• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.5
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• pp.419-426
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• 2018

For an orbit transfer in a space exploration mission, a solid or liquid rocket booster is included at the last stage of the launch vehicle. During the orbit transfer, thrust misalignment can cause a severe orbit error. Three axis attitude control or spin stabilization can be implemented to minimize the error. Spin stabilization technique has advantages in structural simplicity and lightness. One of ways to apply the spin stabilization to the payload is to include a spin table system in the launch vehicle. In this paper, effect of the spin table system on separation dynamics of the payload is analyzed. Simple model of the spin table to mimic basic functions is designed and simulation environment is established with the model. Effect of the spin table is tested by evaluating separation dynamics of a payload with and without the spin table. Analysis on tolerance effect of separation spring constant on separation dynamics of a payload is conducted.

• MISULJARYO - National Museum of Korea Art Journal
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• v.100
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• pp.50-80
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• 2021

This paper critically examines the history of the theories connected to the Wongaksa Temple Pagoda that have developed over the last 100 years focusing on the original number of stories the pagoda would have reached. Part II of this paper retraces the dynamic process of the rediscovery of the Wongaksa Temple Pagoda by Westerners who traveled to Korea during the port-opening period. Koreans at the time viewed the Wongaksa Temple Pagoda as an object of no particular appeal or even as an eyesore. However, Westerners appreciated it as a wonder or magnificent sight. Since these Westerners had almost no prior knowledge of Buddhist pagodas, they were able to write objective travelogues. At the time, these visitors generally accepted the theory common among Joseon intellectuals that Wongaksa Temple Pagoda once had thirteen stories. Part III focuses on Japanese government-affiliated scholars' academic research on the Wongaksa Temple Pagoda after the proclamation of the Korean Empire and the Japanese Government-General of Korea's subsequent management of the pagoda as a cultural property during the colonial era. It also discusses issues with Japanese academic research and management. In particular, this portion sheds light on the shift in theories about the original number of stories of the Wongaksa Temple Pagoda from the ten-story theory supported by Sekino Tadashi (關野 貞), whose ideas have held a great influence on this issue over the last 100 years, to the thirteen-story theory and then to the idea that it had more than thirteen. Finally, Part IV addresses the change from the multi-story theory to the ten-story theory in the years after Korea's liberation from Japan until 1962. Moreover, it highlights how Korean intellectuals of the Japanese colonial era predominantly accepted the thirteen-story theory. Since 1962, a considerable quantity of significant research on the Wongaksa Temple Pagoda has been published. However, since most of these studies have applied the ten-story theory suggested in 1962, they are not individually discussed in this paper. This retracing of the history of theories about the Wongaksa Temple Pagoda has verified that although there are reasonable grounds for supporting the thirteen-story theory, it has not been proved in the last 100 years. Moreover, the number of pagoda stories has not been fully discussed in academia. The common theory that both Wongaksa Temple Pagoda and Gyeongcheonsa Temple Pagoda were ten-story pagodas was first formulated by Sekino Tadashi 100 years ago. Since the abrasion of the Wongaksa Temple Stele was so severe the inscriptions on the stele were almost illegible, Sekino argued that the Wongaksa Temple Pagoda was a ten-story pagoda based on an architectural analysis of the then-current condition of the pagoda. Immediately after Sekino presented his argument, a woodblock-printed version of the inscriptions on the Wongaksa Temple Stele was found. This version included a phrase that a thirteen-story pagoda had been erected. In a similar vein, the Dongguk yeoji seungnam (Geographic Encyclopedia of Korea) published by the orders of King Seongjong in the late fifteenth century documented that Gyeongcheonsa Temple Pagoda, the model for the Wongaksa Temple Pagoda, was also a thirteen-story pagoda. The Wongaksa Temple Stele erected on the orders of King Sejo after the establishment of the Wongaksa Temple Pagoda evidently shows that Sekino's ten-story premise is flawed. Sekino himself wrote that "as [the pagoda] consists of a three-story stereobate and a ten-story body, people call it a thirteen-story pagoda," although he viewed the number of stories of the pagoda body as that of the entire pagoda. The inscriptions on the Wongaksa Temple Stele also clearly indicate that the king ordered the construction of the Wongaksa Temple Pagoda as a thirteen-story pagoda. Although unprecedented, this thirteen-story pagoda comprised a ten-story pagoda body over a three-story stereobate. Why would King Sejo have built a thirteen-story pagoda in an unusual form consisting of a ten-story body on top of a three-story stereobate? In order to fully understand King Sejo's intention in building a thirteen-story pagoda, analyzing the Wongaksa Temple Pagoda is necessary. This begins with the restoration of its original name. I disprove Sekino's ten-story theory built upon flawed premises and an eclectic over-thirteen-story theory and urge applying the thirteen-story theory, as the inscriptions on the Wongaksa Temple Stele stated that the pagoda was originally built as a thirteen-story pagoda.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.2
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• pp.121-143
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• 2010

To investigate the effect of implant types and bone resorption on the fracture characteristics. 4 types of Osstem$^{(R)}$Implant were chosen and classified into external parallel, internal parallel, external taper, internal taper groups. Finite elements analysis was conducted with ANSYS Multi Physics software. Fatigue fracture test was performed by connecting the mold to the dynamic load fatigue testing machine with maximum load of 600N and minimum load of 60N. The entire fatigue test was performed with frequency of 14Hz and fractured specimens were observed with Hitachi S-3000 H scanning electron microscope. The results were as follows: 1. In the fatigue test of 2 mm exposed implants group, Tapered type and external connected type had higher fatigue life. 2. In the fatigue test of 4 mm exposed implants group, Parallel type and external connected types had higher fatigue life. 3. The fracture patterns of all 4 mm exposed implant system appeared transversely near the dead space of the fixture. With a exposing level of 2 mm, all internally connected implant systems were fractured transversely at the platform of fixture facing the abutment. but externally connected ones were fractured at the fillet of abutment body and hexa of fixture or near the dead space of the fixture. 4. Many fatigue striations were observed near the crack initiation and propagation sites. The cleavage with facet or dimple fractures appeared at the final fracture sites. 5. Effective stress of buccal site with compressive stress is higher than that of lingual site with tensile stress, and effective stress acting on the fixture is higher than that of the abutment screw. Also, maximum effective stress acting on the parallel type fixtures is higher. It is careful to use the internal type implant system in posterior area.