The gas sensor is essential to monitoring dangerous gases in our environment. Metal oxide (MO) gas sensors are primarily utilized for flammable, toxic and organic gases and O3 because of their high sensitivity, high response and high stability. Tungsten oxides (WO3) have versatile applications, particularly for gas sensor applications because of the wide bandgap and stability of WO3. Nanosize WO3 are synthesized using the hydrothermal method. Asprepared WO3 nanopowders are in the form of nanorods and nanorulers. The crystal structure is hexagonal tungsten bronze (MxWO3, x =< 0.33), characterized as a tunnel structure that accommodates alkali ions and the phase stabilizer. A gas detection test reveals that WO3 can detect acetone, butanol, ethanol, and gasoline. This is the first study to report this capability of WO3.

본 연구는 초고성능 콘크리트의 성능을 보다 향상시키기 위해 현재 콘크리트 보강에 사용하는 섬유들을 조합한 복합 섬유를 제작하여 복합섬유 혼입 초고성능 콘크리트의 강도 특성을 분석하였다. 복합섬유 4종과 단일섬유 3종을 각각 혼입하여 유동성과 압축, 휨강도 실험을 진행하였다. 복합섬유와 단일섬유 혼입 시험체 모두 유동성 평가를 만족하였으며, 단일섬유가 조금 더 우수한 성능을 나타내었다. 강도 평가결과 파라아라미드 섬유와 강섬유를 조합한 복합섬유 2종이 가장 우수한 결과를 나타내었으며, 복합섬유 직경 차이에 따라 압축 및 휨강도 보강효과가 다르게 나타난 것을 확인할 수 있었다. 압축강도 감소를 최소화하며 휨강도를 증가시킨 결과를 통해, 복합섬유는 단일섬유 간의 단점을 서로 보완할 수 있을 것으로 판단되며, 본 연구를 통해 차후 콘크리트의 다양한 재료적 특성을 보강하는 복합섬유도 충분히 제작 가능할 것으로 판단된다.

고체 알칼리 연료전지에서는 작동 시 물이 생성되어 water flooding 현상이 나타나는 산화극과 반대로 물이 소진되어 water drying 현상이 나타나는 환원 극과의 water balance 가 매우 중요하다. 이번 연구에서는 기존의 상용막(Fuma tech)을 사용하여 막의 양면에 solvent assisted lithography를 통해 서로 엇갈린 라인 패턴을 형성하였다. 양면 패터닝을 통해 오믹저항의 감소와 함께 water back-diffusion을 향상시켰으며, 넓어진 계면에 의해 산화극의 mass transport를 향상시킬 수 있었다. 또한, 환원극에서는 넓어진 계면에 의해 촉매의 활용률이 증가하였고 이러한 복합적인 효과를 통해, 1.0 Wcm-2 라는 고성능을 얻을 수 있었다.

Recently, many efforts to enhance separation performance of the reverse osmosis (RO) membranes have been made. Among them, the post treatment with organic solvent, so called solvent activation, has been recognized as an effective method to improve membrane performance. However, solvent activation enhances water flux along with the loss of NaCl rejection. Furthermore, there have been no clear mechanisms and reliable criteria of the solvent activation effects. In this study, we demonstrate that a new type of organic solvent, benzyl alcohol, can effectively activate the RO membrane to significantly enhance water permeation without deteriorating NaCl. Based on this results, we elucidate the underlying solvent activation mechanism and propose a reliable indicator of the solvent activation effect.

High performance polydimethylsiloxane (PDMS) membranes for n-butanol recovery were fabricated using a tri-functional crosslinker containing the phenyl group. In order to understand the role of the functional group structure and cross-linking density in pervaporation performance, PDMS membranes were prepared using tri-functional crosslinker containing other functional groups (hexyl and cyclohexyl) and conventional tetra-functional crosslinker. The relationship between the polymer structure-performance was discussed based on the sorption and diffusion properties of the membranes. As a result, the phenyl-based PDMS membrane exhibited the pervaporation performance owing to the strong hydrophobicity and chain rigidity of the phenyl group compared to other PDMS membranes even at high butanol concentration and high temperature conditions.

A highly performing and durable forward osmosis (FO) membrane was prepared using a polydopamine-modified polyolefin (DPO) support via an aromatic solvent (toluene)-based interfacial polymerization (IP). The hydrophobic polyolefin support was uniformly hydrophilized by polydopamine coating, which provided long term operation stability. In addition, a highly permselective selective layer was prepared on the hydrophilic DPO support by the toluene-based IP, which promoted amine diffusion and the subsequent IP reaction. As a result, the prepared DPO-supported TFC membrane exhibited significantly high FO performance, which was ~4.9 times higher FO water flux and ~62% lower specific salt flux than those of a commercial FO (HTI-CTA) membrane in FO mode. Furthermore, its excellent mechanical and chemical stability enabled stable operation.

유기용매 나노여과(OSN, organic solvent nanofiltration) 분리막은 폴리이마이드(PI)나 폴리벤질이미디아졸(PBI)과 같은 특수 고분자의 개발, 상업화가 이루어지고 강한 유기용매에 견딜 수 있도록 가교를 통해 분리막의 내구성이 급격하게 향상되면서 저분자량의 합성, 정제 및 농축을 필요로하는 의약, 바이오, 식품산업에 획기적이고 효율적인 분리막 공정으로 주목 받고 있다. 하지만 여전히 고가의 고분자, 가교를 위한 복잡한 프로세스, 다량의 강한 용매 폐수 발생등 상업화를 이루는데 여러 가지 문제점들이 산재하고 있다. 본 연구는 기존 제막 방식에서 벗어나 무독성의 용제를 사용하여 단일공정으로 유기용매 나노여과 분리막을 제막하고 그 특성을 연구하였다.

