STUDIES FOR THE CHARACTER OF NANO-SIZED TiO₂ PARTICLE SYNTHESIZED BY MICRO-EMULSION METHOD AND GOLD-DEPOSITED TiO₂ PARTICLE

( Hyun-pyo Jhun ),( Jae-kiel Park ),( Kyoung-chul Lee ),( Jae-eon Park ) 대한화장품학회 1996 대한화장품학회지 Vol.22 No.2

Nano-Sized TiO₂ particles with diameter between 2 and 5 nm are synthesized in Water/ Triton X-100/ n-Hexane microemuelsion. Particles show the amorphous structure and partially hydroxide form. The optical absorbance of particles appears at 250nm and band edge at 340nm. Gold metal is deposited on the surface of TiO₂ particles by reduction reaction of Au(lll) ion with sodium hypophosphite. The size of gold-deposited particles is 20nm, and the optical absorbance appears at 270nm and at 550nm. So particles show the red color. The dense precipitation is formed by aggregation in the TiO₂ nano-sized particles of about 5nm size. But the bulky precipitation is formed by agglomeration phenomena in the gold- deposited particles of 20nm size. And also gold-deposited particles is easily dispersed by being re-dispersed in PEG/Water solution. This study has compared those things measuring the SPF characteristics of the cosmetics made of the synthesized particles. If the particle size is controlled appropriately, then the SPF value will be higher, or more colorless cosmetics will be made.

High Performance Supercapacitors based on CNT/MnO₂ Nanoflake particles

황정태,권동휘,문준혁 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

We introduce CNT/MnO₂ particles for high-performance supercapacitors. We prepare the CNT particles and grow MnO₂ shell on the particle. We control the amount of MnO₂ content on the CNT particles and characterize the effect on specific capacitance. We observe the capacitance 14 times higher than that of bare CNT particles. We apply CNT / MnO₂ particles to supercapacitors. We achieve high power density, which is attributed to the contribution of the high pseudocapacitance of a compact MnO₂ nanoflake and the high electrical conductivity of CNT particles with dense packing.

산업용 클린룸 내 초미립자 가시화 시스템 개발 및 성능 검증

김용식,이은택,양기영 대한건축학회 2006 대한건축학회논문집 Vol.22 No.11

The purpose of this study was to develope and performance verification of sub-micron particle visualization system for the industrial clean room. The sub-micron particle visualization system was developed by using pulse YAG laser, CCD camera, Image intensifier, tilt lens, traverse tools and etc. Laser-camera synchronization schedule was proposed to verify the acquired sub-micron particle visualization picture. Verification tests were executed in the severly controlled clean room, vacant space of real industrial clean room, and then process line of industrial clean room which was under construction. As a result, 0.144㎛ diameter sub-micron particle was visualized for the first time in a realistic clean room condition. And the sub-micron particle visualization system was improved and enhanced to be used as a major measurement tool in the construction process of industrial clean rooms.

