• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.3
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• pp.333-347
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• 2013

The present study numerically models the interaction between a regular wave and the roll motion of a rectangular floating structure. In order to simulate two-dimensional incompressible viscous two-phase flow in a numerical wave tank with the rectangular floating structure, the present study used the volume of fluid method based on the finite volume method. The sliding mesh technique is adopted to handle the motion of the rectangular floating structure induced by fluid-structure interaction. The effect of the wave period on the flow, roll motion and forces acting on the structure is examined by considering three different wave periods. The time variations of the wave height and the roll motion of the rectangular structure are in good agreement with experimental results for all wave periods. The present response amplitude operator is in good agreement with experimental results with the linear potential theory. The present numerical results effectively represent the entire process of vortex generation and evolution described by the experimental results. The longer wave period showed a different mechanism of the vortex evolution near each bottom corner of the structure compared to cases of shorter wave periods. In addition, the x-directional and z-directional forces acting on the structure are analyzed.

• Journal of Powder Materials
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• v.17 no.6
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• pp.456-463
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• 2010

This paper describes the results of the application of Cr-Diamond-like carbon (DLC) films for efficiency improvement through surface modification of spur gear parts in the hydraulic gear pump. Cr-DLC films were successfully deposited on SCM 415 substrates by a hybrid coating process using linear ion source (LIS) and magnetron sputtering method. The characteristics of the films were systematically investigated using FE-SEM, nano-indentation, sliding tester and AFM instrument. The microstructure of Cr-DLC films turned into the dense and fine grains with relatively preferred orientation. The thickness formed in our Cr buffer layer and DLC coating layer were obtained the 487 nm and $1.14\;{\mu}m$. The average friction coefficient of Cr-DLC films considerably decreased to 0.15 for 0.50 of uncoated SCM415 material. The hardness and surface roughness of Cr-DLC films were measured 20 GPa and 10.76 nm, respectively. And then, efficiency tests were performed on the hydraulic gear pump to investigate the efficiency performance of the Cr-DLC coated spur gear. The experimental results show that the volumetric and mechanical efficiency of hydraulic gear pump using the Cr-DLC spur gear were improved up to 2~5% and better efficiency improvement could be attributed to its excellent microstructure, higher hardness, and lower friction coefficient. This conclusion proves the feasibility in the efficiency improvement of hydraulic gear pump for industrial applications.

• Journal of Ginseng Research
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• v.43 no.3
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• pp.421-430
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• 2019

Background: The ginsenoside Rg3, one of active components of red ginseng, has chemopreventive and anticancer potential. Cancer stem cells retain self-renewal properties which account for cancer recurrence and resistance to anticancer therapy. In our present study, we investigated whether the standardized Korean Red Ginseng extract (RGE) and Rg3 could modulate the manifestation of breast cancer stem cell-like features through regulation of self-renewal activity. Methods: The effects of RGE and Rg3 on the proportion of $CD44^{high}/CD24^{low}$ cells, as representative characteristics of stem-like breast cancer cells, were determined by flow cytometry. The mammosphere formation assay was performed to assess self-renewal capacities of breast cancer cells. Aldehyde dehydrogenase activity of MCF-7 mammospheres was measured by the ALDEFLUOR assay. The expression levels of Sox-2, Bmi-1, and P-Akt and the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres were verified by immunoblot analysis. Results: Both RGE and Rg3 decreased the viability of breast cancer cells and significantly reduced the populations of $CD44^{high}/CD24^{low}$ in MDA-MB-231 cells. RGE and Rg3 treatment attenuated the expression of Sox-2 and Bmi-1 by inhibiting the nuclear localization of hypoxia inducible $factor-1{\alpha}$ in MCF-7 mammospheres. Suppression of the manifestation of breast cancer stem cell-like properties by Rg3 was mediated through the blockade of Akt-mediated self-renewal signaling. Conclusion: This study suggests that Rg3 has a therapeutic potential targeting breast cancer stem cells.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1338-1346
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• 2018

