• Clean Technology
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• v.15 no.3
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• pp.172-179
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• 2009

The thermoplastic polyurethane waste (TPU-S) with good tensile properties, hardness, NBS abrasion resistance, specific gravity and low wet coefficient of kinetic friction was melt-blended with ethylene propylene diene monomer rubber (EPDM) with high wet slip resistance and low mechanical properties to form EPDM/TPU-S blend films, and their composition-property relationship was investigated to find the optimum composition for shoe outsole material. The properties except the wet slip resistance increased with increasing TPU-S contents in the blend. All the properties except elongation at break, specific gravity and the wet coefficient of kinetic friction in the range of $0{\sim}65\;wt%$ of TPU-S did not attain the values predicted by the simple additive rule. The optimum weight ratio of EPDM/TPU-S for the application to the typical shoe outsole material was found to be 30/70.

• Journal of Adhesion and Interface
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• v.24 no.4
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• pp.124-130
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• 2023

For automotive coating agents that require little change in characteristics due to changes in external temperature, changes in noise characteristics due to changes in the external environment are very important. Therefore, soft polyurethane with excellent cold resistance, weather resistance, and abrasion resistance, and polysiloxane whose -OH terminated and side chains are modified with amines, are widely used. In this study, coating agents was prepared by adding water-born polyurethane, polysiloxane, ultra high molecular weight polypropylene (UHMWPP) powder, carbon black, and a matting agent to determine the effect of each resin component on noise. To study the effect of each resin component on noise, a coating agent was prepared by adding water-born polyurethane, polysiloxane, UHMWPP powder, carbon black, and a matting agent. The hard/soft segment ratio of water-born polyurethane, the main component of the coating, was 27.1%/72.9%, and the ratio of amino siloxanes to hydroxy-terminated polysiloxane was 2:7, which produced the least noise. The difference in friction coefficient was large when the friction body moves at high speed. When UHMWPP powder replaced SiO₂, noise decreased and gloss also decreased.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.1
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• pp.54-66
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• 2001

The aim of this study was to investigate the fluoride release and some mechanical properties including 3-point bending strength, amount of abrasion, surface hardness, water sorption/solubility and cytotoxicity of the newly developed composite resins containing 8, 16, 24 wt% $SrF_2$ glass filler (VF8, VF16, VF24) and four commercially available composite resins, Heliomolar(HE), Verdonfil(VE), Z100(ZH) and Aelitefil(AE). To investigate cytotoxic effect, agar overlay assay was done. Amount of fluoride released into distilled water was measured over a 62-days period from VF8, VF16, VF24 and HE. Results were as follows: 1. Experimental composite resins showed similar mechanical properties to commercial composite resins, but 3-point bending strength and surface hardness of experimental composite resins were inferior to ZH. 2. Over a 62-day Period, the amount of fluoride released was ordered: VF24>VF16>VF8>HE. In experimental composite resins, the amount of fluoride released was 9-23 times greater than HE and seemed to be proportional to the content of $SrF_2$ glass filler. 3. Experimental composite resins and all control composite resins showed mild cytotoxicity. This study showed significantly greater fluoride release from newly developed composite resins than control(HE) and addition of $SrF_2$ glass filler did not decrease mechanical properties or increase cytotoxicity of composite resin. The results from this study imply that newly developed composite resin have adequate mechanical properites, mild cytotoxicity and some potential for secondary caries prevention.

• Journal of Bio-Environment Control
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• v.4 no.1
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• pp.59-67
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• 1995

This study was conducted to develope the automatic insulation system which control inside temperature of the greenhouse. For this purpose, the double- wall greenhouse and system which could automatically supply and discharge styrene pellets were constructed and abrasion of the pellets, blower ability, insulating property, transmittance and shading effect were analyzed by the experiments. The results obtained from this study can be summarized as follows : 1. It took an hour and fifteen minutes to supply and discharge about 2㎥ pellets in the experimental greenhouse. However, it is possible to reduce the operation time by proper selection of the blower and exhaust port, and by proper control of the supply and return pipe. 2. It was founded that the indirect delivery way was more profitable than the direct one in the supply and return of pellets. 3. When the transmittance was measured between 10 a.m. and 3 p.m., the average light transmissivity rate was 67%. 4. In winter nighttime, the inside temperature of the double- wall greenhouse with out the pellets was higher than the outside temperature by 3.4$^{\circ}C$ on an average. However, the inside temperature of the double - wall greenhouse with insulated area 73% was higher than the outside by one 6.6$^{\circ}C$ on an average, and the inside temperature of the greenhouse with insulated area 100% was higher than outside one by 13.5$^{\circ}C$ on an average. Therefore, it was proved that the insulating ability of the double - wall greenhouse in nighttime was excellent. 5. When the outside temperature was 36.9$^{\circ}C$ on an average, the inside temperature of the double- wail greenhouse with insulated area 100% was 3$0^{\circ}C$ on an average. As the inside temperature was lower than the outside one by 7$^{\circ}C$ on an average, we could know that the shading effects of the double- wall greenhouse were excellent in summer daytime.

• 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.