Wyniki wyszukiwania - Biblioteka Nauki

1

Statistical analysis of welding industry of South Korea

100%

Kim C. , Kang M. , Bae S.

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tom Vol. 36, nr 2

207-211

EN

Purpose: This paper represents the current status of welding industry of South Korea - how much the welding industry accounts for in monetary terms in the manufacturing industry of South Korea. Design/methodology/approach: We classify welding industry into welding equipment industry and materials & the welding engineering sub-industry. To decide the portion of the welding industry in other engineering industry, we adopt the Welding-Related Expenditures, Investments, and Productivity Measurement in U.S. Manufacturing, Construction, and Mining Industries, a report published by AWS in 2002. The statistical analysis was performed based on the NSO and KITA data. Findings: In South Korea, the welding-related portion in the engineering industry showed much higher figures - about 9 times higher in production amount and over 5 times in export amount - than the welding equipment and materials industry. In addition, the total production of the welding industry amounted to 2.6 billion $, indicating that the welding industry holds a very important place in the entire domestic industries. Research limitations/implications: The welding industry of South Korea was statistically analyzed using the welding related expenditure of the manufacturing industries. Research limitations/implications: This research quantitatively showed the relative importance of the welding industry in South Korea. Originality/value: Due to the nature of welding industry, it is difficult to identify the boundary of welding industry. In addition, monetary impact of welding industry was not revealed in practical manner. In this paper, we categorize the welding industry into two sub-industries and analyze the statistical data with our framework to reveal monetary impact of welding industry. With our results, it is possible to estimate the economical effects of welding industry in South Korea.

2

Inverter DC resistance spot welding of magnesium alloy AZ31

100%

Hwang I. , Kim D. , Kang M.

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2011

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tom Vol. 48, nr 2

112-117

EN

The welding lobes of AC resistance spot welding and inverter DC resistance spot welding for the magnesium alloy sheet AZ31 were compared and analyzed.

3

Weldability of 440 MPa galvanized steel with inverter DC resistance spot welding process

100%

Hwang I. , Yoon H. , Kang M. , Kim D.

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tom Vol. 42, nr 1

37-44

EN

Purpose: This paper comparatively analyzes resistance spot weldability depending on whether or not 440 MPa-grade steel is galvanized at inverter DC spot welding. Design/methodology/approach: To compare the resistance spot weldability depending on whether or not the steel is galvanized, an inverter DC welding system was designed. Then, using this system, both tensile strength testing and macro-section testing were conducted on SPRC440 (uncoated steel) and SGARC440 (galvanized steel), and weldability was evaluated. Suitable welding conditions were calculated using the resistance spot welding variables such as electrode force, welding time and lobe diagram on the welding current. The low limit of the lobe diagram was set to the low limit of the tensile strength of 440 MPa-grade steel while the high limit was set depending on whether or not expulsion was detected. Findings: Compared to uncoated steel, galvanized steel had lower suitable welding current conditions and a narrower lobe diagram. Research limitations/implications: This paper compared resistance spot weldability and lobe diagram depending on whether or not 440 MPa-grade steel is galvanized. Practical implications: This paper confirms the weldability of galvanized steel by comparing resistance spot weldability depending on whether or not steel is galvanized. Originality/value: For analysis of resistance spot weldability depending on whether or not steel is galvanized, weldability was compared between SPRC440 (uncoated steel) and SGARC440 (galvanized steel) under the same welding conditions. As a result, compared to uncoated steel, galvanized steel had lower suitable welding current conditions and a narrower lobe diagram.

4

Climatic Response of Tracheid Features of Picea meyeri Along Altitude Gradient of Luyashan Mountains of North China

75%

Wang M. , Jiang Y. , Zhang W. , Dong M. , Kang M. , Xu H.

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tom Vol. 65, nr 4

345--358

EN

Changing localized environmental conditions along altitude gradients could modify the responses of tree xylem structures to climate variations. To explore how trees adapt to local environment and respond to climate variants, we analysed the variation of Picea meyeri xylem tracheid features and the relationships with climate variables along an altitude gradient (1970, 2240, 2490 and 2650 m above sea level) of the Luyashan Mountains in the North China. The results mainly indicated the following: (1) tracheid number and diameter of P. meyeri showed significant differences among the four sites along the altitude gradient; (2) trees at site 2 (2240 m) and site 3 (2490 m) are similar in age, but the xylem tracheid number and diameter of these trees were significantly different, which may indicate different functional adaptation; (3) the relationships between xylem features' residual chronologies and the monthly climate data were inconsistent along altitude gradients, which indicated that the limiting factor of P. meyeri growth along the altitude gradients, shifted from drought stress at lower altitudes to low-temperature stress at higher altitudes.