• Journal of Powder Materials
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• v.23 no.6
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• pp.409-413
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• 2016

Electrical wire explosion in liquid media is a promising method for producing metallic nanopowders. It is possible to obtain high-purity metallic nanoparticles and uniform-sized nanopowder with excellent dispersion stability using this electrical wire explosion method. In this study, Ni-Fe alloy nanopowders with core-shell structures are fabricated via the electrical explosion of Ni-Fe alloy wires 0.1 mm in diameter and 20 mm in length in de-ionized water. The size and shape of the powders are investigated by field-emission scanning electron microscopy, transmission electron microscopy, and laser particle size analysis. Phase analysis and grain size determination are conducted by X-ray diffraction. The result indicate that a core-shell structured Ni-Fe nanopowder is synthesized with an average particle size of approximately 28 nm, and nanosized Ni core particles are encapsulated by an Fe nanolayer.

• Journal of the Semiconductor & Display Technology
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• v.22 no.2
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• pp.133-137
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• 2023

This study the problem of deposition uniformity observed during Mist-CVD deposition experiments. The TRIZ's ADRIGE algorithm, a problem-solving technique, is utilized to systematically analyze the issue and propose solutions. Through problem and resource analysis, technical contradictions are identified regarding the precursor's volume and its path when it encounters the substrate. To resolve these contradictions, the concept of applying the principle of dimensional change to transform the precursor's three-dimensional path into a one-dimensional path is suggested. The chosen solution involves the design of an enhanced Mist-CVD system, which is evaluated for feasibility and analyzed using computational fluid dynamics. The analysis confirms that the deposition uniformity consistently follows a pattern and demonstrates an improvement in uniformity. The improved Mist-CVD equipment is validated through analysis, providing evidence of its feasibility and yielding satisfactory results.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2003.05b
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• pp.281-282
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• 2003

The significant spring-time phenomenon known as the "Yellow Sand" influences not only regional but also global climate. It′s believed that frequency of yellow-sand events has increased in recent years. To investigate the possible factors inducing these special strong weather phenomenon and its impacts on meteorological elements, intensive sampling will be conducted by ADEMRC/KJIST from March to May 2003. Lagrangian trajectory (forward and backward), cluster analysis, factor analysis and satellite remote sense (SRS) techniques will be employed to inspect the mechanisms of yellow-sand. (omitted)

• Applied Microscopy
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• v.47 no.2
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• pp.77-83
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• 2017

Drastic development of ubiquitous devices requires more advanced batteries with high specific capacitance and high rate capability. Large-area microstructure characterization across the stacks of cathode, electrolyte and anode might reveal the origin of the instability or degradation of batteries upon cycling charge. In this study, sample preparation methods to observe the cross-section view of the electrodes for battery in SEM and several imaging tips are reviewed. For an accurate evaluation of the microstructure, ion milling which flats the surface uniformly is recommended. Pros and cons of cross-section polishing (CP) with Ar ion and focused ion beam (FIB) with Ga ion were compared. Additionally, a modified but new cross-section milling technique utilizing precision ion polishing system (PIPS) which can be an alternative method of CP is developed. This simple approach will make the researchers have more chances to prepare decent large-area cross-section electrode for batteries.

• Journal of the Korean Society for Railway
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• v.6 no.2
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• pp.9-18
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• 2003

This paper discuss advanced safety in the railway signaling system. The specified methods and HAZOP about Hazard identification and analysis of railway signalling system were studied, and loss analysis and ALARP model in order to calculate safety as a standard capacity were proposed. It was also resulted from Hazard identification, analysis and evaluation by applying advanced safety to the railway signalling system.

• Journal of Food Hygiene and Safety
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• v.26 no.2
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• pp.125-141
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• 2011

