• Restorative Dentistry and Endodontics
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• v.16 no.1
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• pp.133-150
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• 1991

To study the mechanical behavior depended on the restoration method and alveolar bone height at endodontically treated teeth. a finite element model was made which was applied by four types of restoration methods and alveolar bone height on upper central incisor and then 1 Kg force was applied on each model as follows; 1) $45^{\circ}$ diagonal load on incisal edge. 2) $26^{\circ}$ diagonal load on lingual surface. and 3) horizontal load on labial surface. The author analyzed the displacement and stress of teeth and their supporting tissue by finite element method according to three type of loading conditions. The results were as follows : 1. The displacement by restoration method and the stress in dentin was found greater in restoration without a post than in that with a post. 2. The displacement and stress was found about the same when compared : A) in Resin model and PFM model applied by restoration method without a post and B) in PRC model and CPC model applied by restoration method with a post. 3. The lower alveolar bone height was. the greater was the displacement and stress. 4. The lower alveolar bone height was. the greater slightly was the stress of restoration without a post than in that with a post. 5. The stress in loading condition was the greatest in P1 in dentin and post. and was greatest in P3 in alveolar hone. 6. In the restoration method without a post. stress concentration in labial dentin was distributed to a figure of long belt in adjacent part to periodontal ligament. while in restoration method with a post. it was distributed in adjacent part to post side. And in all types of restoration method stress concentration in alveolar bone was distributed along the compact bone of labial and lingual surface.

• Journal of Ecology and Environment
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• v.30 no.3
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• pp.251-255
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• 2007

Self-thinning was measured in Salix communities on Bam Island in Seoul at various age stages. $D^2H$ was used to estimate tree biomass, where D is stem diameter at breast height or 10 cm height for plants with height <1.5 m, and H is height. A log-log plot of density versus $D^2H$ and correlation analysis indicated a significant relationship between density and biomass with equation 'log $D^2H$ = -1.27 log N + 7.06'. This indicates that self-thinning affects biomass in the Salix community with -1.27 as the thinning coefficient. If we assume a thinning exponent -3/2, then the allometric coefficient of the equation, log w = a log $D^2H$ + b, is 1.18. This is much higher than that for any other species studied in Korea. There were statistically significant relationships between age and density and between age and basal area and these relationships suggest guidelines for transplantation of willows and for the assessment of Salix community restoration projects in riverine wetlands based on standard density, basal area, and age. The results of this study may also increase understanding of succession processes in Salix community restoration in riverine wetlands.

• Journal of Environmental Science International
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• v.31 no.5
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• pp.389-404
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• 2022

The purpose of this study is to evaluate the vegetation recovery status of Mudeungsan National Park Jungmeorijae, Jeungsimsa district restoration site, and the Shimwon Valley ecological landscape restoration site in Jirisan National Park. Compared to the control plots, the Jungmeorijae restoration site was analyzed to have height growth of about 73.5%, the average species diversity index of about 75.2%. and the average similarity index was recovered to 7.75%. In the case of the restoration site in Jeungsimsa district, the height growth compared to the control plots was about 69.2%, the average species diversity index was about 55.0%. and the average similarity index was recovered to 25.65%. In the case of the Shimwon Valley ecological landscape restoration area, the height growth compared to the control plots was about 32.6%, the average species diversity index about 176.7%. and the average similarity index was recovered to 0.85%. The restoration site of the Jeungsimsa district was planted with relatively large trees during restoration work, and it took a relatively long time(20 years). Also, the site had less limiting factors due to the low elevation, allowing the degree of vegetation recovery to be higher than that of other sites.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.5
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• pp.70-78
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• 2003

From the viewpoint of the importance of the division theory based on topography(pyungsu) derived from the uniqueness in topography, not to mention of the function of ridge in ruban areas, the destroy of ridges should be prevented from the development of hill areas. This study intends to propose the basic concepts and principles to protect the ridge axis with green in open space and landscape planning. The main results are summarized as follows : First, eco-bridge across the ridges will be connected for the purpose of ecosystem restoration. Second, the protection and restoration of green ridge axis can be completed by Green Structure Plan which has principles and standards such as. - layout of development axis and establishment of rules on preservation - the practical use of various preservation methods and the standards suitable to the methods - laying down the standards of restoration according to the height from ground level - the application of zoning such as height district and urban design for preservation Finally, the design of implementation tools must be needed for protection and restoration.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.1
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• pp.37-51
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• 2015

