• Journal of Periodontal and Implant Science
• /
• 제36권2호
• /
• pp.345-359
• /
• 2006

Loss of maxillary molar teeth leads to rapid loss of crestal bone and inferior expansion of the maxillary sinus floor (secondary pneumatization). Rehabilitation of the site with osseointegrated dental implants often represents a clinical challenge because of the insufficient bone volume resulted from this phenomenon. Boyne & James proposed the classic procedure for maxillary sinus floor elevation entails preparation of a trap door including the Schneiderian membrane in the lateral sinus wall. Summers proposed another non-invasive method using a set of osteotome and the osteotome sinus floor elevation (OSFE) was proposed for implant sites with at least 5-6mm of bone between the alveolar crest and the maxillary sinus floor. The change of grafted material in maxillary sinus is important for implant survival and the evaluation of graft height after maxillary sinus floor elevation is composed of histologic evaluation and radiomorphometric evaluation. The aim of the present study was radiographically evaluate the graft height change after maxillary sinus floor elevation and the influence of the graft material type in height change and the bone remodeling of grafts in sinus. A total of 59 patients (28 in lateral approach and 31 in crestal approach) who underwent maxillary sinus floor elevation composed of lateral approach and crestal approach were radiographically followed for up to about 48 months. Change in sinusgraft height were calculated with respect to implant length (IL) and grafted sinus height(BL). It was evaluated the change of the graft height according to time, the influence of the approach technique (staged approach and simultaneous approach) in lateral approach to change of the graft height, and the influence of the type of graft materials to change of the graft height. Patients were divided into three class based on the height of the grafted sinus floor relative to the implant apex and evaluated the proportion change of that class (Class I, in which the grafted sinus floor was above the implant apex; Class II, in which the implant apex was level with the grafted sinus floor; and Class III, in which the grafted sinus floor was below the implant apex). And it was evaluated th bone remodeling in sinus during 12 months using SGRl(by $Br\ddot{a}gger$ et al). The result was like that; Sinus graft height decreased significantly in both lateral approach and crestal approach in first 12 months (p$MBCP^{TM}$ had minimum height loss. Class III and Class II was increased by time in both lateral and crestal approach and Class I was decreased by time. SGRI was increased statistically significantly from baseline to 3 months and 3 months(p<0.05) to 12 months(p$ICB^{(R)}$ single use, more reduction of sinusgraft height was appeared. Therefore we speculated that the mixture of graft materials is preferable as a reduction of graft materials. Increasing of the SGRI as time goes by explains the stability of implant, but additional histologic or computed tomographic study will be needed for accurate conclusion. From the radiographic evaluation, we come to know that placement of dental implant with sinus floor elevation is an effective procedure in atrophic maxillary reconstruction.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2003년도 사면안정학술발표회
• /
• pp.103-116
• /
• 2003

Rockfall Protection fence is one of the most common rockfall Protection methods in Korea. If rockfall protection fences are required along the road or railway, their location, height and capacity, in terms of the maximum kinetic energy that they can absorb, should be specified. Within this paper, the best practice of rockfall barrier is introduced. Modern rockfall simulations as a means to define risks, protection requirements, dynamic loading and height of potential structures and selection of appropriate placement is presented. Technical possibilities of rockfall barriers and their actual limits are presented. Safety concepts based on probabilistic approaches are proposed. Recent studies peformed in other countries show that Flexible Barriers are also a feasible system to stop and retain debris flows. Finally an outlook onto further development is given.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2014년도 추계 학술논문 발표대회
• /
• pp.205-206
• /
• 2014

It is very important to reduce the construction duration of the Reactor Containment Building (RCB) when considering the more than 50 months on average from concrete placement to completion. The purpose of this study attempts to evaluate the single-stage workability of the system given a change in the height of the setting of RCB exterior wall formwork to be used in nuclear power plant construction. As a result of this study, it is possible height of 3.5m~4m uses formwork when analyzing the construction period and material costs an increase in formwork by concrete lateral pressure, to ensure the workability of the RCB exterior wall formwork. Through this study, I want to provide as basic data for the improvement of workability and RCB shortening the construction period.

