• Korean Journal of Heritage: History & Science
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• v.54 no.2
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• pp.22-37
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• 2021

The wind chime is a longstanding Jangeomgu (majestic article) found in Korea, China, and Japan. However, basic research on wind chimes is currently inadequate as it is difficult to estimate the time of production, and there are few relics. Therefore, this research morphologically classifies the eight bronze wind chimes decorating the baldachin of the Stone Standing Maitreya Bodhisattva of Gwanchoksa Temple, Nonsan. Based on this, the manufacturing techniques and production period are scientifically demonstrated. The synthesis of the research results reveals that the structure and characteristics of the wind chimes of the Stone Standing Maitreya Bodhisattva of Gwanchoksa Temple, Nonsan differ depending on their location on the baldachin. The four large-sized wind chimes on the lower-baldachin were manufactured by casting a Cu-Sn-Pb alloy, and they are estimated to have been made during the early period of Goryeo. The two medium-sized wind chimes of the upper-baldachin's northern direction were manufactured through forging a Cu-Sn or Cu-Sn-Pb alloy, and they appear to have a similar structure to the cylindrical wind chimes appearing during the latter period of Goryeo and the Joseon period. The two small-sized wind chimes of the upper-baldachin's southern direction were manufactured by casting a Cu-Sn-Pb alloy containing Zn, and based on the chemical composition of the alloy and the shape of the clapper, they are estimated to have been manufactured during the latter period of Joseon. Through the observation of microstructures and a chemical composition analysis, it is demonstrated that two wind chimes of the lowerbaldachin were manufactured by casting and slow cooling the alloy with an alloy ratio of Cu:Sn:Pb≒80:15:5. In addition, it is estimated that the wind chimes of the upper-baldachin's northeast direction were manufactured by forging an alloy of Cu-Sn with a similar alloy ratio to that of forged high tin bronze. The results of a comparative analysis of prior research on domestic wind chimes confirm that two wind chimes of the lower-baldachin have a similar composition ratio to the wind chime excavated from Wolnamsaji in Gangjin, containing an amount of tin that corresponds with ancient records. Having a similar alloy ratio to forged high tin bronze, the wind chimes of the upper-baldachin's northeast direction are the only instances among all of the wind chimes that have been examined to date that were manufactured using this forging method. The purpose of this research is to collect baseline data to verify and classify the manufacturing period of wind chimes according to their morphological characteristics based on scientific evidence. It is hoped that this data can be utilized for the restoration and conservation processes of the wind chimes of the Stone Standing Maitreya Bodhisattva of Gwanchoksa Temple, Nonsan.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.2
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• pp.197-206
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• 2023

Recently, the international community, including the International Maritime Organization (IMO), has strengthened regulations on air pollution emissions of ships, and eco-friendly ships are actively being developed to reduce exhaust gas emissions. Among them, rotor sail (RS), a wind-assisted ship propulsion system, is attracting attention again. RS is a cylindrical device installed on the ship deck, that generates hydrodynamic lift using a magnus effect. This is a next generation eco-friendly auxiliary propulsion technology, and Enercon company, which developed RS-applied ships, announced that fuel savings of more than 30% are possible. In this study, optimal installation conditions such as RS spacing and arrangement type were selected when multiple RSs were installed on ships. AR=5.1, SR=1.0, and D_e/D was fixed at 2.0 according to the RS arrangement, and the wind direction was considered only for the unidirectional +y-axis. Regarding arrangement conditions, five conditions were set at 3D intervals in the +x-axis direction from 3D to 15D and five conditions in the +y-axis direction from 5D to 25D. C_L, C_D and aerodynamic efficiency (C_L/C_D) were compared according to the square(□) and diamond(◇) shape arrangements. Consequently, the effect of RS on the longitudinal distance was not significantly different. However, in the case of RS flow characteristics according to the transverse distance, the interaction effect of RS was the greatest when the two RSs almost matched the wind direction. In the case of the RS flow characteristics according to the arrangement, notably, when the wind blew in the forward (0°) direction, the diamond (◇) arrangement was least affected by the backward flow between RSs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.6
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• pp.423-446
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• 2023

Shield TBM tunnel linings are segmented into segments and rings. This study investigates the response characteristics of the stress and displacement of the segment lining under seismic waves through modeling that considers the interface behavior between segments by applying a shell interface element to the contact surface between segments and rings. And there is no management criteria for ovaling deformation of segment linings in Korea. So, this study the ovality criteria and meaning of segment lining. The results of study showed that the distribution patterns of stress and displacement under seismic waves were similar between continuous linings and segment linings. However, the maximum values of stress and displacement showed differences from segment linings. The stress distribution of the continuous lining modeled as a shell type has a stress distribution that has continuity in the 3D cylindrical shape, but the segment lining is concentrated outside the segment, and the largest stress occurs at the location where the contact surface between the segment and the ring is concentrated. This intermittent and localized stress distribution shows an increasing as the ovality of the lining increases at seismic waves. The ovality at which the increase in stress distribution begins to show irregularity and localization is about 150‰. Ovality of 150‰ is an unrealistic value that cannot represent actual lining deformation. Therefore, the ovality of the segment lining increase with depth, but it does not have a significant impact on the stability caused by seismic load.