• Journal of Preventive Medicine and Public Health
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• v.54 no.1
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• pp.31-36
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• 2021

Objectives: Non-traditional materials are used for mask construction to address personal protective equipment shortages during the coronavirus disease 2019 (COVID-19) pandemic. Reusable masks made from surgical sterilization wrap represent such an innovative approach with social media frequently referring to them as "N95 alternatives." This material was tested for particle filtration efficiency and breathability to clarify what role they might have in infection prevention and control. Methods: A heavyweight, double layer sterilization wrap was tested when new and after 2, 4, 6, and 10 autoclave sterilizing cycles and compared with an approved N95 respirator and a surgical mask via testing procedures using a sodium chloride aerosol for N95 efficiency testing similar to 42 CFR 84.181. Pressure testing to indicate breathability was also conducted. Results: The particle filtration efficiency for the sterilization wrap ranged between 58% to 66%, with similar performance when new and after sterilizing cycles. The N95 respirator and surgical mask performed at 95% and 68% respectively. Pressure drops for the sterilization wrap, N95 and surgical mask were 10.4 mmH2O, 5.9 mmH2O, and 5.1 mmH2O, respectively, well below the National Institute for Occupational Safety and Health limits of 35 mmH2O during initial inhalation and 25 mmH2O during initial exhalation. Conclusions: The sterilization wrap's particle filtration efficiency is much lower than a N95 respirator, but falls within the range of a surgical mask, with acceptable breathability. Performance testing of non-traditional mask materials is crucial to determine potential protection efficacy and for correcting misinterpretation propagated through popular media.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.493-497
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• 2011

The basic properties and electrical characteristics of sputtering films deposited with a commercial cast target and spark plasma sintering (SPS) were compared and analyzed. The results, revealed that, the Al film prepared by heating at $60^{\circ}C/min$ (SPS process) showed a specific resistance similar to the commercial cast Al film. In addition, the results of XRD, SIMS and TEM, showed that there was not much difference in the crystal structure and impurities between the two films. Consequently, the SPS Al target was found to have properties quite similar to the commercial one and it is expected to be applied in future research to the metal wiring material for semiconductor/display devices.

• The Korea Journal of Herbology
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• v.36 no.1
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• pp.77-85
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• 2021

Objective : This study was designed to investigate effect of immature fruits from Citrus unshiu Markovich to mature them on antioxidative and antiaging-related enzyme activities in vitro. Methods : Fruits from Open field-cultivated C. unshiu Markovich (ripe and unripe fruits of Citri) made a purchase in Jeju island. We measured total polyphenol and flavonoid contents in mature C. unshiu Markovich (MC) and immature C. unshiu Markovich (IMC) 70% ethanol extract. DPPH free radical, ABTS radical, and hydroxyl radical scavenging activities in both extracts were determined. Also, reducing power, SOD-like activities, elastase inhibition, and collagenase inhibition activities of these extract were assayed at 5, 1, 0.5, and 0.1 mg/㎖. Results : The total polyphenol contents in the ethanol extract of IMC were higher than those of MC (26.99 ± 0.89 mg/TAEg). And total flavonoid contents in them were very similar to both extract (MC; 7.25 ± 0.4 mg/RUEg and IMC; 7.44 ± 0.18 mg/RUEg). DPPH free radical scavenging activities, ABTS radical scavenging capacity, reducing power, and SOD-like activities of IMC-treated group showed significant increase compared to those of MC group in all treated concentrations. Particularly, DPPH free radical scavenging and elastase inhibition activities in IMC-treated group at 5 mg/㎖ showed similar with positive control group. Besides, IMC extract at 5 mg/㎖ concentration surpassed positive control (BHA or Vit. C) in SOD-like activities and ABTS radical scavenging capacity. Conclusion : These results suggest that IMC ethanol extract may be used as a natural antioxidant and a antiaging material for development of functional foods and cosmeceuticals.

