• The korean journal of orthodontics
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• v.50 no.6
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• pp.391-400
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• 2020

Objective: Increased gingival elasticity has been implicated as the cause of relapse following orthodontic rotational tooth movement and approaches to reduce relapse are limited. This study aimed to investigate the effects of sulforaphane (SFN), an inhibitor of osteoclastogenesis, on gene expression in gingival fibroblasts and relapse after rotational tooth movement in beagle dogs. Methods: The lower lateral incisors of five beagle dogs were rotated. SFN or dimethylsulfoxide (DMSO) were injected into the supra-alveolar gingiva of the experimental and control group, respectively, and the effect of SFN on relapse tendency was evaluated. Changes in mRNA expression of extracellular matrix components associated with gingival elasticity in beagles were investigated by real-time polymerase chain reaction. Morphology and arrangement of collagen fibers were observed on Masson's trichrome staining of buccal gingival tissues of experimental and control teeth. Results: SFN reduced the amount and percentage of relapse of orthodontic rotation. It also decreased the gene expression of lysyl oxidase and increased the gene expression of matrix metalloproteinase (MMP) 1 and MMP 12, compared with DMSO control subjects. Histologically, collagen fiber bundles were arranged irregularly and were not well connected in the SFN-treated group, whereas the fibers extended in parallel and perpendicular directions toward the gingiva and alveolar bone in a more regular and well-ordered arrangement in the DMSO-treated group. Conclusions: Our findings demonstrated that SFN treatment may be a promising pharmacologic approach to prevent orthodontic rotational relapse caused by increased gingival elasticity of rotated teeth in beagle dogs.

• Journal of the Korea Convergence Society
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• v.12 no.4
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• pp.87-94
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• 2021

While the shielding substances of radiation shields in medical institutions are beginning to be replaced by environmentally friendly materials, radiation protection according to the shielding properties of environmentally friendly substances is becoming an important factor rather than the existing lead shielding properties. Tungsten and barium sulfate are representative shielding materials similar to lead, and are made in sheets or fiber form with eco-friendly materials. Ytterbium is an impermeable material used as a fluorine compound in the dental radiation field. This study aims to evaluate the shielding performance in the x-ray shielding area by comparing the shielding properties of ytterbium by energy band and that of existing eco-friendly materials. When three types of shielding sheets were fabricated and tested under the same process conditions, the shielding performance of the medical radiation area was about 5 % difference from tungsten. Furthermore, shielding performance was superior to barium sulfate. In the cross-sectional structure of the shielding sheet, there was a disadvantage that the arrangement of particles was not uniform. Ytterbium oxide showed sufficient potential as a medical radiation shielding material, and it is thought that it can improve the shielding performance by controlling the particle arrangement structure and particle size.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.1
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• pp.40-47
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• 2022

In this study, the direction of the steel fibers mixed in the normal mortar and the steel slag mortar was arranged in the circumferential direction by using an electromagnetic field, and a double punch test was performed to evaluate the effect of magnetic filed exposure on tensile strength and on fracture energy. As a result of the experiment, it was confirmed that it is possible to arrange the steel fibers in the circumferential direction. Tensile strength and displacement at failure were also increased according to the arrangement of steel fibers due to exposure to electromagnetic fields. On the other hand, the fracture energy hardly increased. It is considered that there was a limit in resisting crack growth because the area where the arrangement of steel fibers could be adjusted under the electromagnetic field was not deep to center of specimen and the end shape of the steel fibers were straight not hooked. Additional research is needed to address these issues.

• Clinical and Experimental Reproductive Medicine
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• v.49 no.4
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• pp.259-269
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• 2022

Objective: Animal-free scaffolds have emerged as a potential foundation for consistent, chemically defined, and low-cost materials. Because of its good potential for high biocompatibility with reproductive tissues and well-characterized scaffold design, we investigated whether polyglycolic acid (PGA) could be used as an animal-free scaffold instead of natural fibrin-agarose, which has been used successfully for three-dimensional human endometrial cell culture. Methods: Isolated primary endometrial cells was cultured on fibrin-agarose and PGA polymers and evaluated various design parameters, such as scaffold porosity and mean fiber diameter. Cytotoxicity, scanning electron microscopy (SEM), and immunostaining experiments were conducted to examine cell activity on fabricated scaffolds. Results: The MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay and SEM results showed that endometrial cells grew and proliferated on both scaffolds. Immunostaining showed cytokeratin and vimentin expression in seeded cells after 7 days of culture. On both scaffolds, an epithelial arrangement of cultured cells was found on the top layer and stromal arrangement matrix on the bottom layer of the scaffolds. Therefore, fibrin-agarose and PGA scaffolds successfully mimicked the human endometrium in a way suitable for in vitro analysis. Conclusion: Both fibrin-agarose and PGA scaffolds could be used to simulate endometrial structures. However, because of environmental and ethical concerns and the low cost of synthetic polymers, we recommend using PGA as a synthetic polymer for scaffolding in research instead of natural biomaterials.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.5
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• pp.135-142
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• 2022

