• Journal of information and communication convergence engineering
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• 제11권4호
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• pp.288-292
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• 2013

In this paper, a carbon implant is investigated in detail from the perspectives of performance advantages and side effects for the thick n-type metal-oxide-semiconductor field-effect transistor (n-MOSFET). Threshold voltage ($V_{th}$) adjustment using a carbon implant significantly improves the $V_{th}$ mismatch performance in a thick (3.3-V) n-MOS transistor. It has been reported that a bad mismatch occurs particularly in the case of 0.11-${\mu}m$ $V_{th}$ node technology. This paper investigates a carbon implant process as a promising candidate for the optimal $V_{th}$ roll-off curve. The carbon implant makes the $V_{th}$ roll-off curve perfectly flat, which is explained in detail. Further, the mechanism of hot carrier injection lifetime degradation by the carbon implant is investigated, and new process integration involving the addition of a nitrogen implant in the lightly doped drain process is offered as its solution. This paper presents the critical side effects, such as Isub increases and device performance shifts caused by the carbon implant and suggests an efficient method to avoid these issues.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제37권
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• pp.34.1-34.14
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• 2015

Background: Over the past 30-40 years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8 years. Methods: Mandibular reconstruction (8-10 years ago) was performed with pure (99.99 %) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8 years to a sterilized, but not implanted one. Results: Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants. Conclusions: The surface morphology and the structure were not changed after 8 years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates.

• 대한치과보철학회지
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• 제46권2호
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• pp.137-147
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• 2008

임플랜트 보철물에서 각 구성 요소를 연결하는 나사 풀림 현상이 흔히 발생하고 있다. 나사 풀림을 최소화하기 위해서 연결 구성 부품 사이의 압축력을 최대로 하는 것이 중요한데, 나사 신장의 허용 한계 내에서 조임회전력을 증가시켜 나사 내부의 인장력 즉 전하중을 극대화하기 위해서는 마찰 계수를 감소시켜 초기 조임회전력의 손실을 최소화해야 한다. 건조 윤활제를 나사 표면에 코팅한 나사들이 전하중을 증가시키고 나사 풀림을 감소시키나 나사의 반복체결에 따른 코팅표면의 마모가 문제점으로 지적되고 있다. 최근 내마모성이 우수하며 동시에 나사의 마찰 저항을 최소화할 수 있는 텅스텐 카바이드/탄소 코팅을 이용한 나사가 임상에 사용되고 있으나 실제적으로 연결부 안정성에 미치는 영향에 관한 연구는 미미한 편이다. 이에 본 연구에서는 external butt joint 형태를 가지는 US II 시스템과 one stage용 8도의 internal cone 연결형태의 SS II 시스템 및 11도의 internal cone 연결형태의 GS II 시스템에서 티타늄 합금 나사의 텅스텐 카바이드/탄소 코팅이 지대주 나사 풀림에 미치는 영향을 알아보기 위하여 100만 회 반복 하중 전후의 풀림회전력 및 상실률을 비교한 결과 다음과 같은 결론을 얻었다. 1. 초기 풀림회전력은 티타늄 합금나사보다 텅스텐 카바이드/탄소 코팅 나사를 사용한 경우 작게 나타났으며 (P<.01), 동일 나사를 사용한 경우에는 임플랜트 시스템 간에 차이가 없었다 (P>.05). 2. 반복하중에 따른 풀림회전력의 상실률은 두 나사 모두에서 external butt joint 형태의 US II 시스템이 internal cone 연결형태의 SS II 와 GS II 시스템 보다 크게 나타났으나, SS II 와 GS II 시스템 사이에는 차이를 보이지 않았다 (P<.01). 3. 텅스텐 카바이드/탄소 코팅 나사를 사용한 경우 티타늄 합금 나사에 비해 모든 시스템에서 반복하중 후 풀림회전력 상실률이 작게 나타났으며 (P<.01), 코팅 나사 사용으로 인한 상실률의 감소차는 임플랜트 시스템 간에 차이를 보이지 않았다 (P>.05).

