• 공업화학
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• 제17권6호
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• pp.586-590
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• 2006

전기활성 고분자로서 이온성고분자-금속복합체(Ionic Polymer metal Composites, IPMC)는 화학적 환원방법으로 비교적 쉽게 제조하여 낮은 구동전압에서도 큰 변위를 낼 수 있는 유연성을 지니는 스마트 소재(soft smart material) 중의 하나이다. 제조 시의 화학적 환원방법은 용액 내에서 반응시킴으로써 결과적으로 형성되는 다공성 고분자 막의 표면의 거칠기 때문에 구동체로서의 IPMC의 동작특성에 결함을 줄 수 있다. 따라서 본 연구에서는 IPMC의 표면의 거칠기에 대한 구동 특성을 비교하고 표면 조도를 향상시키는 방안으로 표면 이온빔 보조 증착법으로 표면을 개질하였다. 이러한 표면 개질 효과로 인해 IPMC 전극의 표면 저항을 낮추고 반응 속도를 증가시킬 수 있었고, 표면 조도, 모폴로지, 구동력 등을 측정하여 향상된 구동 현상을 나타내는 제조방법에 대한 연구를 하였다.

• 전기의세계
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• 제30권3호
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• pp.172-176
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• 1981

The reduction in the breakdown field strength due to electrode surface roughness was calculated by applying the streamer breakdown criterion and the surface roughness factor, and measurements of static breakdown voltage for a gap with an artificial protrusion were made under the uniform field at pressures up to 4 bar in pressurized $SF_{6}$. The effect of polarity of highly stressed electrode on the breakdown field strength was also investigated. The measurements have shown that the measured breakdown levels for a protrusion located on the cathode agree with those calculated and the values measured with an identical anode protrusion are substantially higher and more scattered. This may be explained if it assumed that a high rate of production of initiatory electrons is maintained at the tip of a cathode protrusion by field emission. In practical point of view, the breakdown levels in pressurized $SF_{6}$ can be bereliably estimated from the values calculated.

• 한국지반공학회논문집
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• 제39권6호
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• pp.21-30
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• 2023

현장타설말뚝의 연암 근입부의 단위주면마찰력을 산정하는 방법 중 암반 벽면거칠기에 의한 산정 방법이 있다. 현장타설말뚝의 굴착 시공 시 암반 굴착공에 거칠기 장치를 설치하고 벽면 거칠기 모양을 측정하고 그 결과를 이용하여 주면마찰력을 산정하는 것이다. 본 연구에서는 암반벽면의 거칠기를 직접 측정한 결과와 하중전이 시험결과를 비교분석하여 거칠기시험에 의한 단위주면마찰력을 말뚝의 발생 변위에 대응하는 단위 주면마찰력으로 변환할 수 있도록 저감계수 R_f = -0.14n + 1.48(여기서, n은 하중전이시험에서 도출된 발생변위 δ를 말뚝직경 D로 나눈 변위비)을 제안하였다.

• KSTLE International Journal
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• 제1권1호
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• pp.12-20
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• 2000

Nano-wear and friction of carbon overcoated laser-textured and mechanically-textured computer hard disk were characterised after contact start/stop (CSS) wear test. Various analytical and mechanical testing techniques were employed to study the changes in topography, roughness, chemical elements, mechanical properties and friction characteristics of the coating arising from the contact start/stop wear test These techniques include: the atomic force microscopy (AFM), the continuous nano-indentation test, the nano-scratch test, the time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and the auger electron spectroscopy (AES). It was shown that the surface roughness of the laser-textured (LT) bump and mechanically textured (MT) Bone was reduced approximately am and 7nm, respectively, after the CSS wear test. The elastic modulus and hardness values increased after the CSS test, indicating straining hardening of the top coating layer, A critical load was also identified fer adhesion failure between the magnetic layer and the Ni-P layer, The TOF-SIMS analysis also revealed some reduction in the intensity of C and $C_2$$F_59$, confirming the wear of lubricant elements on the coating surface.

• 한국산학기술학회논문지
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• 제16권11호
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• pp.7878-7884
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• 2015

해수의 접촉이 많은 금속 임펠러는 해수의 염분에 의해 부식이 되므로 탄소섬유로 제작된 임펠러를 사용한 해수펌프가 개발되었다. 해수펌프의 임펠러와 와류실의 최적설계를 수치해석을 통해 수행하였고 관련인자(임펠러 두께, 표면 거칠기)의 영향을 평가하였다. 임펠러의 두께는 무게 때문에 재료에 따라 제한된다. 탄소섬유를 사용한 임펠러는 경량이므로 최대효율을 나타내는 임펠러 두께를 사용할 수 있다. 표면 거칠기의 경우 같은 운전 조건에서 펌프의 효율에 7 % 범위에서 영향을 주는 것을 확인하였다.

