• Journal of the Korea Convergence Society
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• v.10 no.9
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• pp.55-61
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• 2019

The purpose of this study was to investigate the correlation between the hand dexterity and grip strength of 8-10 year elementary school children and 20-24 year college students. This study was conducted on 77 elementary school children aged 8-10 years old and 50 college students aged 20-24 years. The chopsticks manipulation test (CMT) and dymanomenter were used to evaluated hand dexterity and grip strength. In this study, the correlation between hand dexterity and grip strength, and the age, hand dexterity and grip strength of the subjects were compared. hand dexterity between 8-10 year old and 20-24 year old students were statistically different between 8 and 9 year olds, and the control was between 8 and 20-24 year old students. There were statistically significant differences. In addition, in the correlation between age, hand dexterity and grip strength, age and grip strength were positively correlated, and age and hand dexterity were negatively correlated. These results may contribute to the development of children's hand function and the fusion approach.

• KCI Concrete Journal
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• v.13 no.2
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• pp.10-18
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• 2001

The spectral analysis of surface waves (SASW) method, which is an in-situ seismic technique, has mainly been developed and used for many years to determine the stiffness profile of layered media (such as asphalt concrete and layered soils) in an infinite half-space. This paper presents a modified experimental technique for nondestructive evaluation of in-place cement mortar compressive strength in single-layer concrete slabs of rather a finite thickness through a correlation to surface wave velocity. This correlation can be used in the quality control of early age cement mortar structures and in evaluating the integrity of structural members where the infinite half space condition is not met. In the proposed SASW field test, the surface of the structural members is subjected to an impact, using a 12 mm steel ball, to generate surface wave energy at various frequencies. Two accelerometer receivers detect the energy transmitted through the medium. By digitizing the analog receiver outputs, and recording the signals for spectral analysis, surface wave velocities can be identified. Modifications to the SASW method includes the reduction of boundary reflections as adopted on the surface waves before the point where the reflected compression waves reach the receivers. In this study, the correlation between the surface wave velocity and the compressive strength of cement mortar is developed using one 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slab of 2,000 psi (140 kgf/$\textrm{cm}^2$) and two 36"x36"x4"(91.44$\times$91.44$\times$91.44 cm) cement mortar slabs of 3,000 psi (210 kgf/$\textrm{cm}^2$).

• Restorative Dentistry and Endodontics
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• v.28 no.6
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• pp.491-497
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• 2003

The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using confocal laser scanning microscope and microtensile bond strength test of two adhesive systems. The dentin surface of human molars. sectioned to remove the enamel from the occlusal surface. Either Scotchbond Multi-Purpose(3M Dental Product, St. Paul, MN, U.S.A) or Clearfil SE Bond (Kuraray, Osaka, Japan) was bonded to the surface. and covered with resin-composite. The resin-bonded teeth were serially sliced perpendicular to the adhesive interface to measure the hybrid layer thickness by confocal laser scanning microscope. The specimen were trimmed to give a bonded cross-sectional surface area of $1\textrm{mm}^2$, then the micro-tensile bone test was performed at a cross head speed of 1.0 mm/min. All fractured surfaces were also observed by stereomicroscope. There was no significant differences in bond strengths the materials(p>0.05). However. the hybrid layers of three-step dentin adhesive system, SM, had significantly thicker than self-etching adhesive system. CS(p<0.05). Pearson's correlation coefficient showed no correlation between hybrid layer thickness and bond strengths(p>0.05). Bond strengths of dentin adhesive systems were not dependent on the thickness of hybrid layer.

• Journal of Powder Materials
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• v.30 no.3
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• pp.217-222
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• 2023

Machine learning-based data analysis approaches have been employed to overcome the limitations in accurately analyzing data and to predict the results of the design of Nb-based superalloys. In this study, a database containing the composition of the alloying elements and their room-temperature tensile strengths was prepared based on a previous study. After computing the correlation between the tensile strength at room temperature and the composition, a material science analysis was conducted on the elements with high correlation coefficients. These alloying elements were found to have a significant effect on the variation in the tensile strength of Nb-based alloys at room temperature. Through this process, a model was derived to predict the properties using four machine learning algorithms. The Bayesian ridge regression algorithm proved to be the optimal model when Y, Sc, W, Cr, Mo, Sn, and Ti were used as input features. This study demonstrates the successful application of machine learning techniques to effectively analyze data and predict outcomes, thereby providing valuable insights into the design of Nb-based superalloys.

