• Proceedings of the Korean Institute of Building Construction Conference
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• 2011.05a
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• pp.45-47
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• 2011

Finishing materials used during the construction of reinforced concrete structures aid in providing resistance to carbonation and help ensure the durability of a structure. However, detailed examinations of this phenomena using data gained from long-term outdoor exposure are not only lacking, but also are not taken into account as factors affected by the local environment. In this research, the velocity coefficient in terms of carbonation is compared as a difference according to the local region and the averaged annual temperature, and the carbonation-preventive effects of finishing materials are analyzed. As an outcome of this study, the results of long-term carbonation can be evaluated from carbonation resistance R induced by an acceleration carbonation test.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.2125-2129
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• 2008

In present, RCM has been hot issue in the domestic railway industry areas. Based on this circumstance, in this paper, for the purpose of an effective RCM system construction, a suitable organization structures which are to be applied to the railway system is proposed. Some examples and descriptions about the responsibilities and the roles which should be done by each RCM team, during the RCM analysis, as step by step for RCM analysis are also described. By using the formalized organization, the tasks for maintenance are allocated to each staff and the data for RCM analysis could be managed, systematically, as well. To sum up, it would be expected that based on the systematic organization structure for RCM analysis, the results of RCM analysis, that mean the maintenance methods and intervals for preventive maintenance, on specific railway system could be more reliable and accurate.

• Journal of the Korea Society for Simulation
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• v.28 no.4
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• pp.1-10
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• 2019

The Sea Water Reverse Osmosis (SWRO) plant should take into account the availability of the plant from the design stage for long-term and continuous fresh water production. As it occurs, it is necessary to establish a corrective maintenance plan and preventive maintenance plan to maintain availability. In the field of complex engineering structures such as seawater desalination plants, it is difficult to estimate the reliability or availability of the system in a mathematical way. This study develops RAM analysis framework and model, and proposes discrete event simulation model as a application sowtware specialized for seawater desalination plant. Considering the characteristics of the plant maintenance, in case of corrective maintenance, we propose a preventive maintenance policy that not only repairs or replaces a single-broken part, but also simultaneously maintains all accessible parts according to the level of overhaul. A case study was conducted to estimate the availability of the system based on the field data of the seawater desalination plant in Korea and Saudi Arabia. The result was close to the expected availability of the plant.

• Journal of Korean society of Dental Hygiene
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• v.17 no.1
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• pp.13-25
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• 2017

Objectives: The purpose of this study was to compare colony forming unit (CFU) method and multiplex real-time polymerase chain reaction (MRT-PCR) method for accurate quantitative analysis of bacteria. Methods: We compared the CFU method and the MRT-PCR method, which are still used in Korea, for Prevotella intermedius (P. intermedius), a periodontal disease pathogen selected by MRT-PCR, and Streptococcus mutans (S. mutans), a dental caries causative organism. The subjects of this study were 30 patients who visited the C dental hospital. Results: Total microorganisms in MRT-PCR method were significantly higher in both types of bacteria (p<0.05), since DNA of dead bacteria was also analyzed. This was because the periodontal dise(-) anaerobes, and even dead bacteria contain large amounts of toxic substances called LPS in the extracellular membrane, and fimbriae and pili, which are motility structures, still remain as a strong toxic substance in periodontal tissue. Conclusions: Therefore, in terms of the total amount of bacteria found, the MRT-PCR method will be a useful technique for searching all the bacteria in the oral cavity including live bacteria, as well as sterilization.

• Bulletin of the Society of Naval Architects of Korea
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• v.18 no.1
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• pp.1-8
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• 1981

To contribute to the preventive measures against local vibrations of ship's deck panels, some investigations into the prediction method of the natural frequency of the vibration of stiffened plates were done. Firstly, an analytical method based on the orthotropic plate analogy and the Rayleigh method using eigenfunctions of the Euler beam was shown, and numerical results of a regularly stiffened plate were compared with experimental results. And then, the method was extended to stiffened plates having one or two irregular stiffeners to obtain an approximate formula showing the relation between the change of the natural frequency and the size of the irregular stiffeners. The latter case was investigated for the purpose of providing a convenient design manual applicable to cure of local resonant vibrations of ships' deck panels by additional reinforcement of one or two stiffeners. In the analytical development the boundary was assumed to be rigidly supported and elastically restrained against rotation. In the experiment, however, only an extreme case i.e. simply supported boundary was investigated. The results of the investigation show that there is a fairly good conformity between the analytical results and the experimental ones in the first case, and that the approximate formula for the second case is confirmed also to be reliable for the design purpose. Considering that actual boundary conditions of deck panels in ship structures lie mostly somewhere between the simple support and the fixed, the authors discussed problems of the joint efficiency at the boundary of deck panels from the viewpoint of the practical application of the formulae.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.22-32
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• 1990

