• Journal of Periodontal and Implant Science
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• 제42권3호
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• pp.81-87
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• 2012

Purpose: The characteristics of oxidized titanium (Ti) surfaces varied according to treatment conditions such as duration time and temperature. Thermal oxidation can change Ti surface characteristics, which affect many cellular responses such as cell adhesion, proliferation, and differentiation. Thus, this study was conducted to evaluate the surface characteristics and cell response of thermally treated Ti surfaces. Methods: The samples were divided into 4 groups. Control: machined smooth titanium (Ti-S) was untreated. Group I: Ti-S was treated in a furnace at $300^{\circ}C$ for 30 minutes. Group II: Ti-S was treated at $500^{\circ}C$ for 30 minutes. Group III: Ti-S was treated at $750^{\circ}C$ for 30 minutes. A scanning electron microscope, atomic force microscope, and X-ray diffraction were used to assess surface characteristics and chemical composition. The water contact angle and surface energy were measured to assess physical properties. Results: The titanium dioxide ($TiO_2$) thickness increased as the treatment temperature increased. Additional peaks belonging to rutile $TiO_2$ were only found in group III. The contact angle in group III was significantly lower than any of the other groups. The surface energy significantly increased as the treatment temperature increased, especially in group III. In the 3-(4,5-Dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide assay, after 24 hours of incubation, the assessment of cell viability showed that the optical density of the control had a higher tendency than any other group, but there was no significant difference. However, the alkaline phosphatase activity increased as the temperature increased, especially in group III. Conclusions: Consequently, the surface characteristics and biocompatibility increased as the temperature increased. This indicates that surface modification by thermal treatment could be another useful method for medical and dental implants.

• 대한화학회지
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• 제57권4호
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• pp.432-438
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• 2013

기초 화학 실험에서 쉽게 만들고 운용할 수 있는 접촉각 측정기를 구성했다. LED 손전등과 시료 거치대, 디지털 카메라를 광학보드에 고정했고, 시료부는 양쪽에 구멍이 뚫린 암실 상자로 덮었다. 공개된 영상분석 프로그램(ImageJ)과 플러그인(Drop_analysis)을 이용해서 고체 표면 위에 형성된 액체 방울의 사진으로부터 접촉각을 측정했다. 구성된 측정기와 해석 프로그램을 이용해 여러 액체와 다양한 표면에서의 접촉각을 측정해 측정기의 성능을 확인했다. 측정된 $H_2O$와 $CH_2I_2$ 접촉각으로부터 결정된 고체의 표면에너지들은 알려진 값들과 대체로 일치하며 표면의 특성과 개질, 비극성 및 극성 기여도 등을 충실히 보여준다. 이 논문에 소개된 수제 접촉각 측정기와 측정법을 활용해 기초 화학을 배우는 학생들이 젖음성, 친수성, 발수성 등 표면 특성들과 분자 간 상호작용을 이해하고 관련된 힘의 평형, 광학, 수식의 전개 등을 경험할 수 있다.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.75-87
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• 2001

Three different kinds of substrate used in this study : bare Cu substrate, Ni-P/Cu substrate with a Ni-P layer thickness of $5\mu\textrm{m},$ and Au/Ni-P/Cu substrate with the Ni-P and Au layers of $0.15\mu\textrm{m}$ and $5\mu\textrm{m}$ thickness respectively. The wettability of various Sn-base solders was affected by the substrate metal finish used, i.e., nickel, gold and copper. On the Au/Ni-F/Cu substrate, Sn-base solders wet better than any of the other substrate metal finishes tested. The interfacial reaction between various substrate and Sn-base solder was investigated at $70^{\circ}C,$ $100^{\circ}C,$ $120^{\circ}C,$ $150^{\circ}C,$ $170^{\circ}C$ and $200^{\circ}C$ for reaction times ranging from 0 day to 60 day. Intermetallic phases was formed along a Sn-base solder/ various substrate interface during solid-state aging. The apparent activation energy for growth of Sn-Ag/Cu, Sn-Ag-Bi/Cu, and Sn-Bi/Cu couples were 65.4, 88.6, and 127.9 Kj/mol, respectively. After isothermal aging, the fracture surface shoved various characteristics depending on aging temperature and time, and the types of BGA pad.

