• Transactions of Materials Processing
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• v.30 no.2
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• pp.61-68
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• 2021

As part of efforts to reduce the weight of automotive body-in-white, a hybrid center pillar with high strength 7075 aluminum alloy (AA7075) sheet and carbon fiber reinforced plastic (CFRP) has been recently studied. In the fabrication of the AA7075-CFRP hybrid center pillar, the AA7075 sheet might go through heating-forming-in-die quenching (HFQ), artificial aging, hybridizing, and then paint baking processes. In this study, we investigate the effects of the heat treatment history associated with each process on the tensile strength of the AA7075 sheet. Typical heat treatment conditions are HFQ for 20 minutes at 480℃ and then cooling down with die, artificial aging of T6 temper for 24 hours at 120℃, hybridizing for 10 minutes at 150℃, and paint baking for 20 minutes at 180℃. The tensile strength of the AA7075 sheet is continuously increased by a series of heat treatments of hybridizing and paint baking and is expected to have yield stress above 500MPa without artificial aging of T6 temper.

• Steel and Composite Structures
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• v.13 no.6
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• pp.561-570
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• 2012

Seismic collapse analysis requires efficient and automated method to perform thousands of time history analyses. The paper introduced the advantages of speed and convergence property of explicit method, provided a few techniques to accelerate speed of calculation and developed an automated procedure for collapse assessment, which combines the strong capacity of commercial explicit finite element software and the flexible, intelligent specialties of control program written in FORTRAN language aiming at collapse analysis, so that tedious and heavy work of collapse analysis based on FEMAP695 can be easily implemented and resource of calculation can be made the best use of. All the key commands of control program are provided to help analyzers and engineers to cope with collapse assessment conveniently.

• Journal of Mechanical Science and Technology
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• v.19 no.spc1
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• pp.227-236
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• 2005

Multibody system dynamics is based on classical mechanics and its engineering applications originating from mechanisms, gyroscopes, satellites and robots to biomechanics. Multibody system dynamics is characterized by algorithms or formalisms, respectively, ready for computer implementation. As a result simulation and animation are most convenient. Recent developments in multibody dynamics are identified as elastic or flexible systems, respectively, contact and impact problems, and actively controlled systems. Based on the history and recent activities in multibody dynamics, recursive algorithms are introduced and methods for dynamical analysis are presented. Linear and nonlinear engineering systems are analyzed by matrix methods, nonlinear dynamics approaches and simulation techniques. Applications are shown from low frequency vehicles dynamics including comfort and safety requirements to high frequency structural vibrations generating noise and sound, and from controlled limit cycles of mechanisms to periodic nonlinear oscillations of biped walkers. The fields of application are steadily increasing, in particular as multibody dynamics is considered as the basis of mechatronics.

• Animal Systematics, Evolution and Diversity
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• v.26 no.3
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• pp.251-260
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• 2010

We here report nine species of Tephritidae and five species of Platystomatidae from North Korea deposited in the Hungarian Natural History Museum (five new Korean records marked with asterisks): Acidiella pachypogon, Campiglossa $absinthii^*$, C. hirayamae, C. $loewiana^*$, Sphaeniscus atilius, Tephritis $brachyura^*$, Tephritis $sinensis^*$, Trupanea amoena, Xanthomyia $alpestris^*$, Rivellia alini, R. apicalis, R. asiatica, R. longialata, and R. nigroapicalis. Except for C. hirayamae, all other species are newly recorded in North Korea. As a result, a total of 22 tephritid and five platystomatid species are recognized for the North Korean tephritoid fauna. In South and North Korea together, a total of 120 nominal species of six tephritoid families are now officially recognized (1 Lonchaeidae, 1 Pallopteridae, 1 Ctenostylidae, 14 Platystomatidae, 14 Pyrgotidae, and 89 species of Tephritidae).

• Journal for History of Mathematics
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• v.30 no.1
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• pp.17-29
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• 2017

This paper is concerned with the $Ces{\grave{a}}ro$ summability of Fourier series. Many authors have studied on the summability of Fourier series up to now. Also, G. H. Hardy and J. E. Littlewood [5], Gaylord M. Merriman [18], L. S. Bosanquet [1], Fu Traing Wang [24] and others had studied the $Ces{\grave{a}}ro$ summability of Fourier series until the first half of the 20th century. In the section 2, we reintroduce Ernesto $Ces{\grave{a}}ro^{\prime}s$ life and the meaning of mathematical history for $Ces{\grave{a}}ro^{\prime}s$ work. In the section 3, we investigate the classical results of summability for Fourier series from 1897 to the mid-twentieth century. In conclusion, we restate the important classical results of several theorems of $Ces{\grave{a}}ro$ summability for Fourier series. Also, we present the research minor lineage of $Ces{\grave{a}}ro$ summability for Fourier series.

