• Journal of the Korea Institute of Building Construction
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• v.17 no.2
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• pp.175-181
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• 2017

The purpose of this study is evaluating the characteristics of tensile strength of UHPC and examining tensile performance of notched specimens by direct tensile test. For test variables, 120, 150, and 180MPa of target design standard strength were aimed at. With general water curing and $90^{\circ}C$ high temperature steam as curing conditions, the properties were reviewed. Overall, it was represented that the specimens of notch-type direct tensile strength concrete was effective in inducing central cracks compared with existing direct tension specimens. Through this, it was judged that data construction with high reliability was possible. Above all, in a graph of direct tensile strength and strain, in the case of steam curing at high temperature, there was great difference of initial tensile strength compared with water curing. As passing of ages, an aspect that the difference gradually decreased was shown. Maximum tensile strength was found to increase steadily with increasing age for all target design strengths in water curing, in the case of steam curing, the tendency to increase significantly due to the initial strength development effect at 7 days of age. The initial crack strength increases with age in case of underwater curing, in the case of steam curing, it was higher than that of water curing in 7 days, while the strength of 28 days was lowered. In this part, it is considered necessary to examine the arrangement condition of the steel fiber.

• The korean journal of orthodontics
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• v.35 no.3 s.110
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• pp.196-206
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• 2005

This study was undertaken to investigate the effect of vitamin C deficiency on the orthodontic tooth movement and bony remodeling processes. Thirty six male guinea pigs were divided on the basis of the given amount of vitamin C (normal group: 5mg/day, deficient group: 0.2mg/day) and 75gm of force was applied to the maxillary incisors. Experimental animals were sacrificed at day 0. day 1 day 3, day 5. day 7 and day 14 after force application and the amount of tooth movement was measured and tissues were studied histologically. The results showed that the amount of collagen fiber in the periodontal ligament and alveolar bone of the deficient group was less than that of the normal group. In the stretched side. the osteoblastic activity and alveolar bone formation of the normal group increased in a time dependent manner during experimental periods, but the deficient group showed less activity and formation. The amount of tooth movement in the deficiency group was more than in the normal group at day 0. day 1, day 3, day 5, and day 7. According to the above results, a deficiency of vitamin C resulted in a defect of collagen synthesis of the periodontium and inhibition of bone formation and stimulation of bone resorption with rapid tooth movement in early periods of force application.

• Journal of Embryo Transfer
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• v.19 no.2
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• pp.75-80
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• 2004

This study was performed to examine the cytotoxic effects of nicotine on the seminiferous tubules and Leydig cells in mice testis. A different amount of nicotine (2～15 mg/kg, for two weeks, one dose of 100 mg/kg) were administered to four-month male mice, and then the optical microscopic findings of its effect on testis of the mice are as follows: 1. The group that 2 mg/kg of nicotine was administered showed normal findings that nucleus and cytoplasm of Leydig cells are distinct, while the other group that 5 mg/kg of nicotine was given to showed nucleus and cytoplasm are swollen and thickened a little, and slightly dyed. 2. The group that 10 mg/kg of nicotine was given had irregular arrangement of spermatogenesis inside seminiferous tubules so it was impossible to distinguish phages of seminiferous tubules. It was also impossible to observe cells due to fusion of their nucleuses, and distinct cytoplasm. 3. The group that 15 mg/kg of nicotine was administered showed destruction of nucleuses and cytoplasm of spermatocytes and sperms and a fill of fibered connective tissues so that it is impossible to observe rumens of seminiferous tubules.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.9
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• pp.1469-1475
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• 2004