• 국제초고층학회논문집
• /
• 제7권2호
• /
• pp.141-143
• /
• 2018

Critics of height argue that it de-humanizes our cities. Yet a critical mass is a necessity for vibrant city life, and height is a key contributor. If we can overcome the environmental impacts and technicalities of building tall and dense, our cities' streets can thrive and prosper. To make this happen, we must move towards working together to share resources, so we can ensure the continuity of the public realm. We already have the tools to do this; the challenge lies in the coordination of the public and private institutions that govern urban space. District heating and cooling systems; shared logistics spaces; care, responsibility and ownership of the public realm between buildings; seamless connectivity between modes of transport; creative combinations of shelter and seating, and the placement of buildings so that they are not overbearing to the streets around them - these attributes can be found in many places, though rarely all at once. This paper looks at the development of the city and offers Barangaroo South, Sydney, which addresses all these aspects, as a potential template for future city planning.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2003년도 춘계학술대회 논문집
• /
• pp.68-81
• /
• 2003

Rockfall protection fence is one of the most common rockfall protection methods in Korea. If rockfall protection fences are required along the road or railway, their location, height and capacity, in terms of the maximum kinetic energy that they can absorb, should be specified. Within this paper, the best practice of rockfall barrier is introduced. Modern rockfall simulations as a means to define risks, protection requirements, dynamic loading and height of potential structures and selection of appropriate placement is presented. Technical possibilities of rockfall barriers and their actual limits are presented. Safety concepts based on probabilities approaches are proposed. Recent studies performed in other countries show that Flexible Barriers are also a feasible system to stop and retain debris flows. Finally an outlook onto further development is given.

• Journal of Periodontal and Implant Science
• /
• 제44권2호
• /
• pp.50-56
• /
• 2014

Purpose: The aims of this study were to measure the distance of the intraosseous vascular anastomosis in the anterolateral wall of the maxillary sinus from different reference points, and to correlate the location of the intraosseous vascular anastomosis with the tooth position and the residual bone height of the maxilla. Methods: Computed tomography (CT) images were taken from 283 patients undergoing dental implants placement in the posterior maxilla. Three horizontal lines were drawn at the ridge crest, maxillary sinus floor, and the position of the anastomosis. A vertical second line at the center of each tooth was drawn perpendicular to the horizontal lines. The distance from the ridge crest to the maxillary sinus floor and the distance from the maxillary sinus floor to the bony canal were measured from the intersections of the horizontal and vertical lines. The residual alveolar bone height was used to categorize three groups: group 1,<4 mm; group 2, between 4 and 8 mm; and group 3, >8 mm. Results: The residual bone height values of different tooth positions were significantly different (P=0.0002). The distance from the maxillary sinus floor to the intraosseous vascular anastomosis was significantly different between groups 1 and 3 (P=0.0039). At the molar sites, a moderate negative correlation was found between the residual bone height and the distance from the maxillary sinus floor to the intraosseous anastomosis. The distances of the alveolar ridge crest and the maxillary sinus from the intraosseous vascular anastomosis were not significantly different between sexes. Conclusions: Within the limitations of this study, sites with a higher residual bone height in the molar regions were at a relatively high risk of artery damage during window osteotomy preparation; therefore, we recommend taking more precautions when using a lateral approach for sinus elevation.

• Imaging Science in Dentistry
• /
• 제51권3호
• /
• pp.243-250
• /
• 2021

Purpose: The objective of this study was to evaluate the amount of height available for a maxillary sinus augmentation procedure without blocking the ostium and jeopardizing the drainage of the ostiomeatal complex using cone-beam computed tomography (CBCT) imaging. Materials and Methods: A total of 200 sinonasal complexes comprising 100 dentate and 100 edentulous scans were retrospectively assessed using CBCT. Invivo 5.0, a CBCT reconstruction program, was used for image evaluation. The coronal section demonstrating the ostiomeatal complex was selected as a reference view to perform measurements of the sinus. The measurements were done by 2 evaluators in separate sessions. Comparative analyses of measurements were performed between dentate and edentulous patients and between male and female patients. Results: The safe height to which the sinus can be elevated without compromising the integrity of the ostiomeatal complex was calculated for each sinus. In the presence of significant mucosal thickening, the height available for augmentation was calculated by subtracting the height of mucosal thickening from the sinus floor to the location of the ostium. In this study, the available height was approximately 27.05 mm for dentate and 23.40 mm for edentulous patients. The inter-operator reliability was excellent for all the parameters evaluated. Conclusion: This retrospective study with a limited number of patients from a single university-based site shows that CBCT is valuable in evaluating the location and patency of the ostium for planning sinus augmentation procedures for dental implant placement.

