• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.104-109
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• 2021

Tactile sensors and integrated circuits that detect external stimuli have been developed for use in various industries. Most tactile sensors have been developed using the MEMS(micro electro-mechanical systems) process in which metal electrodes and strain sensors are applied to a silicon substrate. However, tactile sensors made of highly brittle silicon lack flexibility and are prone to damage by external forces. Flexible tactile sensors based on polydimethylsiloxane and using a multi-walled carbon nano-tube mixture as a pressure-sensitive material are currently being developed as an alternative to overcome these limitations. In this study, a manufacturing process of pressure-sensitive materials with low initial electrical resistance is developed and applied to the fabrication of flexible tactile sensors. In addition, flexible tactile sensors are developed with pressure-sensitive materials dispensed on a substrate with flexible mechanical properties. Finally, a study is conducted on the change in electrical resistance of pressure-sensitive materials according to the modulus of elasticity of the substrate.

• Korean Journal of Metals and Materials
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• v.49 no.5
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• pp.419-424
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• 2011

Carbon nanotubes (CNTs) were directly synthesized on a copper (Cu) plate as a current collector by the catalytic thermal vapor deposition method for an electric double-layer capacitor (EDLC) electrode. The diameters of vertically aligned CNTs grown on the Cu plate were 20~30 nm. From cyclic voltammetry (CV) results, the CNTs/Cu electrode showed high specific capacitance with typical profiles of EDLCs. Rectangularshaped CV curves suggested that the CNTs/Cu electrode could be an excellent candidate for an EDLC electrode. The specific capacitances were in a range of 25~75 F/g with a scan rate of 10~100 mV/s and KOH electrolyte concentration 1~6 M, and were maintained up to 1000 charge/discharge cycles due to strong adhesion between the Cu substrate and the CNTs.

• Korean Journal of Dental Materials
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• v.45 no.4
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• pp.243-256
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• 2018

The purpose of this study was to investigate the effects of the anodization and cyclic calcification treatment on the surface characteristic and bioactivity of the titanium thin sheet in order to obtain basic data for the production of bioactive titanium membrane. A $30{\times}20{\times}0.08mm$ titanium sheets were prepared, and then they were pickled for 10 seconds in the solution which was mixed with $HNO_3:HF:H_2O$ in a ratio of 12: 7: 81. The $TiO_2$ nanotube layer was formed to increase the specific surface area of the titanium, and then the cyclic calcification treatment was performed to induce precipitation of hydroxiapatite by improvement of the bioactivity. The corrosion resistance test, wettability test and immersion test in simulated body solution were conducted to investigate the effect of these surface treatments. The nanotubes formed by the anodization treatment have a dense structure in which small diameter tubes are formed between relatively large diameter tubes, and their inside was hollow and the outer walls were coupled to each other. The hydroxyapatite precipitates were well combined on the nanotubes by the penetration into the nanotube layer by successive cyclic calcification treatment, and the precipitation of hydroxyapatite tended to increase proportionally after immersion in simulated body solution as the number of cycles increased. In conclusion, it was confirmed that induction of precipitation of hydroxyapatite by cyclic calcification treatment after forming the nanotube $TiO_2$ nanotube layer on the surface of the titanium membrane can contribute to improvement of bioactivity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.1000-1002
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• 2012

The material with superior biocompatibility and physical-chemical stability is required to fabricate high sensitive biosensors. Many kinds of biomaterials have been evaluated to apply for bioindustry. Recently, carbon based diamond and graphene thin films have been focal pointed as bio applications and their possibility is partially evaluated. Diamond thin film has many advantages for electrochemical and biological applications, such as wide potential window (3.0~3.5V), low background current and chemical-physical stability. And graphene film has many advantages as biomaterial, chemical-physical stability and conductivity. In this work, we have cultured human nerve cell (SH-SY5Y) on the nanocrystalline diamond, mirocrystalline diamond, graphene film and cell culture dish. We use MTT assay to evaluate the characteristics of cell culture on the substrates. As a result, nerve cell is well cultured on the carbon based diamond and graphene films as similar as cell culture dish. We expect that carbon materials have been applied for bioindustry such as biosensors.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.36-40
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• 2012

We have developed the detection method of the resonance frequency of micro/nano mechanical resonator using optical method. The optical interferometery method enabled us to detect the displacement change of resonators within several nm scale. The micro mechanical resonator was produced by attaching a micro mechanical cantilever to a piezo ceramic. The mass of cantilever was increased by evaporating Au using electron beam evaporator and the mass variation was estimated by detecting the resonance frequency changes.

