• The Korean Journal of Applied Statistics
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• v.16 no.2
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• pp.321-333
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• 2003

Self-organizing map (SOM), a unsupervised learning neural network, has been developed by T. Kohonen since 1980's. Main application areas were pattern recognition and text retrieval. Because of that, it has not been spread to statisticians until late. Recently, SOM's are frequently drawn in data mining fields. Kohonen's SOM, however, needs improvements to become a statistician's standard tool. First, there should be a good guideline as for the size of map. Second, an enhanced visualization mode is wanted. In this study, principal components self-organizing map (PC-SOM), a modification of Kohonen's SOM, is proposed to meet such needs. PC-SOM performs one-dimensional SOM during the first stage to decompose input units into node weights and residuals. At the second stage, another one-dimensional SOM is applied to the residuals of the first stage. Finally, by putting together two stages, one obtains two-dimensional SOM. Such procedure can be easily expanded to construct three or more dimensional maps. The number of grid lines along the second axis is determined automatically, once that of the first axis is given by the data analyst. Furthermore, PC-SOM provides easily interpretable map axes. Such merits of PC-SOM are demonstrated with well-known Fisher's iris data and a simulated data set.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.378-381
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• 2002

In this paper, we proposed an electromyography(EMG) based control method of a virtual robot arm as an adaptive human supporting system or remote control system, which consists of an shoulder control part, elbow control part, and wrist control part. The system uses four surface electrodes to acquire the EMG signal from operator. It is shown from the experiments that the EMG patterns during arm motions can be classified sufficiently by using SOM and LVQ. The interface system based on PC environment is constructed to 3-D graphic user interface(GUI) program. Experimental results show that proposed method obtains approximately 94 percent of success in classification.

• Journal of Forest and Environmental Science
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• v.39 no.2
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• pp.73-80
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• 2023

Little is known of the life history of Garcinia kola; the objective of this study, therefore, was to assess the fruiting age and tree size of the species in a coastal humid tropical climate plantation condition. A total 103 trees were used in the study viz; 80 ten-year-old trees at reproductive maturity onset and 13 thirty-year-old trees with several cycles of reproduction that constitute two independent variables. Data collected were age of onset of flowering and size at reproductive maturity onset. Relative size at reproductive maturity onset (RSOM) was estimated as size at reproductive maturity onset (SOM) divided by asymptotic maximal size (AMS). Data analysis was conducted using pairwise t-test and principal component analysis (PCA). Reproductive maturity onset (flowering) was recorded in the ten-year-old stand eight (8) years after planting. Mean size at reproductive maturity onset (SOM) was height 5.32±1.7 m, dbh 0.11±0.03 m, total number of branches was 29.6±7.3, crown depth 5.24±1.05 m, crown diameter was 4.78±0.7 m, branch diameter 0.098±0.01 m, leaf length 0.13±0.02 m, leaf breadth 0.37±0.01 m, twig length 0.35±0.11 m and leaf per twig 6±0.84 and asymptotic maximal size (AMS) was height 19.85±0.76 m, dbh 0.95±0.09 m, total number of branches 62±5, crown depth 18.83±0.7 m, crown diameter 12.5±1.64 m, branch diameter 0.5±1.6 m, leaf length 0.16±0.023 m, leaf breadth 0.45±0.12 m, twig length 0.37±0.11 m and leaf per twig 19±7.5. Pairwise t-test analysis showed there was significant differences between SOM and AMS in all growth factors except leaf length, leaf breadth, and twig length. Highest relative size at reproductive maturity onset (RSOM) was recorded in leaf length 0.82, twig length 0.82, and leaf breadth 0.80, while, the lowest was branch diameter 0.11. Four components out of the total of eleven were extracted to explain the relationship in RSOM: Principal component one (PC1) explained 37.23%; PC2 26.4%, PC3 22.73%, and PC4 13.64%.