Sparganium japonicum Rothert. is designated as a near threatened species by the National Institute of Biological Resources and is restrictively distributed in South Korea. To conserve and restore habitats of this plant, we investigated environmental characteristics and vegetation at five habitats during the growing season. Thirty plant species from seventeen families were found in the S. japonicum community. The species frequently found in this community included Utricularia vulgaris, Potamogeton distinctus, Phragmites japonica, Cicuta virosa, Persicaria thunbergii, Phragmites communis, Hydrilla verticillata. Maximum height of this plant reached at August and average height at five habitats is 120 cm at this time. Water and soil environmental factors showed low values compared with that of other wetlands. S. japonicum lived in not only shallow water level but also deep water level. These results can be helpful for S. japonicum habitat conservation and restoration.

• Journal of Korean Neurosurgical Society
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• v.42 no.5
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• pp.371-376
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• 2007

Objective : Balloon kyphoplasty can effectively relieve the symptomatic pain and correct the segmental deformity of osteoporotic vertebral compression fractures. While many articles have reported on the effectiveness of the procedure, there has not been any research on the factors affecting the deformity correction. Here, we evaluated both the relationship between postoperative pain relief and restoration of the vertebral height, and segmental kyphosis, as well as the various factors affecting segmental deformity correction after balloon kyphoplasty. Methods : Between January 2004 and December 2006, 137 patients (158 vertebral levels) underwent balloon kyphoplasty. We analyzed various factors such as the age and sex of the patient, preoperative compression ratio, kyphotic angle of compressed segment, injected PMMA volume, configuration of compression, preoperative bone mineral density (BMD) score, time interval between onset of symptom and the procedure, visual analogue scale (VAS) score for pain rating and surgery-related complications. Results : The mean postoperative VAS score improvement was $4.93{\pm}0.17$. The mean postoperative height restoration rate was $17.8{\pm}1.57%$ and the kyphotic angle reduction was $1.94{\pm}0.38^{\circ}$. However, there were no significant statistical correlations among VAS score improvement, height restoration rate, and kyphotic angle reduction. Among the various factors, the configuration of the compressed vertebral body (p=0.002) was related to the height restoration rate and the direction of the compression (p=0.006) was related with the kyphotic angle reduction. The preoperative compression ratio (p=0.023, p=0.006) and injected PMMA volume (p<0.001, p=0.035) affected both the height restoration and kyphotic angle reduction. Only the preoperative compression ratio was found to be as an independent affecting factor (95% CI : 1.064-5.068). Conclusion : The two major benefits of balloon kyphoplasty are immediate pain relief and local deformity correction, but segmental deformity correction achieved by balloon kyphoplasty does not result in additional pain relief. Among the factors that were shown to affect the segmental deformity correction, configuration of the compressed vertebral body, direction of the most compressed area, and preoperative compression ratio were not modifiable. However, careful preoperative consideration about the modifiable factor, the PMMA volume to inject, may contribute to the dynamic correction of the segmental deformity.

• Korean Journal of Environment and Ecology
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• v.33 no.4
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• pp.453-461
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• 2019

This study was conducted to monitor the soil characteristics and growth of Pinus densiflora and to determine the effect of soil characteristics on growth rate five years after an ecological restoration project in Baekdudaegan ridge including Ihwaryeong, Yuksimnyeong, and Beoljae sites. The ecological restoration project was executed with the forest of P. densiflora in 2012-2013. In April 2018, we collected soil samples from each site and measured the height and the diameter at breach height (DBH) of P. densiflora. Although there was no significant change of soil pH compared to the early stage of restoration (one year after the project), it was high in Ihwaryeong, and Beoljae with values of 7.7 and 6.4, respectively. Also, the organic matter decreased by 70-80%, and the available phosphorus (P) was unchanged in three restoration sites. The decreased organic matter can be attributed to restriction of inflow and thus decomposition of litter in the early stage after the restoration. The tree height growth rate ($m\;yr^{-1}$) of P. densiflora in Yuksimnyeong was the highest at 1.02, followed by Beolja at 0.75 and Ihwaryeong at 0.17. The height growth rate showed negative relationships with soil pH and cations, including Na and Ca concentrations and a positive relationship with available phosphate. The low growth rate in the Ihwaryeong site, in particular, might result from the poor nutrient availability due to high soil pH and the decrease in water absorption into the root due to high Na and Ca concentrations. The substantial reduction of organic matter after five years indicates that the need for soil improvement using chemical fertilizer and biochar.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.6
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• pp.76-85
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• 2009

