• IEIE Transactions on Smart Processing and Computing
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• v.3 no.3
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• pp.103-109
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• 2014

This study derived the inter-conversion matrices, which can be used in heterogeneous image transcoding between the compressed images using different transforms, such as the $8{\times}8$ block discrete cosine transform (BDCT) and the one-level discrete wavelet transform (DWT). Basically, to obtain the one-level DWT coefficients from $8{\times}8$ BDCT, inverse BDCT should be performed followed by forward DWT, and vice versa. On the other hand, if the proposed interconversion approach is used, only one inter-conversion matrix multiplication makes the corresponding transcoding possible. Both theoretical and experimental analyses showed that the amount of computation of the proposed approach decreases over 20% when the inter-conversion matrices are used under specific conditions.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1166-1177
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• 2014

A new type of topology with medium-frequency-transformer (MFT) isolation for medium voltage wind power generation systems is proposed in this paper. This type of converter is a high density power conversion system, with high performance features suitable for next generation wind power systems in either on-shore or off-shore applications. The proposed topology employs single-phase cascaded multi-level AC-AC converters on the grid side and three phase matrix converters on the generator side, which are interfaced by medium frequency transformers. This avoids DC-Link electrolytic capacitors and/or resonant L-C components in the power flow path thereby improving the power density and system reliability. Several configurations are given to fit different applications. The modulation and control strategy has been detailed. As two important part of the whole system, a novel single phase AC-AC converter topology with its reliable six-step switching technique and a novel symmetrical 11-segment modulation strategy for two stage matrix converter (TSMC) is proposed at the special situation of medium frequency chopping. The validity of the proposed concept has been verified by simulation results and experiment waveforms from a scaled down laboratory prototype.

• Journal of Information Processing Systems
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• v.16 no.1
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• pp.120-131
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• 2020

In order to solve the problem of point clouds coordinate conversion of non-directional scanners, this paper proposes a basic Rodrigues rotation method. Specifically, we convert the 6 degree-of-freedom (6-DOF) rotation and translation matrix into the uniaxial rotation matrix, and establish the equation of objective vector conversion based on the basic Rodrigues rotation scheme. We demonstrate the applicability of the new method by using a bar-shaped emboss point clouds as experimental input, the three-axis error and three-term error as validate indicators. The results suggest that the new method does not need linearization and is suitable for optional rotation angle. Meanwhile, the new method achieves the seamless splicing of point clouds. Furthermore, the coordinate conversion scheme proposed in this paper performs superiority by comparing with the iterative closest point (ICP) conversion method. Therefore, the basic Rodrigues rotation method is not only regarded as a suitable tool to achieve the conversion of point clouds, but also provides certain reference and guidance for similar projects.

• Journal of Korea Multimedia Society
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• v.21 no.2
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• pp.130-137
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• 2018

Recently, human life is getting longer due to change of living environment and development of medical technology, and silver medical technology has been in the limelight. Geriatric skin disease is difficult to detect early, and when it is missed, it becomes a malignant disease and is difficult to treatment. Melanoma is one of the most common diseases of geriatric skin disease and initially has a similar modality with the nevus. In order to overcome this problem, we attempted to perform a feature analysis in order to attempt automatic detection of melanoma-like lesions. In this paper, one is first order analysis using information of pixels in radiomic feature. The other is a gray-level co-occurrence matrix and a gray level run length matrix, which are feature extraction methods for converting image information into a matrix. The features were extracted through these analyses. And classification is implemented by SVM.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.2
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• pp.46-52
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• 2012

This paper proposes a novel single-phase ac-ac converter topology based on the Z-source concept. The converter provides buck-boost function and plays the role of frequency changer. Compared to the traditional ac-dc-ac converter, it uses fewer devices, realizes direct ac-ac power conversion, and has a simpler circuit structure, so as to have higher efficiency and better circuit characteristics. Compared to the traditional matrix converter, it provides a wider voltage regulation range. The circuit topology, operating principle, control method and simulation results are given in this paper, and the rationality and feasibility is verified.

• Bulletin of the Korean Chemical Society
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• v.34 no.5
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• pp.1361-1365
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• 2013

The smallest ketenimine and hydrogen cyanide N-methylide ($CH_2CNH$ and $CH_2NCH$) are provided from the argon/acetonitrile matrix samples exposed to radiation from laser ablation of transition-metals. New infrared bands are observed in addition to better determination of the vibrational characteristics for the previously reported bands, and the $^{13}C$ substituted isotopomers ($^{13}{CH_2}^{13}CNH$ and $^{13}CH_2N^{13}CH$) are also generated. Density functional frequency calculations and the D and $^{13}C$ isotopic shifts substantiate the vibrational assignments. $CH_2CNH$ is probably produced through single-step conversion of $CH_3CN$, whereas $CH_2NCH$ through two-step conversion via 2H-azirine. Inter-conversions between these two products evidently do not occur during photolysis and annealing.

