• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.274-279
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• 2002

In this paper, the development process of an unique and creative micro/nano-structure fabrication technique based on micro/nano-tribology are reviewed and discussed. The so-called Mechano-Chemical Process(MCP), which has been developed since 1995 by Tribology Research Laboratory at Yonsei University with the motivation to overcome the demerits of the conventional photolithographic techniques, is based on the fundamental understanding of the interaction between the tool tip and the workpiece surface. This process is a maskless process which offers tremendous flexibility in surface patterns that can be created on a workpiece surface without using any capital intensive equipment. It Is capable of fabricating the prototypes of micro/nano-components, micro- structured surface with various geometries, micro-molds for making polymer or metal parts, and micro-fluidic channels for lab-on-a- chip

• Journal of the Korean Society for Precision Engineering
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• v.27 no.6
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• pp.7-16
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• 2010

Physical fundamentals of ultrashort femtosecond lasers are addressed along with emerging applications for precision manufacturing and metrology. Femtosecond lasers emit short pulses whose temporal width is in the range of less than a picosecond to a few femtoseconds, thereby enabling extremely high peak-power machining with less thermal damages. Besides, the broad spectral bandwidth of femtosecond lasers constructed in the form of frequency comb permits absolute distance measurements leading to ultraprecision positioning control and dimensional metrology.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.13 no.2
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• pp.21-27
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• 2014

Recently, various biochip environments have been presented. In this study, a novel transparent film with porous membrane windows, which is an essential component in a co-cultured biochip environment, is fabricated using spin-coating, 3D printing, and electrospinning processes. In detail, a transparent polystyrene film was fabricated by means of the spin-coating process followed bywindow cutting, after which apolycaprolactone-chloroform solution was deposited along the window edge to introduce an adhesion layer between the PS film and the PCL nanofibers. Nanofibers were electrospun into the window region using a direct-write electrospinning method. Consequently, it was demonstrated that the fabricated window film could be used in a co-culture biochip environment.

• Polymer(Korea)
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• v.31 no.3
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• pp.215-220
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• 2007

The control of the surface energy by electrohydrodynamic force provides electrospraying with various potential advantages such as simple particle size control, mono-dispersity, high recovery, and mild processing conditions. The advantages are quite helpful to improve the stability of protein drug and control its release. Herein, the nano-encapsulation of protein drugs using electrospraying was investigated. Albumin as a model protein was processed using uniaxial and co-axial electrospraying, and chitosan, polycaporlactone (PCL), and poly (ethylene glycol) (PEG) were used as encapsulation materials. The major processing parameters such as the conductivity of spraying liquids, flow rate, the distance of electrical potential gradient, etc were measured to obtain the maximum efficiency. In the chitosan systems, mean particles size decreases as flow rate and the distance between nozzle and the collecting part decreases. In the uniaxial technique of the PCL systems, mean particles size decreases as flow rate decreases. In the coaxial technique of the PCL systems, it was found that the particles size gets larger under the application of the higher ratio of inner-to-outer liquid flow rates. The primary particles formed out of an electrospraying nozzle showed narrow particle size distribution, but once they arrived to the collecting part, aggregation behavior was observed obviously. Efficient nano-encapsulation of albumin with PCL, PEG, and chitosan was conveniently achieved using electrospraying at above 12 kV.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.150-150
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• 2016

디스플레이, 센서 등 전자소자는 소형화 단계를 지나 인체 부착형 소자로의 발전을 요구하고 있다. 부착형 소자에서는 접착력과 큰 마찰력이 필요하지만 마찰특성이 더 중요하므로 인체 및 물체의 마찰을 위해서는 다양한 표면에 대항하는 마찰 특성과 내구성이 요구되며 이를 위해 개코도마뱀 또는 딱정벌레, 말벌날개와 같은 자연모사형 건식 마찰 방식에 대한 연구가 활발히 진행되고 있다. 그러나 기존 폴리머를 이용하여 자연모사형 마이크로/나노 구조 형성은 기계적으로 가공된 금형 몰딩을 통한 매무 복잡한 공정을 요구된다. 본 연구에서는 이러한 복잡한 공정을 통한 마찰재 제작을 단순화하기 위해서 플라즈마 표면처리를 활용하여 나노구조 형성하는 방법을 소개하고자 하며, 건식 접착 및 마찰용 폴리머 소재(PDMS(Poly dimethyl siloxane))에 따른 표면구조 변화와 표면에너지 및 화학결합 변화에 대한 연구를 수행하였다. 플라즈마 표면처리를 위해서 자체 개발한 선형이온소스를 활용하였으며 입사에너지에 따라 표면형상 변화를 주사전자현미경을 활용하여 관찰하였다. 표면에너지 변화는 접촉각측정기를 활용하였으며, Tribology tester(Ball on disk)를 활용하여 마찰특성을 평가하였다. PDMS(Poly dimethyl siloxane)는 입사에너지가 증가함에 따라 주름형태 구조 크기가 증가하는 것을 관찰하였고, 플라즈마 처리를 통해 표면에너지 및 마찰력 증가를 관찰하였다. 그리고 플라즈마 처리 후 표면에너지 변화인 FOTS(Trichloro-(1H,1H,2H,2H- perfluorooctyl) silane) 처리를 통하여 표면에너지 감소와 마찰력이 절반으로 감소하였다. 본 연구 결과는 나노구조에 따라 표면형상 및 표면에너지 변화에 따른 PDMS의 마찰력 변화를 확인하였고, 이러한 특성을 활용하여 마찰재와 피부 부착형 접착 패치에 응용이 가능할 것으로 기대된다.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.538-545
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• 2009

