• Restorative Dentistry and Endodontics
• /
• v.22 no.1
• /
• pp.428-446
• /
• 1997

Restorative procedures can lead to weakening tooth due to reduction and alteration of tooth structure. It is essential to prevent fractures to conserve tooth. The resistance to fracture of the restored tooth may be influenced by many factors, among these are the cavity dimension and the physical properties of the restorative material. The placement of direct composite resin restorations has generally been found to have a strengthening effect on the prepared teeth. It is the purpose of this investigation to study the relationship between the cavity isthmus and the fracture resistance of a tooth in composite resin restorations. In this study, MO cavity was prepared on maxillary first premolar. Three dimensional finite element models were made by serial photographic method and isthmus(1/4, 1/3, 1/2 of intercuspal distance) were varied. Two types of model(B and R model) were developed. B model was assumed perfect bonding between the restoration and cavity wall and R model was left unfilled. A load of 500N was applied vertically at the first node from the lingual slope of the buccal cusp tip. This study analysed the displacement, 1 and 2 direction normal stress and strain with FEM software ABAQUS Version 5.2 and hardware IRIS 4D/310 VGX Work-station. The results were as follows : 1. Displacement of buccal cusp in R model occurred and increased as widening of the cavity, and displacement in B model was little and not influenced by cavity width. 2. There was a significant decrease of stress resulting in increase of fracture resistance in B model when compared with R model. 3. With the increase of the isthmus width, B model showed no change in the stress and strain. In R model, the stress and strain increased both in the area of buccal-pulpal line angle and the buccal side of marginal ridge, therefore the possibility of crack increased. 4. The stress and strain were distributed evenly on the tooth in B model, but in R model, were concentrated on the buccal side of the distal marginal ridge and buccal-pulpal line angle, therefore the possibility of fracture increased.

• Journal of Korean Society for Geospatial Information Science
• /
• v.20 no.3
• /
• pp.11-18
• /
• 2012

Increasing concern about biodiversity has lead to a rise in demand on the spatial assessment of biological resources such as biodiversity assessment, protected area selection, habitat management and restoration in Korea. The purpose of this study is to create species richness map through data collection and modeling techniques for wildlife habitat assessment. The GAM (Generalized Additive Model) is easy to interpret and shows better relationship between environmental variables and a response variable than an existing overlap analysis and GLM (Generalized Linear Model). The study area delineated by a large watershed contains Jirisan national park, Mt. Baekun and Sumjin river with three kinds of protected areas (a national park, a landscape ecology protected area and an otter protected area). We collected the presence-absence data for wildlife (mammals and birds) using a stratified random sampling based on a land cover in the study area and implemented natural and socio-environmental data affecting wildlife habitats. After doing a habitat use analysis and specifying significant factors for each species, we built habitat suitability models using a presence-absence model and created habitat suitability maps for each species. Biodiversity maps were generated by taxa and all species using habitat suitability maps. Significant factors affecting each species habitat were different according to their habitat selection. Although some species like a water deer or a great tit were distributed at the low elevation, most potential habitats for mammals and birds were found at the edge of a national park boundary or near a forest around the medium elevation of a mountain range. This study will be used for a basis on biodiversity assessment and proected area selection carried out by Ministry of Environment.

• Journal of Wetlands Research
• /
• v.16 no.2
• /
• pp.251-259
• /
• 2014

Recently, wetland and paddy wetland are being highlighted as the international environmental issues. However, research system which can assess paddy wetland is lacking. Thus, the purpose of this study is to assess the value of paddy wetland by applying RAM to paddy wetland. In addition, we would like to use this study as the data to establish assessment method for paddy wetland. 16 sites were selected as research targets based on altitude and soil. As the results of wetland assessment, 16 research target sites had total score of 212~227 and the average of 2.17~2.50. It was similar to those of Lacustrine Wetlands, Palustrine Wetland and Riverine Wetland which were sites in previous studies. The value could be recognized as the wetland. However, there was no difference in assessment results based on altitude and soil. It was found that all conservation values were the same. The factor the most closely affecting conservation value was the area. However, there was limitation to apply existing wetland assessment system to paddy wetland. In order to assess paddy wetland, factors such as rice farming methods, topography, vegetation, growth environment and biodiversity should be added. It was thought to supplement wetland assessment system through various further studies.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.15 no.1
• /
• pp.99-118
• /
• 2012