• Steel and Composite Structures
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• v.6 no.6
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• pp.479-491
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• 2006

Structures in seismic regions are designed to dissipate seismic energy input through inelastic deformations. Structural or component failure occurs when the hysteretic energy demand for a structure or component subject to an earthquake ground motion (EQGM) exceeds its hysteretic energy dissipation capacity. This paper presents a study on identifying the hysteretic energy demand and distribution throughout the height of regular steel moment resisting frames (SMRFs) subject to severe EQGMs. For this purpose, non-linear dynamic time history (NDTH) analyses were carried out on regular low-, medium-, and high-rise steel SMRFs. An ensemble of ninety EQGMs recorded on different soil types was used in the study. The results show that the hysteretic energy demand decreases from the bottom stories to the upper stories and for high-rise structures, most of the hysteretic energy is dissipated by the bottom stories. The decrease is quite significant, especially, for medium- and high-rise structures.

• Ocean and Polar Research
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• v.35 no.4
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• pp.355-371
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• 2013

The purpose of this study is to explore the history of the relationships between Japan and the Pacific Island Nations in the context of its ocean policy, and to survey the current situation. Particularly, this paper inquires into how Japan's maritime policy, nuclear policy, and official development assistance policy have affected relationships with countries in this region. Firstly, this paper gives a brief overview of the socio-political situations of Pacific Island Nations. Secondly, the history of the 'Southward Advance Theory' adopted as national policy by Japan in the Meiji era is summarized. Thirdly, how Japan successfully re-entered this region despite conflicts surrounding the nuclear issue after the Second World War is explored. Lastly, this paper investigates how official development assistance and PALM (Pacific Island Leaders Meeting) helped to develop relations between Japan and the Pacific Island Nations.

• Journal for History of Mathematics
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• v.28 no.2
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• pp.73-83
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• 2015

In this paper, we give answers to some interesting questions about a Confucian scholar and mathematician in the late Joseon Dynasty, CHOI Seok-Jeong(崔錫鼎, 1646-1715), who was inducted into the Science and Technology Hall of Fame (http://kast.or.kr/HALL) for his mathematical achievements in October, 2013. In particular, we discover that CHOI Seok-Jeong was able to devote his natural abilities and time to do research on mathematics, and that he frequently communicated with his friend and fellow scholar, LEE Se-Gu(李世龜, 1646-1700), who was an expert on the astronomical calendar and mathematics, based on at least 24 letters between the two.

• Journal of Mechanical Science and Technology
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• v.18 no.12
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• pp.2125-2136
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• 2004

In this paper, a numerical application algorithm for applying the CFAM (Consistent Fluid Added Mass) matrix for a core seismic analysis is developed and applied to the 7-ducts core system to investigate the fluid effects on the dynamic characteristics and the seismic time history responses. To this end, three cases such as the in-air condition, the in-water condition without the fluid coupling terms, and the in-water condition with the fluid coupling terms are considered in this paper. From modal analysis, the core duct assemblies revealed strongly coupled out-of-phase vibration modes unlike the other cases with the fluid coupling terms considered. From the results of the seismic time history analysis, it was also verified that the fluid coupling terms in the CFAM matrix can significantly affect the impact responses and the seismic displacement responses of the ducts.

• Journal of the Korean Applied Science and Technology
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• v.38 no.4
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• pp.1195-1208
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• 2021

This study aims to find the fundamental problem of skepticism as a PE teacher. For above, a PE teacher, Jun-ho Lee is selected as a participant of this study and used the life history method. Based on the result of above, the contents of 1) 'Stereotype and subculture', 2) 'Changing in discipline.', 3) 'Confusion and self-accusation', 4) 'Ordinary teacher, not a true teacher' is drawn. This result shows that the skepticism concerned the teacher can be explained as 'irony of change' and it is confirmed that this is originated by the fundamental background as 'simultaneity of non-simultaneous'. In conclusion, the emotional exhaustion due to the inconsistency of 'simultaneity of non-simultaneous' existing in the school is inevitable consequence, and on the other hand, it shows that he is an ordinary PE teacher and it helps to understand the life and worry of ordinary PE teachers in Korean society.