• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.876-879
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• 2002

The paper presents the analysis and results of traffic measurements in the 155 Mbit/s real working ATM backbone network. The traffic is described as an ordered sequence of real-time cells. In this paper we analyze two timescales in which some form of a stochastic process is taking place: cell scale and burst scale. We present another way to describe the cell flow in ATM networks by definition the function, designed to be the probability of the burst of length ∫in n sequential slots.

• Journal of Korean Neurosurgical Society
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• v.64 no.3
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• pp.346-358
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• 2021

Secondary neurulation is a morphological process described since the second half of the 19th century; it accounts for the formation of the caudal spinal cord in mammals including humans. A similar process takes place in birds. This form of neurulation is caused by the growth of the tail bud region, the most caudal axial region of the embryo. Experimental work in different animal species leads to questioning dogmas widely disseminated in the medical literature. Thus, it is clearly established that the tail bud is not a mass of undifferentiated pluripotent cells but is made up of a juxtaposition of territories whose fate is different. The lumens of the two tubes generated by the two modes of neurulation are continuous. There seem to be multiple cavities in the human embryo, but discrepancies exist according to the authors. Finally, the tissues that generate the secondary neural tube are initially located in the most superficial layer of the embryo. These cells must undergo internalization to generate the secondary neurectoderm. A defect in internalization could lead to an open neural tube defect that contradicts the dogma that a secondary neurulation defect is closed by definition.

• Archives of Plastic Surgery
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• v.38 no.4
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• pp.438-444
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• 2011

Purpose: Adipose-derived stromal cells (ASCs) are readily harvested from lipoaspirated tissue or subcutaneous adipose tissue fragments. The stromal vascular fraction (SVF) is a heterogeneous set of cell populations that surround and support adipose tissue, which includes the stromal cells, ASCs, that have the ability to differentiate into cells of several lineages and contains cells from the microvasculature. The mechanisms that drive the ASCs into the osteoblast lineage are still not clear, but the process has been more extensively studied in bone marrow stromal cells. The purpose of this study was to investigate the osteogenic capacity of adipose derived SVF cells and evaluate bone formation following implantation of SVF cells into the bone defect of human phalanx. Methods: Case 1 a 43-year-old male was wounded while using a press machine. After first operation, segmental bone defects of the left 3rd and 4th middle phalanx occurred. At first we injected the SVF cells combined with demineralized bone matrix (DBM) to defected 4th middle phalangeal bone lesion. We used P (L/DL)LA [Poly (70L-lactide-co-30DL-lactide) Co Polymer P (L/DL)LA] as a scaffold. Next, we implanted the SVF cells combined with DBM to repair left 3rd middle phalangeal bone defect in sequence. Case 2 was a 25-year-old man with crushing hand injury. Three months after the previous surgery, we implanted the SVF cells combined with DBM to restore right 3rd middle phalangeal bone defect by syringe injection. Radiographic images were taken at follow-up hospital visits and evaluated radiographically by means of computerized analysis of digital images. Results: The phalangeal bone defect was treated with autologous SVF cells isolated and applied in a single operative procedure in combination with DBM. The SVF cells were supported in place with mechanical fixation with a resorbable macroporous sheets acting as a soft tissue barrier. The radiographic appearance of the defect revealed a restoration to average bone density and stable position of pharyngeal bone. Densitometric evaluations for digital X-ray revealed improved bone densities in two cases with pharyngeal bone defects, that is, 65.2% for 4th finger of the case 1, 60.5% for 3rd finger of the case 1 and 60.1% for the case 2. Conclusion: This study demonstrated that adipose derived stromal vascular fraction cells have osteogenic potential in two clinical case studies. Thus, these reports show that cells from the SVF cells have potential in many areas of clinical cell therapy and regenerative medicine, albeit a lot of work is yet to be done.

• BMB Reports
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• v.45 no.3
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• pp.133-140
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• 2012

Cancers claim millions of lives each year. Early detection that can enable a higher chance of cure is of paramount importance to cancer patients. However, diagnostic tools for many forms of tumors have been lacking. Over the last few years, studies of chimeric RNAs as biomarkers have emerged. Numerous reports using bioinformatics and screening methodologies have described more than 30,000 expressed sequence tags (EST) or cDNA sequences as putative chimeric RNAs. While cancer cells have been well known to contain fusion genes derived from chromosomal translocations, rearrangements or deletions, recent studies suggest that trans-splicing in cells may be another source of chimeric RNA production. Unlike cis-splicing, trans-splicing takes place between two pre-mRNA molecules, which are in most cases derived from two different genes, generating a chimeric non-co-linear RNA. It is possible that trans-splicing occurs in normal cells at high frequencies but the resulting chimeric RNAs exist only at low levels. However the levels of certain RNA chimeras may be elevated in cancers, leading to the formation of fusion genes. In light of the fact that chimeric RNAs have been shown to be overrepresented in various tumors, studies of the mechanisms that produce chimeric RNAs and identification of signature RNA chimeras as biomarkers present an opportunity for the development of diagnoses for early tumor detection.