춘천의 가정에서 미세분진 (PM<SUB>2.5</SUB>)과 입자상 다환방향족탄화수소에 대한 계절적 노출 변동

김희갑(Hekap Kim),정경미(Kyung-Mi Jung) 환경독성보건학회 2006 환경독성보건학회지 Vol.21 No.1

Lately human exposure to fine particles smaller 2.5 ㎛ in aerodynamic diameter (PM<SUB>2.5</SUB>) has become a great concern in Korea due to their possible cause of elevated mortality, lung function decrements, and more frequent hospital admissions for asthma. This study was conducted to investigate seasonal variations of human exposure to residential PM<SUB>2.5</SUB> and particle-associated polycyclic aromatic hydrocarbons (PAHs). Ten homes in Chuncheon, Korea were visited for continuous 72 hour sampling of PM<SUB>2.5</SUB> in the living rooms using a MiniVol Portable Sampler from December 22, 2002 to November 3, 2003. During the same period, outdoor PM<SUB>2.5</SUB> samples were collected on the top of the Natural Sciences Building of Kangwon National University which is located in the middle of the ten households. Samples were analyzed for PM<SUB>2.5</SUB> mass concentrations and six selected PAHs. In two smoking homes, the highest PM<SUB>2.5</SUB> concentrations were measured ranging from 51.1 to 69.7 μg/㎥ on average in all seasons, indicating smoking is a very important contributor to the elevation of indoor particle concentrations. Seasonal comparison showed that indoor particle concentrations were higher than outdoor ones except winter. Total PAH concentrations in smoking homes were highest in winter among the seasons primarily due to low ventilation rate, followed by the outdoor site and nonsmoking homes. BaP toxic equivalents (TEQs) were calculated for five PAHs. The TEQ for smoking homes in winter was highest followed by the outdoor site in winter. It is concluded that smoking and ventilation rate are two important contributors to the elevation of indoor PM<SUB>2.5</SUB> and PAH concentrations.

실리콘 잉곳 생산 공정 중 발생하는 SiO<SUB>x</SUB> 입자의 음극재 활용 가능성에 대한 연구

김정현(Junghyun Kim),안지호(Ji Ho Ahn),김창수(Chang Su Kim),정진수(Jin Su Jung),이교우(Gyo Woo Lee) 대한기계학회 2018 대한기계학회 춘추학술대회 Vol.2018 No.12

The purpose of this study is to investigate whether SiO<SUB>x</SUB> particles generated in the silicon ingot production process can be used as anode materials for secondary batteries. The silicon vapors generated during the silicon ingot production process are discharged to the outside together with the inert gas from the growing furnace and condensed into silicon particles. There have been many reports on the recycling of sludge-type silicon particles that occur during wafer making, but no studies have been reported to utilize silicon particles in the exhaust gas. In this study, condensed silicon particles were collected and analyzed by XRD, TEM and XPS to confirm the characteristics of the particles. The particles consisted of amorphous SiO<SUB>x</SUB> nanoparticles and crystalline Si nanoparticles, and contained a small amount of carbon in crystalline SiC form. Comparing these results with other studies, it is expected that the collected particles will exhibit electrical performance as anode materials for lithium ion batteries. In the future work, to confirm the electrical characteristics of the collected particles, a charge/discharge test is scheduled, and the particle surface will be modified to improve the electrical performance.

LiFePO₄ Secondary Particle Analysis using a Simulation Tool

송지훈,박주남,( Williams Agyei Appiah ),유명현,이용민 한국공업화학회 2019 한국공업화학회 연구논문 초록집 Vol.2019 No.0

LiFePO4(LFP) is one of promising active materials for LIBs because of its strengths, high thermal stability, long cycle life and low toxicity. Generally, LFP has known as a material having low Li+ diffusion coefficient and low electric conductivity. That is why primary particles of 100 to 200 nm are aggregated to form a secondary particle of 24 um. However, there are several problems to investigate the secondary particles since limited facilities and technologies. To solve the problems, herein, we built a 3D model using Comsol Multiphysics as a simulation tool using electrochemical properties of LFP secondary particle which measured in previous studies (Munakata, K. Kanamura. et al., J. of Power Souces, 2012) and analyzed properties inside the LFP secondary particle.

Invited Lectures : Particle Size Measurements in Sub-Micron Region Using Multi-Wavelength Linearly Polarized Lights

( Mikiya Araki ),( Kotaro Oki ),( Takashi Onishi ),( Seiichi Shiga ) 한국액체미립화학회 2013 한국액체미립화학회 학술강연회 논문집 Vol.2013 No.-

