• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.668-671
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• 2004

Recently, the concern for mechanical properties at early age concrete are increasing because of the importance of the thermal stress and the determination of removal time of form work and prestressing work. In this study, an estimation for the development of compressive strength and elastic modulus with age in concretes isothermally cured $(10^{\circ}C,\;20^{\circ}C)$ and having W/C ratio of 30, 40, and $50\%$ were investigated. According to experiment results, the development of compressive strength and elastic modulus shows higher values at early ages as the W/C ratio decreases and curing temperature increases. When the maturity concept, for estimation of the strength, is adopted, a modification for W/C ratio is required at early ages.

• Journal of Korean Neurosurgical Society
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• v.59 no.3
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• pp.227-232
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• 2016

Various operative techniques are available for the treatment of craniosynostosis. The patient's age at presentation is one of the most important factors in the determination of the surgical modality. Minimally invasive suturectomy and postoperative helmet therapy may be performed for relatively young infants, whose age is younger than 6 months. It relies upon the potential for rapid brain growth in this age group. Its minimal invasiveness is also advantageous. In this article, we review the advantages and limitations of minimally invasive suturectomy followed by helmet therapy for the treatment of craniosynostosis.

• 보존과학연구
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• s.27
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• pp.181-201
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• 2006

In this study, radiocarbon dating by the benzene synthesis method and liquid scintillation counting method were performed for the age determination of coal sample at the Cheongok-dong archaeologicalsite, Ulsan. The results of radiocarbon age(BP year) are section Ga #1 $2920\pm50$ BP year, section Ga #5 $3100\pm55$BP year, section Ga #6 $2820\pm60$ BP year, section Na #5 $2650\pm50$ BP year. These ages were converted to calibrated age(AD/BC year) using high precision curve. The products on the excavation of Cheongok-dong archaeological site, Ulsan, section Ga #1 BC 1260-980 BC, section Ga #5 BC1460-1200 BC, section Ga #6 BC 1110~830 BC, section Na #5 BC 920-760 BC. Comparison of samples with radiocarbon and archaeological ages for revealed the approximation.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.251-258
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• 2003

The early -age behavior of base restrained reinforced concrete (RC) walls is analyzed using a three-dimensional finite element method in this study. After calculating the temperature and internal relative humidity variations of an RC wall, determination of stresses due to thermal gradients, differential drying shrinkage, and average drying shrinkage is followed, and the relative contribution of these three stress components to the total stress is compared. The mechanical properties of early-age concrete, determined from many experimental studies, are taken into consideration, and a discrete reinforcing steel derived using the equivalent nodal force concept is also used to simulate the cracking behavior of RC walls. In advance, to Predict the crack spacing and maximum crack width in a base restrained RC wall, an analytical model which can simulate the post-cracking behavior of an RC tension member is introduced on the basis of the energy equilibrium before and after cracking of concrete.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.sup3
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• pp.5-10
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• 2016

Breast cancer, the second cause of cancer-related death after lung cancer and the most common cancer in women after skin cancer, is curable if detected in early stages of clinical presentation. Knowledge as to any age cut-off points which might have significance for prognostic groups is important in screening and treatment planning. Therefore, determining a change-point could improve resource allocation. This study aimed to determine if a change point for survival might exist in the age of breast cancer diagnosis. This study included 568 cases of breast cancer that were registered in Breast Cancer Research Center, Tehran, Iran, during the period 1986-2006 and were followed up to 2012. In the presence of curable cases of breast cancer, a change point in the age of breast cancer diagnosis was estimated using a mixture survival cure model. The data were analyzed using SPSS (versions 20) and R (version 2.15.0) software. The results revealed that a change point in the age of breast cancer diagnosis was at 50 years age. Based on our estimation, 35% of the patients diagnosed with breast cancer at age less than or equal to 50 years of age were cured while the figure was 57% for those diagnosed after 50 years of age. Those in the older age group had better survival compared to their younger counterparts during 12 years of follow up. Our results suggest that it is better to estimate change points in age for cancers which are curable in early stages using survival cure models, and that the cure rate would increase with timely screening for breast cancer.

• Imaging Science in Dentistry
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• v.46 no.1
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• pp.1-7
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• 2016

Purpose: This study assessed the accuracy of age estimates produced by a regression equation derived from lower third molar development in a Thai population. Materials and Methods: The first part of this study relied on measurements taken from panoramic radiographs of 614 Thai patients aged from 9 to 20. The stage of lower left and right third molar development was observed in each radiograph and a modified Gat score was assigned. Linear regression on this data produced the following equation: Y=9.309+1.673 mG+0.303S (Y=age; mG=modified Gat score; S=sex). In the second part of this study, the predictive accuracy of this equation was evaluated using data from a second set of panoramic radiographs (539 Thai subjects, 9 to 24 years old). Each subject's age was estimated using the above equation and compared against age calculated from a provided date of birth. Estimated and known age data were analyzed using the Pearson correlation coefficient and descriptive statistics. Results: Ages estimated from lower left and lower right third molar development stage were significantly correlated with the known ages (r=0.818, 0.808, respectively, $P{\leq}0.01$). 50% of age estimates in the second part of the study fell within a range of error of ${\pm}1year$, while 75% fell within a range of error of ${\pm}2years$. The study found that the equation tends to estimate age accurately when individuals are 9 to 20 years of age. Conclusion: The equation can be used for age estimation for Thai populations when the individuals are 9 to 20 years of age.