• Biomedical Science Letters
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• v.11 no.1
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• pp.57-61
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• 2005

The number of sites at which a protein can be readily cleaved by a proteolytic enzyme is greatly influenced by its three-dimensional structure. For native, properly-folded proteins both the rate of cleavage and number of sites at which cleavage takes place are usually much less than for the denatured protein. In order to compare the tertiary structure of recombinant HepG2 type glucose transporter with that of its native counterpart in the erythrocyte, the pattern of tryptic cleavage of the protein expressed in insect cell membranes was therefore examined. After 30 minutes digestion, a fragment of approximate Mr 19,000-21,000 was generated. In addition to this, there were two less intensely stained fragments of apparent Mr 28,000 and 17,000. The pattern of labelling was similar up to 2 hours of digestion. However, the fragments of Mr 19,000-21,000 and Mr 17,000 were no longer detectable after 4 hours digestion. The observation of a very similar pattern of fragments yielded by tryptic digestion of the HepG2 type transporter expressed in insect cells suggests that the recombinant protein exhibits a tertiary structure similar if not identical to that of its human counterpart. Also, the endogenous sugar transporter(s) present in Sf21 cells did not bind cytochalasin B, the potent transporter inhibitor. Therefore, the baculovirus/Spodoptera frugiperda (Sf) cell expression system could be very useful for production of large amounts of human glucose transporters, heterologously.

• Journal of Microbiology and Biotechnology
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• v.11 no.6
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• pp.1055-1060
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• 2001

Experimental data for the on-line estimation of cell concentration and growth rate are presented. For this purpose, we utilized the on-line calculation of the oxygen uptake rate (OUR), which was derived from a liquid phase dynamic mass balance for the oxygen during the active growth phase in cyclosporin A (CyA) fermentation. The cell yield coefficient, based on the oxygen $(Y_{x/o})$for both suspended and immobilized cells of Tolypocladium inflatum, was estimated as $1.9 gDCW/gO_2$ from a very good linear correlation between the cell mass produced and the total oxygen consumed. The calculated yield showed a good agreement with the value of $(Y_{x/o})$ generated from the correlation between the cell growth rate and the oxygen uptake rate. In addition, further experimental data are given, which were also applied to determine the specific oxygen uptake rate of T. inflatum cells during the exponential phase of CyA fermentation. A theoretical basis for the analysis of these fermentation parameters is also provided.

• Advances in Energy Research
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• v.4 no.4
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• pp.275-284
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• 2016

In the present work, ZnO nanoparticles (NPs) have been dispersed alone in the same solvent of the active layer for improving performance parameters of the organic solar cells. Different concentrations of the ZnO NPs have been blended inside active layer of the solar cell based on poly(3-hexylthiophene) (P3HT), which forms the hole-transport network, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), which forms the electron-transport network. In the present investigations, the ZnO NPs may represent an efficient tool for improving light harvesting through light scattering inside active layer, electron mobility, and electron acceptance strength which tend to improve photocurrent and performance parameters of the investigated solar cell. The fill factor (FF) of the ZnO-doped solar cell increases nearly 14% compared to the non-doped solar cell when the doping is 50%. The present investigations show that ZnO NPs improve power conversion efficiency of the solar cell from 1.23% to 1.64% with increment around 25% that takes place after incorporation of 40% as a volume ratio of the ZnO NPs inside P3HT:PCBM active layer.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.75-79
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• 2007

The cathode design is one of the most important parts in order to enhance the performance of fuel cells. A 3-D model of the porous oxygen reducing cathode with perforated current collectors is analysed for the enhanced design in fuel cells. Simulation is performed using equations of electric potential balance, momentum balance, and mass balance. The gas concentrations are quite large and are significantly affected by the reactions that take place. The weight fraction of oxygen, velocity field for the gas phase, and local overvoltage are illustrated in the porous reactive cathode layer. The current density is also analysed and the result shows the distribution and variation are stated in a wide range. It is found that the rate of reaction and the current production is higher beneath the orifice, and decreases as the distance to the gas inlet increases. The significance of the results is discussed in the viewpoint of the mass transportation phenomena, which is inferred that the mass transport of reactants dictates the efficiency of the electrode in this design and at these conditions.

• BMB Reports
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• v.45 no.12
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• pp.677-685
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• 2012

In the process of tumorigenesis, normal cells are remodeled to cancer cells and protein expression patterns are changed to those of tumor cells. A newly formed tumor microenvironment elicits the immune system and, as a result, a humoral immune response takes place. Although the tumor antigens are undetectable in sera at the early stage of tumorigenesis, the nature of an antibody amplification response to antigens makes tumor-associated autoantibodies as promising early biomarkers in cancer diagnosis. Moreover, the recent development of proteomic techniques that make neo-epitopes of tumor-associated autoantigens discovered concomitantly has opened a new area of 'immuno-proteomics', which presents tumor-associated autoantibody signatures and confers information to redefine the process of tumorigenesis. In this article, the strategies recently used to identify and validate serum autoantibodies are outlined and tumor-associated antigens suggested until now as diagnostic/prognostic biomarkers in various tumor types are reviewed. Also, the meaning of autoantibody signatures and their clinical utility in personalized medicine are discussed.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3706-3713
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• 1996

A numerical study on natural convection induced by free surface heat flux and cold left and hot right walls in glass melting furnaces has been performed. A function of heat flux derived from the combustion environments of actual glass melting furnace is applied to thermal boundary condition at free surface. Fundamentally there exist two flow cells in cavity (left counterclockwise one and right clockwise one). The effects of heat flux and Rayleigh number are investigated through two-dimensional steady-state assumption. The convection strength of two flow cell located in left region continuously increases. In the mean time the strength of flow cell in right region increases and then decreases. Critical Rayleigh number in which two flow cells take place above and below show linear dependence on the free surface heat flux. To maintain the traditional flow pattern (left and right flow cells) in glass melting furnace, Rayleigh number is recommended to be below 10$^{5}$ .