• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.2 s.233
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• pp.228-231
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• 2005

In this paper, we present reusable quartz master fabricated by electron-beam lithography and dry etching process of quartz, and results of injection molding based on the reusable quartz master for the manufacturing of nano-scale information media. Since patterned structures of photoresist can be easily damaged by separation (demolding) process of nickel stamper and master, a master with photoresist cannot be reused in stamper fabrication process. In this work, we have made it possible of the repeated use of master by directly patterning on quart in nickel stamper fabrication process. We have designed and fabricated four different specimens including 100nm, 140nm 200nm and 400nm pit patterns. In addition, both intaglio and embossed carving patterns are fabricated for each specimen. In the preliminary test of injection molding, we have fabricated polycarbonate patterns with varying mold temperature. We have experimentally verified the fabrication process of the reusable quart master and possibility of quartz master as direct stamper.

• Bulletin of the Korean Chemical Society
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• v.31 no.7
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• pp.1968-1972
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• 2010

Pt-Co alloy nanowire array was directly synthesized by electrochemical deposition with polycarbonate template at -1.0V and subsequent chemical etching of the template. The use of Pt-Co alloy nanowire array-modified electrode (Pt-Co NAE) for the determination of morphine (MO) is described. The morphology of the Pt-Co alloy nanowire array has been investigated by scanning electron microscopy (SEM) and energy disperse X-ray spectroscopy (EDS) analysis), respectively. The resulting Pt-Co NAE offered a linear amperometric response for morphine ranging from $2.35\times10^{-5}$ to $2.39\times10^{-3}$ M with a detection limit of $7.83\times10^{-6}$ M at optimum conditions. This sensor displayed high sensitivity and long-term stability.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.168.1-168.1
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• 2015

자동차 산업분야에서 차량 경량화의 한 수단으로, 자동차용 유리를 무게가 가볍고 고강도 투명 고분자 소재인 폴리카보네이트로 대체하고자 하는 연구가 이루어지고 있다. 하지만, 폴리카보네이트의 낮은 내 마모 특성과 자외선에 의한 열화 및 변색 현상은 해결해야 할 문제점으로 지적되고 있다. 본 연구에서는, 폴리카보네이트의 내마모 특성을 향상시키기 위해 HIPIMS+ (High Power Impulse Magnetron Sputtering+) 방법을 이용하여 투과율이 확보되고, 고경도 특성을 갖는 Al-Si-N 박막을 증착하였다. 고속증착을 하기 위해 Target에 인가되는 Power를 올리게 되었는데, 열팽창 계수가 큰 고분자 물질인 폴리카보네이트 시료의 온도가 상승하여 증착된 박막과의 열팽창 계수 차이에 의해 박막에 Crack이 형성되는 문제가 발생하였다. 증착되는 Al-Si-N 박막의 공정 압력에 따른 Stress 제어 방법 및 폴리카보네이트 시료의 온도 상승을 막기 위한 알루미늄 구조체를 이용함으로써 박막의 Crack 형성을 억제하고자 하였다. 박막의 Stress를 확인하기 위하여 AFM (Atomic Force Microscope)과 OM (Optical Microscope)을 이용하여 분석하였고, 박막의 경도는 Knoop ${\mu}$-hardness tester를 사용하여 측정하였다. Al-Si-N 박막 경도는 Si at.%/(Al at.% + Si at.%) 비율이 16%에서 33 GPa의 경도를 갖는 것을 확인하였다. UV-Vis Spectrometer를 이용하여 투과율을 측정한 결과, 400-700 nm 파장의 가시광 영역 평균 투과율은 80%로 측정되었다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.6
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• pp.783-790
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• 2004

Adhesive-bonded joints are widely used in the industry. Recently, applications of adhesive bonding joints have been increased extensively in automobile and aircraft industry. The strength of adhesive joints is influenced by the surface roughness, adhesive shape, stress distribution, and etc. However, the magnitude of the influence has not yet been clarified because of the complexity of the phenomena. In this study, as the fundamental research of adhesive bonding joints, the effects of adhesive shape and loading speed on bonding strength properties and durability of aluminum to polycarbonate single-lap joints were studied. To evaluate the effect of adhesive shape, several modified shapes were used, and loading speeds were varied from 0.05 to 5 mm/min. As a result, the load-displacement distribution was shown a brittle fracture tendency. The trigonal edged single lap and bevelled lap joints showed the higher strength than the plain single lap, trigonal single lap, joggle lap and double lap joints in same adhesive area. The fractures of trigonal single lap and trigonal edged single lap joints that had the higher strength level were shown as the mixture type of the cohesive and interfacial-failure, mostly joggle lap joints that had the lower strength level were shown as the adhesive-failure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.6-10
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• 2001

