• 한국표면공학회지
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• 제51권6호
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• pp.365-371
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• 2018

1D core-shell nanostructures have attracted great attention due to their enhanced physical and chemical properties. Specifically, oriented single-crystalline $TiO_2$ nanorods or nanowires on a transparent conductive substrate would be more desirable as the building core backbone. However, a facile approach to produce such structure-based hybrids is highly demanded. In this study, a three-step hydrothermal method was developed to grow NiMn-layered double hydroxide-decorated $TiO_2$/carbon core-shell nanorod arrays on transparent conductive fluorine-doped tin oxide (FTO) substrates. XRD, SEM, TEM, XPS and Raman were used to analyze the obtained samples. The in-situ fabricated hybrid nanostructured materials are expected to be applicable for photoelectrode working in water splitting.

• 공업화학
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• 제33권5호
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• pp.523-531
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• 2022

A NiCo-metal organic framework (MOF) electrode, prepared using urea as a surfactant, was synthesized using a one-pot hydrothermal method. The addition of urea to the NiCo-MOF creates interstitial voids and an ultra-thin nanostructure in the NiCo-MOF, which improves its charge transfer performance. We obtained the optimal metal to surfactant ratio to achieve the best specific capacitance. The NiCo-MOF was employed as the working electrode material in a three-electrode system. Field emission scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy were employed to characterize the microstructures and morphologies of the composites. Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy curves were employed to quantify the electrochemical properties of the electrodes in a 6 M KOH electrolyte.

• Advances in nano research
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• 제13권5호
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• pp.437-451
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• 2022

Synthesis approaches usually affect the physical and chemical properties of ferrites. This helps ferrite materials to design them for desired applications. Some of these methods are mechanical milling, ultrasonic method, micro-emulsion, co-precipitation, thermal decomposition, hydrothermal, microwave-assisted, sol-gel, etc. These methods are extensively reviewed by taking example of ZnFe₂O₄. These methods also affect the microstructure and local structure of ferrite which ultimately affect the physical and chemical properties of ferrites. Various spectroscopic techniques such as Raman spectroscopy, Fourier Transform Infrared spectroscopy, Ultra Violet-Visible spectroscopy, Mossbauer spectroscopy, extended x-ray absorption fine structure, and electron paramagnetic resonance are found helpful to reveal this information. Hence, the basic principle and the usefulness of these techniques to find out appropriate information in ZnFe₂O₄ nanoparticles is elaborated in this review.

• 소성∙가공
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• 제33권4호
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• pp.261-269
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• 2024

This study aimed to optimize the MIL-53 metal-organic framework coatings for enhanced durability in carbon dioxide capture applications. We synthesized MIL-53 powders using a hydrothermal method and deposited them on stainless-steel substrates by spin coating at various speeds, ranging from 300 to 2,000 rpm. The microstructure, surface properties, and tribological characteristics of the coatings were analyzed systematically. The results indicated that the spin speed significantly impacted the coating uniformity and defect formation. Coatings prepared at moderate speeds of 500 to 1,000 rpm exhibited optimal thickness and density, resulting in superior wear resistance. The tribological tests revealed that the coatings prepared at 700 to 1000 rpm had the lowest wear rates. These findings offer valuable insights for the development of durable MOF-based coatings for carbon dioxide capture and other applications requiring long-term stability under mechanical stress.

• 동의생리병리학회지
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• 제21권6호
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• pp.1431-1436
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• 2007

In order to optimize the extract condition and improve physiological activity of the extract form Tricholoma matsutake, experiments related to extraction methods, totale yield, content of total soluble polysaccharide, SOD-like activity, total polyphenol amount, and volatile flavor compound and the others were carried out, results were obtained as following: Compare with traditional hydrothermal extraction method (Hot water extraction : HWEW), it illustrates that the low temperature extraction method which combines a supersonic waves and microwave (Supersonic microwave extraction : SMEW) causes of increasing the total yield, total soluble polysaccharide. As to the anti-oxident effect, SMEW method leds to increasing of the SOD-like activity, total polyphenol amount as well. Also, cytotoxic effect and growth inhibitory effect against cancer cell line are much higher in SMEW method than HWEW method, especially SMEW5 extracts treated by supersonic 15 min. and microwave 120W, 3 min. and 2 times. The main volatile flavor compound and infinitesimal volatile flavor compound both increase significantly by SMEW method. It is concluded the main components of the volatile flavor compounds extracted from Tricholoma matsutake are 1-octen-3-0l, Methyl cinnamate, 2-octeno1 et al. alcohol typies. Consequently, SMEW5 method is considered as the most effective one for anti-oxidant and is prior to any other methods. And the optimun conditions of this method are : supersonic waves (supersonic, 25KHz, 50W) 15 minutes, microwave spectroscopy (microwave, 2,450MHz, 120W) 3 minutes, and every treatment is performed once followed twice repeats.

