• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.685-688
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• 2006

As the concrete structure being large-sized and/or high-strengthened, the control of the hydration and curing temperature is made much account. This study, analysing the concrete temperature history from cylindric specimen and mock-up structures, investigates the effect of the early age curing condition and the optimum method of curing temperature control on mass concrete.

• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.21.1-21.12
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• 2020

The aim of this article was to review age-dependent clinical recommendations for appropriate root canal instrumentation techniques. A comprehensive narrative review of canal morphology, the structural characteristics of dentin, and endodontic outcomes at different ages was undertaken instead of a systematic review. An electronic literature search was carried out, including the Medline (Ovid), PubMed, and Web of Science databases. The searches used controlled vocabulary and free-text terms, as follows: 'age-related root canal treatment,' 'age-related instrumentation,' 'age-related chemo-mechanical preparation,' 'age-related endodontic clinical recommendations,' 'root canal instrumentation at different ages,' 'geriatric root canal treatment,' and 'pediatric root canal treatment.' Due to the lack of literature with practical age-based clinical recommendations for an appropriate root canal instrumentation technique, a narrative review was conducted to suggest a clinical algorithm for choosing the most appropriate instrumentation technique during root canal treatment. Based on the evidence found through the narrative review, an age-related clinical algorithm for choosing appropriate instrumentation during root canal treatment was proposed. Age affects the morphology of the root canal system and the structural characteristics of dentin. The clinician's awareness of root canal morphology and dentin characteristics can influence the choice of instruments for root canal treatment.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.1
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• pp.71-79
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• 2021

This study investigates the capital structure policy among Indonesian public companies. Previous studies suggest that capital structure policy could follow either static or dynamic behavior. The sample data used in this study was companies in the manufacturing sector, divided into three sub-sectors: the basic and chemical industry, miscellaneous industry, and the consumer goods industry. This study uses panel data from 2010 to 2018, with the Generalized Least Square (GLS) method and compared whether the fixed effect model is better than the common effect model. The results show that the dynamic and non-linear model tests can explain the capital structure determinants than the static and linear models. The dynamic model shows that the capital structure of a certain year is influenced by the capital structure of the previous year. The findings indicate that the company performs some adjustments in its capital structure policy by referring to the previous debt ratio, which implies support to the trade-off theory (TOT). The study also shows that profitability, tangible assets, size, and age explain the variation of capital structure policy. The patterns on the dynamic and non-linear confirm that capital structure runs in a nonlinear pattern, based on the sector, company condition, and the dynamic environment.

• Economic and Environmental Geology
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• v.6 no.4
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• pp.201-216
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• 1973

Being believed thus far to be distributed in the wide areas in the vicinity of Seoul, the capital city of Korea, the Yonchon System in its type locality in Yonchon-gun from which the name derived was never previously traced down or correlated to the Precambrian metamorphic complex in Seoul area where the present study was carried out. Due to in accessibility to Yonchon area, the writer also could not trace the system down to the area studied so as to correlate them. The present study endeavored to differentiate general stratigraphy and interprete the structure of the metamorphic complex in the area. In spite of the complexity of structure and rapid changes in lithofacies of the complex, it was succeeded to find out the key bed by which the stratigraphy and structure of the area could be straightened out. The keybeds were the Buchon limestone bed in the western parts of the area; Daisongri quartzite bed cropped out in the southeastern area; Jangrak quartzite bed scattered in the several localities in the northwest, southwest, and eastern parts of the area; and Earn quartzite bed isolated in the eastern part of the area. These keybeds together with the broad regional structure made it possible to differentiated the Precambrian rocks in ascending order into the Kyonggi metamorphic complex, Jangrak group and Chunsung group which are in clinounconformable relation, and the first complex were again separated in ascending order into Buchon, Sihung, and Yangpyong metermorphic groups. Althcugh it has being vaguely called as the Yonchon system thus far, the Kyonggi metamorphic complex have never been studied before. The complex might, however, belong to early to early-middle Precambrian age. The Jangrak and Chunsung group were correlated to the Sangwon system in North Korea by the writer (1972), but it became apparent that the rocks of the groups have different lithology and highly metamorphosd than those of the Sangwon system which has thick sequence of limestone and slightly metamorphosed. Being deposited in the margin of the basin, it is natural that the groups poccess terrestrial sediments rather than limestone, yet no explanation is at hand as to what was the cause of bringing such difference in grade of metamorphism. Thus the writer attempted to correlate the both groups to those of pre-Sangwon and post-Yonchon which might be middle to early-late Precambrian time. Judging from difference in grade of deformation and unconformity between the Kyonggi metamorphic complex, Jangrak group, and Chunsung group, three stages of orogeny were established: the Kyonggi, Jangrak orogenies, and Chunsung disturbance toward younger age. It is rather astonishing to point out that the structure of these Precambrian formations. was not effected by Daebo orogeny of Jurassic age. The post-tectonic block faulting was accompanied by these orogenies, and in consequence NNE and N-S trending faults were originated. These faulting were intermittented and repeated until Daebo orogeny at which granites intruded along these faults. The manifestation of alignment of these faults is indicated by the parallel and straight linear development of valleys and streams in the Kyonggi Massifland.

