• Bulletin of the Korean Chemical Society
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• 제33권6호
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• pp.1949-1954
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• 2012

We have developed a novel and eco-friendly synthetic route for the preparation of a two-dimensional layered zinc hydroxide with intercalated nitrate anions. The layered zinc hydroxide nitrate, called 'zinc basic salt', was, in general, successfully synthesized, using an electron beam irradiation technique. The 2-propanol solutions containing hydrated zinc nitrate were directly irradiated with an electron-beam at room temperature, under atmospheric conditions, without stabilizers or base molecules. Under electron beam irradiation, the reactive OH radicals were generated by radiolysis of water molecules in precursor metal salts. After further radiolytic processes, the hydroxyl anions might be formed by the reaction of solvated electrons and the OH radical. Finally, the $Zn_5(OH)_8(NO_3)_2{\cdot}2H_2O$ was precipitated by the reaction of zinc cation and hydroxyl anions. Structure and morphology of obtained compounds were characterized by powder X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and high resolution transmission electron microscopy (HR-TEM). The chemical components of the products were determined by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis (EA). The thermal behavior of products was studied by thermogravimetric (TG) and differential thermal analysis (DTA).

• Bulletin of the Korean Chemical Society
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• 제34권6호
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• pp.1779-1782
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• 2013

N-type ZnO nanorods were grown on p-type porous silicon using a chemical bath deposition (CBD) method (p-n diode). The structure and geometry of the device were examined by field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) while the optoelectronic properties were investigated by UV/Vis absorption spectrometry as well as photoluminescence and electroluminescence measurements. The field emission (FE) properties of the device were also measured and its turn-on field and current at 6 $V/{\mu}m$ were determined. In principle, the growth of ZnO nanorods on porous siicon for optoelectronic applications is possible.

• 펄프종이기술
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• 제41권5호
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• pp.26-32
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• 2009

As a part of utilizing the nanocellulose (NC) from lignocellulosic components of wood biomass, this paper reports preliminary results on the products of sulfuric acid hydrolysis. The purpose of this study was to investigate the morphology of both NC and micro-sized cellulose fiber (MCF) isolated by acid hydrolysis from commercial microcrystalline cellulose (MCC). Field emission.scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) were employed to observe the acid hydrolysis suspension, NC, and MCF. The electron microscopy observations showed that the acid hydrolysis suspension, before separation into NC and MCF by centrifugation, was composed of nano-sized NCs and micro-sized MCFs. The morphology of isolated NCs was a whisker form of rod-like NCs. Measurements of individual NCs using TEM indicated dimensions of 6.96$\pm$0.87 nm wide by 178$\pm$55 nm long. Observations of the MCFs showed that most of the MCC particles had de-fibered into relatively long fibers with a diameter of 3-9 ${\mu}m$, depending on the degree of acid hydrolysis. These results suggest that proper technologies are required to effectively realize the potentials of both NCs and MCFs.

• Asian Journal of Atmospheric Environment
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• 제6권4호
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• pp.275-280
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• 2012

To understand the effect of aerosols on the growth and physiological conditions of trees in forests, it is important to know the state of aerosols that are deposited on the surface of the leaves or needles. In this study, we developed methods of visualization of submicron-sized aerosols that were artificially deposited from the gas-phase or liquid phase onto tree leaves or needles in trees. Firstly, we used field-emission scanning electron microscopy (FE-SEM) to observe black carbon (BC) particles that were artificially sprayed onto the leaves or needles. The distribution of BC particles deposited on the leaves and needles were distinguished based on the size and morphological features of the particles. The distribution and agglomerates size of BC particles differed between two spraying methods of BC particles employed. Secondly, we tried to visualize gold (Au) particles that were artificially sprayed onto the leaves using energy dispersive X-ray spectrometry (EDX) coupled to FE-SEM. We detected the Au particles based on the characteristic X-ray spectrum, which was secondarily generated from the Au particles. In contrast to the case of BC particles, the Au particles did not form agglomerates and were uniformly distributed on the leaf surfaces. The present results show that our methods provide useful information of adsorption and/or behavior of fine particles at the submicron level on the surface of the leaves.

