• Management & Information Systems Review
• /
• v.37 no.1
• /
• pp.123-138
• /
• 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 the Korea institute for structural maintenance and inspection
• /
• v.21 no.4
• /
• pp.53-60
• /
• 2017

Fly ash(FA) which is a byproduct in the coal combustion in thermal power plant contributes to pore structure densification due to pozzolanic reaction, and this leads to long-term strength development and excellent resistance to chloride penetration. In the work, compressive strength and chloride resistance in OPC(Ordinary Portland Cement) and FA-based concrete are evaluated, and the relationships are investigated considering ages. For the work, 3 different W/B (Water to Binder) ratios of 37%, 42%, and 47% are prepared, and 3 substitution ratio of fly ash(0%, 30%, and 50%) are considered as well. At the age of 28 days and 180 days, test results of compressive strength, diffusion coefficients based on Tang's method, and passed charges referred to ASTM C 1202 and KS F 2711 are obtained. With increasing replacement ratio of FA and decreasing W/B, the resistances to chlorides(diffusion coefficient and passed charge) are improved, and the results at the age of 180 days decrease to only 15% level at the age of 28 days due to pozzolanic reaction in FA 50 mixture, which shows that resistance to chloride is much dependent on age effect than strength development. After 180 days, more clear linear relationships are observed between strength and resistance to chloride.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.4
• /
• pp.941-950
• /
• 2021

This study was conducted to identify the factors affecting the health-promoting lifestyle of the school-age obese children. Method: Data Collection for this study was conducted form July 20 to August 2, 2019 using a structured questionnaire. We analyzed the collected data by frequency, percentage, ANOVA, t-test, Pearson's Correlation Coefficient, and Multiple Regression Analysis. Results: The factors affecting the health-promoting lifestyle of the subjects, multiple regression analysis results showed that Dietary Self-Efficacy(𝛽=.406, p=.001), Physical Activity Self-Efficacy(𝛽=.245, p=.038), Furthermore, the F statistics for the fitness of the estimated regression model were 6.34(p<.001), which was significant. The explanatory power was 24.2%. Conclusion: The results of this study showed that Dietary Self-Efficacy and Physical Activity Self-Efficacy of the school-age obese children was the most influential factor on health-promoting lifestyle. Consequently, the results of this study suggest that it is necessary to find ways to improve Dietary Self-Efficacy and Physical Activity Self-Efficacy in order to improve health-promoting lifestyle of nurses, and it is considered to be useful as basic data for developing intervention programs to improve health-promoting lifestyle.

• Journal of the Korean Society of Radiology
• /
• v.14 no.7
• /
• pp.871-879
• /
• 2020

The purpose of this study was to analysis the correlation between kidneys function indicators and these size in ultrasonography. A total of 170 (male:86, female:84) patients of sex and age groups were examined by abdominal ultrasonography. The patients classified as those in their 20's, 30's, 40's, and over 50's. We measured the length, width, and cross-sectional height of the kidneys twice. At this time, the length of these were measured from the maximum upper to the maximum lower pole and the widest width in the same ultrasonography was measured to obtain the cross-sectional area. Other relevant indicators included body surface area, serum creatinine, glomerular filtration rate (GFR), MDRD (Modification of diet in renal disease) and C-G (Cockcroft-Gault). Significant comparisons of differences between relevant factors by age groups and sex were conducted with a one-way distribution analysis. Correlation analysis was also performed between relevant factors by using Pearson and Spearman correlation coefficient. It was defined as meaningful when the p-value was less than 0.05. As a result, the length, the width, and the cross-sectional area of kidneys were correlated with GFR, C-G, MDRD. Therefore, it is expected that the accuracy of diagnosis of kidneys disease will be increased if the relevant indicators are evaluated together rather than measuring only length of these in ultrasonography.

