• 한국응용과학기술학회지
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• 제30권1호
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• pp.49-56
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• 2013

Excellent electron transport properties with enhanced light scattering ability for light harvesting have made well-ordered one dimensional $TiO_2$ nanotube(TNT) arrays an alternative candidate over $TiO_2$ nanoparticles in the area of solar energy conversion applications. The principal drawback of TNT arrays being activated only by UV light has been addressed by coupling the TNT with secondary materials which are visible light-triggered. As well as extending the absorption region of sunlight, the introduction of these foreign components is also found to influence the charge separation and electron lifetime of TNT. In this study, a novel method to fabricate the TNT-based composite photoelectrodes employing visible responsive $CuInS_2$ (CIS) nanoparticles is presented. The developed method is a square wave pulse-assisted electrochemical deposition approach to wrap the inner and outer walls of a TNT array with CIS nanoparticles. Instead of coating as a dense compact layer of CIS by a conventional non-pulsed-electrochemical deposition method, the nanoparticles pack relatively loosely to form a rough surface which increases the surface area of the composite and results in a higher degree of light scattering within the tubular channels and hence a greater chance of absorption. The excellence coverage of CIS on the tubular $TiO_2$ allows the construction of an effective heterojunction that exhibits enhanced photoelectrochemical performance.

• 마이크로전자및패키징학회지
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• 제17권4호
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• pp.83-88
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• 2010

복합전기도금은 도금 중 반응성이 없는 물질을 첨가하여 도금층 내부에 함께 존재하도록 함으로써 이루어진다. 퍼멀로이는 철과 니켈의 합금을 말하는 것으로써 높은 투자율를 나타내기 때문에 산업 여러 분야에 응용된다. 복합도금을 통해 제품의 미세경도를 향상시킬 수 있으며 이는 제품의 수명과 연관된다. 하지만 실리카 나노분말 표면의 수산화기는 표면을 수분에 취약하게 만들고 이는 나노분말의 응집을 발생시켜 균일한 도금층의 형성을 어렵게 하는 요인이 된다. 본 연구에서는 실리카 나노분말의 응집을 줄이기 위하여 첨가제의 변화, 초음파 처리 시간의 변화를 살펴보았다. 초음파 처리시간의 증가시 입자의 분산효과가 좋았고 조성의 변화가 발생하였다. 첨가제에 따라 표면 형상과 공석되는 실리카 나노입자의 함량 차이가 나타났다. 염기성 도금용액에서 sodium lauryl sulfate를 사용하였을 경우 표면이 매끄럽고 공석되는 실리카 나노분말의 양도 높았다.

• Advances in nano research
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• 제15권1호
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• pp.49-57
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• 2023

As composite materials are used in many applications, the modern world looks forward to significant progress. An overview of the application of composite fiber materials in sports equipment is provided in this article, focusing primarily on the advantages of these materials when applied to sports equipment, as well as an Analysis of the influence of sports equipment of fiber-reinforced composite material on social sports development. The present study investigated surface morphology and physical and mechanical properties of S-glass fiber epoxy composites containing Al₂O₃ nanofillers (for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%). A mechanical stirrer and ultrasonication combined the Al₂O₃ nanofiller with the matrix in varying amounts. A compression molding method was used to produce sheet composites. A first physical observation is well done, which confirms that nanoparticles are deposited on the fiber, and adhesive bonds are formed. Al₂O₃ nanofiller crystalline structure was investigated by X-ray diffraction, and its surface morphology was examined by scanning electron microscope (SEM). In the experimental test, nanofiller content was added at a rate of 1, 2, and 3% by weight, which caused a gradual decrease in void fraction by 2.851, 2.533, and 1.724%, respectively, an increase from 2.7%. The atomic bonding mechanism shows molecular bonding between nanoparticles and fibers. At temperatures between 60 ℃ and 380 ℃, Thermogravimetric Analysis (TGA) analysis shows that NPs deposition improves the thermal properties of the fibers and causes negligible weight reduction (percentage). Thermal stability of the composites was therefore presented up to 380 ℃. The Fourier Transform Infrared Spectrometer (FTIR) spectrum confirms that nanoparticles have been deposited successfully on the fiber.