Skin is the most frequently exposed tissues to oxidative stress from exogenous and endogenous sources. Dietary antioxidants, which suppress oxidative stress including reactive oxygen metabolites, play an important role in protecting skin from deleterious reactive oxygen species. Kimchi containing lots of antioxidative compounds shows anti-aging effect on skin. Therefore the morphologic changes on the skin of hairless mice fed diets containing Korean cabbage, mustard leaf, and buchu kimchi for 16 weeks were determined. Although epidermal thickness was decreased with age, kimchi prevented this thinning of epidermis compared to control group. In kimchi groups, the staining area of cytokeratin was smaller and stratum corneum was thinner than control group. It suggests that various kinds of kimchi diets prevent the increase of keratinization in epidermis with aging. Type Ⅳ collagen, a major structural protein of basement membrane supporting matrices, existed greater amount in kimchi groups than control group, especially in mustard leaf kimchi group. Rough endoplasmic reticulum (RER) of fibroblast was well developed in dermis of Korean cabbage and mustard leaf kimchi groups, which means collagen synthesis at dermis increased in those kimchi groups. This morphological changes of skin suggest that kimchi consumption can retard skin aging due to the presence of antioxidant and anti-aging compounds, especially some components of mustard leaf kimchi may largely affect on the skin rejuvenescence.

• Journal of the Korean Arthroscopy Society
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• v.5 no.1
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• pp.7-12
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• 2001

Purpose : We observed usability of allograft by evaluating the clinical results, second look arthroscopic and histologic findings at last follow up after anterior cruciate ligament(ACL) reconstruction using by fresh frozen Achilles allograft. Materials and Methods : We analyzed in 58 patients(59 cases) by subjective and objective parameters, Telos stress arthrometer and Modified Feagin Scoring System. The average age and follow up period was 25 years(ranging from 18 to 49 years), and 15 months(ranging from 12 to 19 months). Among them we studied second look arthroscopic and histologic findings in 16 patients. Results : The mean Lysholm Score wits improved from 60 to 88.2 as well the anterior translation was improved from 7.1 min to 2.3mm at last follow up. The second look arthroscopic findings were close to normal in ligament thickness, tension and showed revasculization at the holly attachment site. Light microscope(LM) findings showed dense cellularity like a normal ligament. In electron microscope(EM) collagen fibrils showed parallel arrangement longitudinally and unimodal pattern diameter close to normal tissue in the transverse section. Conclusion : We think that the fresh frozen Achilles allograft is a good substitution of autograft in cruciate ligament reconstruction.

• Journal of Korean Ophthalmic Optics Society
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• v.3 no.1
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• pp.93-101
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• 1998

The present study was conducted to investigate the structural changes in rat cornes. Sixty eyes from one-day-old uneyed rats, fourty eyes from 10-weeks-old adult rats were used. With the increase of age, the epithelial layer was thickened by the addition of new successive cellular layers. Then, the new-born rat's epithelial cells formed a pentagonal shape, and the quality of decidual cells showed a high electron-density, although the boundary between cells was distinctive. The newly produced cells showed a low electron-density so that there was the distinctive difference between light and darkness. In Bowman's layer, collagen fibrils demonstrate a regularly arranged structure along with the age. In stroma's layer, the density of keratocytes was decreased and thereby progressively flattened during the development. The collagenous layer of the adult rats was more distinctive than that of the new-born rats in a form of vertical and horizontal parallel alignment running vertically and horizontally. Descemet's membrane changed its structure significantly along with the age. It changed the shape from "banded-layer" to "non-banded layer" gradually. The thickness was also increased along with the age. Regardless of developmental stages, the endothelium is usually monolayer. During the developmental process, endothelial cells disappeared, so the density of endothelium was also decreased. The empty spaces were replaced by the expansion of adjacent cells.

• Journal of Life Science
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• v.25 no.11
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• pp.1223-1229
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• 2015

Oryzalin is a dinitroaniline herbicide, which disrupts the arrangement of microtubules. Microtubules and microfilaments are cytoskeletal components that are thought to play a role in the sedimentation of statoliths and the formation of cell walls. Statoliths regulate the perception of gravity by columella cells in the root tip. To determine the effect of oryzalin on the gravitropic response, ethylene production in primary roots of maize was investigated. Treatment with 10^-4 M oryzalin to the root tip inhibited the growth and gravitropic response of the roots. However, the treatment had no effect on the elongation zone of the roots. An application of 10^-4 M oryzalin for 15 hr to the root tip caused root tip swelling. The application of 1-aminocycopropane-1-carboxylic acid (ACC), a precursor of ethylene, to the root tip also inhibited the gravitropic response. To understand the role of oryzalin in the regulation of the growth and gravitropic response of roots, ethylene production in the primary roots of maize was measured following treatment with oryzalin. Oryzalin stimulated ethylene production via the activation of ACC oxidase (ACO) and ACC synthase (ACS), and it increased the expression of ACO and ACS genes. Indole-3-acetic acid (IAA) played a key role in the asymmetric elongation rates observed during gravitropism. The results suggest that oryzalin alters the gravitropic response of maize roots through modification of the arrangement of microtubules. This might reduce the distribution of IAA in the upper and lower sides of the elongation zone and increase ethylene production, thereby inhibiting growth and gravitropic responses.

