• YAKHAK HOEJI
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• 제39권4호
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• pp.444-449
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• 1995

Primary cultures of rat cortical and chicken embryonic brain cells were employed to establish a reliable screening method for natural products blocldng or enhancing glutamate-induced neurotoxicity. Exposure of primary cultured rat cortical cells or chicken embryonic brain cells to high dose of glutamate resulted in the fragmentation of neutites and consequent neuronal death. The level of cytoplasmic lactate dehydrogenase(LDH), indicator for cell survival in cultures, was significantly reduced at exposure to glutamate. For the practical application of the methods, series of concentrations of plants extracts and positive control were applied prior to the glutamate insult on primary cultures of rat cortical and chicken embryonic, brain cells. Relative LDH level in cells was measured for the estimation of the effect of the test materials on the glutamatergic neurons. The validity of the present screening method for natural products acting on glutamatergic neurons was examined with dextromethorphan, a known glutamatergic antagonist. The treatment of 100 $\mu{M}$ dextromethorphan prevented the reduction of LDH in rat cortical and chicken embryonic brain cells caused by glutamate insult keeping 60% and 90% of LDH level in normal control, respectively. Above results indicate that primary cultures of rat cortical and chicken embryonic brain cells could be proper systems for the screening of potential natural agents acting on glutamatergic, neurons. Between the two types of cultures, primary culture of chicken embryonic brain cells seemed to be a better system for the primary screening, since it is technically easier and economical compared to that of rat cortical cells.

• Research in Mathematical Education
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• 제18권4호
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• pp.257-272
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• 2014

This paper examines and presents descriptions of 12 prospective primary teachers' views on the nature of mathematics in USA. All the participants were elementary teacher candidates enrolled in the same mathematics method courses. Interview data show that the prospective primary teachers possess two kinds of views on the nature of mathematics: primarily traditional and even mix of traditional and nontraditional beliefs in terms of Raymond's (1997) belief criteria. Implications for teacher education were discussed at the end of the paper.

• Korean Journal of Mathematics
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• 제22권2호
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• pp.289-305
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• 2014

In this paper we propose a new approach to the variable selection problem for a primary resolution and wavelet basis functions in wavelet regression. Most wavelet shrinkage methods focus on thresholding the wavelet coefficients, given a primary resolution which is usually determined by the sample size. However, both a primary resolution and the basis functions are affected by the shape of an unknown function rather than the sample size. Unlike existing methods, our method does not depend on the sample size and also takes into account the shape of the unknown function.

• Nuclear Engineering and Technology
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• 제56권4호
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• pp.1250-1253
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• 2024

Activity measurement of the primary circuit water of fission reactors is one method that can provide early detection of a damaged fuel assembly in the reactor core. This is an important aspect in the safe operation of the reactor and for radiation protection of staff. Radionuclides in the primary circuit water are produced by the activation of stable nuclides and the fission of fissile nuclides, mainly the isotope ²³⁵U. In the LVR-15 research reactor, measurement of the activity of the primary circuit water has been regularly undertaken since 1996. A water sample is taken from the primary circuit every week and the activities are measured four days later using gamma spectrometry. The results of these long-term measurements from 1996 to 2022 are presented. The activity time dependences of the individual radionuclides are discussed in relation to fuel assembly damage and for events connected to contamination of the water by objects inserted into the primary circuit during experiments carried out near the reactor core.

• Korean Journal of Medicinal Crop Science
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• 제21권4호
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• pp.276-281
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• 2013

This study was conducted to compare the contents of ginsenoside according the water extract conditions of red ginseng. In method A, red ginseng extract was prepared at $75^{\circ}C$ for 18 hours by 1 time extraction, and method B, the preparation was done at $85^{\circ}C$ for 18 hours by 1 time extraction. In method C, the primary extract prepared at $75^{\circ}C$ for 9 hours was blended with the secondary extract prepared by re-extracting the red ginseng residue obtained after the primary extraction, at $85^{\circ}C$ for 9 hours. Method D was the same procedure as method C but the extraction temperature for the primary extraction was $85^{\circ}C$ and that for the secondary extraction was $95^{\circ}C$. The contents of total and $Rb_1$, $Rg_1$ and $Rg_3$ ginsenoside were highest in Method C. The content of prosapogenin (ginsenoside $Rg_2$, $Rg_3$, $Rb_1$ and $Rb_2$) was highest in Method B. There was no consistent tendency in Brix, pH, Hue value and absorbance among extraction methods.

• Journal of KSNVE
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• 제8권3호
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• pp.513-523
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• 1998

Impact response of a vibro-impact system and its contact mechanism was studied. The vibro-impact system is composed of a small secondary system is constrained to move along a slot of fixed length in a large primary system. The contact mechanism is characterized by its coefficient of restitution. Numerical simulation analysis has been used to determine the time-history and the impact statistics of the primary and secondary systems. Input excitation of the primary system was random, and the responses obtained were the velocities of the primary and secondary system, the closing velocity in time axis and the duration time between impacts. The validity of the numerical simulation method was checked by comparing the results with those obtained by other researchers analytically. It is shown that the results obtained by the nemerical simulation analysis showed a good agreement with those for the analytical method.

• The Transactions of the Korean Institute of Power Electronics
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• 제17권5호
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• pp.445-452
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• 2012

The impurity detection method applied to existing discriminated the normality(R, L, C) and impurity(Metal) load using mutual RFID/ID method in the contactless power supply in which the primary side and the secondary side are completely separation by using the contactless transformer. However, this kind of system is caused the high cost of the system and complexity of control. Therefore, in this paper was proposed the contact-less power transfer using the primary current that determine normality or impurity load by compare the primary current Amplitude to reference quantity value and design the 3[W] contact-less power transfer and conduct an experiment for demonstrate the validity.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(2)
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• pp.176-179
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• 2000

Fault simulation is often necessary to determine the fault coverage of a given test, that is, to find all the faults detected by test. In this paper we implement a deductive fault simulation using counting method. Counting method uses f$\sub$ｉ/ of fault table and Search list to compute set operation. f$\sub$ｉ/ was counted by fault list of input gate. And we propagate fault list from primary inputs toward primary output by comparing with controling sum. It improved performance by reducing search of faults.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1990년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 26-27 Oct. 1990
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• pp.1410-1414
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• 1990

A method of speed sensorless vector control of induction motor is proposed in this paper. This method uses the slip frequency estimated by only the primary voltage and current. As this slip frequency accords with the command value of it, the commanded primary frequency is controlled. The validity of the method is confirmed by the simulation and experimental results.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.342-349
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• 2008

A selection method of primary degrees of freedom in dynamic condensation for nonproportional damping structures is proposed. Recently, many dynamic condensation schemes for complex eigenanalysis have been applied to reduce the number of degrees of freedom. Among them, iterative scheme is widely used because accurate eigenproperties can be obtained by updating the transformation matrix in every iteration. However, a number of iteration to enhance the accuracy of the eigensolutions may have a possibility to make the computation cost expensive. This burden can be alleviated by applying properly selected primary degrees of freedom. In this study, which method for selection of primary degrees of freedom is best fit for the iterative dynamic condensation scheme is presented through the results of a numerical experiment. The results of eigenanalysis of the proposed method is also compared to those of other selection schemes to discuss a computational effectiveness.