• 자원환경지질
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• 제43권3호
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• pp.235-248
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• 2010

광물찌꺼기의 특성평가 방법의 표준화를 위하여 21개 광산을 대상으로 총 26개의 광물찌꺼기를 채취하여 광물찌꺼기의 비중, paste pH, 입도, 광물조성 및 중금속 함량을 분석하였다. 광물찌꺼기의 비중은 2.61-4.31(평균 3.04)의 범위를 보이며, 입도분포는 모래와 실트의 함량이 우세한 것으로 나타났다. 광물찌꺼기의 paste pH는 2.1-9.5의 범위를 보이는데, 정마그마광상, 스카른광상 및 열수교대광상의 경우에는 7.1-9.2, 그리고 열수맥상광상의 경우에는 2.1-9.5의 분포를 보인다. 열수맥상광상 유형은 paste pH에 따라 paste pH>7.0, 4.0

• 청정기술
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• 제20권3호
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• pp.306-313
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• 2014

나노다공성 $TiO_2$ 필름은 주로 염료감응형 태양전지의 작동전극으로 사용된다. 지금까지 염료감응형 태양전지의 광전환효율을 높이기 위해 $TiO_2$ 나노구조체에 대한 다양한 연구가 시도되어왔다. 본 연구에서는 수열합성법을 이용하여 FTO glass 위에 루타일 $TiO_2$ 나노로드를 수직적으로 성장시켰고 그 위에 아나타제 $TiO_2$ 필름을 재 합성하였다. 이 새로운 방법은 아나타제 $TiO_2$ 합성시 요구되는 시드층 합성단계를 피할 수 있었다. 밀집한 아나타제 $TiO_2$ 층은 전자생성층으로써 고안되었고 시드층 대신 합성된 루타일 $TiO_2$ 나노로드는 생성된 전자들이 FTO glass로 이동하는 통로역할을 하게 되었다. 전자이동률을 증진시키기 위해 루타일 나노로드에 $TiCl_4$ 수용액을 이용하여 표면 처리하였고 열처리 후 표면 위에 얇은 아나타제 $TiO_2$ 필름을 형성시켰다. 합성된 루타일-아나타제 $TiO_2$ 구조체의 두께는 $4.5-5.0{\mu}m$이고 셀 테스트 결과 3.94%의 광전환효율을 얻게 되었다. 이는 루타일 $TiO_2$ 나노로드 전극과 비교했을 때 광전환효율이 상당히 향상되는 것을 확인할 수 있었다.

• Journal of Electrochemical Science and Technology
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• 제8권4호
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• pp.338-343
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• 2017

Activated carbon has lower electrical conductivity and reliability than other carbonaceous materials because of the oxygen functional groups that form during the activation process. This problem can be overcome by doping the material with heteroatoms to reduce the number of oxygen functional groups. In the present study, N, F co-doped activated carbon (AC-NF) was successfully prepared by a microwave-assisted hydrothermal method, utilizing commercial activated carbon (AC-R) as the precursor and ammonium tetrafluoroborate as the single source for the co-doping of N and F. AC-NF showed improved electrical conductivity ($3.8\;S\;cm^{-1}$) with N and F contents of 0.6 and 0.1 at%, respectively. The introduction of N and F improved the performance of the pertinent supercapacitor: AC-NF exhibited an improved rate capability at current densities of $0.5-50mA\;cm^{-2}$. The rate capability was higher compared to that of raw activated carbon because N and F codoping increased the electrical conductivity of AC-NF. The developed method for the co-doping of N and F using a single source is cost-effective and yields AC-NF with excellent electrochemical properties; thus, it has promising applications in the commercialization of energy storage devices.

• 한국결정성장학회지
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• 제10권2호
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• pp.171-176
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• 2000

패각으로부터 얻어지는 고순도의 소석회와 탄산칼슘을 이용하여 인산1수소칼슘, 수산화아파타이트, 골회 및 인산3칼슘과 같은 인산칼슘계 화합물을 제조하였다. 인산2수소칼슘은 고순도의 소석회와 인산용액을 이용하여 제조하였으며, 그리고 인산1수소칼슘을 출발원료로 하여 고상반응법에 의해 골회를 제조하였고 또 수열처리법을 이용하여 수산화아파타이트를 제조하였다. 인산3칼슘의 제조는 골회와 고순도의 탄산칼슘을 혼합한 뒤 고상반응시켜 제조하였다. 본 연구에서는 이상과 같은 인산칼슘계 화합물에 대한 최적의 제고공정 및 제조 조건을 확립하였다.

• 한국재료학회지
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• 제24권12호
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• pp.700-703
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• 2014

Calcium phosphate minerals are biologically important because of their application in the fields of orthopaedics and dentistry. Herein we have tried to synthesize calcium phosphate minerals from biowaste clam shells. A simple microwave method was used to synthesize a mixture of calcium phosphate minerals such as hydroxyapatite, tri-calcium phosphate, and monetite. The microwave induces vibration of the dipole ions in the reagent. The heating and rearrangement of ions and atoms occurs during the process. The phases obtained in the final powder were ascertained by X-ray diffraction; the morphology of each sample was checked using a scanning electron microscope. We were able to obtain a mixture of calcium phosphate minerals using the microwave method; the calcined powder showed a brick like morphology, which is different from the rod shape morphology of the hydroxyapatite obtained using the hydrothermal process.