Feasibility of a newly developed non-intrusive particle size measurement method in sub-micron region using multi-wavelength polarized lights is investigated, experimentally. Figure 1 shows the optical setup. Polystyrene particles are used as the test particles, which are suspended in purified water. The arithmetic mean diameters of them are varied from 0.356 to 3.00 μm, which are previously measured with a conventional method (centrifugal sedimentation method). The laser beam passes through the test particles, and the scattered lights are acquired with a digital CCD camera set in parallel and perpendicular directions to the polarization plane of the incident light. Based on the Mie`s scattering theory, the ratio of scattered lights for these two components is given as a function of the particle diameter, the refractive index, and the wavelength of the incident light. By comparing the polarization ratio calculated analytically with those obtained experimentally, the particle size can be determined, which is called polarization ratio method. The major drawback of this method is the narrow measurement range, typically up to the order of 0.1 μm, which is attributed to the complicated behavior of the polarization ratio in the Mie scattering region. In order to extend the measurement range of conventional polarization ratio methods, three kinds of He-Ne lasers, whose wavelengths are 543.5, 594.1, and 632.8 nm, are used. The polarization ratios of the scattered lights are obtained from these scattered light images, and the acquired data are compared with the analytical values. Figure 2 shows the data comparison with a conventional method. It is shown that, by use of the multiwavelength polarization ratio method, the measurement range of the particle size can be extended up to the order of 3 μm, and that the accuracy of the results lies from 0.1 % to 7.6 %, when compared with the results of a centrifugal sedimentation method.

중소도시, 대도시 및 산업지역에서 채취한 미세분진 (PM<SUB>2.5</SUB>)과 입자상 다환방향족탄화수소의 계절적인 분포 특성

김희갑(Hekap Kim),정경미(Kyung-Mi Jung),김태식(Tae-Sik Kim) 환경독성보건학회 2006 환경독성보건학회지 Vol.21 No.1

This study was conducted to investigate seasonal distributions of fine particles (PM<SUB>2.5</SUB>) and associated polycyclic aromatic hydrocarbons (PAHs) at three cities. PM<SUB>2.5</SUB> samples were collected on glass fiber filters at urban (Chuncheon), metropolitan (Seoul), and industrial complex sites (Ulsan) from September, 2002 to February, 2004 using the Andersen FH 95 Particulate Sampler. About five 24-hour samples were collected from each site per season. The filters were analyzed for mass and six selected PAHs concentrations. PM<SUB>2.5</SUB> concentrations were the highest either in winter or spring, which could be attributed to the increase of fossil fuel combustion in winter or the transport of yellow sand to the Korean peninsula from China in spring, respectively. Regional PM<SUB>2.5</SUB> concentrations were higher in the order of Seoul>Chuncheon>Ulsan without statistical difference among cities. The filters were extracted using dichloromethane in an ultrasonicator and analyzed for six PAHs (anthracene, fluoranthene, pyrene, benzo[a]anthracene, chrysene, and benzo[a]pyrene) with HPLC. Total PAHs concentrations were statistically different among seasons in each site, and the highest concentrations were observed in winter at each sampling site. For total samples collected, the median total PAHs concentrations in Chuncheon (4.6 ng/㎥) and Seoul (4.4 ng/㎥) were approximately two times higher than that in Ulsan (2.1 ng/㎥). Chrysene was a component found in the highest proportion among total PAHs at each site. Carcinogenic risks calculated based on the BaP toxic equivalency factors (TEFs) over the whole sampling period were higher in the order of Chuncheon>Seoul>Ulsan. This study suggests that the atmosphere of Chuncheon is contaminated with particulate matter and PAHs at the levels equivalent to those of Seoul and that an appropriate measure needs to be taken to mitigate human health risks from inhalation exposure to airborne fine particles.

