• Korean Journal of Heritage: History & Science
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• v.45 no.2
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• pp.72-99
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• 2012

Cheomseongdae, Korea's so-called "star-gazing tower" located in the former Silla Dynasty capital of Gyeongju, is generally believed to have maintained its original shape since its construction in 647. The stone structure was closely examined and measured by Gyeongju National Museum in 1962 and reexamined by Korean National Research Institute of Cultural Heritage in 2009. This research noted the following structural anomalies of Cheomseongdae. A corner of the top rectangle layer was broken diagonally in a form that can never be attributed to a natural cause. The four metal clamps under the top rectangle layer had been missing. Four grooves, with unknown usage, exist on the sides of the long rectangular stones projected out of the circular body at the second and third circular layers from the top. On the second circular layer from the top, there are three flat stones, less than a half as tall as their surrounding stones. The average height of the third circular layer from the top is only 23.5 cm, while the overall average of the entire 27 circular layers is 29.9cm. This research postulates that all these anomalies are due to prior destructions and improper restorations of the structure. The first destruction and restoration of Cheomsengdae was likely to have occurred before the mid 15th century. The damages might include a pavilion on the top of the structure and a stone with the name of the structure carved in. The Mongolian invasion in the 13th century was a most likely cause. After the restoration, the structure suffered at least another attack. The damages on the top layer and the missing iron clamps were due to the later attack. The grooves and flat stones were to house holding device that affixed certain objects to the outer surface of the circular body. The metal or stone objects might have faced upward at the four corners of Chemseongdae, bridging the gaps between the rectangle layers and circular layers. The current Chemseongdae lost at least the four affixed objects, four holding devices, and one flat stone.

• The Journal of the Korean dental association
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• v.50 no.7
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• pp.384-393
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• 2012

Successful treatment of a badly broken down tooth with pulpal disease depends not only on good endodontic therapy, but also on good prosthetic reconstruction of the tooth after endodontic therapy is completed. The ideal treatment of endodontically treated teeth has been widely and controversially discussed. Endocrown is a restorative option for endodontically treated teeth. Endocrown design incorporates the core and short post into the crown as a single restoration. The preparation of endocrown consists of a circular equigingival butt-joint margin and central retention cavity of the entire pulp chamber instead of employing intraradicular posts. This design significantly increases the surface area of the preparation available for cementation. It is particularly useful in young patient teeth for long-term provisional restoration and in teeth with short clinical crowns. This technique represents a promising and conservative method for the treatment of endodontically treated teeth that require long-term protection and stability. Endocrown can be considered as a feasible alternative to full crowns or composite overlays for the restoration of non vital teeth.

• Journal of Korea Water Resources Association
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• v.54 no.1
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• pp.15-25
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• 2021

The purpose of this study was to present the necessity and effect of culvert fishway, based on the absence of design criteria for it which fishes can pass. As an attempt for this purpose, circular culvert fishway were designed hydraulically to meet the passage condition for selected target fish species, and post-monitoring was performed to confirm its effectiveness. In the case of general circular culvert without weir baffles, the target fish species cannot pass because of the constant depth and velocity in the entire reach of the circular culvert, so it was confirmed that resting pools must be installed to help fish passage. In the case of circular culvert with weir baffles, the depth and the mean velocity in resting pool increased by about 240% and decreased by about 70% respectively, which not only satisfied the passage conditions of Zacco platypus that can swim at more than 10 times the speed of body length for 1 to 5 seconds, but also confirmed that various river fish could pass. Post-monitoring results of the restoration reach and fish capture monitoring surveys of circular culvert fishway demonstrated that the target fish species, Zacco platypus, can pass through it.

