• 한국임상수의학회지
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• 제14권2호
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• pp.287-296
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• 1997

Serial ultrasonographic examinations were daily performed on 8 bitches (5 Maltese and 3 Yorkshire terrier) from day 15 until parturition to determine the size of gestational structures. Gestational age was timed from the day of ovulation (day 0), which was estimated to occur when plasma progesterone concentration was first increased above 4.0 ng/ml. When the size of fetal and extra-fetal structures according to gestational age was measured, there was a difference between Maltese and Yorkshire terrier in extra-fetal structures (P<0.001), and no difference in fetal structrures (P<0.001). The correlations between the gestational age and the growth in fetal and extra-fetal structures were examined by regression analysis. The extra-fetal structure which showed high correlation from day 20 to 35 was inner chorionic cavity diameter in two breeds. The fetal structures which showed high correlation from day 36 until parturition was fetal head diameter in two breeds. In conclusions inner chorionic cavity diameter was the most accurate for estimation of gestational age and prediction of whelping day from day 20 to 35, and fetal head diameter from day 36 to parturitions respectively. Ultrasonography is very useful tool to evaluate the gestational age and to predict the whelping day in pet dogs.

• 산업기술연구
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• 제25권B호
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• pp.73-80
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• 2005

Durability of concrete structures is seriously compromised by cracking at early-age concretes, particularly in high-strength or high-performance concrete structures. Since early-age cracking is influenced by various factors that affect the hydration process, early-age shrinkage and stress/strain development, the behavior at early-age is highly complex and no rational methodologies for its control have yet been established. Concrete structures often present volumetrical changes particularly due to thermal and moisture related shrinkages. Volumetric instability is detrimental to the performance and durability of concrete structures because structural elements are usually restrained. These restrained shrinkages develope tensile stresses which often results in cracking in combination with the low fracture resistance of concrete. Early-age defects in high-performance concrete due to thermal and autogenous deformation shorten the life cycle of concrete structures. Thus, it is necessary to examine the behavior of early-age concrete at the stages of design and construction. The purpose of this study was to propose a shrinkage models of VES-LMC (very-early strength latex-modified concrete) at early-age considering thermal deformation and autogenous shrinkage.

• 한국임상수의학회지
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• 제21권2호
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• pp.143-148
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• 2004

Serial ultrasonographic examination was daily performed on 12 pregnant Shih-tzu bitches from day 15 until parturition to determine the size of gestational structures. Gestational age was timed from the day of ovulation (day 0), which was estimated to occur when plasma progesterone concentration was first increased above 4.0 ng/ml. Extra-fetal structures were measurable from days 17 to 46. Outer uterine diameter increased from $9.9{\pm}0.4$ mm (Mean${\pm}$SD) at day 20 to $44.3{\pm}0.8$ mm at day 46 and inner chorionic cavity diameter increased from $7.2{\pm}0.2$ mm at day 17 to $36.9{\pm}1.5$mm at day 41. Length of chorionic cavity or zonary placenta increased from $6.6{\pm}0.4$ mm at day 21 to $46.4{\pm}0.9$ mm at day 44. Of the extra-fetal structures, inner chorionic cavity diameter was the most accurate for estimation of gestational age until day 38. Fetal structures were measurable from days 23 to 60. Crown-rump length increased from $3.9{\pm}0.3$ mm at day 23 to $55.2{\pm}3.3$ mm at day 41, fetal body diameter increased from $7.9{\pm}0.6$ mm at day 32 to $47.8{\pm}2$ mm at day 60, and fetal head diameter increased from $6.3{\pm}1.1$ mm at day 29 to $25.6{\pm}0.2$ mm at day 60. Of the fetal structures, fetal head diameter was the most accurate for estimation of gestational age from day 38 until day 60.

• 한국임상수의학회지
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• 제25권6호
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• pp.501-505
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• 2008

Serial ultrasonographic examinations were performed on 9 Miniature Schnauzer bitches from day 15 of gestation until parturition to determine the ultrasonographic measurement of gestational structures. Ovulation was designated the day that plasma progesterone concentration exceeded 4.0 ng/ml (day 0). Extra-fetal structures were measured from day 17 or 18 to 60. Outer uterine diameter (OUD) increased from $6.50{\pm}1.06mm$ ($Mean{\pm}SD$) to $50.89{\pm}5.62mm$, inner chorionic cavity diameter (ICCD) increased from $2.10{\pm}0.15mm$ to $37.15{\pm}4.36mm$, and length of placenta (PL) increased from $7.50 {\pm}1.41mm$ to $40.62{\pm}3.27mm$. OUD and ICCD were significantly and linearly relative to gestational age especially through day 37, whereas PL was not significantly relative to gestational age. Of the extra-fetal structures, ICCD was the most accurate for estimation of gestational age before day 38 of gestation. Fetal structures increased at a linear rate to parturition. Fetal crown-rump length (CRL) increased from $2.55{\pm}0.07mm$ on day 22 to $85.25{\pm}9.89mm$ on day 48. Fetal head diameter (HD) increased from $3.43{\pm}0.64mm$ on day 27 to $25.06{\pm}0.41mm$ on day 63. Fetal body diameter (BD) increased from $ 5.96{\pm}0.84mm$ on day 30 to $43.76{\pm}3.36mm$ on day 63. Of the fetal structures, HD was the most accurate for estimation of gestational age after day 38 to parturition.