• 한국응용과학기술학회지
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• 제22권3호
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• pp.281-288
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• 2005

The silica nanoparticles were used as support of catalyst, filling material, electronic assembler, thin film material, and sensor material. And, the titania nanoparticles were used as pigment, dielectric substance, sensor and photocatalyst. In this paper, the spherical composite particles of $TiO_2/SiO_2$with narrow size distribution and phase pure were synthesized by ultrasonic spray pyrolysis method from $TiOSO_4$ and colloidal silica solution. Using ultrasonic apparatus, this starting solution was vaporized to droplets, and these droplets were induced into tube furnace by carrier gas. The resulting composite powder was characterized by scanning electron microscopy, X-ray diffraction analysis, TG-DTA, in vitro sun protection factor(SPF) and BET surface area analysis.

• 공업화학
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• 제28권3호
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• pp.290-293
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• 2017

블록공중합체와 나노입자로 이루어진 박막은 많은 관심을 불러 일으켜 왔다. 그리고, 이 혼성체들의 물성과 거동을 조절하기 위해서 다양한 방법이 접근되어 왔다. 본 연구에서는, 블록 공중합체와 나노입자로 이루어진 복합체를 박막 형태로 제조한 후, 이를 전기장에 조사하여 박막 내부 구조의 변화와 거동을 살펴보고자 한다. 본 실험에서는 폴리스티렌과 폴리(2-비닐피리딘)으로 구성된 블록공중합체를 사용하였고, 영구 쌍극자를 포함하는 CdSe 나노 입자를 그 속에 도입하였다. 이를 스핀코팅을 통해 박막 형태로 제조하였고, 전기장을 조사하여 전자현미경 방법으로 내부의 구조변화를 고찰하였다. 결과적으로 도입된 나노입자는 전기장에 의해 부여된 힘에 영향을 거의 받지 않고 블록공중합체의 내부에 존재하였으며, 공중합체의 내부 미세상은 전기장의 영향을 받아 전기장 방향으로 배향하였다. 이는 향후 이종으로 구성된 나노복합체의 전기장 하에서의 거동을 파악하는 데 도움이 될 것이다.

• Structural Engineering and Mechanics
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• 제84권6호
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• pp.823-829
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• 2022

This study considered the experimental parameters (Nano-graphene oxide reinforced polycarbonate, GFRP) under low-velocity impact load and vibration analysis. The effect of nano-graphene oxide (NGO) on a polycarbonate-based composite was studied. Two test procedures were adopted to obtain experimental results, vibration analysis. The mechanical tests were performed on damaged and non-damaged specimens to determine the damaging effect on the composite specimens. After the test was carried out, the effect of NGO was measured and damping factors were ascertained experimentally. 0. 2 wt% NGO was determined as the optimum amount that best affected the Vibration Analysis. The experiments revealed that the composite's damping properties were increased by adding the nanoparticles to 0.25 wt% and decreased slightly for the specimens with the highest nanoparticles content. Cyclic sinus loading was applied at a frequency of 3.5 Hz. This paper study the frequency effect of 3.5khz frequency damage on mechanical results. Found that high frequency will worthlessly affect the fatigue life in NGO/polycarbonate composite. In 3.5 Hz frequency, it was chosen to decrease the heat by frequency. Transmission electron microscopy (TEM) micrographs were used to investigate the distribution of NGO on the polycarbonate matrix and revealed a homogeneous mixture of nano-composites and strong bonding between NGO and the polycarbonate which increased the damping properties and decreased vibration. Finally, experimental modal analysis was conducted after the high-velocity impact damage process to investigate the defect on the NGO polycarbonate composites.

