• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.324-330
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• 1999

$Si_3N_4$-$TiB_2$ with 2 wt% $Al_2O_3$ and 4 wt% $Y_2O_3$ additives was hot pressed in a flowing $N_2$ environment with varying $TiB_2$ content from 10 to 50 vol%. Variations of mechanical (hardness, fracture toughness, and flexual strength), and tribological properties as a function of $TiB_2$ content were investigated. As the content of $TiB_2$ increased, relative density decreased due to the chemical reaction of $TiB_2$in $N_2$ environment. The reduction of density causes mechanical properties to be degraded with an increase of $TiB_2$ in $Si_3N_4$. Tribological properties were dependent of microstructure as well as mechanical properties, however, they were degraded strongly by the chemical reaction of $Si_3N_4$-$TiB_2$ during hot pressing in $N_2$ environment. SEM and TEM observations, and X-ray diffraction analysis that the chemical reaction products at the interface are TiCN, Si, and $SiO_2$. Also, the comparison of XRD patterns of the $Si_3N_4$-40 vol% $TiB_2$ composites hot pressed at $1,750^{\circ}C$ for 1 hour between in $N_2$ and in Ar gas was made. The XRD peaks of Si and $SiO_2$ were not found in Ar, but still a weak peak of TiCN was presented.

• Animal Bioscience
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• v.37 no.6
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• pp.1130-1139
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• 2024

Objective: The daily maximum temperature and seawater level continuously increase as global warming continues. We examined the adaptability and production performance of heat-stressed goats with a supply of low-saline drinking water. Methods: Twelve Kacang and Kacang Etawah cross goats were exposed to two climatic conditions (control, 25℃ to 33℃, 83% relative humidity [RH], temperature humidity index [THI]: 76 to 86; and hot environment, 26℃ to 39℃, 81% RH, THI: 77 to 94) and two salt levels in drinking water (0% and 0.4% NaCl). The experimental design was a Latin Square (4×4) with four treatments and four periods (28 days each). Results: Temperature of the rectal, skin, and udder, and respiration rate rose, reached a maximum level on the first day of heat exposures, and then recovered. Plasma sodium rose at 0.4% NaCl level, while the hot environment and salinity treatments increased the drinking water to dry matter (DM) intake ratio. Water excretion was elevated in the hot environment but lowered by the increase in salinity. Total lying time increased, whereas change position frequency decreased in the hot condition. Lying and ruminating and total ruminating time increased and explained the enhanced DM digestibility in the hot conditions. Conclusion: The goats exhibited a high level of plasma sodium as salinity increased, and they demonstrated physiological and behavioral alterations while maintaining their production performances under increasing daily maximum temperatures.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.91-94
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• 2003

A field pilot-scale demonstration of an enhanced SVE using hot air injection and extraction was conducted to remove diesel range compounds from subsurface soils at a site in J-city, Korea. The objective of demonstration was to evaluate field ISR by intrinsic microorganism after an application study of hot air-SVE technology and to calculate each first-order kinetic with soil temperature. TPH concentration of contaminated soil at the site was approximately 2, 000~11, 000 mg/kg (average 6, 900 mg/kg) with depths greater than 5 m bgs. The 1st-order reaction rate constants, k were 0.0438(@about5$0^{\circ}C$), 0.0564(@4$0^{\circ}C$), and 0.0685(@33$^{\circ}C$) d-1 respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.63-67
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• 2004

A field pilot study on remediation of diesel-contaminated soil by hot air injection/extraction process constructing soil piling system was conducted to evaluate the effects of hot air on the removal of diesel and each constituent. After the heating process of 2 months, the equilibrium temperature of soil reached to 10$0^{\circ}C$ and soil TPH concentration was reduced to about 72% against the initial concentration. Additional extraction process of 2 months induced the continuous extraction of residual diesel and the increment of microbial activity, which made soil TPH concentration reduced to 95%. In addition biological removal of non volatile constituents in diesel was verified indirectly and the removal pattern of each DRO(diesel range organic) as soil temperature was explained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.772-775
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• 2002

The remote handling and maintenance devices in the nuclear hot ceil should be checked prior to the hot operation in view of reliability and operability. In this study, the digital mock-up is implemented to analyze and define the process equipment maintenance processes instead of real mock-up, which is very expensive and time consuming. To do this, the parts of equipment and maintenance devices are modeled in 3-D graphics, assembled, and kinematics is assigned. Also, the virtual workcell of the spent fuel management process is implemented in the graphical environment which is the same as the real environment. This simulator has the several functions for verification such as analyses for the manipulator's working area, the collision detection, the path planning and graphic simulation of the processes etc. This graphic simulator of the maintenance devices can be effectively used in designing of the maintenance processes for the hot cell equipment and enhance the reliability of the spent fuel management.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1354-1358
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• 2003

