• Journal of Embryo Transfer
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• v.5 no.2
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• pp.1-10
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• 1990

The individual difference of superovulatory responses and inferior embryo quality in superovulated cattle may cause disturbances in the endocrine profile, follicular steroidogenesis, nuclear maturation of nocyte, fertilization and cleavage of embryos. However, the reasons why those disturbances are occurred were not understood. The methods of the improvement of superovulatory response and embryo production were the use of anti-PMSG if PMSG used, pure FSH or controlled FSH-LH inducer, priming dose of gonadotropin in the first few day of the estrous cycle and GnRH or analogue. However, all of the above methods were not reduced the individual differences but improved embryo production We must continue the fundamental studies to understand the mechanism.

• IE interfaces
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• v.15 no.1
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• pp.99-106
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• 2002

A recently developed alternative to traditional production planning and control systems such as material requirement planning(MRP) and just-in-time(JIT) is the drum-buffer-rope(DBR). The DBR now being implemented in growing number of manufacturing organizations enables better scheduling and decision making on the shop floor. In implementing the DBR, however, an information system is usually needed to transmit the signal that runs from the constraint to material release. In this paper we propose a different mechanism to transmit the signal in the case that the demand of product is stable, which uses the well-known Kanban system. To improve the reality, this paper shows and example of the Kanban format, its operation, and calculation of the number of Kanbans.

• Microbiology and Biotechnology Letters
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• v.32 no.1
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• pp.1-10
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• 2004

Many bacteria monitor their population density and control the expression of specialized gene sets in response to bacterial cell density based on a mechanism referred to as quorum sensing. In all cases, quorum sensing involves the production and detection of extracellular signaling molecules, auto inducers, as which Gram-negative and Gram-positive bacteria use most prevalently acylated homoserine lactones and processed oligo-peptides, respectively. Through quorum-sensing communication circuits, bacteria regulate a diverse array of physiological functions, including virulence, symbiosis, competence, conjugation, antibiotic production, motility, sporulation, and biofilm formation. Many pathogens have evolved quorum-sensing mechanisms to mount population-density-dependent attacks to over-whelm the defense responses of plants, animals, and humans. Since these AHL-mediated signaling mechanisms are widespread and highly conserved in many pathogenic bacteria, the disruption of quorum-sensing system might be an attractive target for novel anti-infective therapy. To control AHL-mediated pathogenicity, several promising strategies to disrupt bacterial quorum sensing have been reported, and several chemicals and enzymes have been also investigated for years. These studies indicate that anti-quorum sensing strategies could be developed as possible alternatives of antibiotics.

• Journal of the Korean Society of Combustion
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• v.15 no.4
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• pp.9-14
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• 2010

Numerical simulations of freely propagating fuel-rich $CH_4/CH_3Cl$ premixed flames were performed at atmospheric pressure in order to understand the effect of the oxygen enrichment on the production of PAH. A chemical kinetic mechanism was used, which involved 157 gas-phase species and 1693 forward reactions. The calculated flame speeds were compared with the experiments for the flames established on the equivalence ratios of 1~1.6, the results of which were in good agreement. As the level of oxygen enrichment was increased, the concentrations of one or four ring aromatic hydrocarbons were decreased. This might cause the fact that the contribution of PAH species to soot was weakened.

• International Journal of Contents
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• v.14 no.3
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• pp.69-74
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• 2018

A new breed of universities equipped with student-centered education programs and advanced digital technologies is changing the face of higher education. "Flipped learning" is heralded as a new model of education, yet its effect is underexplored. The purpose of this study is to provide evaluation criteria to assess and understand the merit of student-centered education programs and apply them to actual cases. Discussion on the nature of knowledge, its production mechanism and system, and possible contribution of digital technology to user-centered programs are discussed to produce five key criteria; initiative of students, interaction in class, interaction in field, customization of courses, and automated personal service. They are applied to evaluation of Minerva and Ecole 42.

