• Korean Chemical Engineering Research
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• 제43권2호
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• pp.243-248
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• 2005

분리막 투과증발은 증류에 비하여 낮은 에너지를 요구하기 때문에 물/유기물 혼합물의 분리에 이용될 수 있으며 공비 혼합물이나 이성질체의 분리에 선호되는 방법이다. 제올라이트 분리막은 고분자 분리막에 비하여 열적, 기계적, 화학적 안정성이 우수하며 NaA 제올라이트 분리막은 큰 친수성을 나타내므로 물/유기물 혼합물로부터 효율적인 물 분리에 적합하다. 본 연구에서는 NaA 제올라이트 분리막을 이용한 투과증발 막분리 공정을 이용하여 물/에탄올 혼합물에서 선택적으로 물을 분리하고자 하였다. 에탄올의 공급 농도가 증가함에 따라 총투과플럭스는 감소하였으며 선택도는 증가한 후 높은 에탄올 농도에서 감소하는 것을 관찰할 수 있었다. 실험 온도의 증가에 따라 총투과플럭스는 증가하였으며 선택도 또한 증가하였지만 높은 에탄올 농도에서는 감소하였다. 160시간 이상의 장기간 실험을 통하여 총투과플럭스와 선택도가 안정적으로 일정함을 확인할 수 있었다. 또한, 본 연구를 통하여 얻어진 NaA 제올라이트 분리막은 증류 및 PVA 계열 고분자 분리막보다 우수한 성능을 나타냄을 알 수 있었다.

• 한국초전도ㆍ저온공학회논문지
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• 제20권2호
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• pp.1-5
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• 2018

Arsenic (As) is one of the elements having most harmful impact on the human health. Arsenic is a known carcinogen and arsenic contamination of drinking water is affecting on humans in many regions of the world. Adsorption has been proved most preferable technique for the removal of arsenic. Many researchers have studied various types of solid materials as arsenic adsorbent, and iron oxide and its modified forms are considered as the most effective adsorbent in terms of adsorption capacity, recovery, and economics. However, most of all iron oxides have small surface area in comparing with common adsorbents in environmental application such as activated carbon but the activated carbon has weak sorption affinity for arsenic. We have used an activated carbon as base adsorbent and iron oxide coating on the activated carbon as high affinity sorption sites and giving magnetic attraction ability. In this study, adsorption properties of arsenic and magnetic separation efficiency of the magnetized activated carbon (MAC) were evaluated with variable iron oxide content. As the iron oxide content of the MAC increased, adsorption capacity has also gradually increased up to a point where clogging by iron oxide in the pore of activated carbon compensate the increased sorption capacity. The increase of iron oxide content of the MAC also affected magnetic properties, which resulted in greater magnetic separation efficiency. Current results show that magnetically modified common adsorbent can be an efficiency improved adsorbent and a feasible environmental process if it is combined with the magnetic separation.

• 한국재료학회지
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• 제19권2호
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• pp.79-84
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• 2009

A series of experiments demonstrated that an addition of Ag into $(Cu_{0.5}Zr_{0.5})_{100-x}Ag_{x}$ amorphous alloys alters the plasticity of the alloys in a systematic manner. Energy dispersive x-ray spectroscopy (EDS) conducted on the $(Cu_{0.5}Zr_{0.5})_{100-x}Ag_{x}$ alloys exhibited the presence of compositional modulation, indicating that compositional separation had occurred. The presence of compositional modulation was also validated using a combined technique of molecular dynamics and Monte Carlo simulation. In this study, the effect of Ag on the compositional separation in $(Cu_{0.5}Zr_{0.5})_{100-x}Ag_{x}$ bulk amorphous alloys was investigated to understand the role played by the phase-separating element on the plasticity of the amorphous alloys.

• 설비공학논문집
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• 제22권4호
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• pp.213-218
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• 2010

In this study, a star screen model was constructed to predict the dynamic characteristics of interactive waste particles and to simulate separation capability of the particle using geared type screen(star screen). In order to approach this model, it is necessary to determine the design parameters of the screen such as driving torque, percentage of open space, and capability. Thus, a dynamic star screen model was developed with a total of 32 columns of geared assembly including screen part, wastes guide, and extra joints to rotate the screen using ADAMS. Each parameter was simulated to predict the screening capability for particle size, rotating speed, and particle condition. From the results, separation ability was predicted according to the affecting variables by using the dynamic star screen model.

• ETRI Journal
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• 제34권2호
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• pp.226-234
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• 2012

The novelty of this study resides in the fabrication of stoichiometric and stress-reduced $Si_3N_4/SiO_2/Si_3N_4$ triple-layer membrane sieves. The membrane sieves were designed to be very flat and thin, mechanically stress-reduced, and stable in their electrical and chemical properties. All insulating materials are deposited stoichiometrically by a low-pressure chemical vapor deposition system. The membranes with a thickness of 0.4 ${\mu}m$ have pores with a diameter of about 1 ${\mu}m$. The device is fabricated on a 6" silicon wafer with the semiconductor processes. We utilized the membrane sieves for plasma separations from human whole blood. To enhance the separation ability of blood plasma, an agarose gel matrix was attached to the membrane sieves. We could separate about 1 ${\mu}L$ of blood plasma from 5 ${\mu}L$ of human whole blood. Our device can be used in the cell-based biosensors or analysis systems in analytical chemistry.

