• Publications of The Korean Astronomical Society
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• v.22 no.4
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• pp.151-168
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• 2007

We have analyzed the comet records in the Korean history books: Samguksagi, Goryeosa, and Joseonwangjosillok. For a comparison, the Chinese and Japanese comet records collected by Kronk (1999) have also been analyzed. Power spectrum of the time series of the comet records is used to find periodic comets. Statistically significant periodicities in the power spectrum are detected at the periods of 38-40 years, about 76 years, and 300-400 years for all Korean, Chinese, and Japanese comet records. We have also calculated the past orbits of some comets that have been recently observed, to check whether or not they were recorded in the history books. We use a multistep method to numerically integrate the comet's orbital motion backward in time to 51 B.C. The gravitational force due to the Sun and the nine planets, non-gravitational force, and the relativistic effects have been considered. Comparison of comet's perihelion passage time and the position on the sky with the historical records shows that the comet Halley were recorded at every passage in both Goryeo and Joseon periods. The orbital motion of the comet Pons-Brooks has also been compared with the Korean records. For the comet Tempel-Tuttle, Swift-Tuttle, and Ikeya-Zhang, we have compared our calculation of the orbital motions with those of the previous studies.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.11
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• pp.1089-1095
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• 2009

The radiated sound pressure induced by tapping test is obtained by solving the Rayleigh integral equation. For structurally radiated sound, the sound field is directly coupled to the structural motion. Therefore the impact response should be analyzed. In this paper, the delamination model is used to analyze the impact response of delaminated composite laminates. And efficient spring-mass model has been proposed to model hammer shaped impactor. Predicted sound pressure histories are compared with test data. The influence of damage on the sound pressure and impacted force history of laminates were investigated. The results show that both radiated sound pressure and impact force history are strongly influenced by delamination on laminates. As a result, it is shown that the presented sound based tapping method was found to be reliable for detecting the damage in composite laminate.

• Earthquakes and Structures
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• v.20 no.1
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• pp.97-107
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• 2021

A comprehensive study on seismic performance of wood frame building in hilly regions is presented. Specifically, seismic fragility assessment of a typical wood frame building at various locations of the northeast region of India are demonstrated. A three-dimensional simplified model of the wood frame building is developed with due consideration to nonlinear behaviour of shear walls under lateral loads. In doing so, a trilinear model having improved capability to capture the force-deformation behaviour of shear walls including the strength degradation at higher deformations is proposed. The improved capability of the proposed model to capture the force-deformation behaviour of shear wall is validated by comparing with the existing experimental results. The structural demand values are obtained from nonlinear time history analysis (NLTHA) of the three-dimensional wood frame model considering the effect of uncertainty due to record to record variation of ground motions and structural parameters as well. The ground motion bins necessary for NLTHA are prepared based on the identified hazard level from probabilistic seismic hazard analysis of the considered locations. The maximum likelihood estimates of the lognormal fragility parameters are obtained from the observed failure cases and the seismic fragilities corresponding to different locations are estimated accordingly. The results of the numerical study show that the wood frame constructions commonly found in the region are likely to suffer minor cracking or damage in the shear walls under the earthquake occurrence corresponding to the estimated seismic hazard level; however, poses negligible risk against complete collapse of such structures.

• Journal of Korean Society of Steel Construction
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• v.22 no.3
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• pp.281-291
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• 2010

In this study, a five-story steel frame was designed in accordance with KBC2005 to evaluate the effects of the beam-column connection on the structural behavior. The connections were designed as fully rigid and semi-rigid. The fiber model was used to describe the moment-curvature relationship of the steel beam and the column, the power model for the moment-rotation angle of the semi-rigid connection and the three-parameter model for the hysteretic behavior of the steel beam, column, and connection. The structure was idealized as separate 2-D frames and as connected 2-D frames. The peak ground accelerations of four earthquake records were modified in a time-history analysis for the levels of the mean return period and for the maximum base-shear force in a pushover analysis. The top story displacement, base-shear force, story drift, demanded ductility ratio for the semi-rigid connection, maximum bending moment of the column, beam, and connection, and distribution of the plastic hinge were examined in the time-history analysis. The frame with the semi-rigid connection yielded a lower base-shear force, less magnitude, and increasing ratio in the bending moment of the column, beam, and connection than the frame with a fully rigid connection. The TSD connection was deemed to have secured the economy and safety of the sample structure that was subjected to seismic excitation for the Korean design level.

