• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.380.2-380.2
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• 2016

The emergence of new infectious diseases, the resurgence of several infections that appeared to have been controlled and the increase in bacterial resistance have created the necessity for studies directed towards the development of new antimicrobials. In the present study, we have synthesized a novel antioxidant ZnO nanoparticle that is newly designed and prepared by simple surface modification process. Antioxidative functionality is provided by the immobilization of antioxidant 3-(3,4-dihydroxyphenyl)-2-propenoic acid (caffeic acid, CA) onto the surface of ZnO nanoparticles. Microstructure and physical properties of the ZnO@CA nanoparticles were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR) and steady state spectroscopic methods. Antimicrobial Activities of ZnO@CA nanoparticles were measured against various bacterial strains using antibacterial testing methods.

• 한국공작기계학회논문집
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• 제16권5호
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• pp.55-62
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• 2007

With the developments in knitting, manufacturing, and polymers, coated gloves have been evolved in a way to maximize occupational safety and functionality. In this paper, we have considered the PU-coating process for the glove knitted by Dyneema to reduce the occurrence of the defects due to air bubble. This paper classifies the types of defect due to air bubble and traces their forming mechanisms. The air between coating layer of glove and mold's surface forms the defects if it is not evacuated fully in the process of submerging into water. The defects can be suppressed or avoided by forming air-evacuating path on the surface of the molds.

• 한국표면공학회지
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• 제47권6호
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• pp.362-367
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• 2014

We report the design, fabrication of a $Si_3N_4$ probe and calculation of its mechanical properties for DPN(dip pen nanolithography), which consists of dual tips. Concept of dual tip probe is to employ individual tips on probe as either an AFM tip for imaging or a writing tip for nano patterning. For this, the dual tip probe is fabricated using low residual stress $Si_3N_4$ material with LPCVD deposition and MEMS fabrication process. On the basis of FEM analysis we show that the functionality of dual tip probe for imaging is dependent on the dimensions of dual tip probe, and high ratio of widths of beam areas is preferred to minimize curvature variation on probe.

• 대한의용생체공학회:의공학회지
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• 제43권2호
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• pp.94-101
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• 2022

Recent advancement of micro/nano technology enables the development of diverse micro/nano particle-based delivery systems. Due to the multi-functionality and engineerability, particle-based delivery system are expected to be a promising method for delivery to the target cell. Since the particle-based delivery system should be delivered to the various kinds of target cell, including the cardiovascular system, cancer cell etc., it is frequently decorated with multiple kinds of targeting molecule(s) to induce specific interaction to the target cell. The surface decorated molecules interact with the cell surface expressed molecule(s) to specifically form a firm adhesion. Thus, in this study, the probability of adhesion is estimated to predict the possibility to form a firm adhesion for the multi-ligand decorated particle-based delivery system.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2009년도 추계학술발표대회
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• pp.12.1-12.1
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• 2009

Nano-hydroxyapatite (N-HAp)has shown the pivotal role in producing bone-regenerative materials since it has similarity to natural bone minerals in terms of size, morphology, and the composition. Currently, the combination of biopolymers and N-HAp is recognizedas an attractive approach in generating hybrid scaffolds for bone tissueengineering. Surface engineering is an important issue since it determines whether cells can effectively adhere and proliferate on porous scaffolds. We aim to develop a synthetic approach to porous 3D scaffolds by immobilizing N-HAp on pore surfaces. The discrete nano-level anchoring of N-HAp on the scaffold pore surface is achieved using surface-repellent stable colloidal N-HAp with surface phosphate functionality. This rational surface engineering enables surface-anchored N-HAp to express its overall intrinsic bioactivity,since N-HAp is not phase-mixed with the polymers. The porous polymer scaffolds with surface-immobilized N-HAp provide more favorable environments thanconventional bulk phase-mixed polymer/N-HAp scaffolds in terms of cellular interaction and growth. In vitro biological evaluation using alkalinephosphatase activity assay supports that immobilized N-HAp on pore surfaces of polymer scaffolds contributed to the more enhanced in vitro osteogenicpotential. Besides, the scaffolds with surface-exposed N-HAp provide favorable environments for enhanced in vivo bone tissue growth, estimated by characteristic biomarkers of bone formation such as collagen. The results suggest that newly developed hybrid scaffolds with surface-immobilized N-HApmay serve as a useful 3D substrate with pore surfaces featuring excellent bonetissue-regenerative properties. Acknowledgement. This research was supported by a grant (code #: 2009K000430) from 'Center for Nanostructured Materials Technology' under '21st Century Frontier R&D Programs' of the Ministry of Education, Science and Technology, Korea.

• Elastomers and Composites
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• 제35권2호
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• pp.98-105
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• 2000

화학적 표면처리에 따른 카본블랙의 표면 관능기와 표면 자유에너지를 FT-IR과 접촉각 측정법을 이용하여 각각 관찰하였다. 산성과 염기성 용액으로 표면 처리한 카본블랙을 분석한 결과, 표면 관능기가 표면 자유에너지의 극성요소에 크게 영향을 미치는 것을 확인하였다. 반면에 무극성 용액으로 표면처리한 NCB와 염기성 용액으로 처리한 BCB의 경우 표면 자유에너지의 London 비극성 요소의 증가를 보이며 이에 따라 카본블랙/고무 복합재료의 경도, 파단신율, 그리고 인장강도와 같은 기계적 물성이 증가하는 것을 볼 수 있었다. 특히, 접촉각 측정을 통해 얻은 표면 자유에너지의 London 비극성 요소가 복합재료의 인장강도와 상관관계가 있음을 확인할 수 있었다. 이는 카본블랙의 London 비극성 요소가 카본블랙/고무 복합재료의 기본적인 기계적 물성에 크게 기여한다고 사료된다.