• Journal of IKEEE
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• v.22 no.1
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• pp.68-73
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• 2018

In this paper, we propose an efficient algorithm for mapping a $360^{\circ}$ circular image to a planar image. The proposed algorithm consists of obtaining size of the planar image, calculating the distance between the camera and the planar image, calculating horizontal angle of camera and planar image, calculating vertical angle between camera and planar image, calculating the position of a pixel that matches pixels in a $360^{\circ}$ circular image to pixels in a planar image. Experiments were performed to evaluate the efficient algorithm for mapping the proposed $360^{\circ}$ circular image to the plane image. The reconstruction rate of the mapped plane image was confirmed 99% and the image quality of the mapped plane image was confirmed 72%. Since the results were higher than the standard values of commercial software, the effectiveness of the algorithm was confirmed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2017.11a
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• pp.206-208
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• 2017

In recent years, we have been working on the improvement project of mercury 3-lecture type at the Geummundo lighthouse for more than 100 years. We have installed toxic mercury removal, LED light source, and dualization system for nonstop. It can be seen as an example. Circular restoration of the entire frame is performed, and the real-time status can be grasped through the installation of the double-ball bearing and the remote control system. After installation, optical measurement through Hanvit secured the optical performance of 2,000,000 cd of floating brightness of 300cd, proving the efficient possibility of introducing the domestic rotary type light source using LED light source.

• Journal of the korean academy of Pediatric Dentistry
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• v.46 no.1
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• pp.111-118
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• 2019

Post-endodontic restorations are both important and challenging for clinical success in endodontically treated posterior teeth. Several options have been proposed to restore endodontically treated molars. In pediatric dentistry, restoration using conventional single crowns, especially for partially erupted molars with insufficient retentive tooth structure, has proven to be difficult. However, the endocrown presents a conservative and esthetic restorative alternative to conventional crowns with post-and-core, as it acquires additional retention within the pulp chamber. The tooth preparation consists of a circular, equigingival, butt-joint margin and a central retention cavity in the pulp chamber that helps to construct both the crown and core as a single unit. This case report describes the esthetic and conservative endocrown restorations of erupting permanent first molars with extensive coronal destruction.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.1
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• pp.32-43
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• 2009

The purpose of this study is to suggest the visual landscape plan for Shinan province with ecological landscape resources, which is comprised of more than 1,000 islands. The plan was done by the order of image plan, landscape structure plan and detained landscape plan. The image of Shinan province was elicited as 'nature', 'complexity' and 'connectivity', by the aspects of planning, cognitive and strategic sides. The landscape zones are planned, such as leisure zone, rural & marine ecological zone and marine tourism zone, and the landscape axes are also set, such as marine axis, ecological axis and circular axis. Especially to conserve the ecological resources, some conservation zones are proposed and design guidelines for each landscape type are also provided, which are not commonly included in the urban landscape plan. Consequently, the landscape plan and ecological environmental plan were complementary to each other. In the detailed landscape plan, more specific plans and design guidelines are suggested for coastal scenery, village and forest scenery, historical and cultural landscape management and promotion. To improve the visual landscape in terms of planning and administrative aspects, the visual landscape plan has become increasingly important for the local governments. The establishment of visual landscape plan may hopefully help to make Shinan province more beautiful and attractive. The landscape plan and ecological environment plan should be integrated, and the further discussion and research are necessary.

• Archives of Plastic Surgery
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• v.44 no.5
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• pp.370-377
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• 2017

Background Composite grafts are frequently used for facial reconstruction. However, the unpredictability of the results and difficulties with large defects are disadvantages. Adipose-derived stem cells (ADSCs) express several cytokines, and increase the survival of random flaps and fat grafts owing to their angiogenic potential. Methods This study investigated composite graft survival after ADSC injection. Circular chondrocutaneous composite tissues, 2 cm in diameter, from 15 New Zealand white rabbits were used. Thirty ears were randomly divided into 3 groups. In the experimental groups (1 and 2), ADSCs were subcutaneously injected 7 days and immediately before the operation, respectively. Similarly, phosphate-buffered saline was injected in the control group just before surgery in the same manner as in group 2. In all groups, chondrocutaneous composite tissue was elevated, rotated 90 degrees, and repaired in its original position. Skin flow was assessed using laser Doppler 1, 3, 6, 9, and 12 days after surgery. At 1 and 12 days after surgery, the viable area was assessed using digital photography; the rabbits were euthanized, and immunohistochemical staining for CD31 was performed to assess neovascularization. Results The survival of composite grafts increased significantly with the injection of ADSCs (P<0.05). ADSC injection significantly improved neovascularization based on anti-CD31 immunohistochemical analysis and vascular endothelial growth factor expression (P<0.05) in both group 1 and group 2 compared to the control group. No statistically significant differences in graft survival, anti-CD31 neovascularization, or microcirculation were found between groups 1 and 2. Conclusions Treatment with ADSCs improved the composite graft survival, as confirmed by the survival area and histological evaluation. The differences according to the injection timing were not significant.