The principle and application of a scanning probe microscopy(SPM) are reviewed briefly, and a low-invasive single cell manipulation and a gene delivery technique using an etched atomic force microscopy(AFM) probe tip, which we call a nanoneedle, are explained in detail. The nanoneedle insertion into a cell can be judged by a sudden drop of force in a force-distance curve. The probabilities of nanoneedle insertion into cells were 80~90%, which were higher than those of typical microinjection capillaries. When the diameter of the nanoneedle was smaller than 400 nm, the nanoneedle insertion into a cell over 1 hour had almost no influence on the cell viability. A highly efficient gene delivery and a high ratio of expressed gene per delivered DNA compared the conventional major nonviral gene delivery methods could be achieved using the gene modified nanoneedle.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.25 no.5
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• pp.368-372
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• 2016

In this study, we develop a novel high-throughput micronanopatterning system that can implement continuous mechanical pattern inscribing on flexible substrates using a rigid grating mold edge. We perform a conceptual design of the process principle, specific modeling, and buildup of a real system prototype. This research also carefully addresses several important issues related to processing and controlling, including precision motion, alignment, heating, and sensing to enable a successful micronanopatterning in a continuous and high-speed fashion. Various micronanopatterns with the desired profiles can be created by tuning the mold shape, temperature, force, and substrate material toward many potential applications involving electronics, photonics, displays, light sources, and sensors, which typically require a large-area and flexible configurations.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.993-998
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• 2002

Ultra precision processing technology is the field which is seriously protected its technology by advanced nations. Because of this reason, this technology is very difficult to supply for domestic companies, also domestic companies are revealed the limit of technology development by itself. And then, those are depend on the technology development of advanced nation, domestic companies are not conquer application step with already developed parts. Of course, some cases of its research are succeed. those are included element technology, system technology and so on, for development of ultra precision processing system. To conquer technology holding ultra precision processing accuracy of no level, active research are needed. In this paper, stability of ultra precision cutting unit is analyzed, this unit is the kernel unit in ultra precision processing machine. According to alteration of shape and material about hinge, stability investigation is performed Through this stability investigation, trial and error is reduced in design and manufacture, at the same time, we are accumulated foundation data for un it control.

• Proceedings of the Korea Information Processing Society Conference
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• 2022.05a
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• pp.477-480
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• 2022

반도체 성능 향상으로 신호를 전달하는 회로의 단위가 마이크로 미터에서 나노미터로 미세화되어 선폭(linewidth)이 점점 좁아지고 있다. 이러한 변화는 검출해야 할 불량의 크기가 작아지고, 정상 공정상태와 비정상 공정상태의 차이도 상대적으로 감소되어, 공정오차 및 공정조건의 허용범위가 축소되었음을 의미한다. 따라서 검출해야 할 이상징후 탐지가 더욱 어렵게 되어, 높은 정밀도와 해상도를 갖는 검사공정이 요구되고 있다. 이러한 이유로, 미세 공정변화를 파악할 수 있는 신규 검사 및 계측 공정이 추가되어 TAT(Turn-around Time)가 증가하게 되었고, 웨이퍼가 가공되어 완제품까지 도달하는데 필요한 공정시간이 증가하여 제조원가 상승의 원인으로 작용한다. 본 논문에서는 웨이퍼의 검계측 데이터가 아닌, 제조공정 과정에서 발생하는 다양한 센서 및 장비 데이터를 기반으로 웨이퍼 제조 결과가 양품인지 그렇지 않으면 불량인지 구별할 수 있는 가상계측 모델을 제안한다. 기계학습의 여러 알고리즘 중에서 다양한 장점을 갖는 XGBoost 알고리즘을 이용하여 예측모델을 구축하였고, 데이터 전처리(data-preprocessing), 주요변수 추출(feature selection), 모델 구축(model design), 모델 평가(model evaluation)의 순서로 연구를 수행하였다. 결과적으로 약 94% 이상의 정확성을 갖는 모형을 구축하는데 성공하였으나 더욱 높은 정확성을 확보하기 위해서는 반도체 공정과 관련된 Domain Knowledge 를 반영한 모델구축과 같은 추가적인 연구가 필요하다.

• Textile Coloration and Finishing
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• v.22 no.3
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• pp.229-238
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• 2010

Poly($\varepsilon$-caprolactone) nano/microcapsules(nmcPCL) containing phytoncide oil were synthesized by emulsion diffusion method using ethyl acetate and poly(vinyl alcohol) (PVA) as an organic solvent and an emulsion stabilizer respectively. The influence of the degree of saponofication of the PVA and the weight ratio of core to wall materials was investigated to design nanocapsules in terms of particle size, morphology, and emulsion stability. The encapsulated nmcPCL were characterized by FT-IR spectrometry, particle size analyzer and scanning electron microscope. Mean size of nanocapsules prepared with PVA with a degree of saponofication of 87% was smaller than those of PVA with a degree of saponofication of 98.5% and the mean particle size of the capsules decreased with increasing core/shell ratio.