The aim of this study is to define a correlation between spatial distribution characteristics of FFG(Functional Feeding Groups) of aquatic insects and related environmental factors in the Geum River based on the theory of RCC(River Continuum Concept). For that objective we had used SMRA(Stepwise Multiple Regression Analysis) method to analyze close relationship between the distribution of aquatic insects and the physical and chemical factors that may affect their inhabiting environment in the study area. And then, a probabilistic method named Frequency Ratio Model(FRM) and spatial analysis function of GIS were applied to produce a predictive distribution map of biota community considering their distribution characteristics according to the environmental factors as related variables. As a result of SMRA, the values of decision coefficient for factors of elevation, stream width, flow velocity, conductivity, temperature and percentage of sand showed higher than 0.5. Therefore these 6 environmental factors were considered as major factors that might affect the distribution characteristics of aquatic insects. Finally, we had calculated RMSE(Root Mean Square Error) between the predicted distribution map and prior survey database from other researches to verify the result of this study. The values of RMSE were calculated from 0.1892 to 0.4242 according to each FFG so we could find out a high reliability of this study. The results of this study might be used to develop a new estimation method for aquatic ecosystem with macro invertebrate community and also be used as preliminary data for conservation and restoration of stream habitats.

• The Journal of Korea Assosiation for Disability and Oral Health
• /
• v.15 no.1
• /
• pp.23-28
• /
• 2019

People with intellectual disabilities (ID) usually have poor oral health status and are susceptive to have more caries than general populations. Even when the patients get regular dental treatment, their dental conditions are usually not good for some additional factors. In this presentation, we show dental follow-up care of two patients who have multiple caries. The first case is a 16-year-old boy who has a unilateral facial paralysis with ID. As the lack of controlling of the muscles resulted in interfering with the self-cleansing, it would be associated with a higher incidence on the affected side. Endodontic treatment and caries treatment as restoration was performed. Due to loss of posterior occlusal support on right side, we planned to recover the right posterior relationship by full coverage restorations. In second case, a 20-year-old boy has been on a long-term follow up. Caries treatment, periodontal treatment, and prosthetic treatment were performed under several times of general anesthesia. He has been treated more than 8 years and gets a regular check at 1-month intervals, however, high dental caries susceptibility has been retained. These cases present that dentists should perform more aggressive treatment and be involved in providing better maintenance of patients with intellectual disabilities with multiple caries in adolescence. In other words, it is necessary to suggest a customized preventive strategy for patients with ID.

• Korean Journal of Heritage: History & Science
• /
• v.49 no.1
• /
• pp.120-145
• /
• 2016

An understanding of 'original form' plays an important role as it is the starting point of heritage conservation. This paper delineated several types of understanding on 'original form' over times, and aims at analyzing the way how such concepts has provided a platform of repair works of timber buildings in Korea over times. Conservation in Korea was initiated by the attitude of the Japanese authority during the Colonial period and 'restoring into the earliest form', which had been set in the early stage of the Japanese conservation, has strongly influenced on Korean practice during the period. Such attitude has lasted even after the independence of Korea. In Japan, however, the attitude has shifted to taking a careful decision on the alteration of the existing form during the 1930s. In addition, examination and research in the repair work became essential steps to conduct along with the publication of the report of works. In Korea there has been lack of understanding on the importance of examination and research in repair works and the publication of report of the works has not been mandatory so that it has emphasized on the 'form' in conservation aiming at 'restoring the earliest form'. Such attitude has created the problem of replacing original material during the work which should aim at preserving and maintaining heritage in Korea. Because of these circumstances in preserving the architectural cultural properties in Korea, cultural buildings had succeeded in preserving the outer appearance but there are remaining questions on preserving the original states of them. This paper has pointed out that it is necessary to set out the principles of conserving 'original condition' through further study and discussion based on the careful consideration on both the international principles and Korean context.

• Journal of Cadastre & Land InformatiX
• /
• v.51 no.1
• /
• pp.111-124
• /
• 2021

Recently, Interest in the restoration and 3D reconstruction of cultural properties due to the fire of Notre Dame Cathedral on April 15, 2019 has been focused once again after the 2008 Sungnyemun fire incident in South Korea. In particular, research to restore and reconstruct the actual measurement of cultural properties using LiDAR(Light Detection and ranging) and conventional surveying, which were previously used, using various 3D reconstruction technologies, is being actively conducted. This study acquires data using unmanned aerial imagery of UAV(Unmanned Aerial Vehicle), which has recently established itself as a core technology in the era of the 4th industrial revolution, and the existing CRP(Closed Range Photogrammetry) and terrestrial LiDAR scanning for the Recumbent Buddha of Unju Temple. Then, the 3D reconstruction was performed with three fusion models based on SfM(Structure-from-Motion), and the reproducibility and accuracy of the models were compared and analyzed. In addition, using the best fusion model among the three models, the relationship with the Polar Star(Polaris) was confirmed based on the real world coordinates of the Recumbent Buddha, which contains the astronomical history of Buddhism in the early 11th century Goryeo Dynasty. Through this study, not only the simple external 3D reconstruction of cultural properties, but also the method of reconstructing the historical evidence according to the type and shape of the cultural properties was sought by confirming the historical evidence of the cultural properties in terms of spatial information.

