• Resources Recycling
• /
• v.23 no.6
• /
• pp.30-39
• /
• 2014

The trajectories of PCB(Printed Circuit Board) particles in the corona discharge electrostatic separation was simulated. The PCB particles are prepared by crushing bare board, which disassembled from electronic components, consist mostly of copper and FR-4(Flame Retardant Level-4) Firstly, a model was established for calculating of detachment points of PCB particles from the rotating electrode in separator. The model of detachment points was derived from equilibrium of force such as gravity force, centrifugal force, electrostatic force. The trajectories of particles after detachment was calculated by acceleration derived from time-integrating method of motion equation. In this simulation, particle size, supplied voltage, rotation speed of rotating roll electrode and angle of induction electrode were adopted as variables. While the trajectories of FR-4 particles were affected by all variables, rotation speed of rotating roll electrode was dominant variables affecting trajectories of copper particles.

• Proceedings of the Korean Institute of Resources Recycling Conference
• /
• 2005.10a
• /
• pp.240-242
• /
• 2005

본 연구에서는 생활폐기물 소각장에서 발생하고 있는 바닥재를 이용하여 각 입도에 대해 자력의 세기에 따라 철/비철선별 하였다. 자력의 세기에 따른 분리량과 분리된 산물의 철함 유량을 조사함으로써 자력 및 비철 효율을 파악하고자 하였다. 또한, 비철 선별기를 사용하여 비철 선별 효율을 조사하였다. 자력선별결과, 자력의 세기가 증가할수록 자력선별에 의해 분리량이 증가하였으나, 분리된 산물의 철함유량은 감소하는 경향을 나타내었다. 이러한 결과는 자력세기의 증가가 철회수량의 증가보다는 불순물의 혼입량을 증가시키는 것으로 생각된다. 비철의 경우, 입자크기가 커짐에 따라 분리율이 높았으며, 4.75mm이상에서는 대부분의 비철이 회수되었다.

• 한국가시화정보학회:학술대회논문집
• /
• 2007.11a
• /
• pp.55-58
• /
• 2007

To improve the conventional optical chromatography, the continuous particle separator, the cross-type optical chromatography, is fabricated using micro-channel and fiber optics. A laser beam irradiates into the liquid solution containing particles in the perpendicular to the liquid flow direction. The different sized polystyrene latex micro-spheres, $2.0\;{\mu}m\;{\pm}\;0.02\;{\mu}m$, $5.0\;{\mu}m\;{\pm}\;0.05\;{\mu}m$, and $10.0\;{\mu}m\;{\pm}\;0.09\;{\mu}m$ diameter, are separated in cross-type optical chromatography. The separated particles are delivered to down stream in the micro-channel maintaining the retention distance continuously. The measured retention distances for different sized particles well agree with theoretical predictions.

• Proceedings of the International Microelectronics And Packaging Society Conference
• /
• 2002.05a
• /
• pp.270-273
• /
• 2002

Conditioning은 CMP(Chemical Mechanical Planarization)에 필수적인 공정중의 하나이다. Conditioning의 목적은 removal rate와 uniformity를 CMP 공정 중에서 일정하게 유지시키는데 목적이 있다. 예전의 conditioning disks는 stainless steel substrate 위에 diamond 입자를 올리고 Ni전기도금을 결합시켜서 사용하였다. 그러나, CMP 공정 중에 Ni의분해로 인한 금속의 오염과 diamond abrasive의 분리로 인하여 scratch 문제가 발생하였다. 이 문제를 해결하기 위해서 ceramic substrate와 그것을 정밀 가공하는 기술을 응용함으로써 본래의 conditioning disks가 가지고 있는 diamond 입자의 분리와 metals 분해의 문제를 해결할 수 있게 되었다.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2019.05a
• /
• pp.250-250
• /
• 2019

현재 우리나라에서 이용하고 있는 소류사량 직접계측방법에는 Arnhem 소류사 채취기와 Helley-Smith 소류사 채취기 등이 있다. 하지만 이러한 방법은 현장에서 계측하기가 매우 어렵고 많은 비용과 인력, 시간이 소모되며 특히 연속적인 계측이 어려워 소류사량의 직접계측자료를 기초로 하는 연구는 거의 전무한 상태이다. 이에 대한 대안으로 최근 국내외에서는 마이크로폰을 내장한 금속관에 토사가 충돌 시 발생하는 음향데이터를 수집 및 분석하여 소류사량을 계측하는 간접계측방법 하이드로폰을 사용하고 있다. 하이드로폰 시스템의 대부분이 증폭채널방법을 사용하고 있는데 이러한 방법은 개별입자에 대한 음향특성을 반영하기에는 다양한 크기를 가지는 소류사 입자에 대한 음향신호를 하나의 임계치 기준으로 필터링 하기 때문에 한계가 있다. 즉 기존의 방법은 소류사량의 상대적인 크기만 추정할 수 있을 뿐 소류사량을 정량화할 수 없다. 따라서 본 연구는 소류사가 이동할 때 발생하는 충돌음향을 신호 처리하여 소류사량을 추정하는 계측기기인 하이드로폰을 이용하여 기존 소류사량의 계측 방법을 개선하기 위한 실험적 연구를 수행하였다. 실험은 하이드로폰을 적용한 수리모형 실험 장치를 구축하고 현장에서 취득한 시료 중 대표시료로 분류된 두 가지 입자에 대해서 수리 조건 변화에 따른 충돌음향을 계측 및 분석하였다. 연구결과 입자크기 및 수리조건 변화에 따른 하이드로폰의 인지특성을 파악할 수 있었고 소류사 충돌음과 연관성 높은 주파수 대역을 분리하여 소류사 충돌음을 판독할 수 있는 계측알고리즘을 제시하였다. 특히 본 연구에서 제안하는 하이드로폰 충돌음향 분석법 B-P Method는 낮은 유속과 작은 입경의 소류사의 조건일 때 타 방법에 비해 제안된 B-P Method가 높은 판독률을 보여주었다.

