• 한국염색가공학회지
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• 제29권1호
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• pp.18-24
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• 2017

Meta-aramid fabric has been widely used as the reinforcement of composites due to its high flame resistance and tearing strength. Functionality such as abrasion resistance of fabric is very important for specialty fabrics used in car racing suits. In this study, to improve abrasion resistance property of meta-aramid fabric, silicon deposition was conducted by utilizing RF magnetron sputtering. The sputtering process parameters effects were investigated as sputtering power and substrate temperature. The obtained results suggest that the silicon deposition on the meta-aramid fabric has obvious effect upon increasing the abrasion resistance, the thermal insulation and the electric resistance condition for silicon deposition was established. In conclusion, the results of this study have made it possible to manufacture meta-aramids with higher abrasion strength.

• 대한치과보철학회지
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• 제38권4호
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• pp.500-509
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• 2000

In general, the three major oral functions of edentulous patients-mastication, phonation, esthetics-can be rehabilitated by the complete dentures, and both the resin based complete denture and the metal based complete denture are commonly used by many clinicians today. For the sake of many advantages such as the excellent thermal conductivity, low volumetric change, high strength, low risk of fracture and the better patient's adaptation, the metal based complete dentures are indicated to the several cases. But, there are common failures of these type of dentures mainly by the fracture or the debonding between the resin structures and the metal frameworks which is caused by the discrepancies of the flexural strength and the coefficient of thermal expansion. This is aggravated by the water contamination of the interface when exposed to the oral environment and results in the failure of complete denture treatment. So, the purpose of this study is to compare the bond strength and the fracture patterns of the gold alloy based and the Co-Cr alloy based complete dentures using the PMMA resins and the 4-META adhesive resins. The results of this study were as follows. 1. Both to the PMMA resin and the 4-META resin, the flexural bond strength of gold alloy is lower than that of Co-Cr alloy(P<0.05) 2. To the Co-Cr alloy, the bond strength of the 4-META resin is significantly higher than that of PMMA resin(P<0.05). 3. The flexural strength of the group with the mechanical retention form is significantly higher than that of the group without retention form(P<0.05). 4. Comparing with the other groups, the fracture patterns of the group 3 are quite different from the group 1,2,5.

• Macromolecular Research
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• 제16권4호
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• pp.360-366
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• 2008

Poly(dialkoxyphenylene 1,3,4-oxadiazole)s were conveniently synthesized to compare their material properties of solvent solubility, thermal stability and molecular alignment with respect to alkyl chain length and meta/para-phenylene structure. All prepared polymers exhibited good solubility in co-solvents containing various volume levels of chloroform to trifluoroacetic acid. Meta-polymers showed slightly better solubility than para-polymers. All polymers produced were thermally stable up to $320^{\circ}C$. Photoluminescence of polymer films was observed with blue light emission at around 450 nm. X-ray diffraction patterns of all polymers indicated that they were composed of stacked molecular sheets with the same layer-to-layer distance of $3.4\;{\AA}$. However, side chain-to-side chain and main chain-to-main distances within the layers increased with increasing alkyl chain lengths. The meta-polymer chains were separated more than the para-polymer chains.

• 한국염색가공학회지
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• 제29권3호
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• pp.131-138
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• 2017

Most of high performance fabrics for the car racing protective clothing have been developed to have thermal resistance, flame retardant property, impact resistance and anti-frictional properties to protect the racer from the crucial accident. In this study, the meta-aramid fabric, which has inherent flame retardant, was coated with nanoparticles of SiC to enhance the impact resistance and anti-friction properties. Uniform coating of the nanoparticles onto the fabrics was obtained by using tape casting method. As the experimental parameters, size and content of the SiC nanoparticle were varied with the coating conditions of the fabric surface. The effects of the nanoparticle coating on the properties of meta-aramid fabric were examined with various instrumental analyses such as SEM, tensile strength and abrasion test.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제42권
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• pp.41.1-41.11
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• 2020

Background: Orthognathic surgery such as bilateral sagittal split ramus osteotomy (BSSRO) for the treatment of mandibular deformities is one of the most common procedures in maxillofacial operations that may lead to neurosensory disturbance. In this study, we aimed to evaluate the effectiveness of low-level laser therapy (LLLT) on augmenting recovery of neurosensory disturbance of inferior alveolar nerve (IAN) in patients who underwent BSSRO surgery. Methods: A comprehensive literature search was conducted by two independent authors in PubMed, Cochrane Central Register of Controlled Trials (CENTRAL), Scopus, Embase, and Google Scholar electronic databases. Besides, a manual search of all textbooks and relevant articles were conducted. Searches took place in August 2020 and were limited to published and peer-reviewed articles from 2000 to 2020. All analysis was performed using the comprehensive meta-analysis (CMA) and the STATA MP (version:16) software. The weighted mean difference (WMD) using the inverse variance method and the standard mean difference (SMD) was considered for continuous variables. Results: Seventy-four papers were retrieved after removing duplicate studies and finally, eight studies were assessed for qualitative synthesis and five for meta-analysis. Totally, 94 patients were included in the meta-analysis. Based on the meta-analysis, it was shown that LLLT was not effective in a short interval (0 to 48 h) after surgery, but in a period of more than 1 month after surgery, the positive results of treatment can be observed strikingly. Also, LLLT side/group showed no significant difference in some aspects of neurosensory recovery such as thermal sensation compared to the placebo side/group. Conclusions: The meta-analysis of randomized controlled trials revealed that LLLT generally improves IAN sensory disturbance caused by BSSRO. Further high-quality clinical trials with longer follow-up periods and larger sample sizes are recommended.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.81-82
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• 2022

Al and Zn are used to protect the steel structures from corrosion. In the present studies, 15Al-85Zn alloy wires has been used for the deposition of coating by arc thermal spray process. Moreover, this process of coating exhibited severe defects formation, therefore, this coating was post-treated with different concentrations i.e. 0.05, 0.1 and 0.5M sodium hexa meta phosphate (Na6[(PO3)6]: SHMP) to fill to defects of deposited coatings and assessed their corrosion resistance in 3.5 wt.% NaCl solution with exposure periods. After the treatment, the porosity of the coating reduced significantly by formation of composite oxide films onto the coating surface. Initially, 0.5 M SHMP treated coating exhibited highest in total impedance due to significant reduction of porosity but once the exposure periods are extended, the composite oxides are dissolved, thus, total impedance is decreased.

