(A) finite element stress analysis of the stress distribution and the shock absorption in an osseointegrated implant-natural tooth supported fi

치의학과/박사[한글] 골유착성 임프란트와 자연치를 이용한 고정성 국소의치에서 정하중 및 동하중으로 인하여 지지 골조직에 발생하는 응력을 보다 효율적으로 분산, 완화시킬 수 있는 방법을 비교 연구하고자 이차원 유한요소법적 응력분석을 이용하여, 첫째, 정하중시 보철물 고정나사의 설계 유무 및 보철물 고정나사의 물리적 성질의 변화, 상부 보철물의 물리적 성질의 변화, 그리고 내가동연결장치(intramobile connector)의 사용등에 따른 응력분산 효과를 상호 비교 분석하고, 둘째, 동하중시 내가동연결장치 및 상부 보철물 교합면의 복합레진 피개에 따른 충격흡수 효과를 비교 분석한 결과 다음과 같은 결론을 얻었다. 1. 정하중시 보철물 고정나사의 사용 및 보철물 고정나사의 굴성증가, 또는 상부 보철물의 굴성증가로 인하여 임프란트 경부 피질골에 응력이 국소적으로 증가되었으며, 자연치 주위 지지골에서는 뚜렷한 응력변화가 관찰되지 않았다. 2. 정하중시 내가동연결장치의 사용으로 임프란트 경부 피질골에 집중되는 응력이 크게 감소되었으며, 자연치 주위 지지골에 약간의 응력이 증가되었다. 3. 동하중시 교합면의 복합레진 피개 또는 내가동연결장치의 사용으로 임프란트 주위 지지골에 발생하는 응력이 감소되었으며, 복합레진 피개가 내가동연결장치 보다 충격흡수 효과가 큰 것으로 나타났다. A FINITE ELEMENT STRESS ANALYSIS OF THE STRESS DISTRIBUTI0N AND THE SHOCK ABSORPTION IN AN OSSEOINTEGRATED IMPLANT-NATURAL TOOTH SUPPORTED FIXED PARTIAL DENTURE Chang Mo Jeoung D.D.S., M.S.D. Department of Dental Science, Graduate School, Yonsei University (Directed by Ho Yong Lee, D.D.S., M.S.D., Ph.D.) The long-term success of any dental implant is dependent upon the optimization of stresses which occur during oral function and parafunction. Especially, it has been suggested that there is an unique set of problems associated with joining an osseointegrated implant and a natural tooth with a fixed partial denture. For this particular case, although many literatures suggest different ways to avoid high stress concentrations on the bone surrounding the implant under static and dynamic loading cunditions, but few studies on the biomechanical efficacy of each assertion have been reported. The purpose of this investigation was to evaluate the efficacies of clinically suggested methods on stress distribution under static load and shock absorption under dynamic load, using two dimensional finite element method. In FEM models of osseointegrated implant-natural tooth supported fixed partial dentures, calculations were made on the stresses in surrounding bone and on the deflections of abutments and superstructure, first, to compare the difference in stress distribution effects under static load by the flexure of fastening screw or prosthesis, or intramobile connector, and second, to compare the difference in the shock absorption effects under dynamic load by intamobile connector or occlusal veneering with composite resin. The results of this analysis suggest that: 1. Under static load condition, using an implant design with fastenign screw connecting implant abutment and prosthesis or increasing the flexibility of fastening screw, or increasing the flexibility of prosthesis led to the increase in height of peak stresses in cortical bone surrounding the implant, and has little effect on stress change in bone around the natural tooth. 2. Under static load condition, intramobile connector caused the substantial decrease in stress concentration in cortical bone surrounding the implant and the slight increase in stress in bone around the natural tooth. 3. Under dynamic load condition, both intramobile connector and composite resin veneering showed shock absorption effect on bone surrounding the implant and composite resin veneering had a greater shock absorption effect than intramobile connector. [영문] The long-term success of any dental implant is dependent upon the optimization of stresses which occur during oral function and parafunction. Especially, it has been suggested that there is an unique set of problems associated with joining an osseointegrated implant and a natural tooth with a fixed partial denture. For this particular case, although many literatures suggest different ways to avoid high stress concentrations on the bone surrounding the implant under static and dynamic loading cunditions, but few studies on the biomechanical efficacy of each assertion have been reported. The purpose of this investigation was to evaluate the efficacies of clinically suggested methods on stress distribution under static load and shock absorption under dynamic load, using two dimensional finite element method. In FEM models of osseointegrated implant-natural tooth supported fixed partial dentures, calculations were made on the stresses in surrounding bone and on the deflections of abutments and superstructure, first, to compare the difference in stress distribution effects under static load by the flexure of fastening screw or prosthesis, or intramobile connector, and second, to compare the difference in the shock absorption effects under dynamic load by intamobile connector or occlusal veneering with composite resin. The results of this analysis suggest that: 1. Under static load condition, using an implant design with fastenign screw connecting implant abutment and prosthesis or increasing the flexibility of fastening screw, or increasing the flexibility of prosthesis led to the increase in height of peak stresses in cortical bone surrounding the implant, and has little effect on stress change in bone around the natural tooth. 2. Under static load condition, intramobile connector caused the substantial decrease in stress concentration in cortical bone surrounding the implant and the slight increase in stress in bone around the natural tooth. 3. Under dynamic load condition, both intramobile connector and composite resin veneering showed shock absorption effect on bone surrounding the implant and composite resin veneering had a greater shock absorption effect than intramobile connector.restrictio

