• 한국세라믹학회지
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• 제42권2호
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• pp.117-122
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• 2005

나노 코팅 기술로써 빠른 증착 속도와 미세구조 제어가 용이하여 항공기 엔진 부품 열차폐 코팅으로 널리 이용되는 Electron Beam Physical Vapor Deposition (EB-PVD)세라믹 코팅 기술을 연료전지 전해질 제조에 적용하였다. EB-PVD 법을 이용하여 NiO-YSZ 기판에 YSZ 전해질을 약 10$\mu$m의 두께로 짧은 시간에 코팅하였으며 증착온도에 따라 나노 구조의 표면을 가진 YSZ 막을 얻을 수 있었다. 연료전지 전해질로서의 특성을 평가하기 위하여, 같은 조건의 코팅으로 $Al_{2}O_3$기판에 전해질을 동일한 조건으로 코팅하여 전해질의 전기적 특성을 평가하였다. 또한 양극물질로서 $LaSrCoO_3$ 분말을 일반적인 스크린 프린팅 기법으로 코팅하여 EB-PVD의 코팅을 이용한 고체산화물 연료전지 제조 가능성에 대하여 논의하였다

• 대한기계학회논문집A
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• 제34권9호
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• pp.1227-1233
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• 2010

가스터빈엔진 내의 블레이드에서는 표면에 외부의 찬 공기를 흘려주는 작은 냉각 홀들을 가공하고 열 차단 코팅시스템을 코팅하는 방법으로 기지금속을 고온에서 보호한다. 열 차단 코팅은 열피로 과정에서 산화막의 성장 및 접합층과 산화막의 열팽창계수의 불일치로 산화막내부에 잔류응력이 발생하며 궁극적으로 코팅층의 분리를 유발한다. 본 연구에서는 내열합금 시편 표면에 작은 홀을 가공하여 여러 가지 고온 유지 조건에서 열 및 기계적 피로 시험을 수행하여 홀 주위의 산화막의 변형을 관찰하였다. 실험결과 기계적 피로가 홀 주위의 산화막의 변형에 중요한 영향을 미치며, 동일한 산화막 두께에서 고온 유지 시간이 짧을수록 변형이 쉽게 발생 하였다. 또한 본 연구에서는 홀 주위 산화막의 응력해석을 위한 이론적인 연구도 시도되었다.

• 대한기계학회논문집A
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• 제38권5호
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• pp.559-566
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• 2014

제철공장의 소결대차 스틸바의 내열성, 내마모성, 내부식성 등의 성질을 향상시키기 위하여 용사코팅을 적용한 연구가 진행되었다. 약 $700^{\circ}C$의 고온환경에서 내열, 내마모, 부식 등에 노출되어 있는 스틸의 표면에 $Al_2O_3$, $Cr_2O_3$, WC 코팅을 적용하여 국부적으로 고온내마모성, 내식성, 내열성, 내열충격성 등을 향상시킴으로써 기존 제강공정에서 사용되는 스틸바의 수명을 향상시켰다. 스틸바에 적용한 금속용사 코팅층에 대하여 고온내마모시험, 열충격시험, 내부식시험을 수행하였다. 코팅층의 물리적, 화학적, 기계적 특성이 코팅이 안된 재료에 비해 매우 우수하였다.

• 한국정밀공학회지
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• 제24권4호
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• pp.138-146
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• 2007

Some biodegradable polymers and other materials such as hydrogels have shown the promising potential for surgical applications. Post surgical adhesion caused by the natural consequence of surgical wound healing results in repeated surgery and harmful effects. Recently, scientists have developed absorbable anti-adhesion barriers that can protect a tissue from adhesion in case they are in use; however, they are dissolved when no longer needed. Although these approaches have been attempted to fulfill the criteria for adhesion prevention, none can perfectly prevent adhesions in all situations. Overall, we developed a new method to fabricate an anti-adhesion membrane using biodegradable polymer and hydrogel. It employed a highly accurate three-dimensional positioning system with pressure-controlled syringe to deposit biopolymer solution. The pressure-activated microsyringe was equipped with fine-bore nozzles of various inner-diameters. This process allowed that inner and outer shapes could be controlled arbitrarily when it was applied to a surgical region with arbitrary shapes. In order to fulfill the properties of the ideal barriers f3r preventing postoperative adhesion, we adopted the pre-mentioned method combined with surface modification with the hydrogel coating by which anti-adhesion property was improved.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.158-158
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• 2012

