• 한국지능시스템학회논문지
• /
• 제21권4호
• /
• pp.442-448
• /
• 2011

이동 로봇의 위치인식 기술을 위하여 SLAM(Simultaneous Localization and Mapping)에 관한 많은 연구가 진행되고 있다. 본 논문에서는 시야각이 넓은 어안렌즈를 장착한 단일 카메라를 사용하여 천장의 특징점을 이용한 자기위치 인식에 관한 방안을 제시한다. 여기서는 어안렌즈 기반의 비전 시스템이 가지는 왜곡 영상의 보정, SIFT(Scale Invariant Feature Transform) 기반의 강인한 특징점을 추출하여 이전 영상과 이동한 영상과의 정합을 통해 최적화된 영역 함수를 도출하는 과정, 그리고 기하학적 적합모델 설계 등을 제시한다. 제안한 방법을 실험실 환경 및 복도 환경에 적용하여 그 유용성을 확인한다.

• Journal of Electrical Engineering and Technology
• /
• 제9권2호
• /
• pp.695-706
• /
• 2014

Partial discharge (PD) measurements have emerged as a dominant investigative tool for condition monitoring of insulation in high voltage equipment. But the major problem behind them the PD signal is severely polluted by several noises like White noise, Random noise, Discrete Spectral Interferences (DSI) and the challenge lies with removing these noise from the onsite PD data effectively which leads to preserving the signal for feature extraction. Accordingly the paper is mainly classified into two parts. In first part the PD signal is artificially simulated and mixed with white noise. In second part the PD is measured then it is subjected to the proposed denoising techniques namely Translation Invariant Wavelet Transform (TIWT). The proposed TIWT method remains the edge of the original signal efficiently. Additionally TIWT based denoising is used to suppress Pseudo Gibbs phenomenon. In this paper an attempt has been made to review the methodology of denoising the PD signals and shows that the proposed denoising method results are better when compared to other wavelet-based approaches like Fast Fourier Transform (FFT), Discrete Wavelet Transform (DWT), by evaluating five different parameters like, Signal to noise ratio, Cross-correlation coefficient, Pulse amplitude distortion, Mean square error, Reduction in noise level.

• 전자공학회논문지C
• /
• 제35C권2호
• /
• pp.71-79
• /
• 1998

In this paper, we propose a new mART(modified ART) neural network by combining the winner neuron definition method of SOM(self-organizing map) and the real-time adaptive clustering function of ART(adaptive resonance theory) and construct it in a modular structure, for the purpose of organizing the feature maps of three dimensional targets. Being constructed in a modular structure, the proposed modular mART can effectively prevent the clusters from representing multiple classes and can be trained to organze two dimensional distortion invariant feature maps so as to recognize targets with three dimensional distortion. We also present the recognition result and self-organization perfdormance of the proposed modular mART neural network after carried out some experiments with 14 tank and fighter target models.

• 천문학회보
• /
• 제42권2호
• /
• pp.78.3-78.3
• /
• 2017

The positions of galaxies in comoving Cartesian space varies under different cosmological parameter choices, inducing a redshift-dependent scaling in the galaxy distribution. The shape of the two-point correlation of galaxies exhibits a significant redshift evolution when the galaxy sample is analyzed under a cosmology differing from the true, simulated one. In our previous works, we can made use of this geometrical distortion to constrain the values of cosmological parameters governing the expansion history of the universe. This current work is a continuation of our previous works as a strategy to constrain cosmological parameters using redshift-invariant physical quantities. We now aim to understand the redshift evolution of the full shape of the small scale, anisotropic galaxy clustering and give a firmer theoretical footing to our previous works.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• 제9권1호
• /
• pp.224-241
• /
• 2015

Multiview plus depth (MVD) videos are widely used in free-viewpoint TV systems. The best-known technique to determine depth information is based on stereo vision. In this paper, we propose a novel local stereo matching algorithm which is radiometric invariant. The key idea is to use a combined matching cost of intensity and gradient based similarity measure. In addition, we realize an adaptive cost aggregation scheme by constructing an adaptive support window for each pixel, which can solve the boundary and low texture problems. In the disparity refinement process, we propose a four-step post-processing technique to handle outliers and occlusions. Moreover, we conduct stereo reconstruction tests to verify the performance of the algorithm more intuitively. Experimental results show that the proposed method is effective and robust against local radiometric distortion. It has an average error of 5.93% on the Middlebury benchmark and is compatible to the state-of-art local methods.

