• 한국소성가공학회:학술대회논문집
• /
• 한국소성가공학회 2005년도 추계학술대회 논문집
• /
• pp.113-117
• /
• 2005

In the modern days, a galvannealed sheet steel (GA) instead of a cold rolled steel sheet has been widely used as an alternative to extend the life of automotive body. Accordingly, the mechanical properties of GA for automobiles were taken into account and studied by comparing with the temperature variation on annealing in this study. To clarify the effect of surface features in the mechanical and frictional properties of GA, the several tests such as nanoindentation, victors hardness and nano scratch test were executed. The developed neural networks apply also to obtain reliable mechanical properties of the thin films. Load-displacement curve was computed by the analysis procedure and compared with experimental results. The frictional characteristics of coating layers in GA were verified though nano scratch test in this study. The friction coefficient of coating layers on the surface was obtained from the nano scratch. The variation of friction coefficient versus velocity and pressure was taken into consideration in this paper.

• 마이크로전자및패키징학회지
• /
• 제29권1호
• /
• pp.61-66
• /
• 2022

이 연구는 원자층 증착(Atomic Layer Deposition, ALD) 기술을 사용하여 나노미터 크기의 금속 촉매 물질을 연료극 층에 코팅하여 표면적을 늘리고 촉매의 효과를 극대화시키기 위한 연구이다. ALD 공정은 기판 위에 원자 수준에서 잘 제어된 두께를 갖는 균일한 막을 제조하는 것으로 알려져 있다. 우리는 고체산화물 연료전지의 연료극 물질로 가장 널리 알려진 Ni/YSZ 위에 금속(Ni)을 코팅하여 성능을 측정하였다. ALD 코팅은 3 nm 이상의 코팅에서 전지 성능의 감소를 보이기 시작했다

• Corrosion Science and Technology
• /
• 제23권1호
• /
• pp.72-81
• /
• 2024

The Ti-6Al-4V alloy is widely used as an implant material due to its higher fatigue strength and strengthto-weight ratio compared to pure titanium, excellent corrosion resistance, and bone-like properties that promote osseointegration. For rapid osseointegration, the adhesion between the titanium surface and cellular biomolecules is crucial because adhesion, morphology, function, and proliferation are influenced by surface characteristics. Polymeric peptides and similar coating technologies have limited effectiveness, prompting a demand for alternative materials. There is growing interest in 2D nanomaterials, such as MoS₂, for good corrosion resistance and antibacterial, and bioactive properties. However, to coat MoS₂ thin films onto titanium, typically a low-temperature hydrothermal synthesis method is required, resulting in the synthesis of films with a toxic 1T@2H crystalline structure. In this study, through high-temperature annealing, we transformed them into a non-toxic 2H structure. The implant coating technique proposed in this study has good corrosion resistance and biocompatibility, and antibacterial properties.

• Transactions on Electrical and Electronic Materials
• /
• 제6권4호
• /
• pp.140-143
• /
• 2005

Carbon Nanotube(CNTs) counter electrode is a promising alternative to Platinum counter electrode for dye sensitized solar cells (DSSCs). In this study, CNT counter electrodes having different visible light transmittance were prepared on fluorine-doped tin oxide (FTO) glass surface by spray coating method. Microstructural images show that there are CNT-tangled region coated on FTO glass counter electrodes. Using such CNT counter electrodes and screen printed $TiO_2$ electrodes, DSSCs were assembled and its I-V characteristics have been studied and compared. Light energy conversion efficiency of DSSCs increased with decreasing in light transmittance of CNT counter electrode. Efficiency of DSSCs having CNT counter electrode is compatible to that of Pt counter electrode.

• 한국광학회지
• /
• 제10권6호
• /
• pp.524-526
• /
• 1999

본 논문에서는 외부 공진기 반도체 링 레이저 내부에 에탈론을 삽입함으로써 외부 공진기 링 레이저의 종모드 간격이 현저히 변화하는 사실을 관측하고 이에 대한 이론적 분석을 수행하였다. 외부공진기 링 레이저의 종 모드 간격은 에탈론의 단면 반사율에 의존하여 변화하였으며, 공진모드의 분석을 통해 이에 대한 정량적인 해석을 보였다. 또한 이러한 효과가 에탈론이나 FP 필터의 단면 반사율의 정밀한 측정에 응용될 수 있다는 것을 실험을 통해 증명하였다. 제안된 방법은 특히 높은 반사율에 대해서도 정밀한 측정결과를 얻을 수 있으며 측정이 쉽고 매우 빠르게 이루어진다.

