• The Journal of Advanced Prosthodontics
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• 제12권4호
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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%).

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1993년도 추계학술대회 논문집
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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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• 제30권1호
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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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• 제18권1호
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• pp.45-52
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• 2001

본 논문은 솔잎혹파리 피해임지에서 수목의 외형적인자(수고, 수관폭, 흉고직경, 지하고)와 shigometer를 이용한 전기 저항치 ($k{\Omega}$)의 관계를 조사하였다. 외형적인자와 저항치간의 관계는 수고, 수관폭, 흉고직경은 높은 상관관계가 있었고, 지하고는 뚜렷한 관계가 나타나지 않았다. 수고, 수관폭, 흉고직경은 큰 수목이 전기저항치가 낮았고(수목의 활력이 높음) 작은 수목이 전기저항치가 높았다(수목의 활력이 낮음). 솔잎혹파리 피해임지의 고사목과 생존목을 비교하면 고사목이 생존목에 비하여 수관폭과 흉고직경의 크기는 작았고, 지하고는 높았다. 전기저항치를 3등급으로 구분 한 결과(< $14{\Omega}$, 생존가능성 양호, $14{\sim}20{\Omega}$, > $20k{\Omega}$고사 가능성 있음), 외형적인자의 크기는 낮은등급(< $14{\Omega}$)에서 수고, 수관폭, 흉고직경이 컸으며, 지하고는 낮았다. 조사한 외형적인자와 수세와의 관계를 직선회귀 방정식으로 산출한 결과 Y=-0.572${\times}$수고-1.163${\times}$수관폭-0.242${\times}$흉고직경+0.757${\times}$지하고+25.765이였으며 이들의 회귀식은 5%의 수준에서 유의성이 인정된다.

• 한국환경생태학회지
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• 제33권5호
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• pp.587-595
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• 2019

도심 산지형 공원 내 식생유형별 요인이 공기이온에 미치는 영향력을 파악하고자 충주시 탄금대 공원을 대상으로 수행하였다. 측정지점은 능선부 내 수종, 흉고직경, 울폐도, 층위구조에 따라 설정하였으며, 기상요소와 공기이온을 측정하였다. 공기이온 측정결과, 양이온 발생량은 평균 $610.90{\pm}50.27ea/cm^3$, 음이온 발생량은 평균 $723.58{\pm}64.25ea/cm^3$, 이온지수는 $1.19{\pm}0.10$이였다. 식생유형에 따른 분석결과는 다음과 같다. 첫째, 공기이온은 수종, 흉고직경, 층위구조에 따라 차이가 발생하였으며, 통계적으로 유의한 것으로 분석되었다. 둘째, 이온지수와 식생유형과의 관계에서 수종, 흉고직경, 울폐도, 층위구조 모두에서 정의 상관관계로 분석되었으며, 양이온의 경우 수종, 흉고직경, 울폐도와 부의 상관관계, 음이온의 경우 수종, 흉고직경, 울폐도, 층위구조에서 정의 상관관계로 분석되었다. 셋째, 능선부 내 이온지수의 영향요인은 기상요인과 식생유형을 비교한 결과 식생유형의 상관계수가 더 높았으며, 세부적으로는 수종 > 층위구조 > 울폐도 > 흉고직경의 순이었다. 본 연구에서는 능선부를 대상으로 공기이온을 평가한 한계점이 존재한다. 이에 향후 공기이온에 대한 연구에서 지형구조, 식생유형을 모두 고려한 분석이 이루어져야할 것이며, 계절에 따른 변화 비교연구가 필요할 것으로 판단되었다.

• The Korean Journal of Ecology
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• 제8권4호
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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.

• 한국산림과학회지
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• 제96권2호
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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.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 제7회 압연 심포지엄
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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.

• 대한치과의사협회지
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• 제47권12호
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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.

• 한국정밀공학회지
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• 제19권11호
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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.