• 공업화학
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• 제32권1호
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• pp.15-19
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• 2021

본 연구에서는 타이로신이 풍부한 펩타이드, Tyr-Tyr-Gly-Tyr-Tyr (YYGYY)를 환원제 및 안정화제로 사용하여 구형의 금 나노 입자의 간단한 합성 방법을 연구하였다. 펩타이드로 둘러싸인 구형의 다결정 금 나노 입자는 UV 조사 하에서 펩타이드 및 금속 전구체의 농도를 조절하여 3~15 nm 크기로 합성되었다. 합성된 금 나노 입자의 특성을 확인하기 위하여 투과 전자 현미경(TEM), 자외선-가시광선 분광광도계(UV-Vis spectroscopy), 주사 투과 전자 현미경 및 에너지 분산 X선 분광법(STEM-EDS), 푸리에 변환 적외선 분광법(FT-IR), X선 회절 분석법(XRD)을 사용하여 분석하였다. 또한, 합성된 금 나노입자는 4-니트로페놀의 환원 반응을 통해 7.3 × 10-3 s-1의 반응속도 상수를 갖는 촉매 활성을 확인하였다.

• 한국전기전자재료학회논문지
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• 제25권10호
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• pp.811-816
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• 2012

The effect of co-sputtering condition on the structural properties of $Mg_xZn_{1-x}O$ thin films grown by RF magnetron co-sputtering system was investigated for manufacturing ZnO/MgZnO structure LED. $Mg_xZn_{1-x}O$ thin films were grown with ZnO and MgO target varying RF power. Structural properties were investigated by X-ray diffraction (XRD) and Energy dispersive spectroscopy (EDS). The ZnO thin films have sufficient crystallinity on the high RF power. As RF power of ZnO target increased, the contents of MgO in the $Mg_xZn_{1-x}O$ film decreased. LED was manufactured using ZnO/MgZnO multi-layer on p-GaN/$Al_2O_3$ substrate. Threshold voltage of multi-layer LED was appeared at 8 V, and it was luminesced at wave length of 550 nm.

• 센서학회지
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• 제23권3호
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• pp.207-210
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• 2014

$TiO_2$ oxide semiconductor is being widely studied in various applications such as photocatalyst and photosensor. Pd/$TiO_2$ gas sensor is mainly used to detect $H_2$, CO and ethanol. This study focus on increasing hydrogen detection ability of Pd/$TiO_2$ in room temperature through Al-doping. Pd/$TiO_2$ was fabricated by the hydrothermal method. Contacting to Aluminum (Al) foil led to Al doping effect in Pd/$TiO_2$ by thermal diffusion and enhanced hydrogen sensing response. $TiO_2$ nanoparticles were sized at ~30 nm of diameter from scanning electron microscope (SEM) and maintained anatase crystal structure after Al doping from X-ray diffraction analysis. Presence of Al in $TiO_2$ was confirmed by X-ray photoelectron spectroscopy at 73 eV. SEM-energy dispersive spectroscopy measurement also confirmed 2 wt% Al in Pd/$TiO_2$ bulk. The gas sensing test was performed with $O_2$, $N_2$ and $H_2$ gas ambient. Pd/Al-doped $TiO_2$ did not response $O_2$ and $N_2$ gas in vacuum except $H_2$. Finally, the normalized resistance ratio ($R_{H2on}/R_{H2off}$) of Pd/Al-doped $TiO_2$ increases about 80% compared to Pd/$TiO_2$.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.53-53
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• 2007

반도체 소자의 고집적화, 미세화 화로 인해 반도체의 동작속도를 증가시키기 위하여 Cu를 이용한 금속배선이 주목받게 되었으나, 높은 압력으로 인한 보은 Cu 영역에서 과잉 디슁 현상과 에로젼을 유도하고 반도체 웨이퍼위의 low-k 물질에 손상을 줌에 따라 메탈라인 브리징과 단락을 초래할 있어, Cu의 단락인 islands를 남김으로서 표면 결항을 제거하지 못한다는 단점을 가지고 있었다. 그래서 이러한 문제점을 해결하기 위하여 기존의 CMP에 전기화학을 결합시킴으로서 낮은 하력에서의 Cu평탄화를 달성할 수 있는 ECMP (electrochemical mechanical polishing)기술이 필요하게 되었다. 따라서 본 논문에서는 전기화학적 기계적 연마(ECMP)작용을 위해, I-V 특성 곡선을 이용하여 패시베이션 막의 active, passive, transient, trans-passive영역의 전기화학적 특성을 비교 분석하였으며, Cu막의 표면 형상을 알아보기 위해 scanning electron microscopy (SEM) 측정과 energy dispersive spectroscopy (EDS)와 X-ray Diffraction (XRD) 분석을 통해 금속 화학적 조성을 조사하였다.

