• 한국건설순환자원학회논문집
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• 제8권4호
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• pp.581-589
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• 2020

본 논문에서는 수화반응이 가능한 결정성장형 무기재료를 사용하여 고상 캡슐을 제조하였으며, 고상 캡슐 혼합에 따른 자기치유 모르타르의 품질 및 역학적 치유 특성을 평가하였다. 고상 캡슐은 시멘트 질량에 대하여 5% 혼합하였다. 압축하중 재부하 실험결과 Plain의 자연 치유 효과에 대하여 평균적으로 약 20% 수준을 향상시키는 것으로 나타났으며, 탄성범위의 경우 치유재령 7일에 약 79% 및 치유재령 28일에 98%의 치유율이 나타났다. 휨하중 재부하 실험결과, 탄성범위의 경우 치유재령 7일에 약 79% 및 치유재령 28일에 98%의 치유율이 나타났다. 이러한 결과를 통하여, 고상 캡슐의 치유성능은 투수시험에 의한 내구적 특성 외에도 강도와 같은 역학적 치유 특성에도 영향이 있는 것으로 판단되며, 고상 캡슐의 혼합에 따라 강도가 감소하는 경향이 있으므로 이에 대한 보완이 필요하다고 판단된다.

• 대한수의학회지
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• 제39권5호
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• pp.974-985
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• 1999

Osteoporosis is defined as a decrease in bone mass that leads to an increased risk of fracture. The therapeutic effect of $1{\alpha}$,25 dihydroxycholecalciferol, the hormonal form of vitamin $D_3$ that mediates calcium translation in intestine and bone, on the healing process of fracture has still been controversial. These studies were designed to understand the healing process of normal fibular fracture, the osteoporotic changes after ovariectomy, and the therapeutic effects of $1{\alpha}$,25 dihydroxycholecalciferol on the osteoporotic fracture in rats. The simple transverse fractures of rat fibulae were produced with a rotating diamond saw. The changes of the biochemical and mechanical indices of rats were investigated. The mechanical study based on bending test revealed the healing of the fibular fracture in the 5th week after simple transverse fracture. The osteoporosis impaired more the healing of osteoporotic fibular fracture than normal non-osteoporotic fibular fracture. The healing process of osteoporotic fracture was facilitated by the treatment with $1{\alpha}$,25 dihydroxycholecalciferol, however, was delayed more than the healing process of normal fracture. The bone strength based on the bending test also confirmed this tendency. The bone strengths in the 5th week after fracture of normal bone, osteoporotic bone, and $1{\alpha}$,25 dihydroxycholecalciferol-treated osteoporotic bone were 75%, 41%, and 67%, respectively, in comparison with those of intact bone. In conclusion, $1{\alpha}$,25 dihydroxycholecalciferol was effective in promoting the osteoporotic fracture healing.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 춘계학술발표대회 논문집
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• pp.190-193
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• 2004

Two different diene monomers [dicyclopentadiene (DCPD) and 5-ethylidene-2-norbomene (ENB)] as self­healing agent for polymeric composites were microencapsuled by in-situ polymerization of urea and formaldehyde. The healing agents were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Exothermic reaction and glass transition temperature from DSC and storage modulus (G') and tan $\delta$ from DMA curves were analyzed for the samples cured for 5 min and 24 h in the presence of different amounts of catalyst. Micorcapsules were successfully formed for both diene monomers. Microcapsules containing the healing agent were manufactured and its thermal properties were characterized by thermo gravimetric analysis (TGA). Optical microscope (OM) and particle size analyzer (PSA) were employed to observe morphology and size distribution of microcapsules, respectively. Comparison of the two self-healing agents and their microcapsules with the two was made in this study.

• 한국건설순환자원학회논문집
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• 제10권1호
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• pp.92-100
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• 2022

본 논문에서는 SC가 시멘트 복합재료의 균열 자기치유 성능 및 역학적 회복성능에 미치는 영향을 평가하기 위하여 캡슐화된 팽창성 무기재료 기반 고상 치유재를 제조하였다. SC는 시멘트 복합재료에 혼합하여 기초특성, 투수시험, 하중 재부하 시험을 평가하였다. SC는 시멘트 복합재료의 플로우를 다소 향상되었으며, 압축강도는 약 10 % 감소하였다. 또한 휨강도의 경우 약 30 % 감소하였다. SC를 시멘트 복합재료에 5 % 혼합할 경우, Plain의 균열 자기치유율이 약 𝜟10 % 수준을 향상시키는 효과가 있는 것으로 나타났으며, 하중 재부하 실험 결과, Plain의 역학적 회복율을 약 𝜟20 % 수준을 향상시키는 것으로 나타났다. 균열 자기치유율과 하중 재부하 시험에 의한 역학적 회복율의 상관관계를 분석한 결과, SC로 인하여 Plain의 치유면적을 증대시킬 수 있는 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.508-511
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• 2004

This study focused on the effect of autonomic microcapsules on the mechanical properties of structural material. Several types of microcapsules with healing agents were manufactured by varying agitation speed of high speed stirrer. The size distribution of microcapsules was measured by a particle size analzer. The epoxy specimens embedded with microcapsules were manufactured and the degree of cure of such epoxy specimen was measured by a differential scanning calorimetry. The tensile modulus and tensile strength in epoxy specimens embedded with microcapsules were evaluated in order to investigate the effects of microcapsules on mechanical properties of structural materials. The configuration of microcapsules and morphology of fracture surfaces for the epoxy specimen were examined by an optical microcope and a scanning electron microscope. According to the results, tensile strength of the epoxy specimen embedded with microcapsules was indicated a little reduction, but tensile modulus was not much affected on microcapsules.