This study was carried to select the proper vegetation base materials which improve soil quality in abandoned coal mine areas. Also, we aimed at the feasibility of the direct seeding method without soil molding for the ecological restoration in those areas. We set total eight plots within the study site established on an abandoned coal mine area near Taebaek city, Gangwon province in April 2006. The plots were classified as two groups(straw mats mulching and no mulching), and the four treatments (C; control, MI; microbial innoculation, WC; wood chip, OF; organic fertilizer) were applied in each two groups for the soil conditioning. The survival of Pinus densiflora was highest among other species(Betula platyphylla var. japonica, Amorpha fruticosa and Arundinella hirta). For the non straw mat, the survival rate of Pinus densiflora seedlings was highest in the WC treatment($1,756trees/m^2$). For the straw mat, survival rate of Pinus densiflora seedlings was also highest in the WC treatment ($1,622trees/m^2$). In addition, for the non straw mat, the height growth of Pinus densiflora seedling was highest in the OF treatment($12.4{\pm}3.9cm$). For the straw mat, the height growth of Pinus densiflora seedling was also highest in the OF treatment($18.7{\pm}5.3cm$). In general, organic fertilizer treatment with the straw mat was most effective for seedling growth. Also, we suggested that the direct seeding method without soil molding could be sufficiently possible for revegetating abandoned coal mine, Korea.

• Journal of Environmental Science International
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• v.32 no.3
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• pp.161-171
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• 2023

The present study evaluated growth factors affecting oak community plantations through literature review and a field survey. Specifically, 41 related literature sources were analyzed and field surveys were conducted to collect growth data. Previous studies were analyzed to identify variables with high frequency of use. The frequency of use was in the order of tree size > environment > planting density > forest age. Analysis of factors impacting height and diameter growth revealed that the growth rate of species other than Quercus variabilis was negative in the field survey. This may be because of differences between the actual trees planted and specifications in the construction drawings, which may be attributed to the site conditions and decisions made by the project subject during construction. Furthermore, simple linear regression analysis was conducted with time, height at planting, density, and species code as the independent variables and growth rate as the dependent variable. A strong positive linear correlation was noted between height and diameter. This work builds a foundation for developing a forest restoration model and simulation program based on a regression model derived from the four variables tested.

• Journal of Korean Neurosurgical Society
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• v.52 no.4
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• pp.339-345
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• 2012

Objective : The purpose of this study was to investigate the patterns and the risk factors of newly developed vertebral compression fractures (VCFs) after percutaneous vertebroplasty (PVP). Methods : We performed a retrospective review of the 244 patients treated with PVP from September 2006 to February 2011. Among these patients, we selected 49 patients with newly developed VCFs following PVP as the new VCFs group, and the remaining 195 patients as the no VCFs group. The new VCFs group was further divided into 2 groups : an adjacent fractures group and a nonadjacent fractures group. The following data were collected from the groups : age, gender, body weight/height, body mass index (BMI), bone mineral density (BMD) score of the spine and femur, level of initial fracture, restoration rate of anterior/middle vertebral height, and intradiscal cement leakage, volume of polymethylmethacrylate (PMMA). Results : Age, gender, mean body height/weight, mean BMI and volume of PMMA of each of the group are not statistically significantly associated with fractures. In comparison between the new VCFs group and the no VCFs group, lower BMD, intradiscal cement leakage and anterior vertebral height restoration were the significant predictive factors of the fracture. In addition, new VCFs occurrence at the adjacent spines was statistically significant, when the initial fracture levels were confined to the thoracolumbar junction, among the subgroups of new VCFs. Conclusion : Lower spinal BMD, the greater anterior vertebral height restoration rate and intradiscal cement leakage were confirmed as risk factors for newly formed VCFs after PVP.