• Korean Journal of Heritage: History & Science
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• v.47 no.4
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• pp.192-209
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• 2014

The important national cultural heritages were retrieved. April 25 2014, US President Barack Obama formally returned 9 Seals of Joseon Dynasty and Korean Empire in Korea-US Summit taken place in Cheong Wa Dae. These Seals were taken out of Deoksugung illegally by a US Marine Corps officer during Korean War, handed down to his posterity, and last November 2013 confiscated by HSI in San Diego. Through investigations above facts turned out and it was decided to return these relics to Koera. In the process of surveying these seals, I confimed the authenticity of them and transferred my opinion to Cultural Heritage Administration. In this paper, I try to summarize the historical value of each Seals and suggest the remaining task.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.5
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• pp.487-495
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• 2014

In this study, in order to suggest the design method for supports in the room-and-pillar underground structure, the case study was carried out. In the case study, shape of rock pillar and room was mainly considered. From the analysis, a displacement at the roof, the maximum principle stress and plastic state were examined. To optimize variables in the case study, cases from the Seoul metro station were analyzed, then a target depth of the underground structure and ground conditions were determined. And the height of rock pillar and room were chosen from the assumed purpose of underground space, i.e. living/office and warehouse. Total cases of analysis was 180 cases including 3 types of ground condition, 5 types of rock pillar and 6 types of roof span. It is expected that results from analysis can be used to determine the installation of support in room-and-pillar underground structure with stability, utilization efficiency of underground space and applicability of vehicles.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.6
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• pp.511-524
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• 2016

Since a room-and-pillar underground structure is characterized by its grid-type array of room and pillar, its economical efficiency can be governed by excavation sequence. In this study, the construction period by the drill-and-blast method as a excavation method for a room-and-pillar underground structure was examined. In addition, the parallel excavation sequence was considered as the main sequence of a room-and-pillar underground structure. Sequences of mucking and support installation were derived to estimate the total excavation cycle by taking the case of a road tunnel into consideration. From the excavation cycle of room-and-pillar underground structure, the relationship between available maximum and minimum numbers of jumbo drill machines depending on the number of faces in operation was suggested.