• Journal of the Society of Naval Architects of Korea
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• v.56 no.6
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• pp.507-514
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• 2019

Computational studies of accelerating flow around 2D Circular Cylinder was performed to investigate characteristics of wake field and drag forces. Previous studies had revealed that drag on the cylindrical body in accelerating flow is much greater than that in the flow with constant velocity; however, the underlying physics on the drag increase has not been clearly investigated. In order to investigate the drag increase and its relationship with wake development, this study employed a finite-volume based CFD code, Fluent 13.0 with k-ω SST model for turbulence effects. Inflows are modeled with varied accelerations from 0.4905 to 9.81m/s². The drag computed in the present study is in good agreement with previous studies, and clearly shows the increase compared to the drag on the body in the flow with constant velocity. The results also show that drag crisis observed at high Reynolds number in the case of the flow with constant velocity is also found in the case of accelerating flow. The analysis for wake and recirculation length shows that conventional vortex shedding does not occur even at high Reynolds number and the drag increase is larger at higher acceleration.

• Journal of Broadcast Engineering
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• v.21 no.3
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• pp.357-368
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• 2016

In DAB+, HE-AAC v2 codec is applied for the fixed rate transmission of audio stream. In case that xHE-AAC codec including USAC, a more efficiency is expected when the variable frame is used in a given same bandwidth compared to the fixed frame transmission. For this to be realized, audio streams need to be multiplexed in a sub-channel before transmission, then a method is required to identify the border of each audio frames. In this paper, the toggled sync byte and additional identification field being sequentially placed between AU borders are proposed in order to deal with the AU border identification. In addition, the Reed-Solomon based error correction code which is compliant to DAB+ is proposed.

• Journal of dental hygiene science
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• v.20 no.2
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• pp.107-117
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• 2020

Background: In this study, we tried to comprehensively explore clinical dental hygienist's experience of a prevention-based incremental oral health care program, which was pilot-operated by dental clinics, define prevention-based incremental oral health care as experienced in the field, and identify factors to be considered. Methods: This study conducted a focus group interview with five dental hygienists who participated in an ongoing oral management pilot project in 2016. The interview was conducted by a researcher, and the co-research team attended as progress assistants and recorded characteristics of the participants, main dictations, and non-verbal characteristics. All interviews were recorded and underwent thematic analysis to examine the questions of the study as the main axis. Results: As a result of the study, 65 meaningful statements were extracted by code, integrated into 24 sub-categories, and structured into 11 categories. Finally, four keywords were drawn: characteristics, facilitating factors, conflicting factors, and improvement measures for prevention-based incremental oral health care. Regarding prevention-based incremental oral health care in dental clinics, dental hygienists were highly aware of the physical and mental burdens of personalized treatment and education for each individual. They were responsible for the patient and for facilitating changes in the behavior of the client, leading to professional satisfaction. The dental team's cooperation and supportive attitude were found essential to continue oral health care in the dental clinic. Conclusion: Through dental team-based treatment philosophy sharing and collaboration, it is possible to provide prevention-based incremental oral health care in dental clinics. In future, it is necessary to develop a system for establishing a sustainable preventative management system for public health promotion.

• Fire Science and Engineering
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• v.30 no.6
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• pp.118-123
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• 2016

In the event of a building fire, it is important to control the smoke generated to ensure the safe evacuation of occupants. A natural smoke ventilator should be installed to exhaust the fire smoke in accordance with the Korean building Act and Code. On the other hand, the present law does not specify the contents regarding natural smoke ventilators sufficiently. The problems that occur in various parts, such as the installation target, installation location, free area, and the control and maintenance of natural smoke ventilators need to be solved. In this study, the problem of the current system was examined through domestic and foreign standards, preliminary research, and field investigations. In addition, suggestions for improvement are provided.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.1
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• pp.29-41
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• 2008

The present paper provides a CFD analysis of diffraction problem for a ship with forward speed using an unsteady RANS simulation method, a WAVIS code. The WAVIS viscous solver adopting a finite volume method has second order accuracy in time and field discretizaions for the RANS equations. A two phase level-set method and a realizable ${\kappa}-{\varepsilon}$ turbulence model are adopted to compute the free surface and to meet the turbulence closure, respectively. To validate the capability of the present numerical methods for the simulation of an unsteady progressive regular wave, computations are performed for three grid sets with refinement ratio of ${\sqrt{2}}$. The main simulation is performed for a DTMB5512 model with a forward speed in a regular head sea condition. Validation of the present numerical method is carried out by comparing the present CFD results with available unsteady experimental data published in the 2005 Tokyo CFD Workshop: resistance, heave force, pitch moment, unsteady free surface elevations and velocity fields.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.331-333
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• 2015

Gravitational interactions - mergers and fly-by encounters - between galaxies play a key role as the drivers of their evolution. Here we perform a cosmological N-body simulation using the tree-particle-mesh code GOTPM, and attempt to separate out the effects of mergers and fly-bys between dark matter halos. Once close pair halos are identified by the halo finding algorithm PSB, they are classified into mergers ($E_{12}$ < 0) and fly-by encounters ($E_{12}$ > 0) based on the total energy ($E_{12}$) between two halos. The fly-by and merger fractions as functions of redshift, halo masses, and ambient environments are calculated and the result shows the following.(1) Among Milky-way sized halos ($0.33-2.0{\times}10^{12}h^{-1}M{\odot}$), $5.37{\pm}0.03%$ have experienced major fly-bys and $7.98{\pm}0.04%$ have undergone major mergers since z ~ 1; (2) Among dwarf halos ($0.1-0.33{\times}10^{12}h^{-1}M{\odot}$), $6.42{\pm}0.02%$ went through major fly-bys and $9.51{\pm}0.03%$ experienced major mergers since z ~ 1; (3) Milky-way sized halos in the cluster environment experienced fly-bys (mergers) 4-11(1.5-1.7) times more frequently than those in the field since z ~ 1; and (4) Approaching z = 0, the fly-by fraction decreases sharply with the merger fraction remaining constant, implying that the empirical pair/merger fractions (that decrease from z ~ 1) are in fact driven by the fly-bys, not by the mergers themselves.

