• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2014.11a
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• pp.279-279
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• 2014

젖음각 80도 이상의 금속분리판 표면을 상압 플라즈마 처리하여 젖음각 10~40도를 갖는 표면으로 개질하였다. 친수성 처리 후 항온항습 상태에서 젖음각 변화를 관찰하였다. 또한 표면 및 부식 특성을 평가하였다.

• Proceedings of the Korean Vacuum Society Conference
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• 2008.02a
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• pp.165-165
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• 2008

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.327-327
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• 2011

DLC 필름은 바이오 적합성, 특히 생체 적합성이 뛰어나기 때문에 바이오 코팅분야에서 널리 이용된다. 많은 연구 결과에 의하면 세포와 장기 등이 바이오 재료 표면에 적절히 접합할 수 있도록, 재료 표면을 산소나 질소를 이용하여 플라즈마 처리로 초친수성 표면으로 개질하고 있다. 하지만, 시간이 지남에 따라서 친수성 표면은 점차 재료의 표면 처리 전의 성질인 소수성을 회복하게 된다. D실제 생체에 적용하기 위해서 이러한 시효 효과에 대한 정확한 평가가 이루어져야 한다. 따라서 산소와 질소 플라즈마 처리 후의 친수성 성질이 소수성 성질로 변해가는 거동을 조사하는게 중요하다. 13.56 MHz의 plasma assisted chemical vapor deposition (PACVD) 법을 이용하여 DLC와 Si-DLC를 500 ${\mu}m$ 두께의 P-type 실리콘(100) 기판에 증착하였다. 박막 증착 과정에 사용한 기체는 벤젠과 희석된 silane이 사용되었다(SiH4/H2=10:90). 박막 증착은 -400 V의 바이어스 전압을 인가하였으며, 이때 증착 압력은 1.33Pa으로 일정하게 유지하여, 두께 $0.55{\pm}0.01{\mu}m$로 증착하였다. X-ray Photoelectron Spectroscopy (XPS) 법을 이용하여 실리콘 함량을 측정하였으며, 증착 된 Si-DLC의 실리콘 함량은 0~4.88 at. %였다. 이후에 질소와 산소 플라즈마를 이용하여 챔버 압력을 1.33 Pa로 유지하여, -400 V의 바이어스 전압을 인가하여 10분간 표면 처리를 하였다. 표면 처리된 DLC와 Si-DLC 표면 위에서의 물방울(water droplet)의 젖음각을 20일간 측정하였다. 플라즈마 표면 처리 된 모든 시편에서 초기 젖음각은 $10{\sim}20^{\circ}$의 친수성 성질을 보였지만, 점차 젖음각이 상승하여 산소 플라즈마 처리 된 Si-DLC를 제외하고는 5일이 지나면서 거의 소수성 표면으로 회복되었다. 산소 플라즈마 처리 된 Si-DLC의 경우, 젖음 각 측정 기간(20일) 동안 $15^{\circ}$ 미만의 친수성 성질을 유지하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.298-302
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• 2008

This study was carried out to evaluate brazing characteristics of the braze joint between superhard alloy particles and carbon steel. Two types of insert metals that made by mechanical alloying process were selected for this study. One is composed of Cu, Zn and Ag(MIM-1) and the other one is composed of Cu, Zn, Ag and Cd.(MIM-2) The chemical compositions of these insert metals were similar to AWS BAg-20 and BAg-2a system. And the commercial insert metals(CIM-1, CIM-2) were also evaluated for the comparative study. The characterization of the insert metals were conducted by wettability tests, shear tensile test and microstructural analyses. The results indicated that wettability tests displayed that MIM-1 and CIM-1 insert metals had the larger wetting angle than MIM-2 and CIM-2 and the wetting angle of the MIM-1 showed higher value than that of CIM-1. However these values are less than $25^{\circ}$ that is recommended for standard value for usual insert metals. The highest value of shear tensile tests was obtained from the brazed joint that made by MIN-1 and the value was $2.29{\times}10^2MPa$. This value is appeared to be higher or same as the commercial insert metals. The microstructures of the inserts metals were composed of Cu-rich proeutectic structure for matrix and Ag-rich eutectic structure. The braze joint between superhard alloy particles and carbon steel produced by the MIM-1(Ag-Cu-Zn) system showed sound joint showing stable microstructures. However there was also some porosities at the interface.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.3
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• pp.25-30
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• 2015

SAC-coated Cu specimens were fabricated by novel pad finish process using a phenomenon that metal nanoparticles less than 20 nm in diameter melted at a temperature lower than the melting point of bulk metal, and their wettabilities were evaluated. The thickness of SAC305 layer coated at low temperature of $160^{\circ}C$ using SAC305 ink was extremely thin as the level of several nanometers. It was analyzed by Auger electron spectroscopy that $Cu_6Sn_5$ intermetallic layer with a thickness of 10~100 nm and $Cu_3Sn$ intermetallic layer with a thickness of 50~150 nm were sequentially formed under the SAC305 coating layer. The thickness of formed intermetallic layers was thicker in electroplated Cu than rolled Cu, which attributed to improved surface roughness in the electroplated Cu. The improved surface roughness induces the contact, melting, and reaction of a larger number of SAC305 nanoparticles per the unit area of Cu specimen. In the wetting angle test using SAC305 solder balls, the Cu coated with SAC305 through the low temperature process presented evidently low wetting angles than those in non-coated Cu, indicating that only a few nanometer-thick SAC305 coating layer on Cu could also cause the enhancement of wettability.