A new kind of organic-inorganic hybrid polymer, poly(tetraphenyl)silole siloxane (PSS), was invented and synthesized for realization of its unique charge trap properties. The organic portions consisting of (tetraphenyl)silole rings are responsible for electron trapping owing to their low-lying LUMO, while the Si-O-Si inorganic linkages of high HOMO-LUMO gap provide the intrachain energy barrier for controlling electron transport. Such an alternation of the organic and inorganic moieties in a polymer may give an interesting quantum well electronic structure in a molecule. The PSS thin film was fabricated by spin-coating of the PSS solution in THF organic solvent onto Si-wafer substrates and curing. The electron trapping of the PSS thin films was confirmed by the capacitance-voltage (C-V) measurements performed within the metal-insulator-semiconductor (MIS) device structure. And the quantum well electronic structure of the PSS thin film, which was thought to be the origin of the electron trapping, was investigated by a combination of theoretical and experimental methods: density functional theory (DFT) calculations in Gaussian03 package and spectroscopic techniques such as near edge X-ray absorption fine structure spectroscopy (NEXAFS) and photoemission spectroscopy (PES). The electron trapping properties of the PSS thin film of quantum well structure are closely related to intra- and inter-polymer chain electron transports. Among them, the intra-chain electron transport was theoretically studied using the Atomistix Toolkit (ATK) software based on the non-equilibrium Green's function (NEGF) method in conjunction with the DFT.

• 한국식품과학회지
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• 제44권2호
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• pp.162-167
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• 2012

톳으로부터 HPH를 이용해 식품에 적용 가능성이 있는 가식성 필름을 제작할 수 있었다. HPH 처리 압력의 증가는 필름의 강도와 깨짐성을 증가시켰고, 단면이 조밀하고 균일한 필름을 형성시켰다. HPH의 처리 횟수의 증가 또한 필름의 단면을 조밀하게 하였다. 개발된 톳 필름은 보고된 많은 다른 생고분자 필름들에 비해 상대적으로 강도, 깨짐성, 그리고 수분 저항력이 낮아 코팅 또는 롤을 비롯한 필름 형태로 건조 식품 또는 중간 수분 식품에 적용될 수 있는 가능성을 보여주었다.

• 폴리머
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• 제31권3호
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• pp.177-183
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• 2007

본 연구에서는 라벤더 오일을 심물질로 이용하여 나노크기의 폴리(비닐 아세테이트)(poly(vinyl acetate), PVAc) 방향 입자를 유화-확산법으로 제조하였다. 방향 물질의 방출 시기와 속도 조절로 방향 캡슐의 지속성과 내구성을 얻기 위하여 제조 조건에 따른 나노 방향 입자의 특성과 방출 거동을 주사 전자 현미경, 전기 영동 광산란 분광 분석기, 자외선-가시광선 분광 분석기 및 고성능 액체 크로마토그래피를 이용하여 고찰하였다. 제조된 방향 입자는 실험 조건을 조절함에 따라 평균 입자 크기가 224 nm인 구상 나노 입자로 제조하는 것이 가능하였으며, 170시간 동안의 방출 거동을 비교.평가한 결과 PVA로 코팅한 방향 입자가 더 지속적이고 안정적인 초기 방출 거동을 보임을 확인할 수 있었다. 본 연구의 PVAc 나노 방향 입자는 직물 및 피혁제품 등에 대한 내구성 방향가공에 적용될 수 있을 것으로 기대된다.

