• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2015년도 춘계 학술논문 발표대회
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• pp.98-99
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• 2015

In the study, based on analysing bond strength of MPC and existing rapid harding grout according to shape of cross section, early ages shape of cross section is investigated about effect on bond strength to use MPC as an emergency repair material for road defects such as the form of a pot-hole. The result, MPC is about 10% higher than the shear bond strength rapid harding grout, about 20% higher bending bond strength.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2014년도 추계 학술논문 발표대회
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• pp.135-136
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• 2014

In this study, the experimental study on the early age compressive strength of cement mortar using anti freezer and hardening accelerator at low temperature was conducted. For this study, all of materials for experiment were kept in a low temperature for 24 hours before mortar mixing. After mortar curing at low temperature, compressive strength was measured at the early ages. Furthermore, properties of hardened cement material was analysed using TG-DTA and MIP.

• Journal of Chest Surgery
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• 제48권1호
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• pp.78-81
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• 2015

This study reports our early experience with thoracoscopic division of vascular rings. Three patients were reviewed; their ages at surgery were 25 months, 4 years, and 57 years. All patients were suffering from complete vascular rings involving combinations of the right aortic arch, left ligamentum arteriosum, Kommerell's diverticulum, and retroesophageal left subclavian artery. The median surgical time was 180.5 minutes, and the patients showed immediate recovery. Three complications, namely chylothorax, transient supraventricular tachycardia, and left vocal cord palsy, were observed. Our early experience indicates that thoracoscopic division of a vascular ring may provide early recovery and could be a promising operative choice.

• Journal of the Korea Concrete Institute
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• 제13권5호
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• pp.447-456
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• 2001

Many investigators have tried to represent the nonlinear behavior of stress-strain relationship of concrete using mathematical curves. Most of empirical expressions for stress-strain relationship, however, have focused on old age concrete, and were not able to represent well the behavior of concrete at an early age. Where wide understanding on the behavior of concrete from early age to old age is very important in evaluating the durability and service life of concrete structures. In this paper, effect of 5 different strength levels and ages of from 12 hours to 28 days on compressive stress-strain relationship was observed experimentally and analytically. Tests were carried out on $\phi$100${\times}$200mm cylindrical specimens water-cured at 20${\pm}$3$^{\circ}C$. An analytical expression of stress-stain relationship with strength and age was developed using regression analyses on experimental results. For the verification of the proposed model, the model was compared with present and existing experimental data and some existing models. The analysis shows that the proposed model predicts well experimental data and describes well effect of strength and age on stress-strain relationship.

• Journal of the Korea Institute of Building Construction
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• 제12권4호
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• pp.369-376
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• 2012

In this study, to reduce the hydration heat velocity (HHV) of high-strength mass concrete at early ages, phase change materials (PCM) that could absorb hydration heat were applied, and the changes in autogenous shrinkage were investigated, as well as the relationship between the hydration temperature and autogenous shrinkage. The acceleration of the cement hydration process by the PCM leads to an early setting and a higher development of the compressive strength and elastic modulus of concrete at very early ages. The function of PCM could be worked below the original melting point due to the eutectic effect, while the hydration temperature and HHV of high-strength mass concrete can be decreased through the use of the PCM. A close relationship was found between the hydration temperature and autogenous shrinkage: the higher the HHV, the greater the ultimate autogenous shrinkage.

• Korean Journal of Health Education and Promotion
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• 제27권1호
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• pp.21-34
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• 2010

Objectives: The objective of this study was to investigate risk factors for falls in the elderly by life-cycle. Methods: This study used the data on 435 male and female elderly generated from a survey taken at 21 Welfare Centers for the Elderly in Seoul. The incidence of demographic characteristics, physical changes brought about with ageing, health-related behavior, chronic diseases, and environmental characteristics on falls in the elderly was analyzed. Hierarchical Logistic Regression analysis was also conducted to investigate the incidence by life-cycle (early-mid-late stage) and the results were used for predicting falls. Results: The incidence of risk factors on falls varied across life-cycle. Among the elderly in the early (ages from 65 through 74), marital status, the existence of a companion, the quality of sleep, the chronic diseases, and the condition of the bathroom floor were found to be related to falls. Among those in the mid-stage (ages from 75 through 84), sex, marital status, the existence of a companion, hearing capacity, sense of balancing, chronic diseases, the exclusive use of rooms, and the side bar with bath tub were found to affect falls. Finally, for the elderly in their late stage (85 years of age and older), drinking and vision were found to be related to falls. Conclusion: The incidence of risk factors on falls was found to vary according the stage in the elderly. A key implication of this finding is that falls prevention programs and interventions must be catered to specific age sub-groups.

