• Proceedings of the KSME Conference
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• 2003.04a
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• pp.643-647
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• 2003

Power plant Piping operating at elevated temperature often fails prematurely by the growth of microcracks under creep conditions. Therefore, the life assessment of high temperature components that contain cracks is an important technological problem. The mechanisms of crack growth in simple metals and alloys have been investigated using both mechanical and microstructural approaches. In this study, life prediction accounting for creep, crack growth and thermal stress is analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.400-403
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• 2004

This paper presents an optimum design of journal bearings using a hybrid method to find the solutions of optimization problem. The present hybrid algorithm, namely Enhanced Artificial Life Algorithm(EALA), is a synthesis of an artificial life algorithm(ALA) and the random tabu search(R-tabu) method. EALA is applied to the optimum design of journal bearings supporting simple rotor. The applicability of EALA to optimum design of rotor-bearing system is exemplified through this study.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.1
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• pp.73-77
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• 1993

This paper considers an Economic Order Quantity Model under random life cycle. It is assumed that the life cycle of the product is unknown; a random variable. Three cost parameters are considered; ordering cost, inventory carrying cost and salvage cost. Expected total cost is the optimization criterion. We show that the optimal cycle length is unique and finite, and present a simple line search method to find an optimal cycle length.

• Journal of Convergence for Information Technology
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• v.8 no.1
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• pp.123-130
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• 2018

The subjects of this study were municipal citizens of Gyeongsangbuk-do Province and selected 250 members of the sports clubs as members. The sampling method for the data was used with simple ramdom sampling method, self-administration method. After questionnaire was distributed and retrieved, a total of 200 questionnaires were analyzed except for 50 items which were judged to be lack of credibility (double entry, no entry, insufficient data). For the data analysis, frequency analysis, ${\chi}^2$, factor analysis, reliability analysis, and one-way ANOVA were conducted in this study. First, there was no significant difference in life satisfaction among the participants. However, there was a significant difference in leisure satisfaction according to age. Second, there was a statistically significant difference in the life satisfaction of the athletes according to educational background, and there was a statistically significant difference in leisure satisfaction according to educational background.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1655-1658
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• 2003

Chemoselective N-benzenesulfonylation of aliphatic amines using 2-(4-nitrobenzenesulfonyl)-4,5-dichloropyridazin-3(2H)-one (2) gave the corresponding 4-nitrobenzenesulfonamides in good or excellent yield. This method is a simple, mild and general procedure for the chemoselective N-benzenesulfonylation of aliphatic amines.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.4
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• pp.372-376
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• 2010

Electrolytic capacitors have been widely used in power electronics system because of the features of large capacitance, small size, high-voltage, and low-cost. Electrolytic capacitors, which is most of the time affected by aging effect, plays a very important role for the power electronics system quality and reliability. Therefore it is important to estimate the parameter of an electrolytic capacitor to predict the failure. The estimation of the equivalent series resistance(ESR) is important parameter in life condition monitoring of electrolytic capacitor. This paper proposes a simple technique to measure the ESR of an electrolytic capacitor. This method uses a switching DC/DC boost converter to measure the DC Bus capacitor ESR of power converter. Main advantage of the proposed method is very simple in technique, consumes very little time and requires only simple instruments. Simulation results are shown to verify the performance of the proposed method.

• Parasites, Hosts and Diseases
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• v.56 no.2
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• pp.175-181
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• 2018

The giant roundworm Ascaris infects pigs and people worldwide and causes serious diseases. The taxonomic relationship between Ascaris suum and Ascaris lumbricoides is still unclear. The purpose of the present study was to investigate the genetic diversity and population genetic structure of 258 Ascaris specimens from humans and pigs from 6 sympatric regions in Ascaris-endemic regions of China using existing simple sequence repeat data. The microsatellite markers showed a high level of allelic richness and genetic diversity in the samples. Each of the populations demonstrated excess homozygosity (Ho0). According to a genetic differentiation index (Fst=0.0593), there was a high-level of gene flow in the Ascaris populations. A hierarchical analysis on molecular variance revealed remarkably high levels of variation within the populations. Moreover, a population structure analysis indicated that Ascaris populations fell into 3 main genetic clusters, interpreted as A. suum, A. lumbricoides, and a hybrid of the species. We speculated that humans can be infected with A. lumbricoides, A. suum, and the hybrid, but pigs were mainly infected with A. suum. This study provided new information on the genetic diversity and population structure of Ascaris from human and pigs in China, which can be used for designing Ascaris control strategies. It can also be beneficial to understand the introgression of host affiliation.