• 한국산학기술학회논문지
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• 제18권2호
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• pp.711-718
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• 2017

Poly(N-vinylcarbazole) (PVK)-cellulose triacetate (CTA) 복합체를 합성하고, 필름에 기공을 형성시킨 뒤, 화학적 환원법을 통해 은 나노입자를 부착하는 것을 연구하였다. PVK-CTA 복합체는 CTA-chloroform 용액에서 iron(III) chloride를 산화제로 사용하여 N-vinylcarbazole을 중합시켜 복합체를 합성하였고, 얻어진 복합체를 습한 환경에서 휘발성용매로 적셔 수증기를 적용하여 macropore가 균일하게 형성된 구조인 Honeycomb-pattern을 형성시켰다. 이후 환원제로 Tetrathiafulvalene (TTF)와 분산제로 polyvinylpyrrolidone (PVP)를 사용하여 화학적 환원법을 이용해 은 나노입자를 Honeycomb-pattern이 형성된 복합체 표면에 부착시켰다. FT-IR과 UV-Vis spectrometer을 이용하여 복합체의 형성여부를 확인하였고, N-vinylcarbazole의 함량을 달리하여 중합한 뒤 복합체의 열 분해도를 측정하였다. Scanning electron microscope (SEM)을 통해 복합체 표면에 형성된 기공의 균일도와 부착된 은 나노입자들의 분산성을 분석하였으며, 환원제, 분산제, 전구체 용액의 농도를 달리하여 은나노입자의 분산성을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제35권9호
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• pp.2660-2664
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• 2014

A simple method of depositing titanium dioxide ($TiO_2$) nanoparticles onto graphene oxide (GO) as a catalytic support was devised for photocatalytic degradation of methylene blue (MB). Thiol groups were utilized as linkers to secure the $TiO_2$ nanoparticles. The resultant GO-supported $TiO_2$ (GO-$TiO_2$) sample was characterized by transmission electron microscopy (TEM), near-edge X-ray absorption fine structure (NEXAFS), and X-ray photoelectron spectroscopy (XPS) measurements, revealing that the anatase $TiO_2$ nanoparticles had effectively anchored to the GO surface. In the photodegradation of MB, GO-$TiO_2$ exhibited remarkably enhanced photocatalytic efficiency compared with thiolated GO and pure $TiO_2$ nanoparticles. Moreover, after five-cycle photodegradation experiment, no obvious deactivation was observed. The overall results showed that thiolated GO provides a good support substrate and, thereby, enhances the photodegradation effectiveness of the composite photocatalyst.

• Advances in concrete construction
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• 제7권1호
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• pp.51-63
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• 2019

The project focuses on the dynamic analysis of concrete beams reinforced with silica-nanoparticles under blast loading. The structure is located at two boundary conditions. The equivalent composite properties are determined using Mori-Tanak model. The structure is simulated with sinusoidal shear deformation theory. Employing nonlinear strains-displacements, stress-strain, the energy equations of beam were obtained and using Hamilton's principal, the governing equations were derived. Using differential quadrature methods (DQM) and Newmark method, the dynamic deflection of the structure is obtained. The influences of volume percent and agglomeration of silica nanoparticles, geometrical parameters of beam, boundary condition and blast load on the dynamic deflection were investigated. Results showed that with increasing volume percent of silica nanoparticles, the dynamic deflection decreases.

• 한국전기전자재료학회논문지
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• 제26권4호
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• pp.315-320
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• 2013

The composites composed of conducting polymer (MEH-PPV), CdTe nanoparticles, and multiwalled carbon nanotubes (MWNTs) were spectroscopically and electrically characterized in their thin films. The composite films were prepared by spray coating. These composites were prepared from the mixture solution of MEH-PPV and CdTe-embedded MWNTs, in which CdTe nanoparticles were electrostatically bound to MWNTs. UV/vis and PL spectra were analyzed to investigate the optical absorbance and emission of the composite films. In addition, their structural, electrochemical, and electrical properties were studied by transmission electron microscopy, cyclic voltammetry, and I-V measurement.