• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1446-1448
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• 2002

The short-time permissible temperature of an overhead distribution line conductor is determined by the softening characteristics of ACSR-OC, ACSR AW/OC 160, typical conductors employed in the overhead distribution line. Transient heat transfer equation and Newton's cooling law were applied to analyze the heating and cooling effects of the insulating conductors, respectively, and the error of co-relation was calibrated after simulating the softening test to assess the short-time characteristic of the insulating conductor. In order to verify the softening characteristic, the conductors were tested with heat cycle. The test was totally carried out 200 cycles, and 1 cycle was to heat and cool at 1.1 times permissible current of the conductor, 1.15 times for 120 minutes, respectively. After heating, the tensile strength and surface of the conductor were observed. In case of ACSR-OC, as the result of 100 hour heating test, the tensile strength of the insulator was 0.8 times the initial value. This is equivalent to the value of the conductors which are used for 10 years at sites.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1130-1135
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• 2004

The vertical roller mill is the important machine grinding and mixing various crude materials in the manufacturing process of portland cement. Vertical roller mill is subjected to the cyclic bending stress by rollers load. It demands $4{\times}10^7$ cycle but has $4{\times}10^6{\sim}8{\times}10^6$ cycle. It fractures at the edge of grinding path of outside roller. The repair expense for it amounts to 30% of total maintenance. Therefore, this study shows optimal design for vertical roller mill using DOE and neural network.

• Journal of the Korean institute of surface engineering
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• v.23 no.4
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• pp.225-229
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• 1990

Solubility Products of metal oxides, such as Al2O3 and UO2 in KCl-LiCl eutectic composition was calculated by using an exact an exact thermodynamic. The values for Al2O3 ThO2 and UO2 were found to be 2.51$\times$10-27, 4.97$\times$10-15and 2.17$\times$10-12in mole per liter basis at 743 K, respectively. The correlation of theoretical values with those of experiment were in good agreement. It is worth to note that the exact cycle method was proved to be satisfactory in making predictions of solubillities and also solubility products of sparingly soluble metal oxides in an ionic salt system.

• The Korean Journal of Mycology
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• v.14 no.1
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• pp.9-15
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• 1986

Interspecific hybrids of Pleurotus ostreatus and Pleurotus florida were formed by using protoplasts of complementing auxotrophs. The genetic markers were shown to segregate and recombine in the first generation of monosporus isolates from basidiocarp of seven fusion products. The analysis provides proof of heterokaryosis and strong evidence for haploidy of vegetative nuclei, a sexual cycle consisting of nuclear fusion and meiosis. In all the crosses there was no evidence of linkage between the genetic markers. Clamp connections were formed in monosporus mycelia from basidiocarp of fusion products.

• Korean Journal of Animal Reproduction
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• v.24 no.1
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• pp.83-88
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• 2000

This study was conducted to determine the effect of repeated ultrasound-guided transvaginal retrieval of oocytes recovery, estrous cycle and ovarian adhesion in Korean native, Hanwoo heifers. Heifers were at unknown stages of the estrous cycle at the start of experiments in which all follicles $\geq$6mm in diameter were ablated. The results obtained in this study were as follows; Follicle developing number and oocytes collected number were no effected to repeated OPU to nine session, 4 e.a range oocytes collected to repeated OPU session. Oocytes were observated follicles were 8.7$\pm$4.2 e.a, collected oocytes were 4.1$\pm$3.4 e.a to two times collected per week and observated follicles was 10.2$\pm$6.1 e.a, collected oocytes were 4.3$\pm$2.9 e.a to one times collected per week, but no difference significantly(P＜0.05). Ovaries adhesive percentage to repeated OPU was eight ovaries adhisived(20%) of forty ovaries, three ovaries(7.5%) to 1~3 times oocytes collected, four ovaries(l0%) to 4~6 times, one ovaries(2.5%) to 7~9 times oocytes collected session. To repeated OPU effection, ovaries adhisive heifers were long estrous cycle(＞25 day) to 7 heads(87.5%) of 8 head, non-adhesive ovaries heifers were 5 heads(41.7%) were long estrous cycle to repeated OPU 12 heads. Although, now unknown about the dynamics of follicles wave and about functional changes to repeated OPU ovaries, more question about ovaries adhesive cause remain.