• Journal of The Korean Association For Science Education
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• v.26 no.3
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• pp.317-329
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• 2006

In this research, a questionnaire was developed to investigate high school students' viewpoints, originating from science history, on 'motion of on object', the subjects were seventy- five 10th grade students and sixty-five 11th grade students. Results found that the highest percentage among the types of 10th grade students' thoughts was related to the Middle Ages 'Impetus' viewpoints. Percentages of 11th grade students' thoughts were highest for Middle Ages and Newton views. These results provided proof that the development of student thoughts' based on science history' are consistent with school year. Furthermore, student thought regarding 'object motion' under the conditions of no force, vacuum, or air under a weightless stage were related to progressive viewpoints on science history. However, the percentage of thoughts related to earlier viewpoints were considerable. Student thoughts on parabolic motion, circle motion, and conservation amount of motion were found to be highly significant in similarity to the viewpoints of Galilei, Descartes, and Huygens; view cultivated before Newton. Consequently, this study determined that educational efficiency could be raised by providing historically more progressive views to cope with conflictory student thoughts-thoughts related to past views in science history.

• Computers and Concrete
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• v.22 no.3
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• pp.305-317
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• 2018

Steel reinforced Engineered Cementitious Composite (ECC) components have been proposed for seismic structural applications, for example in coupling beams, infill panels, joints, columns, and flexural members. The development of strain in the steel reinforcement of cementitious components has been shown to vary based on both the steel reinforcement ratio and the applied deformation history. Strain in the steel reinforcement of reinforced ECC components is an important structural response metric because ultimate failure is often by fracture of the steel reinforcement. A recently proposed bond-slip model has been successfully calibrated to cyclically tested reinforced ECC beams wherein the deformation history contained monotonically increasing cycles. This paper reports simulations of two-dimensional finite element models of reinforced ECC beams to determine the appropriateness and significance of altering a phenomenological bond-slip model based on the applied deformation history. The numerical simulations with various values of post-peak bond-slip softening stiffness are compared to experimental results. Varying the post-peak bond-slip softening stiffness had little effect on the cracking patterns and hysteretic response of the reinforced ECC flexural models tested, which consisted of two different steel reinforcement ratios subjected to two different deformation histories. Varying the post-peak bond-slip softening stiffness did, however, affect the magnitude of strain and the length of reinforcing bar that strain-hardened. Overall, a numerical model with a constant bond-slip model represented well various responses in reinforced ECC beams with multiple steel reinforcement ratios subjected to different deformation histories.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.5
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• pp.148-155
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• 2011

This study analyzes stress, fatigue and vibration at clutch on the rotation of wheel. Eigenfrequencies from 1'st to 6'th order about clutch assembly are shown with the vibration at more than 800Hz. Maximum equivalent stress is shown with the frequency of 800Hz in case of the harmonic vibration applied with force. Among the cases of nonuniform fatigue loads, 'SAE bracket history' with the severest change of load becomes most unstable but 'Sample history' becomes most stable. In case of 'Sample History' with the average stress of 0MPa to $-10^5$ MPa and the amplitude stress of 0MPa to $10^5$ MPa, the possibility of maximum damage becomes 3.23%. This stress state can be shown with 6 times more than the damage possibility of 'SAE bracket history' or 'SAE transmission'. The structural result of this study can be effectively utilized with the safe design of clutch.

