• 대한기계학회논문집A
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• 제25권4호
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• pp.564-573
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• 2001

The mechanical properties of short carbon/glass fiber reinforced polypropylene are experimentally measured as functions of fiber content and nozzle diameter. Also, these properties are compared with the survival rate of reinforced fibers and fiber volume fraction using image analysis after pyrolytic decomposition. The survival rate of fiber aspect ratio as well as fiber volume fraction is influenced by injection processing condition, the used materials and mold conditions such as diameter of nozzle, etc. In this study, the survival rate of fiber aspect ratio is investigated by nozzle size variations in injection/mold sides. It is found that the survival rate of glass fiber is higher that the survival rate of glass fiber is higher than that of carbon fiber. Both tensile modulus and strength of short-fiber reinforced polypropylene are improved s the fiber volume fraction and nozzle diameter are increased.

• Journal of Chest Surgery
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• 제25권2호
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• pp.137-148
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• 1992

Until March 1991, 435 St. Jude Medical valves and 330 CarboMedics valves were implanted in 358 and 251 patients, respectively. 300 patients were male and 309 were female with the mean age of 35.6 years[from 2 month to 68 years]. 458 valves were implanted in the mitral, 272 in the aortic, 25 in the tricuspid, and 10 in the pulmonic position. Postoperatively, all patients except for very young patients were given coumadin with or without dipyridamole for anticogulation Operative mortality was 7.3%[45 deaths per 618 operations]. A total follow-up of 1244.8 patient-years was achieved for the operative survivors with a follow-up rate of 96.8%, [mean follow-up period=26.3 months /patient, ranging from 1 to 80 months]. Functional improvement was evident; 66.7% of these patients were in NYHA functional class III or IV preopratively, whereas 98.4% are in class I or II pos-toperatively. There occurred 13 late deaths[7 valve-related] and 55 valve-related complications. Linearized rates of late death and valve-related complications were 1.0%/ patient-year, 4.42%/patient-year, respectively. Rates of thromboembolism, anticoagluation-related hemorrhage were 1.12%/patient-year, 1.69% /patient-year, respectively. Actuarial survival at 5 years is 96.0% and complication-free survival at 5 years is 83.9%. No difference in survival and incidence of complications was found between the St. Jude and CarboMedics valves. On the basis of this experience, we believe that the pyrolytic carbon bileaflet mechanical valves are safe and preferable choice among current valve prostheses.

• 한국세라믹학회지
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• 제45권4호
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• pp.238-244
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• 2008

Modeling and FEM analysis on Boron Nitride and/or Pyrolytic Carbon coating layers on SiC fibers under indentation contact loadings are investigated. Especially this study attempts to model the mechanical behavior of the SiC fibers with and without coatings. Tyranno S grade and Tyranno LoxM grade of SiC are selected for fiber and Boron Nitride and/or Pyrolytic Carbon as coating material. The modeling is performed by SiC fiber without coating layer, which includs single(BN or PyC) and double(BN-PyC or PyC-BN) coating layer. And then the analysis is performed by changing a type of coating layer, a type of fiber and coating sequence. In this study, the concepts of modeling and analysis techniques for optimum design of BN and PyC coating process on SiC fiber are shown. Results show that stresses are reduced when indentation contact loading applies on the material having lower elastic modulus.

• Clinics in Shoulder and Elbow
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• 제27권1호
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• pp.117-125
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• 2024

While shoulder hemiarthroplasty is still used to treat young patients with shoulder pathology, the use of this procedure has substantially declined in recent years due to its significant complication profile. Glenoid wear with arthrosis is one of the major postoperative complications following shoulder hemiarthroplasty, and efforts to prevent this complication led many scientists to explore alternative weight-bearing surfaces on arthroplasty implants to decrease joint wear and improve patient outcomes. Pyrolytic carbon, or pyrocarbon, is a material that has better biocompatibility, survivorship, strength, and wear resistance compared to the materials used in traditional shoulder hemiarthroplasty. Pyrocarbon implants have been used in orthopedics for over 50 years; recently, their utility in shoulder hemiarthroplasty has garnered much interest. The purpose behind the use of pyrocarbon in shoulder hemiarthroplasty is to decrease the risk of progressive glenoid wear, especially in young active patients in whom joint preservation is important. Promising survivorship and outcomes have been demonstrated by recent studies, including limited glenoid wear following pyrocarbon hemiarthroplasty. Nevertheless, these clinical studies have been limited to relatively small case series with limited long-term follow-up. Accordingly, additional research and comparative studies need to be conducted in order to properly assess the therapeutic efficacy and value of pyrocarbon hemiarthroplasty.

