• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.279-284
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• 1994

Fracture mechanics does work for concrete, provided that one used a proper, nonlinear form of fracture mechanics in which a finite nonlinear zone at fracture front is being considered. The fracture process zone is a region ahead of a traction-free crack, in which two major mechanisms, microcracking and bridging, play important rules. The toughness due to bridging is dominant compared to the toughness induced by the microcracking, so that the bridging is the dominant mechanism governing the fracture process of concrete. In this paper the bridging zone, which is a part of extended macrocrck with stresses transmitted by aggregates in concrete, is modelled by a Dugdale-Barenblatt type model with lenear tension-softening curve for the analyses of crack growth in concrete Finite element technique is shown for inplementation of the model.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1262_1263
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• 2009

Programmable Metallization Cell (PMC) is a memory device based on the electrolytical characteristic of chalcogenide materials. In this study, we investigate the nature of thin films formed by photo doping of Ag ions into chalcogenide materials for use in solid electrolyte of programmable metallization cell devices. We were able to do more economical approach by using copper which play an electrolyte ions role. The results imply that a Ag-rich phase separates owing to the reaction of Ag with free atoms from chalcogenide materials.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.7
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• pp.851-858
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• 2011

Nanopositioning technologies play an important role in the progress of electronics, optics, bio-engineering and various nano-scale technologies. As a result, various practical nanopositioning methods have been successfully introduced. Flexure mechanism is a valuable method in nanopositioning because of smooth and friction-free motion and the infinitesimal movement near to sub-nm. In this study a modularized nanopositioner based on parallelogram four-bar linkage structure with right-circular flexure hinge was developed. The positioning performance of a single axis nanopositioner and a XY nanopositioner which was extended from single axis one were demonstrated using control experiments. Consequently, it was shown that the developed single axis nanopositioner possessed high performance and could be extended to various multi-axis nanopositioners.

• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1954-1959
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• 2015

Bacillus subtilis HM1 was isolated from the rhizosphere region of halophytes for its antifungal activity against Colletotrichum acutatum, the causative agent of anthracnose. Treatment of postharvest apples with the cell culture or with a cell-free culture supernatant reduced disease severity 80.7% and 69.4%, respectively. Both treatments also exhibited antifungal activity against various phytopathogenic fungi in vitro. The antifungal substances were purified and analyzed by acid precipitation, gel filtration, high-performance liquid chromatography, and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Three compounds were identified as fengycin, iturin, and surfactin. The MALDI-TOF/TOF mass spectrum revealed the presence of cyclized fengycin homologs A and B, which were distinguishable on the basis of the presence of either alanine or valine, respectively, at position 6 of the peptide sequence. In addition, the cyclized structure of fengycin was shown to play a critical role in antifungal activity.

• Journal of the Korean Arthroscopy Society
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• v.2 no.1
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• pp.40-44
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• 1998

The use of autogenous tissues is preferred for knee ligament reconstruction. However allografts play a role in major ligament reconstructive procedures in which multiple substitutions or revisions are required. In the dislocated knee, allografts may offer an advantage in reconstructing the PCL. But allografts in knee ligament surgery must be considered in terms of biomechanical and regenerative properties, disease transmission and immunogenecity, and methods of preservation and sterilization. Also only a few authors have described the use of allograft for reconstruction of a ruptured PCL, either a single procedure, or in combination with ACL repair following knee dislocation. Furthermore, the problems that the clinician faces with use of allografts is the necessity for supervision to ensure that the grafts are correctly processed, secondarily sterilized, and free of transmissible diseases. For these reasons, the routine use of allograft materials in the treatment of ligament deficiencies should be avoid and provide with meaningful outcome studies, including longterm follow-up.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.293.3-294
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• 2002

In the brain, glial cells serve in the role to sequester metal from the neural microenvironment and therefore play an important role as a cellular deposition site. The central nervous system is highly vulnerable to oxidative stress, and free iron can stimulate oxidative stress by the Fenton reaction. Aluminum may upregulates the transferrin-independent iron uptake system and stimulate oxidative stress. Nramp2. also known as DMT 1. is a 12-transmembrane(TM) domain protein responsible for dietary iron uptake as well as metal ions such as iron. lead, mangamese. zinc. copper, and cobait. (omitted)

• Korean Journal of Child Studies
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• v.22 no.1
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• pp.213-226
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• 2001

In this study of intentions and strategies of children's requests and teachers' responses, the subjects were 20 teachers and 610 4- and 5-year-old children in 10 kindergartens. Each teacher wore an audio-recorder and one-to-one interactions between teacher and child were audiotaped during a 40-minute free play session. Children made requests most frequently with the intention of getting attention; they also made requests for the purpose of seeking information. In making requests, children utilized various strategies including direct, indirect, and physical strategies. Furthermore, their strategies were dependent on intention. Teachers most frequently responded to children with the strategy of committed compliance. Results were discussed in terms of roles of active children and responsive teachers in forming and maintaining good teacher-child relationships.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.737-740
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• 2000

Two groups of bacteria, harmful and useful bacteria, coexist in our body. Harmful bacteria and free radicals which cause many diseases and agings could be controlled by not synthetic materials but natural products. 50 kinds of natural products were searched for this purpose, some of them expressed bacterial controlling ability. Clostridium difficle was controlled by Paeonia Japonica and Lycii Fructus, etc., Clostridium perfringens was inhibited by Scutellaria Baicalensis and Astragali Radix, etc., and same way, Listeria monocytogenes; Paeonia Japonica and Scutellaria Baicalensis, E. coli; Scutellaria Baicalensis and Schizandrae Fructus, Staphylococcus aureus; Paeonla Japonica and Scutellaria Baicalensis, Streptococcus mutans; Coptis Rhizoma, respectively. These natural products will play an important role in bio-Industry.

• International Commerce and Information Review
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• v.9 no.1
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• pp.333-353
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• 2007

This paper is to explore that there are structural problems in the Korea-U.S. Free Trade Agrement negotiation by examining the Korean FTA policy and to introduce some alternatives to overcome them. The structural problem stems in part from the inefficient system in FTA policy making and its implementation. Most importantly, there is a lack of ex-ante consensus building among stake-holders. As an alternative to the current FTA policy, we suggest two things. First, we argue that an FTA negotiation strategy should correspond to Korea's overall industrial development strategy. Second, the National Assembly should play an important part for enforce of trade policies as a tool for advancing a comprehensive strategic measures.

• Korean Journal of Child Studies
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• v.22 no.4
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• pp.201-212
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• 2001

The purpose of this study was to analyze toddlers' verbal and nonverbal interaction with their peers and caregivers according to the class size of child care centers in Seoul. The subjects of this study were 20, two-year-old(M=32.5 month) toddlers with peers and caregivers from child care centers in different class sizes, but with same caregiver-toddler ratio. Verbal and nonverbal interactions were videotaped during one hour indoor free play per child in the center. According to the class size, the results were as follows : 1) Toddlers in the small class played more cooperatively with peers, and uttered more regulative or directive words than those in the large class. 2) Toddlers in the large class were more aggressive than those in the small class. 3) Caregivers in small class expressed more empathetic behaviors to a toddler than those in large class.