• Journal of the Korea Fashion and Costume Design Association
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• v.24 no.2
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• pp.73-84
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• 2022

Based on the method of marking the size of children's wear suggested by Korean Agency for Technology and Standards, this study classified the heights of school-aged girls by 10cm. The purpose of this study is to provide foundational material by analyzing and comparing the characteristics of torso types. The author analyzed the height section of 130 to 139.9cm, which the majority of subjects fell into, and concerning the method of research, this study statistically analyzed body sizes and calculated items related to 162 persons' torso types out of the 6th Korean Body Size Data. According to the results, eight factors were extracted, and the total explanatory variate of all the factors was found to be 81.93%. According to the results of cluster analysis with it as an independent variable, three types were drawn. Type 1 (41.4%) was found to be the thickest in the torso and round and severely curved in the sectional form of the circumference item. RegardingType 2 (25.9%), the horizontal size of the torso is similar to that of Type 1: the upper body is long, and the sectional form of the circumference item is oval-shaped. Regarding Type 3 (32.7%), mean values are similar to those of Type 2 overall: the upper body is short, and the body is the most upright. In conclusion, according to the results of analyzing torso types, the types and average values indicate significant differences in the height section of 130~139.9cm. This implies that when making ready-made clothes, it is necessary to come up with the sizes of more detailed items in relation with height. It is expected that the findings of this study will be utilized as basic data when children's wear companies develop prototypes and use grading variances according to the variations of size.

• Smart Structures and Systems
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• v.30 no.1
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• pp.49-62
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• 2022

Experimental and discrete element methods were used to investigate the effects of triple joints lengths and triple joint angle on the failure behavior of rock mass under uniaxial compressive test. Concrete samples with dimension of 20 cm × 20 cm × 5 cm were prepared. Within the specimen, three imbedded joint were provided. The joint lengths were 2 cm, 4cm and 6 cm. In constant joint lengths, the angle between middle joint and other joints were 30°, 60°, 90°, 120° and 150°. Totally 15 different models were tested under compression test. The axial load rate on the model was 0.05 mm/min. Concurrent with experimental tests, the models containing triple joints, length and joint angle are similar to the experiments, were numerical by Particle flow code in two dimensions (PFC2D). Loading rate in numerical modelling was 0.05 mm/min. Tensile strength of material was 1 MPa. The results show that the failure behaviors of rock samples containing triple joints were governed by both of the angle and the length of the triple joints. The uniaxial compressive strengths (UCS) of the specimens were related to the fracture pattern and failure mechanism of the discontinuities. Furthermore, it was shown that the compressive behavior of discontinuities is related to the number of the induced tensile cracks which are increased by decreasing the joint length. Along with the damage failure of the samples, the acoustic emission (AE) activities are excited. There were only a few AE hits in the initial stage of loading, then AE hits rapidly grow before the applied stress reached its peak. In addition, every stress drop was accompanied by a large number of AE hits. Finally, the failure pattern and failure strength are similar in both methods i.e., the experimental testing and the numerical simulation methods.

• The Korea Journal of Herbology
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• v.34 no.1
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• pp.59-65
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• 2019

Objectives : This study reviewed the antioxidant activity of each part of Portulacae Herba (PH) in order to better analyze the possibility of PH being used as a natural material. Methods : The root, stem, and leaves of the PH were separated, dried at $50^{\circ}C$, put in a 70% ethanol and then extracted three times every six hours. Antioxidant activities was performed by measuring the total polyphenol and total flavonoid contents, DPPH, ABTS, nitrite, hydroxyl radical scavenging activity, and $Fe^{2+}$ chelating. Results : The total polyphenol and total flavonoid contents was highest in the root, then the leaves, and lastly the stem. DPPH and ABTS radical scavenging activities for the root extract indicated the highest activity followed by the leaf and stem extracts. It also showed similar activity to that of the ascorbic acid. Hydroxyl radical scavenging activity and $Fe^{2+}$ chelating activity resulted to be highest in the root extract and then the leaf and stem extracts. Nitrite scavenging activity decreased with higher pH levels, and activity was highest in the order of root extract, leaf extract, and stem extract. Also, in reaction to a solution with a pH 1.2 level, the root extract showed similar scavenging activity to that of BHT. Conclusions : Therefore, based on the above results, it was verified that the roots of PH have a high antioxidant level, and they can be considered to have potential to be applied to functional food, cosmetics, and medicine with antioxidant efficacy.

