• Korean Journal of Ichthyology
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• v.22 no.1
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• pp.25-33
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• 2010

Effects of different salinity levels on spawning performance, embryonic development and early viability of a euryhaline medaka species, Oryzias dancena, were examined. O. dancena were able to spawn eggs in a wide range of salinity from 0 to 70$^{\circ}/_{\circ\circ}$, however, the spawning frequency was lowered in complete freshwater (0$^{\circ}/_{\circ\circ}$) and in highly salted water (70$^{\circ}/_{\circ\circ}$). Fertilization success was negatively affected when the environmental salinity was higher than the salt concentration found in normal seawater. Embryonic viability and hatching success were also inversely related with the salinity levels. Typical abnormality was observed in developing embryos incubated at high salinities (30, 45 and 60$^{\circ}/_{\circ\circ}$). In addition, the time to hatch was significantly delayed with increasing salinities: peak hatching occurred at 12~14 days post fertilization (dpf) in freshwater and at least at 17 to 18 dpf in 60$^{\circ}/_{\circ\circ}$. Mean survival rates of the hatched larvae up to 7 days post hatching (dph) were at least 97% in salinity levels ranging from 0 to 30$^{\circ}/_{\circ\circ}$. However, larvae reared in 45 and 60$^{\circ}/_{\circ\circ}$ experienced significant mortality, especially in the early phase, resulting in only 75% and 64% survival rates up to 7 dph, respectively.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.1-10
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• 2011

Unfortunately, in current microprocessors, increasing the frequency causes increased power consumption and reduced reliability whereas it improves the performance. To overcome the power and thermal problems in the singlecore processors, multicore processors has been widely used. For 2D multicore processors, interconnection is regarded as one of the major constraints in performance and power efficiency. To reduce the performance degradation and the power consumption in 2D multicore processors, 3D integrated design technique has been studied by many researchers. Compared to 2D multicore processors, 3D multicore processors get the benefits of performance improvement and reduced power consumption by reducing the wire length significantly. However, 3D multicore processors have serious thermal problems due to high power density, resulting in reliability degradation. Detailed thermal analysis for multicore processors can be useful in designing thermal-aware processors. In this paper, we analyze the impact of workload distribution, distance to the heat sink, and number of stacked dies on the processor temperature. We also analyze the effects of the temperature on overall system performance. Especially, this paper presents the guideline for thermal-aware multicore processor design by analyzing the thermal problems in 2D multicore processors and 3D multicore processors.

• Journal of the Korean Magnetics Society
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• v.8 no.1
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• pp.13-20
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• 1998

The crystallographic and high frequency characteristics of $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ soft magnetic alloys were investigated under the magnetic field annealing. As-cast ribbon with which already imbedded nanocrystalline Fe-Si phase on the surface have a preferred orientation with (400) plane to surface and also with the [011] direction parallel to the ribbon length. The extra nanocrystalline Fe-Si phase appeared throughout at 45$0^{\circ}C$ in samples with or without the longitudinal magnetic field. However the formation of nanocrystalline phase does not appear on the suface layer until 50$0^{\circ}C$ annealing temperature under the transverse field. The cryststallization fraction of annealed samples with longitudinal magnetic field is higher than that of samples without magnetic field. When the transverse magnetic field is applied, the crystallization fraction does not increases but decreases until 50$0^{\circ}C$. However the crystallization of internal regions can be confirmed by X-ray diffraction measurement via tilting the sample. It was found that for all samples, the saturation induction were all same with 1.3 T. The coercive field of as-cast sample was 1.06 A/cm, but in annealed samples it decrease from 0.56 to 0.1 A/cm with increasing annealing temperature from 400 and 55$0^{\circ}C$, respectively. The squareness of annealed samples under transverse magnetic field has a small value than that of both without field and with longitudinal field annealing.

• Journal of the Korean Society of Radiology
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• v.11 no.7
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• pp.663-669
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• 2017

In diagnostic medical imaging, it is essential to reduce the scattered radiation for the high medical image quality and low patient dose. Therefore, in this study, the influence of the scattered radiation on medical images was analyzed as the tube voltage increases. For this purpose, ANSI chest phantom was used to measure the scattering ratio, and the scattering effect on the image quality was investigated by RMS evaluation, RSD and NPS analysis. It was found that the scattering ratio with increasing x-ray tube voltage gradually increased to 48.8% at 73 kV tube voltage and to 80.1% at 93 kV tube voltage. As a result of RMS analysis for evaluating the image quality, RMS value according to increase of tube voltage was increased, resulting in low image quality. Also, the NPS value at 2.5 lp/mm spatial frequency was increased by 20% when the tube voltage was increased by 93 kV compared to the tube voltage of 73 kV. From this study, it can be seen that the scattering radiation have a significant effect on the image quality according to the increase of x-ray tube voltage. The results of this study can be used as basic data for the improvement of medical imaging quality.