• 대한전자공학회논문지
• /
• 제25권7호
• /
• pp.836-843
• /
• 1988

For the efficient recognition of Korean alphabets, a new procedure which is applicable for the generation of phase filters with reduced resolution requirements and capable of implementing distortion tolerant pattern recognition is proposd. The performance of these filters and their advantages for Korean alphabets recognition is demonstrated.

• 한국컴퓨터정보학회논문지
• /
• 제11권1호
• /
• pp.283-292
• /
• 2006

최근 보안관련 기술에 대한 관심이 높아지고 있으며, 보안 취약성을 극복하고자 노력들이 진행되고 있다. 온라인 사용자에 대한 인증도 생체 정보인 지문을 통한 방법들이 모색되고 있는 실정이다. 본 연구에서는 온라인 사용자에 대한 인증을 위한 지문인식 시스템으로 회전에 무관한 지문인식 시스템을 설계 구현하였다. 지문 이미지의 전처리 과정, 특징점 추출을 통한 정합 과정에 초점을 두었으며, 기존 연구에서 제시된 회전에 무관한 지문 인식시스템에서 처리시간과 인식률을 개선하였다. 또한 방향성 라플라시안 필터를 적용하여 기존 연구의 전처리 과정에서 발생하는 잡음, 왜곡 등의 문제들을 개선할 수 있었다.

• Journal of Power Electronics
• /
• 제15권1호
• /
• pp.268-277
• /
• 2015

In this paper, a dual-converter three-phase pulse width modulation (PWM) rectifier based on unbalanced one-cycle control (OCC) strategy is proposed. The proposed rectifier is used to eliminate the second harmonic waves of DC voltage and distortion of line currents under unbalanced input grid voltage conditions. The dual-converter PWM rectifier employs two converters, which are called positive-sequence converter and negative-sequence converter. The unbalanced OCC system compensates feedback currents of positive-sequence converter via grid negative-sequence voltages, as well as compensates feedback currents of negative-sequence converter via grid positive-sequence voltages. The AC currents of positive- and negative-sequence converter are controlled to be symmetrical. Thus, the workload of every switching device of converter is balanced. Only one conventional PI controller is adopted to achieve invariant power control. Then, the parameter tuning is simplified, and the extraction for positive- and negative-sequence currents is not needed anymore. The effectiveness and the viability of the control strategy are demonstrated through detailed experimental verification.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2003년도 춘계종합학술대회
• /
• pp.255-258
• /
• 2003

디지털화 된 의료영상에서의 데이터 인증 및 변형 여부의 판별을 위해서 디지털 워터마킹을 사용한다. Fourier변환과 Log-Polar변환을 이용한 Fourier-Mellin기법은 영상의 RST변환에 불변한 특징을 가진다. 하지만 실질적인 구현을 위해서는 화소위치가 일치하지 않는 것에 따라 영상값을 보간해야 하는 것과 그에 따른 워터마크의 데이터 손실, 계산량 증가, 원영상의 화질 저하를 해결해야한다. Polar좌표 변환의 손실을 없애기 위해서 Look up table을 사용하였다. 진단이후, 의료영상의 ROI 영역을 중심으로 Polar좌표 변환과 Discrete fourier변환을 하였다. 주파수 진폭성분의 대칭성을 유지하면서, 가우시안 분포의 랜덤 벡터와 이진 영상을 워터마크로 삽입하여 다양한 조건 하에서의 결과를 관찰하였다.

• 천문학회보
• /
• 제42권1호
• /
• pp.52.2-53
• /
• 2017

We develop a methodology to use the redshift dependence of the galaxy 2-point correlation function (2pCF) as a probe of cosmological parameters. The positions of galaxies in comoving Cartesian space varies under different cosmological parameter choices, inducing a redshift-dependent scaling in the galaxy distribution. This geometrical distortion can be observed as a redshift-dependent rescaling in the measured 2pCF. The shape of the 2pCF exhibits a significant redshift evolution when the galaxy sample is analyzed under a cosmology differing from the true, simulated one. Other contributions, including the gravitational growth of structure, galaxy bias, and the redshift space distortions, do not produce large redshift evolution in the shape. We show that one can make use of this geometrical distortion to constrain the values of cosmological parameters governing the expansion history of the universe. This method could be applicable to future large scale structure surveys, especially photometric surveys such as DES, LSST, to derive tight cosmological constraints. This work is a continuation of our previous works as a strategy to constrain cosmological parameters using redshift-invariant physical quantities.