• Transactions of the Korean hydrogen and new energy society
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• v.15 no.3
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• pp.220-227
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• 2004

The purpose of this paper is, based on the theoretical background of the principle of gas purification and absorption, and the absorbing ability of metals, to syudy the efficiency of gas purification of inorganic gases using Zr alloys, so as to contribute to the IT industry. To produce and distribute gas with high purity and ultra-high purity, different types of gas purifier are currently being used: distillation type, getter type, catalyst type, absorption at low-temperature type, and membrane separation equipment. From the different purification methods mentioned above, the getter type gas purifier is capable of not only high performance and capacity but also P.O.U(Point Of Use) method. The key of the getter type gas purifier is its efficiency of gas purification, which is the subject chosen for this study.

• Journal of the Korean Ceramic Society
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• v.46 no.5
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• pp.462-466
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• 2009

We investigated the pore properties of inorganic membranes applied for hydrogen separation industry. Inorganic membranes were derived from polysilazanes. The thermal reactions involved were studied using thermogravimetry(TG) and IR spectroscopy(FTIR) of the solids. To determine the thermal effect of pore properties, polysilazanes were pyrolysed in inert atmosphere. Pore volume and BET surface area showed the maximum value at a pyrolysis temperature of $500^{\circ}C$. For amorphous SiCN membrane derived from polysilazanes, selectivity of $H_2/N_2$ was 4.81 at $600^{\circ}C$.

• Membrane Journal
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• v.12 no.2
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• pp.107-119
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• 2002

Carbon-silica ($C-SiO_2$) membranes can be easily prepared by the pyrolysis of two-phase copolymers containing an aromatic imide block and a siloxane block and remarkably high permselectivities of $He/N_2, O_2/N_2,$ and $CO_2/N_2$. The pyrolysis of the imide-siloxane block copolymers was carried out at different final temperatures, $600^{\circ}C, 800^{\circ}C,$ and $1000^{\circ}C$ under an inert atmosphere, and is the first reported case of the precursors being used for the preparation of carbon membrane. The polymeric precursors were synthesized in a wide range of siloxane content and different final morphology, and the pyrolozed membranes were tested with a high vacuum time-lag method at $25^{\circ}C$ and 76cmHg of feed pressure. In experiments with He, $CO_2, O_2 \;and \;N_2$, the membranes were found to have good $O_2/N_2$ selectivity up to 32.2 and $O_2$ permeability on the order of $10-8/cm^2(STP)cm/cm^2seccmHg.$.

• Membrane Journal
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• v.24 no.4
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• pp.325-331
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• 2014

We synthesized novel polyimides with high gas permeability and selectivity for application of on board inert gas generation system (OBIGGS). 2,2-bis(3,4-carboxylphenyl) hexafluoropropane dianhydride (6FDA) and two kinds of amines with high permeability and solubility were used to prepare the novel polymide. 2,3,5,6-Tetramethyl-1,4-phenylenediamine (TMPD) was used to improve gas permeability and various kinds of diamines were used to improve the gas selectivity respectively. The polyimide copolymers were synthesized by commercial chemical imidization method and their average molecular weights were over 100,000g/mol. The glass temperature ($T_g$) and the thermal degradation temperature were characterized using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The synthesized copolymers showed high $T_g$ over $300^{\circ}C$ and high thermal degradation temperature over $500^{\circ}C$. The gas permeation properties were measured by time-lag equipment. Although general polyimides showed very low gas permeability, synthesized polyimide copolymer showed high $O_2$ permeability of 36.21 barrer with high $O_2/N_2$ selectivity around 4.1. From this result, we confirm that these membranes have possibility to apply to OBIGGS.

