• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.115-117
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• 2001

A percentage current differential relaying algorithm is widely used for bus protection. However, it may maloperate external faults with CT saturation. This paper proposes a percentage current differential relaying algorithm for bus protection using CT saturation detecting algorithm. The CT saturation detecting algorithm uses difference of secondary current of CT and detects CT saturation. The proposed method distinguishes percentage differential relay operation caused by faults from percentage differential relay operation caused by CT saturations.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3207-3209
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• 2000

X-ray CT(Computed Tomography) has been a good modality for non-invasive diagnosis and recently, Conventional CT has been replaced rapidly with Spiral CT in recent. In X-ray CT, spiral scanning has various advantages such as better image quality, reduced scan time (in a single breath-hold), a lower x-ray dose. But, it requires very fast and high performance image processing system to reconstruct slice images from spiral scanning. This paper describes the fast image reconstruction techniques with filtered back projection from the viewpoints of fast algorithm as well as hardware implementation for real-time imaging.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.928-930
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• 2020

본 논문은 인공지능 플랫폼 기반의 요로결석 진단을 위한 CT 영상 데이터 자동판독 시스템에 대해 기술하고자 한다. 제안한 시스템은 웹 기반의 플랫폼을 기반으로 하며, 인공지능 기반의 진단 알고리즘을 장착하여 빠르게 요로결석 환자의 스크리닝에 목적을 두고 있다. 병원정보시스템의 PACS와 EMR과 연계와 Deep learning 진단 알고리즘을 적용한 요로결석 자동판독 시스템을 개발하였다. 특히, 기 구축된 인공지능 플랫폼을 통해 추출한 데이터셋을 기반으로 진단 알고리즘 개발 방법과 수행 결과를 보인다. 제안한 시스템은 요로결석 진단과 수술여부에 의사결정지원 시스템으로 임상에서 활용될 것으로 기대하고 있다.

• Journal of the Korean Society of Radiology
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• v.15 no.1
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• pp.21-28
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• 2021

Computed tomography (CT) has the problem of having more radiation exposure compared to other radiographic apparatus. There is a low-dose imaging technique for reducing exposure, but it has a disadvantage of increasing noise in the image. To compensate for this, various noise reduction algorithms have been developed that improve image quality while reducing the exposure dose of patients, of which the median modified Wiener filter (MMWF) algorithm that can be effectively applied to CT devices with excellent time resolution has been presented. The purpose of this study is to optimize the mask size of MMWF algorithm and to see the excellence of noise reduction of MMWF algorithm for existing algorithms. After applying the MMWF algorithm with each mask sizes set from the MASH phantom abdominal images acquired using the MATLAB program, which includes Gaussian noise added, and compared the values of root mean square error (RMSE), peak signal-to-noise ratio (PSNR), coefficient correlation (CC), and universal image quality index (UQI). The results showed that RMSE value was the lowest and PSNR, CC and UQI values were the highest in the 5 x 5 mask size. In addition, comparing Gaussian filter, median filter, Wiener filter, and MMWF with RMSE, PSNR, CC, and UQI by applying the optimized mask size. As a result, the most improved RMSE, PSNR, CC, and UQI values were showed in MMWF algorithms.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.281-288
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• 2022

In this study, four algorithms (Soft, Standard, Detail, Bone) were used for general CT scan (Before MAR) images and MAR (After MAR) images for patients with metal implants inserted into the hip joint. was applied to compare and analyze Noise, SNR, and CNR to find out the optimal algorithm for quantitative evaluation. As the analysis method, Image J program, which can calculate image analysis and area and pixel values on the image reconstructed with four algorithms, was used. In order to obtain Noise, SNR, and CNR, the HU mean value and HU SD value were obtained by designating the bone (ischium) closest to the metal implant in the image for the measurement site, and the background noise was the surrounding muscle. The region of interest (ROI) was equally designated as 15 × 15 mm in consideration of the size of the bone, and the values of SNR and CNR were calculated according to the given equation. As a result, for noise, After MAR and Soft algorithms showed the lowest noise, and SNR and CNR showed the highest for Before MAR and Soft algorithms. Therefore, the soft algorithm is judged to be the most appropriate algorithm for metal implant hip joint CT.

• Proceedings of The KACE
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• 2018.08a
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• pp.3-6
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• 2018