• Korean Journal of Heritage: History & Science
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• v.53 no.4
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• pp.100-117
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• 2020

National Treasure no. 101, the stupa of State Preceptor Jigwang from the Beopcheonsa Temple Site in Wonju has been transferred from place to place and reassembled several times since it was built. In particular, overall dismantling and repair was carried out in 1957 to restore parts damaged by bombing during the Korean War. Documented information on the repair process and materials used at that time does not exist. However, various types of metal materials used for this stupa have been identified during conservation work. Besides clamps anchor bolts, 9mm-thick circular rebars were mainly used for joining the parts of this stupa, while circular rebars and wires of various thicknesses were used for joining the parts with mortar restoration materials. Although deformed bars are typically used for stone pagodas classified as architectural structures, smooth circular rebars were used in this case. In terms of restoration using mortar, material shapes were transformed, bound alternately, and twisted irregularly to improve bonding strength and coherence in order to insert restoration materials and to bolster structural weaknesses. In addition, metallographic analysis showed the material to be hypo-eutectoid steel with low carbon content. Many non-metallic inclusions in the shape of drops of different sizes were included, which do not affect the whole elemental composition due to the very small quantities involved. Qualitative and EPMA analysis of Mn and S, which were not identified by SEM-EDS area analysis, established an even distribution of MnS in crystal grains of the microstructure, regardless of the shape of the samples. It is presumed that secondary homogenization and softening might have been conducted after manufacturing to facilitate the working process. Furthermore, in consideration of properties indicating that the thinner the steel is, the less carbon content contained and the greater the elasticity and elongation, it is judged that restoration work was ordered.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.136-146
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• 1999

The purpose of this study was to estimate the changes of marginal adaptation to the cavity floor of light-cured glass ionomer cement base after application of a composite restoration. Eighty non-carious extracted human molars were used in the present study. Circular cavities were prepared on the center of the exposed dentin surface to 0.5mm, 1.0mm, 1.5mm, 2.0mm in depth and the prepared cavities were pretreated with Dentin conditioner and filled with Fuji II LC(GC Int. Co., Japan). They randomly assigned into 3 groups according to the difference in application of a composite restoration; Group 1(control group): only glass ionomer base, Group 2: The application of a composite restoration surrounded by dentin with class I cavity over glass ionomer base after conventional dentin bonding to the exposed dentin and glass ionomer base, Group 3: The application of composite restoration not-surrounded by dentin over glass ionomer base after conventional dentin bonding to the exposed dentin and glass ionomer base. To examine the interface between cavity floor and light-cured glass ionomer cement base, each groups were sectioned vertically through the center of restorations with diamond saw and the gap size(${\mu}m$) of interface measured by SEM. The results were analyzed by using One Way ANOVA. The results were as follows: 1. Good adaptation between glass ionomer cement base and cavity floor was showed in specimens with 0.5mm, 1.0mm depth base of control group. But in specimens with 1.5mm, 2.0mm depth base of control group, the gap was measured about $15{\mu}m$, $40{\mu}m$ respectively. 2. Gap size in group 2 was significantly higher than that in control group(P<0.05). 3. Gap size in group 3 was significantly higher than that in control group and group 2(P<0.05). 4. It was possible to observe the good adaptation between glass ionomer cement base and dentin which was intermediated with 4-10${\mu}m$ hybrid layer in specimens with 0.5mm, 1.0mm depth base of control group. Cohesive fracture within cement base was observed in all specimens which had the gap between glass ionomer cement base & dentin. 5. It was possible to observe the gap formation between cement base and bonding agent and between composite resin and dentin in all specimens of group 2.