• Steel and Composite Structures
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• 제47권6호
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• pp.729-741
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• 2023

As the most popular shear connection in composite structures, mature concrete has been widely investigated by considering mechanical properties of stud connectors (SCs) embedded. To further enhance the fabrication efficiency of composite structures and solve the contradiction between construction progress and structural performance, it is required to analyze the shear performance of stud connections of composite structures with different concrete ages. 18 typical vertical push-out tests were carried out on stud shear connectors at concrete ages of 7 days, 14 days, and 28 days. Also, the effects of concrete age, stud spacing and stud diameter on the shear capacity, connection stiffness and failure mode of the connectors were studied. A new relationship expression of load-slip for SCs with various concrete ages was proposed. The existing design code for the SCs shear strength was evaluated according to the experimental data, and a more practical prediction equation for the shear capacity of SCs with different concrete ages was established. A great agreement was observed between the experimental and theoretical results, which can provide a reference for engineering practices.

• 대한가정학회지
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• 제41권1호
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• pp.39-58
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• 2003

This study investigated the effects of the householder's age as a proxy for the family life cycle stage variable and the householder's occupation on the household financial structures. Household financial structures are analyzed by the components of two financial statements(the income and expense statement and the balance sheet statement) and selected financial ratios. The data came from the 1998 Korean Household Panel Study. It was found that the age profiles of household finances such as household income, expenditure, savings and consumption rate, financial assets, real assets and home ownership, debt and net worth usually vary according the householder's occupation. The ratios of debt repayment and the liquidity ratios also vary in part as age changes for each occupational group.

• 한국구조물진단유지관리공학회 논문집
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• 제7권1호
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• pp.259-266
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• 2003

Recently, the premature corrosion for reinforced concrete structure exposed to chloride bring about a serious problem in concrete structures. Specially, the concrete structures of sea coast are exposed much to chloride which make rapid corrosion. Thus, construction activities and maintenances for marine facilities are more demanded than those for land structures. The results of this study have been analysed to identify the extent of chloride content and incidence of carbonation for construction age. After measuring chloride content in concrete, it was conclued that about 90% of all tests on concrete samples exceed the acceptable maximum limit to risk of chloride-induced carbonation. The carbonation rate coffnient by age of train structures in the east eatimated 6. 55, 4.76 grater than 3. 727. In the basis of this result, it is necessary to maintenance for the important train facilities with the regular tests of chloride and carbonation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2010년도 춘계 학술대회 제22권1호
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• pp.465-466
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• 2010

In this paper, an integrated system is proposed which can evaluate both the early-age properties and durability performance of concrete structures. This integrated system starts with a hydration model which considers both Portland cement hydration and chemical reactions of supplementary cementing materials (SCM). Based on the degree of hydration of cement and mineral admixtures, the amount of reaction products, the early age heat evolution, chemically bound water, porosity, the early age short-term mechanical behaviors, shrinkage and early-age creep are evaluated as a function of curing age and curing conditions. Furthermore, the durability aspect, such as carbonation of blended concrete and chloride attack, are evaluated considering both the material properties and surrounding environments. The prediction results are verified through experimental results.

• 한국전산구조공학회논문집
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• 제24권4호
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• pp.391-398
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• 2011

철근콘크리트 구조물은 타설 후 시간이 경과함에 따라 물리적인 요인과 화학적인 요인으로 인하여 열화가 진행된다. 열화된 구조물의 효율적인 구조해석을 수행하기 위하여 구조물의 거동과 밀접한 관련이 있는 중요열화변수를 정의하는 것은 필요하다. 본 연구에서는 경년열화된 철근콘크리트 전단벽의 중요변수를 분석하기 위하여 일계이차모멘트법을 이용하여 민감도해석을 수행하였다. 콘크리트의 경화현상을 고려하지 않을 경우 구조물의 열화성능이 과소평가될 수 있으므로 콘크리트의 경화에 따른 해석변수들의 민감도를 분석하였다. 열화된 전단벽에서 변수의 중요도는 토네이도 다이어그램으로 나타내었다.

• Asian-Australasian Journal of Animal Sciences
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• 제6권4호
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• pp.497-507
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• 1993

Four truncation selection schemes (SSs) were framed to predict and compare the age structures and genetic responses under the influence of various factor employing the scheme-specific algorithms. Two paths of selection, sires (bulls' sires) and dams (bulls' dams) to breed young bulls were considered. Among variable factors, four levels (0.3, 0.5, 0.7, 0.9) of precision of evaluation, five levels (0.0, 0.05, 0.10, 0.15, 0.20 genetic standard deviation) of genetic differences among age classes and 4 levels of proportions selected (for bulls' sire, 0.05, 0.10, 0.125, 0.25, and for bulls' dams 0.02, 0.04, 0.05, and 0.10) contemplated on both paths of selection. The number of age classes for bulls' dams and bulls' sires were 4 or 8 and 2 or 4, respectively. The stayability across age classes for bulls' dams was assumed to be 0.80 or 0.60. The candidates for selection for bulls' sires were equally distributed (0.5 or 0.25) across the age classes. The SS1 (selection on same proportions as candidates' distribution) revealed longest generation lengths and lowest yearly genetic responses. The average ages were youngest and yearly genetic responses were highest in SS4 (selection at each age-specific truncation point with the same average genetic superiority of selected parents across the ages) and followed by SS3 (selection at each agespecific truncation point with same predicted genetic values) and SS2 (selection at common truncation point on phenotypic values) in a population with overlapping generations. The results revealed the importance of choosing suitable selection scheme to acquire maximum yearly genetic responses especially when the genetic differences among age classes are large and the precision of evaluation is relatively low.