• Transactions of the Korean hydrogen and new energy society
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• v.32 no.6
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• pp.534-541
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• 2021

In this study, a novel microwave-matrix reformer was proposed to convert CH₄, which is a major component, to a high quality hydrogen energy. And to identify this performance, it was investigated for O₂/C ratio, steam feed amount and reformed gas recirculation which are affected for methane conversion and product gas yield. Through the parametric screening studies, optimal operating conditions were that O₂/C ratio, steam feed amount and recirculation rate were 1.1, 10 mL/min and 30 L/min. In this conditions, CH₄ conversion was 68.1%, H₂ selectivity 77.2 and H₂/CO ratio 2.62 which are possible applying SOFC stack for RPG (residential power generator).

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.77-86
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• 2002

Current composites are made with dimethacrylate monomers and silane-treated silica microfillers, either alone or with silane treated glass fillers The main reasons for clinical failure of dental composites are secondary caries, wear and fracture. Most of practitioner want to get a composite which is more tougher under occlusal stress, less polymerization contraction, and better handling properties in application clinically. The aim of this study was to investigate the influence of resin matrix with various flows on the physical proper-ties such as fracture toughness and degree of conversion of the experimental resins. It was hypothesized that flexible or tough resin composites can be designed by judicious choice of monomer composition Various flow resin matrices containing Bis-GMA, UDMA, and TEG-DMA were made by altering the pro-portion of the monomers. After the unfilled resins were light-cured for different light intensity, the fracture toughness(K$_{1c}$) was measured according to ASTM standard using the single edge notched geometry, and degree of conversion(DC) was measured by FTIR. And experimental composites were formulated with variations in the proportion of silanated quartz and strontium glass fillers as 60, 75, and 77wt%. Also, the physical properties of composites with various filer contents were evaluated as same manner. All resulting data were compared by ANOVA/Tukeys test at 0.05 level. The results were as follows; 1. The degree of conversion of high flow resin containing less Bis-GMA was higher than that of low flow unfilled resin 2. While the degree of conversion of unfilled resin was increased according to light intensity for polymerization, there was no significant increase with moderate and high light intensity. Also, the fracture toughness was not increased by high light intensity. 3. The fracture toughness was high in the low flow unfilled resin containing higher contents of Bis-GMA. 4. There was a significant increase for fracture toughness and a tendency for degree of conversion to be reduced when the content of fillers was increased. 5. In the experimental composites, the flow of resin matrix did not affected on the fracture toughness, even, which was decreased as increase of viscosity. These results showed that the physical properties of a dental composite could be attributed to the flow of resin matrix with relative content of monomers. Specific combination of resin monomers should be designed to fulfil the needs of specific indication for use.

• Transactions of the Korean hydrogen and new energy society
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• v.22 no.1
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• pp.100-108
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• 2011

The use of biogas as an energy source reduces the chance of possible emission of two greenhouse gases, $CH_4$ and $CO_2$, into the atmosphere at the same time. Its nature of being a reproducible energy source makes its use even more attractive. This research if for the hydrogen production through the steam reforming of the biogas. The biogas utilized 3D-IR matrix burner in which the surface combustion is applied. The nickel catalyst was used inside a reformer. Parametric screening studies were achieved as Steam/Carbon ratio, biogas component ratio, Space velocity and Reformer temperature. When the condition of Steam/Carbon ratio, $CH_4/CO_2$ ratio, Space velocity and Refomer temperature were 3.25, 60%:40%, 19.32L/$g{\cdot}hr$ and $700^{\circ}C$ respectively, the hydrogen concentration and methane conversion rate were showed maximum values. Under the condition mentioned above, $H_2$ concentration was 73.9% and methane conversion rate was 98.9%.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.321-324
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• 2002

For a rule-based conversion of Hangout into the Roman alphabet rather than a word-for-word conversion, one must come up with a faultless model for the Korean standard pronunciation rules, which are the basis of the Romanization. It is on this foundation that the Korean-Roman alphabet conversion table can be created. For linguistic modeling using PetriNet, modeling boundary and notation of modeling can be defined. In order to describe PetriNet, which is a dynamic modeling tool, as a static one, one can model the standard Korean pronunciation rules and the Hangout-Roman alphabet notation by conversion into incident matrix Thus, this research attempts to develop a mathematical modeling tool for a natural language using PetriNet, and create a Korean-Roman alphabet conversion table.