• Analyses & Alternatives
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• v.4 no.2
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• pp.163-202
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• 2020

This paper examines how Japanese society produced and reproduced a distinctively gendered history and memories of the experience of WWII and colonialism in the postwar era. We argue that these gendered narratives, which were embedded in postwar debates about the Peace Constitution and comfort women, have engendered contradictions and made the historical conflicts with neighboring countries challenging to resolve. On the one hand, this deepens conflict, but on the other, it also generates stability in East Asia. After Japan's defeat in WWII, the American Occupation government created the Peace Constitution, which permanently "renounces war as a sovereign right of the nation and the threat or use of force as means of settling international disputes." The removal of the state's monopoly on violence - the symbol of masculinity - resulted in Japan's feminization. This feminization led to collective forgetting of prewar imperialism and militarism in postwar Japan. While collectively forgetting the wartime history of comfort women within these feminized narratives, the conservative movement to revise the Peace Constitution attempted to recover Japan's masculinity for a new, autonomous role in international politics, as uncertainty in East Asia increased. Ironically, however, this effort strengthened Japan's femininity because it involved forgetting Japan's masculine role in the past. This forgetting has undermined efforts to achieve masculine independence, thus reinforcing dependence on the United States. Recurrent debates about the Peace Constitution and comfort women have influenced how Japanese political elites and intellectual society have constructed distinctive social institutions, imagined foreign relations, and framed contemporary problems, as indicated in their gendered restructuring of history.

• Cross-Cultural Studies
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• v.34
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• pp.115-146
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• 2014

Cyclical stories on Caucasus and Sebastopol Sketches, including War and Peace, have generally been said as masterpieces dealing with the theme of war in Leo Tolstoy's literature. Among them, it is no doubt that War and Peace is absolutely the best one describing the grand panorama of people's lives and war itself. The plot of this novel consists of the so-called Napoleonic War of 1812 and of diverse lives both from the upper class and lower class, more essentially it dramatically presents how these pictures made all literary participants experienced their destiny and lives. Throughout these texts, war, including of its cause and effects and participants, re-considers and re-evaluates all of each features. The most important themes in War and Peace is war itself as the novel's title says. Rather than a just backdrop to the novel, the war plays a significant role in providing the reader with various realistic, philosophic, moral and existentialist perspectives. Moreover, War and Peace for the writer shows contradictory two views about war; he severally criticizes the Napoleonic war of 1812 in the sense that it violets people's reason and nature. At the same time, however, Tolstoy considers that the war as liberation is justified and necessary for guarding people's nation, otechestvo in Russian. What the writer attempts to show from this novel, however, goes beyond the simple descriptions which were done above. Leo Tolstoy successfully offers and what he tries to show in the long run is that how people go through all kinds of sufferings and hardship and their spiritual resurrection, thereby leading to the vital force making history. For the writer, the essential force that makes history and people's lives is not heroic military leader like Napoleon, but those common people. And the novel serves a wonderful prelude expecting the Decembrist revolt in 1825, because all of the vital and active streams that Tolstoy emphasizes turn out true in Russian history.

• Journal of English Language & Literature
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• v.58 no.1
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• pp.21-42
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• 2012

Gloria Naylor's second novel Linden Hills (1985) explores the issues of self-exploration, empowerment, history, and memory by delineating the communal and familial tragedies and the distortion of values prevalent in a prosperous African-American urban community called Linden Hills. Drawing upon the Freud's concept of "primal scene" and "family romance," this paper aims to focus upon the Nedeed family, the founder of Linden Hills, and investigate the compelling traumatogenic force within the family, which is inseparably intertwined with the inversion of values and moral corruption permeating the entire community. The "primal crime" committed by the Nedeed ancestors serves to preserve and perpetuate a tyrannical rule by ruthless patriarchs who reign by underhanded strategies of purposefully neglecting and abusing others, including their own wives. The imprisonment, by Luther Nedeed, of his wife Willa in the family morgue epitomizes the long legacy running in the family-the oppression and burial of the pre-Oedipal, maternal history. Willa's accidental encounter, at the nadir of the family estate and her personal despair, with the faded records of the forgotten and abused Nedeed women exposes the violence-ridden ground of the family's primal scene and the absurdity of family romance the Nedeeds pursued. As the several lines of poem composed by Willie, Willa's male double, show, the hidden, forgotten history of the Nedeed women, in a sense, is the real, which cannot be assimilated to the social symbolic governed by the inhumane patriarchy of the Nedeed family and the success-oriented Linden Hills society. By portraying a catastrophic downfall of the Nedeed family and the futile outcome of its family romance, the ending of Linden Hills conveys implicitly that the contingent symbolic order and its oppressive control, however solid and invincible they may seem, can be toppled down by the real, its nameless forgotten Other.