• Journal of the Korean Wood Science and Technology
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• v.43 no.6
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• pp.868-875
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• 2015

In order to replace existing slit type steel plate on the wooden structure joint, the FRP-reinforced laminated plates were produced. Four types of FRP-reinforced laminated plates were produced according to the type of reinforcement and adhesive, and before applying to the joint, the adhesion performance test according to KSF 3021 and KSF 2160 and the Compact Tension (CT) type fracture toughness test specified in ASTM D5045-99 were carried out. As a result of adhesion performance test, all GFRP textile, GFRP sheet, and GFRP Textile-Sheet type FRP-reinforced laminated plates satisfied the requirement of soaking delamination percentage with smaller than 5% based on KS standard. However, aramid type specimen satisfied the standard as the soaking delamination percentage of 4.8% but it did not satisfied the standard as the water proof soaking delamination percentage of 70%. As a result of fracture toughness test, the volume ratio of reinforcement to timber became 23% so that the strength of FRP-reinforced laminated plates increased by two to four times in comparison to the control specimen. It was confirmed that the GFRP Textile-Sheet type specimen was most resistant to the fracture most since the ratio of stress intensity factor compared with that of the control increased to 61% owing to the parallel arrangement of glass fiber to the load. As a result of tensile shear strength test using FRP-reinforced laminated plates and nonmetal dowels, it is about 12% lower than metal connectors.

• Korean Journal of Poultry Science
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• v.38 no.1
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• pp.13-19
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• 2011

In January 2010, high mortalities of ducklings occurred in two adjacent farms. Ducklings in farm A showed neurologic signs including paddling, opisthotonus and lameness, but ducklings from farm B had no specific clinical signs. At post mortem, diffused hemorrhagic spots in the liver and hemorrhages in the small intestine were observed in ducklings from farm A, and ducklings from farm B had only proventricular ulceration. Microscopically, multiple necrosis of hepatocytes, hyperplasia of the bile ducts, hemorrhages, infiltration of lymphocytes and bacterial colonies were commonly observed in the liver of ducklings from both farms. Also, type A and C duck hepatitis virus (DHV) were isolated from farm A and farm B, respectively and Salmonella typhimurium was commonly isolated and identified serologically and biochemically. To our knowledge, this is the first report about the co-infection of DHV and Salmonella typhimurium in ducklings, and co-circulation of type A and C duck hepatitis viruses in Korea.

• Applied Microscopy
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• v.41 no.4
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• pp.229-234
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• 2011

The occurrence of nuclear inclusions has been reported in various plant groups from primitive ferns to higher flowering plants. Their presence within a group seems to be randomly distributed without any phylogenetic relationships among species. According to the current survey, nuclear inclusions have been widely documented in more than several hundreds of species from various families of plants. The morphology and internal structures of nuclear inclusions are diverse and at least five types of inclusions develop within plant nuclei; amorphous, crystalline, fibrous, lamellar, and tubular form. Among these types, crystalline inclusions are the ones that are the most frequently reported. The inclusions are not bound by membranes and appear to be related to the nucleoli, either spatially by a close association or by an inverse relationship in size during development. The idea that nuclear inclusions are of a proteinaceous nature has been widely accepted. Further link to nucleolar activity as a protein storing site has also been suggested based on the association between the nucleolus and nuclear inclusions. Various investigations of nuclear inclusions have revealed more information about their structural features, but characterizing their precise function and subunit complexity employing molecular analysis and 3-D reconstruction remains to be elucidated. Tilting and tomography of serial sections with appropriate image processing can provide valuable information on their subunit(s). The present review summarizes discussion about different nuclear inclusions in plants from previous works, giving special attention to their fine, ultrastructural morphology, function, and origin.