• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.184.2-184.2
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• 2013

대기압 플라즈마와 생체용액과의 상호작용은 Bio-medical 분야에서 주목 받고 있다. 대기압 플라즈마는 전자온도가 고온 플라즈마 보다 상대적으로 낮기 때문에 생체에 적용하기가 적합하다. 따라서 플라즈마가 세포에 미치는 영향을 관측하기 위해서 대기압 플라즈마를 이용하여 생체용액과의 반응을 살펴보고자 한다. Ar gas를 이용하여 플라즈마를 발생시켜 생체용액 표면을 처리하고 OES (Optical Emission Spectroscopy)을 이용해 방출 선을 조사했다. Ar 기체를 이용한 대기압 플라즈마를 사용하여 다른종류의 용액내의 OH Radical Density를 측정하였다. 용액으로는 DI (deionized) water 와 PBS (1x phosphate buffered saline)를 사용하였다. Ar gas를 200 sccm ($cm^3/min$) 으로 흐르게 하였을 때, DI water의 OH Radical Density 는 $4.33{\times}10^{16}cm^{-3}$ 으로 측정되었으며, 자외선 흡수분광법으로 측정한 완충용액인 PBS의 OH Radical Density 측정값은 $1.87{\times}10^{16}cm^{-3}$ 이다. 이런 특성을 기반으로, PBS 용액내의 H460 (Lung Cancer Cell) 와 L132 (Lung Normal Cell)을 깊이와 시간에 따라 대기압 플라즈마로 처리하여 cell의 변화를 보았다. 실험 각각의 조건은 깊이를 2 mm, 4 mm, 6 mm이며 시간은 10 sec, 30 sec, 60 sec 로 설정하였다. 표면으로부터의 깊이가 2 mm, 4 mm, 6 mm 일때 의 OH Radical Density는 각각 $1.87{\times}10^{16}cm^{-3}$, $0.5{\times}10^{16}cm^{-3}$, 0으로써 용액이 깊어질수록 OH Radical Density가 감소함을 볼 수 있다. OH radical density가 높은 2 mm 에서, 처리한 시간이 길어질수록 Cell 은 영향을 많이 받음을 관찰 할 수 있었다. H460 이 L132 보다 플라즈마에 영향을 많이 받음을 확인하였다. 특성변화를 알아보기 위하여 raman spectroscopy, flow cytometry, electron spin resonance로 측정한다.

• Applied Microscopy
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• v.11 no.1
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• pp.59-65
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• 1981

The pars distalis of the Korean frogs (Rana dybowskii Guenther) during hibernating and active periods was observed with the electron microscope. Seven cell types were classified according to the size and shape of secretory granules and to the ultrastructural characteristics. There were many differences between hibernating and active frogs in type 5 cells. Therefore the following results were observed. Cell type 1; This type cell contains spherical secretory granules, $375{\sim}687m{\mu}$ in diameter. Cell type 2; This type cell contains various secretory granules, $250{\sim}437m{\mu}$ in diameter Cell type 3; Spherical and rod-shaped granules, $l25{\sim}187m{\mu}$ in diameter were observed. Cell type 4; In this type cell, the electron density is the lowest and the density of granules is the highest of all type cells. This type cell contains various secretory granules and large secretory granules, $2l0{\sim}420m{\mu}$ in diameter, were also observed. Cell type 5; The electron density of this cells is similar to that of type 4 cells. The density of granules is lower than that of type 4 cells. And the shapes of the secretory granules are similar to those of type 4 cells. But many rod shaped granules, $200{\sim}863m{\mu}$ in diameter, were also observed. Cell type 6; This type was similar to type 2. The electron density of cytoplasm is very low. Spherical granules, $232{\sim}316m{\mu}$ in diameter, were observed. Cell type 7; This type of cell has no secretory granules. This cell is not developed very well. The type 5 cells in hibernating frogs are different from cells in active frogs. In type 5 cells, many secretory granules were observed during active period. But the number of secretory granules were greatly declined and there were many vacuoles in cytoplasm during hibernating period.

• KSBB Journal
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• v.9 no.5
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• pp.457-463
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• 1994

A new method that considers the pellet sedimentation characteristics for fungal cell concentration measurement was developed using optical density. Appropriate mixing of the pellet suspension almost homogeneously was tried to prevent the sedimentation of the pellet by a small magnetic bar in cuvette, giving a stable optical density. The linear relationship between optical density and the dry cell weight was obtained. However, different curved lines were observed according to the pellet size. Optical density couldn't be detectable in the size range of $355{\mu}m$above. It was concluded from the result that the use of optical density for measuring cell concentration in fungal broth became possible by considering the characteristics.

• Solar Energy
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• v.8 no.2
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• pp.12-18
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• 1988

The effect of surface recombination current density on the saturation current density in Si solar cell has been studied. Theoretical model for surface recombination current was set up from emitter transparent model of M.A. Shibib, and saturation current of Si solar cell made by ion implantation method was also measured by digital electrometer. The theoretical surface recombination current density which is the same as saturation surface recombination current density in Shibib model was $10^{-11}[A/cm^2]$ and the measured value was ranged from $8{\times}10^{-10}$ to $2{\times}10^{-9}[A/cm^2]$. Comparing with the ideal p-n junction of Shockley, transparent emitter model shows improved result by $10^2$ order of saturation current density. But there still exists $10^2$ order of difference of saturation current density between theoretical and actual values, which are assumed to be caused by 1) leakage current through solar cell edge, 2) recombination of carriers in the depletion layer, 3) the series resistance effect and 4) the tunneling of carriers between states in the band gap.

