• Korean Journal of Animal Reproduction
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• v.3 no.1
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• pp.48-55
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• 1979

This experiment was conducted to investigate the effects of ovariectomy and estradiol benzoate administration on body growth and development of endocrine glands in female rats. One hundred and twenty female rats, 30 days old weighing 72.0${\pm}$3.0g, were divided into control and ovariectomized groups and divided again into two groups, treated and untreated with estradiol benzoate, respectively. Each group was composed of 30 rats. Hormone was injected every two week interval. The body weight was measured weekly from the beginning of treatment to 63 days after treatment and 6 rats per group were sacrificed at 7, 21, 35, 49 and 63 days after treatment for weight change of endocrine gland. The results obtained were as follows: 1. the changes in the body weight during the experimental period were not signifilcantly different between two groups, although the body weight of ovariectomized groups were heavier than that of control groups and the body weight of treated group with estradiol benzoate was heavier than that of untreated group. 2. The body lengths in all groups were increased proportionally to body weight until 63 days after treatment and there were not significantly different among the experimental groups. 3. The weight of hypophysis treated with estradial benzoate in ovariectomized groups was continuously increased in the whole period and was highly significant at 49 and 63 days after treatment as compared with those of untreated in ovariectomized group. 4. Adrenal gland weights of the control and ovariectomized group treated with estradiol benzoate were distinctly light at 21 days after treatment, but there were not significantly different among all groups at 35 days. Adrenal gland weight of ovariectomized groups was smaller than control groups at 49 days and untreated group in ovariectomized groups was considerably smaller than the other 3 groups at 63 days after treatment. 5. In control rats, the ovary weight treated group with estradiol benzoate was larger than the untreated group at 35 days after treatment, but was smaller than the untreated group after 49 days. 6. The weight of reproductive tract in ovariectomized groups were markedly smaller than control groups till 35 days after treatment. The growth of reproductive tract untreated in ovariectomized groups was almost completely depressed.

• Proceedings of the KSR Conference
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• 2009.05b
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• pp.311-320
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• 2009

Most advanced countries are researching to apply light weight materials far rolling stock because weight reduction for railway body derives cost-saving, energy-saving, and high-speed. Likewise, current Korea rolling stock field makes arduous effects of weight-reduction, miniaturization, and high-efficiency to achieve a high-speed railway. Aluminum becomes suitable material for these projects because it is much lighter than steel or stainless. Manufacturing the railway car body by using the Aluminum is increasing because Aluminum is not bringing the corrosion by unique oxidation-passivate. Aluminum extrusion profile far railway body requires a high mechanical property, accurate shape dimension, and stable quality because the railway body is composed with many different kinds of extruded profiles. Therefore, it is necessary to research about Aluminum precision-extrusion technology to maintain exit temperature and die load. The goal of this project is applying the Aluminum extrusion profile to next-generation railway car body by developing the Aluminum extrusion profile according to precision-extrusion technology which may maintain isothermal exit temperature.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.59-66
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• 2015

A new concept of an inorganic foaming process at low temperature was demonstrated for the production of inorganic thermal insulating materials with the properties of flexible light-weight, the advantages of organic-based thermal insulation material. The foaming process was proceeded by establishing a skeleton of the foam body by using inorganic fibrous sepiolite and aluminum silicate. A cavity was formed by the expansion of fibrous skeleton body, by the gas which was generated from foaming agent at low temperature. Then the multi-vesicular expanded perlite with low thermal conductivity was filled into the cavity in a skeleton of the foam body. Finally through these overall process, a new inorganic foamed body could be obtained at low temperature without the hot melting of inorganic materials. In order to achieve this object, various preparations such as fibrous sepiolite fibrillation process, heat treatment process of the fibrous slurry were needed, and the optimal compositional condition of slurry was required. The foam body produced showed the properties of flexible light-weight thermal insulation materials such as bulk density, yield strength, flexural strength, and high heat resistance.

• Proceedings of the KWS Conference
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• 2003.11a
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• pp.52-54
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• 2003

In automotive industry, light weight vehicle is one of issues because of air pollution. Therefore, automotive manufacturers have tried to apply light materials such as aluminum to car body. Welding aluminum using laser has some advantages good weld quality and high productivity. In this study, light emission which is generated in aluminum 6k21 welding with laser is measured using photodiodes. Analysis of relationship between sensor signals of welding variables and formation of keyhole and plasma is performed.

