• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.239-249
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• 2020

PURPOSE. The purpose of this study was to investigate survival rates of the implants used in implant assisted removable partial dentures (IARPDs). MATERIALS AND METHODS. The study was conducted on 21 patients who were treated with IARPDs. The mean follow-up period for IARPD patients ranged from 12 to 185 months (mean 47.9 months). A total of 58 implants were used for IARPDs in two different modalities: 41 for surveyed crowns and 17 for overdentures. The survival of implants was determined by clinical and radiographic evaluations considering relevant factors: location, RPD classification, opposing dentition, splinting, and implant diameter. RESULTS. The survival rate of total 58 implants was 93.1%: 95.1% for implants supporting surveyed crowns and 88.2% for implants used in overdentures. Considering only the implants supporting surveyed crown, regular diameter implants showed a higher survival rate than narrow or wide diameter implants. CONCLUSION. The survival rate of the implants used in IARPDs was 93.1% (surveyed crown: 95.1%, overdenture: 88.2%).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.499-504
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• 1993

To find a way for establishing work roll initial crown according to roll conditions, computer simulation for predicting plate crown in plate mill is done and effects of roll conditions on plate crown is analysed. Roll gap profile and plate crown are measured to be compared to the calculated values. As a result,a regression equation to establish work roll initial crown according to roll cooditions such as backup roll diameter, backup roll crown and work roll crown is obtained.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.30 no.1
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• pp.60-71
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• 2008

The objective of this study is to evaluate the stress distribution according to the thread design and the marginal bone loss of a single unit dental implant under the axial and offset-axial loading by three dimensional finite element analysis. The implants used had the diameter of 5mm and 4mm with 13mm in length and prosthesis with a conical type which is 6mm in height and 12mm in diameter. The thread designs were triangular, square and buttress. In the three dimensional finite element model with $15\times15\times20mm$ hexahedron and 2mm cortical thickness, implants were placed with crown to root ratio 7:12, 10:9, 13:6 and 16:3. And additionally the axial force of 100N were applied into 0mm, 2mm and 4mm away from the center of the implants. The results were as follows 1. The maximum von-Mises stress in cortical bone was concentrated to cervical area of implant, and in cancellous bone, apical portion. 2. Comparing the von-Mises stresses in cortical bone of 2mm and 4mm offset loading with central axial loading, it were increased to 3 and 5 times in diameter 4mm implant, and 2 and 4 times, in diameter 5mm implant. 3. The square threads were more effective than the triangular and butress as the longer diameter, the offset loading, and the worse crown to root ratio. 4. The von-Mises stresses were relatively stable until crown to root ratio 13:6, but it was suddenly increased at 16:3. From the results of this study, minimum requirement of crown to root ratio of implant is 2:1, and in the respect of crown to root ratio, diameter and offset loading, square threads are more effective than triangular and buttress threads.

• Journal of Forest and Environmental Science
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• v.18 no.1
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• pp.45-52
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• 2001

This paper investigated external factors (height. crown width. diameter breath height, clear length) of tree and electric resistance ($k{\Omega}$) in damaged forest by Thecodiplosis japonensis Uchida et Inouye. The height. crown width and diameter breath height of tree external factors have high a coefficient of correlation. but clear length has not a coefficient of correlation. In relationship of electric resistance and external factor. big tree that height. crown width. diameter breath height has lower electric resistance value than that of small tree. (low electric resistance value is high tree vigor, high electric resistance value is low tree vigor)) Dead tree have smaller diameter breath height. crown width. higher clear length than survival tree in damaged forest by Thecodiplosis japonensis Uchida et Inouye. To investigation of relationship external factors according to electric resistance value. electric resistance value was divided three class (< $l4k{\Omega}$, possible of survival. $14{\sim}20k{\Omega}$, > $20k{\Omega}$, possible of dead). In lower class(< $l4k{\Omega}$), external factors have bigger which was height. crown width. diameter breath height and lower which was clear length than them of higher class ($14{\sim}20k{\Omega}$, > $20k{\Omega}$). Linear regression solutions of electric resistance and external factors were Y = -0.572 ${\times}$ Height - 1.163 ${\times}$ crown width - 0.242 ${\times}$ diameter breath height + 0.757 ${\times}$ clear length + 25.765. Regression solutions were significant in 5%.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.587-595
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• 2019

This study analyzed the influence of the environmental factor of each vegetation type in an urban, mountainous park (Tangeumdae Park in Chungju) on air ion. The measuring points were divided according to the tree species, diameter at breast height, crown density, and layered structure, and the meteorological factors and the air ion were measured. The results of the measurement showed the average generation of positive ions of $610.90{\pm}50.27ea/cm^3$, the average generation of negative ions of $723.58{\pm}64.25ea/cm^3$, and the air ion index of $1.19{\pm}0.10$. The results of the analysis, according to the vegetation type, are as follows. Firstly, the air ion varied according to the species, the chest diameter at breast height, and the layered structure, and was analyzed to be statistically significant. Secondly, the air ion and the vegetation type showed a positive correlation with the species, diameter at breast height, crown density, and layered structure. The cation showed a negative correlation with the species, diameter at breast height, and the crown density, and the anion showed a positive correlation with the species, the diameter at breast height, crown density, and layered structure. Thirdly, the ion index in ridges had a higher correlation with the vegetation type than the meteorological factors. In detail, the correlation was higher in the species > layered structure > crown density > diameter at breast height. This study had the limitation of evaluating air ions in the ridge. Therefore, future studies on air ion should consider both terrain structure and vegetation type and analyze the seasonal changes and comparison.