• Composites Research
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• 제26권2호
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• pp.129-134
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• 2013

극저온 환경에 노출되는 구조체의 접착조인트의 경우 피접착물과 접착물 사이에서 열팽창계수 차이로 인해 계면에서 잔류응력이 발생하게 되는데 이에 의해 접착조인트 내부에 미소균열, 층간분리 등의 형태로 파손이 발생할 우려가 있다. 본 연구에서는 높은 비강성, 낮은 열팽창계수의 특성을 지닌 메타 아라미드 섬유를 에폭시 기지재의 보강재로 사용하였다. 표면처리 공정을 간소화하기 위해 전기방사법의 고분자 혼합법(polymer blend method)으로 코어-쉘 구조의 메타 아라미드/에폭시 나노섬유를 제조하였다. 극저온 환경에서 계면특성이 향상된 코어-쉘 구조의 나노섬유를 보강한 에폭시 접착제의 전단물성을 확인하기 위해 환경챔버를 이용하여 $-150^{\circ}C$의 저온에서 단일 겹치기 실험(single lap joint test)을 진행하였다. 또한, DCB(double cantilever beam) 실험을 통해 파괴인성을 측정하였다. 그 결과, 극저온에서 일반 메타 아라미드 나노섬유에 비해 코어-쉘 구조의 메타 아라미드/에폭시 나노섬유를 보강한 접착제 시편이 우수한 계면특성으로 인해 물성이 크게 향상되었음을 확인하였다.

• 한국세라믹학회지
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• 제17권4호
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• pp.213-216
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• 1980

A glass-ceramics material of composition %SiO_2$: 38.50, $Al_2O_3$: 26.00, $Na_2O$: 18.00, CaO: 6.00, MgO: 4.00, $TiO_2$: 7.50 was strengthened by coating a series of glazes$(SiO_2-B_2O_3-Al_2O_3-CaO-PbO-Na_2O-)$, which has lower thermal expansion coefficient than that of the glass-ceramics. The thermal expansion coefficient of the glazes ranges $80~90{\times}10^{-7}$cm/cm/$^{\circ}C$, whereas that of the glass-ceramics is $115{\times}10^{-7}$cm/cm/$^{\circ}C$. The glass-ceramics was identified to be composed of nepheline, carnegieite low form, and meta sodium silicate crystal by X-ray diffraction phase analysis. The glaze, having lower melting point and appropriate thermal expansion coefficient, was tried to be stable and good at secondary heat treatment.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.188-188
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• 2011

Recently, scaling down of ULSI (Ultra Large Scale Integration) circuit of CMOS (Complementary Meta Oxide Semiconductor) based electronic devices, the electronic devices, become much faster and smaller size that are promising property of semiconductor market. However, very narrow interconnect line width has some disadvantages. Deposition of conformal and thin barrier is not easy. And metallization process needs deposition of diffusion barrier and glue layer for EP/ELP deposition. Thus, there is not enough space for copper filling process. In order to get over these negative effects, simple process of copper metallization is important. In this study, Cu-V alloy layer was deposited using of DC/RF magnetron sputter deposition system. Cu-V alloy film was deposited on the plane SiO2/Si bi-layer substrate with smooth surface. Cu-V film's thickness was about 50 nm. Cu-V alloy film deposited at $150^{\circ}C$. XRD, AFM, Hall measurement system, and AES were used to analyze this work. For the barrier formation, annealing temperature was 300, 400, $500^{\circ}C$ (1 hour). Barrier thermal stability was tested by I-V(leakage current) and XRD analysis after 300, 500, $700^{\circ}C$ (12 hour) annealing. With this research, over $500^{\circ}C$ annealed barrier has large leakage current. However vanadium-based diffusion barrier annealed at $400^{\circ}C$ has good thermal stability. Therefore thermal stability of vanadium-based diffusion barrier is desirable for copper interconnection.

• 한국추진공학회지
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• 제21권1호
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• pp.1-7
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• 2017

항공기 엔진 배기노즐 표면으로부터 적외선 방사를 낮추기 위한 연구의 일환으로 스테인리스 스틸 표면을 구리입자/메타 아라미드 수지 복합재료로 도포하여 $320^{\circ}C$에서 적외선 방사율을 측정하였다. 일반적인 충전제 입자 바인더 합성수지의 경우 $300^{\circ}C$이전에서 대부분 열분해를 일으키지만 메타 아라미드 수지는 $320^{\circ}C$에서도 열안정성을 보여 구리입자 분산 내열성 매트릭스 수지로 적합한 것으로 나타났다. 본 연구에서는 첨가한 구리입자 함량은 부피기준으로 0 ~ 70% 까지 변화시켰다. 구리입자/메타아라미드 복합재료 수지로 도포된 시편은 $320^{\circ}C$에서 적외선 방사율 측정 실험 후에 접착력이 우수하였다. 그리고 구리입자 함량이 부피 기준으로 50%인 구리입자/메타 아라미드 수지를 도포함으로써 시편의 $320^{\circ}C$ 적외선 방사율을 0.6 까지 낮출 수 있었다.