• 폴리머
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• 제34권6호
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• pp.565-573
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• 2010

IPN 구조를 가지는 감습성 고분자 전해질로 사용하기 위하여 디브로모알칸과 가교가 가능한 copoly(2-(dimethylamino) ethyl methacrylate)(DAEMA)/butyl acrylate(BA)와 광가교가 가능한 copoly(methyl methacrylate) (MMA)/BA/2-(cinnamoyloxy)ethyl methacryate(CEMA)를 제조하였다. 전극의 기재 표면에 광조사에 의한 IPN-감습성 전해질의 부착을 위하여 3-(triethoxysilyl)propyl cinnamate(TESPC)을 전극표면에 처리하였다. IPN 구조의 감습성 고분자 필름은 copoly(DAEMA/BA), copoly(MMA/BA/CEMA) 및 1,4-dibromobutane(DBB) 가교제의 혼합 용액에 침적한 후에 UV 조사와 동시에 가열하여 제조하였다. IPN-전해질 고분자의 전극 기재와의 부착은 광화학적 $[2{\pi}+2{\pi}]$ 환화반응에 의하여 진행하였다. 얻어진 습도센서는 20~95%RH의 영역에서 매우 높은 감도와 1.5%RH 이하의 작은 히스테리시스를 보여주었다. 또한, 33~94%RH 사이에서 가습과 제습과정의 응답 및 회복 속도는 각각 48초와 65초로 나타나 매우 빠름을 알 수 있었다. 그 밖에 감습액 중의 공중합체의 농도, 가교제의 양, 가교반응 시간 등이 내수성을 포함한 감습성질에 미치는 영향을 조사하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.179-179
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• 2016

A radio-frequency (RF) Inductively Coupled Plasma (ICP) torch system was used for boron-nitride nano-tube (BNNT) synthesis. Because of electrodeless plasma generation, no electrode pollution and effective heating transfer during nano-material synthesis can be realized. For stable plasma generation, argon and nitrogen gases were injected with 60 kW grid power in the difference pressure from 200 Torr to 630 Torr. Varying hydrogen gas flow rate from 0 to 20 slpm, the electrical and optical plasma properties were investigated. Through the spectroscopic analysis of atomic argon line, hydrogen line and nitrogen molecular band, we investigated the plasma electron excitation temperature, gas temperature and electron density. Based on the plasma characterization, we performed the synthesis of BNNT by inserting 0.5~1 um hexagonal-boron nitride (h-BN) powder into the plasma. We analysis the structure characterization of BNNT by SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscopy), also grasp the ingredient of BNNT by EELS (Electron Energy Loss Spectroscopy) and Raman spectroscopy. We treated bundles of BNNT with the atmospheric pressure plasma, so that we grow the surface morphology in the water attachment of BNNT. We reduce the advancing contact angle to purity bundles of BNNT.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.495-499
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• 2010

The biocatalytic capture of $CO_2$, and its precipitationas $CaCO_3$, over bovine carbonic anhydrase (BCA) immobilized on a pore-expanded SBA-15 support was investigated. SBA-15 was synthesized using TMB as a pore expander, and the resulting porous silica was characterized by XRD, BET, IR, and FE-SEM analysis. BCA was immobilized on SBA-15 through various approaches, including covalent attachment (BCA-CA), adsorption (BCA-ADS), and cross-linked enzyme aggregation (BCA-CLEA). The immobilization of BCA on SBA-15 was confirmed by the presence of zinc metal in the EDXS analysis. The effects of pH, temperature, storage stability, and reusability on the biocatalytic performance of BCA were characterized by examining para-nitrophenyl acetate (p-NPA) hydrolysis. The $K_{cat}/K_m$ values for p-NPA hydrolysis were 740.05, 660.62, and $680.11M^{-1}s^{-1}$, respectively, where as $K_{cat}/K_m$ for free BCA was $873.76M^{-1}s^{-1}$. The amount of $CaCO_3$ precipitate was measured quantitatively using anion-selective electrode and was found to be 12.41, 11.82, or 11.28 mg $CaCO_3$/mg for BCA-CLEA, BCA-ADS, or BCA-CA, respectively. The present results indicate that the immobilized BCA-CLEA, BCA-ADS, and BCA-CA are green materials, and are tunable, reusable, and promising biocatalysts for $CO_2$ sequestration.