Associations between type A behavior Pattern (TABP) and parental social control were examined by a questionnaire survey in a sample of 803 undergraduates of the three universities in Daegu city in 1988. TABP was assessed by the Student Jenkins Activity Survey (SJAS, short form) and social control of parents by Bernstein and Brandis' Index of control and communication which were both dichotomized by median. The mean age of the sample was 20.7 (standard deviation, 2.2) and mean of total score of SJAS was 5.6 with its standard deviation and median, 2.7 and 5, respectively. In stratified analysis for TABP-social control association by the native place, sex and socioeconomic status (SES), males of rural origin with low SES showed odds ratio (OR), 2.49 but those with high SES 0.40. For females of rural origin, those with low SES showed OR, 1.02, whereas those with high SES did 0.35. For those who was of urban origin, males with low SES had OR 1.27, and those with high SES did 1.29. Females with high SES showed 0.85 and those with low SES 0.67. None of the TABP-social control associations among the strata showed confidence intervals not including unity. In multiple logistic regression by native place, for those with rural origin the only term showed a statistically significance was the social control-SES of parents interaction, OR 3.99 (95% confidence interval, $1.03{\sim}15.46$). For those of urban origin, none of the terms are statistically significant. These results suggest a social upward mobility by education of the rural disadvantaged group and a Confucian idea that regards academic achievement as one of social virtues, both of which may reflect the different sociocultural structures from the West.

• Journal of Preventive Medicine and Public Health
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• v.32 no.4
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• pp.467-472
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• 1999

Objectives: This study was conducted to evaluate the cytotoxicity of gallium arsenide(GaAs), indium phosphide(InP) and indium arsenide(InAs) all of which are used a$ the semiconductor eletments in semiconductor industry. Methods: Cytotoxicity id the alveolar macrophage was evaluated by the measurement of in vitro magnetometry, LDH release assay and histological examination. Results: The relaxation curves by the in vitro magnetometry showed that GaAs has the cytotoxicity for the alveolar macrophage which is more significant in the higher dosages, while this cytotoxicity is not appeared in the groups added with InP or InAs or PBS. In the decay constant for two minutes after magnetization, GaAs-added groups showed a significant decrease with increasing doses, but both InP- and InAs-added groups did not show any significance. The LDH release assay showed a dose-dependent increasing tendency in the GaAs-, InP- and InAs-added groups. In terms of cellular morphological changes, GaAs-added groups revealed such severe cellular damages as prominent destructions in cell membranes and their morphological changes of nucleus, while InP- and InAs-added groups remained intact in intracellular structures, except for cytoplasmic degenerations. Conclusions: It is suggested that GaAs is more influential to cytotoxicity of alveolar macrophages than InP and InAs.

• Health Policy and Management
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• v.30 no.2
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• pp.253-262
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• 2020

Background: The public health care system of a country is shaped and driven by its historical background as well as social, economic, and cultural structures. This study sheds light on the unique features, strengths, and weaknesses of the health insurance systems of South Korea (Korea) and Peru. Methods: The capacity mapping tool was used to explore the Korean and Peruvian population and geographical structures; health insurance laws, regulations, and policies; payment systems; eligibility and contribution collection; and long-term care insurance. Results: The study found that the Korean government took the lead in integrating multiple insurers into a single-payer system in an effort to reinforce and stabilize its health insurance system in 2000. Peru has been developed mixed model such based on taxes and contributions, to address a gap between different social classes. Peruvian government developed a two-axis system, one for low-income earners, financed by taxes, and another financed by contributions paid by workers and government officials in the formal sector. Peru has introduced many variations to its fee payment and insurer systems, target population, and coverage scope, and maintains its health insurance system accordingly to this day. Conclusion: The current study provides observation of the Health Insurance System in two different countries and helps to understand possible ways to improve the health insurance system in both countries. Based on this study, Peru will be able to see how its system differs from Korea's and benefit from the related policy implications.

• Proceedings of the Korean Society for Rock Mechanics Conference
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• 2007.03a
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• pp.64-80
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• 2007

This paper presents a case study on the excavation of a long tunnel(16.2km) named as "Sol-An tunnel", which connects between Mt. Dongbaek station and Dokye station in the Young-dong Railroad. This site is located in a complex geological region with faults, cavities and coal measures as sedimentary rocks area. It occurred geotechnical problems unexpectedly by running water when tunnelling in limestone area within those geological structures. This tunnel caused surface settlements through the decrease of ground water level and soil washed-out affecting by cavities and faults within limestone formation. This paper presents a analysis of source through a close investigation and measures. And also, does preventive measures about returns of settlements reflected by properties of limestones.

• Preventive Nutrition and Food Science
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• v.14 no.4
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• pp.354-357
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• 2009

Three compounds, vanillic acid, p-hydroxylcinnamic acid, p-hydroxybenzaldehyde have been isolated from the ethylacetate extract of Sparganium stoloniferum Buch.-Ham roots using silica gel open column chromatography, preparative thin-layer chromatography (pTLC) and reverse phase high performance liquid chromatography. The structures of the compounds were established on the basis of IR, extensive 1D NMR, and MS analyses. The ethylacetate (EtOAc) extract, vanillic acid, and p-hydroxybenzaldehyde showed $\alpha$-glucosidase inhibition activity of 72.71%, 20.13%, and 30.42%, at the concentration of 10 ${\mu}g/mL$, respectively. The EtOAc extract exhibited strong antioxidant activity with an $IC_50$ value of 24.37 ${\mu}g/mL$ against DPPH radical scavenging activity, the vanillic acid, p-hydroxylcinnamic acid, and p-hydroxybenzaldehyde with an $IC_50$ value of 2.10 ${\mu}M$, 1.59 ${\mu}M$, and 2.72 ${\mu}M$ against DPPH, respectively.