• 디지털콘텐츠학회 논문지
• /
• 제19권4호
• /
• pp.815-819
• /
• 2018

본 논문에서는 Foot Placement Estimator (FPE)를 사용하여 point foot을 갖는 이족 로봇의 3차원 시뮬레이션을 진행하고 이족로봇의 균형유지를 연구하였다. FPE 방법은 에너지 보존에 근거한 제어 방법으로서 보행 중인 로봇의 모든 에너지가 위치 에너지로 변환되는 지점에 로봇이 발을 디뎌 몸체가 넘어지지 않고 균형을 유지하며 이동하도록 하는 제어방법이다. 본 연구에서는 로봇이 이동하지는 않고 제자리에서 균형을 유지하며 서 있는 시뮬레이션을 진행하였다. 이를 위해 point foot을 갖는 6자유도 이족 로봇을 모델링하였으며 바닥과의 접촉 및 마찰 환경을 구현하였다. 로봇의 무게는 1kg이며 지면과 무게 중심점과의 거리는 1m로, 무게중심점은 로봇 몸체의 정 중앙에 위치하도록 설계하였다. 다음으로 로봇 몸체의 각속도와 직선속도 그리고 무게 중심점의 높이로 부터 FPE 지점을 계산하고 로봇이 해당 지점을 디뎌 균형을 유지하게 끔 하였다. 몸체의 초기 각도를 $5^{\circ}$, $-5^{\circ}$로 변화시키며 시뮬레이션 한 결과, 모든 초기 조건에서 로봇이 쓰러지지 않고 자세의 균형을 유지하며 서 있는 것을 확인할 수 있었다.

• Journal of Periodontal and Implant Science
• /
• 제42권1호
• /
• pp.20-24
• /
• 2012

Purpose: The purpose of this study was to evaluate the soft tissue and bone change around two adjacent implants in onestage implant surgery. Methods: Eleven subjects (7 males, 4 females) who were needed placement of 2 adjacent implants in the molar area were included. The two implants were placed with the platform at the level of the alveolar crest. The interproximal bone between the 2 implants was not covered with gingiva. After surgery, an alginate impression was taken to record the gingival shape and radiographs were taken to evaluate implant placement. Using a master cast, the gingival height was measured at baseline, 4 weeks, and 12 weeks. In the radiograph, the alveolar bone level was measured at the mesial and distal side of both implants at baseline and 12 weeks. Results: The exposed bone was covered with gingiva at both 4 and 12 weeks. Loss of alveolar bone around implants was found in all areas. The alveolar bone level in the exposed bone area did not differ from that in the non-exposed area. Conclusions: This study showed that the alveolar bone level and gingival height around 2 adjacent implants in the exposed bone area did not differ from that in unexposed bone area.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제38권2호
• /
• pp.85-89
• /
• 2012

Objectives: This study was to evaluate the effect of vertical bone gain and success rate and analyze the failure cases using the hydrodynamic piezoelectric internal sinus elevation (HPISE) technique. Materials and Methods: Patients who had been operated in the three centers including Daegu Catholic University Medical Center were selected for this study. The mucoperiosteal flap was elevated, and the sinus floor was then broken by specially designed piezoelectric insert, with hydraulic pressure applied to the sinus membrane for even elevation. Afterward, implants were placed. Panoramic radiogram or computed tomogram was taken before and after surgery and at the second operation and prosthesis placement. Later, changes in vertical height were measured and compared. The survival rate was based on the criteria of Buser et al. and Cochran et al. Results: In this study, 8 implants failed out of a total of 169 implants, resulting a success rate of 95.3%. These failure cases were due to insufficient initial stability or sinus membrane perforation. The mean of radiographic vertical height change at prosthesis placement was 5.7 mm (0.5-10.5 mm). Conclusion: In this study, HPISE technique was found to be a predictable treatment for atrophic maxilla and an alternative technique to the lateral approach.