• 한국분말재료학회지
• /
• 제10권4호
• /
• pp.275-280
• /
• 2003

Synthesis and characteristics of Cu nanopowder were considered by in-situ characterization method using SMPS in pulsed wire evaporation process. With increasing pressure in chamber, particle size and degree of agglomeration increased by increase of collision frequency. Also, it was found from the XRD analyses and BET measurements that crystallite size and particle size decreased with elevating applied voltage. However, SMPS measurements and TEM observation revealed the increase of particle size and degree of agglomeration with increase of applied voltage. These results suggested that particle growth and agglomeration depend on overheating factor in chamber at the early stage and thermal coagulation in filtering system during powder formation until collection.

• 한국입자에어로졸학회지
• /
• 제5권2호
• /
• pp.83-90
• /
• 2009

This paper describes a condensation-evaporation method (CEM) to produce size-controlled spherical silver nanoparticles by perturbing coagulation and coalescence processes in the gas phase. Polydisperse silver nanoparticles generated by the CEM were first introduced into a differential mobility analyzer (DMA) to select a group of silver nanoparticles with same electrical mobility, which also enables to make a group of nanoparticles with elongated structures and same projected area. These silver nanoparticles selected by the DMA were then in-situ sintered at ${\sim}600^{\circ}C$, and then they were observed to turn into spherical shaped nanoparticles by the rapid coalescence process. With the assistance of modified converging-typed quartz reactor, we can also produce the 10 times higher number concentration of silver nanoparticles compared with a general quartz reactor with uniform diameter. Finally, the spherical silver nanoparticles with 30 nm were electrostatically deposited on the surface of silicon substrate with the coverage rate of ~4%/hr. This useful preparation method of size-controlled monodisperse silver nanoparticles developed in this work can be applied to the various studies for characterizing the physical, chemical, optical, and biological properties of nanoparticles as a function of their size.

• 한국산업융합학회 논문집
• /
• 제25권3호
• /
• pp.341-347
• /
• 2022

This paper presents a comparison result of two simultaneous localization and mapping (SLAM) algorithms for navigation that have been proposed in literature. The performances of Extended Kalman Filter (EKF) SLAM under Gaussian condition, FastSLAM algorithms using Rao-Blackwellised method for particle filtering are compared in terms of accuracy of state estimations for localization of a robot and mapping of its environment. The algorithms were run using the same type of robot on indoor environment. The results show that the Particle filter based FastSLAM has the better performance in terms of accuracy of localization and mapping. The experimental results are discussed and compared.

• 대한기계학회논문집B
• /
• 제27권12호
• /
• pp.1734-1743
• /
• 2003

Aerosol generator using an electrically heated tube furnace is a stable apparatus to supply nanometer sized aerosols by using the evaporation and condensation processes. Using this method, we can generate highly concentrated polydisperse aerosols with relatively narrow size distribution. In this work, characteristics of particle size distribution, generated from a tube furnace, were experimentally investigated. We evaluated effects of several operation parameters on particle generation: temperature in the tube furnace, air flow rates through the tube, size of boat containing solid sodium chloride(NaCl). As the temperature increased, the geometric mean diameter increased and the total number concentration also increased. Dilution with air affected the size distribution of the particles due to coagulation. A smaller sized boat, which has small surface area to contact with air, brings smaller particles of narrow size distribution in comparison of that of a larger boat. Finally, we changed the electrical mobility diameter of aggregate sodium chloride particles by varying relative humidity of dilution air, and obtained non-aggregate sodium chloride particles, which are easy to generate exact monodisperse particles.

• 대한기계학회논문집B
• /
• 제24권6호
• /
• pp.753-759
• /
• 2000

Photoelectric charging is a very efficient way of charging small particles. This method can be applied to combustion measurement, electrostatic precipitator, metal separation and control of micro-contamination. To understand the photoelectric charging mechanism, particle charging of silver by exposure to ultraviolet is investigated in this study. Average charges and charge distributions are measured at various conditions, using two differential mobility analyzers, a condensation nucleus counter, and an aerosol electrometer. The silver particles are generated in a spark discharge aerosol generator. After that process, the generated particles are charged in the photoelectric charger using low-pressure mercury lamp that emits ultraviolet having wavelength 253.7 nm. The results show that ultra-fine particles are highly charged by the photoelectric charging. The average charges linearly increase with increasing particle size and the charge distribution change with particle size. These results are discussed by comparison with previous experiments and proposed equations. It is assumed that the coefficient of electron emission probability is affected by initial charge. The results also show that the charge distribution of a particle is dependent on initial charge. Single changed particle, uncharged particle and neutralized particle are compared. The differences of charge distribution in each case increase with increasing particle size.