We synthesized polypyrrole (PPy) nanotubules by oxidative polymerization of the pyrrole monomer on the pore of a polycarbonate membrane. The electrochemical behavior was investigated using cyclic voltammetry and AC impedance. The redox potential was about -0.5 V vs. Ag/AgCl reference electrode, while the potential was about 0 V for electro-synthesized PPy film. It is considered as the backbone grows according to the pore wall. Therefore, it is possible to be arranged regularly. That leads to improvement in the electron hopping. The AC impedance plot gave a hint of betterment of mass transport. PPy nanotubules have improved in mass transport, or diffusion. That is because the diffusion occurs through a thin pore wall of PPy nanotubules. The kinetic parameter of PPy nanotubules enzyme electrode with glucose solution was evaluated. The formal Michaelis constant and maximum current calculated by computer were about 23.8 mmol $dm^{-3}$ and $440\;{\mu}A$ respectively. Obviously, an affinity for the substrate and current response of the PPy nanotubules enzyme electrode are rather good, comparing with that of PPy film. What is more, the enzyme electrode is sensitive to blood sugar of a diabetic serum despite an obstruction of ascorbic acid, oxygen, some protein and/or hormone.

• Korean Journal of Materials Research
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• v.19 no.9
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• pp.499-503
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• 2009

Transparent ITO films were deposited on a polycarbonate substrate with RF magnetron sputtering in a pure argon (Ar) and oxygen ($O_2$) gas atmosphere, and then post deposition electro annealed for 20 minutes in a $4{\times}10^{-1}$ Pa vacuum. Electron bombardment with an accelerating voltage of 100 V increased the substrate temperature to $120^{\circ}C$. XRD analysis of the deposited ITO films did not show any diffraction peaks, while electro annealed films indicated the growth of crystallites on the (211), (222), and (400) planes. The sheet resistance of ITO films decreased from 103 to $82{\Omega}/\square$. The optical transmittance of ITO films in the visible wavelength region increased from 85 to 87%. Observation of the work function demonstrated that the electro-annealing increased the work function of ITO films from 4.4 to 4.6 eV. The electro annealed films demonstrated a larger figure of merit of $3.0{\times}10^{-3}{\Omega}^{-1}$ than that of as deposited films. Therefore, the electro annealed films had better optoelectrical performances than as deposited ITO films.

• Composites Research
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• v.18 no.4
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• pp.8-13
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• 2005

Rotating circular disks are widely used in data storage devices as well as in traditional industrial machines. Faster rotating speed is required in data storage devices for higher data transfer rate. In this Paper an application of composite materials to CD is proposed to increase critical speeds and the strength analysis was performed. A differential equation of displacement is derived for the analytic stress distribution of rotating polar orthotropic disk. The stress distributions for typical GFRP and CFRP disks and the maximum allowable speeds subjected to a constraint of tensile strength are presented in addition to polycarbonate disk. The results show that the application of CFRP to rotating disk can increase the maximum allowable rotating speed but this may not be applicable to GFRP disk.

• Progress in Medical Physics
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• v.1 no.1
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• pp.97-107
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• 1990

A method of detecting charged particles in an allyl diglycol carbonate material (PN-3) which is available, amorphous, optically clear and thermoset plastic in which nuclear particle tracks could be revealed by etching in hot NaOH solutions, has been investigated. It has been applied to the study of alpha particle tracks over an energy range of 3.17～5.49 MeV which has been obtained after having passed through several sheets of polycarbonate. The dose equivalent rate of the alpha source was calculated and the spark chamber was used in order to measure the range of alpha particles after having passed through different number of absorbers. The etching characteristics and the detection response of PN-3 have been studied as a funcion of lengths of etched tracks against the parameters of energies and of the track etching rate(V$_{T}$). The investigation of the etching process for alpha particles in the PN-3 provided the most interesting results.s.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.3
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• pp.307-314
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• 2009

Large area micro pattern replication has promising application potential in many areas. Rolling imprint process has been demonstrated as one of the most competitive processes for such micro pattern replication, because it has advantages in low cost, high throughput and high efficiency. In this paper, we developed a prototype of roll-to-flat(R2F) thermal imprint system for large area micro pattern replication process, which is one of the key processes in the fabrication of flexible displays. Experimental tests were conducted to evaluate the feasibility of system and the parameters' effect on the process, such as flat mold temperature, loading pressure and rolling speed. 100mm $\times$ 100mm stainless steel flat mold and commercially available polycarbonate sheets were used for the tests. The experimental results showed that the developed R2F system is suitable for fabrication of various micro devices with micro pattern over large area.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.840-847
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• 2003

The bonding of adhesive joints of adhesive joints is influenced by the surface roughness of the joining Parts. However, the magnitude of the influence has not yet been clarified because of the complexity of the phenomena. In this study, it is shown that surface treatment affects adhesive strength and durability of alumina/polycarbonate single-lap .joints, and leading speed affects tensile-shea strength of adhesive Joints. To evaluate effect of surface treatments on the adhesive strength, several surface treatment methods are used, that is, cleaning, grinding, SiC polishing and sand blasting. It is shown that an optimum value of the surface roughness exists with respect to the tensile-shea strength of adhesive joints. The adhesive strength shows linear relationship with the surface roughness and loading speed. And the mechanical removal of disturbing films of lubricants, impurities and oxides make adhesive strength increase significantly.