• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.05a
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• pp.513-516
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• 2008

We have replicated nanopillar arrays using injection molding process of active heating and cooling method by several peltier devices. The injection melding has a high accuracy ed good reproducibility that are essential for mass production at low cost. Conventional molding processes widely use the water-based mold heating and air cooling methods. However, in case of replication for nano-patterned structures, it caused several defects such as air-flow mark, non-fill, sticking and tearing. In this study, periodic nano-scale patterns are replicated by using injection molding with Peltier devices. Porous nano-scale patterns, which have pore diameter range from 120nm to 150nm, were fabricated by using anodizing process. Periodic nano-pore structures ( $20mm\;{\times}\;20mm$) were used as a mold stamp of injection molding. Finally, PMMA with nanopillar arrays was obtained by injection molding process. By using the Peltier devices, the temperature of locally adiabatic molds can be dramatically controlled and the quality of the molded patterns can be slightly improved.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2004.10a
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• pp.40-43
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• 2004

Stamps for microcontact processing are fabricated by casting elastomer such as PDMS on a master with a negative of the desired pattern. After curing, the PDMS stamp is peeled away from the master and exposed to a solution of ink and then dried. Transfer of the ink from the PDMS stamp to the substrate occurs during a brief contact between stamp and substrate. Generally, negative-tone masters, which are used for making positive-tone PDMS stamps, are fabricated by using photolithographic technique. The shortcomings of photolithography are a relative high-cost process and require extensive processing time and heavy capital investment to build and maintain the fabrication facilities. The goal of this study is to fabricate a negative-tone master by using Nano-indenter based patterning technique. Various sizes of V-grooves and U-groove were fabricated by using the combination of nanoscratch and HF isotropic etching technique. An achieved negative-tone structure was used as a master in the PDMS replica molding process to fabricate a positive-tone PDMS stamp.

• 한국금형공학회:학술대회논문집
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• 2008.06a
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• pp.35-38
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• 2008

A pattern master and a Ni stamper for 50nm class of patterns are fabricated through e-beam lithography and Ni electroforming process. A model pattern set is designed, which is based on unit patterns of 50nm, 100nm, 150nm and 200nm in length and 50nm in width. The e-beam process is optimized to fabricate designed patterns with some parameters including dose, accelerating voltage, focal distance and developing time. For Ni electroforming to fabricate Ni stamper, a seed layer, a conducting layer, is deposited first on the pattern master fabricated by an e-beam lithography process. Ni, Ti/Ni and Cr are first tested to find optimal seed layer process. Currently the best result is obtained when adopting Cr deposited to be 100nm thick with continuous tilting motion of the master substrate during the deposition process.

• Journal of Korea Technology Innovation Society
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• v.19 no.4
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• pp.736-767
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• 2016

Recently, the social issue about harmful effects of nano-materials including nano-products to human body and environment have been raised, which were not expected in times past. To prevent the risks of nano-materials on the environment and human body, the regulatory policies are reinforced to ensure public health in world trends. In Korea, governmental department has prepared the policy for 'National nano-safety Management Master Plan' since 2011. However, it is very hard to manage all kinds of nano-materials, due to lack of nano-safety law and a wide range of nano-technology application. This study aims to analyze the current situation of the national policy related to nano-safety management and legislation, and also review the limitation of current system to propose improvement plan for nano-safety.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.498-501
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• 2005

Photonic crystals, periodic structure with a high refractive index contrast modulation, have recently become very interesting platform for manipulation of light. The existence of a photonic bandgap, a frequency range in which propagation of light is prevented in all direction, makes photonic crystal very useful in application where spatial localization of light is required for waveguide, beam splitter, and cavity. But fabrication of 3 dimensional photonic crystal is still difficult process. a concept that has recently attracted a lot of attention is a planar photonic crystal based on a dielectric membrane, suspended in the air, and perforated with 2 dimensional lattice of hole. We show that the polymer slabs suspended in air with triangular lattice of air hole can exhibit the in-plane photonic bandgap for TE-like modes. The fabrication of Si master with pillar structure using hot embossing process was investigated for 2 dimensional low-index-contrast photonic crystal waveguide.