• 대한물리의학회지
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• 제15권2호
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• pp.49-56
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• 2020

PURPOSE: This study examined the difference in muscle activity of the trunk and legs during flat walking with or without an abdominal drawing-in maneuver. METHODS: This study was conducted on 15 healthy males and eight females who were attending D University in Busan. This experiment was conducted after 15 minutes of abdominal drawing-in training using a pressure biofeedback unit before the experiment, and the difference in the muscle activity of the trunk and legs during flat walking with or without an abdominal drawing-in technique was investigated. Surface electromyography was used, and the electrode attachment site was the right sternocleidomastoid muscle, splenius capitis muscle, rectus abdominis muscle, external abdominal oblique muscle, transverse abdominis muscle, erector spinae muscle, vastus medialis muscle, and vastus lateralis muscle (TM DTS, Noraxon, USA). The data were analyzed statistically using a paired t-test on SPSS version 18.0 (IBM). RESULTS: The muscle activity of the rectus abdominis muscle, external abdominal oblique muscle, transverse abdominis muscle, vastus medialis muscle were increased significantly and maintained more than walking without maintaining an abdominal drawing-in maneuver (p < .05). Moreover, muscle activity of the erector spinae muscle was decreased significantly and maintained more than walking without maintaining an abdominal drawing-in maneuver (p < .05). CONCLUSION: Maintaining an abdominal drawing-in maneuver during flat walking is more effective during walking training.

• Carbon letters
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• 제25권
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• pp.1-13
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• 2018

Gold functionalized graphene oxide (GOAu) nanoparticles were reinforced in acrylonitrile-butadiene rubbers (NBR) via solution and melt mixing methods. The synthesized NBR-GOAu nanocomposites have shown significant improvements in their rate of curing, mechanical strength, thermal stability and electrical properties. The homogeneous dispersion of GOAu nanoparticles in NBR has been considered responsible for the enhanced thermal conductivity, thermal stability, and mechanical properties of NBR nanocomposites. In addition, the NBR-GOAu nanocomposites were able to show a decreasing trend in their dielectric constant (${\varepsilon}^{\prime}$) and electrical resistance on straining within a range of 10-70%. The decreasing trend in ${\varepsilon}^{\prime}$ is attributed to the decrease in electrode and interfacial polarization on straining the nanocomposites. The decreasing trend in electrical resistance in the nanocomposites is likely due to the attachment of Au nanoparticles to the surface of GO sheets which act as electrical interconnects. The Au nanoparticles have been proposed to function as ball rollers in-between GO nanosheets to improve their sliding on each other and to improve contacts with neighboring GO nanosheets, especially on straining the nanocomposites. The NBR-GOAu nanocomposites have exhibited piezoelectric gauge factor (${GF_{\varepsilon}}^{\prime}$) of ~0.5, and piezo-resistive gauge factor ($GF_R$) of ~0.9 which clearly indicated that GOAu reinforced NBR nanocomposites are potentially useful in fabrication of structural, high temperature responsive, and stretchable strain-sensitive sensors.

• Journal of Electrochemical Science and Technology
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• 제2권2호
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• pp.110-115
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• 2011

The effect of $TiO_2$ nanotube (TNT) and nanoparticle (TNP) composite photoelectrode and the role of TNT to enhance the photo conversion efficiency in dye-sensitized solar cell (DSSC) have investigated in this study. Results demonstrated that the increase of the TNT content (1-15 %) into the electron collecting TNP film increases the open-circuit potential ($V_{oc}$) and short circuit current density ($J_{sc}$). Based on the impedance analysis, the increased $V_{oc}$ was attributed to the suppressed recombination between electrode and electrolyte or dye. Photochemical analysis revealed that the increased Jsc with the increased TNT content was due to the scattering effect and the reduced electron diffusion path of TNT. The highest $J_{sc}$ (12.6 mA/$cm^2$), Voc (711 mV) and conversion efficiency (5.9%) were obtained in the composite photoelectrode with 15% TNT. However, $J_{sc}$ and $V_{oc}$ was decreased for the case of 20% TNT, which results from the significant reduction of adsorbed dye amount and the poor attachment of the film on the fluorine-doped tin oxide (FTO). Therefore, application of this composite photoelectrode is expected to be a promising approach to improve the energy conversion efficiency of DSSC.

