• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.579-584
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• 2001

컴퓨터 그래픽스 기술을 이용한 응용분야가 증가함에 따라 물체의 사실적인 모델에 대한 요구가 증가되고 있다. 모델링 시간이 많이 필요한 기존의 3차원 모델링 툴 외에 최근에 사용자의 스케치에 기반한 모델링 방법과 영상기반 모델링, 3차원 스캐너가 발표되었지만, 정확성이 떨어지거나 고가의 장비를 필요로 하는 단점이 있다. 본 논문에서는 정육면체 프레임과 광평면(light plane) 프로젝터, 카메라를 이용한 물체의 3차원 구조 복원 시스템을 제안하고, 실험을 통하여 모델링의 정확도를 분석한다.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2903-2905
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• 2005

많은 경우, 부분 손상된 얼굴 영상을 복원해야 할 필요가 있다. 대표적인 예로는 감시카메라에 찍힌 범인의 얼굴 영상이 이에 속한다. 이런 경우 얼굴의 중요한 부분이 가려져 있기 때문에 자동 얼굴 인식 시스템이나 사람의 관찰로는 그 부분을 인식하기는 매우 어렵다. 이 논문에서는 어려움을 극복하기 위해 새롭게 개발된 SVDD기반 노이즈 제거 기법을 부분 손상된 얼굴 영상에 적용한 문제를 고려해 보았다.

• Proceedings of the Korea Information Processing Society Conference
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• 2018.10a
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• pp.193-195
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• 2018

홍채코드는 홍채의 정보를 이진코드로 표현함으로써 홍채정보를 보호하는 방법이다. 이러한 방법은 현재 홍채인식 시스템에서 표준으로 채택된 기술이다. 본 논문에서는 1-D 가버 필터를 사용하여 홍채 코드로부터 역공학적 방법을 사용하여 홍채영상을 복원하고, 복원된 홍채 영상과 기존의 홍채영상의 인식 결과를 통해 홍채 인식에 대한 취약성을 연구한다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10c
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• pp.568-570
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• 2002

무선 전자상거래(M-Commerce)는 이동 통신 네트워크 기술과 무선 단말기를 기반으로 하여 언제 어디서나 필요한 시점에서 행할 수 있는 상거래를 의미하며 이때, 전자지불 방식의 하나인 전자화폐는 실물화폐와 유사한 성질을 만족해야 한다. 본 논문에서는 이산대수문제에 기반한 메타-메시지 복원과 은닉 서명 기법을 이용하여 전자화폐가 이중사용, 돈 세탁 그리고 불법 무기 구매 둥 부정한 수단으로 악용되었을 때 신뢰센터가 사용자의 익명성을 제어하고 지불 금액을 다시 복원할 수 있는 알고리즘을 제안한다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2021.11a
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• pp.205-205
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• 2021

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.3
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• pp.201-210
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• 1996

In this paper, we analyzed performance of a symbol timing recovery scheme for 16QAM Radio system. As a symbol timing recovery scheme, both maximum amplitude method(MAM) and wave difference method(WDM) are analyzed employing a pulse shaping filter, such as raised cosine filter(RCF) and nonlinear filter(NLF). Simulation result shows that the jitter performance of MAM or WDM using NLF is better than that using square root RCF. In order to estimate and compensate for the Rayleigh fading PSAM(Pilot Symbol Assisted Modulation) and space diversity are also employed. Consequently, BER performance of about $10^{-4}$ is obtained for $E_b/N_o$= 20 dB.

• Journal of the Korea Society of Computer and Information
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• v.6 no.4
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• pp.104-109
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• 2001

In this paper, we designed a 3D shape measuring system with high speed and high measurement resolution using line-shaped sine stripes of a LCD projector We proposed an effective method to improve measurement efficiency for a 3D shape measuring system by finding the deficient shape information areas and recovering the shape information efficiently. We experimentally confirmed the improvement of measurement efficiency. Deficient shape information areas can be inevitably existed in a acquired image caused by the camera view angle and surface shapes of an object. The measurement efficiency is turned out to be improved by extracting these shadow areas and recovering the shape information efficiently using both a variable rated normalization and a variable sized phase recovering windows.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.55-62
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• 2023

Radio waves must pass through the unstable atmosphere for successful wireless data transmission from space to ground stations. Data link algorithms required by the International Space Data Systems Advisory Committee (CCSDS) must be capable of detecting and resynchronizing cryptographic and receiver-side errors. However, error recovery is not part of the CCSDS requirements. This paper proposes an algorithm that enables robustness and error recovery against various noises. We experimented with environments such as Gaussian, Salt, Pepper, and S&P noise through noise reduction filters, filters that improve sharpness, and EDSR. In addition, we compare similar algorithms SES Alarmed and DSES Alarmed.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.173-180
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• 2014

Compressive sensing is a new signal acquisition paradigm that enables sparse/compressible signal to be sampled under the Nyquist-rate. To fully benefit from its much simplified acquisition process, huge efforts have been made on improving the performance of compressive sensing recovery. However, concerning color images, compressive sensing recovery lacks in addressing image characteristics like energy distribution or human visual system. In order to overcome the problem, this paper proposes a new group-sparsity hard thresholding process by preserving some RGB-grouped coefficients important in both terms of energy and perceptual sensitivity. Moreover, a smoothed group-sparsity iterative hard thresholding algorithm for compressive sensing of color images is proposed by incorporating a frame-based filter with group-sparsity hard thresholding process. In this way, our proposed method not only pursues sparsity of image in transform domain but also pursues smoothness of image in spatial domain. Experimental results show average PSNR gains up to 2.7dB over the state-of-the-art group-sparsity smoothed recovery method.

• Korean Journal of Remote Sensing
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• v.39 no.6_1
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• pp.1341-1352
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• 2023

The normalized difference vegetation index (NDVI) derived from satellite images is a crucial tool to monitor forests and agriculture for broad areas because the periodic acquisition of the data is ensured. However, optical sensor-based vegetation indices(VI) are not accessible in some areas covered by clouds. This paper presented a synthetic aperture radar (SAR) based approach to retrieval of the optical sensor-based NDVI using machine learning. SAR system can observe the land surface day and night in all weather conditions. Radar vegetation indices (RVI) from the Sentinel-1 vertical-vertical (VV) and vertical-horizontal (VH) polarizations, surface elevation, and air temperature are used as the input features for an automated machine learning (AutoML) model to conduct the gap-filling of the Sentinel-2 NDVI. The mean bias error (MAE) was 7.214E-05, and the correlation coefficient (CC) was 0.878, demonstrating the feasibility of the proposed method. This approach can be applied to gap-free nationwide NDVI construction using Sentinel-1 and Sentinel-2 images for environmental monitoring and resource management.