• Korean Journal of Environment and Ecology
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• v.30 no.4
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• pp.783-792
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• 2016

The purpose of this study is to investigate the characteristics of the vegetation structure and the location environment of Albizzia kalkora (AK) growing in Mt. Yudal located in Mokpo city and in the nearby islands. The AK community in Mt. Yudal in Mokpo city (Community I) is located in a region which is relatively high above the sea level. The average age of the major kinds of trees found in the region is about 30 years. The vegetation structure in the community shows an early stage of vegetation development due to continued disturbance. In Community IV, on the sandy soil in the flatland near the seashores, the average age of the major kinds of trees is about 9 years. In this community, a pure forest is presumed to have been formed in a poor environment which is artificially disturbed in relatively recent times even as AK with its strong adoptability was introduced into the region. In other communities (II, III), the vegetation state shows a competition between AK and deciduous oak trees, and the average age of the major kinds of trees is about 13 to 30 years. AK communities with a better developed vegetation structure are located on the higher steep slopes near the seashore. In the early stage of vegetation development, the forest floor received more effective light for photosynthesis, and thus more seedlings of AK emerged and grew. The probability of AK appearing in the damaged or sterile soil near the seashore was high because of its strong adaptability. However, as the vegetation structure developed further and the soil fertility increased, the domination of AK in the vegetation structure decreased as deciduous oak trees won the competition with AK.

• Korean Journal of Community Nutrition
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• v.17 no.1
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• pp.109-118
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• 2012

This study was conducted to characterize changes in the meal structure of Korean children in terms of temporal and spatial dimensions. The data of 1,891 and 1,627 school-aged children and adolescents extracted respectively from the 1998 and 2009 Korea National Health and Nutrition Examination Surveys were analyzed by gender, age group, and residential area. From 1998 to 2009, the total eating events increased from 4.3 to 4.6 (p = 0.001); the average number of meal intake decreased from 2.8 to 2.7 (p < 0.001) while that of snack intake increased from 1.5 to 1.9 (p < 0.001). The prevalence of "3 meals a day" pattern tended to decrease while that of "2 meals a day" pattern increased over the years. Especially, the "2 meals a day" pattern with "lunch + dinner" increased from 13% in 1998 to 20% in 2009. The percentage of eating breakfast or dinner at home decreased over the years. These results indicate that over the last decade, "destructuration" occurred in Korean children's meal structure in terms of temporal and spatial dimensions. Especially, such alteration was more distinctive in male than female and in the high school-aged group than the elementary or middle school-aged groups. Overall, the difference of meal structure between genders and residential areas became smaller while the difference among age groups became larger over the years.

• Korean Journal of Plant Resources
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• v.11 no.3
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• pp.345-352
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• 1998

A Korean endemic and evergreen small tree ' Dendropanax morbifera $L_{EV}$.(Araliaceae)' is a component of evergreen forest and mainly idstributein sourthern region and islands in Korea. A local population of D. morbifera which is located between evergreen and deciduous forest within 50m x 50m quadrate was investigated to ascertain the change of population structure, emergence and growth dynamics of seedlings and saplings, and pattern of spatial distribution by the temproal and spatial expansion of population . The result of analysis of population structure by Importnace Value(IV), evergreen forest showed a high species diversity of evergreen tree species such as Cinnamomum japonicum, Machilus japonica, Neolitsea serica, Daphniphyllum macropodum, Ligustrum japonicum, and etc, in middle and under story than in upper story where Camelia japonica and Quercus acuta were dominant. And in conterminous deciduous fores, the major component of evergreen forest in this region, Camellia japonica, Quercus acuta, evergreen tree of Lauraceae and etc. were abundant in only under story. IV of D. morbifera differed from among three story. In comparative analysis of emergence and growth dynamics of D. morbifera seedlings and saplings between evergreen and deciduous forest, emergece and density of seedlings were significantly greater in evergreen than in deciduous forest, and growth of height and basal diameter of seedlings and saplings were slightly larger in evergreen than in deciduous forest. The spatial distribution patterns by Moristia's index mapping of indivuduals using a lattice method of XY axis within this population showed that seedlings(age up to 2 years) and saplings (age>2 years and height<1m) both evergreen and deciduous forest were more or less aggregated apart from mature trees, and thougth intermediate trees(height>1m and dbh<10cm) had a aggregated distribution pattern, mature trees(dbh>10cm were uniform. In conclusion , the expansion of D. morbfera population from evergreen to deciduous forest accompanied with a mumber of evergreen woody species, and also, emergence and recruitment, and growth of seedlings were greatly influenced moisture and canopy by around community structure.

