• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2000년도 춘계학술대회 논문집
• /
• pp.743-746
• /
• 2000

The removal of contaminants of silicon wafers has been investigated by various methods. Laser cleaning is the new dry cleaning technique to replace wafer wet cleaning in the near future. A dry laser cleaning uses inert gas jet to remove contaminant particles lifted off by the action of a KrF excimer laser. A laser cleaning model is developed to simulate the cleaning process and analyze the influence of contaminant particles and experimental parameters on laser cleaning efficiency. The model demonstrates that various types of submicrometer-sized particles from the front sides of silicon wafer can be efficiently removed by laser cleaning. The laser cleaning is explained by a particle adhesion model. including van der Waals forces and hydrogen bonding, and a particle removal model involving rapid thermal expansion of the substrate due to the thermoelastic effect. In addition, the experiment of wafer laser cleaning using KrF excimer laser was conducted to remove various contaminant particles.

• 정보저장시스템학회:학술대회논문집
• /
• 정보저장시스템학회 2005년도 추계학술대회 논문집
• /
• pp.179-183
• /
• 2005

Particles in the HDD can cause serious damages such as scratches and thermal asperity(TA) at the head/disk interface(HDI). Accordingly, particles cause data loss including physical and electrical damages. To improve the reliability of head-disk interface, understanding the damage characteristics at the HDI due to particle interactions is required. The materials such as $A1_2O_3$, TiC and aluminum were used in this experiment. The size and hardness of particles injected into the HDI are closely relevant to surface damage caused the data loss on the disk and head. In this paper, a variety of scratches were analyzed using scanning electron microscope(SEM) and atomic force microscope(AFM). In order to analyze defects of very small size on the disk, optical surface analyzer(OSA) was also used.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 가을 학술발표회 논문집
• /
• pp.435-442
• /
• 2000

Batch test and column test were performed to develop the design factors for permeable reactive barriers(PRBs) against ammonium and heavy metals, Clinoptilolite, a kind of natural zeolites having excellent cation exchange capacity(CEC), was choosen for the reacting materials through the ion-exchange mechanism. In the batch test, the reactivity of clinoptilolite for ammonium, lead, and copper was examined varying the initial concentration of contaminants(ammonium: 20, 40, 80 ppm, heavy metals: 10, 20, 40 ppm) and the particle size of clinoptilolites(0-0.15, 0.42-0.85, 1-1.25 mm). The reactivity is increasing as the initial concentration decrease and particle size decrease. In the column test, the permeability and the reactivity of the specimens were examined using flexible-wall permeameter. Specimens were made of clinoptilolite and Jumunjin-sand with 20 : 80 weight ratio varying particle size of clinoptilolite. The maximum permeability(1${\times}$10$\^$-4/-5${\times}$10$\^$-5/cm/s) was achieved in the specimen made of 0.42-0.85 mm clinoptilolite and sand.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2015년도 학술발표회
• /
• pp.257-257
• /
• 2015

Carbon Capture and Storage with ocean sequestration is being considered as one of the most effective option for reducing the $CO_2$ net flux from atmosphere nowadays. But it is still possible for $CO_2$ substance to leaks out from transport pipeline or from the under seabed storage sites and causing damage to ambient environment. The behavior of liquid $CO_2$ under droplet shape would be strongly affected by the presence of other contaminants such as $SO_2$ comes from processing processes. This presentation shows the behavior in the sea water of pure liquid $CO_2$ droplets as well as droplets that consist of $SO_2$ substances. The study uses computational fluid dynamic models in comparison with experimental data from other previous researchers. Droplet of liquid $CO_2$ is assumed to be released at several depths in deep ocean, with other environmental conditions are set up respectively. All calculations are conducted with many different ratio of contaminant $SO_2$ to provide fundamental data of those particles rising characteristics. The effect of contaminants on the behavior of $CO_2$ droplets would be clearly shown through the results of particle deformation, terminal rising velocity happen due to buoyancy force driving from the difference in density of $CO_2$ substance and ocean water around.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제9권4호
• /
• pp.52-61
• /
• 2004

음이온 비소와 양이온 아연 및 니켈로 오염된 토양을 산세척으로 복원하기 위해서 토양세척 파일럿 장비를 이용해서 토양의 물성과 산세척 특성 및 미세토양과 용존 오염물의 발생 특성을 고찰하였다. 비소와 아연 및 니켈의 pH $2{\sim}3$에서 산세척시 황산과 인산은 공존 경쟁 음이온의 존재로 비소의 제거 효율을 높였고, 염산은 비소, 니켈, 아연을 동시에 효율적으로 제거하였다. 세척조에서 화학적 용출은 임계체류시간 이상에서 세척 효율이 일정해졌고, 산에 의한 용출 가능한 존재형태는 교환성 및 산화물 결합과 유기성 결합형태, 그리고 부분적으로 잔류형태였다. 오염 토양의 입도에 따른 과립의 토양입자의 토양세척 효율은 높지만, 미세입자($<74{\mu}m$)는 오염물질의 농집 현상이 일어나서 제거효율이 감소했다. 또한, $<149{\mu}m$ 이하의 미세토양을 물리적 입도 분리시 전체 세척효율이 향상되었다. 따라서, 미세토양의 양이 최소가 되고 화학적 용출이 최대가 되는 세척 효율 교차지점에서 화학적 용출과 미세토양의 분리가 토양세척의 증가된 효율을 보여 주었다.