• Journal of the Korean institute of surface engineering
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• v.27 no.6
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• pp.340-346
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• 1994

The method of uniforming current distribution in Hull cell are studied by using auxiliary anode, current shield bipolar electrode, and combinings bipolar electrode with current shield in order to find a way of uni-form deposition. The current density distributions are measured by each ammeter of the same inner resistance connected to divided cathode pannel respectively. The current density distributions of cathode electrode divided into five sections with 5mm width have a tendency of linear inclination, and that of twenty sections have a tendency of smoother curve than the curve of original Hull cell pannel. Their results showed lower value on the high current density portion and higher value on the low portion than that original Hull cell pannel. The current distribution in Hull cell is able to unify by using auxiliary anode, or combining bipo-lar electrode with current shield, but not efficient in using one of both individually.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.6
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• pp.713-717
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• 1998

The synergistic effect of fetal calf serum (FCS) and chicken embryo extract (CEE) on protein synthesis of chicken embryo myoblasts was examined. Myoblasts were derived from chicken embryo cultured for 14 days by trypsin digestion and cultured in 5% $CO^2/95%$ air at $37^{\circ}C$. When myoblasts were cultured at the low level of cell density (20-50% of well), CEE enhanced the ability of FCS to stimulate protein synthesis of myoblasts. However, there was no significant effect of CEE to stimulate protein synthesis of myoblasts cultured at high level of cell density (100% of well).

• ETRI Journal
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• v.39 no.6
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• pp.859-865
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• 2017

This paper presents a method for determining the optimum active-area width (OAW) of solar cells in a module architecture. The current density-voltage curve of a reference cell with a narrow active-area width is used to reproduce the current density profile in the test cell whose active area width is to be optimized. We obtained self-consistent current density and electric potential profiles from iterative calculations of both properties, considering the distributed resistance of the contact layers. Further, we determined the OAW that yields the maximum efficiency by calculating efficiency as a function of the active-area width. The proposed method can be applied to the design of the active area of a dye-sensitized solar cell in Z-type series connection modules for indoor and building-integrated photovoltaic systems. Our calculations predicted that OAW increases as the sheet resistances of the contact layers and the intensity of light decrease.

• 한국전산유체공학회:학술대회논문집
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• 2003.08a
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• pp.219-224
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• 2003

An analysis procedure for the MCFC channel flow has been developed to predict the fuel cell performance. As for the electrochemical reaction, among several chemical reaction models, one that fits the data best is adopted after a comprehensive comparative study. The Wavier-Stokes, energy, and species equations are solved to obtain the velocity, temperature and concentration fields for a specified average current density. The procedure is iterative as the local current density, or the reaction rate, is allowed to vary with the gas composition. A series of calculations are then carried out to examine the effects of gas flow rate, gas composition, gas usage rate, inlet gas temperature, and average current density on the fuel cell performance. The fuel cell characteristics, such as the temperature, current density distributions, and the concentration fields, for various operating conditions are presented and discussed.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.357-360
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• 2009

The present study focused on the segmented cell which has the similar performance to unaltered (not segmented) cell in real operating condition. Many literatures have been made the segmented cell to observe the behavior of local current density distribution in the single cell. However, it has been lack of scheme to segment the cell in that the detailed interpretation of segmenting in analytic point of view was insufficient. Hence, the basic idea of segmenting was introduced to determine the component to be segmented in anode side of unit cell. The electrical contact/bulk resistance was measured by using four wire/probe method through each part of cell components including MEA, GDL, Bipolar Plate and Current Collector. Electron transport mechanism was predicted by comparing resistance values which were obtained from the experiment. As a result, this offered a great benefit to segment the cell efficiently. With this method further experiments would be conducted in research areas which require current density distribution at the same operating condition as unaltered cell.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.3
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• pp.254-261
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• 2005

The over-expression of Bcl-2 has greatly improved the culture period, specific growth rate, and maximum viable cell density of NS0 cells culture under low serum condition. Further analysis of these data suggests that a saturation model of the Monod type can be used to represent the relationships of specific growth rate and initial serum concentration. The ${\mu}_{max}$ and $K_s$ for the Bcl-2 cell line is $0.927day^{-1}\;and\;0.947\%(v/v)$ respectively, which are $21\%$ greate and $7\%$ lower respectively than its control counterpart. Study on the amino acid supplementation revealed that Bcl-2 cell lines possess greater improvement in the specific growth rate and maximum viable cell density compared to the control cell lines. A further increase in the amino acid supplementation has resulted a $17\%$ decrease in specific growth rate and no improvement in maximum viable cell density in the control culture. However, the Bcl-2 cell line exhibited a better growth characteristic in this culture condition compared to that of control cell lines. The higher specific growth rate and maximum viable cell density of the Bcl-2 cell line in medium fortified with serum and MEM EM suggested a more efficient nutrient metabolism compared to that in the control cell line. The low serum and amino acid utilisation rate and the higher cell yield may prove to be important in the development of serum/protein free culture.