• 해양환경안전학회지
• /
• 제3권2호
• /
• pp.85-92
• /
• 1997

To determine an operational condition of an adhesion-type oil skimmer, it is important to estimate the withdrawal rate for a given driving velocity of the skimmer and material properties of the oil. As a theoretical model for this problem the formation of an oil film on a vertically driven flat plate is investigated. The previous steady-state analysis made in the field of coating industry are reviewed. These studies have been made under the assumptions of small Reynolds and capillary number, which is adequate for coating process but not for oil skimming. An alternative analysis based on the linear stability theory is made. Comparisons with the experimental results reveal that the stability analysis gives a correct estimation of the withdrawal rate for high capillary number at which the previous theory losses its validity.

• 한국분말재료학회지
• /
• 제8권4호
• /
• pp.253-257
• /
• 2001

The effects of mechanical alloying conditions on the formation of Mn-sulfide powders were analyzed. Impeller rotating speed, lubricant coating and added amounts of process control agent(stearic acid) were selected as a process control factor. MnS compounds are synthesized in 3 hours by mechanical alloying at the alternative milling condition. Discontinuous rotating speed of 1200rpm for 4 minutes and 1000rpm for 1 minute shows more effects on the compound formation of MnS. After coating of lubricant on the wall, elementary Mn and sulfur were partially remained by mechanical alloying. The friction effects of the wall and grinding media on the powders are significantly important to form the compound of MnS.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2003년도 추계학술발표회초록집
• /
• pp.11-11
• /
• 2003

Electroplated hexavalent chromium coatings have been used in many technical applications since it was invented by G.J. Sargent in 1920. Because of the environmental problems and health risks associated with the use of hexavalent chromium, there has been an extensive search for alternative coatings with properties such as corrosion resistance and wear resistance, at a reasonable cost. However there is no single substitute that meets all the desirable performance characteristics of chromium. Advanced techniques, such as alloy plating, electroless plating, trivalent chromium plating, plasma and thermal spray coating, PVD and ion implantation, have been applied for replacing hexavalent chromium plating.

• 한국산학기술학회논문지
• /
• 제20권12호
• /
• pp.804-815
• /
• 2019

화석연료의 고갈 및 지구 온난화 등 환경문제에 대응하기 위해 세계는 화석연료를 대신할 에너지에 대한 연구를 진행하였고, 그중 바이오매스가 대체에너지로써 주목받고 있다. 바이오매스는 재생 가능하고 탄소 중립(carbon neutral)적인 특성이 있으나 수분함량이 많고 낮은 에너지밀도를 가지므로 에너지 생산 시스템에 이용하기 위해서는 열화학적 변환 공정이 필요하다. 그중 하나인 가스화는 바이오매스로부터 수소, 일산화탄소, 메탄 등으로 구성된 합성가스(syngas)를 생성시켜 연료로써 이용할 수 있도록 해준다. 그러나 가스화 과정 중에 발생되는 타르와 입자상 물질은 배관, 연소 엔진, 발전 터빈 등에서 막힘 현상을 일으켜 공정 효율을 감소시키는 문제를 야기하므로 제거가 필요하다. 본 연구에서는 가스화 공정에서 발생되는 타르를 비롯한 입자물질에 대해 제거 효율이 뛰어난 필터를 사용하였으며, 타르로부터 필터 눈 막힘 현상을 방지하기 위해 pre-coating 기술을 적용하였다. pre-coating에 사용된 물질로써는 소석회와 활성탄(wood char)을 사용하였으며, 타르 및 입자에 대한 제거효율이 소석회 코팅의 경우 86 %, 활성탄(wood char)의 경우 80 %로 나타났다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.59-59
• /
• 2010

Graphene has attracted much interest because of its fascinating electronic structure with excellent electron mobility. However, there are some difficulties in making graphene of large and uniform area for real applications. One alternative is graphite oxide. Since graphite oxide is water soluble, it can be sprayed or spin-coating onto any substrates for applications such as Transparent Conducting Film (TCF) and Field Effect Transistor (FET). In this talk, chemical and physical properties of graphite oxide will be discussed. In addition, possible applications made of graphite oxide (GO) will be introduced.