• 마이크로전자및패키징학회지
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• 제3권1호
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• pp.11-24
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• 1996

부분압이 다른 여러 가지 반응성 가스분위기하에서 이른곤 이온을 이용하여 PC, PET PMMA 그리고 PTFE 폴리머 표면의 삼차 증류수에대한 진수성을 증대하였다. 폴리머 표면의 친수성의 변화는 여러 가지 반응성 가스 분위기하에서 아르곤 이온의 조사량을 1014 부터 1x1017cm2까지 변화하면서 조사하였다. 접촉감은 아르곤 이온이 조사되는 폴리머 표면 근처에 유입된 가스의 방응성(O2>N2>H2)에 따라 많이 감소하였다, 폴리머 표면에 형성된 친수성기는 XPS Cls, Ols, 그리고 Nls 스펙트럼을 분석하여 확인하였다. 표면 개질된 PC와 PTFE에 대한 Al 금속의 접착력 증대를 Scotch tape와 인장실험을 통하여 확인하였다. 접착 력 증가는 표면 에너지 중 polar force의 증가에 의한 것으로 입증되었다. 에너지를 가진 아 르곤 입자 폴리머 체인 그리고 반응성 가스 사이의 반응기구는 2단계 모델로 설명가능하였 는데 그 기구는 첫 번째 이온의 조사에 의한 불안정한 폴리머 체인의 형성과 두 번째 단계 로 이렇게 형성된 폴리머 체인과 반응성 가스들 사이의 화학반응으로 이루어진다. 질화아루 미늄의 표면을 산소분위기하에서 아르곤 빔을 조사하여 표면개질한후 AlON층이 새롭게 형 성된 것을 XPS를 이용하여 확인할수 있었다. 개질된 질화알루미늄과 구리금속 박막간의 접 착력을 scratch 실험을 통하여 조사하였다.

• 마이크로전자및패키징학회지
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• 제25권1호
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• pp.11-15
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• 2018

본 논문에서는 UV 나노임프린트 공정으로 제작한 나노 콘 형태의 구조물 위에 은 나노 입자를 증착하여 광증폭용 구조 형태를 제작하고자 하였다. 은 나노 입자의 증착은 하부 기판 표면의 젖음 특성에 따른 액적의 증발 거동을 이용하였으며, 기판 하부 열에너지의 차이에 따라서 액적 중심부부터 가장자리까지 증착 형태가 변화함을 확인하였다. 제작한 구조 형태와 유사한 구조를 시간영역 유한차분(FDTD)법을 통해 광 특성을 예측하여, 최종적으로 제작한 구조의 은나노 입자 부근에 에너지가 집중되는 결과를 확인하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.301.1-301.1
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• 2016

We report an ultraclean, cost-effective, and easily scalable method of transferring and patterning large-area graphene using pressure sensitive adhesive films (PSAFs) at room temperature. This simple transfer is enabled by the difference in wettability and adhesion energy of graphene with respect to PSAF and a target substrate. The PSAF transferred graphene is found to be free from residues, and shows excellent charge carrier mobility as high as ${\sim}17,700cm^2/V{\cdot}s$ with less doping compared to the graphene transferred by thermal release tape (TRT) or poly(methyl methacrylate) (PMMA) as well as good uniformity over large areas. In addition, the sheet resistance of graphene transferred by recycled PSAF does not change considerably up to 4 times, which would be advantageous for more cost-effective and environmentally friendly production of large-area graphene films for practical applications.