• 유기물자원화
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• 제14권2호
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• pp.101-111
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• 2006

본 연구에서는 폐플라스틱의 재활용방법 (물질재활용, Refused Derived Fuel(RDF), 고로원료화 및 유화)에 대한 환경 영향을 분석하기 위하여 전과정평가(LCA)가 수행되었다. 이 연구에서는 6가지 환경영향 범주를 사용하였다. 폐플라스틱의 재활용방법 중 가장 큰 영향을 미치는 범주는 지구온난화로 나타났으며, 나머지들의 영향은 미비한 것으로 나타났다. 지구온난화의 영향을 살펴보면 물질재활용, RDF화 및 고로원료화에 대해서는 환경성이 음(-)의 값으로 나타났으며, 이러한 현상은 신재 플라스틱의 대체재로 사용함으로써 환경부하 삭감효과가 크기 때문인 것으로 밝혀졌다. 그러나, 유화는 양(+)의 값으로 나타나 환경부하가 증가하는 것으로 나타났으며, 이것은 사용량이 많은 전력의 생산과정에서 발생하는 $CO_2$가 주원인으로 밝혀졌다. 오존층파괴에 대한 영향은 유화방법이 환경부하가 크게 나타났으며, 이러한 현상은 유화 공정자체에서 발생되는 오존층파괴 물질에 의한 영향으로 판단되었다. 본 연구 결과들은 폐플라스틱 재활용을 향상시키는데 유용한 자료로 활용될 수 있음을 보여주었다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.1990-1995
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• 2008

The thermochemical recycling of waste tires by pyrolysis is studied to recover the value added three by-products; a pyrolytic carbon black, a pyrolytic oil, and a non-condensable gas. The exhausted energy from pyrolysis of waste tires is converted for electricity power and process steam in cogeneration system. The characteristics of the pyrolysis recovered by-products as alternative energy resource are investigated with the design of a demonstration and a commercialization plant including cogeneration system, as called integrated pyrolysis cogeneration system.

• Carbon letters
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• 제4권1호
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• pp.36-39
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• 2003

Carbon and carbon-based materials are used in nuclear reactors and there has recently been growing interest to develop graphite and carbon based materials for high temperature nuclear and fusion reactors. Efforts are underway to develop high density carbon materials as well as amorphous isotropic carbon for the application in thermal reactors. There has been research on coated nuclear fuel for high temperature reactor and research and development on coated fuels are now focused on fuel particles with high endurance during normal lifetime of the reactor. Since graphite as a moderator as well as structural material in high temperature reactors is one of the most favored choices, it is now felt to develop high density isotropic graphite with suitable coating for safe application of carbon based materials even in oxidizing or water vapor environment. Carboncarbon composite materials compared to conventional graphite materials are now being looked into as the promising materials for the fusion reactor due their ability to have high thermal conductivity and high thermal shock resistance. This paper deals with the application of carbon materials on various nuclear reactors related issues and addresses the current need for focused research on novel carbon materials for future new generation nuclear reactors.

• 대한화학회지
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• 제60권5호
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• pp.299-309
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• 2016

In this study, the physicochemical and electrochemical properties of carbon nanomaterials and synthesized nano-carbon/Si composites were studied. The nano-carbon/Si composites were ball-milled to a nano size and coated with pyrolytic carbon using Chemical Vapor Deposition (CVD). They were then finely mixed with respective nano-carbon materials. The physicochemical properties of samples were analyzed using Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Raman spectroscopy, X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and surface area analyzer. The electrochemical characteristics were investigated using the galvanostatic charge-discharge and cyclic voltammetry (CV) measurements. Three-electrode cells were fabricated using the carbon nanomaterials and nano-carbon/Si composites as anode materials and LiPF₆ and LiClO₄ as electrolytes of Li secondary batteries. Reversibility using LiClO₄ as an electrolyte was superior to that of LiPF₆ as the electrolyte. The initial discharge capacities of nano-carbon/Si composites were increased compared to the initial discharge capacities of nano-carbon materials.

• 한국세라믹학회지
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• 제52권4호
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• pp.284-289
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• 2015

This study examined carbon layer coating on silicon carbide (SiC) fibers by utilizing solid-state and wet chemistry routes to confer toughness to the fiber-reinforced ceramic matrix composites, as an alternative to the conventional pyrolytic carbon (PyC) interphase layer. Electrophoretic deposition (EPD) of carbon black nanoparticles using both AC and DC current sources, and the vacuum infiltration of phenolic resin followed by pyrolysis were tested. Because of the use of a liquid phase, the vacuum infiltration resulted in more uniform and denser carbon coating than the EPD routes with solid carbon black particles. Thereafter, vacuum infiltration with controlled variation in phenolic resin concentration, as well as the iterations of infiltration steps, was improvised to produce a homogeneous carbon coating having a thickness of several hundred nanometers on the SiC fiber. Conclusively, it was demonstrated that the carbon coating on the SiC fiber could be achieved using a simpler method than the conventional chemical vapor deposition technique.

• Journal of the Korean Wood Science and Technology
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• 제40권6호
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• pp.445-453
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• 2012

본 연구에서는 백합나무의 급속 열분해 공정에서 시료의 입자크기 및 함수율 조건이 열분해 산물(가스, 바이오오일, 바이오촤)의 수율과 물리 화학적 특성에 미치는 영향을 구명하였다. 시료의 함수율이 낮을수록 바이오오일의 수율은 증가하였으며 시료의 입자 크기는 수율 변화에 큰 영향을 미치지 않았다. 각 조건별로 생성된 바이오오일은 20~30%의 수분 함량과 pH 2.2~2.4, 발열량 16.6~18.5 MJ/kg의 수준을 나타내었으며 바이오오일 내 수분 함량은 높은 함수율 시료 조건에서 증가하는 것을 확인하였다. 바이오촤의 경우 80% 이상이 탄소로 이루어져있으며 발열량은 26.2~30.1 MJ/kg 수준으로 측정되었다.