• Journal of the Korean Society for Nondestructive Testing
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• v.22 no.5
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• pp.465-473
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• 2002

Images are easily corrupted by noise during the data transmission, data capture and data processing. A technical method of noise analyzing and adaptive filtering for reducing of quantum noise in radiography is presented. By adjusting the characteristics of the filter according to local statistics around each pixel of the image as moving windowing, it is possible to suppress noise sufficiently while preserve edge and other significant information required in reading. We have proposed adaptive weighted median(AWM) filters based on local statistics. We show two ways of realizing the AWM filters. One is a simple type of AWM filter, whose weights are given by a simple non-linear function of three local characteristics. The other is the AWM filter which is constructed by homogeneous factor(HF). Homogeneous factor(HF) from the quantum noise models that enables the filter to recognize the local structures of the image is introduced, and an algorithm for determining the HF fitted to the detection systems with various inner statistical properties is proposed. We show by the experimented that the performances of proposed method is superior to these of other filters and models in preserving small details and suppressing the noise at homogeneous region. The proposed algorithms were implemented by visual C++ language on a IBM-PC Pentium 550 for testing purposes, the effects and results of the noise filtering were proposed by comparing with images of the other existing filtering methods.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.23-35
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• 2020

This study is based on prior research cases on workplace learning, which had a significant impact on corporate research. To improve problem solving and supplementing ability by keeping the opportunity to participate in workplace learning for the weak small business owners and to strengthen opportunities for practical growth, and to propose education, policy and institutional windowing. Therefore, to establish the relationship between small business owners' workplace learning, job satisfaction, and service quality, a research hypothesis was set in the background of prior research and empirical analysis was conducted. The results from 203 questionnaires were analyzed with SPSS 18.0 program. As an analytical result, first, workplace learning had a partial positive (+) impact on job satisfaction. Second, workplace learning had a partial positive (+) impact on service quality. Third, in the relationship between workplace learning and service quality, job satisfaction played a full mediating role. From this, it was found that formal learning, the subfactor of workplace learning did not have an impact on job satisfaction and service quality, as subtitle of educational environment including offsite training and self education, systematization, and structuralization depending on the poor environment of small enterprises. Therefore, it was found that small enterprises' poor environment was revealed from the managerial, economic and social perspectives and to compensate such defect, educational, policy, and institutional strategies to strengthen the opportunity for growth and development of small enterprises can be suggested to the governmental agencies or local governments. Despite the significant results of this study, there may be limitations. Therefore, further studies should be conducted in various fields with various samples in the future, and further studies should be conducted in academic and practical relationships that can improve the service quality and management performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.5
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• pp.993-1000
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• 2017

When the availability of embedded device is considered, combined countermeasure such as first-order masking and hiding countermeasures is quite attractive because the security and efficiency can be provided at the same time. Especially, combined countermeasure can be applied to the confusion and diffusion layers of the first and last rounds in order to provide the efficiency. Also, the middle rounds only employs first-order masking countermeasure or no countermeasure. In this paper, we suggest a novel side channel analysis with low complexity in the output of diffusion layer. In general, the attack target cannot be set to the output of diffusion layer owing to the high complexity. When the diffusion layer of block cipher is composed of AND operations, we show that the attack complexity can be reduced. Here, we consider that the main algorithm is SEED. Then, the attack complexity with $2^{32}$ can be reduced by $2^{16}$ according to the fact that the correlation between the combination of S-box outputs and that of the outputs of diffusion layer. Moreover, compared to the fact that the main target is the output of S-box in general, we demonstrate that the required number of traces can be reduced by 43~98% in terms of simulated traces. Additionally, we show that only 8,000 traces are enough to retrieve the correct key by suggested scheme, although it fails to reveal the correct key when performing the general approach on 100,000 traces in realistic device.

• Journal of KIISE:Information Networking
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• v.30 no.5
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• pp.656-667
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• 2003

Congestion control is a key task in reliable multicast along with error control. However, existing tree-based congestion control schemes such as MTCP and TRAMCC are designed for one-to-many reliable multicast and have some drawbacks when they are used for many-to-many reliable multicast. We propose an efficient congestion control mechanism, TMRCC, for tree-based many-to-many reliable multicast protocols. The proposed scheme is based on the congestion windowing mechanism and a rate controller is used in addition. The feedback for error recovery is exploited for congestion control as well to minimize the overhead at the receivers. The ACK timer and the NACK timers are set dynamically reflecting the network condition changes. The rate regulation algorithm in the proposed scheme is designed to help the flows sharing the same link to achieve the fair share quickly The performance of the proposed scheme is evaluated using ns-2. The simulation results show that the proposed scheme outperforms TRAMCC in terms of intra- session fairness and shows good level of responsiveness, TCP-friendliness, and scalability. In addition, we implemented the proposed scheme by integrating with GAM that is one of many-to-many reliable multicast protocols and evaluated the performance in a laboratory-wide testbed.

• Journal of the Korean Society of Radiology
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• v.17 no.1
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• pp.131-139
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• 2023

In this study, we are purposed to find the educational effect of practical training using a 3D printed structure-based blind box on multidimensional radiographic image interpretation. The subjects were 83 (male: 49, female: 34) 2nd year radiological science students who participated in the digital medical imaging practice that was conducted for 3 years from 2020 to 2022. The learning method used 3D printing technology to print out the inside structure of the blind box designed by itself. After taking X-rays 3 times (x, y, z axis), the structure images in the blind box were analyzed for each small group. We made the 3D structure that was self-made with clay based on our 2D radiographic images. After taking X-rays of the 3D structure, it was compared whether it matches the structural image of the blind box. The educational effect for the practical training surveyed class faithfulness, radiographic image interpretation ability (attenuation concept, contrast concept, windowing concept, 3-dimensional reading ability), class satisfaction (interest, external recommendation, immersion) on a 5-point Likert scale as an anonymous student self-writing method. As a result, all evaluation items had high positive effects without significant differences between males and females. Practical education using blind boxes is a meaningful example of radiology education technology using 3D printing technology, and it is expected to be used as content to improve students' problem-solving skills and increase satisfaction with major subjects.

• Progress in Medical Physics
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• v.22 no.1
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• pp.35-41
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• 2011

For overall system test, hidden-target test have been used using film which leads to inherent analysis error. The purpose of our study is to quantify this error and to propose gel dosimeter based verification technique for 3-dimensional target point error. The phantom was made for simulation of human head and this has ability to equip 10 gel-dosimeter. $BANGkit^{TM}$ which we are able to manufacture whenever it is needed as well as to easily change the container with different shapes was used as a gel dosimeter. The 10 targets were divided into two groups based on shapes of areas with a planned 50% isodose line. All treatment and analysis was performed three times using Novalis and $BrainSCAN^{TM}$. The target point error is $0.77{\pm}0.15mm$ for 10 targets and directional target point error in each direction is $0.54{\pm}0.23mm$, $0.37{\pm}0.08mm$, $0.33{\pm}0.10mm$ in AP (anterior-posterior), LAT (lateral), and VERT (vertical) direction, respectively. The result of less than 1 mm shows that the treatment was performed through each precise step in treatment procedure. In conclusion, the 3-dimensional target point verification technique can be one of the techniques for overall system test.