• Journal of the KSME
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• v.34 no.4
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• pp.239-252
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• 1994

광섬유 모재제조공정인 OVD와 VAD방식에서의 입자부착 증진을 위해서 외부에서 전기장을 가 해서 실리카입자를 대전시킨 뒤에 타겟으로 부착을 시키는 전기영동원리를 이용하는 방법을 소 개하였다. 실험에서는 디스크형 타겟을 사용하여 타겟 근방에서의 온도, 전기장분포를 측정하였고 입자부착실험을 수행했다. 그 결과 9cm 타겟에 -1.6kv가 가해\ulcorner을 때 전기영동으로 인한 부착률 증가는 열영동으로 인한 효과의 약 35%가 되었다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.4
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• pp.239-248
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• 2017

It is important to understand the dispersion and deposition characteristics of particles in the flow around a circular cylinder. The rotation of a cylinder is considered as a means to modify the particle deposition in this study. We numerically investigate the effects of the rotational speed of a cylinder and the particle Stokes number on particle dispersion and deposition as well as flow characteristics. Results show that the deposition efficiency of small particles (with the Stokes number smaller than 4) decreases significantly as the rotational speed increases. However, when the Stokes number is larger than 4, the deposition efficiency increases slightly with the rotational speed of the cylinder. Meanwhile, for a given rotational speed, the increase in the Stokes number leads to an increase in deposition efficiency and deposited area.

• Journal of Korean Society on Water Environment
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• v.20 no.6
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• pp.625-630
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• 2004

Granular media filtration is used almost universally as the last particle removal process in conventional water treatment plants. Therefore, superb particle removal efficiency is needed during this process to ensure a high quality of drinking water. However, every particle can not be removed during granular media filtration. Besides the pattern of particle attachment is different depending on physicochemical aspects of particles and suspension. Filtration experiments were performed in a laboratory-scale filter using spherical glass beads with a diameter of 0.55 mm as collectors. A single type of particle suspension (Min-U-Sil 5) and alum coagulation was used to destabilize particles. The operating conditions were similar to those of standard media filtration practice: a filtration velocity of 5 m/h. More favorable particles, i.e., particles with smaller surface charge, were well attached to the collectors especially during the early stage of filtration when zeta potential of particles and collectors are both negative. This selective attachment of the lower charged particles caused the zeta potential distribution (ZPD) of the effluent to move to a more negative range. On the other hand, the ZPDs of the effluent moved from more positive to less positive when the surface charge of particles was positive and this result was thought to be caused by ion transfer between particles and collectors.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.3
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• pp.379-386
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• 1985

본 연구에서는 부차적으로 이와 같은 광반사법의 유용성을 개발, 평가하고자 한다. 또 실험에서 벽면에 부착되는 입자는 기하학적 형상에 따라 입자주위의 유체 흐름에 지배적인 영향을 받게 되므로 실험을 통하여 입자의 기하학적 형상에 따라 변 화되는 열확산 효과의 상대적인 영향을 평가한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.501-508
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• 1987

Experimental studies of particle (TiO$\_$2/) deposition from the laminar hot gas particle flow (about 1565K) onto the cold wall surface (about 1215K-1530K) were carried out by the 'real time' laser light reflectivity method (LLRM) and the photographs of scanning electron microscope(SEM). The LLRM was used for the measurement of thermophoretic deposition rates of small particles (d$\_$p/<3.mu.m), and the photographs of SEM were used for determining what factors control the collection of particles having diameters ranging from 0.2 to 30 microns. Two phenomena are primarily responsible for transport of the particles across the laminar boundary layers and deposition: (1) particle thermophoresis (i.e. particles migration down a temperature gradient), and (2) particle inertial impaction, the former effect being especially larger factor of the particle deposition in its size over the range of 0.2 to 1 microns. And also, this study indicates that thermophoresis can be important for particles as large as 15 microns. Beyond d$\_$p/=16.mu.m, this effect diminishes and the inertial impaction is taken into account as a dominant mechanism of particle deposition. The results of present experiments found to be in close agreement with existing theories.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.55-55
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• 2011