• Macromolecular Research
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• 제17권7호
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• pp.533-537
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• 2009

This paper introduces a modified electro spinning system for biomedical wound-healing applications. The conventional electrospinning process requires a grounded electrode on which highly charged electro spun ultrafine fibers are deposited. Biomedical wound-healing membranes, however, require a very low charge and a low level of remnant solvent on the electrospun membrane, which the conventional process cannot provide. An electrohydrodynamic process complemented with field-controllable electrodes (an auxiliary electrode and guiding electrodes) and an air blowing system was used to produce a membrane, with a considerably reduced charge and low remnant solvent concentration compared to one fabricated using the conventional method. The membrane had a small average pore size (102 nm) and high porosity (85.1%) for prevention of bacterial contamination. In vivo tests on rats showed that these directly electro spun fibrous membranes produced using the modified electro spinning process supported the good healing of skin bums.

• Composites Research
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• 제28권6호
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• pp.395-401
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• 2015

본 연구에서는 자가손상보수에 적용되는 Grubbs' catalyst의 열안정성과 자가치료제와의 반응성을 조사하였다. 이를 위해 제조사에서 공급된 4종류를 고려하였으며 제조사에서 공급받은 상태와 기계적으로 분쇄시킨 상태로 시험하였다. 자가치료제는 Dicyclopentadiene (DCPD)과 5-ethylidene-2-norbonene (ENB)을 적절한 비율로 혼합한 4종류를 고려하였다. 촉매의 열안정성을 조사하기 위해 시차주사 열량측정장치를 통해 온도에 따른 열흐름 변화를 측정하였다. 자가치료제와의 반응성을 평가하기 위해 촉매와 혼합된 자가치료제의 반응열을 측정하였다. 이때 촉매는 자가치료제와 반응할 때의 최대온도와 최대온도 도달시간을 고려하여 Fluka Chemika Grubbs' catalyst를 적용하였다. 연구결과에 따르면 촉매는 제조사에 따라 다른 형상을 나타내며 입자의 크기가 작은 촉매가 자가치료제와 높은 반응성을 나타내었다. ENB의 혼합비가 높은 자가치료제가 촉매와 혼합되면 최대온도는 증가하고 최대온도 도달시간은 빨라졌다. 또한 촉매의 양이 많을수록 최대온도는 높아지고 최대온도 도달시간은 빨라졌다. 촉매의 열안정성과 자가치료제와의 반응성을 고려할 때 0.5 wt% 촉매와 D3E1 자가치료제가 자가손상보수를 위한 최적 조건임을 알 수 있었다. 마지막으로 노출된 분위기 온도에 따라 촉매에 열분해가 발생할 수 있기 때문에 촉매가 열안정성을 갖는 온도보다 높은 온도에 노출되지 않도록 하여야 한다.

• Macromolecular Research
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• 제12권5호
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• pp.478-483
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• 2004

Two different diene monomers [dicyclopentadiene (DCPD) and 5-ethylidene-2-norbornene (ENB)] as self-healing agents for polymeric composites were microencapsuled by in situ polymerization of urea and formaldehyde. We obtained plots of the storage modulus (G') and tan $\delta$ as a function of cure time by using dynamic mechanical analysis to investigate the cure behavior of the unreacted self-healing agent mixture in the presence of a catalyst. Glass transition temperatures (T$\_$g/) and exothermic reactions of samples cured for 5 and 120 min in the presence of different amounts of the catalyst were analyzed by differential scanning calorimetry. Of the two dienes, ENB may have advantages as a self-healing agent because, when cured under same conditions as DCPD, it reacts much faster in the presence of a much lower amount of catalyst, has no melting point, and produces a resin that has a higher value of T$\_$g/. Microcapsules containing the healing agent were successfully formed from both of the diene monomers and were characterized by thermogravimetric analysis. Optical microscopy and a particle size analyzer were employed to observe the morphology and size distribution, respectively, of the microcapsules. The microcapsules exhibited similar thermal properties as well as particle shapes and sizes.

• 대한기계학회논문집A
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• 제29권6호
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• pp.787-794
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• 2005

Nowadays chronic degenerative diseases such as arthritis are increasing rapidly, even though acute infectious diseases are decreasing due to the advance of modern medicine. Although many of remedies are developed for arthritis healing, there is no precise medical prescription, and pathogenesis is not examined exactly. In this study, we confirmed gene expression of BMP 1A, BMP 2B, osteonectin and MGP which are genes related with bone formation in osteoblast by using ultrasonic stimulation. Through this study, we also evaluated the fact that ultrasound could be applied to arthritis healing by making activated osteoblast induce remodeling of cartilage. As a result of this research, BMP 2B and MGP have higher rates of expression in specific ultrasound mode. In conclusion, it is expected that ultrasound could be used efficiently for healing arthritis if we use ultrasounds according to symptoms of arthritis on reasonable terms.

• 대한기계학회논문집A
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• 제30권3호
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• pp.219-230
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• 2006

Digital CAD models are one of the most important assets the manufacturer holds. The trend toward concurrent engineering and outsourcing in the distributed development and manufacturing environment has elevated the importance of high quality CAD model and its efficient exchange. But designers have spent a great deal of their time repairing CAD model errors. Most of those poor quality models may be due to designer errors caused by poor or incorrect CAD data generation practices. In this paper, we propose a rule-based approach for healing CAD model errors. The proposed approach focuses on the design history data representation from a commercial CAD model, and the procedural method for building knowledge base to heal CAD model. Through the use of rule-based approach, a CAD model healing system can be implemented, and experiments are carried out on automobile part models.