• 한국정밀공학회지
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• 제29권7호
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• pp.705-710
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• 2012

Research involving discomfort or pain related to haptic vibratory stimulation the for prosthesis users of myoelectrical hand is very lacking. Our objective of this study was to evaluate the displeasure and sensitivity of areas in forearm using vibration stimulation system between upper limb amputees and non-amputees. Twenty transradial amputees and forty non-amputees (20 youth, 20 elderly) were involved. We set up custom-made vibration stimulation system including eight actuators (4 medial parts and 4 lateral parts) and GUI-based acquisition system, to investigate changes of residual somatosensory sensibility and displeasure at proximal 25% of forearm. Eight vibration actuators were attached to the circumference of proximal 25% point of forearm at regular intervals. Sensitivity tests were used to stimulate the 120Hz and discomfort experiment was used to 37 ~ 223Hz. The subjective responses were evaluated by 10 point scale. The results showed that both groups were similar in sensitive areas. Response at around of radius was most sensitive than other areas in all subjects. Elderly group do not appear discomfort of vibrotactile; however, youth group and amputee presented discomfort of vibrotactile. Prosthesis with a vibrotactile feedback system should be developed considering the sensitivity. Furthermore, Future studies should investigate the scope of application of that principle.

• 구강회복응용과학지
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• 제33권2호
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• pp.135-142
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• 2017

컴퓨터를 이용한 CAD/CAM milling 방식이 치과 분야에도 적용됨에 따라 보다 분석적이고 정밀한 보철물이 제작 가능하게 되었다. 특히, 국소의치의 지대치로 사용되는 서베이드 크라운을 제작하는데 있어 이러한 디지털 방식의 정밀함은 국소의치의 삽입철거로와 언더컷 등이 정확하게 부여될 수 있게 한다. 본 증례는 상악의 다수 치아 상실을 보이는 환자에서 CAD/CAM을 이용하여 전자 서베잉을 통해 적절한 삽입철거로를 부여하고 지르코니아 서베이드 크라운을 제작하였다. 국소의치의 적합도는 우수했으며, 장착 후 안정성과 착탈 시의 유지력 또한 임상에서 적용하는 데에 문제가 없었다.

• 대한치과보철학회지
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• 제59권1호
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• pp.79-87
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• 2021

구강 스캐너를 이용한 디지털 인상과 CAD-CAM (Computer-aided design-computeraided manufacturing) 기술은 점차 발전하고 있다. 전통적인 인상 채득, 작업모형의 제작, 왁스 납형 제작 및 주조의 복잡한 과정이 단축되었으며 환자의 방문 횟수도 줄일 수 있게 되었다. 구강 스캐너 기술의 발전으로 디지털 인상의 정밀도와 정확성이 향상되었으며, 그 적응증은 보다 광범위한 부위의 고정성 치과보철물의 수복으로 점차 확대되어지고 있다. 본 증례 보고에서는 광범위한 부위의 고정성 임플란트 보철물의 수복을 위하여, 컴퓨터로 계획하고 가이드 수술용 템플레이트로 완전히 가이드된 수술을 하고, 즉시/조기 임플란트 보철물을 장착하였으며, 임시 보철물에서 최종 보철물로 전환하는 과정에서 구강스캐너의 지대주중첩 알고리즘을 활용하였다. 임플란트 수술 당일 획득한 구강스캔으로 맞춤형 지대주를 포함한 임시 보철물을 제작하여 활용하였으며, 최종 보철물은 임시 보철물에서의 맞춤형 지대주를 낀 채로 구강스캔하여 제작되었다. 이 과정에서 임시 보철물 장착 전에 미리 스캔해서 라이브러리화한 맞춤형 지대주 데이터를 구강스캐너 소프트웨어 '지대주 자동중첩 기능'으로 최종 디지털 인상에 자동적으로 매칭하였고, 치은연하마진인 부분도 지대주를 탈거하지 않고, 치은압배사 없이 정밀하게 획득할 수 있었다. 구강스캐너와 소프트웨어의 다양한 기술을 응용하여 임플란트 치료 과정을 디지털 워크플로우로 변화시킴으로써, 환자 불편감 및 치료 시간을 단축하였으며, 환자와 술자에게 모두 이롭고 예지성 있는 치료가 가능하였다.

• 구강회복응용과학지
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• 제38권3호
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• pp.127-137
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• 2022

지르코니아는 다양한 공정과정을 거쳐서 제작되며, 각각의 요소는 최종 보철물의 물성에 영향을 줄 수 있다. 특히 밀링과정과 소결과정이 모두 지르코니아 보철물의 최종 완성도(integrity)에 영향을 미칠 수 있다. 밀링머신은 대부분 초정밀 5축 가공방식을 채택하고 있으며 어떤 방식을 사용하고 밀링기구를 어떻게 관리하는가에 따라서도 결과가 달라진다. 밀링블록은 절삭의 효율성과 심미재현성에 따라 선택하는데 물성의 변화를 야기할 수 있음은 주의해야 한다. 소결방식은 입자성장과 광학적 특성에 영향을 미칠 수 있는데 속도를 조절하는 최근의 방식에 대해서는 추가적인 연구가 동반되어야 정확한 평가가 이루어질 수 있다. 소결온도 뿐 아니라 온도 유지시간도 최종결과물에 영향을 줄 수 있다.