• Journal of Life Science
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• v.10 no.4
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• pp.374-379
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• 2000

This study was attempted to evaluate an agonistic activity to benzodiazepine receptor of several medicinal pants, which have been used as sedatives in oriental medicine. The activities of the methanol extracts of composite preparation of oriental drugs were compared with those of the simple drugs, furthermore, the active fraction was found out from the simple preparation. Inhibitory effects of composite preparations, Cyperus rotundus/Acorus gramineus, Thuja orientalis/Euphoria longan, Thuja orientalis/Albizzia julibrissin, on the binding of ${[^3H]}$Ro15-1788, a selective benszodiazepine receptor antagonist to benzodiazepine receptor of rat cortices, were observed to be lower than those of corresponding simple preparations. These unexpected results suggest that some components of the composite druge may rather act as an obstacle, not to show the sinergistic effect. The methanol extracts of Cyperus rotundus having the highest activity were fractionated using polar and nonpolar solvents to give ethylacetate and hexane fractions, respectively. The ethylacetate fraction containing relatively polar components exhibited much higher activity than the hexane fraction, which consiste of nonpolar agonist, binding to benzodiazepine receptor. However, in the presence of GABA, this fraction inhibited ${[^3H]}$flunitrazepan binding, and these positive GABA shift supported the strong possibility of agonistic activity to benzodiazepine receptro. As a result, it may be concluded that the substance or substances with neurochemical properties as a benzodiazepine receptor agonist may contribute to the sedative property of Cyperus rotundus.

• Computers and Concrete
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• v.6 no.1
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• pp.1-18
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• 2009

Chloride diffusivity of concrete is a crucial material parameter for service life determination and durability designing of marine concrete. Many research works on this issue have been conducted, varying from empirical solutions obtained experimentally to image analysis, based on multi-scale modeling. One of the simple approaches is to express the chloride diffusivity of concrete by a multi-factor function, however, the influences of various factors on the chloride diffusivity are ambiguous. Furthermore, the majority of these research works have not dealt with the carbonation process of concrete, although this process affects the chloride diffusivity of concrete significantly. The purpose of this study is to establish a simple approach to calculate the chloride diffusivity of (non)carbonated concrete. The chloride diffusivity of concrete should be defined, based on engineering and scientific knowledge of cement and concrete materials. In this paper, a lot of parameters affecting the chloride diffusivity, such as the diffusivity in pore solution, tortuosity, micro-structural properties of hardened cement paste, volumetric portion of aggregate, are taken into consideration in the calculation of the chloride diffusivity of noncarbonated concrete. For carbonated concrete, reduced porosity due to carbonation is calculated and used for calculating the chloride diffusivity. The results are compared with experimental data and previous research works.

• Journal of Korean Society for Quality Management
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• v.29 no.3
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• pp.49-65
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• 2001

This paper presents new compromise ALT plan which is applied to situations that true relationship between stress and parameters is not known exactly. The assumed failure distribution of this study is one of location-scale family, i. e., exponential, Weibull, and lognormal distributions which have been ones of the popular choices of failure distributions. The method of applying the stress is constant, and the censoring mechanism is Type I censoring. Compared with existing compromise plans under true simple linear model in terms of statistical efficiency, the efficiency of new compromise plan is better than the corresponding other compromise ones in most cases. For case when true model is quadratic, this plan can be used without any severe loss in statistical efficiency. The proposed new compromise ALT plan is illustrated with a numerical example and sensitivity analyses are conducted to study effects of pre-estimates of design parameters.