• Journal of Photoscience
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• 제6권3호
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• pp.91-96
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• 1999

Zeolites and microporouos materials continue to attract attention as novel hosts for photochemical reactions. Zeolities are attractive because of their ability to selectivity exchange and incorporate species within the void spaces and interconnecting channels, providing a spatial arrangement of molecules. Our research has primarily focused on intrazeolitic electron transfer from excited Ru(bpy)32+ in supercages of zeolite Y to a series of bipyridinium ions. In the Ru(bpy)32+ viologen-zeolite Y samples, the slowing of the back electron transfer from the bipyridinium radical cation to Ru(bpy)32+ allows for charge propagation via self exchange between diquat molecules. This provides an opportunity for permanent charge separation. When the migrating charge on the diquat radical within the zeolite reaches the surface, it can be transferred to a neutral viologen (PVS) in solution, resulting in permanent charge separation. The advantage of long-lived charge separation can be exploited for useful chemistry if suitable catablysts can be assembled on the zeolities. We have studied Ru(bpy)2 as water oxdiation catalysts. We have demonstrated that synthesis of RuO2 fibers on a zeolite via thermal decomposition of Ru3(CO)12 leads to the most active water decomposition catalyst reported to date. Because of the extensive interest of photochemical water reduction to H2, much is known about catalytic systems usin gone electron catalyst, and even more importantly, that no reaction of viologen occurred with H2 over this catalyst. The present challenge is to incorporate all these elements of the system into an architecture and we are examining zeolite membranes for this purpose.

• Current Optics and Photonics
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• 제8권1호
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• pp.30-37
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• 2024

Implemented at the Geochang Observatory in South Korea, our slope detection and ranging (SLO-DAR) system features a 508 mm Cassegrain telescope (f /7.8), incorporating two Shack-Hartmann wave-front sensors (WFS) for precise measurements of atmospheric phase distortions, particularly from nearby binary or double stars, utilizing an 8 × 8 grid of sampling points. With an ability to reconstruct eight-layer vertical atmospheric profiles, the system quantifies the refractive index structure function (C_n²) through the crossed-beam method. Adaptable in vertical profiling altitude, ranging from a few hundred meters to several kilometers, contingent on the separation angle of binary stars, the system operates in both wide (2.5 to 12.5 arcminute separation angle) and narrow modes (11 to 15 arcsecond separation angle), covering altitudes from 122.3 to 611.5 meters and 6.1 to 8.3 kilometers, respectively. Initial measurements at the Geochang Observatory indicated C_n² values up to 181.7 meters with a Fried parameter (r₀) of 8.4 centimeters in wide mode and up to 7.8 kilometers with an r₀ of 8.0 centimeters in narrow mode, suggesting similar seeing conditions to the Bohyun Observatory and aligning with a comparable 2014-2015 seeing profiling campaign in South Korea.

• 한국정밀공학회지
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• 제23권3호
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• pp.171-178
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• 2006

The sonication mettled is widely used with surfactants to suspend individual single-walled carbon nanotubes in solution, and it is well known that sonication-induced tube cutting occurs. Recently, it is found out that ultrasonicated nanotubes yield simultaneous separation by tube length and diameter. Nanotubes that have been cut shortest possess the greatest enrichments of large-diameter species. In this study, single-walled carbon nanotubes are cut using a ball milling method. Similar fracture behavior is observed fur the ball milled nanotubes: i.e., large diameter tubes are cut shorter. The ability to separate carbon nanotubes by diameter and length will contribute to tile development of nanotube-based applications.

• Environmental Engineering Research
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• 제16권1호
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• pp.35-39
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• 2011

An integrated gasification combined cycle (IGCC) system has been attracting attention due to its increased energy conversion efficiency and ability to treat various carbonaceous materials. IGCC is also expected to play an important role in the future supply of hydrogen energy. The use of a palladium-based membrane to separate the hydrogen from the synthesis gas stream has been intensively studied due to its exceptional hydrogen-separating capability. However, theoretical research on hydrogen separation is still an unfamiliar area in Korea. First-principle density functional theory was applied in this study to investigate the dissociative adsorption of hydrogen onto a palladium surface. The stability of hydrogen on the surface was theoretically evaluated with various adsorption configurations, partial pressures and temperatures. Further theoretical and experimental studies were also suggested to find a more hydrogen-selective material.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.71-75
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• 2001

The first step for recycling the CRT bulb is to remove frist seals between the panel and funnel. For this purpose, various kinds of methods have been used. One of those is to use the nitric acid, which is a proven technology and widely used in CRT-making industries. The process. however. has a problem of NOx generation. Such a drawback can be overcome by using a new chemical. This new chemical can remove the frit without NOx generation. This paper describes the dissolution ability of the chemical for lead and zinc oxides and the application to the separation of the CRT panel from its funnel.