• Journal of Korean Society of Forest Science
• /
• v.109 no.4
• /
• pp.429-437
• /
• 2020

In this study we quantified the long-term change in discharge against precipitation in a forested watershed and investigated how the growth of forest trees influences these changes. We found a proportional relationship between precipitation and discharge for each year, and discharge decreased gradually with time. Precipitation and discharge were highest in July and August, and the changes in precipitation, discharge, and runoff rate did not always coincide, given that high runoff rate was shown in August and September. The monthly coefficient of variation (CV) for discharge was larger than that for precipitation, and the deviation between precipitation and discharge increased gradually. From 2011 to 2017, the gradient of the trend line for the change of total discharge and direct runoff against precipitation decreased, whereas the gradient of the base flow increased in this same time period. A possible explanation is that the water holding capacity of soil deposits increased as the forest soil of the Palgong Mountain watershed developed and the increase of base flow rose with groundwater level together with that of outflow quantity. The coefficient of flood recession was lower in the period 2011 to 2017 than in 2003 to 2010; thus, the reduction of discharge was mitigated and remained steady as time progressed. We conclude from these results that the discharge of surface runoff decreased as tree growth and base flow increased; however, the water yield function of the forest increased gradually.

• The Journal of Korean Philosophical History
• /
• no.56
• /
• pp.239-264
• /
• 2018

Chosun regime, when it replaced the predecessor of Koryo, had to create political ideological system for new integration of the people. The new system, based on Confucianism, replaced religious values of Buddhism with educational ones. In this educational-ideological system, educational objects were mostly limited in character education's. Its goal was 'restoration of good nature'. For the principal agent of educational process, teacher had the initiative. These traits of educational system can be understood as an 'nature-unfolding perspective' or 'formal discipline perspective'. Moreover, the idea of 'teacher shall be served like prince' seems to be ground of political authoritarianism. In this respects, political traits of traditional education system can be restraining elements for developing independent individuality and free citizenship among Korean people. However, traditional teacher was not only authoritarian trainer. As 'a follower of truth and good', he was equal to his disciples. Teacher learned by teaching them. Students could be colleagues of their teacher. And the main traits of traditional education, focusing character development and community consciousness, are still important, in particular, to modern Korean educational and societal environment wanting in humane and participating citizenship.

• Conservation Science in Museum
• /
• v.26
• /
• pp.83-182
• /
• 2021

This study summarized the results of the conservation treatment and investigation on the production method of the golden crown (Treasure No. 339) excavated from Tomb No. 129 (also known as Seobongchong Tomb) in Noseo-dong, Gyeongju-si, Gyeongsangbuk-do Province. The golden crown from Seobongchong Tomb was discovered during the excavations conducted by the Museum of the Government-General of Korea in 1926 during the Japanese colonial era. It is currently in the collection of the National Museum of Korea. A total of six Silla golden crowns have survived in Korea, among which the crown from Seobongchong Tomb is the only example with a dome-shaped hemispherical decoration attached with a bird ornament while otherwise showing the typical features of Silla crowns. The crown had been repaired following its excavation using metallic materials and adhesives, but due to the partial deformation and damage brought about by the repair materials, it required further conservation treatment. This article describes in detail the overall process of the conservation treatment and the restoration of the original form of the golden crown from Seobongchong Tomb, particularly the method of reinforcing the joints to secure the stability of the crown. It presents the characteristics of the crown's production as revealed in the investigation during the conservation treatment, and further analyzes the relationship of this crown from Seobongchong Tomb with other Silla crowns through a comparison of their production techniques. The investigation revealed that the crown was primarily decorated with golden sequins at the time of its production. At a later point some of the sequins in the upright ornament were replaced with comma-shaped jade beads and additional comma-shaped jade beads were added to the headband. In order to determine if such modifications to the decoration had occurred with other Silla crowns, the decoration of the six extant Silla golden crowns were investigated. The crown from Cheonmachong Tomb features traces of this same modification to the decoration and possesses other similarities with the crown from Seobongchong Tomb.