• Tribology and Lubricants
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• 제37권5호
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• pp.179-188
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• 2021

Reputed for their low friction coefficient and wear protection effect, diamond-like carbon (DLC) materials are considered amongst the most important lubricant coatings for tribological applications. In this framework, this investigation aims to elucidate the effect of a few operating parameters, such as applied stress and sliding amplitude on the friction lifetime of DLC coatings. Fretting wear tests are conducted using a 12.7 mm radius counterpart of 52100 steel balls slid against a substrate of the same material coated with a 2 ㎛ thickness DLC. Approximately, 5 to 57 N force is applied, generating a maximum Hertzian contact pressure of 430 to 662 MPa, corresponding to the applied force. The coefficient of friction (CoF) generates three regimes, first a running-in period regime, followed by a steady-state evolution regime, and finally a progressive increase of the CoF reaching the steel CoF value, as an indicator of reaching the substrate. To track the wear scenario, interrupted tests are performed with analysis combining scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), 3D profilometer and micro-Raman spectroscopy. The results show two endurance values: one characterizing the coating failure (Nc₁), and the other (Nc₂) indicating the friction failure which is situated where the CoF reaches a threshold value of μ_th = 0.3 in the third regime. The Archard energy density factor is used to determine the two endurance values (Nc₁, Nc₂). Based on this approach, a master curve is established delimitating both the coating and the friction endurances.

• 한국재료학회지
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• 제32권5호
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• pp.249-257
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• 2022

Transparent thin films of pure and nickel-doped ZrO₂ are grown successfully by sol-gel dip-coating technique. The structural and optical properties according to the different annealing temperatures (300 ℃, 400 ℃ and 500 ℃) are investigated. Analysis of crystallographic properties through X-ray diffraction pattern reveals an increase in crystallite size due to increase in crystallinity with temperature. All fabricated thin films are highly-oriented along (101) planes, which enhances the increase in nickel doping. Scanning electron microscopy and energy dispersive spectroscopy are employed to confirm the homogeneity in surface morphology as well as the doping configuration of films. The extinction coefficient is found to be on the order of 10^-2, showing the surface smoothness of deposited thin films. UV-visible spectroscopy reveals a decrease in the optical band gap with the increase in annealing temperature due to the increase in crystallite size. The variation in Urbach energy and defect density with doping and the change in annealing temperature are also studied.

• 공업화학
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• 제33권6호
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• pp.574-580
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• 2022

Dendrite 형태의 구리 입자 표면을 은으로 무전해 도금을 하는 과정에서, 치환도금(displacement plating)과 화학 환원도금(reducing electroless plating)을 병용하여 다양한 silver-coated copper (Ag@Cu) 입자들을 제조하였다. Ag@Cu 입자들의 물리화학적 특성은 SEM-EDS, TGA, XPS, XRD 및 BET 등으로 분석하였으며, 환원반응에 의하여 코팅되는 은은 구리 입자 표면에 나노 입자 형태로 형성되는 것을 확인할 수 있었다. Ag@Cu 입자들을 에폭시 수지와 복합화하여 도전성 필름을 제조하고 그의 열적 안정성을 평가하였다. 치환 반응과 환원 반응의 차이가 Ag@Cu 필름의 초기 저항 및 열적 안정성에 미치는 영향에 관하여 연구하였다.

• Journal of the Korean Wood Science and Technology
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• 제42권5호
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• pp.516-522
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• 2014

Old architectural wood materials damaged by a fire were evaluated on the basis of wood species and scanning electron microscopy (SEM) observation of wood tissues in combination with energy dispersive X-ray spectroscopy (EDXS) analysis. Results of SEM observation showed that tracheid wall thickness of burned parts was very thin compared with undamaged and sound wood, and tylosoid in the resin canals disappeared after the exposure to fire. SEM-EDXS analysis indicated that carbon and oxygen peaks occurred in the original energy band, and the carbon peak was higher than that of the oxygen in the burned part. A computerized tomography was also undertaken to investigate the carbonization layer formed by fire and possible internal defects.

• Journal of Welding and Joining
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• 제31권4호
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• pp.47-53
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• 2013

SCMH2 steel is widely used in the industrial members of car and tractor. This study focused on material properties and evaluation technology of the SCMH2 steel regarding the surface treatment followed by carburizing and nitriding, by means of impact test, hardness test. and fatigue test including HCF (high cycle fatigue) and VHCF (very high cycle fatigue). Drop weight impact tester (Instron, 9250 Hv) and Cantilever type rotating-bending fatigue tester (YRB200, 3150 rpm) were used to characterize the SCMH2 standard specimen before and after carburizing/nitriding. In order to understand those effects on fatigue characteristics and material properties, the fractured surfaces were carefully observed and analyzed by SEM (scanning electron microscope) and EDS (energy-dispersive X-ray spectroscopy).

• Journal of Electrochemical Science and Technology
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• 제7권3호
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• pp.218-227
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• 2016

The light harvesting efficiency is counted as an important factor in the power conversion efficiency of DSSCs. There are two measures to improve this parameter, including enhancing the dye-loading capacity and increasing the light trapping in the photoanode structure. In this paper, these tasks are addressed by introducing a macro-porous silicon (PSi) substrate as photoanode. The effects of the novel photoanode structure on the DSSC performance have been investigated by using energy dispersive X-ray spectroscopy, photocurrent-voltage, UV-visible spectroscopy, reflectance spectroscopy, and electrochemical impedance spectroscopy measurements. The results indicated that bigger porosity percentage of the PSi structure improved the both anti-reflective/light-trapping and dye-loading capacity properties. PSi based DSSCs own higher power conversion efficiency due to its remarkable higher photocurrent, open circuit voltage, and fill factor. Percent porosity of 64%, PSi(III), resulted in nearly 50 percent increment in power conversion efficiency compared with conventional DSSC. This paper showed that PSi can be a good candidate for the improvement of light harvesting efficiency in DSSCs. Furthermore, this study can be considered a valuable reference for more investigations in the design of multifunctional devices which will profit from integrated on-chip solar power.