The purpose of this study is to analyze the curriculum of a university-affiliated science gifted education center based on the core competencies and to suggest a direction for improving the education at the gifted education center. For this purpose, we set the 12 core competencies as follows: 6 cognitive competencies such as knowledge, creativity, scientific thinking ability, inquiry ability, problem solving ability and fusion ability, and 6 non-cognitive competencies such as task commitment, self-directed learning ability, motivation reinforcement and challenge, communication skills, collaboration ability and leadership. The curricula of the science gifted education centers reflect all the competencies, but some competencies are only potentially included in the contents of the programs. In this study, we present examples of education programs by each competences and suggest additional descriptions for the development of gifted education centers.

• Korean Journal of Radiology
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• v.20 no.1
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• pp.158-165
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• 2019

Objective: Recent studies demonstrated that core needle biopsy (CNB) can effectively reduce the possibility of inconclusive results and prevent unnecessary diagnostic surgery. However, the effectiveness of CNB in patients with suspicious thyroid nodules has not been fully evaluated. This prospective study aimed to determine the potential of CNB to assess thyroid nodules with suspicious ultrasound (US) features. Materials and Methods: Patients undergoing CNB for thyroid nodules with suspicious features on US were enrolled between May and August 2016. Diagnostic performance and the incidence of non-diagnostic results, inconclusive results, conclusive results, malignancy, unnecessary surgery, and complications were analyzed. Subgroup analysis according to nodule size was performed. The risk factors associated with inconclusive results were evaluated using multivariate logistic regression analysis. Results: A total of 93 patients (102 thyroid nodules) were evaluated. All samples obtained from CNB were adequate for diagnosis. Inconclusive results were seen in 12.7% of cases. The diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for diagnosis of malignancy were 93.8%, 100%, 100%, 78.9%, and 95%, respectively. None of the patients underwent unnecessary surgery. The diagnostic performance was not significantly different according to nodule size. On multivariate logistic regression analysis, larger nodule size and shorter needle length were independent risk factors associated with inconclusive results. Conclusion: Samples obtained by CNB were sufficient for diagnosis in all cases and resulted in high diagnostic values and conclusive results in the evaluation of suspicious thyroid nodules. These findings indicated that CNB is a promising diagnostic tool for suspicious thyroid nodules.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.10a
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• pp.268-268
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• 2017

• 한국IT서비스학회:학술대회논문집
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• 2005.05a
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• pp.575-579
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• 2005

A Shared Services center (SSC) is created by removing common administrative functions from operational divisions within an organization, and centralizing the functions in a separate centre. SSC helps supporting organizations to focus on core activities and to achieve cost reduction as well as service quality enhancement. In contrast to many leading global companies which has been adopted SSCs from early 90's. A Company's HR SSC which has opened this year is the first genuine SSC practice in Korea. Centering on the case of A Company' s HR SSC implementation, we discussed on some practical implications for companies which has future plan to introduce a shared service center.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.854-859
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• 2008

This study describes the aging behavior of soils and its mechanism, which have been reported in the literatures mainly by Mitchell(1986) and Schmertmann(1991). It could be known that aging of soils has both positive and negative effects on mechanical properties of soils. In order to show aging effects on dam behavior, a parametric study was carried out based considering the presence of a weak area within clay core zone of the fill dam. From the comparison of results obtained from numerical analysis and filed investigation, age-softening phenomena occurred within core zone during about 30 years after its completion.

• Microbiology and Biotechnology Letters
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• v.51 no.3
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• pp.303-305
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• 2023

In this study, we report the complete genome sequence of Priestia megaterium strain HyangYak-01, which was isolated from the rhizosphere soil of Centella asiatica. The genome consists of 5,086,279 bp of sequences with 38.2 percent GC content and 5,111 coding genes. The genome contains several important genes related to plant growth-promoting activities, which were also confirmed with in vitro media assays.

• Bulletin of the Korean Chemical Society
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• v.31 no.11
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• pp.3441-3444
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• 2010