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.11a
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• pp.195-195
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• 2003

PDP, FED 등의 디스플레이와 각종 IC 칩부품에 적용 가능한 저융점 유리 프릿 중에서 환경규제가 이루어지고 있는 납성분이 포함되어 있지 않은, Bi계 유리 프릿의 열적 거동 연구를 행하였다. 열처리 온도에 따른 열거동에 따라 프릿의 소성온도 및 미세구조가 결정되므로, 열처리 온도에 따른 유리 프릿의 젖음각을 측정하였고, DTA와 TMA를 통해 유리전이온도, 연화점, 열팽창계수 변화 경향성을 관찰하였다. 본 연구에서 제조된 유리는 조성에 따라 전이온도가 390-50$0^{\circ}C$, 연화점이 400-55$0^{\circ}C$, 열팽창계수가 65-120$\times$10-7/$^{\circ}C$ 범위를 나타내었으며, 고온현미경 측정 결과 Pb-계 유리와 비교시 유사한 열거동을 나타내었다.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.335-341
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• 2019

Purpose: Chemically strong-acids (HF and $HCl/H_2SO_4$) dual etching implant surfaces have higher strengths of osseointegration than machined implant surfaces. However, the dual acid treatment deteriorates the physical properties of the titanium by weakening the fatigue resistance of the implant and causing microcracks. The removal torque comparison between the dual-acid etched (hydrochloric acid, sulfuric acid, HS) and single-acid etched implants (hydrochloric acid, H) could reveal the efficiency of implant surface acid treatment. Materials and methods: Nine $3.75{\times}4mm$ dual-acid etched SLA implants and nine single-acid etched SLA implants were inserted into New Zealand rabbit tibias. After 10 days, removal torque, roughness, and wetting angle were measured. Results: Mean removal torque values were as follows: Mean removal torque were 9.94 Ncm for HS group and 9.96 Ncm for H group (P=.995). Mean surface roughness value were $0.93{\mu}m$ for HS group and $0.84{\mu}m$ for H group (P=.170). Root mean square roughness (RSq) values were $1.21{\mu}m$ for HS group and $1.08{\mu}m$ for H group (P=.294), and mean wetting angle values were $99^{\circ}$ for HS group and $98^{\circ}$ for H group (P=.829). Statistical analysis showed no significant difference between the removal torques, roughness, or wetting angles of the two groups. Conclusion: In this experiment, we found no significant difference in removal torque, roughness, or wetting angle between dual-acid etched and single-acid etched implants.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.05a
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• pp.25-33
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• 2002

Effect of surface topography on the water wetting nature and micro/nano tribological characteristics of Si-wafer and PTFE was experimentally studied. The ion beam treatment was performed with a hollow cathode ion gun in different argon don dose conditions in a vacuum chamber to change the surface topography, Micro/nano tribological characteristics, water wetting angles and roughness were measured with a micro tribo tester, SPM (scanning prove microscope), contact anglemeter and profilometer, respectively. Results showed that surface roughness increased with the argon ion dose. The water wetting angle of tile ion beam treated samples also increased with the ion dose. Results also showed that micro-adhesion and micro-friction depend on the wetting characteristics of the PTFE samples. However, nano-triboloSical characteristics showed little dependence on the wetting angles. The water wetting characteristics of modified PTFE samples were discussed in terms of the surface topographic characteristics.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.328-334
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• 2019

Purpose: The aim of this study was to confirm if Laser-treated implants were soaked in 0.9% NaCl solution for 2 weeks could increase the surface hydrophilicity, and the Remoal Torque of each implant that inserted in rabbit tibia for initial healing period of 10 days. Materials and methods: Twenty machined titanium surface screws were produced with a diameter 3 mm, length 8 mm. Ten screws had their surface treated with a laser only (laser treated group), and the other 10 were soaked in saline for 2 weeks after surface treatment with a laser (laser treated + saline soaked group). Implants were inserted in rabbit tibia (ten adult New Zealand white rabbits), and the RTQ of each implant was measured after 10 days. The wettability among implants was compared by measuring the contact angle. Surface composition and surface topography were analyzed. Results: After 10 days, the laser treat + soaking group implants had a significantly higher mean RTQ than the laser treated implants (P = .002, < .05). There were no significant morphological differences between groups, and no remarkable differences were found between the two groups in the SEM analysis. Conclusion: Saline soaking implants is expected to produce excellent RTQ and surface analysis results.

• Polymer(Korea)
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• v.34 no.1
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• pp.52-57
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• 2010

The low viscous epoxy resin(bisphenol F) with carboxylic acid as the reductants was introduced for high performance and reliability in the ACA with a low melting point alloy filler system. The curing characteristics of the epoxy resin and temperature dependant viscosity characteristic of epoxy resin at the melting temperature of LMPA were investigated by dynamic mode of differential scanning calorimetry (DSC) and rheometer, respectively. Based on these thermo-rheological characteristics of epoxy resin and LMPA, the optimum process system was designed. In order to remove the oxide layer on the surface of LMPA particle, three different types of carboxyl acid-based reductant were added to the epoxy resin. The wetting angles were about $18^{\circ}$ for carboxypropyldisilioxane, and $20.3^{\circ}$ for the carboxy-2-methylethylsiloxane, respectively.