• 전기학회논문지
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• 제57권12호
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• pp.2249-2254
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• 2008

A non-thermal micron size plasma needle is applicable for medical treatment because it includes radicals, charged particles, ultraviolet emission, and strong electric fields. The electric fields around the plasma needle device driven by a radio frequency wave are investigated in order to calculate the power delivered to the cell. A commercial multi-physics code, CFD-ACE, was utilized for the calculation of electric fields for the optimization of the needle structure. The electric field and energy absorption profiles are presented with the variation of the device structure and the distance between the needle and tissues. The living tissues effectively absorb the radio frequency power from the plasma needle device with the covered pyrex structure.

• Design & Manufacturing
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• 제13권3호
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• pp.48-52
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• 2019

As the consumer market in the mold, automation and aerospace industries grows, the demand for chemical machining using on electrochemical polishing increases. To enhance the surface roughness and gloss of the micro-needle, we have studied for an electrochemical polishing. Electrochemical polishing requires the chemical reaction of solution and material according to the electrolyte and electrode. In this study, sulfuric acid(30%), phosphoric acid(50%), and DI-water(20%)were used as the electrolytic solution, and the electrolytic solution temperature used $58^{\circ}C$. Electrochemical polishing was carried out in experimental conditions, and the micro-needle experiment was carried out from the basic experiment to obtain the experimental conditions. Experimental results show that as the voltage and current increase, the surface roughness improved and the gloss is improved. So, the best result for this experiment was obtained in condition 6, which improved micro-needle.

• 전기학회논문지
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• 제56권11호
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• pp.1972-1977
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• 2007

Micro plasma has been recently studied to investigate the effects on various cells. We study a micro-plasma produced by a plasma needle that is operated with RF power and its effects on G361 melanoma cells. The micro plasma size ranges from sub-mm to several mm at a few watts of RF power. For the bio-medical treatment, low-temperature plasma is obtained and gas temperature is controlled within several tens of degrees $(^{\circ}C)$ in order not to disturb cell activities. Elementary spectroscopic studies to obtain plasma characteristics are presented for Ar and He plasma with different frequencies of RF power. Also the preliminary results of the micro plasma effects on G361 melanoma cells are presented. It was observed that the irradiation of micro plasma induces cell death through the deprivation of tyrosine phosphorylation in the G361 cells.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2011년도 춘계학술대회 논문집
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• pp.599-600
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• 2011

• 폴리머
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• 제37권3호
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• pp.393-398
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• 2013

본 실험에선 미녹시딜을 함유한 수용성 고분자 젤로부터 solvent casting 방법으로 250과 $750{\mu}m$ 두 가지 길이의 미녹시딜이 함유된 용융형 고분자 마이크로 니들(micro-needle)을 제작하였다. 제작된 미녹시딜을 함유한 용융형 고분자 마이크로 니들은 기계적 강도가 입증된 고분자 니들과 동일한 형태 및 기계적 강도를 나타냈으며, 성공적으로 피부를 투과함을 확인하였다. 제조된 고분자 마이크로 니들의 경우 피부 적용 후 최소 30분 이상은 부착되어야 전체 니들의 50% (v/v) 이상이 피부 내로 용융되었으며, 니들 적용부위에서 서서히 약물의 방출 및 확산을 확인할 수 있었다. 또한 C57BL/6 동물 모델을 통해 미녹시딜이 함유된 250, $750{\mu}m$ 길이의 고분자 마이크로 니들이 무처리군 혹은 미녹시딜 처리군에 비해 발모에 긍정적인 영향을 나타냄을 확인할 수 있었다.

• International Journal of Korean Welding Society
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• 제2권2호
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• pp.19-25
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• 2002

In recent years, techniques for micro-assembly with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Adhesion phenomenon is more significant for smaller objects, because adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. It is also known that adhesional force between micro-objects exposed to Electron Beam irradiation of SEM increases with the elapsed time. Therefore, mechanical manipulation techniques using a needle-shaped tool by adhesional force are often adopted in basic researches where micro-objects are studied. These techniques, however, have not yet achieved the desired repeatability because many of these could not have been supported theoretically. Some techniques even need the process of trial-and-error. Thus, in this paper, mechanical and adhesional micro-manipulation are analyzed theoretically by introducing new physical factors, such as adhesional force and rolling-resistance, into the kinematic system consisting of a sphere, a needle-shaped tool, and a substrate. Through this analysis, they are revealed that how the micro-sphere behavior depends on the given conditions, and that it is possible to cause the fracture of the desired contact Interfaces selectively by controlling the force direction in which the tool-tip loads to the sphere. Based on the acquired knowledge, a mode diagram, which indicates the micro-sphere behavior for the given conditions, is designed. By referring to this mode diagram, the practical technique of the pick and place manipulation of a micro-sphere under an SEM by the selective interface fracture is proposed.

