• 대한의생명과학회지
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• 제20권3호
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• pp.147-155
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• 2014

It has well studied that immune cells are strongly related to tumor progression and tumor suppression. To identify the difference of immune cell between tumor bearing mice and normal mice, we examined systemically the immune cell of CT26 tumor bearing mice on 21 days after tumor cell administration. As previously reported, CD4+ and CD8+ T cells population of tumor bearing mice significantly decreased 38% and 30% on day 21 compared to that of normal mice, respectively. All subpopulation of CD4 and CD8+ T cell significantly decreased, except CD49b+ T cell subpopulation. But, myeloid cell population ($CD11b^{high}$ and all Gr-1+ subpopulation) of tumor bearing mice significantly increased on day 21. Especially, all subpopulation of CD11b+Gr-1+ cell of tumor bearing mice significantly increased on day 21. Also, Foxp3+$CD25^{high}$ CD4 T cell (regulatory T cells) population significantly increased on day 21. These results suggest that tumor can induce the decline of T lymphocyte and the expansion of myeloid cells and regulatory T cells, and provide the basic information for the study of tumor immunology.

• 한국수정란이식학회지
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• 제33권1호
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• pp.41-48
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• 2018

In the last several decades, cell therapy research has increased worldwide. Many studies have been conducted on cell therapy, and have revealed that transplanted cells did not survive for long, and implanted cells remained inactive causing immune rejection depending on the patient's condition. Therefore, studies on cell-free therapy need to be conducted. To overcome these limitations, an alternative is the use of supernatant from cells, called "conditioned media (CM)." During in vitro cell culture, culture media supply nutrients to maintain cell characteristics and viability. In the culture, cells not only consume nutrients but also release beneficial proteins and substances, which are called "secretome." CM from cells can be stored for a long time and is easy to handle. Moreover, secretome in CM can also be measured; exact amount of secretome is important to set the standard value for disease treatment. Here, we reviewed studies on CM and confirmed that various secretomes from CM were identified in these studies. Moreover, these findings could benefit cell and animal studies in future. In conclusion, CM could be a potential candidate for an alternative to cell therapy.

• 대한한의학회지
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• 제21권3호
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• pp.140-148
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• 2000

Objectives : This experiment was conducted to investigate the suppressive effects of Dangguijakyak-san and Wuelbigachul-tang on the expression of ICAM-l and ${\beta}1-integrin$, which mediate cell-cell or cell-matrix interaction, and on the proliferation of mesangial cells. Methods : After in vitro culturing of human mesangial cells with the supernatant which was obtained from the monocytes separated from human blood with Con-A, hydrocortisone, Dangguijakyak-san and Wuelbigachul-tang respectively, we evaluated suppressive effects by measuring the mesangial cell surface enzyme immunoassay or flow cytometry. Results : The results are summarized as follows: 1. Dangguijakyak-san and Wuelbigachul-tang induced marked suppressive effects on the mesangial cell proliferation in the 50% and 25% supernatant concentration stimulating experiments, but hydrocortisone had little effect in these experiments. 2. Dangguijakyak-san and Wuelbigachul-tang induced marked suppressive effects on ICAM-l and ${\beta}1-integrin$ expression, but were less effective than hydrocortisone was. Conclusions : Based on these results, Dangguijakyak-san and Wuelbigachul-tang were found to be effective in the suppression of mesangial cell proliferation and in ICAM-1 and ${\beta}1-integrin$ expression. Further in vitro investigations as conducted above, with the in vivo experiments reflected, may prove that Dangguijakyak-san and Wuelbigachul-tang contribute to the prevention of the glomerular disease.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 춘계학술대회
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• pp.326-329
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• 2005

Proton exchange membrane (PEM) should be sufficiently hydrated with proper water management to maintain a good ionic conductivity and performance of a PEM fuel cell. However. cathode flooding resulting from excess water can impede the transport of reactants and hence deteriorate the fuel cell performance. For the PEM fuel cell to be commercially viable as vehicle or portable applications, the flooding on the cathode side should be minimized during the fuel cell operation. In this study, visualization technique was applied to understand the cathode flooding phenomena on the cathode side of a PEM fuel cell. To this end. a transparent PEM unit fuel cell wi th an act ive area of $25cm^2$ was designed and manufactured to allow for the visualization of cathode channel with performance characteristics. Two-phase flow resulting from the electro-chemical reaction of fuel cell was investigated experimentally. The images photographed by CCD camera with cell operating temperatures $(30\~50^{\circ}C)$ were presented. Results indicated that the flooding on the cathode side first occurs near the exit of cathode channel. As the operating temperature of fuel cell increases. it was found that liquid water droplets tend to evaporate easily and it can have an influence on lowering the flooding level. It is expected that this study can effectively contribute to the detailed researches on modeling water transport of an operating PEM fuel cell including two-phase flow phenomena.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 춘계학술대회
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• pp.233-236
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• 2006

In this paper, I try to measure characteristic transmission-reflection by environmental change or solar cell. I keep my eye on the characteristics variation of solar cell as environmental change. As a result, A variation caused by voltage by an effect on the efficiency of solar PV cell. Hence, it is an important variable when a designer plan to make a solar cell.

