• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.5
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• pp.424-431
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• 2004

An implicit direct-time integration method for obtaining transient responses of general dynamic systems is described. The conventional Newmark method cannot be directly applied to state-space first-order differential equations, which contain no explicit acceleration terms. The method proposed here is the state-space Newmark method that incorporates the average velocity concept, and can be applied to an analysis of general dynamic systems that are expressed by state-space first-order differential equations. It is also readily coded into a program. Stability and accuracy analyses indicate that the method is numerically unconditionally stable like the conventional Newmark method, and has a period error of 2nd-order accuracy for small damping and 4th-order for large damping and an amplitude error of 2nd-order, regardless of damping. In addition, its utility and validity are confirmed by two application examples. The results suggest that the proposed state-space Newmark method based on average velocity be generally applied to the analysis of transient responses of general dynamic systems with a high degree of reliability with respect to stability and accuracy.

• The Research Journal of the Costume Culture
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• v.24 no.1
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• pp.107-113
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• 2016

The purpose of this study was to examine new-silver women's fiber and material property preferences and purchasing behaviors. The survey subjects were 115 new-silver women ranging in age from 50 to 60 years old. This study utilized a questionnaire as a measurement tool. The results of this study were as follows: First, the home ownership rate of the participants in this was 81.4%, and 54.9% of them had a bachelor's degree or higher. Therefore, they turned out to be a new silver generation with higher education and stable income and assets. Second, regarding their purchasing behaviors, it was shown that they purchased the largest amount of clothing for themselves and their spouses, children, and grandchildren at the change of seasons. Third, with regard to their average spending on clothing, when they purchased clothing for themselves, it was shown that they purchased clothing at the price of KRW 500,000 or above for themselves but not for their family members. Fourth, their favorite type of fiber was synthetic fiber, and their favorite material property was heaviness, followed by roughness, stiffness, bulkiness, and glossiness. Moreover, with regard to their favorite functional textile, it was shown that the highest percentage of them preferred vitamin textiles, followed by ocher and scented textiles.

• Korean Journal of Materials Research
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• v.9 no.2
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• pp.217-225
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• 1999

The effect on the pitting corrosion resistance of laser welding and surface treatment developed as a repair method of stream generator tubing material that was a major component of primary system at nuclear power plant was observed. Some heat-treated Alloy 600 tubing materials used at domestic nuclear power plants were laser-surface observed. Some heat-treated Alloy 600 tubing materials used at domestic nuclear power plants were laser-surface melted and the microstructural characteristics were examined. The pitting corrosion resistance was examined through Ep(pitting potential) and degree of pit generation by means of the electrochemical tests and the immersion tests respectively. The pit formation characteristics were investigated through microstructural changes and the pit initiation site and pit morphology. The test results showed that the pitting corrosion resistances was increased in the order of the followings; sensitized Alloy 600, solution annealed alloy600, and laser surface melted Alloy 600. Pits were initiated preferably at Ti-containing inclusions and their surroundings in all tested specimens and it is believed that higher pitting resistance of laser-surface treated Alloy 600 was caused by fine, homogeneous distribution of non-soluble inclusions, the disappearance of grain boundary, and the formation of dense, stable oxide film. The major element of corrosion products filled in the pit was Cr. On the other hand, Fe was enriched in the deposit formed on the pit.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.164-172
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• 1995

The purpose of this electrochemical study was to determine and compare the sealing effect of three commonly used calcium hydroxide-based sealers (Sealapex, Apexit, and CRCS) with that of Roth 801 which is a ZOE-based sealer. 64 single rooted teeth were used in this experiment. After removing the crown, the teeth were devided into 4 groups of 15 in each and obturated with gutta-percha and experimental sealers. 4 teeth were as controls(2 positive and 2 negative). The results were as follows : 1. During the observation period, all sealers showed varying degree of microleakage. 2. The mean leakage currents according to the electrochemical study of each group showed $0.418{\pm}0.006mV$ for Roth 801, $2.03{\pm}0.035mV$ for Sealapex, $3.33{\pm}0.069mV$ for Apxit and $6.48{\pm}0.097mV$ for CRCS group. The positive control group showed 600mV. 3. There were statistically significant difference in mean leakage among experimental groups. ZOE-typed Roth 801 sealer was the lowest, and Sealapex, Apexit, CRCS group in that order showed increased leakage(P<0.05). 4. Roth 801, Sealapex and Apexit group showed increasing leakage with time, but CRCS group showed stable or decreasing leakage tendency.

• Environmental and Resource Economics Review
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• v.13 no.3
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• pp.367-385
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• 2004

This study offers the possibility of water allocation between upstream and downstream regions by side payment. In the case of river water, water use of an upstream region affect a downstream region's water use but not vise versa. In this case, the downstream region wants to secure stable water by suggesting side payment to the upper region. We examine the maximum compensation of the downstream region for acquiring additional water. Also we compare each region's total benefits between the cases with and without cooperation. The result of empirical study show that there was a Pareto improvement when two region cooperate in the water use. Also the amount of side payment depend on the degree of shortage of water and both regions are satisfied with the water allocation result by voluntary negotiation.