• Journal of Power System Engineering
• /
• v.5 no.1
• /
• pp.64-72
• /
• 2001

According to the regulation of IMO, oil discharge from ships is allowed under 15ppm only and an oil filtering equipment is essential. However, for large ships using heavy fuel oil of over S.G 0.98 and viscosity 380cSt and system oil, it has been in difficulty to process with existing filtering type of oily water separator. A parallel plate type oily water separator which is one of gravity type separators can be used as an assistant equipment for the oil filtering system to meet the present IMO standard of 15 ppm, because it is an efficient method in dealing with a large amount of rich oil with high specific gravity. This work is focused on the fundamental investigation of the performance of the plate type oily water separator by visualization method and PIV(Particle Image Velocimetry) measurement to acquire multi-point velocity data simultaneously. The experimental results showed that the space of the plates acts a significant role in separating process and it was found that an important point to minimize a vortex flow is to flow a large amount of fluid in space of the plates in order to promote the efficiency of separation.

• Korean Chemical Engineering Research
• /
• v.46 no.6
• /
• pp.1069-1074
• /
• 2008

In this work, we made a study for the 3D SAM formation of octanethiol, decanethiol, and dodecanethiol on copper nanoparticles and we verified stability of the copper particle depending on the ratio of dodecanethiol to copper. The reaction was performed in a one-phase system under nitrogen atmosphere and the thiolated copper particles could be obtained by centrifugation. We could confirm that the nanoparticles consisted of a spherical shape of 3~6 nm from TEM images. FT-IR, XPS and TGA results showed that alkanethiols were chemisorbed via thiol group and the packing density of the alkanethiols on copper surface increased with the alkyl chain lengths. XRD patterns gave us useful information about superlattice formations. Finally, $Cu_2O$ was formed when the molar ratio of dodecanethiol to copper is less than unity and copper nanoparticles formed more compact 3D SAMs when the molar ratio of dodecanethiol to copper was 1.25.

• Applied Chemistry for Engineering
• /
• v.34 no.1
• /
• pp.23-29
• /
• 2023

Microfluidic reactors have been made to achieve significant development for the generation of new functional materials to apply in a variety of fields. Over the last decade, microfluidic reactors have attracted attention as a user-friendly approach that is enabled to control physicochemical parameters such as size, shape, composition, and surface property. Here, we develop a centrifugal microfluidic reactor that can control the flow of fluid based on centrifugal force and generate multifunctional particles of various sizes and compositions. A centrifugal microfluidic reactor is fabricated by combining microneedles, micro- centrifuge tubes, and conical tubes, which are easily obtained in the laboratory. Depending on the experimental control param- eters, including centrifuge rotation speed, alginate concentration, calcium ion concentration, and distance from the needle to the calcium aqueous solution, this strategy not only enables the generation of size-controlled microparticles in a simple and reproducible manner but also achieves scalable production without the use of complicated skills or advanced equipment. Therefore, we believe that this simple strategy could serve as an on-demand platform for a wide range of industrial and academic applications, particularly for the development of advanced smart materials with new functionalities in biomedical engineering.

• Journal of ILASS-Korea
• /
• v.25 no.4
• /
• pp.162-169
• /
• 2020

The worldwide focus on reducing the emissions, fuel and lubricant consumption in T-GDI engines is leading engineers to consider the crankcase ventilation and oil mist separation system as an important means of control. In today's passenger cars, the oil mist separation systems mainly use the inertia effect (e.g. labyrinth, cyclone etc.). Therefore, this study has investigated high efficiency cylinder head-integrated oil-mist separator by using a compact multi-impactor type oil mist separator system to ensure adequate oil mist separation performance. For this purpose, engine dynamometer testing with oil particle efficiency measurement equipment and 3D two-phase flow simulation have been performed for various engine operating conditions. Tests with an actual engine on a dynamometer showed oil aerosol particle size distributions varied depending on operating conditions. For instance, high rpm and load increases bot only blow-by gases but the amount of small size oil droplets. Submicron-sized particles (less than 0.5 ㎛) were also observed. It is also found that the impactor type separator is able to separate nearly no droplets of diameter lower than 3 ㎛. CFD results showed that the complex aerodynamics processes that lead to strong impingement and break-up can strip out large droplets and generate more small size droplets.

• Applied Microscopy
• /
• v.29 no.1
• /
• pp.67-73
• /
• 1999

It is practically hard to prepare good TEM specimens from powders which are embedded in epoxy materials for ion milling, because the milling rate difference between powders and epoxy is quite large. In order to overcome this problem, we tried to find methods to increase the density of powders in the embedding epoxy without loosing the adhesive strength between them. Powder density was considerably increased by employing a centrifuge for embedding, compared to the result by a conventional vacuum embedding. In addition, mixing powders of different sizes after sieving also enhanced the final density by allowing smaller particles filling in the gaps of larger particles. Ion milling of powders embedded by these methods resulted in thin specimens good enough for normal TEM works. TEM specimens from spherical, platy and fibrous powders of submicron size were successfully prepared by this centrifuging method.