2015 개정 교육과정에 따라 2019년 3월부터 초등학교 5~6학년 학생을 대상으로 소프트웨어 교육이 실시된다. 궁극적인 소프트웨어 교육의 목표는 컴퓨팅 사고력을 갖춘 창의 융합형 인재를 양성하는 것이다. 이를 위해 초등학교에서는 알고리즘과 프로그래밍의 체험을 통해 소프트웨어 기초 소양을 함양하는 것을 목표로 한다. 이러한 컴퓨팅 사고력을 수업에 효과적으로 적용하기 위해 전용주(2017)는 소프트웨어 및 컴퓨팅에 관련된 사고과정과 원리를 실생활의 소재와 관련지어 창의적이고 능동적으로 그 해결방안을 구현해가는 과정으로 제시할 수 있는 수업 구성 원리인 CT-CPS 수업 모형을 개발하였다. 또한 교육부는 2015 개정 교육과정 실시 전, 소프트웨어 교육을 위한 선도학교를 전국에 지정하여 운영하였다. 선도학교에서의 소프트웨어 교육과정을 분석한 결과 주로 컴퓨팅 사고력의 구성요소 중 알고리즘과 자동화에 초점이 맞춰져 있었다. 엔트리와 스크래치와 같은 블록 프로그래밍 도구를 사용한 코딩교육과 로봇교육을 주로 실시했고, 실제 문제에 대한 학생들이 자료를 직접 다루는 시간은 찾아보기 힘들었다. 컴퓨팅사고력 향상을 위해서는 학생들이 실제 자료를 수집, 분석, 표현해보는 활동이 반드시 필요하다. 이에 본 연구에서 NetsBlox을 활용하고자 한다. NetsBlox는 학생들에게 익숙한 블록형 프로그래밍 도구로 실제 데이터를 온라인상에서 쉽게 받아와서 수집, 분석, 표현을 하게 도와주는 역할을 한다. 따라서 본 연구에서는 초등학생을 위한 NetsBlox를 활용한 CT-CPS기반 프로그래밍 수업을 설계하고자 한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.11
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• pp.1873-1878
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• 2007

Current differential relays may maloperate during magnetic inrush and over-excitation because a significant differential current is produced. To prevent maloperation, the relays adopt some harmonic components included in the differential current. The harmonic restraints may increase the security of a relay but cause the operating time delay of a relay when an internal fault occurs. Moreover, the operating time delay is more increased if a current transformer (CT) is saturated. This paper describes a current differential relaying algorithm for power transformer protection with a compensating algorithm for the secondary current of a CT. The comparative study was conducted with and without the compensating algorithm. The performance of the proposed algorithm was investigated when the measurement CT (C400) and the protection CT (C400) are used. The proposed algorithm can compensate the distorted current of a CT and thus reduce the operating time delay of the relay significantly for an internal fault with CT saturation.

• The Korean Journal of Applied Statistics
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• v.12 no.2
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• pp.537-551
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• 1999

방출형 토모그래피와는 다르게, 토과형 토모그래피를 위한 통계적 알고리즘들은 매우 늦은 수렴속도와 엄청난 계산시간을 감수해야 했다. 그 주된 이유는 Lange-Carson 모형에 기초한 EM 알고리즘을 사용하고 있기 때문인데, 최근 GCA 기법의 등장으로 계산 시간을 현저히 단축할 수 있는 가능성이 제공되었다. 그러나 GCA 알고리즘은 우도의 단조중가성을 만족시키기 위해 부가적인 계산시간을 희생해야만 한다. 이에 본 연구에서는 프로그래밍이 간편하며, 처리시간이 짧고, 자체로 우도의 단조증가성을 만족하는 투과형 토모그래피를 위한 재구성 알고리즘을 제안한다.

• Journal of Digital Convergence
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• v.16 no.2
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• pp.19-26
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• 2018

We proposed a numerical calculation of the proportion of necrotic cells in pulmonary segmentation, pulmonary vessel segmentation lung disease site for diagnosis of lung disease from chest CT images. The first step is to separate the lungs and bronchi by applying a three-dimensional labeling technique from a chest CT image and a three-dimensional region growing method. The second step is to divide the pulmonary vessels by applying the rate of change using the first order polynomial regression, perform noise reduction, and divide the final pulmonary vessels. The third step is to find a disease prediction factor in a two-step image and calculate the proportion of necrotic cells.

• Journal of radiological science and technology
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• v.47 no.1
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• pp.39-48
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• 2024

In this study, we optimized the FNLM algorithm through a simulation study and applied it to a phantom scanned by low-dose CT to evaluate whether the FNLM algorithm can be used to obtain improved image quality images. We optimized the FNLM algorithm with MASH phantom and FASH phantom, which the algorithm was applied with MATLAB, increasing the smoothing factor from 0.01 to 0.05 with increments of 0.001 and measuring COV, RMSE, and PSNR values of the phantoms. For both phantom, COV and RMSE decreased, and PSNR increased as the smoothing factor increased. Based on the above results, we optimized a smoothing factor value of 0.043 for the FNLM algorithm. Then we applied the optimized FNLM algorithm to low dose lung CT and lung CT under normal conditions. In both images, the COV decreased by 55.33 times and 5.08 times respectively, and we confirmed that the quality of the image of low dose CT applying the optimized FNLM algorithm was 5.08 times better than the image of lung CT under normal conditions. In conclusion, we found that the smoothing factor of 0.043 among the factors of the FNLM algorithm showed the best results and validated the performance by reducing the noise in the low-quality CT images due to low dose with the optimized FNLM algorithm.