• Journal of Preventive Medicine and Public Health
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• v.10 no.1
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• pp.80-85
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• 1977

The Korean family planning program began in 1962, originating both in a concern for family well-being and in a concern over a high population growth rate which was cancelling advances in economic capacity. The new program was frank and vigorous in its advocacy of birth control. In recent years, voluntary sterilization as a family planning method has many attributes that cause users of contraceptives to regard it as an ideal method in Korea. A point of these view, author performed a follow-up study on effects of vasectomy and tubal ligation on sociomedical aspects of total 136 men sterilized and 96 women sterilized in Sunsan Gun, Kyungpook Province as of July, 1977. The results were summerized as follows: An average age of vasectomized men was 37.0 and that of tubal ligated women, 34.9. The average duration of marital life was 13.9 years in men sterilized and 14.6 years in women sterilized. An average number of living children at the time of sterilization was 3.6 in men sterilized and that of living children, 3.7 in women sterilized. The most predominant reason for the sterilization was birth control in both (91% in men, 52% in women) and the most common motivating socilitator was family planning field workers (71% in men, 48% in women). About 51 percent of men sterilized and 50 percent of women sterilized were used contraceptive methods before the operation. Experience of induced abortion is reported in 65 percent of wives of men sterilized and 64 percent of women sterilized. In sexual feeling after sterilization, respondents shelved increasing coital frequency 21 percent in men sterilized and 10 percent in women sterilized. Sixty-five percent in men sterilized and 64 percent in women sterilized would recommend the operation to others.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.363-375
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• 1997

This study encompasses the performance of static and fatigue test for the 8 large scale test specimens to clarify the fatigue behavior of coped stringer and the effect of the repair and strengthening on the damaged stringer of the floor system in steel railway bridges. For the purpose of the research, the actual stress wave for the existing bridge was measured, the basic stress range frequency histogram was made and the equivalent stress range was calculated. Using the result from the equivalent stress range made by adjusting the stress range, the static and fatigue test was carried out by identifying the previous rehabilitation and after. As the result of the static tests, it was revealed that the level of local stress under the S1 specimen test of the real equivalent stress range was similar to tensile strength of the test material, and it was consistent with the requirement of the initiation condition of the fatigue crack. Through the various rehabilitation methods to the damaged specimens, the effects of the repair and reinforcement were analyzed. According to the results of the repair of effect, bolting the high tension bolt over the stop hole was confirmed to be more adequate method than drilling only stop hole to delay the fatigue crack growth. Futhermore, in case of the stringer subjected by bending moment, the reinforcement over the upper flange side was determined to be a useful strengthening method, and the reinforcement to the web of the stringer was not appropriate to accomodate as a adequate strengthening method. Also it was confirmed that the category of the fatigue design for the coped stringer met with the category E specified on the fatigue design criteria of the Highway Standard Specification in Korea.

• 대한공업교육학회지
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• v.42 no.1
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• pp.140-159
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• 2017

The purpose of this research was to collect and select the theses and articles of the STEAM education in domestic and to analyze a research status by the review, then to suggest a direction of the further research in technology education. The objects of this research were the theses and articles of the STEAM education in domestic published from January 2007 to June 2016. I collected the theses and articles by using the search engine of the Korean Academic Information Service, the Korea Education and Research Information Service, the National Assembly Digital Library, and finally selected 821 theses and articles for the objects. I analyzed the theses and articles by verifying their subjects, abstracts and contents, and applied the analysis framework developed in advance. I used the frequency analysis, the cross analysis to analyze the datas statistically. Also, I used SPSS 18.0 program. Drawing on the finding of this research, major conclusions of this research were as follows. First, the researches of the STEAM education in domestic had been studied numerously from 2012 to 2015, but it has been decreased since 2016. Second, the researches of the STEAM education in domestic have been studied numerously for the development of the educational program and the instructional source. Third, the research objects of the STEAM education in domestic have been studied numerously for elementary school, middle school and high school in a row. Forth, the researches of the STEAM education in domestic have been focused numerously on a science. Fifth, the researches of the STEAM education in domestic have been concerned mainly about the creativity effect among other educational effects.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.2
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• pp.71-81
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• 1987