• Publications of The Korean Astronomical Society
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• v.37 no.3
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• pp.35-47
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• 2022

This study investigated the stone Angbu-ilgu (scaphe sundial) of the Korea Meteorological Administration (KMA) and the Seoul Museum of History (SMH). Since the first Angbu-ilgu was produced in Korea in 1434 (the year of the reign of King Sejong), Angbu-ilgu has been reproduced with various materials. The upper surface of these two stone Angbu-ilgus symbolizes the horizon. On the hemisphere concave at the center of the horizon, the South Pole, the time line, and the season line are engraved. On the horizon of both the KMA and SMH Angbu-ilgus, the schematic, typeface, and composition of the inscription completely coincide with each other. In this study, it was estimated that the appearance of the KMA Angbu-ilgu, which was damaged at some point previously at least once, was similar to that of the SMH Angbu-ilgu, and this means that it is superficially similar with Treasure No 840, the stone horizontal sundial. In the concave hemisphere of both the stone Angbu-ilgus of the KMA and SMH, there are hour lines and 24 solar-term lines (13 line), and there is an intersection point where these lines meet the horizon, respectively. It can be verified that these intersections of these two Angbu-ilgus can be calculated as having a latitude of +37°39'15". The hour lines of the two stone Angbu-ilgus show that they were made after about 1900.

• Journal of Korea Foundry Society
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• v.42 no.3
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• pp.153-160
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• 2022

The effect of thickness on the microstructure and the mechanical properties of centrifugal cast 625 was investigated. Centrifugal cast 625 with various thickness of 10, 17 and 50mm showed partially columnar grained structure 8, 12.3 and 18.5mm respectively from the outer surface. Secondary dendrite arm spacing in the columnar grains slightly increased with increasing casting thickness. Tensile strength of the columnar region was similar regardless of casting thickness. Solidification behavior of the columnar grained region is similar to that of directional solidification, thus solidification rate in the centrifugal cast tube was extrapolated from the secondary dendrite arm spacing data of the directionally solidified material. The equiax grained region formed interior of the thick castings. The tensile strength of the equiaxed region showed the average value of the columnar region which is presumably originated from the grain structure rather than secondary dendrite arm spacing.

• Safety and Health at Work
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• v.14 no.1
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• pp.50-58
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• 2023

Background: Occupational health services are not available for more than 80% of the global workforce. This pertains especially to informal workers, workers in agriculture and in small enterprises, and self-employed. Many are working in hazardous conditions. The World Health Organization, the International Labor Organization, the International Commission on Occupational Health, and the World Organization of Family Doctors promote as part of a solution, basic occupational health services (BOHS) integrated in primary or community health care. Quality information on this topic is difficult to find. The objective of this study is to develop an open access bibliography, a repository, referring to publications on BOHS and similar innovations, to support progress and research. Methods: The database design and sustaining literature searches (PubMed, Google Scholar, SciELO) are described. For each publication selected, basic bibliographic data, a brief content description considering copyright restrictions, and a hyperlink are included. Results: Searches resulted in a database containing 189 references to publications on BOHS such as articles in scientific journals, reports, policy documents, and abstracts of lectures. A global perspective is applied in 43 publications, a national or regional perspective is applied in 146 publications. Operational and evaluative research material is still scarce. Examples of references to publications are shown. Conclusion: The repository can inspire pioneers by showing practices in different countries and can be used for reviews and in-depth analyses. Missing publications such as from China, Russia, Japan, Republic of Korea, and Spanish/Portuguese speaking countries, can be added in the future, and translated. Search functions can be developed. International collaboration for the promotion of occupational health coverage for all workers must be intensified.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2020.08a
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• pp.47-47
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• 2020

The Korean National Agrobiodiversity Center holds the more than 1300 accessions of proso millet, but a large portion of accessions are landrace of Korea that has very similar traits. To comprehend the maximum genetic diversity of this crop, a core collection with minimum number of accessions will facilitate easy access to genetic material. Here we assessed the genetic diversity and population structure in a germplasm collection of 830 accessions by employing EST-SSR markers and morphological traits. A total of 107 alleles were detected with an average allele number of 4.9 per locus among the 830 accessions based on 37 EST-SSR markers. The number of alleles per locus ranged from 2 to 7. Polymorphism information content and expected heterozygosity ranged from 0.06 to 0.68 (mean = 0.21) and 0.06 to 0.73 (mean = 0.23), respectively. The germplasm collection was separated into two groups based on population structure analysis, whereas principal coordinate analysis (PCoA) could not cluster accessions according to their geographic origin. Subsequently, a preliminarily developed core collection with a total of 141 accessions (17%) was selected from the whole set of germplasm by combining allelic variations of EST-SSR markers and eight different phenotypic traits. The core collection optimally represented the whole germplasm collection and displayed a similar level of PCoA value and genetic variation from the initial collection. The results obtained here provide a primary resource for further genetic analysis and establish a reference for further development of appropriate genetic breeding strategies.