• Journal of Plant Biology
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• v.31 no.4
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• pp.267-275
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• 1988

Effects of polyamines on ethylene biosynthesis were studied in synchronized suspension cultured cells from leaf segments of Nicotiana tabacum L. Putrescine, spermidine and spermine inhibited the endogenous production of both ACC and ethylene. Those production was more remarkably inhibited by spermidine and spermine than putrescine. These results were the same tendency with those obtained from exogenous application of SAM and ACC. Polyamines had more inhibitory effect on hte conversion of ACC to ethylene than that of SAM to ACC, but ACC was not accumulated. The inhibition rate of exogenously applied ACC conversion to ethylene was well coincident with that of exogenously applied SAM conversion to ethyene via ACC by polyamines. However, polyamines inhibited more the activity of ACC synthase than that of EFE. From these results we can suggest that polyamines inhibit both steps of SAM to ACC and ACC to ethylene, and more effectively the latter than the former.

• Journal of Plant Biology
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• v.33 no.2
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• pp.87-96
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• 1990

The role of S-adenosylmethionine (SAM) as an intermediate in interrelation between polyamine and ethylene biosynthesis was studied in suspension cultures of Nicotiana tabacum L. Exogenous SAM stimulated the polyamine and ethylene biosynthesis in 4 day-cultured cells, which were in active cell divisions, and 10 day cultured cells, which went on with active cell elongation and senescence. SAM-induced ethylene production was more effective in 10 day-cultured cells than in 4 day-cultured cells, but SAM-induced polyamine biosynthesis was more effective in 4 day-cultured cells than in 10 day-cultured cells. Polyamine contents were increased by the blockage of ethylene biosynthetic pathway in the conversion of SAM to ethylene via 1-aminocyclopropane-1-carboxylinc acid (ACC) with aminooxyacetic acid (AOA). Also, ethylene production was increased by the inhibitors of polyamine biosynthesis such as methylglyoxal bis-(guanylhydrazone) (MGBG), dicyclohexylamine (DCHA), $\alpha$-difluoromethylarginine (DFMA) and $\alpha$-difluoromethylorinithine (DFMO). These results suggest that there may be interrelations between polyamine and ethylene biosynthesis for the competition of SAM and the inherent mechanism of switch on-off in polyamine and ethylene biosynthetic activity with the progress of cell growth and senescence.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.5
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• pp.8-12
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• 2012

Recently, a wide range of industrial production area has a competitive advantage through cost reduction. Moreover with the development of industrial technology, base material and cutting tool help the machining technology. But most of the machining enterprises have not hold the R&D facilities and human resources. This mainly disturbs the industrial development and th increase of production efficiency. Especially in the interrupted machining process, it showed different behavior with continuous machining process. So it needs to research and develop the tool life and tool wear mechanism analysis.

• Biomolecules & Therapeutics
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• v.24 no.6
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• pp.561-571
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• 2016

Marine biosphere is the largest one of the earth and harbors an enormous number of different organisms. Living conditions differ fundamentally from those in terrestrial environment. The production of specific secondary metabolites is an important adaption mechanism of marine organisms to survive in the sea. These metabolites possess biological activities which make them interesting as possible drugs for human. The review presents sources, chemistry, production and pharmacology of FDA approved marine derived pharmaceuticals arranged according to their therapeutic indication. Four of the presently seven approved drugs are used for the treatment of cancer. Each another one is applicated for treatment of viral diseases, chronic pain and to lower triglyceride level in blood. Some other products are of interest in diagnostic and as experimental tools. Besides, this article describes challenges in drug development from marine sources, especially the supply problem.

• Molecules and Cells
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• v.38 no.7
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• pp.597-603
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• 2015

Biosynthesis of the phytohormone ethylene is under tight regulation to satisfy the need for appropriate levels of ethylene in plants in response to exogenous and endogenous stimuli. The enzyme 1-aminocyclopropane-1-carboxylic acid synthase (ACS), which catalyzes the rate-limiting step of ethylene biosynthesis, plays a central role to regulate ethylene production through changes in ACS gene expression levels and the activity of the enzyme. Together with molecular genetic studies suggesting the roles of post-translational modification of the ACS, newly emerging evidence strongly suggests that the regulation of ACS protein stability is an alternative mechanism that controls ethylene production, in addition to the transcriptional regulation of ACS genes. In this review, recent new insight into the regulation of ACS protein turnover is highlighted, with a special focus on the roles of phosphorylation, ubiquitination, and novel components that regulate the turnover of ACS proteins. The prospect of cross-talk between ethylene biosynthesis and other signaling pathways to control turnover of the ACS protein is also considered.