• Journal of Animal Science and Technology
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• v.44 no.2
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• pp.191-200
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• 2002

This study was conducted to estimate the effects of environmental factors on certain reproductive traits in Korean cattle on the basis of data from Korean Cattle Improvement Areas which were surveyed from 1986 to 1995. Results obtained were summarized as follows ; 1. Least square means of the reproductive traits estimated were 466.11${\pm}$5.72 days for age at 1st service, 480.10${\pm}$6.15 days for age at 1st conception, 742.79${\pm}$7.48 days for age at 1st calving, 64.97${\pm}$1.42 days for days at 1st service postpartum, 72.06${\pm}$1.73 days for days open, 355.93${\pm}$1.92days for calving interval, 285.38${\pm}$0.42 days for gestation length and 1.21${\pm}$0.02 days for number of services for conception, respectively. 2. The ranges of the least squares means for the districts were 447.62${\pm}$5.94-490.72${\pm}$5.94 days for age at 1st service, 464.27${\pm}$6.38-505.20${\pm}$6.39 days for age at 1st conception, 721.91${\pm}$7.85-772.75${\pm}$7.80 days for age at 1st calving, 62.27${\pm}$1.55-68.97${\pm}$1.74days for days at 1st service postpartum, 69.74${\pm}$1.97-74.36${\pm}$2.27days for days open, 352.71${\pm}$2.18-359.64${\pm}$2.09 days for calving interval, 284.52${\pm}$0.42-286.04${\pm}$0.47days for gestation length and 1.11${\pm}$0.02-1.30${\pm}$0.02 days for number of services for conception, respectively. 3. Age at 1st service was latest in the cows with Basic Register and tended to be earlier for the more advanced registers. The number of services per conception tended to increase for the more advanced registers. 4. Days at 1st service postpartum was longest in the 2nd parity and tended to be shorter with the advancement of parity. The number of services per conception tended to decrease with the advancement of parity. 5. As the calving year advances from 1987 to 1995, days at 1st service postpartum, days open and calving interval tended to be longer, and number of service per conception tended to increase. 6. Days at 1st service postpartum, days open and calving interval were shorter in the cows that calved in spring and summer than in the cows that calved in fall and winter. The number of services per conception was larger in the cows that cocalved in fall and winter than the cows that calved in spring and summer.

• Korean Journal of Animal Reproduction
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• v.22 no.4
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• pp.359-366
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• 1998

A survey was carried out to investigate the effect of the parity on reproductive traits of Hanwoo(Korean native cows). Data on the reproductive traits of 670 Korean native cows were collected from January, 1996 to December, 1997 and analyzed by the parity. The results obtained were summarized as follows; 1. The average ages at first breeding, first conception and first calving were 443.0, 457.0 and 746.6 days, respectively. 2. The average days to first estrus after calving was 70.1 days and it was shortest in the cows with more than 5 parities (60.4 days) and longest in the cows at 4th parity (79.7 days). 3. The average number of services per conception was 1.53 and it was fewer in the cows at 2nd paity (1.43), but more in the cows with more than 5 parities (1.73). 4. The average days to first conception after calving was 91.2 days and there was a trend that it was longer as the parity of cows increased(p＞0.05). 5. The average length of calving interval was 375.3 days and it was shortest in the cows at 2nd cows (370.8 days) and longest in the cows at 4th parity (395.2 days).

• Journal of the Korean Applied Science and Technology
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• v.14 no.2
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• pp.41-48
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• 1997

Separation of EPA and DHA from fish oil fatty acid ethyl ester (FAFE) by urea adductive crystallization method was carried out in the supercritical carbon dioxide (SC $CO_2$) as a solvent. Our results showed that SC $CO_2$ is a good candidate as a solvent in the urea adductive crystallization to separate FAFE by the number of unsaturated bonds. Compared to the separation process using methanol. SC $CO_2$ yielded better performance in the overall selectivity of EPA and DHA. The effect of process variables on separation of EPA and DHA was discussed in detailed. A hybrid technology of SC $CO_2$ fractionation and urea adductive crystallization with SC $CO_2$ was conformed as a viable process to separate and concentrate EPA and DHA from fish oil.

• Journal of Korean Academy of Nursing
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• v.15 no.1
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• pp.5-16
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• 1985