• 대한기계학회논문집B
• /
• 제38권7호
• /
• pp.595-600
• /
• 2014

충돌시 부서져 사라지는 승화성 나노 탄환입자로 표면 위에 붙어있는 고체 나노입자를 가격하는 과정에서 탄환입자로부터 목표입자로의 운동에너지 전달특성을 분자동역학 전산모사 방법을 이용하여 해석하였다. 탄환입자는 이산화탄소로 이루어져있으며 탄환의 크기, 온도 및 발사속도를 바꿔가며 전산모사를 수행하였다. 탄환입자로부터 목표입자에 전달되는 운동에너지 전달비율은 탄환 속도와 크기에 관계없이 일정하였지만 탄환의 온도에 따라 민감하게 변하였는데, 이는 온도에 따른 탄환입자의 결합력의 변화에서 기인하는 것이었다. 동일조건의 아르곤 탄환에 비하여 이산화탄소 탄환의 에너지 전달효율은 약 2 배 정도이며, 여기에서 이산화탄소 탄환의 높은 세정성능이 비롯됨을 최초로 확인하였다.

• 한국입자에어로졸학회지
• /
• 제18권3호
• /
• pp.79-86
• /
• 2022

Many commercial air purifiers currently have deployed granular activated carbon (GAC) filters for removing volatile organic compounds in the indoor air. GACs are generally used to remove gaseous contaminants in the air through adsorption by the inner surfaces of pores. In addition, airborne particles can be also filtered by the surface adsorption of the GACs, which can improve the life-time of the particulate filters. In this study, the filtration efficiency of GACs to ultrafine particles through surface adsorption was investigated at different volume flow rates by deploying a continuous particle filtration system. The polydisperse sodium chloride (NaCl) particles were generated by a set of an atomizer and a diffusion dryer, and then mixed with particle-free air at different volume flow rates. The penetration of ultrafine particles and pressure drop for each experimental condition were measured to figure out the effect of the volume flow rate on the surface adsoprtion of the GACs to particles, ~ 2 mm. The particle filtration efficiency of the GACs decreased as the volume flow rate increased from 4 to 14 lpm. However, the 5 times thicker GAC filter layer decreased the penetration of ultraparticles than a preious study. The filtration efficiency of the single granule was also higher than the previous result in the literature with smaller granule filter materials.

• 한국입자에어로졸학회지
• /
• 제18권4호
• /
• pp.129-136
• /
• 2022

The line width of circuits in semiconductor devices continues to decrease down to a few nanometers. Since nanoparticles attached to the patterned wafer surface may cause malfunction of the devices, it is crucial to remove the contaminant nanoparticles. Physical cleaning that utilizes momentum of liquid for detaching solid nanoparticles has recently been tested in place of the conventional chemical method. Dropwise impaction has been employed to increase the removal efficiency with expectation of more efficient momentum exchange. To date, most of relevant studies have been focused on drop spreading behavior on a horizontal surface in terms of maximum spreading diameters and average spreading velocity of drop. More important is the local liquid velocity at the position of nanoparticle, very near the surface, rather than the vertical average value. In addition, there are very scarce existing studies dealing with microdroplet impaction that may be desirable for minimizing pattern demage of the wafer. In this study, we investigated the local velocity distribution in spreading liquid film under various impaction conditions through the CFD simulation. Combining the numerical results with the particle removal model, we estimated an effective cleaning diameter (ECD), which is a measure of the particle removal capacity of a single drop, and presented the predicted ECD data as a function of droplet's velocity and diameter particularly when the droplets are microns in diameter.

• 한국입자에어로졸학회지
• /
• 제9권4호
• /
• pp.221-230
• /
• 2013

We demonstrated the efficacy of magnetic nanoparticles (MNPs) produced from a low grade iron ore as an adsorbent for the removal of Cr(VI), a toxic heavy metal anion present in wastewater. The adsorption of Cr(VI) by these MNPs strongly depended on the dosage of MNPs, the initial concentration of the Cr(VI) solutions, and pH. The highest Cr(VI) adsorption efficiency of 22.0 mg/g was observed at pH 2.5. The adsorption data were best fit with the Langmuir isotherm and corresponded to a pseudo-second-order kinetic model. The used adsorbent was regenerated by eluting in highly alkaline solutions. Sodium bicarbonate showed the highest desorption efficiency of 83.1% among various eluents including NaOH, $Na_2HPO_4$, and $Na_2CO_3$. Due to the high adsorption capacity, the simple magnetic separation, and the high desorption efficiency, this nano-adsorbent produced from inexpensive and abundant resources may attract the attention of the industries to apply for removing various metal anionic contaminants from wastewater.

• 한국대기환경학회지
• /
• 제20권3호
• /
• pp.411-419
• /
• 2004

Titania particles are widely used as a photocatalyst to treat various contaminants in air and water. Titania particles were formed by vapor-phase oxidation of titanium tetraisopropoxide (TTIP) in a tube furnace between 773 and 1,273 K. The effect of process variables such as furnace temperature, flow rate of carrier air, and flow rate of sheath air on powder size and phase characteristics was investigated using a scanning mobility particle sizer (SMPS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The size distribution of synthesized titania particles was characterized with mode diameter and peak concentration. The mode diameter ranging from 20 to 80 nm decreased with increasing flow rates of sheath air and carrier air, and increased with increasing furnace temperature. The peak concentration increased with increasing flow rates of sheath air and carrier air The best synthetic condition for high production rate can be derived from the experimental data set represented by mode diameter and peak concentration. The crystal structure of synthesized titania particles was found to be anatase phase, ensuring high photocatalytic potential.