• Transactions of Materials Processing
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• v.17 no.8
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• pp.633-642
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• 2008

It's important to measure quantitative properties about thermal-nano behavior of polymer for producing high quality components using Nanoimprint lithography process. Nanoscale indents can be used to make the cells for molecular electronics and drug delivery, slots for integration into nanodevices, and defects for tailoring the structure and properties. In this study, formability of polymethylmetacrylate(PMMA) and polycarbonate(PC) were characterized Polymer has extreme variation in thermo mechanical variation during forming high temperature. Because of heating the polymer, it becomes softer than at room temperature. In this case it is particularly important to study high temperature-induced mechanical properties of polymer. Nanoindenter XP(MTS) was used to measure thermo mechanical properties of PMMA and PC. Polymer was heated by using the heating stage on NanoXP. At CSM(Continuous Stiffness Method) mode test, heating temperature was $110^{\circ}C,120^{\circ}C,130^{\circ}C,140^{\circ}C$ and $150^{\circ}C$ for PMMA, $140^{\circ}C,150^{\circ}C,160^{\circ}C,170^{\circ}C$ and $180^{\circ}C$ for PC, respectively. Maximum indentation depth was 2000nm. At basic mode test, heating temperature was $90^{\circ}C$ and $110^{\circ}C$ for PMMA, $140^{\circ}C,160^{\circ}C$ for PC. Maximum load was 10mN, 20mN and 40mN. Also indented pattern was observed by using SEM and AFM. Mechanical properties of PMMA and PC decreased when temperature increased. Decrease of mechanical properties from PMMA went down rapidly than that of PC.

• Korean Journal of Medicinal Crop Science
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• v.16 no.6
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• pp.402-408
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• 2008

This study was performed to investigate improving immune activities of natural water-soluble sulforaphane extracted from Brassica oleracea var. italica by nano encapsulation process. The nanoparticles of the sulforaphane extracted with ultrasonification process at $60^{\circ}C$ promoted human B and T cell growth, about $7{\sim}35%$ compared to the control. The secretion of IL-6 and TNF-${\alpha}$ from T cells were also enhanced as $2.6{\times}10^{-4}pg/cell$ and $2.1{\times}10^{-4} pg/cell$, respectively, by the adding nano samples. NK cell activation was improved about 8%, compare to the control in adding cultured medium of T cell added nano samples. It was also found that sulforaphane extracted from B. oleracea var. italica had highly inhibitory activity on hyaluronidase as $IC_{50}$ about $200\;{\mu}g/m{\ell}$. It can be concluded that natural water-soluble sulforaphane samples by nano-encapsulation, each size is 200 nm, extracted from B. oleracea var. italica has high immune activities through higher efficiency of bio-activation than conventional extracts.

• Journal of Surface Science and Engineering
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• v.43 no.1
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• pp.25-30
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• 2010

