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이상 유동에서 영상 복원을 위한 EIT system 회로의 안정성 평가
이보안,현종관,이헌주,김신,김경연 濟州大學校 産業技術硏究所 2001 산업기술연구소논문집 Vol.12 No.1
The EIT(Electrical Impedance Tomography) system is one of the methods for tomographv technologies. The EIT measurement is less expensive than other methods because the system is relatively simple and easy to construct compared to other methods. In this study. the real voltage values were compared to theoretical values. The rmse(root mean square error) of measured data was 2.99%. So that. this EIT system circuit was a accuracy circuit for a reconstruction algorithm.
이보안,김봉석,고민석,김경연,김신 한국원자력학회 2014 Nuclear Engineering and Technology Vol.46 No.1
An electrical resistance tomography (ERT) technique combining the particle swarm optimization (PSO) algorithm withthe Gauss-Newton method is applied to the visualization of two-phase flows. In the ERT, the electrical conductivitydistribution, namely the conductivity values of pixels (numerical meshes) comprising the domain in the context of anumerical image reconstruction algorithm, is estimated with the known injected currents through the electrodes attached onthe domain boundary and the measured potentials on those electrodes. In spite of many favorable characteristics of ERT suchas no radiation, low cost, and high temporal resolution compared to other tomography techniques, one of the majordrawbacks of ERT is low spatial resolution due to the inherent ill-posedness of conventional image reconstructionalgorithms. In fact, the number of known data is much less than that of the unknowns (meshes). Recalling that binarymixtures like two-phase flows consist of only two substances with distinct electrical conductivities, this work adopts the PSOalgorithm for mesh grouping to reduce the number of unknowns. In order to verify the enhanced performance of theproposed method, several numerical tests are performed. The comparison between the proposed algorithm and conventionalGauss-Newton method shows significant improvements in the quality of reconstructed images
이상 유동에서 영상 복원을 위한 EIT system 회로의 안정성 평가
이보안,현종관,이헌주,김신,김경연 제주대학교 산업기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.1
The EIT(Electrical Impedance Tomography) system is one of the methods for tomography technologies. The EIT measurement is less expensive than other methods because the system is relatively simple and easy to construct compared to other methods. In this study, the real voltage values were compared to theoretical values. The rmse(root mean square error) of measured data was 2.99%. So that, this EIT system circuit was a accuracy circuit for a reconstruction algorithm.
PEO가 첨가된 원형관 난류유동에서의 마찰저항 감소 측정
이보안,이동원,김신,현명택,천원기 濟州大學校 産業技術硏究所 1998 산업기술연구소논문집 Vol.9 No.2
The drag reduction by polymer additive is a well-known phenomenon and has been widely studied due to its high usefulness. In this study, in order to obtain the fundamental data on the drag reduction by polymer additive. we measured the friction factors in the polymer added turbulent flow through a circular pipe for Reynolds number ranging 10000-50000. As polymer additive, PEO (polyethylene oxide: molecular weight 4 x l0^(6)) was used. We also performed the experiments varying the concentration of PEO from 3 to 24 wppm to investigate the effect of the PEO concentration on the drag reduction. We observed more than 25% drag reduction under the above experimental conditions and the most effective drag reduction was found at 6 wppm (31% drag reduction).
보안공학연구지원센터(IJSIA) 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.10
Watermarking technique provides the possibility for copyright protection. Discrete cosine transform (DCT) is the most popular tool used in watermarking algorithm. But the watermarking algorithm based on DCT is not the most ideal choice in terms of the complexity and robustness. All phase discrete cosine biorthogonal transform (APDCBT) owns the characteristics of high frequency attenuation and good applications in image coding, image denoising and other fields of digital image processing, which provides an efficient method for watermarking. In this paper, a new watermarking algorithm based on APDCBT is proposed. Besides, the binary image watermark is scrambled by Arnold transform to enhance its privacy and robustness greatly in our algorithm. The watermark information is embedded in direct-current (DC) components considering DC components have much larger perceptual capacity. Compared with the DCT algorithm, the proposed algorithm has stronger robustness in embedding and extracting the watermark. Experimental results show that our algorithm can satisfy the imperceptibility and robustness very well. Furthermore, our algorithm is tested against four kinds of attacks: JPEG compression, Gaussian noise, salt & pepper noise and rotation.
보안공학연구지원센터(IJSIA) 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.10
The composition of the relationships between Scientists and Employers are formal relationship and informal relationship. The asset nature of these two relationships determines the governance structure of the organization. Based on the theory of the transaction cost and institutionalism, Author develops repeated game models and argues that the governance structure of Little Science should be the combination of non-integration and non-relational contract. Author shows that the governance structure of China’s Little Science is improperly built, which should be rebuilt by de-administrative.
A Comparative Study of the Proposed National Cyber-terror Prevention Act
보안공학연구지원센터(IJSIA) 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.10
Cybercrimes and cyber-terror attacks disturb national order, and can result in cyber warfare that ruins people’s happiness, and destroys national security and people’s safety. Cyber-terror attacks have occurred in the 7.7 DDoS attack, the 3.4 DDoS attack, the attack that paralyzed the NH Computer Network, the Jungang Ilbo Incident, The APT attack against KBS, MBC, YTN, the Shinhan Bank, and the NH Bank to stop computer operation. In 2013, the website of Cheongwadae was attacked through the 6.25 cyber-terror attack. In January, 2014, confidential personal information of approximately 85 million customers of 3 credit card companies of the Lotte Card, KB Kookmin Card and the NH Card was stolen. There is a need for real-time response system that can respond in real-time cyber-hacking attacks. However, acts and regulations are insufficient, the budget and the policies and institutions of national cyber security is needed to support the organization. In this study, we analyze and compare the two Cyber-terro Prevention Act was proposed to the National Assembly. And, triggered alarm in the control tower and cyber need for cyber security against cyber crisis.