• The Journal of the Petrological Society of Korea
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• v.11 no.3_4
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• pp.157-168
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• 2002

In Gimcheon area of the central Yeongnam massif granite gneiss occurrs with intercalated biotite gneiss at xenolith or restite. In order to understand the evolution of the central Yeongnam massif, it is essential to have absolute age information, but not many age data are available yet. Furthermore the previous age determinations from the study area are not compatible with the outcrop relationship. In this study we determined chemical ages from the zircon grains. We obtained ages of $1970\pm$ 78(l$\sigma$)Ma from the granite gneiss, $1814\pm$77(l$\sigma$)Ma from the outer rim of a rounded zircon and 1973$\pm$97(l$\sigma$)Ma from a longish zircon, both from the biotite gneiss. These ages seem to indicate the timing of granitic magma intrusion and subsequent metamorphism. Ages of $2954\pm$ 158($l\sigma$)Ma, 2440$\pm$58(l$\sigma$)Ma, and 2219$\pm$36($l\sigma$)Ma obtained from zoned core of the rounded zircon grain from the biotite gneiss suggest various geological events before such metamorphism of the biotite gneiss. Ages in the range of 1450~1670 Ma observed in zircons of both gniesses suggest later metamorphism that the granite gneiss and the biotite gneiss experienced together. The chemical age determination by electron probe micro-analyzer of this study utilized 1$\mu\textrm{m}$ beam diameter and it seems to be a very useful age determination from the zircons with complex growth history because of superior spatial resolution.

• Imaging Science in Dentistry
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• v.50 no.3
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• pp.237-243
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• 2020

Purpose: The aim of this study was to evaluate the clinical efficacy of a Tanner-Whitehouse 3 (TW3)-based fully automated bone age assessment system on hand-wrist radiographs of Korean children and adolescents. Materials and Methods: Hand-wrist radiographs of 80 subjects (40 boys and 40 girls, 7-15 years of age) were collected. The clinical efficacy was evaluated by comparing the bone ages that were determined using the system with those from the reference standard produced by 2 oral and maxillofacial radiologists. Comparisons were conducted using the paired t-test and simple regression analysis. Results: The bone ages estimated with this bone age assessment system were not significantly different from those obtained with the reference standard (P>0.05) and satisfied the equivalence criterion of 0.6 years within the 95% confidence interval (-0.07 to 0.22), demonstrating excellent performance of the system. Similarly, in the comparisons of gender subgroups, no significant difference in bone age between the values produced by the system and the reference standard was observed (P>0.05 for both boys and girls). The determination coefficients obtained via regression analysis were 0.962, 0.945, and 0.952 for boys, girls, and overall, respectively (P=0.000); hence, the radiologist-determined bone ages and the system-determined bone ages were strongly correlated. Conclusion: This TW3-based system can be effectively used for bone age assessment based on hand-wrist radiographs of Korean children and adolescents.

• The Korean Journal of Health Service Management
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• v.9 no.3
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• pp.115-126
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• 2015

Objectives : This research was performed to investigate the characteristics and determination factors of health care policy satisfaction and welfare recognition for health insurance & health care financing. Methods : The utilized data were 4,174 cases who responded to a welfare recognition survey in the 8th wave of the Korea Welfare Panel Study (2013). The statistical methodology used in this study is the multiple regression model. Results : The significant affecting factors of health care policy satisfaction were age, education, household income, welfare attitudes, and health status. Medical utilization & private medical insurance were not related to health care policy satisfaction. The affecting factors of health insurance reinforcement were age, health status, welfare attitudes. The affecting factors of health care financing expansion were age, economic activity type, medical utilization, welfare attitudes. The affecting factors of welfare attitudes were age, economic activity type, household income, health insurance, and health status. Conclusions : Health care policy satisfaction, health insurance reinforcement, and health care financing expansion were all affected by age and welfare attitude; but this was not the case for private health insurance. This study recommended that the Korean government provide active planning for reinforcement of health insurance and publicity of the health care system in order to accord with the prospects of people.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.2
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• pp.112-119
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• 2008

The fundamental data on the catch fluctuation in the rectangular set net according to the tide age were developed based on the catches recorded from the year 1986 to 2004 in the coastal waters of Hamdeok, Jeju. Total catch by the rectangular set net had a deep connection with the tide age. In particular, during increasing tide, total catch were reduced gradually from the neap tide to the high tide. As it turned out, the slope of total catch declined by degree and showed a correlation coefficient of determination of 0.76. On the contrary, in the case of decreasing tide, there was little sign of rise in total catch. In particular, large catch seemed to occur at the next tide to the neap tide. In the relation between the catch and the tide age, the level of the correlation coefficient chosen at $p{\leq}0.05$ decreased in the order rabbitfish(-0.84) and horse mackerel(-0.71), while the significance of other dominant species were not selected.