• Journal of Korean Society of Steel Construction
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• v.15 no.2
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• pp.147-157
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• 2003

The application in steel structures is increasing the mill sheet for the weathering steels by minimum maintenance cost in a life cycle cost. These have been collected and statistically analyzed to investigate chemical compositions, mechanical properties, weldability indices, weathering index and impact absorbed energy. From this study, although the band of dispersion in chernical compositions, mechanical properties and impact absorbed energy of the weathering steels appeared a little larger, the results revealed that these values have adequately satisfied the standard values of the Korean Standard. Furthermore, it was found that the weldability indices and the weathering index for the weathering steels have respectively satisfied the value prescribed by the Japanese Highway Specification and ASTM.

• Journal of the Korean Society of Safety
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• v.30 no.5
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• pp.52-58
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• 2015

Although lots of safety inspection and precision safety diagnosis have been conducted on concrete retaining wall, there is no comprehensive analysis on the basis of the accumulated data associated with the statistic. Especially, the concentrated management is necessary on the evaluation items that cause critical damages for the efficient performance. In this regard, this study conducted a correlation analysis between the 18 condition evaluation items and defect index for the concrete retaining wall as well as how each item affects the final defect index as much as in the manual. As a result, correlation coefficient between sliding and overturning was 0.601, which means that they have a strong correlation, and the most influential item on defect index is the condition of drainage that scored the 0.750 correlation coefficient. In addition, as a result of regression analysis, the condition of drainage with the 0.683 correlation coefficient has a strong correlation with the defect index. If the condition evaluation items are integrated or readjusted based on the results of the statistical analysis in this study, the more efficient and accurate maintenance will be possible.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.987-997
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• 2008

Successful design, construction and maintenance of geotechnical structure in soft ground and marine clay demands prediction, control, stability estimation and monitoring of settlement with high accuracy. It is important to predict and to estimate the compression index of soil for predicting of ground settlement. Lab. and field tests have been and are indispensable tools to achieve this goal. In this paper, Artificial Neural Networks (ANNs) model with Levenberg-Marquardt Algorithm and field database were used to predict compression index of soil in Korea. Based on soil property database obtained from more than 1800 consolidation tests from soils samples, the ANNs model were proposed in this study to estimate the compression index, using multiple soil properties. The compression index from the proposed ANN models including multiple soil parameters were then compared with those from the existing empirical equations.

• Journal of the korean academy of Pediatric Dentistry
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• v.11 no.1
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• pp.215-232
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• 1984

The purpose of this research was to analyze the relationship between parents' attitudes toward their children's dental health and dental plaque index. Dental plaque index was obtained through oral examination of 118 children(female 40, male 78) with primary dentition The maintenance status of children's dental health though parents' aids was evaluated by means of questionaire to which 79 persons among the 118 children's parents answered. The results were as follows : 1. In children with primary dentition, toothbrushing together with toothbrushing instruction and continuous reinforcement had decreased plaque accumulation progressively. 2. Dental plaque index before toothbrushing showed that dental plaque was accumulated more in the buccal surfaces of teeth in the maxilla and in the lingual surfaces of teeth in the mandible. It was higher in the posterior teeth than in the anterior teeth and in the maxillary teeth than in the mandibular teeth. 3. Dental plaque index of childern was inversely proportional to the level of education of their parents. 4. Those parents who have much knowledge of oral hygiene were more positive toward their children's oral hygiene.

• The Korean Journal of Health Service Management
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• v.8 no.2
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• pp.187-195
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• 2014

To improve oral hygiene management, the effects of toothbrush training on general oral hygiene based on the simplified oral hygiene index(S-OHI) and degree of knowledge about toothbrushing were examined. Pre-and post-training changes in the S-OHI (lower score = better oral health status) showed a significant decrease in score in all variables (gender, age, marital status, occupation, and level of education).Pre- and post-training changes in the degree of knowledge about toothbrushing showed a significant increase. Negative correlations between the S-OHI, oral health status, and degree of knowledge about toothbrushing and the S-OHI and the Decayed, Missing, Filled (DMF) index (the better the oral cavity environment, the lower the DMF index) were observed. Positive effects of repeated toothbrush training on the maintenance of healthy oral cavity environment and continuous oral health management were observed, as reflected by the correct toothbrushing-related knowledge and skills.

• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.64-70
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• 2019

Wireless sensors have been developed in numerous ways for enhancing the convenience of installation, management and maintenance of sensors. Energy harvesting wireless sensors, which can collect energy from the external environment for permanent usage without the need of recharging and exchanging batteries, have been developed and employed used in Internet of Things and at various industrial sites. Energy harvesting wireless sensors are significantly affected by the sensor lifespan to sudden variation in the external environment. Furthermore, reduction in the sensor operating timespan can greatly affect the characteristics of the devices connected through a network. In this paper, a system performance index is proposed that can comprehensively evaluate the lifespan of a solar cell wireless sensor, determine the characteristics of devices connected to the associated network, and recommend dynamic power distribution control for improving the system performance index. Improvement in the system performance index was verified by applying the proposed dynamic power distribution control to an air conditioner network system using a solar cell wireless sensor. Obtained results corroborate that the dynamic power distribution control can extend the lifespan of the incorporated wireless sensor and reduce the air conditioner's power consumption.

• Journal of Technologic Dentistry
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• v.43 no.1
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• pp.19-28
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• 2021

Purpose: This study aimed to obtain basic data on oral health improvement by investigating the EQ-5D index according to the oral prosthesis status of elderly persons aged 65 years or older in Korea using the Seventh Korea National Health and Nutrition Examination Survey. Methods: In this study, 3,426 elderly persons aged 65 years or older were included to analyze the relationship between the dental prostheses status and EQ-5D index in the collected data. Results: Compared to the "complete denture" in oral prosthesis, EQ in case of no dental prostheses or fixed dental prostheses is comparable to removable prosthetics such as "no dental prostheses," "one fixed bridge," and "two or more fixed bridges." Removable partial denture and complete denture required for the maxillary and mandibular EQ-5D index were significantly higher in "not necessary" than in "complete denture necessary" in all the elderly persons. Conclusion: The condition of the dental prosthesis and the need for a removable partial denture and complete denture for the elderly's EQ-5D index were confirmed, and it was found that the fixed dental prostheses were more effective than the removable dental prostheses. Therefore, oral health education programs for the elderly should be developed to promote dental function and oral health maintenance.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.101-109
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• 2008

Many researchers have reported that adding steel fiber to concrete improved its tensile and flexural strength significantly, but relatively few studies have been made on the compressive behavior of steel fiber-reinforced concrete. It is still less in case of high strength steel fiber-reinforced cementitious composites(SFRC). The main objective of this research is to examine the effect of adding steel fiber on the compressive strength of high strength SFRC using fiber reinforcing index(RI, $V_f(I_f/d_f)$). It was found from the study that compressive strength was noticeably increased in proportion to RI. In conclusion, the relationship between Reinforcing Index(RI) and compressive strength in case of high strength steel fiber-reinforced cementitious composites was suggested.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.2
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• pp.149-155
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• 2008

The road construction, as part of effort to ease the worsening traffic, has been underway throughout the nation, while the existing road has been increasingly losing its load carrying capacity due to such factors as heavy traffic and weathering. In the case of site, the soil type, plasticity index, and specific gravity were SC, 12.2%, and 2.66, respectively. The maximum dry density, optimum moisture content and modified CBR were $1.895g/cm^3$ (Modified Compaction D), 13.6%, and 16.2%, respectively. A correlation of coefficient expressed good interrelationship by 0.90 between the CBR estimated from a dynamic penetration index of dynamic cone penetrometer test and a deformation modulus converted from a dynamic deflection modulus obtained from a portable FWD test.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.63-72
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• 2009

This study aims at establishing the decision-making support system for the highway assets, long-term performance presumption and evaluation of asset value, which are appropriate for Korea, and proposing the methods of the optimal engineering method and the timing decision for the preventive maintenance through the project evaluation, the optimization method and life-cycle analysis related to the highways. In order to supplement the current problem of the near-sighted budget management system, which chooses the maintenance place of the highway, depending on the level of the budget with fixed amount, the long-term required budget prediction system and the economy principle were introduced, so that the pavement agency can predict the level of the required budget, and it was aimed to develop the pavement asset evaluation system to maintain the performance of the highway with the minimum of the cost. In the use of the highway pavement asset evaluation system, to maintain the appropriate level of the pavement evaluation index, when the budget was efficiently established in the reference of the required maintenance budget for the chosen section of the highway in the year concerned, it was possible to analyze the most rational pavement maintenance budget. With this result, it is estimated to prevent the unnecessary waste of budget in advance, and through the development of the decision-making system for the long-term performance presumption and the asset value estimation of the pavement, it is expected to able to analyze the previous evaluation of the project related to the highway and the feasibility of introduction.