• Proceedings of the Korea Concrete Institute Conference
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• 1998.10b
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• pp.773-778
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• 1998

For imaging of concrete specimens using radar, the principles of radar, microwave, and the electromagnetic properties of concrete are discussed. Experimental data obtained from radar measurement of concrete specimens with no steel bars at three different frequency bandwidths of 2~3.4 GHz, 3.4~5.8 GHz and 8~12 GHz are processed to determine the thickness of the specimens. A signal processing scheme has been implemented to visualize the concrete specimens. The purpose of this study is to determine particular frequency range appropriate for measuring the thickness of concrete specimens using radar.

• Journal of Intelligence and Information Systems
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• v.28 no.1
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• pp.131-154
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• 2022

Recently, researches on unstructured data analysis have been actively conducted with the development of information and communication technology. In particular, topic modeling is a representative technique for discovering core topics from massive text data. In the early stages of topic modeling, most studies focused only on topic discovery. As the topic modeling field matured, studies on the change of the topic according to the change of time began to be carried out. Accordingly, interest in dynamic topic modeling that handle changes in keywords constituting the topic is also increasing. Dynamic topic modeling identifies major topics from the data of the initial period and manages the change and flow of topics in a way that utilizes topic information of the previous period to derive further topics in subsequent periods. However, it is very difficult to understand and interpret the results of dynamic topic modeling. The results of traditional dynamic topic modeling simply reveal changes in keywords and their rankings. However, this information is insufficient to represent how the meaning of the topic has changed. Therefore, in this study, we propose a method to visualize topics by period by reflecting the meaning of keywords in each topic. In addition, we propose a method that can intuitively interpret changes in topics and relationships between or among topics. The detailed method of visualizing topics by period is as follows. In the first step, dynamic topic modeling is implemented to derive the top keywords of each period and their weight from text data. In the second step, we derive vectors of top keywords of each topic from the pre-trained word embedding model. Then, we perform dimension reduction for the extracted vectors. Then, we formulate a semantic vector of each topic by calculating weight sum of keywords in each vector using topic weight of each keyword. In the third step, we visualize the semantic vector of each topic using matplotlib, and analyze the relationship between or among the topics based on the visualized result. The change of topic can be interpreted in the following manners. From the result of dynamic topic modeling, we identify rising top 5 keywords and descending top 5 keywords for each period to show the change of the topic. Existing many topic visualization studies usually visualize keywords of each topic, but our approach proposed in this study differs from previous studies in that it attempts to visualize each topic itself. To evaluate the practical applicability of the proposed methodology, we performed an experiment on 1,847 abstracts of artificial intelligence-related papers. The experiment was performed by dividing abstracts of artificial intelligence-related papers into three periods (2016-2017, 2018-2019, 2020-2021). We selected seven topics based on the consistency score, and utilized the pre-trained word embedding model of Word2vec trained with 'Wikipedia', an Internet encyclopedia. Based on the proposed methodology, we generated a semantic vector for each topic. Through this, by reflecting the meaning of keywords, we visualized and interpreted the themes by period. Through these experiments, we confirmed that the rising and descending of the topic weight of a keyword can be usefully used to interpret the semantic change of the corresponding topic and to grasp the relationship among topics. In this study, to overcome the limitations of dynamic topic modeling results, we used word embedding and dimension reduction techniques to visualize topics by era. The results of this study are meaningful in that they broadened the scope of topic understanding through the visualization of dynamic topic modeling results. In addition, the academic contribution can be acknowledged in that it laid the foundation for follow-up studies using various word embeddings and dimensionality reduction techniques to improve the performance of the proposed methodology.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.12
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• pp.1017-1026
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• 2016

The present paper describes the two off-surface visualization techniques and their application examples to vortex flows. One of the two visualization techniques is the classical smoke-wire technique, and the other is the visualization technique using the micro water-droplets generated by the home-style ultrasonic humidifier. The smoke-wire technique has the limit of air flow speed (about 5 m/sec for 0.07 mm-diameter wire) and the pollution problem, but it produces very fine and clear streak line sheet. It is applied to visualize the wing-tip vortices of a 3-dimensional wing. The micro water-droplet technique has the larger limit of air flow speed (above 10 m/sec) and is free from pollution and toxic problems compared to the smoke-wire technique. It is successfully applied to visualize the complex vortex system of a double-delta wing with an apex strake.

• Clinical and Experimental Reproductive Medicine
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• v.31 no.1
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• pp.75-81
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• 2004

Objective: The purpose of this study was to evaluate the efficacy and effect of various cryopreservation method on the survival and the cytoskeletal stability of metaphase II mouse oocyte. Methods: Mouse ovulated oocytes were collected and cryopreserved by a modified slow-freezing method with 1.5 M 1, 2-propanediol (PrOH)+0.1 M sucrose or by vitrification using cryo loop and EM grid with 40% ethylene glycol+0.6 M sucrose. Four hours after thawing, intact oocytes were fixed and stained with fluorescein isothiocyanate (FITC)-conjugated monoclonal anti-$\beta$-tubulin antibody to visualize spindle and propidium iodide (PI) to visualize chromosome. Spindle morphology was classified as follows: normal (barrel-shaped), slightly and absolute abnormal (multipolar or absent). Results: Survival rate of the frozen-thawed oocytes in vitrification group was significantly higher than that of slow-freezing group (62.7% vs. 24.4%, p<0.01). Vitrification with cryo loop showed significantly higher survival rate than that with EM grid (67.7% vs. 53.5%, p<0.05). On the other hand, proportion of normal spindle and chromosome configurations of the frozen-thawed oocytes between two vitrification group was not significantly different. Conclusion: For mouse ovulated oocytes, vitrification with cryo loop may be a preferable procedure compared to slow-freezing method. Further study should be needed to investigate developmental competency of frozen-thawed mouse oocytes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.1
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• pp.43-51
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• 2011

