• Bulletin of the Korean Mathematical Society
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• v.45 no.2
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• pp.269-271
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• 2008

We prove that a full jack field does not exist on the sum of a trivial bundle and the canonical bundle on $G_{2,4}$, the Grassmanian of 2-planes in 4-space.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.87-92
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• 2003

Generally, in jack up rig design for harsh environment, its leg height is a major factor for achieving a sufficient serviceability & operability in terms of the worst environment and the workable depth. Due to difficulties in constructing such a high-slender leg, inaccessibility of yard fabrication equipment, etc. the construction of Jack up rig fur harsh deep sea has not been common. Method using heavy crawler crane, fabrication tower or extension by the floating crane vessel is still conventional construction but, considering high cost fur mobilizing heavy lift vessel (HLV) or additional marine work for implementing preload / full height test at sea, the ground-base construction is much advantageous. Air skidding method (ASM hereafter) is ground-based construction methodology, newly developed due to such requests. ASM could also be extended to similar engineering fields. This paper presents the operating sequence, design parameters and procedure which were verified through successful operation at the end of May 2002.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.106-113
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• 2011

Human resource theories of becoming entrepreneurs or self-employed rather than finding employment are compared as applied to fit the occupational data of technological entrepreneurs and technology jobs. The human capital theory posits that technological entrepreneurs are prepared to become a jack-of-all-trades with a variety of fields of education. Hobo theory of entrepreneurship assumes that entrepreneurs have strong taste against concentrating on a few activities, which tend to drive entrepreneurs away from employed jobs depressing their expected income. Another theory assumes that entrepreneurs have some unobserved productive qualities and abilities over employed people. Immigrant entrepreneurs could presumably be pressured out of employment under racial discrimination. Since technology jobs are mostly filled by those educated in the science and technology fields, and they presumably offer great reward to professional concentration, technological entrepreneurs may not benefit from becoming jacks-of-all-trades compared to finding employment in technological jobs income-wise. Asian immigrants in the 2000 US Census data are compared to white immigrants in technological jobs to test alternative human resource theories of entrepreneurship. Using English language ability as a proxy for the variety of education, I find in the white immigrant technological entrepreneurs support for the jack-of-all-trades theory, while in the Asian immigrant technological entrepreneurs hobo theory is supported. In the Asian technological workers only there appears the significant self-selection or comparative advantage component, while at the same time discriminatory components are significant.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.6
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• pp.407-414
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• 2023

In this study, an automated jack-up system, applicable to various fields, was employed for 3D concrete printing and developed as a simultaneous liftable 3D concrete printing system. This developed printing system enables safe and precise jack-up by monitoring the measured jack-up distance using Pearson correlation coefficient analysis and a hydraulic system with interquartile range analysis in real-time during 3D concrete printing operations. It is possible to secure the quality of 3D concrete printing structures, which is essential for expanding the application of 3D concrete printing to construct larger structures. Specimens were printed using both conventional 3D concrete printing and simultaneous liftable 3D concrete printing to evaluate the system performance. The printed specimens were investigated using a 3D scanner. The layer-wise diameter and angle of intersection of the scanned specimens were measured, and an analysis was performed to verify the advantages of the simultaneous liftable 3D concrete printing.

• Journal of the Korean association of regional geographers
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• v.10 no.4
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• pp.824-832
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• 2004

By reviewing the research papers and books about Korean geography published in China during the recent 20 years, the trend of research on the Korean geography in the filed of general and professional viewpoint was summarized in this paper. For general review, 4 major trends were observed. First, lots of research institutes have been newly established. Second, the amount of journals and books related to the Korean geography are keeping increasing. Third, a series of new academic results arc being achieved. Forth, academic exchange activities are being carried out actively in broader rangers. For professional geography study, researchers are more focused on the study of human geography rather than physical geography. And in the field of physical geography, studies about geology, earthquake and natural resource appeared livelier than others, while in human geography, studies about economic geography attract more interests. It was also observed that problems such as the research fields are limited and Jack of fundamental theory study exist. To solve these problems, the learned circles of Chinese geography should do more efforts, while an effort of introduction of achievements of Korean geography study to china by learned circles of Koran geography are also necessary.