• Animal Bioscience
• /
• v.36 no.6
• /
• pp.899-907
• /
• 2023

Objective: The better understanding of laying pattern of birds is crucial for developing breed-specific proper breeding scheme and management. Methods: Daily egg production until 50 wk of age of six chicken breeds including one layer (White Leghorn, WL), three dual-purpose (Rhode Island Red, RIR; Columbian Plymouth Rock, CR; and Barred Plymouth Rock, BR), one synthetic dwarf (DY), and one indigenous (Beijing-You Chicken, BYC) were used to characterize their clutch traits and egg production. The age at first egg, egg number, average and maximum clutch length, pause length, and number of clutches and pauses were calculated accordingly. Results: The egg number and average clutch length in WL, RIR, CR, and BR were higher than those in DY and BYC (p<0.01). The numbers of clutches and pauses, and pause length in WL, RIR, CR, and BR were lower than those in DY and BYC (p<0.01). The coefficient variations of clutch length in WL, RIR, CR, and BR (57.66%, 66.49%, 64.22%, and 55.35%, respectively) were higher than DY (41.84%) and BYC (36.29%), while the coefficient variations of egg number in WL, RIR, CR, and BR (9.10%, 9.97%, 10.82%, and 9.92%) were lower than DY (15.84%) and BYC (16.85%). The clutch length was positively correlated with egg number (r = 0.51 to 0.66; p<0.01), but not correlated with age at first egg in all breeds. Conclusion: The six breeds showed significant different clutch and egg production traits. Due to the selection history, the high and median productive layer breeds had higher clutch length than those of the less productive indigenous BYC. The clutch length is a proper selection criterion for further progress in egg production. The age at first egg, which is independent of clutch traits, is especially encouraged to be improved by selection in the BYC breed.

• Asian-Australasian Journal of Animal Sciences
• /
• v.11 no.4
• /
• pp.363-367
• /
• 1998

This study has objectives of to estimate the genetic and phenotypic trend for growth in a closed herd of Landrace $\times$ desi crossbreds. The possibility of early selection of boars was also investigated in order to reduce generation interval and thus, to enhance response per year in selection programmes. The data originated from Livestock Production Research (Pigs), Indian Veterinary Research Institute (IVRI), Izatnagar (UP), India - a unit of All India Coordinated research Project on Pigs (AICRP on Pigs). Data consisted of 891 crossbred piglets, progeny of 29 boars. The piglets were born in 132 parities of 72 sows between 8 years from 1987 to 1994. Records on weight at birth, at 2 weeks interval upto 8 weeks of age (Wl, W2, ${\cdots}\;{\cdots}$ W8) and at 16th week (W16) were used in this investigation. BLLTP estimates of the sires were computed. Breeding value of each sire was estimated as twice of sire and sire group solutions. Phenotypic trend was estimated as regression of weight performance on year. Genetic trend was computed by estimating regression of breeding value of sires on time. Average body weights ranged from 0.92 kg (W1) to 18.95 kg (W16) and showed a continuous increase over age. Heritabilities of the weight at 4th and 6th week were medium (0.29 and 0.14). Rest of the weights were highly heritable. The product moment and rank, both correlations were high between breeding value for W6 and W16 (0.68 and 0.70). This shows that sire selection for W6 can be successfully implemented in order to achieve sufficient genetic improvement in growth. Phenotypic trend was positive at all ages. The phenotypic regression coefficient ranged from 0.02 kg at birth to 0.40 kg at 16 weeks. Genetic trend was also positive. The regression coefficients of average breeding value of sires on time showed a range of 1.471 kg (0.021 to 1.492 kg) for different weights. These coefficients were significant and higher than their corresponding phenotypic regression coefficient.