In this study, lap spliced ultra-high strength reinforced concrete beams were tested and the code criteria for calculating the lap splice length which was affected by the transverse reinforcement and concrete covering performance were reviewed. The main variables for test were set as fiber volume fraction and transverse reinforcing bar arrangement to improve the confining performance of the concrete cover. The change of the confining performance of concrete cover according to the increase in the fiber mixing amount at 1% and 2% volume ratio was examined, and D10 stirrups with a spacing of 100 mm were placed in the lap spliced region. As a result of the test, the specimens confined by the stirrups showed a sudden drop of load bearing capacity with horizontal cracking at the position of tensile longitudinal reinforcement. However, horizontal cracks were not appeared at the location of longitudinal reinforcement for the specimens with steel fiber. And these specimens showed gradual decrease of load bearing capacity after experiencing peak load. In particular, it was found that the strain at the position of the tensile longitudinal reinforcements of the specimens to which the mixing ratio of 2% was applied exceeds the yield strain. As a result of measuring the strain on the concrete surface, it was found that the fiber was more effective in preventing damage to the concrete surface than the stirrups for short lap spliced region.

• Journal of the Korean Home Economics Association
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• v.27 no.2
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• pp.21-30
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• 1989

The U.S. response to increased international competition was examined in the present study in order to have more comprehensive understanding of the U.S. textile and clothing market. The method employed to conduct the study was the analysis of the written materials, interview with professionals, and the survey of the actual situations of the U.S. textile and apparel industries. The results are summarized as follows; 1. Official U.S. textile and apparel trade policy has been quite has been quite protective since 1950's. The protective trend has been embodied in Japan Cotton Textile Export Control (reciprocal trade agreement signed by the U.S. and Japan in 1957), Short Term Arrangement Regarding International Trade in Cotton Textiles, Long Term Cotton Textile Arrangement (1962∼1973), and Multi-fiber Arrangement (1974∼). Other governmental programs designed to improve the competitiveness of the U.S. textile and apparel industries include Long-term Textile and Apparel Products Export-expansion Program, and 807 Trade to take labor cost advantage. 2. Along with the quite protective governmental trade policy, the corporate responses have been made such as new sourcing mixes, investment in technology, specialization in the textile and apparel industries, and recent strategies pursued by retailer's. The apparel industry was subject to pressure from imports that increased at moderate levels, and the U.S. textile and apparel industries have made extensive efforts to adjust to the increasing competition from abroad. The textile and apparel industries have taken steps to increase labor productivity through automation, to speed management to create and introduce new products and new methods, and have lowered indirect overhead costs. Several industrywide promotion campaigns have attempted to establish a greater public awareness of international competition and to develop a preference for apparel produced in the United States. 3. Regarding these response of the U.S. and other situations of world textile and apparel trade market, much of the sense of crisis that pervades Korean textile and apparel industries has to do with the problem of adjusting government and corporate policy. Textile and apparel industry of Korea faces on going pressure to reduce costs, improve quality, increase service, develop new markets, diversify, and differentiate itself from its foreign competitors. The strategies that have been adopted in the past have generally worked in the past, but the time has come to adopt strategies that reflect present conditions. If this is not done, then we stand to lose large segments of these industries, which once lost will not easily be regenerated.

• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.313-324
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• 2010

In this study, an unbraced five-story steel-framed structure was designed in accordance with KBC2005 to understand the features of structural behavior for the arrangement of semi-rigid connections. An inelastic time history analysis of structural models was performed, wherein all the connections were idealized as fully rigid and semi-rigid. Additionally, horizontal and vertical arrangements of semi-rigid connections were used for the models. A fiber model was utilized for the moment-curvature relationship of a steel beam and a column, a three-parameter power model for the moment-rotation angle of the semi-rigid connection, and a three-parameter model for the hysteretic behavior of a steel beam, column, and connection. The base-shear force, top displacement, story drift, required ductility for the connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were investigated using four earthquake excitations with peak ground acceleration for a mean return period of 2,400 years and for the maximum base-shear force in the pushover analysis of a 5% story drift. The maximum base-shear force and story drift decreased with the outer vertical distribution of the semi-rigid connection, and the required ductility for the connection decreased with the higher horizontal distribution of the semi-rigid connection. The location of the maximum story drift differed in the pushover analysis and the time history analysis, and the magnitude was overestimated in the pushover analysis. The outer vertical distribution of the semi-rigid connection was recommended for the base-shear force, story drift, and required ductility for the connection.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.10
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• pp.1325-1332
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• 2010

This study was conducted to evaluate the effects of the particle size (PS) of alfalfa hay (AH) and soybean hull (SH) on milk production of dairy cows and the population of major cellulolytic bacteria in the rumen. Eight lactating Holstein cows, averaging $590{\pm}33\;kg$ BW and $47{\pm}13$ days in milk (DIM), were assigned in a $4{\times}4$ Latin square design to a $2{\times}2$ factorial arrangement of treatments: alfalfa hay particle size (fine vs. coarse) combined with soy hull (zero or substituted as 50% of AH). The cows were fed diets formulated according to NRC (2001). Physically effective factor (pef) and physically effective fiber (peNDF) contents of diets increased by increasing AH particle size and inclusion of SH in the diets (p<0.01). Dry matter intake was not significantly affected by treatments but intake of peNDF was increased marginally by increasing the PS of AH (p = 0.08) and by SH inclusion (p<0.01) in the diets. Milk production was increased by feeding diets containing SH (p = 0.04), but it was not affected by the dietary PS. Milk fat content was increased by increasing AH particle size (p = 0.03) and decreased by SH substitution for a portion of AH (p<0.01). The numbers of total bacteria and cellulolytic species were not affected by PS of AH or by SH. F. succinogenes was the most abundant species in the rumen followed by R. albus and R. flavefaciens (p<0.01). This study showed that SH cannot replace the physically effective fiber in AH having either coarse or fine particle size. In diets containing SH, increasing of diet PS using coarse AH can maintain milk fat content similar to diets without SH. Particle size and peNDF content of diets did not affect the number of total or fibrolytic bacteria in the rumen.

• Asian-Australasian Journal of Animal Sciences
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• v.8 no.3
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• pp.231-239
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• 1995

Alley cropping field experiment has been carried out for 24 months in lime-stone based dryland farming area of southern Bali to study the chemical composition and nutritive value of 16 provenances of Gliricidia sepium The design was a completely randomized block: arrangement, consisted of 16 treatments (G. sepium provenances) and 6 blocks as replications with 12 plants per provenance. Of the 16 gliricidia provenances, six were from Mexico (M), four were from Guatemala (G), one each was from Colombia (C), Indonesia (I), Nicaragua (N), Panama (P), Costa Rica (R) and Venezuela (V). After 12 months establishment, the gliricidia were lopped at 150 cm height regularly 4 times a year, twice during the 4 months wet season and twice during the 8 months dry season. The highest ash, mineral, total soluble phenol, prussic acid and digestibility were in V1; the highest crude fiber component was in M39; the highest gross energy was in P13, while the highest organic matter was in M35. Based on the highest nutritive constituents, V1, C24 and G14 were ranked first, second and third respectively, while based on the lowest non-nutritive constituents C24, V1 and N14 were ranked first, second and third, respectively. The importance of such provenances as source of nutrients for the ruminant during the dry season were discussed.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.109-116
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• 2014

The flexural behavior test of UHPC segmental box girder which has 160 MPa compressive strength and 15.4 m length was carried out. The effect of steel fibers in combination with reinforcing bars on improving the ductile performance of UHPC box girder was evaluated by comparing the flexural behavior of the UHPC segmental box girders made by the two kinds of mixing portion. The test variables are volume fraction of steel fibers and the arrangement of reinforcing bars. The behavior of UHPC box girder BF2 composed of 1% volume fraction of steel fibers and longitudinal reinforcing bars in web and upper flange with stirrup showed the similar ductile behavior with the girder BF1 composed of 2% volume fraction without stirrup in elastic stress region. But BF1 had the better stiffness and showed the more ductile behavior in inelastic stress region. Segmental interfaces of UHPC box girder have not any crack and slide until the final flexural collapse load.