• 산업기술연구
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• 제23권A호
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• pp.199-206
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• 2003

The charcoal-encapsulated methyl silica microcapsules were prepared by a O/W microemulsion sol-gel method, and the adsorption properties on aquatic humic acid were investigated. The capsules prepared were spherical, $100{\sim}1000{\mu}m$ in size. The size distribution was controllable by adjusting the size of charcoal powder, charcoal/methyl silica ratio, and agitating speed in O/W sol-gel process. Adsorption efficiency of charcoal for aquatic humic acid was decreased after encapsulation by methyl silica shell. The decreased adsorption efficiency can be dependent on the decrease of the BET surface area and pore volume after encapsulation. Diffusion properties of humic acid through the capsule shell also played an important role on adsorption efficiency. Therefore, the reasonable target pollutants for the capsules can be VOC or odor molecules which can overcome diffusion barrier through shell of capsules in air condition. Functionalization methods for the charcoal-encapsulated $CH_3(SiO)_n$ microcapsules by incorporation of $TiO_3$ as a phtocatalytic function and by incorporation of inorganic pigment as a color function were also investigated. $TiO_2$ coating properties were controllable by adjusting pH, temperature, and the concentration of $TiOSO_4$. In XRD measurement, the crystal form of the coated $TiO_2$ was anatase. For the colorization of the capsules, inorganic pigments were more efficient than organic dyes, and various color was introduced to the capsules using inorganic pigments.

• Journal of Information Display
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• 제2권2호
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• pp.52-60
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• 2001

The electrical and mechanical properties in indium-tin-oxide films deposited on polymer substrate were examined. The materials of substrates were polyethersulfone (PES) which have gas barrier layer and anti-glare coating for plastic-based devices. The experiments were performed by rf-magnetron sputtering using a special instrument and buffer layers. Therefore, we obtained a very flat polymer substrate deposited ITO film and investigated the effects of buffer layers, and the instrument. Moreover, the influences of an oxygen partial pressure and post-deposition annealing in ITO films deposited on polymer substrates were clarified. X-ray diffraction observation, measurement of electrical property, and optical microscope observation were performed for the investigation of micro-structure and electro-mechanical properties, and they indicated that as-deposited ITO thin films are amorphous and become quasi-crystalline after adjusting oxygen partial pressure and thermal annealing above $180^{\circ}C$. As a result, we obtained 20-25 ${\Omega}/sq$ of ITO films with good transmittance (above 80 %) of oxygen contents with under 0.2 % and vacuum annealing. Furthermore, using organic buffer layer, we obtained ITO films which have a rather high electrical resistance (40-45 ${\Omega}/sq$) but have improved optical (more than 85 %) and mechanical characteristics compared to the counterparts. Consequently, a prototype reflective color plastic film LCD was fabricated using the PES polymer substrates to confirm whether the ITO films could be realized in accordance with our experimental results.

• 한국유체기계학회 논문집
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• 제18권2호
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• pp.60-66
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• 2015

Conjugate heat transfer analysis was performed to investigate the flow and cooling performance of the high pressure turbine nozzle of gas turbine engine. The CHT code was verified by comparison between CFD results and experimental results of C3X vane. The combination of k-${\omega}$ based SST turbulence model and transition model was used to solve the flow and thermal field of the fluid zone and the material property of CMSX-4 was applied to the solid zone. The turbine nozzle has two internal cooling channels and each channel has a complex cooling configurations, such as the film cooling, jet impingement, pedestal and rib turbulator. The parabolic temperature profile was given to the inlet condition of the nozzle to simulate the combustor exit condition. The flow characteristics were analyzed by comparing with uncooled nozzle vane. The Mach number around the vane increased due to the increase of coolant mass flow flowed in the main flow passage. The maximum cooling effectiveness (91 %) at the vane surface is located in the middle of pressure side which is effected by the film cooling and the rib turbulrator. The region of the minimum cooling effectiveness (44.8 %) was positioned at the leading edge. And the results show that the TBC layer increases the average cooling effectiveness up to 18 %.