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Real-time Spectroscopic Methods for Analysis of Organic Compounds in Water
김치훈,지택수 한국광학회 2019 Current Optics and Photonics Vol.3 No.4
This paper proposes an optical system where the organic compound content in water is determined by using an ultraviolet (UV) LED (280 nm) and photodetector. The results obtained by the proposed prototype LED spectroscopy system, which includes a single photodetector and two parallel sample holders, are calculated by applying partial least square regression; the values are highly correlated with the actual concentrations of potassium hydrogen phthalate solutions, with an adjusted coefficient of determination about 0.996. Moreover, the total organic carbon values derived from the UV-Vis spectrometer of real samples (lake, river and sea water) differed little from those obtained by the LED spectroscopy. We confirm that the fast, sensitive, and compact LED sensor system can be readily configured for real-time monitoring of organic compounds in water.
윤대한,Vaibhav. C. Lokhande,지택수 대한전자공학회 2023 전자공학회논문지 Vol.60 No.5
This study examines the electrode material of a supercapacitor using a transition metal oxide as pseudo-capacitors. Precursors of tungsten (W), niobium (Nb), molybdenum (Mo) and iron(Fe) were mixed to synthesize them using hydrothermal synthesis method, and electrochemical properties were analyzed by depositing them on carbon cloth. In a 1M H2SO4 electrolyte, specific capacity was calculated by evaluating electrochemical characteristics through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). In addition, properties of sample materials were analyzed through X-ray diffraction analysis (XRD) and X-ray spectroscopy (XPS), and through Field emission scanning electron microscope (FE-SEM) images. As a result of the analysis, Fe did not participate in the binding, and it was found that WO3, Nb2O5, and MoO3 accounted for 18.32%, 6.94%, and 74.74% respectively, through XRF analysis. The specific capacitance was calculated through GCD and it showed a good value 375A/g in 1A/g of current density. 본 논문에서는 유사커패시터 중에서 전이금속 산화물을 이용한 슈퍼커패시터의 전극 물질을 합성하고 전기화학적 분석을 통해 그 특성을 연구하였다. 텅스텐(W)과 나이오븀(Nb), 몰리브덴(Mo)과 철(Fe)의 전구체들을 혼합하여 수열합성법(Hydrothermal Synthesis)을 이용하여 합성하였고 탄소 섬유(Carbon cloth)에 증착시켜 전기화학적 특성을 분석하였다. 1M H2SO4 전해질에서 순환전압전류법(CV, Cyclic voltametry)과 정전류 충방전법(GCD, Galvanostatic charge-discharge)을 통하여 전기화학적 특성 평가를 하여 비축전량(Specific capacitance)을 계산하였으며, X-ray 회절분석(XRD), X-ray 분광분석(XPS) 및 전기주사현미경(FE-SEM) 이미지를 통하여 각 물질의 특성을 분석하였다. 분석결과 4가지 원소 중 Fe는 결합에 참여하지 않았다는 것을 알 수 있었고 X-ray 형광분석(XRF)을 통해, 합성된 시료물질은 WO3, Nb2O5, MoO3가 각각 18.32%, 6.94%, 74.74%를 차지하고 있다는 것을 알 수 있었다. GCD를 통해 계산한 비축전량은 1A/g에서 375A/g으로 양호한 값을 나타내었다.
Myung Sang Kim,지택수,Jeongwoo Hwang,신재철 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.3
Semiconductor nanotube structures have attracted much interest for building blocks of futurenanoscale electronic and optical devices. Here, we investigate the structural properties of straininducedself-rolled III-V semiconductor nanotubes. The III-V semiconductor structures for nanotubeformation were grown on InP substrates. The bilayer and the quantum-well structuresare grown using a metalorganic chemical-vapor deposition system and were fabricated into selfrollednanotubes. For the self-rolling process, ternary InxGa1−xAs layers were used to produce alattice-mismatch strain in the nanotube membrane. The experimental observations of the nanotubestructures are discussed.
수열 합성으로 제조된 WO3 의 산용액에 따른 슈퍼축전기 전극 특성 연구
김치훈,LOKHANDE VAIBHAV CHANDRAKANT,고수정,지택수 한국물리학회 2019 새물리 Vol.69 No.2
In this study, the synthesis of WO3 using different acids was carried out to test its electrochemical performance and applicability in electrochemical charge storage devices like supercapacitors. Hydrochloric acid (W1), sulfuric acid (W2) and nitric acid (W3) were used to synthesize WO3, which was deposited on a carbon cloth substrate via a hydrothermal route. X-ray diffraction (XRD) characterization confirmed the formation of hexagonal WO3 in all three samples. Scanning electron microscopy (SEM) was performed to analyze the morphology, size and shape of the deposited material, and different nano structures, such as nano spheres, nano rods and hexagonal platelets, were observed, which confirms the effect of different acids on the morphology, shape and size of the particle. Electrochemical characterizations using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests suggest that the samples exhibit charge-storage capability and can be utilized as active materials in energy storage devices. Sample W2 exhibits highest specific capacitance of 778 Fg1 at 5 mVs1 scan rate while W1 showed the lowest specific capacitance (500 Fg1 at 5 mVs1) of all three samples. The effect of acid on WO3 parameters and consequently its electrochemical performance has been discussed further. 본 연구에서는 세 가지의 상이한 산성용액을 변수로 제조된 WO3 의 특성을 분석하였다. 산성 용액은수열합성 공정 시 첨가되는 변수로서 염산 (W1), 황산 (W2), 질산 (W3) 을 각각 이용하였고, 제조된샘플을 바탕으로 주사전자현미경 (SEM), X-선 회절분석기(X-ray diffraction, XRD)와 전기화학적 특성테스트를 실시하였다. 염산용액과 질산용액에서 제조된 샘플에서는 6각형의 혈소판 결정과 나노 구체모양을 확인할 수 있고, 황산용액에서 제조된 샘플에서는 나노구체와 나노큐브 모양을 확인 할 수 있다. 또한 XRD 데이터는 모두 회절 피크가 육방정 결정(hexagonal phase)을 가지는 것으로 확인 되었다. 전기화학적인 특성을 분석한 결과 W2 샘플의 정전용량이 가장 높지만 (778 Fg1 at 5 mVs1) 방전용량비(rate capability) 는 상대적으로 더 낮고, W1 샘플의 방전용량비는 우수하지만 가장 낮은 정전용량 특성(500 Fg1 at 5 mVs1)을 보였다. 본 연구를 통하여 WO3 를 슈퍼축전기의 우수한 활성 물질로 적용하기위한 공정 조건별 특성을 판별하였고, 적합한 후보 물질로의 가능성을 발견하였다.