Titanium and titanium alloys are widely used for orthopedic and dental implants for their superior mechanical properties, low modulus, excellent corrosion resistance and good biocompatibility. In this study, corrosion behaviors of nanotube formed on the bone plate of Ti-6Al-4V alloy for dental use have been investigated. $TiO_2$ nanotubes were formed on the dental bone plates by anodization in $H_3PO_4$ containing 0.6 wt % NaF solution at $25^{\circ}C$. Electrochemical experiments were performed using a conventional three-electrode configuration with a platinum counter electrode and a saturated calomel reference electrode. Anodization was carried out using a scanning potentiostat (EG&G Co, Model 263A USA), and all experiments were conducted at room temperature. The surface morphology was observed using field emission scanning electron microscopy (FE-SEM) and energy dispersive x-ray spectroscopy(EDS). The corrosion behavior of the dental bone plates was examined using potentiodynamic test(potential range of -1500~2000 mV) in a 0.9% NaCl solution by potentiostat (EG&G Co, PARSTAT 2273. USA). The inner diameter of nanotube was about 150~180 nm with wall thickness of about 20 nm. The interspace of nanotube to nanotube was 50 nm. The passive region of the nanotube formed bone plates showed the broad range compared to non-nanotube formed bone plates. The corrosion surface of sample was covered with corrosion products.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.7 no.6
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• pp.1302-1307
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• 2006

This study describes the preparation of high-performance photocatalyst and its environmental applications. We prepared visible-light response nano-particle photocatalyst exhibiting the similar photocatalytic activity with $TiO_2$, dispersed $TiO_2$ on $SiO_2$ with an active rutile type titanium oxide prepared at low temperature. The binder and stable photocatalytic $TiO_2$ sol for photocatalytic system were also prepared. Such products were evaluated by UV/Vis spectrometer, X-ray diffraction analysis, SEM, measurement of photocatalytic activities and surface area, mechanical properties of $TiO_2$-coated surfaces. The results obtained can be applied in efficient photocatalytic systems using POF and metal plate for the purification of air.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.469-469
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• 2012

제주 지역은 대부분 지하수를 이용하고 있으며, 제주 서부지역의 경우, 지하수의 과다한 취수로 인해 지하수 하강은 물론 해수침투현상도 나타나고 있다.(제주미디어 2009.10) 제주지역의 지하수 적정 개발량은 약 97%에 이르고 있어 국지적으로는 지하수 개발이 한계에 이른 것으로 평가된다. 따라서, 농촌용수 공급을 위한 사업이 필요하며, 농업 환경 피해를 최소화할 수 있는 방안이 필요하다. 또한 농촌지역의 도시화에 따라 하수처리장의 농촌지역에도 늘어가고 있으며 이제는 농촌지역과 도시지역이 구분되지 않고 혼합되어 있는 형태로 발전하고 있기 때문에 과거의 농업활동도 변화되고 있으며, 하천에서 취수하는 용수중에서 농업용수로의 사용이 부적합한 용수가 취수되고 있다. 따라서 하수처리수의 농업용수 재이용시스템과 같이 수처리를 이용한 농업용수의 공급방안이 확대될 것으로 판단된다. 한국농어촌공사 농어촌연구원에서는 (주)필로스, (주)블루인바이로먼트엔텍과 함께 글로벌탑 환경기술개발사업의 과제를 수행하고 있으며, 본 연구를 통하여, 고내구성 고기능성의 복합막 기능이 부여된 UF/NF 분리막 소재 및 모듈을 개발하고 전기분해/오존조합에 의한 에너지 절약형 재이용수 공정기술을 개발하여, 판포하수처리장을 Test-bed로 선정하여 개발 기술을 적용하고자 한다. 제주도 한경면 판포리에 위치한 판포하수처리장은 하수재이용 사업을 통해 수처리 및 용수 공급 관로가 설치되어 있으며, 개발한 재이용수를 현지에서 공급 활용할 수 있어, 연구개발에 국한되지 않고 실증 플랜트에서 용수 사용자까지 연결이 가능하여 최적의 입지 연건을 가지고 있다. 개발될 시스템은, 유입조, ECR 반응조, AOPs, 나노버블을 이용한 막세정 시스템, UF/NF 시스템으로 공정이 설계되며, 제염처리는 물론 제주지역의 농업용수로써 안정적인 용수를 확보할 수 있는 시스템을 구축하고 있다. 본 연구개발을 통한 최종 목표는 하수처리장의 방류수 고도처리를 통해 도시, 농촌지역에 필요한 고품질 맞춤형 재이용수로 공급하고, 국내 외 하수 재이용시장으로 진출하는데 있다.