• Bulletin of the Korean Mathematical Society
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• v.50 no.5
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• pp.1711-1723
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• 2013

P. V$\acute{a}$mos called a ring R 2-good if every element is the sum of two units. The ring of all $n{\times}n$ matrices over an elementary divisor ring is 2-good. A (right) self-injective von Neumann regular ring is 2-good provided it has no 2-torsion. Some of the earlier results known to us about 2-good rings (although nobody so called at those times) were due to Ehrlich, Henriksen, Fisher, Snider, Rapharl and Badawi. We continue in this paper the study of 2-good rings by several authors. We give some examples of 2-good rings and their related properties. In particular, it is shown that if R is an exchange ring with Artinian primitive factors and 2 is a unit in R, then R is 2-good. We also investigate various kinds of extensions of 2-good rings, including the polynomial extension, Nagata extension and Dorroh extension.

• Journal of Animal Environmental Science
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• v.19 no.2
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• pp.169-176
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• 2013

This survey was conducted to investigate the present conditions of operational management in the 45 animal manure public resource center (APRC) in Korea. The regional distribution, processing capacity per year, capacity of liquid fertilizer storage tank, solid-liquid separation, utilization of facilities, odor reduction facility, on-site odor strength, complained in the community, liquid fertilizer sprayed area, use the Agrix, land application recipe, composting degree, quality management and general grading were surveyed and evaluated. General grading was divided with 5 stages (very good, good, fair, lack and bad). The number of evaluated "very good" animal manure public resource center was 7, and "good" was 5 and more than "fair" was 27. However, the number of evaluated negatively including "lack" and "bad" was occupied as 40% of the 45 animal manure public resource center.

• Educational Technology International
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• v.21 no.2
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• pp.193-216
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• 2020

This study investigated university students' perspectives on good class and instructional practices through social network analysis. The subjects were 321 students in the third and fourth academic years in a Korean university. The subjects completed four open-ended questions, asking about experience of good class, good instructors' teaching practice, and their feelings and attitudes when participating in good class. As social network analysis, KrKwic (Korea Key Words in Context) was used to compute word frequencies and analyze semantic network structures and Ucinet Netdraw to assess centrality in the social network, consisting of degree centrality, closeness centrality, and between centrality. The results are as follows. First, students showed 5 keywords to depict what good class is, including 'understanding', 'example', 'video', 'interest', and 'communication'. Second, the characteristics of teaching methods by professors who practice good class indicate 'assignments', 'questions', 'understanding', 'example', and 'feedback'. Third, the top 5 keywords of students' attitudes as participating in good class are 'active', 'participation', 'focus', 'listening', and 'asking'. Last, keywords depicting desirable class that students most wanted to take next time are 'assignments', 'rewards', 'understanding', 'difficulty', and 'interest'. The findings from this study include the meanings of the semantic network structures of words in the text making up messages. Also this study can provide empirical evidence for educators and educational practitioners in higher education to create effective learning environments.

• Textile Coloration and Finishing
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• v.20 no.1
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• pp.22-27
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• 2008

Sulfadiazine and silver sulfadiazine are well-known bactericidal agent routinely used clinical settings. Antimicrobial acid dyes were synthesized by introducing sulfadiazine or silver sulfadiazine and applied on nylon fabric. The Chemical Structure of the Synthesized dyes was identified by HPLC-mass. The dyeability of synthesized acid dyes for nylon fabric was similar to commercial acid dyes. Resistance to washing, rubbing and lightfastness were good. Nylon fabrics dyed with synthesized acid dyes had good antimicrobial properties. Durable antimicrobial properties after 20 times washing have shown good result that reduction ratio of colonies, is 99.9 %. Mixed dyeing were carried out using commercial acid dyes(leveling type) and synthesized dyes. The mixed dyeings have also shown good antimicrobial properties.

• Journal of radiological science and technology
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• v.13 no.1
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• pp.11-18
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• 1990

Konica high ortho MG series has good system to develop diagnostic ability which in high speed and result in reduce $25{\sim}60%$ of exposure factors. MG film in suitable for genenal radiography which has good contrast and wide latitude. MGH is high contrast type and has a good sharpness which prevent to redusing contrast by scatter ray. Therefore, MGH is suitable to special study such as angiography.

• Toxicological Research
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• v.25 no.1
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• pp.1-8
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• 2009

Validation specifies and coordinates all relevant activities to ensure compliance with good laboratory practices (GLP) according to suitable international standards. This includes validation activities of past, present and future for the best possible actions to ensure the integrity of non-clinical laboratory data. Recently, validation has become increasingly important, not only in good manufacturing practice (GMP) institutions but also in GLP facilities. In accordance with the guideline for GLP regulations, all equipments used to generate, measure, or assess data should undergo validation to ensure that this equipment is of appropriate design and capacity and that it will consistently function as intended. Therefore, the implantation of validation processes is considered to be an essential step in a global institution. This review describes the procedures and documentations required for validation of GLP. It introduces basic elements such as the validation master plan, risk assessment, gap analysis, design qualification, installation qualification, operational qualification, performance qualification, calibration, traceability, and revalidation.

• Korean Journal of Mathematics
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• v.14 no.1
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• pp.85-93
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• 2006

A good arithmetic random number generator should possess full period, uniformity and independence, etc. To obtain the excellent random number generator, many researchers have found good parameters. Also an initial seed is the important factor in random number generator. But, there is no theoretical guideline for using the initial seeds. Therefore, random number generator is usually used with the arbitrary initial seed. Through the empirical tests, we show that the choice of the initial values for the seed is important to generate good random numbers.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.341-342
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• 2002

Although vegetable oils provide good lubricity, they still need optimization by certain additive technology for practical applications. ZDTP improve antiwear properties of vegetable oils. However the additive performance depends on quality of the base Oil. Antioxidants were applied to prevent the auto-oxidation of vegetable oils. Good synergistic effect of anti-wear and antioxidant additives was confirmed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.2
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• pp.230-237
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• 2017

Various drones have extended application area very fast. In this paper, we define two contradictions in designing a portable-size drone by using TRIZ technique. The first is a physical contradiction between high rigidity and good portability, and the second is a technical contradiction between high stability and good portability. Through TRIZ technique, six design principles, which guide direction for optimal design, were driven. Consequently, an umbrella mechanism and design criteria were proposed for a portable-size drone. Detail design is verified through finite element method. Test results for the portable-size prototype drone show good performance, and prove its usefulness to be equivalent to a general full-size drone.

• International Journal of Advanced Culture Technology
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• v.9 no.3
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• pp.68-73
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• 2021

The 'Good School Uniform' development project was conducted in consultation with Gyeonggi-do and the Gyeonggi Provincial Office of Education. The aim is to find various ways to supply school uniforms reflecting the latest trends at low prices using high-quality textile materials produced in Gyeonggi-do. From 2015, when the 'Good School Uniform' development project started, to the present, various events and fairs are making great progress. However, there are several problems in actually wearing each middle and high school student. In order to satisfy the characteristics of each school and the satisfaction of parents and students together, it is necessary to not only conduct practical research such as closer customer satisfaction surveys, industry-academia-research networks, expert interviews, and surveys, but also several supplements such as consultations between practitioners. There are many domestic studies on the development of school uniform design, but the research on the revitalization plan according to the free school uniform support is very insufficient. Moreover, it is not easy to find recent studies on the development of 'Good School Uniforms'. This study intends to study how to build a system so that the Gyeonggi-do 'Good School Uniform' development project can be used as a role model. In addition, it is expected that this study will be used as basic data for building a nationwide system such as public brand development and collaboration with small domestic companies.