• 대한기계학회논문집B
• /
• 제26권12호
• /
• pp.1715-1721
• /
• 2002

Numerical analysis was conducted to characterize the gas flow field and particle deposition on a horizontal freestanding semiconductor wafer under the laminar flow field at vacuum environment. In order to calculate the properties of gas, the gas was assumed to obey the ideal gas law. The particle transport mechanisms considered were convection, Brownian diffusion and gravitational settling. The averaged particle deposition velocities and their radial distributions fnr the upper surface of the wafer were calculated from the particle concentration equation in an Eulerian frame of reference for system pressures of 1 mbar~1 atm and particle sizes of 2nm~10$^4$ nm(10 ${\mu}{\textrm}{m}$). It was observed that as the system pressure decreases, the boundary layer of gas flow becomes thicker and the deposition velocities are increased over the whole range of particle size. One thing to be noted here is that the deposition velocities are increased in the diffusion dominant particle size range with decreasing system pressure, whereas the thickness of the boundary layer is larger. This contradiction is attributed to the increase of particle mechanical mobility and the consequent increase of Brownian diffusion with decreasing the system pressure. The present numerical results showed good agreement with the results of the approximate model and the available experimental data.

• 한국분말재료학회지
• /
• 제20권2호
• /
• pp.129-133
• /
• 2013

In this paper we have studied the effect of water droplet size on nano-particle size distribution using SMPS(Scanning Mobility Particle Sizer)system. It can be seen that the unknown peak at >100 nm was caused by water droplets which did not dry completely when DI water was used as a solvent in the SMPS system. Therefore, it is important to dry water droplets generated from atomizer in the SMPS system when measuring the particle size distribution using less than 100 nm nano-particles in diameter. From this study, It can be concluded that the napion was a useful material as dryer ones and using EAG(Electro Aerosol Generator) as a particle generator was the most effective in reducing the effect of water droplets.

• 반도체디스플레이기술학회지
• /
• 제5권1호
• /
• pp.45-49
• /
• 2006

In this paper, a new method that monitors the quantity of particles using ion-counter in vacuum environment is introduced. In-situ particle monitoring (ISPM) system is composed by Gerdien type ion-counter (house-made), DC power supply and electrometer. The ion-counter applied by positive voltage detects only positive charged particles. Therefore the particles to be detected should be in known charge state for further data analysis. ion-counter is installed at the exhaust line of process equipment where the pressure loss is structurally low. ISPM system performance has been verified with SMPS (Scanning Mobility Particle Sizer) system. The correlation coefficient is above 0.98 at the particle size range of $20{\sim}300nm$ in diameter with identified charge distribution under $0.1{\sim}10.0$ Torr.

• 한국진공학회지
• /
• 제16권6호
• /
• pp.468-473
• /
• 2007

본 논문에서는 저압환경에서 실시간으로 나노입자를 측정할 수 있는 PBMS(Particle Beam Mass Spectrometer)의 개발에 대해 서술하였다. 개발된 PBMS의 교정을 위해 NaCl입자를 사용하였다. DMA(Differential Mobility Analyzer)를 통해 +1가로 하전된입자를 1 lpm 발생시켜 그 중 0.086 lpm을 PBMS 입구의 오리피스를 통해 분기하여 유입시켰다. DMA와 PBMS의 전류값을 비교하여 전송효율을 측정한 결과 입자의 크기에 따라 약 50$\sim$60%를 나타내었다. 또한 DMA에서 특정한 크기의 입자를 발생시켜 PBMS로 측정하였으며 그 결과는 입자크기별 농도분포와 잘 일치함을 확인할 수 있었다.

• 센서학회지
• /
• 제10권2호
• /
• pp.118-124
• /
• 2001

입자들이 용액에 녹아있을 때 pH에 따라서 다른 zeta-potential을 가지게 되며, 이것은 입자의 분산상태에 영향을 주게 된다. NO 센서에서 $WO_3$ 입자의 크기는 감도에 큰 영향을 끼치므로 Sol-Coprecipitation법에 의한 $WO_3$ 센서 제조 시에 $WO_3$ precursor 상태에서의 pH의 영향을 알아보았다. 먼저 $WO_3$ precursor의 전기적 포텐셜을 측정하여 pH가 2에서 7로 변함에 따라 mobility가 증가하여 7일 때에 가장 큰 분산도를 가진 것을 알 수 있었고, 이는 powder 제조 후 입도 분석, 감지막의 XRD peak, 표면사진으로부터 확인 할 수 있었다. 결과적으로 감도 특성에도 영향을 끼쳐 pH=7에서 제조한 센서가 다른 pH에서 제조한 센서보다 감도가 우수한 것으로 나타났다.