• Journal of Microbiology and Biotechnology
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• v.14 no.2
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• pp.350-355
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• 2004

Sulforhodamine B (SRB) assay is a rapid, sensitive, and inexpensive method for measuring cell proliferation and chemosensitivity. However, the lactate dehydrogenase (LDH) release assay is generally used to measure cytototoxicity of infectious microorganisms against host cells. In this study, we investigated the possibility of applying the SRB assay to determine cytotoxicity for infectious microorganisms, and compared the results with those obtained by the LDH release assay. We used Vibrio vulnificus as a model of infectious microorganisms. The SRB assay showed that V vulnificus strongly induced cytotoxic activity against human intestinal cells, Caco-2 and INT-407 cells. The degree of cytotoxicity closely correlated with infection time and number ratios of V. vulnificus to intestinal cells (MOI, multiplicity of infection). Furthermore, cytotoxicity values obtained by SRB assay correlated well with results obtained by the LDH release assay, and both assays gave a linear response with respect to MOI Heat-inactivation of V. vulnificus for 35 min at $60^{\circ}C$ did not induce cytotoxic activity, indicating that viability of V. vulnificus is crucial for cytotoxic activity against intestinal cells. Although both assays are suitable as cytotoxicity endpoints, the SRB assay is recommended for measuring cytotoxicity of infectious microorganisms against host cells because of its significantly lower cost and more stable endpoint than the LDH release assay.

• Journal of Microbiology and Biotechnology
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• v.12 no.5
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• pp.735-739
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• 2002

Large quantities of porcine hepatocyte aggregates with various degrees of aggregation (DA) could be obtained by controlling the suspension periods (0,9,24, and 48 h), and by entrapping the hepatocyte aggregates in model materials of encapsulation such as Ca-alginate and type-I collagen gels. The effects of DA on liver-specific functions of hepatocytes were evaluated in order to obtain optimum DA for the cell source of bioartificial liver (BAL) systems. Irregular rugged aggregates (size $75 \pm 28$ $\mu\textrm{m}$) farmed by 24 h of suspension culturing showed peak viability and hepatic functions such as ammonia removal and albumin secretion in the two types of entrapment systems, thus offering themselves as a stable cell source of a BAL system for hepatic functions and scale-up.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.2
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• pp.224-230
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• 2008

This paper is concerned with the active vibration control of building structure by means of the active tuned mass damper and the modified positive position feedback controller. To this end, one-degree-of-freedom spring-mass-damper system equipped with ATMD is considered. The stability condition for the addressed system when applying the proposed PPF controller is derived by Routh-Hurwitz stability criterion. The stability condition shows that the modified PPF controller is absolutely stable if the controller gain is positive. so that the modified PPF controller can be used without difficulty. Theoretical study shows that the modified PPF controller can effectively suppress vibrations as the original PPF controller does in smart structure applications. To investigate the validity of the modified PPF controller, a simple experimental structure with an ATMD system driven by DC motor was built. The modified PPF control algorithm was implemented on Atmel 128 microcontroller. The experimental result shows that the modified PPF controller can also suppress vibrations for the real structure.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.1
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• pp.71-78
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• 2002

This paper is concerned with the design and implementation of magnetic damper system to reduce the vibration of suspension system actively. Cylindrical type electro-magnetic actuator with permanent magnet is analyzed and effective controller design is made. Magnetic force analyzed and transfer function for the total system is determined by experimental data using error minimization method. For experiments, simple suspension structure system is utilized, in which a magnetic damper composed of permanent magnet and digital controller is attached. In order to drive the system, bipolar power amplifier of voltage control type is utilized. Stable and high speed control board is used to perform digital control logic for the given system. This paper shows that the magnetic damper system using phase-lead controller excellently reduces vibration of 1-D.O.F (degree of freedom) suspension system.

• The Plant Pathology Journal
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• v.17 no.3
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• pp.115-122
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• 2001

Potato virus X (PVX) is a flexuous rod-shaped virus containing a single plus-strand RNA. Viral RNA synthesis is precisely regulated by regulatory viral sequences and by viral and/or host proteins. RNA sequence element as well as stable RNA stem-loop structure in the 5' end of the genome affect accumulation of genomic RNA and subgenomic RNA (sgRNA). The putative sgRNA promoter regions upstream of the PVX triple gene block (TB) and coat protein (CP) gene were critical for both TB and CP sgRNA accumulation. Mutations that disrupted complementarity between a region at the 5' end of the genomic RNA and the sequences located upstream of each sgRNA initiation site is important for PVX RNA accumulation. Compensatory mutations that restore complementarity restored sgRNA accumulation levels. However, the extent of reductions in RNA levels did not directly correlate with the degree of complementarity, suggesting that the sequences of these elements are also important. Gel-retardation assays showed that the 5' end of the positive-strand RNA formed an RNA-protein complex with cellular proteins, suggesting possible involvement of cellular proteins for PVX replication. Future studies on cellular protein binding to the PVX RNA and their role in virus replication will bring a fresh understanding of PVX RNA replication.