• 대한치과보철학회지
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• 제17권1호
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• pp.89-90
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• 1979

• 한국전산구조공학회논문집
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• 제31권1호
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• pp.23-29
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• 2018

무릎 임플란트에서 접촉압력이 마모에 큰 영향을 미친다. 본 연구에서는 본 연구기관에서 개발한 무릎 임플란트 모델을 이용하여 유한요소해석을 하였다. 연구와 산업에서 실제로 사용하는 조합을 이용하여 총 10가지의 무릎 임플란트의 재료조합에 대한 접촉압력을 분석하였다. 무릎이 30도, 45도 60도 기울어져있을 때의 하중을 가하여 접촉압력을 구하였다. 접촉압력을 계산한 결과 티타늄합금-UHMWPE 조합에서 가장 작은 접촉압력이 나왔다. UHMWPE의 경우 대퇴골부에 어떠한 재료를 사용하여도 접촉압력이 크게 변하지 않았다. 접촉압력이 가장 큰 조합과 작은 조합을 비교하였을 때 0.77% 차이를 보였다. 반면에 Carbon/PEEK 복합재료의 경우 접촉압력이 가장 큰 경우와 작은 경우를 비교하였을 때 5.3% 차이를 보였다. 이를 통해 Carbon/PEEK 복합재료를 베어링부로 사용할 경우 대퇴골부의 재료가 마모에 영향을 미침을 알 수 있다. 본 연구는 무릎 임플란트 마모예측과 마모를 최소화 연구에 도움이 될 것이라 생각한다.

• The Journal of Advanced Prosthodontics
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• 제16권3호
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• pp.189-199
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• 2024

PURPOSE. This study was conducted to evaluate the effects of plasma treatment of sandblasted and acid-etched (SLA) titanium implants on surface cleansing and osseointegration in a beagle model. MATERIALS AND METHODS. For morphological analysis and XPS analysis, scanning electron microscope and x-ray photoelectron spectroscopy were used to analyze the surface topography and chemical compositions of implant before and after plasma treatment. For this animal experiment, twelve SLA titanium implants were divided into two groups: a control group (untreated implants) and a plasma group (implants treated with plasma). Each group was randomly located in the mandibular bone of the beagle dog (n = 6). After 8 weeks, the beagle dogs were sacrificed, and volumetric analysis and histometric analysis were performed within the region of interest. RESULTS. In morphological analysis, plasma treatment did not alter the implant surface topography or cause any physical damage. In XPS analysis, the atomic percentage of carbon at the inspection point before the plasma treatment was 34.09%. After the plasma treatment, it was reduced to 18.74%, indicating a 45% reduction in carbon. In volumetric analysis and histometric analysis, the plasma group exhibited relatively higher mean values for new bone volume (NBV), bone to implant contact (BIC), and inter-thread bone density (ITBD) compared to the control group. However, there was no significant difference between the two groups (P > .05). CONCLUSION. Within the limits of this study, plasma treatment effectively eliminated hydrocarbons without changing the implant surface.

• 대한치과보철학회지
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• 제44권2호
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• pp.229-242
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• 2006

Statement of problem: In order to increase preload with reducing the friction coefficient, abutment screws coated with pure gold and Teflon as dry lubricant coatings have been introduced. But the reported data indicate that if screw repeated tightening and loosening cycle, an efficiency of increasing preload was decreased by screw surface wearing off. Purpose: This study was to evaluate the influence of tungsten carbide/carbon coating, which has superior hardness and frictional wear resistance, on the preload of abutment screws and the stability of coating surface after repeated closures. Material and method: The rotational values of abutment screws and the compressive forces between abutment and fixture were measured in implant systems with three different joint connections, one external butt joint and two internal cones. Moreover the stability and the alteration of coating surface were examined by comparison of the compressive force and the removable torque values during 10 consecutive trials, observation with scanning electron microscope and analyzed the elemental composition with energy dispersive x-ray spectroscopy Results and conclusion: 1. Application of coating resulted in significant increase of compressive force in all implant systems(P<.05). The increasing rate of compressive force by coating in external butt joint was gloater than those in internal cones (P<.05). 2. Coated screw showed the significant additional rotation compared to non-coated screw in all implant systems (P<.05). There were no significant differences in the increasing rate of rotation among implant systems (P>.05). 3. Removable torque values were greater with non-coated screw than that with coated screw (P<.05). 4. Coated screw showed insignificant variations in the compressive forces during 10 consecutive trials(P>.05) 5. After repeated trials, the surface layer of coated screw was maintained relatively well. However surface wearing and irregular titanium fragments were found in non-coated screw.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2010년도 춘계학술발표대회
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• pp.43.2-43.2
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• 2010

