• Proceedings of the KWS Conference
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• 2001.05a
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• pp.220-223
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• 2001

In this study, CT specimens were prepared hem ASTM SA516 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -l$0^{\circ}C$ and -l2$0^{\circ}C$ and in the range of stress ratio of 0.1, 0.3 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔK$_{th}$ in the early stage of fatigue crack growth ( Region I ) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da/dN - ΔK in Region II, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region H and the cryogenic-brittleness greatly affect a material with decreasing temperature.e.greatly affect a material with decreasing temperature.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2001.05a
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• pp.326-331
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• 2001

In this study. CT specimens were prepared from ASME SA5l6 which was used for pressure vessel plates for room and low temperature service. And we got the following characteristics from fatigue crack growth test carried out in the environment of room and low temperature at $25^{\circ}C$, -3$0^{\circ}C$, -6$0^{\circ}C$, -8$0^{\circ}C$, -10$0^{\circ}C$ and -12$0^{\circ}C$ in the range of stress ratio of 0.1 by means of opening mode displacement. At the constant stress ratio, the threshold stress intensity factor range ΔKsub/th/ in the early stage of fatigue crack growth ( Region I) and stress intensity factor range ΔK in the stable of fatigue crack growth ( Region II) was increased in proportion to descend temperature. It assumed that the fatigue resistance characteristics and fracture strength at low temperature is considerable higher than that of room temperature in the early stage and stable of fatigue crack growth region. The straight line slope relation of logarithm da.dN -ΔK in RegionII, that is, the fatigue crack growth exponent m increased with descending temperature at the constant stress ratio. It assumed that the fatigue crack growth rate da/dN is rapid in proportion to descend temperature in Region II and the cryogenic-brittleness greatly affect a material with decreasing temperature.

• Korean Journal of Animal Reproduction
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• v.20 no.4
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• pp.443-451
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• 1997

These studies were conducted to determine the sex of preimplantation Hanwoo embryos produced in vitro using polymerase chain reaction(PCR). Y chromosome specific and bovine speicific DNA primers were synthesized and tested for embryo sexing. Bovine IVF embryos were produced in TCM 199 and CR1aa medium, and classified by developmental stages on Day 7 to 9. The effects of developmental rates to bovine IVF blastocysts on sex ratio were also investigated using PCR methods. The results obtained in this study were as follows; 1. Developmental rates to blastocyst from IVM/IVF embryos in TCM 199 and CR1aa medium for 9 days were 23.5 and 30.2%, respectively, and there was significant difference between the media(P<0.05). 2. Male to female ratio of early, mid, expanded and hatching balstocyst produced on Day 7 were 0.7:1, 1.4:1, 2.2:1, and 2.5:1, respectively, and male embryos was significantly higher proportion in expanding and hatching blastocysts(P<0.01). 3. On Day 8, male to female ratio of early, mid, expanded and hatching blastocysts were 0.6:1, 1:1, 2.5:1, and 2.7:1, respectively. Both expanded and hatching blastocysts obtained a significantly higher proportion of males(P<0.01). 4. The male : female ratio of early, mid, expanded and hatching blastocyst produced on Day 9 was 0.6:1, 0.8:1, 1:1, and 2.2:1, respectively. Hatching blastocysts had a significantly higher ratio of males(P<0.01). The developmental rate of IVM/IVF embryos to blastocyst for 9 day culture was higher in CR1aa than that in TCM 199 medium. For the sex ratio by developmental stages of IVF embryos, male ratio was higher in expanded blastocyst but female in early blastocysts.