전위 소성과 크기 종속 파손을 고려한 SiC<SUB>p</SUB>/Al2124-T4 복합재의 계층적 유한요소 모델링

서영성(Yeong Sung Suh),김용배(Yong Bae Kim) 대한기계학회 2012 大韓機械學會論文集A Vol.36 No.2

일반적으로 복합재의 강도에 대한 크기 효과는 입자강화 알루미늄 복합재 제조시, 입자와 기지재를 압밀한 후 냉각할 때 입자와 기지재 사이의 열팽창계수 차에 의하여 기지재에 펀칭되는 기하적 필수 전위와, 변형 중 입자와 기지재사이의 탄소성 강성도 차로 인해 발생하는 변형률 구배 소성으로 인한 기하적 필수 전위가 주로 영향을 미치는 것으로 알려져 있다. 본 논문에서는 이러한 두 종류의 기하적 필수 전위를 전위 소성 이론에 입각하여 강도로 환산한 후 계층적으로 입자 주위 유한요소 영역에 할당하여 동일한 체적비에서 입자의 크기에 따라 변화하는 복합재의 파손 거동을 효과적으로 예측하였다. 이 방법을 적용함으로써 구형입자의 경우 간단한 축대칭 유한요소 모델링과 실험데이터를 연계하여 입자강화 복합재의 입자 크기 의존 강도 및 파손 효과를 수월하게 예측할 수 있음을 보였다. 또한 서로 다른 입자의 체적비 및 크기에 대하여 SiC강화 알루미늄 2124-T4 복합재의 강도와 파손 거동이 분명한 차이가 있음을 보인다. The strength of particle-reinforced metal matrix composites is, in general, known to be increased by the geometrically necessary dislocations punched around a particle that form during cooling after consolidation because of coefficient of thermal expansion (CTE) mismatch between the particle and the matrix. An additional strength increase may also be observed, since another type of geometrically necessary dislocation can be formed during extensive deformation as a result of the strain gradient plasticity due to the elastic-plastic mismatch between the particle and the matrix. In this paper, the magnitudes of these two types of dislocations are calculated based on the dislocation plasticity. The dislocations are then converted to the respective strengths and allocated hierarchically to the matrix around the particle in the axisymmetric finite-element unit cell model. The proposed method is shown to be very effective by performing finite-element strength analysis of SiCp/Al2124-T4 composites that included ductile failure in the matrix and particlematrix decohesion. The predicted results for different particle sizes and volume fractions show that the length scale effect of the particle size obviously affects the strength and failure behavior of the particle-reinforced metal matrix composites.

다단 침전법에 의한 구형 BaMgAl₁₀O₁₇:Eu 형광체의 제조 및 특성

박정민,정하균,박희동,박윤창,Park, Jumg-Min,Jung, Ha-Kyun,Park, Hee-Dong,Park, Yoon-Chang 한국재료학회 2002 한국재료학회지 Vol.12 No.11

A spherical $BaMgAl_{10}$ $O_{17}$ :Eu phosphor has been synthesized by a multi-step precipitation route. In order to successfully synthesize the phosphor with spherical shape, the hydrated-alumina particles should be controlled for spherical shape. In this process, the hydroxypropyl cellulose (HPC) was used as a dispersing reagent. This reagent plays an important role in that the particles were controlled to have the uniform size of sub-micron. The final product prepared by the multi-step precipitation method maintained spherical shape with uniform size of 0.4$\mu\textrm{m}$. It can be seen in X-ray diffraction patterns, formation of the single phase of $BaMgAl_{10}$ $O_{17}$ :Eu phosphor prepared by the multi-step precipitation method at $1350^{\circ}C$. Also, the emission spectra of spherical $BaMgAl_{O}$ $10_{17}$ :Eu phosphor in the present case was compared with those of commercially-available blue phosphor under VUV (Vacuum Ultra Violet) excitation. The luminescence process of the $BaMgAl_{10}$ $O_{17}$ :Eu phosphor is characterized by the $4f^{6}$$5d^1$longrightarrow4f$^{7}$ transition (blue) of the $Eu^{2+}$ ion acting as an activating center and the maximum luminescence intensity was obtained by reduction treatment at 145$0^{\circ}C$.