• Journal of Korean Society of Forest Science
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• v.84 no.4
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• pp.437-446
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• 1995

This study was carried out to estimate the Korean Pine stand structure such as coefficient of variation of mean DBH, number of trees and volume per ha by Weibull distribution for each age class from I to V, based on photo measurement and timber cursing in Kangwon National University Experimental Forests. The results were summarized as follows: 1) Coefficient of variation of mean DBH for each age class from I to V, which was obtained by converting DBH estimated from crown diameter by photo measurement into quadratic mean DBH, was estimated as 28.88%, 24.13%, 23.29%, 20.27%, and 18.79%, respectively. 2) Number of trees per ha of each age class by Weibull distribution was obtained as 2875, 2100, 1875, 800, and 325, respectively. 3) Volume per ha of each age class was estimated as $22.9m^3$, $66.8m^3$, $101.3m^3$, $209.6m^3$, and $266.8m^3$, respectively. 4) Therefore, aerial photographs will be helpful to estimate the stand structure effectively.

• Management & Information Systems Review
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• v.37 no.1
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• pp.123-138
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• 2018

In this paper, we use panel dataset from Korean linked worker-firm to analyse the effects of the workforce age structure on the productivity or labor costs. We measure 'labor productivity' as added value per capita, 'cost of labor' as labor cost per capita and estimate a dynamic panel model to study the effects of the workforce age structure on the productivity or labor costs. Empirical analysis results show that the workforce age structure is positively related to productivity and labor costs, but only up to the aged of 35-39. That is, we find that an increase in the proportion of younger workers or elder workers rather than the aged 35-39 has a negative effect on productivity and labor cost. In particular, the difference between the estimation coefficient of productivity and labor cost when the share of workers aged 50 or older is increased instead of the aged 35-39 is higher than the difference between the estimation coefficient of productivity and labor cost when the share of workers aged 30 or younger is increased instead of the aged 35-39. Our results exhibit that it is reasonable for firms to worry about declining productivity of elderly workers, whereas firms already used older workers efficiently, such as by adjusting their labor costs.

• Journal of Korean Physical Therapy Science
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• v.6 no.1
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• pp.931-942
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• 1999

The aim of this research is to grasp the relation between lumbago incidence rate and research hypothesis in the effects of sex life of the middle-aged couples in Taejon area upon lumbago. And so, this writer had questionaired the 400 middle-aged couples in five gus, Taejon megalopolis -Jung-gu, Seo-gu, Dong-gu, Yuseong-gu, and Taedeok-gu - from April 21, 1998 to May 10, 1998. Of them, total 209 question papers were drawn back; male 102, female 107. Analysis of the data is as follows. 1. 145(69.37%) subjects of total 209 had experience in lumbago after their sexual lives. 2. In the number of sex life a week, one or two times of lumbago incidence rate were the most rate as 41.55% and each other had a statistically significant relation (P 0.01). 3. In age and lumbago incidence rate, their thirties was 37.75% and each other had a significant relation (P 0.05). 4. In weight and lumbago incidence rate, the level of $50kg{\sim}60kg$ was highest and each other didn't have a significant relation (P 0.05). 5. In the mean time of sexual life, the period of $11{\sim}20$ minutes was 29.47% and each other had a significant relation (P 0.01). 6. In week time zone of sexual life and lumbago incidence rate, midnight was the highest rate, 36.23% and each other didn't have a significant relation (P 0.05). 7. In the lumbago incidence rate according to bedroom structure of sexual life, a bed was 38.17% and each other had a significant relation (P 0.05). 8. In the lumbago incidence rate according to sexual posture, a normal position showed the highest rate, 46.12% and each other didn't have a significant relation (P 0.05). Putting the abovesaid results together, lumbago has relation to the number of sex life a week, age, the mean time of sexual life, and bedroom structure of sexual life. Therefore, it is thought that it is necessary that middle-aged couples periodically study the educational programs to make an education for lumbago prevention, etc. the key points.