• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1627-1637
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• 2024

This research paper proposes a novel methodology for predicting the optimal location of friction supports to effectively mitigate vibrational energy in piping systems. The incorporation of friction forces in the dynamic characteristics of the system introduces inherent nonlinearity, making its analysis challenging. Typically, numerical solutions in the time domain are employed to circumvent the complexities associated with finding analytic solutions for nonlinear systems. However, time domain analysis (TDA) can be computationally intensive and demand significant computational resources due to the intricate calculations stemming from nonlinearity. To address this computational burden, this study presents an efficient approach based on linear analysis to predict the ideal position for installing friction supports as a replacement for fixed supports. Furthermore, we investigate the relationship between the installation positions of friction supports and their effectiveness in absorbing vibrations using the harmonic balanced method (HBM). Both methodologies are validated by comparing the obtained results with those obtained through time domain analysis (TDA) using the finite element method (FEM).

• Journal of the Korean Society of Industry Convergence
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• v.27 no.4_1
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• pp.735-740
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• 2024

Data released by the National Fire Agency showed that the total incidence of fires from 2014 to 2023 was 410,497, among which 75,215 were house fires, constituting 18% of the total occurrences. The fatalities resulting from house fires numbered 1,435. Fatalities stemming from prior house fires occurred between midnight and 6 am, coinciding with periods of sleep and diminished responsiveness to fire emergencies. A fire safety labeling system is proposed to prevent fire hazards associated with household products. This system primarily entails indicators of thermal energy and inherent fire attributed to household products. Furthermore, the Korea Fire Safety Institute has suggested adopting a risk label as a concrete measure plan for implementing the fire safety labeling system for household products. The results promise to safeguard the public against fires and increase the exports of household commodities by enhancing the corporate reputation through positive association with fire safety measures.

• ETRI Journal
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• v.46 no.4
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• pp.633-647
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• 2024

In e-commerce platforms, sentiment analysis on an enormous number of user reviews efficiently enhances user satisfaction. In this article, an automated product recommendation system is developed based on machine and deep-learning models. In the initial step, the text data are acquired from the Amazon Product Reviews dataset, which includes 60 000 customer reviews with 14 806 neutral reviews, 19 567 negative reviews, and 25 627 positive reviews. Further, the text data denoising is carried out using techniques such as stop word removal, stemming, segregation, lemmatization, and tokenization. Removing stop-words (duplicate and inconsistent text) and other denoising techniques improves the classification performance and decreases the training time of the model. Next, vectorization is accomplished utilizing the term frequency-inverse document frequency technique, which converts denoised text to numerical vectors for faster code execution. The obtained feature vectors are given to the modified convolutional neural network model for sentiment analysis on e-commerce platforms. The empirical result shows that the proposed model obtained a mean accuracy of 97.40% on the APR dataset.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.120-126
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• 2009

As the information age grows rapidly, the amount of digital texts has been increasing as well. It has brought an increasing of visualization case in order to figure out lots of digital texts. Existing visualized design of digital text is merely concentrating on figuration of subject word through adoption of stemming algorithm and word frequency extraction, prominence of meaning of text, and connection in between sentences. So it is a fact that expression of rhythm that can visualize sentimental feeing of digital text was insufficient. Syllable is a phoneme unit that can express rhythm more efficiently. In sentences, syllable is a most basic pronunciation unit in pronouncing word, phase and sentence. On this basis, accent, intonation, length of rhythm factor and others are based on syllable. Sonority, which is most closely associated with definitions of syllable, is expressed through air flow of igniting lung and acoustic energy that is specified kinetic energy into sonority. Seen from this perspective, this study examines phonologic definition and characteristics based on syllable, which is properties of digital text, and research the way to visualize rhythm through diagram. After converting digital text into phonetic symbol by the experiment, rhythm information are visualized into images using degree of resonance, which was started from rhythm in all languages, and using syllable establishment of digital text. By visualizing syllable information, it provides syllable information of digital text and express sentiment of digital text through diagram to assist user's understanding by systematic formula. Therefore, this study is aimed at planning for easy understanding of text's rhythm and realizing visualization of digital text.

• Journal of the Korean School Mathematics Society
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• v.11 no.4
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• pp.655-676
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• 2008

This paper analyzed contents related to statistics in the 7th elementary mathematics curriculum in conjunction with main changes in the recent revised curriculum. This paper then provided detailed analyses of textbooks and workbooks in terms of main contents, instructional methods of graphs, and comprehension of graphs required to students in order to look closely at how such instructional materials would put the vision of the curriculum into action. It is expected that the issues and suggestions stemming from this analysis are informative in constructing new textbooks and workbooks.