• Journal of the korean society of oceanography
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• v.32 no.3
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• pp.156-161
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• 1997

The biogeochemical cycle of silver has rarely been reviewed, even though the silver ion (Ag$^{\times}$) is extremly toxic to some organisms. Its concentration is still rising sharply because of increased anthropogenic activity, specifically the discharge from the film industry (mainly, silver thiosulfate: Ag (S$_2$O$_3$)${^3-}_2$). Recently, a number of researchers have quantified the major fluxes and reservoirs of silver in the open ocean, bays, and estuaries. A review of the available information for Ag cycling in the open ocean shows that the riverine input (from human activity and weathering processes: 7${\times}$10$^6$ kg/yr and 5${\times}$10$^6$ kg/yr, respectively) is the dominant source of Ag to estuarine and coastal regions. Most of the silver (90% of riverine input silver) is removed in coastal sediments by the physical-chemical character of silver due to its high partitioning with particulate matter. On the other hand, in the open ocean the atmospheric input (wet and dry deposition: 1.48${\times}$10$^6$ kg/yr and 1.94${\times}$ 10$^5$ kg/yr, respectively) becomes more important as a source of silver than riverine input. The residence time of silver calculated from available data is 1250 yrs in the deep ocean below 500 m, but only 3 yrs in the surface ocean.

• Journal of Korean Society of Transportation
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• v.18 no.2
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• pp.73-89
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• 2000

This Paper documents the development of a cycle free based, coordinated dynamic signal timing model for minimizing queue lengths using Genetic A1gorithm. The model was embodied using MAT-LAB, the language of technical computing. A special feature of this model is its ability to manage queue lengths of turning movements at the start of green times. The model produces a cycle-free based signal timing(cycles and green times) for each intersection to minimize queue lengths of turning movements on the cycle basis. Concurrently, appropriate offsets could be accomplished by applying cycle-free based signal timings for respective intersections. The model was applied to an example network which consists of three intersections. The result shows that the model produces superior signal timings to the existing signal timing model in terms of managing queue lengths of turning movements.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2289-2297
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• 1996

Flows in the combustion chamber near the spark plug are measured using LDv.A single cylinder DOHC S.I. engine of compression ratio 9.5:1 with a transparent quartz window piston is used. Combustion chamber shape is semi-wedge type. Measured data are analyzed using the ensemble averaged analysis and the cycle resolved analysis which uses FFT Filtering. Turbulent intensity and mean velocity are studied in the main flow direction and the normal to main flow direction as a function of engine speeds. The results shows that the turbulent intensity obtained by the ensemble averaged analysis is greater than that calculated by the cycle resolved analysis. Especially, the ensemble averaged analysis shows increase in turbulence at the end of compression stroke although the cycle resolved analysis shows increase only in the cycle-by-cycle variation with no noticeable increase in turbulence. The mean velocity in the main flow direction increase as engine speed increase. But the mean velocity normal to the main flow does not show such increase. Turbulent intensity in both direction increase in proportion to engine speeds. The magnitude of turbulent intensity is about 0.3 ~ 0.4 times the mean piston speeds at the end of the compression stroke.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.6-9
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• 2001

In this research, a experiment was performed to evaluate the electrical properties of outdoor insulator with the pollution cycle method. Cycle test methods such as DCM of STRI, IEC 61109 compared with pollution cycle method. Using dimatic properties of Korea peninsula, we could get the optimal condition for the pollution cycle method. As the factor, clean and saline fog, voltage, rainfall and drying was chosen. The applied voltage is 13,2 kV, the salinity of salt solution was changed from 0.1 wt% to 1.5 wt% and one cycle is about 4 hours. To ensure the reproducibility and reliability, experiments repeated 4 times. The leakage current was measured with Lab VIEW and the ESDD was measured with brushwiping method. This experiment could ensure superiority of pollution cycle method which developed through the result of this experiment and we could know the relationship between ESDD, leakage current and relative humidity.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.7
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• pp.704-711
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• 2005

In this study, life cycle assessment(LCA) for the nuclear power generation system and the thermal power generation system, which make a great distribution of the electric power supply in Korea, has been carried out to compare the environmental impact between two power generation systems. In system boundary of this study, the stage of construction, operation and demolition & disposal were included. For life cycle impact assessment(LCIA), three cases were considered; the single environmental impact for the $CO_2$ emissions, the 8 major global environmental impact, and the major global environmental impact categories including radioactive impact. As the results, it was found that the nuclear power generation system is environmentally superior to the thermal power generation system as 10,000 times in the evaluation for the $CO_2$ emissions, 90 times in the evaluation for the 8 major environmental impact categories, and 40 times in the evaluation for the environmental impact categories including radioactive impact.