• Computers and Concrete
• /
• v.21 no.3
• /
• pp.279-289
• /
• 2018

Hydration heat and thermal induced cracking have always been a fatal problem for massive concrete structures. In order to study a massive reinforced concrete wall of a storage tank for liquefied natural gas (LNG) during its construction, two mock-ups of $0.8m{\times}0.8m{\times}0.8m$ without and with metal corrugated pipes were designed based on the actual wall construction plan. Temperature distribution and strain development of both mock-ups were measured and compared inside and on the surface of them. Meanwhile, time-dependent thermal and mechanical properties of the concrete were tested standardly and introduced into the finite-element (FE) software with a proposed hydration degree model. According to the comparison results, the FE simulation of temperature field agreed well with the measured data. Besides, the maximum temperature rise was slightly higher and the shrinkage was generally larger in the mock-up without pipes, indicating that corrugated pipes could reduce concrete temperature and decrease shrinkage of surrounding concrete. In addition, the cooling rate decreased approximately linearly with the reduction of heat transfer coefficient h, implying that a target cooling curve can be achieved by calculating a desired coefficient h. Moreover, the maximum cooling rate did not necessarily decrease with the extension of demoulding time. It is better to remove the formwork at least after 116 hours after concrete casting, which promises lower risk of thermal cracking of early-age concrete.

• The Journal of Korean Medicine
• /
• v.29 no.2
• /
• pp.60-70
• /
• 2008

Objectives: The aim of the present investigation was to determine whether the finger photoplethysmography (PPG) of the young will become analogous to those of the old when the PPG harmonic components in the young decrease. Methods: The PPG was measured in 46 old men (21 males and 25 females) over the age of 60 years and 10 young men (5 males and 5 females). We acquired the representative pulse waveform of old men by averaging the PPG waveforms measured in the old men. after the PPG harmonic components in the young men were diminished with notch filtering, we compared the representative pulse waveform of old men and those of the young men. Results: The PPG waveform of the young males became analogous to the representative pulse waveform of the old as the PPG harmonic components in the young were diminished with notch filtering. Especially after the second harmonic component in the young was diminished with notch filtering, increase of the Pearson's correlation coefficient was prominent. On the other hand, the Pearson's correlation coefficient between the PPG waveforms of the young females and that of the old deceased after the second harmonic component diminished in the young. Conclusions: Decrease of the second harmonic component may be a precondition of typical age-related change of the pulse waveform in the healthy male.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.1
• /
• pp.382-387
• /
• 2017

This paper analyzes the specialization factors for greenhouse-grown horticultural crops and location quotient. We derived the location quotient of two crops from the Agricultural Census in 2000, 2005, and 2010. The location quotient shows that specialization factors for spinach and lettuce became more concentrated. This means that cultivation of vegetables lean too much towards specialized regions. Implementation policies based on the level of specialization is expected to more efficiently improve the competitiveness of regional agriculture. The logit analysis showed that GRDP, age, education, average employee, and ratio of computer use had a significant impact on specialization of spinach. GRDP, age, and education negatively affected the specialization coefficient of spinach. However, average employee, and ratio of computer use positively affected the specialization coefficient of spinach. Based on these results, we set up the policy tools specializing the regional location quotient.

• Korean Journal of Veterinary Service
• /
• v.36 no.1
• /
• pp.15-21
• /
• 2013

Three serotypes (O+A+Asia1 type) of the foot-and-mouth disease (FMD) vaccine were injected into cloven-hoofed animals in Korea after the nationwide spread of FMD at the end of 2010. This study was conducted to investigate FMD antibody development after FMD vaccination, and to determine whether there was a significant correlation between the antibody titer of the sow and the antibody titer of the growing pigs. The antibody titer (percentage inhibition [PI] titer) of the sow (gilt) after FMD vaccination was maintained at a level higher than 50 (P<0.05) for 5 months. A higher PI titer for the 1-month-old growing pigs corresponded with greater inhibition of the PI titer of the vaccinated growing pigs (P<0.05). A negative correlation (P<0.05) between the PI titer of the 1-month-old growing pigs and the PI titer of 3-month-old growing pigs, 4-month-old growing pigs after FMD vaccination at 2 months, 3months was identified, with a coefficient of determination ($R^2$) of 0.274. Thus the PI titer of the growing pigs was inhibited to a greater degree when vaccination was performed at 2 months of age than at 3 months. However, many other factors likely influence growing pigs' PI titer in addition to the PI titer of the sow and age at vaccination, given that the coefficient of determination was somewhat lower.