어인 Base Station에 탑재하는 응용 소프트웨어로서 리더에서 입력되는 정보를 u-Zone 통합 서버 시스템에 전달하는 역할을 한다.

• Korean Journal of Optics and Photonics
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• v.20 no.4
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• pp.211-216
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• 2009

Much research into two-dimensional (2-D) photonic crystal (PC) structures has been conducted for realization of ultrasmall optical integrated circuits. A 2-D silicon (Si) PC slab structure with air cladding (n=1) is one of the representative structures in 2-D PCs. While air-clad Si PC slab structures have good optical characteristics, their suspension in air can lead to mechanical weakness, making integration with some optical devices difficult. In this paper, we propose improving the mechanical robustness of PC structure by developing a 2-D Si PC structure with symmetric silica cladding (n=1.44) and comparing its optical properties to that of the air-clad structure. First, we investigate the optical properties of a 2-D Si PC slab structure with air cladding by using a 3-D finite difference time domain method. We determined that a photonic bandgap of 330 nm and a non-leaky propagating bandwidth of 100 nm in the optical communication range are possible. Next, we investigate the optical properties of 2-D Si PC slab structures with silica cladding. Even though the refractive index of the silica cladding is higher than that of air, we developed a silica-clad structure with good optical properties: a photonic band gap of approximately 230 nm and a non-leaky propagating bandwidth of 90 nm, comparable to that of the air-clad PC structures.