• The Journal of Advanced Prosthodontics
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• 제15권1호
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• pp.22-32
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• 2023

PURPOSE. Digital technology has enabled improvements in the fitting accuracy of denture bases via milling techniques. The aim of this study was to evaluate the trueness and precision of digital and analog techniques for manufacturing complete dentures (CDs). MATERIALS AND METHODS. Sixty identical CDs were manufactured using different production protocols. Digital and analog technologies were compared using the reference geometric approach, and the Δ-error values of eight areas of interest (AOI) were calculated. For each AOI, a precise number of measurement points was selected according to sensitivity analyses to compare the Δ-error of trueness and precision between the original model and manufactured prosthesis. Three types of statistical analysis were performed: to calculate the intergroup cumulative difference among the three protocols, the intergroup among the AOIs, and the intragroup difference among AOIs. RESULTS. There was a statistically significant difference between the dentures made using the oversize process and injection molding process (P < .001), but no significant difference between the other two manufacturing methods (P = .1227). There was also a statistically significant difference between the dentures made using the monolithic process and the other two processes for all AOIs (P = .0061), but there was no significant difference between the other two processes (P = 1). Within each group, significant differences among the AOIs were observed. CONCLUSION. The monolithic process yielded better results, in terms of accuracy (trueness and precision), than the other groups, although all three processes led to dentures with Δ-error values well within the clinical tolerance limit.

• 한국정밀공학회지
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• 제24권7호
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• pp.133-138
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• 2007

It is important to understand the characteristics of amputee gait to develop more advanced prostheses. The aim of this study was quantitatively to analyze the stair climbing task for the above-knee amputee with a prosthesis and to predict muscle forces and joint moments at musculoskeletal joints by dynamic analysis. The three-dimensional musculoskeletal model of lower extremities was constructed by gait analysis and transformation software for one above-knee amputee and ten healthy people. The measured ground reaction forces and kinematical data of each joint by gait analysis were used as input data during inverse dynamic analysis. Lastly, dynamic analysis of above-knee amputee during stair climbing were performed using musculoskeletal models. The results showed that summed muscle farces of hip extensor of amputated leg were greater than those of sound leg but the opposite results were revealed at hip abductor and knee flexor of amputated leg. We could also find that the higher moments at hip and knee joint of sound leg were needed to overcome the flexion moment caused by body weight and amputated leg. In conclusion, dynamic analysis using musculoskeletal models may be a useful mean to predict muscle forces and joint moments for specific motion tasks related to rehacilitation therapy..

• International Journal of Precision Engineering and Manufacturing
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• 제9권1호
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• pp.30-33
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• 2008

Understanding the characteristics of amputee gait is key in developing more advanced prostheses. The aim of this study was to quantitatively analyze a stair-climbing task for transfemoral amputees with a prosthesis and to predict the muscle forces and joint moments at musculoskeletal joints using a dynamic analysis. A three-dimensional musculoskeletal model of the lower extremities was constructed from a gait analysis using transformation software for two transfemoral amputees and ten healthy people. The measured ground reaction forces and kinematical data of each joint from the gait analysis were used as input data for an inverse dynamic analysis. Dynamic analyses of an transfemoral amputee climbing stairs were performed using musculoskeletal models. The results showed that the summed muscle forces of the hip extensor of an amputated leg were greater than those of a sound leg. The opposite was true at the hip abductor and knee flexor of an amputated leg. We also found that higher moments at the hip and knee joints of the sound leg were required to overcome the flexion moment caused by the body weight and amputated leg. Dynamic analyses using musculoskeletal models may be a useful means to predict muscle forces and joint moments for specific motion tasks related to rehabilitation therapy.

• 한국정밀공학회지
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• 제31권12호
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• pp.1067-1076
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• 2014

To date, biomedical application of three-dimensional (3D) printing technology remains one of the most important research topics and business targets. A wide range of approaches have been attempted using various 3D printing systems with general materials and specific biomaterials. In this review, we provide a brief overview of the biomedical applications using 3D printing techniques, such as surgical tool, medical device, prosthesis, and tissue engineering scaffold. Compared to the other applications of 3D printed products, the scaffold fabrication should be performed with careful selection of bio-functional materials. In particular, we describe how the biomaterials can be processed into 3D printed scaffold and applied to tissue engineering area.

• 대한치과기공학회지
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• 제24권1호
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• pp.127-138
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• 2002

There are some cases that dental prosthesis does not operate as properly as expected in oral mouth. The reasons are such as a distortion of the mandibular, a fault of impression taking system or an extrusion of remaining teeth. One of dental prostheses to consider in the situations is the attachment which connects segment bridge. Active discussions are managed on theoretical side of this field but few on clinical side of it, which must be considered first. Accordingly I'd like to suggest a theoretical background for connect attachment of fixed segmented bridge. 1. As a bridge gets longer, burden on dental ligament is increased and the hardness of a bridge is lessened. 2. The flexibility of a bridge increases in ratio to 3 multiplication of the length and decreases in ratio to 3 multiplication of the width of occlusal surface and base of pontic. 3. Precision rest is needed to cope with the shake of teeth and the difference of axis direction among abutments. 4. Female part of the precision rest should be on middle abutment distal and male one on mesial of pontic. 5. Segmented attachment can be efficiently used to cope with long span bridgework and also in case that one piece casting can't be done because of slant of abutment.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.179-180
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• 2006

In this study, the effect of stem-end design on contact pressure and stress distribution in revision TKR was investigated using finite element method. The finite element model of tibia, including the cortical bone, the cancellous bone and canal, was developed based on CT images. The stem models with various stem lengths, diameters and frictional coefficients, and press-fit effects were considered. The results showed that the longer stem length, the stronger press-fit, the bigger stem diameter, and the higher frictional coefficient increased both peak contact pressure and the highest Von-Mises stress values. We hypothesized that peak contact pressure and Von-Mises stress distribution around the stem, may be related to the stem end pain. The results of this study will be useful to design the stem endand reduce the end-of-stem pain in revision TKR.