• 한국해양공학회지
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• 제15권3호
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• pp.49-57
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• 2001

One of the most important considerations to braze Cu-Al dissimilar materials is control of brittle metallic compound which makes it difficult to obtain a sound brazed joint. Nowdays, several attempts were made to control the metallic compound. But effective method for controlling metallic compound was not established. In this point of view, commercially pure aluminum and copper were used as base metal and Al-Si-X and Zn-Al-X alloy systems were developed as filler metal. Brazing was carried out to find optimum conditions for Cu-Al dissimilar joint. The results obtained in this study were summarized as follows: 1) The joint brazed by Al-Si-X filler metal showed good brazeability and mechanical properties. The tensile strength of the joint brazed over solidus temperature was more than 90% of Al base metal. Especially, the joint brazed at liquidus temperature was fractured in the Al base metal. 2) Fluorides fluxes(a mixture of potassium fluoro-aluminates) were used to improve surface cleanliness of base metal and wettability of Al-Si-X filler metal. It was melted at the temperature about 1$0^{\circ}C$ lower than that of the filler metal, and made appropriate brazing environment. Therefore, it could be a proper selection as flux.

• 한국염색가공학회지
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• 제4권1호
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• pp.1-9
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• 1992

In order to study on the surface modification of the poly(ethylene Terephthalate)(PET) fabrics, low temperature plasma$(O_2)$ has been irradiated on the PET fabrics in various conditions. Experiments were carried out at pressure ranging from 0.5 tort to 3 tort. The properties of PET fabrics treated with low temperature plasma($(O_2)$, such as bathochromic, wettability, antistatic property were measured. Etching ratio was increased as the pressure and the output of discharge increased. When its were put on the cathode, the most efficient effect of etching according to the position of sample between anode and cathode was obtained. The bathochromic effect has more or less improved as pressure was getting higth in case of dyed fabrics treated with only low temperature plasma$(O_2)$ . And when it was treated with the low refractive index resin, the bathochromic of dyed fabrics treated with low temperature plasma$(O_2)$ was better than that of the dyed fabrics untreated.

• Composites Research
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• 제26권5호
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• pp.303-308
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• 2013

탄소섬유(CF) 강화 폴리프로필렌(PP) 복합재료의 수요는 증가되고 있다. 본 연구에서는 재활용 횟수에 따라 변화되는 복합재료의 물성 변화를 관찰하였다. CF 함량을 20% 함량으로 조성한 복합재료에 대해서 재활용 횟수에 따른 기계적 물성 평가를 진행하였다. 인장, 굴곡, Izod 동적 피로 실험에 따른 영향을 확인하였다. CF/PP 복합재료의 계면 물성을 평가하기 위해 젖음성 평가와 파단면을 FE-SEM으로 확인하였다. 재활용 횟수에 따라 섬유와 기지는 변화된다. CF/PP 복합재료는 재활용 할수록 섬유와 기지간의 계면에 열 데미지와 분쇄 과정에 의한 결합력 감소가 확인하였다.

• Journal of Electrochemical Science and Technology
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• 제5권2호
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• pp.58-64
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• 2014

The surface of an ordered mesoporous silica (OMS) was functionalized using 1H,1H,2H,2H-perfluorooctyltrimethoxysilane at $20^{\circ}C$ and $60^{\circ}C$. It was shown that only elevated temperature allows lyophobic properties on the walls of OMS, eventually preventing pore flooding with nonaqueous electrolytes. The functionalized OMSs (OMS-F) were characterized with various techniques: wettability test, $N_2$ sorption measurement, high-resolution transmission electron microscopy (HR-TEM). Cathodes of $10mg/cm^2$ loading were prepared with a commercial Pt/C catalyst and polyvinylidene fluoride (PVDF, 2.5 wt.%) binder using a typical doctor blade method on a commercial gas diffusion layer (GDL) in the presence or in the absence of OMS-F additives. Subsequent discharge-charge curves were taken in a 1M LiTFSI-TEGDME electrolyte at 60oC in pure oxygen atmosphere. It was found that the discharge capacity was significantly affected by OMS-F: 5 wt.% of additive extended discharge capacity by a factor 1.5. On the other hand, a similar OMS material but synthesized at $20^{\circ}C$ did not show lyophobic properties and deteriorated cathode capacity.