• 전자공학회논문지A
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• 제32A권11호
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• pp.71-78
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• 1995

Based on the popular 4-transistor SRAM cell, an analytical expression of the minimum cell ratio was derived by modeling the static read operation. By analyzing the relatively simple expression for the minimum cell ratio, which was derived assuming the ideal transistor characteristics, effects of the changes in supply voltage and process parameters on the minimum cell ratio was predicted, and the minimum power supply voltage for read operation was determined. The results were verified by simulations utilizing the suggested simulation method, which is suitable for monitoring the lower limit of supply voltage for proper cell operation. From the analysis, it was shown that the worst condition for cell operation is low temperature and low supply voltage, and that the operation margin can be effectively improved by reducing the threshold voltage of the cell transistors.

• 한국통신학회논문지
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• 제21권6호
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• pp.1576-1586
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• 1996

The subject of this paper is the analysis of a Wire-TEM cell(W-TEM cell) which has an inner wire array rather than a metallic septum;its basic structure is similiar to a NBS TEM cell. To verify improved performances of this W-TEM cell as a standard EM field generator, well-known quasi-static approximations are employed and their resultant ingegral equations are numerically analyzed by moment method. Although the electric field strength of a W-TEM cell is 1.4 dB lower than tht of a NBS TEM cell, the uniformity of EM field patterns in a W-TEM cell is improved. It is also shown that the EM field distortions resulting from loading by the conditing objects under test(loading effects), are decreased considerably. This paper also deals with the investigations about relationship between the EM field distributions and the number of wire composing the inner conductor. Finally, the experimental analysis is performed on the practical model which is built on the basis of the design variables brought out by the theoretical andnumerical analysis.

• KSBB Journal
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• 제13권4호
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• pp.438-443
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• 1998

Effects of various environmental factors on cell size index(FCW/DCW) in Thalictrum rugosum. Lithospermum erythrorhizon and Taxus cuspidata plant cell suspension cultures were investigated. Time course change of cell size index were also observed. In batch cultures, FCW/DCW increased according to the decrease of sugar concentration. For short-term experiment within 24 hr, FCW/DCW value could be reduced significantly by increasing sugar concentration. When an osmoticum such as mannitol was added, FCW/DCW converged to a low value. Therefore, it was confirmed that osmolality of the medium was important in determining cell size or water content of the cells. Inorganic salts or treatment with organic solvent also exhibited some effect on the cell size index. However, pH and centrifugal force did not show any influences. On the other hand, it was found that the addition of Pluronic F-68 reduced FCW/DCW. By combining these results effectively, it may be possible to increase the cell concentration in high density culture to a higher extent.

• BMB Reports
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• 제49권12호
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• pp.655-661
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• 2016

Polymer brush is a soft material unit tethered covalently on the surface of scaffolds. It can induce functional and structural modification of a substrate's properties. Such surface coating approach has attracted special attentions in the fields of stem cell biology, tissue engineering, and regenerative medicine due to facile fabrication, usability of various polymers, extracellular matrix (ECM)-like structural features, and in vivo stability. Here, we summarized polymer brush-based grafting approaches comparing self-assembled monolayer (SAM)-based coating method, in addition to physico-chemical characterization techniques for surfaces such as wettability, stiffness/elasticity, roughness, and chemical composition that can affect cell adhesion, differentiation, and proliferation. We also reviewed recent advancements in cell biological applications of polymer brushes by focusing on stem cell differentiation and 3D supports/implants for tissue formation. Understanding cell behaviors on polymer brushes in the scale of nanometer length can contribute to systematic understandings of cellular responses at the interface of polymers and scaffolds and their simultaneous effects on cell behaviors for promising platform designs.

• 대한한의학회지
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• 제30권6호
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• pp.17-26
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• 2009

Objectives: Little information is available regarding the effect of Lycii cortex radicis (LCR) on cell viability in glioma cells. This study was therefore undertaken to examine the effect of LCR on cell survival in U87MG human glioma cells. Methods: Cell viability and cell death were estimated by MTT assay and trypan blue exclusion assay, respectively. Reactive oxygen species (ROS) generation was measured using the fluorescence probe DCFH-DA. Activation of Akt and extracellular signal-regulated kinase (ERK) and activation of caspase-3 were estimated by Western blot analysis. Results: LCR resulted in apoptotic cell death in a dose- and time-dependent manner. LCR increased reactive oxygen species (ROS) generation and LCR-induced cell death was also prevented by antioxidants, suggesting that ROS generation played a critical role in LCR-induced cell death. Western blot analysis showed that LCR treatment caused down-regulation of Akt and ERK. The LCR-induced cell death was increased by the inhibitors of Akt and ERK. Activation of caspase-3 was stimulated by LCR and caspase inhibitors prevented the LCR-induced cell death. Conclusion: These findings suggest that LCR results in human glioma cell death through a mechanism involving ROS generation, down-regulation of Akt and ERK, and caspase activation.