• Fisheries and Aquatic Sciences
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• 제24권1호
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• pp.53-62
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• 2021

Gindai (Pristipomoides zonatus) is one of six snappers in a management complex called the Deep 7 of the Hawaiian Islands. Little is known about its life history and a preliminary analysis of otolith thin sections indicated the species may exhibit moderate growth with a lifespan approaching 40 years. Preliminary age estimates from the previous study were reinvestigated using the same otolith sections in an attempt to validate those ages with bomb radiocarbon (¹⁴C) dating. From the misalignment of birth years for the otolith ¹⁴C measurements with regional references - the post-peak bomb ¹⁴C decline period - it was concluded that previous ages were inflated from overcounting of the earliest growth zone structure in otolith sections. The oldest gindai was re-aged to 26 years once the age reading was adjusted for early overcounting, 13 years younger than the original estimate of 39 years for this fish. In general, the earliest otolith growth of gindai was massive and complicated by numerous subannual checks. The approach of lumping the early growth structures was supported by the alignment of ¹⁴C measurements from otolith core material (first year of growth). The result was greater consistency of calculated birthdates with the ¹⁴C decline reference, along with minor offsets that may indicate age estimation was imprecise by a few years for some individuals. The revised von Bertalanffy growth function applied to the validated age-at-length estimates revealed more rapid growth (k = 0.378 cf. 0.113) and a lifespan of approximately 30 years. The findings presented here are a case study of how the bomb ¹⁴C decline period can be used as a tool in the refinement of age reading protocols.

• Journal of Korean Academy of Nursing
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• 제36권1호
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• pp.45-54
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• 2006

Purpose: The purpose of this study was to explore Korean mothers' experiences of caregiving for their adult children with schizophrenia. Method: A iterative descriptive qualitative research design was used to understand and explain the caregiving experience from the perspective of mothers. The data were collected by individual in-depth interviews and one focus group interview from 11 mothers. The ages of the participants ranged from 50 to 60 years old and the ages of their sick children ranged from late 20s to early 40s, Results: Three major themes were identified from qualitative thematic analysis: (a) 'emotional debris from the disease,' (b) 'the disease that makes mothers dumb' (c) 'space of rational reason,' Conclusions: This study would provide health care professionals insights in establishing intervention for mothers by deeply understanding the process of recognition and acceptance of their children with schizophrenia.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
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• pp.629-634
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• 2001

This study is to characterize the material property of early age high performance concrete emphasizing compressive strength using nondestructive testing methods. Three high performance concrete slabs of 600, 850 and 1100kg/$cm^{2}$ compressive strengths were prepared together with cylinders from same batches. Cylinder tests were peformed at the ages of 7, 14, 21 and 28 days after pouring. Using the impact echo method, the compression wave velocities were obtained based on different high performance concrete ages and compressive strengths. The equation to obtain the compressive strengths of high performance concrete has been developed using the obtained compression wave velocities. Using the SASW (spectral analysis of surface wave) method, the equation have also been developed to obtain the compressive strengths of high performance concrete based on the surface wave velocities.

• Proceedings of the Korea Concrete Institute Conference
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.569-574
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• 2002

Generally, the limestone powder is known to have some advantages in rheology of fresh concrete, resistance of material separation, and enhancement of strength at early ages. Recently, great attention is being paid to limestone blended cements in the manufacture of concrete, especially in the countries of Europe. The purpose of the present study is to establish the mechanical and durable properties of concrete containing slag and limestone powder. In this paper, the chloride ion penetration test, rapid carbonation test and rapid freezing-thawing test is carried out to study durability of concrete with various content of limestone powder. Futhermore, the strength of concrete is evaluated with various ages.