Natural convection heat transfer phenomena on a horizontal cylinder have been studied experimentally in order to investigate the applicability of analogy experimental methodology using a copper electroplating system and to visualize the local heat transfer rates depending on the angular position and the diameter of the horizontal cylinder. In the copper electroplating system, the copper ion produced at the anode moves by convection and diffusion to the cathode and reduces at the cathode, representing the heat transfer. By using aluminum cathode with a distinguishable color, the amount of copper plated could visualize the amount of heat transferred depending on the angular position of the cylinder. The diameter of the cylinder is varied from 0.01m to 0.15m, which correspond to Rayleigh numbers in the range of $1.73{\times}10^7$ to $5.69{\times}10^{11}$. The test results are in good agreement with existing heat transfer correlations.

• The Journal of the Korea Contents Association
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• v.7 no.5
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• pp.16-26
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• 2007

Because it is difficult on existing document retrieval systems to visualize the search result, search results show document titles and short summaries of the parts that include the search keywords. If the result list is long, it is difficult to examine all the documents at once and to find a relation among them. This study uses clustering to classify similar documents into groups to make it easy to grasp the relations among the searched documents. Also, this study proposes a two-level visualization algorithm such that, first, the center of clusters is projected to low-dimensional space by using multi-dimensional scaling to help searchers grasp the relation among clusters at a glance, and second, individual documents are drawn in low-dimensional space based on the center of clusters using the orbital model as a basis to easily confirm similarities among individual documents. This study is tested on the benchmark data and the real data, and it shows that it is possible to visualize search results in real time.

• Wind and Structures
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• v.5 no.6
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• pp.515-526
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• 2002

The wind flow over two-dimensional sinusoidal hilly obstacles with slope (the ratio of height to half width) of 0.5 has been investigated experimentally and numerically. Experiments for single and double sinusoidal hill models were carried out in a subsonic wind tunnel. The mean velocity profiles, turbulence statistics, and surface pressure distributions were measured at the Reynolds number based on the obstacle height(h=40 mm) of $2.6{\times}10^4$. The reattachment points behind the obstacles were determined using the oil-ink dot and tuft methods. The smoke-wire method was employed to visualize the flow structure qualitatively. The finite-volume-method and the SIMPLE-C algorithm with an orthogonal body-fitted grid were used for numerical simulation. Comparison of mean velocity profiles between the experiments and the numerical simulation shows a good agreement except for the separation region, however, the surface pressure data show almost similar distributions.

• Journal of Korea Multimedia Society
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• v.22 no.10
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• pp.1208-1214
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• 2019

4th industrial age! 5G-based video content has changed rapidly. How do you view and understand VR/AR/MR/holograms in the age of convergent technology media represented by digital convergence in the 21st century beyond the modern visual system of Descartes? It predicts extension to an interactive visual system. This study proposes a methodology to visualize the Lacanian visual acuity after applying it to the L-System and to understand the visual system of the 21st century.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.722-729
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• 2010

Prediction problems are widely used in medical domains. For example, computer aided diagnosis or prognosis is a key component in a CDSS (Clinical Decision Support System). SVMs with nonlinear kernels like RBF kernels, have shown superior accuracy in prediction problems. However, they are not preferred by physicians for medical prediction problems because nonlinear SVMs are difficult to visualize, thus it is hard to provide intuitive interpretation of prediction results to physicians. Nomogram was proposed to visualize SVM classification models. However, it cannot visualize nonlinear SVM models. Localized Radial Basis Function (LRBF) was proposed which shows comparable accuracy as the RBF kernel while the LRBF kernel is easier to interpret since it can be linearly decomposed. This paper presents a new tool named VRIFA, which integrates the nomogram and LRBF kernel to provide users with an interactive visualization of nonlinear SVM models, VRIFA visualizes the internal structure of nonlinear SVM models showing the effect of each feature, the magnitude of the effect, and the change at the prediction output. VRIFA also performs nomogram-based feature selection while training a model in order to remove noise or redundant features and improve the prediction accuracy. The area under the ROC curve (AUC) can be used to evaluate the prediction result when the data set is highly imbalanced. The tool can be used by biomedical researchers for computer-aided diagnosis and risk factor analysis for diseases.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.5
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• pp.9-19
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• 2011

In many instances a concise form of logic is often required for building today's complex systems. The method described in this paper can be used for a wide range of industrial applications that requires Boolean type of logic minimization. Unlike some of the previous logic minimization methods, the proposed method can be used to better gain insights into the logic minimization process. Based on the decimal valued matrix, the method described here can be used to find an exact minimized solution for a given Boolean function. It is a visual based method that primarily relies on grouping the cell values within the matrix. At the same time, the method is systematic to the extent that it can also be computerized. Constructing the matrix to visualize a logic minimization problem should be relatively easy for the most part, particularly if the computer-generated graphs are accompanied.