• KSTLE International Journal
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• v.6 no.2
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• pp.33-38
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• 2005

Submicron-scale patterns made of polymethyl methacrylate (PMMA) were fabricated on silicon-wafer using a capillarity-directed soft lithographic technique. Polyurethane acrylate (PUA) stamps (Master molds) were used to fabricate the patterns. Patterns with three different aspect ratios were fabricated by varying the holding time. The patterns fabricated were the negative replica of the master mold. The patterns so obtained were investigated for their adhesion and friction properties at nano-scale using AFM. Friction tests were conducted in the range of 0-80 nN. Glass (Borosilicate) balls of diameter 1.25 mm mounted on cantilever (Contact Mode type NPS) were used as tips. Further, micro-friction tests were performed using a ball-on-flat type micro-tribe tester, under reciprocating motion, using a soda lime ball (1 mm diameter) under a normal load of 3,000 mN. All experiments were conducted at ambient temperature ($24{\pm}1^{\circ}C$) and relative humidity ($45{\pm}5\%$). Results showed that the patterned samples exhibited superior tribological properties when compared to the silicon wafer and non-patterned sample (PMMA thin film) both at the nano and micro-scales, owing to their increased hydrophobicity and reduced real area of contact. In the case of patterns it was observed that their morphology (shape factor and size factor) was decisive in defining the real area of contact.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.4
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• pp.8-13
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• 2015

In this study, we fabricated and characterized a nanostructured surface based on a plastic injection molding with a local mold heating (LMH) system. A metal mold core with a closed packed nano convex array (CVA) was achieved by integrated engineering procedures: (1) master template fabrication by anodic aluminum oxidation (AAO), (2) nickel electroforming (NE) process, and (3) post-processing by precision machining. The nickel mold core was utilized to replicate a surface with a closed packed nano concave-array (CCA) based on injection molding using cyclic olefin copolymer (COC) as a plastic material. In particular, an LMH system was introduced to enhance transcription quality of the nano structures by delaying solidification of molten polymer near the surface of the mold core.

• Journal of Mechanical Science and Technology
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• v.15 no.1
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• pp.1-9
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• 2001

The recent spread of scaled telemanipulation into microsurgery and the nano-world increasingly requires the identification of the possible operation region as a main system specification. A teleoperation system is a complex cascaded system since the human operator, master, slave, and communication are involved bilaterally. Hence, a small time delay inside a master and slave system can be critical to the overall system stability even without communication time delay. In this paper we derive an upper bound of the scaling product of position and force by using Llewellyns unconditional stability. This bound can be used for checking the validity of the designed bilateral controller. Time delay from the sample and hold of computer control and its effects on stability of scaled teleoperation are modeled and simulated based on the transfer function of the teleoperation system. The feasible operation region in terms of position and force scaling decreases sharply as the sampling rate decreases and time delays inside the master and slave increase.

• Journal of Integrative Natural Science
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• v.3 no.3
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• pp.138-142
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• 2010

Polystyrene thin films containing Bragg structures have been successfully obtained by the removal of DBR porous silicon films from the DBR structured porous silicon/polystyrene composite film in HF/$H_2O$ mixture solution and by replicating the nano-structures of porous silicon containing Bragg structure. Polystyrene thin films containing Bragg structures displayed unique optical reflection resonances in optical reflection spectrum. This optical reflection band was resulted from the interference of reflection wavelength at Bragg structure of polystyrene thin films. The wavelength of reflection resonances could be modified by the change of Bragg structure of the master. Polystyrene thin films containing Bragg structures were flexible and maintained their optical characteristics upon bending. The Polystyrene thin films replicate the photonic features and the nanostructure of the master.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.63-63
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• 2010

나노 구조를 제작은 나노 기술을 기반으로 하는 electronics, optoelectronics, sensing, ultra display등의 여러 분야에서 이용되고 있다. 특히 나노 구조를 갖는 금속 패터닝의 경우 전자빔 리소 그래피 (electron beam lithography)나 레이저 패터닝(laser patterning)과 같은 방법들이 많이 사용되고 있다. 하지만 공정이 복잡하고 그로 인해 공정 비용이 많이 든다는 단점이 있었다. 나노 임프린트 리소그래피 기술은 master mold 표면의 나노 패턴을 가열, 가압 공정을 통해 기판 위의 고분자 레지스트 층으로 전사하는 기술이다. 이 기술은 간단한 공정을 통해 나노 패턴을 형성할 수 있는 기술이기 때용에 차세대 나노 패터닝 기술로써 각광받고 있다. 특히 이 기술은 레지스트 층과의 직접적인 접촉을 통해 나노 패턴을 형성하기 때문에 다양한 방법을 통해 기능성 나노 패턴을 직접적으로 형성할 수 있는 가능성을 지니고 있다. 본 연구는 novel meta1의 하나인 Ag 입자가 첨가된 ink solution를 master mold로부터 복제한 PDMS mold를 이용하여 다양한 구조의 나노 패턴을 만드는 방법에 대한 연구이다.