• 한국전산구조공학회논문집
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• 제34권1호
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• pp.51-58
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• 2021

본 논문에서는 Needle-punched C/SiC 복합재료 해석을 위한 효율적인 멀티스케일 해석기법을 소개한다. 기존 Needle-punching으로 인해 복잡한 미소구조를 갖는 NP 복합재료는 기존의 제안된 복합재료 멀티스케일 기법으로 물성을 계산하는 것은 한계가 있어 왔다. 이를 극복하기 위해 micro-CT 이미지 촬영을 통해 NP 복합재료의 미소구조를 면밀히 파악할 수 있었고, 이미지 프로세싱을 바탕으로 실제구조와 직접적으로 대응할 수 있는 3D high fidelity 모델을 구축하였다. 또한 유한요소해석에 맞춰 요소크기를 조절할 수 있는 sub-region processing 소개를 바탕으로 효율적인 유한요소해석을 수행하였다. NP 복합재료의 미소구조 거동뿐만 아니라, macro-scale 구조해석의 적용을 위해 subcell 모델링을 제안하였다. Needle-punching에 의한 Z축 NP 섬유의 규칙적인 간격을 이용하여 모델링을 수행할 수 있었다. 제안한 두 종류의 모델은 균질화 기법을 이용하여 등가거동 및 등가물성을 파악하였으며, 추가적인 실험 결과와의 비교를 통해 검증을 수행하였다.

• E2M - 전기 전자와 첨단 소재
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• 제30권5호
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• pp.3-8
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• 2017

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.720-725
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• 2002

In recent years, techniques for micro-assembly with high repeatability under a scanning electron microscope (SEM) are required to construct highly functional micro-devices. Adhesion phenomenon is more significant for smaller objects, becanse adhesional force is proportional to size of the objects while gravitational force is proportional to the third power of it. It is also known that adhesional force between micro-objects exposed to Electron Beam irradiation of SEM increases with the elapsed time. Therefore, mechanical manipulation techniques using a needle-shaped tool by adhesional force are often adopted in basic researches where micro-objects are studied. These techniques, however, have not yet achieved the desired repeatability because many of these could not have been supported theoretically. Some techniques even need the process of trial-and-error. Thus, in this paper, mechanical and adhesional micro-manipulation are analyzed theoretically by introducing new physical factors, such as adhesional force and rolling-resistance, into the kinematic system consisting of a sphere, a needle-shaped tool, and a substrate. Through this analysis, they are revealed that how the micro-sphere behavior depends on the given conditions, and that it is possible to cause the fracture of the desired contact interfaces selectively by controlling the force direction in which the tool-tip loads to the sphere. Based on the acquired knowledge, a mode diagram, which indicates the micro-sphere behavior for the given conditions, is designed. By refening to this mode diagram, the practical technique of the pick and place manipulation of a micro-sphere under an SEM by the selective interface fracture is proposed.

• 한국레이저가공학회지
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• 제15권3호
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• pp.1-6
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• 2012

The friction force of patterned needle in elastomer have been investigated to verify the application for bio and plastic industry. The micro pattern on the needle surface were prepared by 266 nm, 20 ns laser and 800 nm, 220 fs laser, which were able to generate the different surface roughness. The friction force was measured by the load cell of 10 N capacity. As the results, the friction force of no patterned needle is almost constant during the needle penetrates the silicone rubber sample. However, the needle having asperities shows the variation of the friction force. The higher the surface roughness is, the smaller the friction force is until the surface roughness is very high. In our experiment conditions, the reduction of the friction force by 20 % compared to no pattern needle was achieved with straight and $50{\mu}m$ discrete line generated by 266 nm, 20 ns laser.