• Korean Journal of Remote Sensing
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• v.30 no.3
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• pp.399-415
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• 2014

The intensity of stormwater runoff is particularly acute across cities located in arid climates. During flash floods loose sediment and pollutants are typically transported across sun-hardened surfaces contributing to widespread degradation of water quality. Rapid, dense urbanization exacerbates the problem by creating continuous areas of impervious surfaces, perforated only by a few green patches. Our work demonstrates how the latest techniques in remote sensing can be used to routinely measure urban land cover types, impervious cover, and vegetated areas. In addition, multiple regression models can then infer relationships between urban land use and land cover types with stormwater quality data, initially sampled at discrete monitoring sites, and then extrapolated annually across an arid city; in our case, the city of Phoenix in Arizona, USA. Results reveal that from 30 storm event samples, solids and heavy metal pollutants were found to be highly related with general impervious surfaces; in particular, with industrial and commercial land use types. Repercussions stemming from this work include support for public policies that advocate environmental sustainability and the more recent focus on urban livability. Also, advocacy for new urban construction and re-development that both steer away from vast unbroken impervious surfaces, in place of more fragmented landscapes that harmonize built and green spaces.

• Journal of the Ergonomics Society of Korea
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• v.36 no.5
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• pp.373-383
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• 2017

Objective: The aim of this study is to introduce an operator console design review system suitable for designing and evaluating consoles based on human factor guidelines for a digitalized main control room in an advanced nuclear power plant which has a requirement for anthropometric data usage. Background: The system interface of the main control room in a nuclear power plant has been getting digitalized and consists of various consoles with many information displays. Console operators often face human-computer interactive problems due to inappropriate console design stemming from the perceptual constraints of anthropometric data usage. Method: Computational models with a process of visual perception and variables of anthropometric data are used for designing and evaluating operator consoles suitable for human system interface guidelines, which are used in an advanced nuclear power plant. Results: From the computational model and simulation application, console dimensions and a designing test module, which would be used for designing suitable consoles with safety concerns in a nuclear power plant, have been introduced. Conclusion: This case study may influence employing a suitable design concept with various anthropometric data in many areas with safety concerns and may show a feasible solution to designing and evaluating the safety console dimensions. Application: The results of this study may be used for designing a control room with the human factors requiring a safe working environment.

• Computers and Concrete
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• v.15 no.6
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• pp.903-919
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• 2015

The flow of freshly mixed cement-based material shows thixotropy, which implies some difficulties on robust measurement of its rheological properties: The flow curve of thixotropic materials depends on the used protocol. For examples, higher viscosity is obtained when the rate of shear strain is more quickly increased. Even though precise measurement and modelling of the concrete rheology needs to consider the thixotropic effect, engineers in the concrete field prefer considering as a non-thixotropic Herschel-Bulkley fluid, even more simply Bingham fluid. That is due to robustness of the measurement and application in casting process. In the aspect of simplification, this papers attempts to mimic the thixoropic flow by the non-thixotropic Herschel-Bulkley model. Disregarding the thixotropy of cement based materials allows us to adopt the rheological concept in the field. An optimized protocol to measure the Bingham parameters was finally found based on the accuracy and reproducibility test of cement paste samples, which minimizes the error of simulation stemming from the assumption of non-thixotropy.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.75-75
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• 2015

Strong interactions between electromagnetic radiation and electrons at metallic interfaces or in metallic nanostructures lead to resonant oscillations called surface plasmon resonance with fascinating properties: light confinement in subwavelength dimensions and enhancement of optical near fields, just to name a few [1,2]. By utilizing the properties enabled by geometry dependent localization of surface plasmons, metal photonics or plasmonics offers a promise of enabling novel photonic components and systems for integrated photonics or sensing applications [3-5]. The versatility of the nanoplasmonic platform is described in this talk on three folds: our findings on an enhanced ultracompact photodetector based on nanoridge plasmonics for photonic integrated circuit applications [3], a colorimetric sensing of miRNA based on a nanoplasmonic core-satellite assembly for label-free and on-chip sensing applications [4], and a controlled fabrication of plasmonic nanostructures on a flexible substrate based on a transfer printing process for ultra-sensitive and noise free flexible bio-sensing applications [5]. For integrated photonics, nanoplasmonics offers interesting opportunities providing the material and dimensional compatibility with ultra-small silicon electronics and the integrative functionality using hybrid photonic and electronic nanostructures. For sensing applications, remarkable changes in scattering colors stemming from a plasmonic coupling effect of gold nanoplasmonic particles have been utilized to demonstrate a detection of microRNAs at the femtomolar level with selectivity. As top-down or bottom-up fabrication of such nanoscale structures is limited to more conventional substrates, we have approached the controlled fabrication of highly ordered nanostructures using a transfer printing of pre-functionalized nanodisks on flexible substrates for more enabling applications of nanoplasmonics.

• Journal of the Korean School Mathematics Society
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• v.13 no.1
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• pp.1-21
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• 2010

This paper analyzed the contents and instructional methods of various plane figures presented mainly in a series of elementary mathematics textbooks on the basis of the analysis of related contents in the 2007 revised national mathematics curriculum. As such, this paper provided detailed analyses of how textbooks would implement the vision and intention of the curriculum, how the definition of each plane figure in the textbooks might be different from its mathematical definition, and how textbooks would introduce each plane figure. It is expected that the issues and suggestions stemming from this analysis will be informative in designing new instructional materials.