• Journal of Urban Science
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• v.7 no.1
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• pp.5-9
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• 2018

The nickel-titanium shape memory alloy (SMA), referred to as Nitinol, exhibits a superelastic effect that can be restored to its original shape even if a significant amount of deformation is applied at room temperature, without any additional heat treatment after removal of the load. Owing to these unique material characteristics, it has widely used as displacement control devices for seismic retrofitting in civil engineering fields as well as medical, electrical, electronic and mechanical fields. Contrary to ordinarty carbon steel, superelastic SMAs are very resistant to fatigue, and have force-displacement properties depending on loading speed. The change for the mechanical properties of superelastic SMAs are experimentally inviestigated in this study when loading cycle numbers and loading speeds are different. In addition, the standardized force-displacement properties of such superelastic SMAs are proposed with an aim to efficiently design the seismic retrofitting devices made of these materials.

• Journal of Urban Science
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• v.7 no.1
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• pp.1-4
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• 2018

Due to the strong relationship between Baekje, one of the ancient Korean Kingdom and Japan through the same religion, Buddhism, it is possible to find many similarities in remains, such as temples, and pagodas, and in many relics, in both cities. However, from the point view of urban planning, Buyeo, originally designed as the fortress city, has a different city planning strategies from that of Kyoto which is a straight-lined city. After Buyeo was destroyed by Silla, one of the Three Kingdoms in Korea, it got deemphasized in Korean history. Later, Buyeo's recent city planning was directly affected and implanted in Japanese Imperialism period (1910-1945) one which emphasizes the layout of Japanese temple which serves as the center of the ceremonies for their ancestors. Thus, it is possible to find cultural interrelation in urban planning between two cities throughout the history of Korea and Japan.

• Journal of Urban Science
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• v.7 no.1
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• pp.45-54
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• 2018

The purpose of this study is to find the factors that reduce prediction error in traffic volume using highway traffic volume data. The ARIMA model was used to predict the day, and it was confirmed that weekday and weekly characteristics were distinguished by prediction error. The forecasting results showed that weekday characteristics were prominent on Tuesdays, Wednesdays, and Thursdays, and forecast errors including MAPE and MAE on Sunday were about 15% points and about 10 points higher than weekday characteristics. Also, on Friday, the forecast error was high on weekdays, similar to Sunday's forecast error, unlike Tuesday, Wednesday, and Thursday, which had weekday characteristics. Therefore, when forecasting the time series belonging to Friday, it should be regarded as a weekly characteristic having characteristics similar to weekend rather than considering as weekday.

• Journal of Urban Science
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• v.7 no.1
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• pp.23-27
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• 2018

This research was carried out to investigate the corrosion prevention effect in the water distribution system by galvanized zinc-brass pipe which is using potential between brass and zinc. As a result of this study, pH and conductivity of influent were constant in spite of its installation, and it was difficult to estimate the effect of the installation with temporary increased and reduced concentration of Zn and Fe ions, respectively. However, since the corrosion rate of the steel coupon with galvanized zinc-brass pipe was relatively low, it has an effect of inhibiting corrosion.

• Journal of Urban Science
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• v.7 no.1
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• pp.39-43
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• 2018

This study investigates microstructural characteristics of alkali-activated cements incorporating slag and fly ash. Samples were prepared with four fly ash:slag ratios, i.e., 100:0, 90:10, 70:30 and 50:50, and they were synthesized by using an alkali activator. Microstructural characteristics of the alkali-activated cements were determined by XRD, TGA, SEM, N2 gas adsorption/desorption methods, and compressive strength test. The results showed that properties of alkali-activated fly ash/slag were significantly affected by slag contents. Alkali-activated fly ash/slag with slag content of 30-50% showed higher compressive strength than ordinary Portland cement paste. An increase in slag content resulted in a denser microstructure, which composed of amorphous gel, therefore contributed to strength development of the material.

• Journal of Urban Science
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• v.7 no.1
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• pp.55-61
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• 2018

Long bridges, such as suspension bridges and diagonal bridges, are complex phenomena that show different behaviors depending on the shape and rigidity of the cross sections, such as wind vibrations and liquid vibrations from earthquakes in liquid storage containers. This is called the lower skirt on the lower side of the bridge, and the installation of lower skirt is effective for release and vortex vibrations caused by rapid winds, and that increases the stability of the wind resistance of the bridge. Optimal shape and installation of the lower skirt is also essential to make maximum wind speed effect of the lower skirt. Therefore, this study proposes a numerical analysis method to control the vibration of a bridge by calculating the optimal installation angle of an optimal lower skirt according to the optimal control theory and this study evaluates the impact on the optimal control system by minimizing the dominance equation with an evaluation function,which is an indicator for evaluating the optimal control theory state.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.237-237
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• 2005

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.240-240
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• 2005

• Journal of Urban Science
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• v.9 no.1
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• pp.51-59
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• 2020

With the rapid development of China's industrialization and urbanization, air pollution has become a growing concern. The emergence of air pollution not only affects people's health, but also restricts the development of China's social economy. This paper puts forward specific measures for air pollution control by examining the causes of air pollution and by comparing air pollution status and management policies between Korea and China. Methods of control involve improving the urban environmental management mechanism, spreading awareness of urban environmental management and air pollution management laws and regulations system, strengthening clean energy utilization and urban environmental greening, increasing investment and management funds and more. Through these measures, urban environmental management in China can be accelerated and level of environmental management improved.

• Journal of Urban Science
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• v.9 no.1
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• pp.69-73
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• 2020

Sudokwon landfill("Sudokwon" means regions of Seoul, Kyunggi and Incheon metropolitan cities in Korea), the world's largest sanitary landfill, has been systematically managing statistics on the incoming and dumping wastes and satisfactorily controlling pollutants including leachate and LFG. According to our long time experience of LFG field monitoring, the emission of GHG from landfill estimated by the IPCC Guideline showed much difference with our results. C&D waste has high concentration of sulfate compared to other wastes. Increased C&D waste of dumping waste had changed the COD/sulfate ratio in the landfill, which caused the increase of H₂S gas and the decrease of CH₄ gas. But the IPCC estimation method does not consider the effects of sulfate. In addition to that, the oxidation factor of the cover soil is set to the default values of 0.1 but the measured values by the field monitoring, are showing much higher than that, especially in the closed landfill.