• The Journal of the Convergence on Culture Technology
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• v.10 no.4
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• pp.193-199
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• 2024

The purpose of this study was to confirm the relationship between self-esteem, family strength, and awareness of support for the elderly among college students, and to identify factors that affect awareness of support for the elderly. The participants of the study were 131 college students, and data was collected using a structured questionnaire from March 26 to April 11, 2024. Data analysis was performed using Independent t-test, One way ANOVA, Pearson's correlation coefficients, and multiple regression analysis. The results of the study showed a positive correlation between self-esteem and family strength (r=.49, p<.001), and between family health and awareness of support for the elderly (r=.30, p<.001). Factors that influence the participant's awareness of support for the elderly are age (β=-.18, p=.029), sibling status (β=.18, p=.027), and family strength (β=.26, p=.002). Based on the results of this study, it is necessary to have college students actively participate in programs related to the elderly so that they can have a positive attitude toward the elderly and establish correct values through continuous interaction with the elderly.

• PNF and Movement
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• v.21 no.2
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• pp.223-229
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• 2023

Purpose: Assessing physical strength and muscle mass is crucial, but many methods rely on specialized equipment, which can be challenging. In situations where a quick and straightforward test is needed, the sit-to-stand test (STST) proves useful. Although several studies have investigated STST and muscle mass separately, the actual correlation between these two factors has not been extensively researched. Hence, the objective was to comprehensively investigate the correlations between the different tests. Methods: The study participants consisted of 20 healthy young men in their 20s. In this study, measurements were taken for muscle mass, the five-times sit-to-stand test, the 30-second sit-to-stand test, and the 1-minute sit-to-stand test. The results of each test were analyzed using Pearson's correlation analysis. Results: Although no significant correlation was found between muscle mass and STST, interestingly, significant correlations were observed among the different types of STST. Conclusion: The STST is a rapid and straightforward test used to assess lower limb strength and balance ability in individuals. However, there is a dearth of research on STST conducted in domestic settings. Based on the findings of this study, further research is necessary to establish age- and gender-specific reference values for STST. This will allow its broader application, encompassing not only older adults and patients but also healthy individuals.

• Bulletin of the Korean Chemical Society
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• v.8 no.5
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• pp.427-428
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• 1987

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.239-242
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• 2002

This study is intended to investigate the relationship between rebound value of P type schmidt hammer and the compressive strength with various aggregates, and a series of experiments about early strength quality control by P type schmidt hammer was performed. According to the results, the compressive strength of concrete using basalt and limestone aggregate is higher by 3% and lower by 4% than that of concrete using granite aggregate respectively. Concrete using basalt and lime stone aggregate show high rebound value in vertical strike. Estimation of the compressive strength does not show differences in horizontal strike, but the compressive strength is estimated high in order of granite, basalt and limestone aggregate in vertical strike. A good correlation between the rebound value of schmidt hammer and the compressive strength is confirmed regardless of aggregate types, so it could be possible to control the quality of concrete by P type schmidt hammer test when basalt and limestone aggregates are used at the same time.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.195-200
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• 1995

This paper presents the practical use of high strength concrete on 28-story Samsung Shin-dacbang Housing-Commercial Combined Building with 8-story basements located in Seoul. 700 Kg/$\textrm{cm}^2$ compressive Strength concrete was placed for basement core-walls and 500 kg/$\textrm{cm}^2$ concrete was used for structural frames up to 10th floor. The thermal sensors were installed prior to concrete casting into the core walls to measure the heat of hydration during hardening process. The correlation of core strength to the standard cylinder test strength was also discussed. The successful utilization of 500 and 700 kg/$\textrm{cm}^2$ concrete shows that the practical application of high strength concrete has a great potential to the high-rise R.C building construction.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.220-223
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• 2004

It is fact that the cement is the most important material to harden the mortar and concrete, and Potland cement is used widely. Also, the chemical and physical properties of cement are different according to the kinds of cement. This is an experimental study to compare and analyze the influence of cement strength on the compressive strength of mortar to improve the quality of mortar and concrete. According to test results, it was found that correlation between cement strength and mortar strength was very high in all mixture.