The process equipment for handling high level radioactive materials like spent fuels is operated in a hot cell, due to high radioactivity. Thus, this equipment should be maintained and repaired optimally by a remotely operated manipulator. The master-slave manipulators(MSM) are widely used as a remote handling device in the hot cell. The equipment in the hot cell should be optimally placed within the workspace of the wall-mounted slave manipulator for the maintenance operation. But, because of the complexity in the hot cell, there would be some parts of the equipment that are not reached by the MSM. In this study, the maintenance process for these parts of the equipment is developed using virtual prototyping technology. To analyze the workspace of the maintenance device in the hot cell and to develop the maintenance processes for the process equipment, the virtual mock-up of the hot cell for the spent fuel handling process is implemented using IGRIP. For the implementation of the virtual mock-up, the parts of the equipment and maintenance devices such as the MSM and servo manipulator are modeled and assembled in 3-D graphics, and the appropriate kinematics are assigned. Also, the virtual workcell of the spent fuel management process is implemented in the graphical environment, which is the same as the real environment. Using this mock-up, the workspace of the manipulators in the hot cell and the operator's view through the wall-mounted lead glass are analyzed. Also, for the dedicated maintenance operation, the analyses for the detailed area of the end effectors in accordance with the slave manipulator's position and orientation are carried out. The parts of the equipment that are located outside of the MSM's workspace are specified and the maintenance process of the parts using the servo manipulator that is mounted in the hot cell is proposed. To monitor the process in the hot cell remotely, the virtual display system by a virtual camera in the virtual work cell is also proposed. And the graphic simulation using a virtual mock-up is performed to verify the proposed maintenance process. The maintenance process proposed in this study can be effectively used in the real hot cell operation and the implemented virtual mock-up can be used for analyzing the various hot cell operations and enhancing the reliability and safety of the spent fuel management.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1075-1075
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• 2006

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.88-93
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• 2005

In this study, the operational characteristics on heating performance and energy consumption for intermittent hot water heating system in apartment buildings were research by simulation. The effects of apartment inlet hot water temperature and operation time per day on energy consumption and indoor thermal environment are investigated. The strategy of energy saving and thermal environment improvement is suggested in comparison with the existing ones.

• Journal of Korean Society on Water Environment
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• v.27 no.3
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• pp.357-363
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• 2011

In spite of numerous advantages in railroads such as mass transportation, high reliability, and environmental soundness etc., the value of railroad construction is relatively underestimated compared to road. This is because the current method of evaluation focuses mainly on economic effect. In this study, considering recent research results, the environmental value of railroad construction was assessed by calculating the effect of reduction of emissions and water contamination. With these two benefits, the environmental effect produced by railroads and road construction was calculated and compared to each other using EMME/3. As a result, the senario 4 which considers 'Hot/Cold start' condition and water contamination had highest benefits. Furthermore, the environmental effect produced by railroad is 55~101% higher than road construction. If the suggested method is used in the current appraisal system, the environment-friendly mode like railway would be highly valued, much more than before.

• Korean Journal of Environment and Ecology
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• v.35 no.6
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• pp.659-668
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• 2021

The purpose of this study is to propose a ventilation corridor management plan to improve the thermal environment for Busan Metropolitan City. To this end, the characteristics of hot and cool spots in Busan were identified by conducting spatial statistical analysis, and thermal image data from Landsat-7 satellites and major ventilation corridors were analyzed through WRF meteorological simulation. The results showed the areas requiring thermal environment improvement among hot spot areas were Busanjin-gu, Dongnae-gu, industrial areas in Yeonje-gu and Sasang-gu, and Busan Port piers in large-scale facilities. The main ventilation corridor was identified as Geumjeongsan Mountain-Baekyangsan Mountain-Gudeoksan Mountain Valley. Based on the results, the ventilation corridor management strategy is suggested as follows. Industrial facilities and the Busan Port area are factors that increase the air temperature and worsen the thermal environment of the surrounding area. Therefore, urban and architectural plans are required to reduce the facility's temperature and consider the ventilation corridor. Areas requiring ventilation corridor management were Mandeok-dong and Sajik-dong, and they should be managed to prevent further damage to the forests. Since large-scale, high-rise apartment complexes in areas adjacent to forests interfere with the flow of cold and fresh air generated by forests, the construction of high-rise apartment complexes near Geumjeongsan Mountain with the new redevelopment of Type 3 general residential area should be avoided. It is expected that the results of this study can be used as basic data for urban planning and environmental planning in response to climate change in Busan Metropolitan City.