A Kinetic Study for Selective Catalytic Reduction of NO by NH3

Maste

Hydrogel 내부의 상호 연결된 3차원 Micro-channels 제작 연구

Maste

온라인 브랜드 커뮤니티 충성도가 브랜드 태도에 미치는 영향에 관한 연구

학위논문(석사)--서울대학교 대학원 :경영학과 경영학전공,2002.Maste

(A) comparative scanning electron microscopic study on cleansing efficacy of several methods for cleaning dentures

치의학과/석사[한글] 비위생적인 의치관리는 의치구내염을 유발시키며 심미적 문제와 구취의 원인이 된다. 따라서 의치면에 형성된 침착물 제거를 위한 효과적인 세척방법이 개발되어 왔으며, 기존 세척방법은 크게 화학적 세척방법과 기계적 세척방법으로 구분되어 사용되고 있다. 그러나 여러 가지 세척방법의 세척효과에 관한 비교 연구는 사용된 연구방법에 따라 다양한 차이를 보이고 있다. 이에 저자는 주사전자 현미경이 수복면에 형성된 치태 관찰에 우수한 방법임에 착안하여, 상품용 세척제(Polident)와 가정용 표백세제인 차아염소산나트륨 희석용액(유한락스) 그리고 초음파 세척기(Mettler Electronics, Corp.)의 세균 및 점액질층에 대한 세척효과를 비교하기 위하여, Y대학에 재학중인 학생 및 수련의 8명(남자5명, 여자3명: 연령 21∼26세)을 대상으로, 각 실험 대상자의 구강내에 치태형성을 위한 시편들을 48시간 동안 장착시킨 후, 대조군 및 위의 3가지 방법에 따라 세척된 각 시편들에 대한 2,000배율의 주사전자 현미경 사진을 얻었다. 이 현미경 사진을 이용하여 각 세척방법에 따른 세척효과를 비교 분석한 결과 다음과 같은 결론을 얻었다. 1. 위의 3가지 세척방법 모두는 세척효과가 있었다. (P≤0.05) 2. 차아염소산나트륨 희석용액과 초음파 세척기의 세척효과는 Polident보다 우수하였다. (P≤0.05) 3. 차아염소산나트률 희석용액과 초음파 세척기 사이의 세척효과에는 유의의 차가 없었다. (P〉0.05) [영문] The purpose of this study was to compare the cleansing performance of a commercial cleanser (Polident), a diluted solution of sodium hypochlorite as a house-hold bleaching cleanser (Yuhanrox) and an ultrasonic(Mettler Electronics Corp.) on vivo plaque deposits by using a scanning electron microscope. Eight individuals(5 males, 3 females with ages ranging from 21 to 26) were selected for the study form Y university, and each of them was inserted with specimens for plaque accumulation in their oral cavities for 48hrs. Following the plaque accumulation period, the specimens were removed and cleaned by each cleansing method, them scanning electron micrographs were made from the specimens of 8 subjects at a magnification of X2,000. Throughout the micrographic study, cleansing efficacies were compared like below. 1. All of the above three methods had cleansing efficacy.(P≤0.05) 2. The diluted solution of sodium hypochlorite and ultrasonic cleaner had more cleansing efficacy than that of the commercial cleanser(Polident).(P≤0.05) 3. The cleansing efficacy between diluted solution of sodium hypochlorite and the ultrasonic cleaner had no significant differences.(P〉0.05)restrictio

The Effect of Loyalty toward Online Brand Community on Brand Attitude and Purchase Intention

There have been few studies regarding online community, particularly that of brands, despite increasing importance not only as a direct communication channel between a company and the customers but also as medium of voluntary information exchange among consumers. The present study aims to contribute to the understanding of the role of online brand community in developing and enhancing brand equity, in terms of brand attitude and the customers’ purchase intention. Empirical study utilizing survey data indicates the following. First, the higher the extent to which the member experiences fulfilled needs, membership, influence, and emotional ties, the greater their loyalty toward the online brand community, measured by frequency of visits, amount of participation and shared information, etc. Second, loyalty toward the online brand community turns out to be positively correlated with brand knowledge, brand attitude, and purchase intention. Finally, brand knowledge works for more favorable attitude toward the brand, and then positive brand attitude leads to greater purchase intention. The empirical results provide several managerial insights for the marketers actively seeking to utilize online communities as effective marketing channel