• 대한화학회지
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• 제57권5호
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• pp.547-553
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• 2013

전해연마를 한 지르코늄(Zr)을 가지고 $F^-$ 이온이 함유된 무기 전해질과 유기 전해질에서 2 단계 양극산화를 진행하여 산화 지르코늄($ZrO_2$) 나노 다공성 산화막을 제조하였다. 2 단계 양극산화를 진행하면서 무기 전해질에서보다 유기 전해질에서 만들어진 지르코늄 산화막이 보다 균일한 나노 다공성 산화막을 가지게 되었다. 나노 다공성 산화막의 크기와 구조는 FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), EDS(energy dispersive spectroscopy)를 이용하여 특성을 분석하였고 형광스펙트럼을 측정하여 $ZrO_2$ 나노 다공성 산화막의 형광성을 알아보았다.

• 한국진공학회지
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• 제18권1호
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• pp.73-78
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• 2009

본 연구에서는 metal oxide chemical vapor deposition (MOCVD)을 이용하여 p형 실리콘(100) 기판 위에 30 nm 두께의 산화 아연 완충층을 $500^{\circ}C$ 에서 증착 시킨 후, 그 위에 산화 아연 나노로드를 수열합성법을 이용하여 성장시켰다. 그리고 산화아연 나노로드 성장 시 0.02몰${\sim}$0.5몰의 다양한 농도의 전구체를 사용함으로써 그에 따라 변화되는 산화 아연 나노로드의 배열상태, 구조적, 그리고 광학적 특성 평가를 실시하였다. 특성 평가는 FE-SEM(field emission scanning electron microscopy), XRD(X-ray diffraction), 그리고 PL(photoluminescence) 등의 분석 방법들을 통해 이루어졌다 본 연구를 통하여 전구체의 농도가 증가할수록 나노로드의 직경과 길이가 길어지며 0.3몰의 농도에서 뛰어난 광학 특성이 나타나는 것을 발견할 수 있었다.

• 마이크로전자및패키징학회지
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• 제28권4호
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• pp.79-83
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• 2021

본 연구에서는 기존의 silicon alkoxide(tetraethyl orthosilicate, TEOS)에 비해 단가가 저렴하여 상업화에 유리한 물유리를 전구체로 사용하여 계면활성제의 농도에 따라 형성되는 다양한 크기의 실리카 중공 미세구(hollow silica microsphere, HSM)를 합성하였다. 계면활성제의 농도에 따른 실리카 중공 미세구의 형성에 대한 물성을 퓨리에 분광기(Fourier transform infrared spectrometer), 접촉각 측정기(contact angle measurement), Brunauer-Emmett-Teller 및 Barrett-Joyner-Halenda 분석기와 전계방사형 주사전자현미경(field emission scanning electron microscopy)를 이용하여 분석하였다. 계면활성제를 적정량의 농도로 투입하여 porou s한 물유리 기반 실리카 중공 미세구를 제조할 경우 비표면적은 169 m²/g, 평균 입자 크기 25.3 ㎛ 및 표준편차는 6.25로 우수한 실리카 중공 미세구가 형성됨을 확인하였다.

• 대한약침학회지
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• 제25권4호
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• pp.382-389
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• 2022

Objectives: The Korean Industrial Standard (KS) for sterile acupuncture needles was established in 2009 based on research on the quality control of acupuncture needles. We aimed to determine the quality of acupuncture needles available in South Korea in 2021 by examining their surface condition and chemical composition using field-emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDS). Methods: In South Korea, there are 23 brands of acupuncture needles, and we examined 10-15 needles from each brand, resulting in a total of 285 needles. The microstructures of the needles were assessed by SEM. Using SEM images, we evaluated the acupuncture needle tips for the following defects/aspects: scratches, lumps, detached coating, bent tip, and tip sharpness. EDS was used to determine the chemical composition of the selected acupuncture needles. Results: Overall, 88.4% of 285 needles were found to have at least one type of abnormality. The most frequently observed abnormalities were scratches and dents on the surface (68.1%), followed by detached coating (63.2%), and lumps (61.8%); blunt tips were observed in about 24% of them. Of 252 needles with at least one defect, 86.9% had two or more types of defects. The ratio of the number of needles with any defect to that of needles without any defect varied among brands, ranging from 50% to 100%. Regarding foreign materials, higher proportions of Si and O were observed on the needles, indicating incomplete or detached silicone coating. Conclusion: The quality of acupuncture needles varied among brands, suggesting that further improvements can be made through various inspection methods.