• Korean Chemical Engineering Research
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• 제55권1호
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• pp.115-120
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• 2017

현재 세계적인 이슈가 되고 있는 나노과학과 기술은 탄소나노튜브(CNTs)를 기반으로 한 바이오센서 성능 향상에 주력하고 있다. 다양한 기능성을 가진 CNTs는 높은 안정성과 바이오 수용체와 같은 생체물질과의 높은 적합성으로 이를 이용한 바이오 전극 기술에 힘입어 의학, 식품 및 환경에서 이슈가 되는 물질들을 검출하기 위한 산업적 응용 연구가 주목받고 있다. 본 연구에서는 이러한 CNTs를 이용한 전기화학적 바이오센서에 있어서 시료가 액체 상태로 검출이 예상되는데 그 시료의 화학적 특성에 따른 금 전극 사이에 고정화된 CNTs의 전자전달현상을 조사하였다. 그 결과, 시료가 극성인 경우와 무극성인 경우 고정화된 CNTs의 전자전달 현상이 다르게 나타났으며, 극성의 세기가 증가할수록 전자의 이동에 방해를 받는 것으로 확인되었다. 이는 CNTs의 양끝에 존재하는 극성 작용기와의 상호작용에 의한 것으로서 센서 디바이스 전체를 시료 용액에 침투시켜 전자이동을 관찰한 결과와 달리 안정적으로 저항값을 나타내는 것으로 확인되었다. 향후 민감도가 높은 CNTs 기반 나노바이오센서 개발 시 시료의 효과적인 전처리 공정에서 이러한 용매의 극성을 고려한 최적화 연구가 필요하다.

• 한국전기전자재료학회논문지
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• 제11권10호
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• pp.826-832
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• 1998

In this study the thin films with the structure of Si+SiO$_2$+TiN are made by RF supttering method. TiN, which has small diffusion coefficient and low resistivity, is evaporated between SiO$_2$ and Al layers. It investigates the V-R characteristics depending on the thickness of SiO$_2$ which is used as insulation layer and researches its effects on voltage stability of thin film and varistor. These films show very small resistance valus in negative(-) voltage and large and large value in positive voltage band, and with the increase of voltage, resistance value is rapidly reduced and the satisfactory characteristic of varistor is shown at +1[V]. It is found that resistance value of TiN thin film is small and also TiN thin film has more current than the thin film which is not evaporated by TiN thin film. When Al electrode is evaporated of SiO$_2$ thin film, spiking occurs, but the spiking can be prevented with evaporation of TiN between SiO$_2$ and Al layers and this thin films in made easily because of its good attachment. With the increase of voltage, the resistance is changed into non-linear pattern and the bidirectional varistor characteristic is shown and then its theory can be verified by this experiment. Accordingly, when TiN is evaporated of Si Wafer(n-100), it obtains better voltage-resistance than thin film which is not evaporated and also when varistor character is used electrically to automatic control element such as elimination of flame, power distribution arrestor and constant voltage compensation, satisfactory reproducibilities are expected.

• 폴리머
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• 제32권5호
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• pp.458-464
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• 2008

생체재생용 지지체는 높은 다공구조와 적당한 기계적인 강도를 필요로 한다. 높은 다중성과 적당한 다공크기는 지지체와 주변 환경 사이에 영양분의 공급을 원활하게 하여 셀의 지지체에 대한 초기 집착력과 성장을 가능하게 하는 구조를 제공한다. 본 논문에서는 polycaprolactone(PCL) 나노섬유를 화학 발포제와 전기방사공정을 이용하여 다양한 조건하에서 제조하였다. PCL 용액의 농도가 8wt%, 발포제의 함량 0.5wt%, 발포온도 $100^{\circ}C$ 및 체류시간 2-3초에서 가공성 측면과 다공성 측면에서 우수한 발포된 나노섬유를 얻을 수 있었다. 또한 세포의 성장성을 측정하기 위하여 인체피부세포를 셀 켤츄어링하여, 발포되지 않은 나노섬유와 비교하였다.

• Corrosion Science and Technology
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• 제20권5호
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• pp.249-255
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• 2021

In this work, we proposed a facile method to fabricate the three-dimensional porous copper current collector (3D Cu CC) for a Si-dominant anode in a Li-ion battery (LiB). The 3D Cu CC was prepared by combining chemical etching and thermal reduction from a planar copper foil. It had a porous layer employing micro-sized Cu balls with a large surface area. In particular, it had strengthened attachment of Si-dominant active material on the CC compared to a planar 2D copper foil. Moreover, the increased contact area between a Si-dominant active material and the 3D Cu could minimize contact loss of active materials from a CC. As a result of a battery test, Si-dominant active materials on 3D Cu showed higher cyclic performance and rate-capability than those on a conventional planar copper foil. Specifically, the Si electrode employing 3D Cu exhibited an areal capacity of 0.9 mAh cm^-2 at the 300^th cycles (@ 1.0 mA cm^-2), which was 5.6 times higher than that on the 2D copper foil (0.16 mAh cm^-2).