• Proceedings of the Membrane Society of Korea Conference
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• 1998.10a
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• pp.96-98
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• 1998

1. 서론 : 팔라듐이나 이의 합금막들은 높은 선택적 투과특성으로 인해 수소 정제나 분리막 반응기와 같은 산업응용 분야에서 매우 높은 관심을 갖고 있다. 상업적으로 이용되고 있는 이러한 막들은 통상적인 metallugical process에 의해 제조괸 self-supported type으로 수소 투과 속도가 낮을 뿐만 아니라 팔라듐 등은 고가의 귀금속이므로 비경제적이다. 따라서 현재 대부분의 연구자들은 기계적 강도를 유지하기 의한 다공성 지지체 위에 얇은 금속 박막을 코팅함으로서 투과성을 높이는 동시에 경제적인 복합막 형태의 막을 만드는데 연구의 촛점을 맞추고 있다. 이러한 형태의 막을 제조하기 위한 금속 박막 제조법은 무전해 도금법(electroless deposition), 화학증착법(CVD), 스퍼터링(sputtering), 전해도금법(electrodeposition) 등이 시도되었다. 그러나 수소에 대한 우수한 선택적 투과 특성을 갖기 의해서는 대부분 5$\mu$m 이상의 두꺼운 막을 제조하였으며 이보다 얇은 막의 제조에 한계가 있기 때문에 이들 막에 대한 기체 투과 특성에 대한 연구결과는 많지 않다. 본 연구에서는 기존의 전기도금법을 응용한 소위 'vacuum electrodeposition' 이란 새로운 기술을 도입함으로써 우수한 선택적 투과성을 갖는 2$\mu$m 이하의 팔라듐 합금 박막 제조를 가능하게 하였다. 지지체 표면의 거칠음 정도, 평균 기공 크기 등의 지지체 성질의 조절에 의한 금속 박막의 핀홀을 최소화함으로써 질소와 같은 inert gas의 투과도는 거의 없게 유지하는 동시에 금속 박막 두께, 결정 구조(e.g. grain size), 합금 조성 등을 조절함으로써 수소의 투과도를 높이고자 하였다. 있다. 후자의 경우, 미량의 과산화수소수 (1~10,000 ppm)를 이용해 처리 해주는 방법의 경우 경제적으로 큰 장점이 있고, 처리가 단순하다는 장점이 있으나 과산화수소수 자체에 포함하고 있는 높은 impurit level, 그리고 처리후 장시간의 flushing time을 가져야 한다는 단점등이 존재 하고 있다.요구된다. 몰입이 가능하여 임계치가 저하된 것으로 여겨진다. 또한 광학적 이득의 존재는 이 구조에 의한 극단파장 반도체 레이저다이오드의 실현 가능성을 나타내는 것이다.548 mL에 비해 통계학적으로 의의 있게 적었다(p<0.05). 결론: 관상동맥우회로 조성수술에서 전방온혈심정지액을 사용할 때 희석되지 많은 고농도 포타슘은 fliud overload와 수혈을 피하고 delivery kit를 사용하지 않음으로써 효과적이고 만족할 만한 심근보호 효과를 보였다.를 보였다.4주까지에서는 비교적 폐포는 정상적 구조를 유지하면서 부분적으로 소폐동맥 중막의 비후와 간질에 호산구 침윤의 소견이 특징적으로 관찰되었다. 결론: 분리 폐 관류는 정맥주입 방법에 비해 고농도의 cisplatin 투여로 인한 다른 장기에서의 농도 증가 없이 폐 조직에 약 50배 정도의 고농도 cisplatin을 투여할 수 있었으며, 또한 분리 폐 관류 시 cisplatin에 의한 직접적 폐 독성은 발견되지 않았다이 낮았으나 통계학적 의의는 없었다[10.0%(4/40) : 8.2%(20/244), p>0.05]. 결론: 비디오흉강경술에서 재발을 낮추기 위해 수술시 폐야 전체를 관찰하여 존재하는 폐기포를 놓치지 않는 것이 중요하며, 폐기포를 확인하지 못한 경우와 이차성 자연기흉에 대해서는 흉막유착술에 더 세심한 주의가 필요하다는 것을 확인하였다. 비디오흉강경수술