• Proceedings of the Korea Contents Association Conference
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• 2013.05a
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• pp.253-254
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• 2013

In the preceding studies, an analysis of Saga Prefectural sightseeing information by a self-organizing map (SOM) has been tried. And recent development on information and communication technology (ICT) will help us to access any results via the mobile devices easily. Then, in order to realize this basic idea, development of an application for mobile devices is investigated through some preliminary computer simulations on the standard desktop PC in this article.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.252-252
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• 2012

It is widely accepted that short exciton diffusion lengths of organic semiconductors with respect to the film thickness limit the charge (hole and electron) separation before excitons recombination in organic photovoltaic (OPV) cells. Therefore the efficient absorption of incident light within the thin active organic layer is of great importance to improve the power conversion efficiency (PCE) of the cells. In this work, we fabricated 2-dimensionally (2D) nano-patterned poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOST:PSS) layers using capillary phenomenon and nano-imprinting technology at the scale of several hundred nanometers. This 2D nano-patterned PEDOT:PSS layer exerted photonic crystal effect such as redirection of light paths and variation of light intensity at specified wavelengths. It is also expected that the consequently alternated light pass lengths and intensities change the absorption properties of zinc phthalocyanine (ZnPc) thin films grown on top of the nano-patterned PEDOT:PSS layer. The influence of conductivity and thickness of the PEDOT:PSS layer on the absorption properties of ZnPc thin films were also investigated.

• International Journal of Contents
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• v.9 no.3
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• pp.15-18
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• 2013

In the preceding studies, an analysis of Saga Prefectural sightseeing information by a Self-Organizing Map (SOM) has been tried. And recent development on Information and Communication Technology (ICT) will help us to access any results via the mobile devices easily. This is why the mobile devices, e.g., smartphones and tablet computers, have an operating system installed, and we can improve their functions by downloading any applications on the Web. Then, in order to realize this basic idea, development of an application for the mobile devices is investigated through some computer simulations on the standard desktop PC in this paper. As a result, it is found that i) a developed feature map is useful to identify some candidate topics, ii) a touchscreen is suitable to show the feature map, and iii) arrangement of the feature map can be modified based on our interests. Then, it is concluded that the proposed idea seems to be applicable, even though further consideration is required to brush it up.

• Korean Journal of Plant Resources
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• v.33 no.6
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• pp.551-557
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• 2020

In this study, we were performed to elucidate the antioxidant and anticancer activity by leaves extracts from Acer tegmentosum (AT-L). In DPPH, ABTS radical scavenging activity, the AT-L revealed the high scavenging activity. Especially, the AT-L measured the highest ABTS radical scavenging activity, which is higher than ascorbic acid. The types of human cancer cells for evaluating the anticancer activity were colorectal cancer (SW480), prostate cancer (PC-3), breast cancer (MCF-7), pancreatic cancer (AsPC-1), lung cancer (A549) and liver cancer (HepG2). Human cancer cell viability was measured using MTT assay. Treatment of the AT-L decreased the cell viability and induced apoptosis in SW480 cells. These results suggest that extracts of the AT-L can be used as supplementary material for developing the natural antioxidant and anticancer drug for human cancer cells.

• Journal of Plant Biotechnology
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• v.48 no.2
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• pp.106-114
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• 2021

We evaluated the anti-cancer activity against human prostate cancer cells and the associated molecular mechanism of extracts from the branches of Rhamnus yoshinoi (RYB). Treatment with RYB suppressed viability of human prostate cancer cells (PC-3) and decreased protein levels of both β-catenin and T-cell factor 4 (TCF4). This was reflected in reduced TCF4 mRNA, but not decreased β-catenin mRNA. PC-3 cells were pretreated with the proteosome inhibitor MG132 before treatment with RYB, which blocked RYB-mediated down regulation of β-catenin in PC-3 cells, thus confirming that RYB promotes the proteasomal degradation of β-catenin. RYB induced β-catenin phosphorylation, and GSK-3β inhibition by LiCl blocked the phosphorylation and proteasomal degradation of β-catenin by RYB. These results suggest that GSK-3β may be an important upstream kinase for RYB-mediated regulation of β-catenin. Finally, GC/MS analysis of RYB identified 18 compounds. Based on these findings, RYB shows potential for development as a therapeutic agent for prostate cancer.