• Journal of the Korean Ceramic Society
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• v.41 no.2
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• pp.176-181
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• 2004

EAF (Electric Arc Furnace) dust is classified as special wastes containing heavy metal contaminants may cause to damage an environment such as underground water contamination if they were not treated properly. For reutilizing the EAF dust, the porous body was made from EAF dust/clay composition system, and analyzed pore characteristics. It was found that a light-aggregate body was made up two different microstructures. One was non-black and dense microstructure which located near surface, and the other was black and porous microstructure (black coring) which located inner part. For systematizing the relationship of the black-coring area and the bloating degree, we defined the Ic(core index) and Is(shell index). It was found that the optimal bloating conditions of artificial light-weight aggregate were more than 0.5 of Ic and 0.4 of Is.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.683-684
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• 2009

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.829-830
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• 2010

• Journal of the Ergonomics Society of Korea
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• v.33 no.6
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• pp.565-575
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• 2014

Objective: The aim of this study is to evaluate the effect of weight of load and time on the physical workload of repetitive upper-limb tasks with handling light weight loads using EMG and perceived discomfort, and to investigate the relationship between EMG and perceived discomfort for those repetitive tasks of moving light weight loads. Background: Repetitive upper-limb motion is known as one of the main risk factors of musculoskeletal disorders, and a lot of repetitive tasks are carried out while handling light weight loads in the industry. In evaluating the workload of repetitive tasks handling light weight loads, EMG and perceived discomfort can be used, though their relationship in those work conditions are not much investigated. Method: A laboratory experiment with 18 healthy males were conducted to record EMG signals from 5 muscle sites of the right arm and shoulder and rate perceived discomforts for the body parts and the whole body while carrying out repetitive materials-handling tasks for 52min. The subjects were divided into 3 groups which handled the loads of 1kg, 2kg and 3kg, respectively. ANOVAs were conducted to analyze the effects of the weight and time on RMS of EMG amplitude (normalized RMS: NRMS), median frequency of power spectrum of EMG (normalized MDF: NMDF) and perceived discomfort. The correlations between NRMS and NMDF and perceived discomfort were also analyzed. Results: Statistically significant muscular fatigue effects were not found from NRMS and NMDF in most muscles, while there were significant increases of discomfort as the task time elapsed. It was shown that there were an increasing trend of the muscular activity as the weight of load increased and a decreasing trend of median frequency of EMG of upper and lower arms as time elapsed. It was found that there were significant negative correlations between NMDFs from the lower arm and discomfort ratings, though the relationships were weak. Conclusion: It can be concluded that the working conditions adopted in this study were not enough to induce muscular fatigue, while there was significant increase in perceived discomfort. A further study is necessary to integrate the objective and subjective measures for more reliable and sensitive evaluation of workload of repetitive tasks of handling light weight loads. Application: This study can be used as a basic study for the evaluation of workload of repetitive tasks handling light weight loads.

• Journal of the Korean Society of Clothing and Textiles
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• v.23 no.1
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• pp.159-169
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• 1999

The purpose of this study was to study real body size and ideal body shape by considering the relations of between the degree of satisfaction and consciousness of body cathexis and real body size and to understand change of the degree of satisfaction at body part and ideal body shape with the changes of the times by comparing the date taken at 1997 to that taken at 1992. The subjects in this study were 542 and 201 female college students aged from 18 to 25 Body. measurements and survery were taken from April to June 1997, and May to June 1992 Data were analyzed by correlation analysis ANOVA duncan test and crosstabulation analysis The results were as follows : (1) The subjects tended to be satisfied with long and slim limbs silm trunk and preferred to be tall in height and light in weight. But exceptionally they tended to be unstatisfied with small bust as well as big one. (2) The subjects want to be slimmer lower body than upper body. (3) The subjects of 1997 was more statisfied with tall height light weight slim limbs and narrow shoulder than those of 1992. (4) The ideal body shape of the subject of 1997 was slim body while that of the subject of 1992 was big bust and wasp waist. (5) The subject of 1997 was more satisfied with leanner body than that of 1992.

• Development and Reproduction
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• v.20 no.1
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• pp.23-29
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• 2016

In fish, light (photoperiod, intensity and spectra) is main regulator in many physiological actions including growth. We investigate the effect of light spectra on the somatic growth and growth-related gene expression in the rearing tiger puffer. Fish was reared under different light spectra (blue, green and red) for 8 weeks. Fish body weight and total length were promoted when reared under green light condition than red light condition. Expression of somatostatins (ss1 and ss2) in brain were showed higher expression under red light condition than green light condition. The ss3 mRNA was observed only higher expression in blue light condition. Expression of growth hormone (gh) in pituitary was detected no different levels between experimental groups. However, the fish of green light condition group was showed more high weight gain and feed efficiency than other light condition groups. Our present results suggest that somatic growth of tiger puffer is induced under green light condition because of inhibiting ss mRNA expression in brain by effect of green wavelength.