This study examined the effects of husband's supportive behavior reinforcement education on stress relief of primigravidas. The purpose was to reinforce husbands' supportive behavior and relieve primigravidas' stress. The purposes of this study were to determine lactors influencing Primigravidas' stress and the effect of husbands' supportive behavior reinforcement education on stress relief of primigravidas. The subjects, consisting of 140 primigravidas who registered or visited in three obstetrics and gynecology clinics in J city, were divided into at random experimental and control groups. Data were collectpe from April To July, 1984 through interviews during hospital visits, and by questionaires. The husbands' supportive behavior reinforcement education and the measurement tools were developed by the investigator from the literature and during pilot study: the instruments to measure primigravidas' stress and husbands' supportive behavior were tested for reliability and validity. Personality characteristisc were measured by Chestnuts' Stress Management instrument. T-test, ANOVA, ω², and Pearson Correlation were used in analysing the data to confirm the intensity of the influence and the relation between general characteristics and primigravidas' stress. Pearson correlation and Stepwise Multiple Regression were used to confirm the predictors of primigravidas' stress. Independent variables were compared by means of t-test and χ³-test to confirm significant discrepancy of experimental and control groups. T-test, paired t-test, pearson correlation were used in analyzing the data to confirm the effect of husband's supportive behavior reinforcement education on stress relief of primigravidas. The results of the study are summarized. Results from analyzing the effect of husbands' supportive behavior reinforcement education: There was no significant difference between the general characteristics of the experimental and control groups. And husbands' supportive behavior, personality, marital Satisfaction, natural abortion variables influenced at primigravidas' stress. A hypothetical test by comparative analysis of the measurement of primigravidas' stress and husbands' support behavior between the experimental and the control group before and after the experiment to confirm the effect of husbands' supportive behavior reinforcement education resulted in the following: The first hypothesis that husbands' supportive behavior reinforcement education will increase husbands' support behavior to relieve primigravidas' stress was supported. The second hypothesis that husbands' supportive behavior reinforcement education will relieve primigravidas' stress was supported. As a result, it u·as shown that husbands' supportive behavior reinforcement education relieved primigravidas' stress, and the hypotheses were supported. The third hypothesis that the higher the degree of husbands' supportive behavior, the lower the primigravidas' stress was supported. It was concluded that husbands' supportive behavior reinforcemen education increase husbands' supportive behavior and relieves Primigravidas' stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2020-2028
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• 2015

This study was conducted in order to identify factors influencing maternal-fetal attachment among pregnant women, considering the factors presented in Mercer's theory: Becoming a Mother(pregnancy stress, self-esteem, dyadic adjustment, sense of mastery, antepartum stress). The data was collected through structured questionnaires from 140 pregnant women who visited the obstetric clinic and public health centers in a metropolitan area to have prenatal tests from August 23th to November 25th 2014. The data were analyzed by SPSS 20 software using descriptive statistics, the t-test, ANOVA, the Pearson's correlation coefficients and a stepwise multiple regression. The results were as follows: Maternal-fetal attachment in the group of pregnant women under 30 years of age was significantly higher than that in the group of over the age of 31(t=2.79,p=.004). Primiparas had higher maternal-fetal attachment than multiparas(F=3.27, p=.041). There was a negative correlation between pregnancy stress(r=-0.22, p=.009) and maternal-fetal attachment. Self-esteem (r=0.45, p<.001), dyadic adjustment(r=0.42, p<.001), sense of mastery(r=0.24, p=.005) and maternal-fetal attachment were, however, positively correlated. It was found that self-esteem, dyadic adjustment and age were some of the factors influencing maternal-fetal attachment among pregnant women. These variables explained 26.1% of the variance in maternal-fetal attachment. Findings of this study indicate needs for comprehension and assessment of self-esteem and dyadic adjustment in pregnant women through prenatal tests. Also, the intervention programs to improve maternal-fetal attachment among older mothers should be developed and implemented.

• Child Health Nursing Research
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• v.20 no.4
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• pp.247-254
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• 2014

Purpose: Maternal-fetal attachment in a pregnant woman is important for her health and for her child's emotional stability. This study was done to identify the contribution of maternal fatigue, social support, and Taegyo to maternal-fetal attachment based on a survey of pregnant women. Methods: The study was a descriptive correlation study. Participants were 211 from two women's health clinic centers. Data were analyzed using t-test, ANOVA, Pearson correlation coefficients and stepwise multiple regression. Results: Mean scores for maternal-fetal attachment, Taegyo, maternal fatigue, and social support were 93.74 (range 25-125), 64.76 (17-85), 24.12 (10-40), and 54.43 (22-132), respectively. There were significant differences in maternal-fetal attachment according to parity, breast feeding experience, and putting prenatal education into practice. Multiple regression analysis showed that the key determinants of maternal-fetal attachment, were Taegyo (${\beta}$=.67), maternal fatigue (${\beta}$=.21), and social support (${\beta}$=.13), and these explained 55% of the total variance of attachment. Conclusion: The results suggest a need to encourage Taegyo in prenatal management program and provide methods for fatigue resolution and promotion of social support.

