• 한국재료학회지
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• 제3권3호
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• pp.215-222
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• 1993

에폭시 수지를 개질하기 위하여 반응성 첨가제 Malononitrild(MN)을 Diglycidy1 ether fo vispenol A (CGEBA)/Methylene dianiline(MDA)계를 첨가하여 이 계의 경화 반응속도론과 경화반응메카니즘을 시차주사 열분석(DSC)과 적외선 흡수 분광법을 통해 관찰하였다. 경화반응속도론으로부터 MN으로 개질된 DGEBA/MDA는 완전히 경화를 이루기 위하여 $80^{\circ}C$로 부터 $170^{\circ}C$까지 $30^{\circ}C$간격으로 경화시킨 시료로 반응메카니즘을 고찰한 결과 PA(primary amine)-E(epoxide)그리고 E(epoxide)-OH(hydroxy1 group)반응 이외에 PA(primary amine)-CN(nitrile)과 CN(nitrile)-OH(hydroxy1 group)반응이 일어남을 알았다.

• Elastomers and Composites
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• 제41권4호
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• pp.245-251
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• 2006

고무상으로 니트릴고무(NBR)을 플라스틱상으로 isotactic 폴리프로필렌(iPP)을 고무:플라스틱 비율이 70:30(wt:wt)되도록 내부혼합기에서 용융 혼합하고, 과산화물 가교제(DCP) 및 메타크릴산 아연염(ZDMA)을 첨가하여 동적 가교시킨 블렌드를 제조하였다. DCP만을 사용하여 동적가교시킨 블렌드에 비해 DCP와 ZDMA를 함께 첨가하여 제조한 동적가교시킨 블렌드가 우수한 인장물성, 인열강도 및 고무탄성을 나타내었다. 이는 메타크릴간 아연염의 첨가에 의해 동적가교과정 중 고무상의 가교밀도가 증가되고, 가교된 고무상이 플라스틱 연속상에 더 미세하게 분산되기 때문인 것으로 생각되었다. 또한, 제조된 블렌드는 반복 가공 시 물성의 큰 저하가 나타나지 않아 재활용성이 가능한 열가소성탄성체임을 알 수 있었다.

• 한국임상수의학회지
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• 제39권6호
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• pp.319-325
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• 2022

Two-port laparoscopic ovariectomy (Lap-OVE) has been performed in small dogs, using 3-mm and 5-mm portal sites, and is associated with reduced surgical stress and postoperative pain. However, extension of the incision is often needed to extract the ovaries. In this study, we aimed to minimize invasiveness by using smaller-sized cannulas as well as a novel technique for ovary extraction. Lap-OVE was performed on six, healthy female dogs (range, 3 to 7.2 kg) using two 3-mm midline portals. The middle finger of a size M nitrile glove was cut at its base and sterilized preoperatively. The ovary was suspended at the body wall using a 1-0 blue nylon needle, and the ovarian pedicle and ligaments were transected using a 3-mm bipolar forceps. To facilitate the glove passing through the 3.9-mm port, it was turned inside out to expose the smooth inner surface, before being inserted into the abdominal cavity with an applicator. Both ovaries were placed inside, and the mouth of the glove was exteriorized through the port with a laparoscopic grasping forceps. The ovaries were morcellated inside the glove, using Adison-Brown tissue forceps and iris scissors, which enabled safe extraction without incision enlargement. Median incision lengths were 4.3 mm (3.5-mm cranial cannula) and 4.8 mm (3.9-mm caudal cannula). An advantage of this procedure was that there was no need for skin sutures. In conclusion, using our novel technique, sutureless Lap-OVE was possible in small dogs using two 3-mm portal sites without additional incision.

• Tribology and Lubricants
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• 제14권2호
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• pp.21-25
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• 1998

This paper presents the experimental results of the friction characteristics of double liptype oil seals which show an improvement in sealing performance over single lip-type oil seals. The major differences between two oil seals are the number of contact lip, and seal materials; Nitrile Butadine Rubber(NBR) and urethane rubber. The measured results show that the friction torques of double lip seals show 12-17% increases compared with those of single lip-type seals. But the sealing performance and service life of double lip oil seals have been increased and stabilized due to an optimized design of the seal lip and material properties.

• Elastomers and Composites
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• 제52권4호
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• pp.280-286
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• 2017

The mechanical and dynamic properties according to the content of filler, plasticizer, and crosslinking agent of rubber composites for Lipseal were measured in this study. The mechanical properties of the composite including the silane coupling agent and silica were found to be superior to those of the composite containing carbon black. It was found that the rebound resilience characteristics were influenced by the crosslink density of sulfur rather than the filler or plasticizer. In the case of recovery, it was confirmed that the elastic restoring force improved in the compression deformation condition and recovery increased as the crosslinking density increased. The rubber composite for Lipseal of this study is expected to improve the manufacturing technology of the rubber composite which can implement the optimum function for recognizing the performance such as oil resistance, durability and compression set.