Most of previous methods for the dispersions of carbon nanotube were achieved by various chemical functionalizations. In this study, however, we generated highly water dispersed carbon nanofibers by altering intrinsic materials property only, such as crystallinity of outer layers of carbons, without chemical treatment. Although most of chemical functionalization requires acidic treatment and may degrade their chemical functions by interacting with other molecules, suggested strategy demonstrated a simple but chemically non-degradable carbon nanotube for the application of various medical applications, such as drug delivery system and implant coatings.Furthermore, protein adsorption was increased by the reducing surface crystalinity since outer activated surface induced more adsorption of oxygen and eventually greater protein adsorption than pristine carbon nanofibers.

• Carbon letters
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• 제6권1호
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• pp.15-24
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• 2005

Sixteen clinically healthy New Zealand white rabbits of either sex were divided into two equal groups I and II of 8 animals each. Under thiopental sodium (2.5%) anaesthesia a linear full thickness abdominal wall defect of 3 cm in length was created and repaired with continuous suture pattern using 3000 filaments of carbon fibres and 1~0 black braided nylon suture, ingroup I and II respectively. Increased vascularity was observed in carbon fibres (group I) and on day 30 the carbon fibres were covered by white fibrous tissue. Significantly higher (P < 0.05) values of glucose was seen on day 14 in group I, whereas, decrease in glucose value was observed in group II. Histopathologically, the carbon fiber implant induced extensive fibrous tissue (collagen fiber) reaction. Negligible inflammatory cells in the stroma indicate the host tissue tolerance to carbon fibers. Histochemically, gradually increased alkaline phosphatase activity up to day 14 in group I, suggested the proliferation of fibroblasts in early stages.

• 대한치과기공학회지
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• 제40권1호
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• pp.41-47
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• 2018

Purpose: The purpose of this study was to analyze the biomechanical properties of the dental implants on the supporting bone using three-dimensional finite element method when three different abutment materials were applied to the implant system. Methods: Three different dental implant models were fabricated by applying Ti, PEEK, and CRE-PEEK (60% carbon-reinforced PEEK) to abutment material. The abutment and connecting screw from the fixture was applied with a tightening torque of 20 Ncm. And then, total loads of 150 N were applied in an $30^{\circ}oblique$ direction (to the vertical). The structural stability of dental implants on the supporting bone was analyzed using Von Mises stress and principal stress values. Results: The maximum tensile stress of the cortical bone was highest at 12.6 MPa in the PEEK abutment (Model-B). Ti abutment (Model-A) and CRE-PEEK abutment (Model-C) showed similar stress distributions (10.6 and 10.3 MPa, respectively). And the maximum compressive principal stress was similar in all models. The Von Mises stress value delivered to the bone around the implant was highest at 16.5 MPa in Model-B. On the other hand, Model-A and C showed similar stress distributions (14.0 and 13.8 MPa, respectively). In addition, the maximum equivalent stress applied to the abutment was highest at 629.8 MPa in Model-A. The stress distribution in Model-C was 573.9 MPa. Whereas, Model-B showed the lowest value at 165.6 MPa. Conclusion : The dental implant supporting bone system using PEEK material seems to have the possibility of supporting bone fracture. It was found that the CRE-PEEK abutment can reduce the elastic deformation and reduce the stress value of the interfacial bone.