• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.6-10
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• 2016

Until a recent day, degradation of PEMFC (Proton Exchange Membrane Fuel Cells) has been mainly studied in unit cell. But operation and degradation of real PEMFC going along in stack instead of unit cell. Therefore in this work, ADT (Accelerated Degradation Test) of PEMFC was done in stack and the result from stack's test was compared with that of unit cell. The polymer electrolyte membrane was degraded by repeated electrochemical and mechanical degradation method among several ADT methods. Current densities of MEA at 0.6V decreased in stack and unit cell, 28.4% and 27.8% respectively after ADT for 312 hours. Hydrogen crossover current densities of membrane increased in stack and unit cell, 16.8% and 15.2% respectively after ADT for 312 hours. The result of ADT in stack was similar that of ADT in unit cell, which showed that ADT method of unit cell was available to the stack.

• Journal of the Korean Data and Information Science Society
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• v.14 no.2
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• pp.303-311
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• 2003

We consider the problem of testing cell probabilities in sparse multinomial data. Aerts, et al.(2000) presented $T_1=\sum\limits_{i=1}^k(\hat{p}_i-p_i)^2$ as a test statistic with the local polynomial estimator $(\hat{p}_i$, and showed its asymptotic distribution. When there are cell probabilities with relatively much different sizes, the same contribution of the difference between the estimator and the hypothetical probability at each cell in their test statistic would not be proper to measure the total goodness-of-fit. We consider a Pearson type of goodness-of-fit test statistic, $T=\sum\limits_{i=1}^k(\hat{p}_i-p_i)^2/p_i$ instead, and show it follows an asymptotic normal distribution.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.11a
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• pp.369-376
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• 2000

Parameters that represent the characteristic of consolidation have been determined by the oedometer tests. They are varied by the process of sampling and transportation, accuracy of apparatus, process of sample trimming and the skill of engineers. Also, it is difficult to grasp what factor exert a influence on the parameters. In this study, Slurry Rowe Cell Tests were peformed to evaluate the disturbance. Using the plot of e - log p which obtained from Rowe Cell test results, we compared the swelling indexes at the stress relief and the last loading stage. With that result, we tried to presume the disturbance of the 330 oedometer tests. The plot of compression-swelling index at the stress relief considerably scattered but at the last step of load shows a correlations between them. And the plot of depth-p$\sub$c/ shows a correlation with the different swelling indexes, but not in the LL-p$\sub$c/. Consequently, it is considered that the disturbance of the consolidation tests can be presumed by the comparison of the difference of swelling index.

• Proceedings of the Korean Geotechical Society Conference
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• 1997.10a
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• pp.57-64
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• 1997

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.1225-1226
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• 2012

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.315-315
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• 2005

• Proceedings of the Korean Nuclear Society Conference
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• 2001.10a
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• pp.137.2-137
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• 2001

• Korean Journal of Plant Resources
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• v.4 no.1
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• pp.17-22
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• 1991

Codonopsis lanceolata and C.pilosula medicinal plants were subjected to preliminary antitumor screening test with Sarcoma 180 ascites and screning on V-79 cell. This ex-periments Iwere conducted in accordance with the Total packed cell Volume methodand Cytotoxicity method .

• Analytical Science and Technology
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• v.34 no.6
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• pp.275-283
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• 2021

This study presents the development of cell-based microfluidic chips for the performance of acute eye irritation tests due to chemicals and examined some of their applications. Microfluidic chips were fabricated by photolithography and soft lithography, and they had three compartments with different areas for cell culture. Rabbit corneal epithelial cells were used for the eye irritation test. The death of cells cultured inside the chip was monitored at regular time intervals after treatment with an aqueous solution of chemicals, and the cell death rate constants were calculated based on the viability curve. The performance of the microfluidic chip was verified by examining the effects of cell-cell junctions, cell-substrate adhesion, and initial cell numbers compared to cell death rates. Eye irritation tests were performed at various concentrations of an aqueous solution of sodium dodecyl sulfate (SDS), a standard substance for the eye irritant test. The cells were exposed to the SDS aqueous solution for 300 s, and the resulting eye irritation was assessed by cell viability. Finally, the equation for calculating the toxicity score (TS) was derived based on the weighting factor for each compartment in the chip. The cell-based microfluidic chip developed in this study may be used for eye irritation tests from chemicals used in cosmetics and pharmaceuticals.

• KIEE International Transactions on Electrophysics and Applications
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• v.4C no.4
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• pp.176-180
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• 2004

This paper presents the fabrication and test of a micro cell exciter actuated by an electromagnetic force for the study on the chondrogenic differentiation of rabbit mesenchymal stem cells (MSCs). The micro cell exciter is designed to apply compressive loading to the alginate gel mixed with the MSCs. The magnetic cell exciter consists of an actuator component and a cartridge-type chamber component. An actuator is composed of a permanent magnet, a core and a coil. The chamber has seven PMMA wells and a cell culture Petri dish. Two types of alginate gels were stimulated by the cell exciters for 10 minutes every 12 hours for 7 days. In order to determine the expression of these matrix components during differentiation, RT-PCR analysis was performed. Collagen type II was expressed in the MSCs subjected to the compressive stimulation.