Nowadays, the high development of industrial technique demands the optimal design of marine structures to be welded under the water, because the underwater welding of the ship hull and marine structures can decrease manpower and cost of production. However there is not available at present any report on fatigue behavior about underwater welded joints. In this paper under tention- tension repeated fatigue stress with frequency of 10 cycles per second by local controlled system, the fatigue strength properties of underwater welded joints of SM41A-2 Plate-to-Plate of 10 mm thickness were experimentally examined. The results obtained were as follows : 1) The fatigue strength of underwater welded joints of SM41A-2 was peaked at the heat input of about 1, 400 joule/mm(180 A, 36 V), while, at the heat input of more than about 1, 100 joule/mm (160 A, 33 V) that of the underwater welds at the higher than cycle of life rather than the lower cycle was higher than that of the base metal but lower than that of the atmosphere welds on account of both cooling and notch effects. 2) The fatigue limit of underwater welds increased with an increase of heat input resulting in a peak of that at the heat input of about 1, 400 joule/mm and then decreased gradually. 3) The fatigue strength at N cycles was peaked between the heat input of about 1, 400 and 1, 700 joule/mm where the strain was rapidly increased. 4) It was confirmed that the optimal zone of heat input condition for obtaining the underwater welds fatigue strength higher than that of the base metal exists, and if out of this zone, the fatigue strength of the underwater welds was lower than that of the base metal because of lack weld penetration, inclusion of slag, voids, etc. 5) By the fatigue test, the underwater welds fractured brittly without visual deformation, so the strain was remarkably less than of the atmosphere welds. 6) The fatigue life factor was peaked at the heat input of about 1, 600 joule/mm (200 A, 36 V) at which the mean strain is a little higher than that of the base metal but quite lower than those of the atmosphere welds, resulting in good underwater welds because both fatigue strength and ductility of the underwater welds are higher than those of the base metal at such heat input.

• Women's Health Nursing
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• v.3 no.2
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• pp.129-156
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• 1997

The purpose of this study is to investigate the relationship between depression and ego identity of middle-aged women and to identify the variables that show differences in the depression and ego identity of middle-aged women. The subjects in the study were 321 mothers of high school students whose age were 40-59 years old. The instruments for this study were Beck Depression Inventory(BDI) developed Beck(1978) and translated by Lee(1981) and Ego identity Scale developed Suh(1975) and modified by Nam(1975). The reliability values of BDI range from 0.83 to 0.87 and Ego identity range from 0.81 to 0.85 using Cronbach alpha. The data were analysed by using the SAS program and included Frequency, percentage Pearson Correlation MANOVA, t-test, ANOVA. The conclusion obtained from this study were as follows ; 1) There was a negative correlation(r=-0.21, p=0.0002) between depression and ego identity of middle-aged women. Thus the lower depression the higher ego identity for middle-aged women. 2) According to the analysis of interacting effects of depression and ego identity, there were significant differences in the household income(F=0.38, p=0.0035), level of education (F=6.50, p=0.0001), satisfaction of marriage(F=10.45, p=0.0001), family pattern (F=6.18, p=0.0001), menopausal status(F=7.23, p=0.0001), present disease(F=4.85, p=0.0110) and health status(F=9.00, p=0.0001). 3) There were significant differences on the level of education(F=12.98, p=0.0001) household income(F=5.78, p=0.0007), support of spouse(F=8.58, p=0.0002), satisfaction of marriage(F=20.08, p=0.0001), menopausal status(F=11.32, p=0.0001), present disease(t=2.76, p=0.0062) and health status(F=17.23, p=0.0001) of the depression of middle-aged women. 4) There were significant differences on the patterns of household(t=-2.64, p=0.0086), support spouse(F=3.58, p=0.0291), satisfaction of marriage(F=3.90, p=0.0212), menopausal status(F=4.59, p=0.0108) and disease(t=2.11, p=0.0359) of the ego identity of middle-aged women. On the basis of the above findings the following recommendations are made ; 1) According to results of this study, middle-aged women's depression is correlated with ego identity. Thus when the nurse plans the preventive strategy of middle-aged women's depression, the nurse must be considered with level of ego identity. 2) To study for middle-aged women in depth, further research is need to study regard to middle-aged men and their children.

• Journal of Korean Neurosurgical Society
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• v.52 no.6
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• pp.509-512
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• 2012

Objective : The purpose of this study is to evaluate neuroprotective effect of sacral neuromodulation in rat spinal cord injury (SCI) model in the histological and functional aspects. Methods : Twenty-one female Sprague Dawley rats were randomly divided into 3 groups : the normal control group (CTL, n=7), the SCI with sham stimulation group (SCI, n=7), and the SCI with electrical stimulation (SCI+ES, n=7). Spinal cord was injured by dropping an impactor from 25 mm height. Sacral nerve electrical stimulation was performed by the following protocol : pulse duration, 0.1 ms; frequency, 20 Hz; stimulation time, 30 minutes; and stimulation duration, 4 weeks. Both locomotor function and histological examination were evaluated as scheduled. Results : The number of anterior horn cell was $12.3{\pm}5.7$ cells/high power field (HPF) in the CTL group, $7.8{\pm}4.9$ cells/HPF in the SCI group, and $6.9{\pm}5.5$ cells/HPF in the SCI+ES group, respectively. Both the SCI and the SCI+ES groups showed severe loss of anterior horn cells and myelin fibers compared with the CTL group. Cavitation and demyelinization of the nerve fibers has no significant difference between the SCI group and the SCI+ES group. Cavitation of dorsal column was more evident in only two rats of SCI group than the SCI+ES group. The locomotor function of all rats improved over time but there was no significant difference at any point in time between the SCI and the SCI+ES group. Conclusion : In a rat thoracic spinal cord contusion model, we observed that sacral neuromodulation did not prevent SCI-induced myelin loss and apoptosis.