• Women's Health Nursing
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• v.4 no.2
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• pp.173-186
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• 1998

In this study, both the literary survey as well as empirical research has been executed to test the validity of the scales that measure the construct of self-monitoring scale could not be classified into five factors as Snyder suggested. Many other scholars (Briggs, Cheek and Buss, 1980) suggested 3 different classifications which was accepted by Snyder and Gangestad (1986). John, Cheek and Klohnen (1996) claimed a two-factor classification. As has been discussed, factor analysis is used to prove convergent validity within the factor and discriminant validity between the factors. However, depending on the researchers, many variations in classification of the factors were found and a lack of content and discriminant validity was found in the previous research findings. It is also important to note that Snyder's self-monitoring scale, did not factor-load at over 30 for all 25 items, regardless of how many factors could be classified. According to findings of this study, the self-monitoring scale neither classified as five, three or two factors nor factor loaded as hypothesized. It is also clear that Snyder's self-monitoring scale lack convergent validity as the sub-factors of the scale fail to prove its uni-dimensionality. The A self-monitoring scale not only fail to overcome the problems of Snyder's self-monitoring scale but even lost the attractiveness of the self-monitoring scale. In this study, it was also found that the A self-monitoring scale was not classified as hypothesized in either in a two or three-factor classification. It is, of course, not desirable to use any scale that lacks convergent and discriminant validity even though it has been widely used but also has held a great deal of influence on the field of social psychology. To overcome the shortcomings of Snyder's self-monitoring scale, Lennox and Wolfe(1984) suggested 13 items. This study 1. was dedicated to test the validity and reliability of the scale, in which we found that the data presented in validity as the two factors were classified and loaded as expected. Reliability was also proven by checking Cronbach's alpha for each factor and for the total items. In addition, a confirmatory factor analysis was executed for the 13 items using LISREL 8.12 program to confirm convergent validity in a two-factor classification. The model was fitting and sound ; however, the self-monitoring scale was unfitted and not validated. Thus, it is recommended to use not the original or the abbreviated self-monitoring scale but the 13 items in future studies. It should also be noted that items 7 and 13 should be removed to obtain better uni-dimensionality for the 13 items. These items loaded at over .30, too high for the two factors in the test results of factor analysis. In addition, it is necessary to double-check the cause of two-hold loading at over .30 for the two factors. It could be a problem caused by data or by the scale itself. Therefore, additional studies should follow to better clarify this matter.

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.1
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• pp.33-40
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• 2021

The objective of this work is to prove a possibility of void f illing through a carbonation f or the purpose of improving the quality of recycled aggregate. Carbonation can permanently immobilize CO2, which is a greenhouse gas, and thus provides additional benefit on environment. In this work, recycled fine aggregate was reacted using gaseous CO2 and supercritical CO2(scCO2) in a closed chamber, and the changes in physical properties of the recycled f ine aggregate bef ore and af ter carbonation were analyzed using the apparent density, skeletal density, pH, and FE-SEM measurements. Thereafter, a mortar specimen was prepared and a compressive strength was measured. According to the experimental results, it was found that the increase in the apparent density and the true density was higher by the reaction with scCO2, which was conducted at high temperature and high pressure compared to the reaction with gaseous CO2. In addition, the pH of the eluted water was found to have a larger initial decrease than that observed with samples from reaction by gaseous CO2. The shape and amount of calcium carbonate crystals were also found to be larger than that from gaseous CO2. The increase in compressive strength was the largest when using recycled fine aggregate reacted with scCO2. It was clear that quality improvement of recycled fine aggregate was higher with scCO2 than with gaseous CO2.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.12
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• pp.1421-1426
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• 2014

To improve the inherent safety of the sodium-cooled fast reactor (SFR), the supercritical $CO_2$ ($S-CO_2$) Brayton cycle is being considered as an alternative power conversion system to steam the Rankine cycle. In the $S-CO_2$ system, a PCHE (printed circuit heat exchanger) is being considered. In this type of heat exchangers, diffusion bonding is used for joining the thin plates. In this study, the diffusion bonding characteristics of various austenitic alloys were evaluated. The tensile properties were measured at temperatures starting from the room temperature up to $650^{\circ}C$. For the 316H and 347H types of stainless steel, the tensile ductility was well maintained up to $550^{\circ}C$. However, the Incoloy 800HT showed lower strength and ductility at all temperatures. The microstructure near the bond line was examined to understand the reason for the loss of ductility at high temperatures.

• Journal of Aerospace System Engineering
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• v.16 no.5
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• pp.17-25
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• 2022

The pintle injector has many advantages in the key characteristics of a liquid rocket engine, such as combustion stability, combustion efficiency, and wide range of comprehensive thrust control, design and manufacture, and test fired under supercritical conditions. The pintle injector is manufactured with a rectangular, single-row orifice for thrust control and production considerations. In order to verify the combustion performance of the pintle injector and its potential as a commercial injector, the combustion characteristics were analyzed by varying the TMR (Total Momentum Ratio) and BF (Blockage Factor). The result of the hot firing test showed that the heat flux increased as TMR increased, and it confirmed that the characteristic velocity efficiency was more affected by BF than TMR. Suppose a single-row pintle injector with efficiency characteristics insensitive to changes in TMR can achieve high efficiency at low fuel differential pressure conditions. In that case, the variable pintle injector's design flexibility can be increase.