• 마이크로전자및패키징학회지
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• 제23권4호
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• pp.107-112
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• 2016

본 논문에서는 나노임프린트 리소그래피 기술을 이용하여 다양한 발수 표면을 제작하였으며, 발수기능의 안정성을 향상시키기 위해 액적의 충돌 거동에 대하여 평탄한 단위면적에 대한 구조물의 면적비인 표면 변수의 영향에 대한 연구를 수행하였다. 액적의 충돌 거동을 연구하기 위해 액적 충돌 시험을 통하여 충돌한 액적이 되튐에서 분산으로 천이 되는 임계높이를 측정하였다. 높은 표면 변수에서는 낮은 임계높이가 관찰되었으나, 낮은 표면변수에서는 임계높이가 증가하는 경향을 관찰하였다. 그러나, 표면변수가 더욱 감소할 경우 임계높이가 다시 감소하는 경향을 보였다. 관찰된 결과는 높은 임계높이를 위해서는 최적의 표면 형상 설계가 요구됨을 제시하고 있다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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• pp.202-202
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• 1999

The Polyethylene (PE), Polystyrene (PS) and Polytetrafluoroethylene (PTFE) surface modification was investigated by hydrogen io assisted reaction (H-IAR) in oxygen environment. The IAR is a kind of surface modification techniques using ion beam irradiation in reactive gas environment. The energy of hydrogen ion beam was fixed at 1keV, io dose was varied from 5$\times$1014 to 1$\times$1017 ions/$\textrm{cm}^2$, and amount of oxygen blowing gas was fixed 4ml/min. Wettability was measured by water contact angles measurement, and the surface functionality was analyzed by x-ray photoelectron spectroscopy. The contact angle of water on PE modified by argon ion beam only decrease from 95$^{\circ}$ to 52$^{\circ}$, and surface energy was not changed significantly. But, the contact angle using hydrogen ion beam with flowing 4ml/min oxygen stiffly decreased to 8$^{\circ}$ and surface energy to 65 ergs/cm. In case of PS, the contact angle and surface energy changes were similar results of PE, but the contact angle of PTEE samples decreased with ion dose up to 1$\times$1015 ions/$\textrm{cm}^2$, increased at higher dose, and finally increased to the extent that no wetting was appeared at 1$\times$1017 ions/$\textrm{cm}^2$. These results must be due to the hydrogen ion beam that cleans the surface removing the impurities on polymer surfaces, then hydrogen ion beam was activated with C-H bonding to make some functional groups in order to react with the oxygen gases. Finally, unstable polymer surface can be changed from hydrophobic to hydrophilic formation such as C-O and C=O that were confirmed by the XPS analysis, conclusionally, the ion assisted reaction is very effective tools to attach reactive ion species to form functional groups on C-C bond chains of PE, PS and PTFE.

• Elastomers and Composites
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• 제39권1호
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• pp.3-11
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• 2004

플라즈마 표면처리는 표면 관능기 표면 활성도 등을 증가시켜 촉매적 선택성, 염색성 및 다양한 소재의 접착력을 증가시켜주는데 큰 역할을 담당한다. 본 연구에서는 dielectric barrier discharge (DBD)를 이용한 상압 플라즈마 토치로 ethylene-vinyl acetate (EVA)의 표면을 처리하였다. 이때 사용된 가스는 아르곤, 공기, 및 산소를 이용하였으며, 표면처리에 따른 EVA의 표면 특성을 제타전위와 표면자유에너지를 이용하여 관찰하였다. 그 결과, 상압 플라즈마 표면처리에 따른 EVA의 표면 관능기는 접착 에너지 ($G_{IC}$)와 비례관계를 가지며 증가하는 것을 확인하였다. 특히, 상압 플라즈마 표면처리 공정은 EVA와 polyurethane (PU) 계면의 접착력을 크게 증가시켜 주는 것을 확인하였다.

• Food Science and Biotechnology
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• 제17권2호
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• pp.379-383
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• 2008

Extraction characteristics of garlic and functional properties of corresponding extract were monitored by response surface methodology (RSM). Maximum extraction yield of 26.41% was obtained at microwave power of 146.29 W, ethanol concentration of 63.31 %, and extraction time of 5.88 min. At microwave power, ethanol concentration, and extraction time of 114.84 W, 58.83%, and 1.42 min, respectively, maximum electron-donating ability (EDA) was 72.86%. Maximum nitrite-scavenging ability was 94.62% at microwave power, ethanol concentration, and extraction time of 81.83 W, 2.65%, and 3.83 min, respectively. Superoxide dismutase (SOD) showed maximum pseudo-activity of 49.12% at microwave power of 34.23 W, ethanol concentration of 33.11 %, and extraction time of 4.40 min. Based on superimposition of 4-dimensional RSM with respect to extraction yield, electron-donating ability, nitrite-scavenging ability, and pseudo-activity of SOD, optimum ranges of extraction conditions were microwave power of 0-100 W, ethanol concentration of 40-70%, and extraction time of 2-8 min.