• Korean Journal of Health Education and Promotion
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• v.18 no.2
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• pp.65-82
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• 2001

The purpose of this study is to find out how well the middle school students are practicing the health promotion behaviors and the factors relating their health promotion behavior. Questionnaire survey on 922 middle school students attending 6 middle schools (three middle schools for each sex) located in Taegu City from the 7th through 19th of Feb. 2000 were conducted. The following were as follows; 1. The perceived health status is higher in male students than in female students(p〈0.01). And the ratio of the students' feeling that they are healthy becomes also high in proportion to their economic status, and their mothers' educational level, and their parents' interest in health(p〈0.01). The perceived importance of health is high in proportion to the students' economic status, and their parent's interest in health. 2. In case of the Health Locus of Control in Personality, the students with both parents have higher trend of inner control than the students with single mother or single father. The perceived self efficacy is significantly higher in male students than in female students(p〈0.01). And it becomes significantly high in-proportion to the students' economic status and their parents' educational level and interest in health(p〈0.01). It is also higher in the students who had no diseases. 3. In case of the perceived benefit of the health promotion behavior, the ratio of the students responding that it is high is higher in male students than in female students(p〈0.01). It also becomes high in proportion to the students' economic status, and their parent's educational level and interest in health(p〈0.01). The barriers of the health promotion behavior was found to have no variables that are related to itself. 4. According to the data from Multiple Regression of Analysis which has the health promotion behavior practice as a subordinate variable, in male students' case the degree of health promotion behavior practice becomes high in proportion to their parents' interest in health, and the perceived health status. Their degree of health promotion behavior practice is also in proportion to their perceived self efficacy and the perceived benefit of the health promotion behavior practice. But in case of the barriers of the health promotion behavior practice, the result is the opposite. As to the female students, their health behavior practice becomes high in proportion to their parents' interest in health. It also becomes high in proportion to the perceived health status, the understanding of the importance of the health, the perceived self efficacy and the perceived benefit of the health promotion behavior. But in case of the barriers of the health promotion behavior, it was the same as the male students' case.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.3
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• pp.197-204
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• 2021

In MBR, extracellular polymeric substance (EPS) is known as an important factor of fouling; soluble EPS (sEPS) affects internal contamination of membrane, and bound EPS (bEPS) affects the formation of the cake layer. The production of EPS changes according to the composition of influent, which affects fouling characteristics. Therefore, in this study, the effects of the F/M ratio on the sEPS concentration, bEPS content, and fouling were evaluated. The effects of F/M ratio on the amount and composition of EPS were confirmed by setting conditions that were very low or higher than the general F/M ratio of MBR, and the fouling occurrence characteristics were evaluated by filtration resistance distribution. As a result, it was found that the sEPS increased significantly with the increase of the F/M ratio. When the substrate was depleted, bEPS content decreased because bEPS was hydrolyzed into BAP and seemed to be used as a substrate. In contrast, when the substrate is sufficient, UAP (utilization-associated products) was rapidly generated in proportion with the consumption of the substrate. UAP has a relatively higher Protein/Carbohydrate ratio (P/C ratio) than BAP, and this means, it has a higher adhesive force to the membrane surface. As a result, UAP seems like causing fouling rather than BAP (biomass-associated products). Therefore, R_f (Resistance of internal contamination) increased rapidly with the increase of UAP, and R_c (Resistance of cake layer) increased with the accumulation of bEPS in proportion, and as a result, the fouling interval was shortened. According to this study, a high F/M ratio leads to an increment in UAP generation and accumulation of bEPS, and by these UAP and bEPS, membrane fouling is promoted.

• Journal of the Korean Society of Physical Medicine
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• v.18 no.4
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• pp.19-27
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• 2023