• Nuclear Engineering and Technology
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• v.36 no.2
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• pp.196-202
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• 2004

KAERI (Korea Atomic Energy Research Institute) is at present preparing a preliminary performance assessment to set up the HLW disposal concept of Korea. The solubility of the radionuclides contained in HLW is necessary as a source term in order to predict their potential migration in both the near and far fields. The solubility of actinides (Th, Am, U, Np and Pu) for a reference deep groundwater of Korea has been calculated using a geochemical code with thermodynamic data selected by a peer review of existing thermodynamic databases and literature. The solubilities from the experimental study and/or field observations from natural analogue studies are compared. The sensitivity of solubility to the variability of three main parameters of groundwater (pH, Eh, and carbonate concentration) is also investigated. The results of the sensitivity analysis show that the solubility of actinides strongly depends on the parameters considered. Within the range of parameter values studied (pH=7 to 10, Eh=-0.4 to -0.1V, and carbonate concentration=1.E-5 to 1.E-2 mol/L), the solubility of each actinide exists between 1.4E-10 and 1.6E-6 mol/L for Am, 4.9E-9 and 2.8E-6 mol/L for Th, 3.2E-9 and 5.7E-4 mol/L for U, 1.1E-9 and 1.0E-7 mol/L for Np, and 4.0E-11 and 2.8E-6 mol/L for Pu, respectively.

• The Korea Journal of Herbology
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• v.31 no.6
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• pp.53-61
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• 2016

Objectives : The study was aimed to analyze the correlation between Herbology and contemporary research results, KCD-codes, and terms. The study will present information that can be used to find the direction of further researches and be applied to the education of Herbology. Methods : Papers were searched in PubMed, ScienceDirect, and KISS. Papers were then categorized as "medicine and pharmacy articles" or "articles unrelated to medicine and pharmacy." Medicine or pharmacy articles about Clerodendri Trichotomi Folium were matched with treatments in Herbology and KCD-codes. Medicine and pharmacy articles not researching Clerodendri Trichotomi Folium mainly, and articles unrelated to medicine and pharmacy were categorized and analyzed. KCD-codes and terms were arranged by treatments in Herbology. Research types, the number of papers, and the citation count were arranged by each treatment in Herbology. Degrees of Herbology research were represented as a number and a graph. Results : There were 25 Medicine and pharmacy articles about Clerodendri Trichotomi Folium, 6 medicine and pharmacy articles which did not studied Clerodendri Trichotomi Folium mainly. Among in vivo researched herbology treatments, Hypertension scored 47, migraine scored 47, and abscess and scabies scored 53. Conclusions : The category 'Abscess and scabies' was the most researched treatment in Herbology. Of the medicine and pharmacy articles that did not match treatments in Herbology, there were in vivo researching on reflux oesophagitis, Malignant neoplasm of bronchus and lung, and that of breast which can be used in the Herbology education field.

• The KIPS Transactions:PartD
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• v.15D no.6
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• pp.861-872
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• 2008

As rapid development of computing environment, field of automatic identification research which interoperates with various physical objects and digital information is making active progress. Although the automatic identification system is widely used in various industries, application of automatic identification system in the field of medical health doesn't reach other industry. Therefore research in medical health supplies such as medical equipment, blood, human tissues and etc is on progress. This paper suggests the application of automatic identification technology for biological resources which is core research material in human genome research. First of all, user environment requirements for the introduction of automatic identification technology are defined and through the experiments and research, barcode is selected as a suitable tag interface. Data Matrix which is 2D barcode symbology is chosen and data schema is designed based on UCC/EAN-128 for international defecto standard. To showapplicability of proposed method when applied to actual environment, we developed, tested and evaluated application as following methods. Experiments of barcode read time at 196 and 75 below zero which is actual temperature where biological resources are preserved resulted read speed of average of 1.6 second and the data schema satisfies requirements for the biological resources application. Therefore suggested method can provide data reliability as well as rapid input of data in biological resources information processing.

• Knowledge Management Research
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• v.25 no.2
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• pp.19-47
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• 2024

Organizational ability to analyze and utilize data plays an important role in knowledge management and decision-making. This study aims to investigate the potential application of large language models in corporate data analysis. Focusing on the field of human resources, the research examines the data analysis capabilities of these models. Using the widely studied IBM HR dataset, the study reproduces machine learning-based employee turnover prediction analyses from previous research through ChatGPT and compares its predictive performance. Unlike past research methods that required advanced programming skills, ChatGPT-based machine learning data analysis, conducted through the analyst's natural language requests, offers the advantages of being much easier and faster. Moreover, its prediction accuracy was found to be competitive compared to previous studies. This suggests that large language models could serve as effective and practical alternatives in the field of corporate data analysis, which has traditionally demanded advanced programming capabilities. Furthermore, this approach is expected to contribute to the popularization of data analysis and the spread of data-driven decision-making (DDDM). The prompts used during the data analysis process and the program code generated by ChatGPT are also included in the appendix for verification, providing a foundation for future data analysis research using large language models.