• BMB Reports
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• v.44 no.2
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• pp.87-95
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• 2011

Enzymatic catalysis has been pursued extensively in a wide range of important chemical processes for their unparalleled selectivity and mild reaction conditions. However, enzymes are usually costly and easy to inactivate in their free forms. Immobilization is the key to optimizing the in-service performance of an enzyme in industrial processes, particularly in the field of non-aqueous phase catalysis. Since the immobilization process for enzymes will inevitably result in some loss of activity, improving the activity retention of the immobilized enzyme is critical. To some extent, the performance of an immobilized enzyme is mainly governed by the supports used for immobilization, thus it is important to fully understand the properties of supporting materials and immobilization processes. In recent years, there has been growing concern in using polymeric materials as supports for their good mechanical and easily adjustable properties. Furthermore, a great many work has been done in order to improve the activity retention and stabilities of immobilized enzymes. Some introduce a spacer arm onto the support surface to improve the enzyme mobility. The support surface is also modified towards biocompatibility to reduce non-biospecific interactions between the enzyme and support. Besides, natural materials can be used directly as supporting materials owning to their inert and biocompatible properties. This review is focused on recent advances in using polymeric materials as hosts for lipase immobilization by two different methods, surface attachment and encapsulation. Polymeric materials of different forms, such as particles, membranes and nanofibers, are discussed in detail. The prospective applications of immobilized enzymes, especially the enzyme-immobilized membrane bioreactors (EMBR) are also discussed.

• Food Science of Animal Resources
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• v.26 no.3
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• pp.402-409
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• 2006

Although microorganisms are, in fact, the most diverse and abundant type of organism on Earth, the ecological functions of microbial populations remains poorly understood. A variety of bacteria including marine Vibrios encounter numerous ecological challenges, such as UV light, predation, competition, and seasonal variations in seawater including pH, salinity, nutrient levels, temperature and so forth. In order to survive and proliferate under variable conditions, they have to develop elaborate means of communication to meet the challenges to which they are exposed. In bacteria, a range of biological functions have recently been found to be regulated by a population density-dependent cell-cell signaling mechanism known as quorum-sensing (QS). In other words, bacterial cells sense population density by monitoring the presence of self-produced extracellular autoinducers (AI). N-acylhomoserine lactone (AHL)-dependent quorum-sensing was first discovered in two luminescent marine bacteria, Vibrio fischeri and Vibrio harveyi. The LuxI/R system of V. fischeriis the paradigm of Gram-negative quorum-sensing systems. At high population density, the accumulated signalstrigger the expression of target genes and thereby initiate a new set of biological activities. Several QS systems have been identified so far. Among them, an AHL-dependent QS system has been found to control biofilm formation in several bacterial species, including Pseudomonas aeruginosa, Aeromonas hydrophila, Burkholderia cepacia, and Serratia liquefaciens. Bacterial biofilm is a structured community of bacterial cells enclosed in a self-produced polymeric matrix that adheres to an inert or living surface. Extracellular signal molecules have been implicated in biofilm formation. Agrobacterium tumefaciens strain NT1(traR, tra::lacZ749) and Chromobacterium violaceum strain CV026 are used as biosensors to detect AHL signals. Quorum sensing in lactic acid bacteria involves peptides that are directly sensed by membrane-located histidine kinases, after which the signal is transmitted to an intracellular regulator. In the nisin autoregulation process in Lactococcus lactis, the NisK protein acts as the sensor for nisin, and NisR protein as the response regulator activatingthe transcription of target genes. For control over growth and survival in bacterial communities, various strategies need to be developed by which receptors of the signal molecules are interfered with or the synthesis and release of the molecules is controlled. However, much is still unknown about the metabolic processes involved in such signal transduction and whether or not various foods and food ingredients may affect communication between spoilage or pathogenic bacteria. In five to ten years, we will be able to discover new signal molecules, some of which may have applications in food preservation to inhibit the growth of pathogens on foods.