PURPOSE: This investigation in the study aimed to assess to determine proportion and susceptibility makers of sarcopenia in Korean younger female aged 30 to 39 years. METHODS: To address the complex sampling design of Korea National Health and Nutrition Examination Surveys, appropriate individual weights were incorporated into the analysis. The data employed a stratified, clustered, multistage probability sampling design. A total of 2,098 participants were enrolled and categorized into two groups based on their skeletal muscle mass index scores. One hundred and twenty-four individuals were placed in the sarcopenia group, while 2,024 were allocated to a normal group. The study examined various markers as variables, including age, height, weight, body mass index waist circumference, skeletal muscle mass index, systolic and diastolic blood pressure, fasting glucose, triglyceride, and total cholesterol levels, and smoking and drinking habits. RESULTS: The study found that proportion of sarcopenia in this population was 3.78% (CI: 2.89-4.94) in sarcopenia group and 96.22% (CI: 95.06-97.11) in normal with weighed values. Several susceptibilities including height, weight, BMI, waist circumference, diastolic blood pressure, and total cholesterol levels were risk factor for sarcopenia (p < .05), exhibited significant differences between the sarcopenia and normal groups. CONCLUSION: This investigation provides the proportion of sarcopenia and identifies relevant susceptibility markers among community dwelling younger women in Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.37-46
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• 2007

The service life of agricultural concrete structures is designed in about 30 to 100 years, but actual service lift is estimated in an average 18 years. Therefore, as the service life of the agricultural concrete structures increases, necessity of repair by aging from various environment condition exposure increases. This study was to determinate the optimum mix proportion of latex modified repair mortar and to improve the durability performance of agricultural concrete structures. The physical and mechanical tests of latex modified repair mortar were performed. Tests of flow, compressive strength, flexural strength and bond strength tests were conducted. Test results show that the optimum nex proportion of latex modified repair mortar, when used in 5% latex volume fraction (weight of cement), 1.5% antifoaming agent (weight of latex), 0.2% PVA fiber volume fraction, 1:2 (binder-sand ratio), 10% silica fume replacement ratio (weight of cement), could result in best performance for the repair of agricultural concrete structures.

• Journal of the Korean Society of Costume
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• v.57 no.10
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• pp.35-49
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• 2007

This study aims at strengthening the national competitiveness of Korea's clothing industry as it provides substantial information on type characteristics and body types for Chinese women and improves the fitness of clothing, considering human proportion in the production of clothing products for export to China. It divides the group by residental district and specific markets. It analyzes the part proportion of body types by each group. This selected specimen as 1,381 of Chinese women from 19 to 50 selected in random sampling in Shanghai and Beijing from 23th, June to 7th August in 2004. 1. Beijing women have long head length of 7.04 in proportion while Shanghai women have short head length of 7.14 in proportion. 2. For 19-24 years old women, head-to-height ratio (HHR) is 7.14, while 24-34 years old women and 35-50 years old women are 7.04 and 7.09 respectively.

• Journal of the Korean Society of Combustion
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• v.13 no.3
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• pp.9-16
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• 2008

In this study, a cylindrical constant volume combustion chamber is used to investigate the flow and combustion characteristics of methane-air homogeneous mixture under various initial charge pressure, excess air ratios and ignition times. The flame and burning speed, mean gas speed are calculated by numerical analysis to analyze the combustion characteristics. It is found that the mean gas velocity during combustion has the maximum value around 300 ms and then decreased gradually on the condition of 10000 ms, and that the combustion duration is shorten and flame speed and burning velocity have the highest value under the conditions of an excess air ratio 1.1, an initial charge pressure of 0.2 MPa and an ignition time of 300 ms in the present study. And, the initial pressure and burning speed are in inverse proportion, so that it is in agreement with Strehlow who presented that the initial pressure and burning speed are in inverse proportion when the burning speed is under 50cm/s.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.373-378
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• 2000

The objective of this study was to investigate the influence the influence of theoretical void ratio(T.V.R), grading of aggregate and curing method on the strength and water permeability of porous concrete, and the reduction proportion of water permeability by these factors. The results of the study showed that its strength and water permeability were greatly depended on the T.V.R and grading of aggregate, but didn't on the curing method. And, when the T.V.R and grading of aggregate were increased, the reduction proportion of water permeability was small. As the relation ship between its physical properties and non-destruction test values was very high, its use for the estimation of the physical properties will be useful.