• 한국광학회지
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• 제9권2호
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• pp.63-69
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• 1998

수직 공진 표면광 레이저에서 분산 브라그 반사경의 광 산란 손실을 자세히 분석하기 위하여, 광산란 실험을 수행하고 산란효과를 고려한 투과 행렬 방법을 통하여 표면 거칠기에 대한 정보를 추출하였다. 산란실험에는 수직 공진 표면광 레이저 제작에 사용된 다양한 종류의 웨이퍼가 이용되었다. 거울각 근처의 산란광 세기를 추정하기 위해서 fractal 표면을 가정하였다. 분석에 사용된 변형된 투과 행렬 방법은 각 경계 면에서 산란 손실을 고려하면서 반사율을 효과적이고 쉽게 계산할 수 있게 하였다. 실험결과, 표면 거칠기는 $4{\AA}$ 에서 $10{\AA}$로 나타났고, 산란에 따른 반사율 감소는 거칠기가 $10{\AA}$ 경우에 0.26%에 해당하였다.

• Tribology and Lubricants
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• 제35권2호
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• pp.94-98
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• 2019

The riblet structure like shark skin has been widely studied owing to its drag reduction and anti-fouling properties. In this study we simulated the wettability of an oil droplet on a riblet surface. We developed a numerical analysis method using the Wenzel equation and Cassie-Baxter equation that can estimate the contact angle with a penetrated depth of the droplet on rough surfaces. Riblet surfaces with nine scales composed of five hemi-elliptical ribs are generated numerically. The variation of contact angles with fractional depth of penetration for the generated riblet surfaces with and without coatings is demonstrated in the condition of solid-air-oil and solid-water-oil interfaces. The contact angle for the uncoated surface decreases with increasing fractional depth of penetration more drastically than that for the coated surface. For the effect of surface roughness on the contact angle of the droplet, the oleophilic surface gives lower contact angle when the surface is rougher, whereas the oleoophobic surface gives higher contact angle with higher roughness To verify the analysis results, the wetting angle was measured in the solid-air-oil interface and solid-water-oil interface for the shark-skin template and shark-skin replica. The effects of teflon coating were also evaluated. It is shown that the simulation results cover the experimental ones.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.225-226
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• 2012

전기방사법으로 형성한 마이크로 크기의 실리카($SiO_2$) 코팅층 위에 광환원법(photo-reduction mothod)를 이용하여 나노 크기의 금속 나노입자를 형성하여 마이크로-나노 계층구조(hierarchical structure)의 코팅층을 형성하였다. 자외선(UV선) 조사강도 및 조사시간의 변화에 따른 미세구조 및 표면 평활도지수(roughness factor) 변화 거동을 관찰하였고, 이 코팅층에 불소화 처리를 하여 초소수성 표면을 형성하였다.

• 한국재료학회지
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• 제23권1호
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• pp.53-58
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• 2013

Superhydrophobic $SiO_2$ layers with a micro-nano hierarchical surface structure were prepared. $SiO_2$ layers deposited via an electrospray method combined with a sol-gel chemical route were rough on the microscale. Au particles were decorated on the surface of the microscale-rough $SiO_2$ layers by use of the photo-reduction process with different intensities ($0.11-1.9mW/cm^2$) and illumination times (60-240 sec) of ultraviolet light. With the aid of nanoscale Au nanoparticles, this consequently resulted in a micro-nano hierarchical surface structure. Subsequent fluorination treatment with a solution containing trichloro(1H,2H,2H,2H-perfluorooctyl)silane fluorinated the hierarchical $SiO_2$ layers. The change in surface roughness factor was in good agreement with that observed for the water contact angle, where the surface roughness factor developed as a measure needed to evaluate the degree of surface roughness. The resulting $SiO_2$ layers revealed excellent repellency toward various liquid droplets with different surface tensions ranging from 46 to 72.3 mN/m. Especially, the micro-nano hierarchical surface created at an illumination intensity of $0.11mW/cm^2$ and illumination time of 60 sec showed the largest water contact angle of $170^{\circ}$. Based on the Cassie-Baxter and Young-Dupre equations, the surface fraction and work of adhesion for the micronano hierarchical $SiO_2$ layers were evaluated. The work of adhesion was estimated to be less than $3{\times}10^{-3}N/m$ for all the liquid droplets. This exceptionally small work of adhesion is likely to be responsible for the strong repellency of the liquids to the micro-nano hierarchical $SiO_2$ layers.

• 한국전기전자재료학회논문지
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• 제20권12호
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• pp.1027-1033
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• 2007

In this research, the polishing pad for W CMP has been analyzed to understand stabilization of polishing performance. For stabilization of process, the polishing pad condition is one of important factors. The polishing pad plays a key role in polishing process, because it contact with reacted surface of wafer[1]. The physical property of pad surface is ruled by conditioning tool which makes roughness and profile of pad surface. Pad surface affects on polishing performance such as RR(Removal Rate) and uniformity in CMP. The stabilized pad surface has stable roughness. And its surface has high level of wettability which can increase the probability of abrasive adhesion on pad. The result of this research is that the reduction of break-in and dummy polishing process were achieved by artificial machining to make stable pad surface. In this research, urethane polishing pad which is named IC pad(Nitta-Haas Inc.) and has micro pore structure, is studied. Because, this type of pad is the most conventional type.