• The Korean Journal of Ecology
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• v.8 no.4
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• pp.197-200
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• 1985

The relations of crown width and DBH for Pinus densiflora, Pinus rigida, Pinus koraiensis, and Ginkgo biloba were accomplished to estimate the level of crown competition. Measurements of the relations revealed that crown width and DBH were highly correlated for the same species. Also it seems that these relations are independent of age and site quality. The results of regression analysis were as follow: P. densiflora, Y=0.3477X+0.3828 r=0.95 p. rigida, Y=0.3537X+0.1645 r=0.95 P. koraiensis, Y=0.2895X+0.6310 r=0.92 G. biloba, Y=0.4360X+0.0995 r=0.90 The significant differences between G. biloba and pine species seems due to their structural differences of crown formation according to tree species. As results of computing Maximum Crown Area and Crown Competition Factor as indices of crown competition, they indicated that P. densiflora would grow better under the natural conditions.

• Journal of Korean Society of Forest Science
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• v.96 no.2
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• pp.189-196
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• 2007

Allometry, basal area equations, and volume equations were developed with various tree measurement variables for the major species, Quercus mongolica and Quercus variabilis, in Korean natural hardwood forests. For allometry models, the relationships between total height-DBH, crown width-DBH, height to the widest portion of the crown-total height, and height to base of crown-total height were investigated. Multiple regression methods were used to relate annual basal area growth to tree variables of initial size (DBH, total height, crown width) and relative size (relative diameter, relative height) as well as competition measures (competition index, crown class, exposed crown area, percent exposed crown area, live crown ratio). For tree volume equations, the combined-variable and Schumacher models were fitted with DBH, total height and crown width for both species.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.04a
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• pp.13-16
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• 2009

In order to investigate the effects of geometry factors such as a roil diameter ratio and backup roll crown of the stress concentration factor on the edge of backup roil end, 3-dimensional FEM analyses of stress at the contact of backup roll and work roll assembled in a 4-high strip mill were carried out, It was made clear that the peak stress at the edge is about 2 to 3 times of that at the longitudinal center of the roll barrel and the peak stress proportionally increase with decreasing the ratio of backup roll diameter to work roll diameter Furthermore a crowning on the backup roll is effective to decrease the maximum edge stress.

• The Journal of the Korean dental association
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• v.47 no.12
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• pp.823-829
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• 2009

Purpose : The aim of this study was to evaluate the survival rate of sintered porous-surfaced implants placed in the edentulous posterior mandibles, in relation to implant length and diameter, crown-to-implant ratio, and types of prostheses, for a maximum of eight years of functioning. Material and Methods : The study group consisted of 43 partially edentulous patients who visited Catholic University Hospital of Daegu and one private dental clinic. A total of 122 sintered porous-surfaced implants n $Endopore^{(R)}$ (Inn ova Life Sciences, Toronto, Ontario, Canada) -- were placed in the edentulous posterior mandibles, Two diameter sizes (4.1 mm and 5.0 mm) and four lengths (5.0 mm, 7.0 mm, 9.0 mm, and 12.0 mm) were used. One hundred and three implants were splinted and 21 implants were nonsplinted. The survival rates of the implants in relation to length, diameter, crown-to-implant ratio, and types of prostheses were investigated. Statistical data were analyzed using SPSS Win.Ver 14.0 software with the Chi-square test. Results : The survival rate of the 4.1mm diameter implants was 100% and 91.2% for the 5.0mm diameter implants. The survival rates of the implants of differing diameters were found to be statistically different (p=0.005). The survival rates of both the 5.0mm and 7.0 mm length implants were 100%. The survival rate of the 9.0mm length implants was 97.9% and for the 12.0mm length implants was 95.1%. There was no statistical difference in survival rates for the differing lengths of implants. Of the 103 prostheses that were splinted, the survival rate was 98.0%. The survival rate of splinted prostheses was higher than that of the non-splinted prostheses, but was found to be not statistically different. There were no failed cases when the crown-to-implant ratio was under 1.0. When the crown-to-implant ratio was between 1.0 and 1.5, the failure rate of the implants was 6.7%. No failure was recorded with the ratio range of 1.5 to 2.0. Relative to the crown-to-implant ratio of 1.0, the failure rates were statistically different (p=0.048). Discussion and Conclusion : The cumulative survival rate of the porous-surfaced implants placed in the edentulous posterior mandibles was 97.5%. Short porous-surfaced implants showed satisfactory results after a maximum of nine years of functioning in the edentulous posterior mandibles.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.11
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• pp.200-210
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• 2002

In twin roll strip casting process, coupled analyses of heat transfer and deformation for the cast roll are carried out by using the finite element program MARC to examine the thermal crown. Shrink fit effect and plastic deformation are considered. The results shows that the thermal crown is greatly influenced by shrink ft and that the thermal crown for POSCO Pilot Caster 2 Copper Roll has “M” shape. The effects of several factors on thermal crown are also investigated. The amount of thermal crown increases as heat flux, casting speed, steeve thickness and casting roll width increase and decreases as the casting roll diameter increases.