• 한국산업보건학회지
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• 제19권3호
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• pp.213-232
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• 2009

This document was prepared to review and summarize the analytical methods for airborne and bulk asbestos. Basic principles, shortcomings and advantages for asbestos analytical instruments using phase contrast microscopy(PCM), polarized light microscopy(PLM), X-ray diffractometer (XRD), transmission electron microscopy(TEM), scanning electron microscopy(SEM) were reviewed. Both PCM and PLM are principal instrument for airborne and bulk asbestos analysis, respectively. If needed, analytical electron microscopy is employed to confirm asbestos identification. PCM is used originally for workplace airborne asbestos fiber and its application has been expanded to measure airborne fiber. Shortcoming of PCM is that it cannot differentiate true asbestos from non asbestos fiber form and its low resolution limit ($0.2{\sim}0.25{\mu}m$). The measurement of airborne asbestos fiber can be performed by EPA's Asbestos Hazard Emergency Response Act (AHERA) method, World Health Organization (WHO) method, International Standard Organization (ISO) 10312 method, Japan's Environmental Asbestos Monitoring method, and Standard method of Indoor Air Quality of Korea. The measurement of airborne asbestos fiber in workplace can be performed by National Institute for Occupational Safety and Health (NIOSH) 7400 method, NIOSH 7402 method, Occupational Safety and Health Administration (OSHA) ID-160 method, UK's Health and Safety Executive(HSE) Methods for the determination of hazardous substances (MDHS) 39/4 method and Korea Occupational Safety and Health Agency (KOSHA) CODE-A-1-2004 method of Korea. To analyze the bulk asbestos, stereo microscope (SM) and PLM is required by EPA -600/R-93/116 method. Most bulk asbestos can be identified by SM and PLM but one limitation of PLM is that it can not see very thin fiber (i.e., < $0.25{\mu}m$). Bulk asbestos analytical methods, including EPA-600/M4-82-020, EPA-600/R-93/116, OSHA ID-191, Laboratory approval program of New York were reviewed. Also, analytical methods for asbestos in soil, dust, water were briefly discussed. Analytical electron microscope, a transmission electron microscope equipped with selected area electron diffraction (SAED) and energy dispersive X-ray analyser(EDXA), has been known to be better to identify asbestiform than scanning electron microscope(SEM). Though there is no standard SEM procedures, SEM is known to be more suitable to analyze long, thin fiber and more cost-effective. Field emission scanning electron microscope (FE-SEM) imaging protocol was developed to identify asbestos fiber. Although many asbestos analytical methods are available, there is no method that can be applied to all type of samples. In order to detect asbestos with confidence, all advantages and disadvantages of each instrument and method for given sample should be considered.

• Carbon letters
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• 제15권3호
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• pp.192-197
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• 2014

A hierarchical pore structured novolac-type phenol based-activated carbon with micropores and mesopores was fabricated. Physical activation using a sacrificial silicon dioxide ($SiO_2$) template and chemical activation using potassium hydroxide (KOH) were employed to prepare these materials. The morphology of the well-developed pore structure was characterized using field-emission scanning electron microscopy. The novolac-type phenol-based activated carbon retained hierarchical pores (micropores and mesopores); it exhibited high Brunauer-Emmett-Teller specific surface areas and hierarchical pore size distributions. The hierarchical pore novolac-type phenol-based activated carbon was used as an electrode in electric double-layer capacitors, and the specific capacitance and the retained capacitance ratio were measured. The specific capacitances and the retained capacitance ratio were enhanced, depending on the $SiO_2$ concentration in the material. This result is attributed to the hierarchical pore structure of the novolac-type phenol-based activated carbon.