• Bulletin of the Korean Chemical Society
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• 제25권2호
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• pp.207-212
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• 2004

In this study, we attempted to prepare compounds with heterocyclic replacements for metabolically unstable esters of benzopyranyl indole-2-carboxylic esters, which showed good in vitro and in vivo cardioprotective efficacies possibly through the opening of mitochondrial ATP-sensitive potassium channel ($K_{ATP}$). Initially, we tried to construct indolin-2-yl-heterocycles using unprotected indoline-2-carboxylic acid, but the cyclization was proceeded with oxidation of the indoline ring to the indole, which didn't react with benzopyranyl epoxide. Thus we introduced N-Boc group to deplete the electron density of the indoline ring. We successfully prepared various indolin-2-yl-heterocycles by the cyclization of the building blocks including carboxamide, ${\beta}$-hydroxy amide, hydrazide, nitrile starting from N-Boc-indoline-2-carboxylic acid.

• 한국식품저장유통학회지
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• 제4권3호
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• pp.295-300
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• 1997

The water extract of mustard seed was fractionated by solvents with an increase of polarity, and antimicrobial activities of each extracts were examined, and volatile compounds of each extract were identified by GC-MS. When the water extract was fractionated with solvents, the antimicrobial activities were high in the order of chloroform, ethylacetate, hexane, butanol and aqueous layer. In chloroform fraction, 16 volatile compounds, including 2 isothiocyanates such as 3-isothiocyanato- 1-propene and 4-isothiocyanato- 1-butane, 1 nitrile and 4 acids were identified, their contents were higher than other fractions. Twelve, 10, 4 and 7 volatile compounds were identified in ethylaceate, hexane, butanol and water fractions, respectively. The volatile compounds were considerably less in the fractions of butanol and water than others.

• Tribology and Lubricants
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• 제10권2호
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• pp.39-42
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• 1994

This paper deals with the distributions of the contact stress in oil seals. The distributions of the contact stress due to the temperature effects are analyzed for various values of the interference for a nitrile rubber seal. The calculated FEM results show that the relative maximum stresses occur at the contacting area against the shaft, the flex zone, and the contacting area of the garter spring grooves. Using the coupled temperature-stress FEM a nalysis, the contact force of a radial lip seal with and without the garter spring are studied as a function of shaft diameter. The calculated results of mechanical analysis show good correspondence with those of the coupled thermal-mechanical analysis method except small values of the interference. And the calculated results indicated that the thermal stresses only have a very minor influence on the deformed shape of the lip seal as the interference increases. But the coupled temperature-stress analysis will be very useful tool to predict the contact behaviors of rubber lip seals for small values of the interference.

• 한국염색가공학회지
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• 제19권1호
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• pp.45-52
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• 2007

Polyacrylonitrile(PAN) fiber was treated with low-temperature plasmas of argon and oxygen for surface modification, and its surface chemical structure and morphology were examined by a field emission scanning electron microscope(FESEM) and a Fourier-transform infrared microspectroscopy(IMS). The argon-plasma treatment caused the only mechanical effect by sputtering of ion bombardment, whereas the oxygen plasma brought about a chemical effect on the PAN fiber surface. The experimental evidences strongly suggested that cyclization of nitrile group and crosslinking were likely to occur in the oxygen-plasma treatment. On the other hand, with the argon-plasma treatment, numerous my pits resulted in ranging from several tens to hundreds nanometers in radius. The plasma sensitivity of functional groups such as C-H, $C{\equiv}N$, and O-C=O groups in the PAN fiber was dependent on their chemical nature of bonding in the oxygen-plasma, in which the ester group was the most sensitive to the plasma. Vacuum-ultraviolet(VUV) radiation emitted during plasma treatment played no substantial role to alter the surface morphology.

• 한국정밀공학회지
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• 제23권12호
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• pp.80-87
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• 2006

Seals are usually made from elastomer, a kind of rubber, and it has the non-linearity and hyper-elasticity. U-type seals are used to prevent the leakage of internal fluid sealed in hydraulic actuator because they have more excellent performance than O-rings or rectangular seals. As a core part of hydraulic actuator, U-type seal gives much effect on performance and reliability of actuator. This study considers an NBR U-type seal under high pressure of a hydraulic actuator, and provides its deformation, stress-strain characteristic and contact force using the non-linear finite element analysis. Analysis results are compared with the experimental ones performed by the self-developed testing equipment. Verification result shows that this study presents a good application process for the effective design of U-type seals under high operation pressure.