Melamine has raised international concerns for its catastrophic health effects from tainted infant formula. This report concerns the developmental validation of a sensitive HPLC/MS/MS and GC/MS methods about melamine and cyanuric acid in human urine and serum. Analytical detection ranges of LC/MS was from 0.2 to 5.0 ng/mL and 2.0 to 60.0 ng/mL about melamine and cyanuric acid, respectively. The limits of quantification and confirmation are 0.2 ng/mL for both analytes in human urine and serum by LC/MS/MS. The range of recovery was 91.6%, and 107.6% for cyanuric acid and melamine in urine, respectively. The range of precision coefficient variation was from 2.0%, to 11.8% for cyanuric acid and melamine in urine. The range of recovery was from 94.9%, to 119.0% about cyanuric acid and melamine in serum, respectively. The range of precision coefficient variation from was 3.7%, and 13.5% about cyanuric acid and melamine in serum. Analytical detection ranges of GC/MS were 5.0 to 100.0 ng/mL about melamine and cyanuric acid, respectively. The limits of quantification and confirmation are 5.0 ng/mL for both analytes in human urine and serum by GC/MS. The range of recovery was from 83.7%, to 114.5% for cyanuric acid and melamine in urine, respectively. The range of precision coefficient variation was 3.5%, and 10.7% for cyanuric acid and melamine in urine. The range of recovery was 94.4%, and 110.7% for cyanuric acid and melamine in serum, respectively. The range of precision coefficient variation from was 3.9%, and 13.8% for cyanuric acid and melamine in serum. Several changes were taken to optimize performance by this method.

• Proceedings of the PSK Conference
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• 2001.04a
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• pp.115.1-115.1
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• 2001

• Journal of Korean Society of Steel Construction
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• v.13 no.2
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• pp.153-162
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• 2001

A direct design method of three-dimensional frames using practical advanced analysis is presented. In this method. separate member capacity checks encompassed by the code specifications are not required. because the stability of separate members and the structure as a whole can be rigorously treated in determining the maximum strength of the structures. Advanced analysis accounts for geometric and material nonlinearities. The geometric nonlinearlity is considered by the use of stability function. The material nonlinearity is accounted for using CRC tangent modulus and parabolic function. The load-displacements predicted by the proposed analysis compare well with those given by other approaches. A design example has been presented for a 22-story frame. The analysis results show that the proposed method is suitable for adoption in practice.

• Molecules and Cells
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• v.25 no.2
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• pp.163-171
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• 2008

The genus Cynodon comprises ten species. The objective of this study was to evaluate the genetic diversity of Korean bermudagrasses at the morphological, cytological and molecular levels. Morphological parameters, the nuclear DNA content and ploidy levels were observed in 43 bermudagrass ecotypes. AFLP markers were evaluated to define the genetic diversity, and chromosome counts were made to confirm the inferred cytotypes. Nuclear DNA contents were in the ranges 1.42-1.56, 1.94-2.19, 2.54, and 2.77-2.85 pg/2C for the triploid, tetraploid, pentaploid, and hexaploid accessions, respectively. The inferred cytotypes were triploid (2n = 3x = 27), tetraploid (2n = 4x = 36), pentaploid (2n = 5x = 45), and hexaploid (2n = 6x = 54), but the majority of the collections were tetraploid (81%). Mitotic chromosome counts verified the corresponding ploidy levels. The fast growing fine-textured ecotypes had lower ploidy levels, while the pentaploids and hexaploids were coarse types. The genetic similarity ranged from 0.42 to 0.94 with an average of 0.64. UPGMA cluster analysis and principle coordinate analysis separated the ecotypes into 6 distinct groups. The genetic similarity suggests natural hybridization between the different cytotypes, which could be useful resources for future breeding and genetic studies.

• Journal of Korean society of Dental Hygiene
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• v.21 no.4
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• pp.413-425
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• 2021

Objectives: This study aimed to provide basic data to lay the groundwork for the introduction of an advanced dental hygienist system by sampling dental hygienists' views about the system. Methods: A nationwide questionnaire survey was conducted targeting 857 dental hygienists working at dental hospitals and clinics, local health institutions, and educational institutions. The collected data were analyzed using frequency analysis, t-test, one-way analysis of variance (ANOVA) (Duncan as post-analysis), and crossover analysis. Results: The average interest level in the advanced dental hygienist system was 3.83±0.95 points. The necessity by field was confirmed to be the highest during dental hygiene for the elderly and persons with disabilities. The working experience necessary for becoming a specialized dental hygienist is 5.56±2.99 (years). The education period necessary for becoming a specialized dental hygienist is 77.30±77.61 (hours). The work authority level for an advanced dental hygienist was indicated to be 50 respondents (5.8%), who said they required direct guidance from a dentist, 313 respondents (48.2%) who said they needed indirect guidance from a dentist, 200 respondents (23.3%) who said OK when given an advanced dental hygienist's separate judgment, 194 respondents (22.6%), who said that the authority must be varied depending on the work. Conclusions: The interest and need of the advanced dental hygienist system were proven to be high and are expected to be applied to basic data for the introduction and settlement of the system.