실리카 지지체 위에 은 (silver) 나노 입자를 부착시키는 방법으로는 지지체 표면을 먼저 은입자와 친화성이 큰 amino(-NH2), mercapto(-SH), cyan(-CN) 등의 관능기로 표면처리 하는 방법이 일반적으로 사용된다. 구체적으로 설명하면 첫 단계로 지지체인 실리카입자의 표면을 아민으로 표면 처리 한다. 실리카 입자위에 부착된 아민관능기는 입자 생성의 단계에서 은 (silver) 나노 입자가 붙는 접촉점의 역할과 핵 생성 장소로서의 역할을 하게되고, 아민 관능기의 이런 역할로 실리카 입자 표면에 부착된 핵이 생장하여 입자가 됨으로써 최종적으로 은(silver) 나노 입자가 실리카 지지체위에 부착된 형태의 나노복합체가 형성된다. 분자량이 다른 PVP를 사용하여 제조한, NH2와 SH로 계면처리 된 은-실리카 나노복합체제조를 시도하였다. 사용되는 PVP의 분자량이 증가함에 따라 긴 고분자 사슬에 의하여 생성된 입체장애가 증가하게 되어, 은 핵의 성장에 대한 물리적 장벽이 증가하게 된다. 그러므로 고정화된 은 입자의 크기가 감소하게 된다. 이러한 형상은 NH2기 또는 SH기로 계면 처리된 실리카를 이용하여 제조된 은-실리카 나노복합체 입자들에서 모두 관찰되지만, SH기로 계면처리된 실리카를 사용할 경우 고정화된 은 입자의 수가 더욱 많고, 크기 역시 더욱 균일함을 알 수 있다.

• Journal of the korean Society of Automotive Engineers
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• v.11 no.5
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• pp.90-100
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• 1989

본 논문은 이상유동 시스템에 부유도니 슈트, 미분탄과 같은 고 흡수, 방사하는 입자에 의한 열 확산 현상에 대한 복사효과를 수치적으로 검토하였다. 가스, 입자유동의 지배방정식들은 오일러 관점의 two-fluid model 의 근간에서 수행되었으며, 에너지 방정식의 비선형 복사생성항은 P-1 근사방법에 의해 계산되었다. 복사효과가 증가될 때에 열확산적 입자의 벽면에 대한 부착율은 상당히 낮아짐을 보였으며 열확산 현상의 스토크스 수에 따른 효과도 고려되었다.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.115-125
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• 1992

혼합 대류 이상 유동 시스템에 부유된 슈트와 미분탄과 같은 고흡수, 방사하는 입자의 열확산적 입자이동에 대한 복사 및 부력효과를 수치적으로 검토하였다. 기체 및 입자유동의 지배방정식 들은 Euler 관점의 two-fluid model의 근간에서 수행되었으며, 에너지 보존식의 비선형 복사 생 성항은 P-1 근사방법에 의해 계산되었다. 혼합 대류 유동에서의 입자의 열확산 현상은 복사 열 전달과 커플링되며, 복사효과의 증가는 부력효과를 상대적으로 감소시켜 부력효과에 의한 입자 부착율을 완화시켰다. 복사효과가 무시될 때 Grashof 수의 증가에 따라 입자의 확산효과는 감 소되었으며, 복사효과가 함께 작용될 때 입자 부착율은 증가됨을 보였다.

• Analytical Science and Technology
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• v.29 no.3
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• pp.105-113
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• 2016

The present study investigated the immobilization of lipases on silica nanoparticles and silica-coated magnetite nanoparticles as supports with a functional group to enhance the stability of lipase. The influence of functional groups, such as the epoxy group and the amine group, on the activity and stability of immobilized lipase was also studied. The epoxy group and the amino group were introduced onto the surface of nanoparticles by glycidyl methacrylate and aminopropyl triethoxysilane, respectively. Immobilized Candida rugosa lipase on silica nanoparticles and silica-coated magnetite nanoparticles with a functional group showed slightly lower initial enzyme activities than free enzyme; however, the immobilized Candida rugosa lipase retained over 92 % of the initial activity, even after 3 times reuse. Lipase was also immobilized on the silica-coated magnetite nanoparticles by cross-linked enzyme aggregate (CLEA) using glutaraldehyde and covalent binding, respectively, were also studied. Immobilized Candida rugosa lipase on silica nanoparticles and silica-coated magnetite nanoparticles by CLEA and covalent binding showed higher enzyme activities than free enzyme, while immobilized Candida rugosa lipase retained over 73 % of the initial activity after 5 times reuse.

• Korean Chemical Engineering Research
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• v.53 no.5
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• pp.540-544
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• 2015

A bath for electrodeposition of platinum nanoparitcles on low-cost graphite substrates was developed to attach nanoparticles directly onto a substrate, and electrochemical characteristics of the electrodeposition of platinum nanoparticles were investigated. The reaction mechanism was examined by the analysis of polarization behavior. Cyclic voltammetry measurements revealed that the elecrodeposition of platinum nanoparticles was limited by mass transfer. The chronoamperometric study showed an instantaneous nucleation mechanism during the electrodeposition of platinum nanoparticles on graphite. Because graphite is much cheaper than other carbon-based substrates, the electrodeposition of platinum nanoparticles on the graphite is expected to have useful applications.