신재생 에너지의 확대를 위한 대용량 에너지 저장장치로서 레독스 흐름전지 기술의 중요성이 부각되고 있다. 레독스 흐름전지는 양극 및 음극 전해액을 셀에 순환시켜 전해액에 용해되어 있는 활물질의 산화 및 환원 반응을 유도시키는 전지로서 전지의 효율 및 수명 확보를 위해서 양쪽 전해액을 분리시켜 주며 이온전달을 일으킬 수 있는 멤브레인의 사용이 필수적이다. 그러나 기존 레독스 흐름전지에 사용되는 멤브레인은 활물질 차단 특성, 이온 전달 특성, 물리화학적 내구성 및 가격 측면에서 부족한 특성이 많으며, 이를 개선함으로서 레독스 흐름전지의 효율, 수명 향상 및 가격저감 효과를 얻을 수 있다. 본 연구에서는 이러한 레독스 흐름전지용 멤브레인의 문제점을 정리하고, 이를 개선시키기 위한 멤브레인 소재 및 구조설계 전략에 대해 논의한다. 특히 활물질 차단과 내구성 향상 혹은 가격저감을 동시에 만족시키는 복합막 기술을 소개한다.

We fabricated dual-phase free-standing polymeric membrane for high performance CO2/N2 separation, introducing amphiphilic, CO2-philic copolymer via one-step free radical polymerization, or (2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]ethyl methacrylate)-graft-poly(oxyethylene methacrylate) (PBE). PBE filler partially interacts with Pebax polymer matrix to generate the interconnected CO2 philic network, exhibiting a microphase-separated, or dual-phase behavior in Pebax matrix. The performance of CO2/N2 separation was increased according to the PBE content, with the maximum selectivity at 5 wt%. The enhancement of Pebax/PBE CO2-philic membrane was attributed to the formation of CO2-philic channel consisting of ether oxygens and triazole groups. The best performance was CO2 permeability of 175.3 Barrer and CO2/N2 selectivity of 48.2.

We report on the fabrication of a high performance reverse osmosis membrane based on a hydrophilic polyacrylonitrile support via an aromatic solvent-assisted interfacial polymerization process. The use of aromatic solvent (toluene or xylene) produced the membranes with unprecedentedly high NaCl rejection (~99.9%) and superior water flux, outperforming both the control membrane prepared using a conventional aliphatic solvent (n-hexane) and commercial membranes. The membranes fabricated using toluene or xylene had roof-like structures covering a thin and highly dense polyamide (PA) layer, which was induced by enhanced amine diffusion and the extended miscible layer resulting from the increased miscibility of aromatic solvent with water. The high performance of the membranes is attributed to thin and highly cross-linked basal PA layer.

수소를 연료로 사용하는 PEMFC는 고효율⋅출력밀도를 나타내며, 짧은 시동시간, 우수한 응답특성에 따라 현지설치형 발전기술로 사용되며, 이를 위한 고효율 연료처리장치가 필수적이다. SMR반응은 연료당 고회수율을 때문에 경제성이 우수하며, 전환율 확보를 위해 700°C, 20 bar 이상의 운전조건에서 수행되며, WGS, PSA의 후단공정을 통해 수소를 생산한다. 분리막 개질기를 이용한 SMR반응은 분리막이 수소를 제거함에 따라 반응효율 증진, 공정온도 저감, 후단공정 배제를 할 수 있어 공정구성 및 경제성이 우수하다. 본 연구에서는 팔라듐분리막 개질기를 사용하여 550°C, 5 bar에서 SMR반응을 통해 수소를 생산하였으며, 개질된 가스의 CO 농도를 최소화하여 고온 PEMFC용 연료처리장치를 개발하였다.

MOF는 높은 표면적, 균일한 공극, 크기를 가지는 새로운 클래스의 porous material 이다. MOF는 금속과 organic linker가 coordination 결합에 의해 연결되어 있고, 온도에 대한 강한 안정성을 나타내고, 높은 표면적 때문에 촉매, 분리, 개스저장 등 다양한 분야에 적용될 수 있는 잠재력이 풍부하다. MOF는 zeolite보다 높은 표면적을 가지고 작용기를 organic linker에 따라 쉽게 바꿀 수 있는 장점 때문에 최근에 많은 관심을 받게 되었다. 다양한 MOF가 합성되었고 CO2/N2 선택도, 흡착량, 수분과 산성가스에 대한 안정성이 분석되었다. 최종적으로 선택된 MOF는 폴리머와 결합하여 하이브리드 멤브레인을 만드는 데에 사용되었다.

PURPOSES : This purpose of this study is to analyze the effect to autogenous shrinkage of the top-layer material of a two-lift concrete pavement mixing both silica fume and polymer powder. METHODS: The bottom-layer of a two-lift concrete pavement was paved with original portland cement (OPC) with a 20~23 cm thickness. Additionally, the top-layer which is directly exposed to the environment and vehicles was paved with a high-performance concrete (HPC) with a 7~10 cm thickness. These types of pavements can achieve a long service life by reducing joint damage and increasing the abrasion and scaling resistance. In order to integrate the different bottom and top layer materials, autogenous shrinkage tests were performed in this study according to the mixing ratio of silica fume and polymer powder, which are the admixture of the top-layer material. RESULTS: Autogenous shrinkage decreased when polymer powder was used in the mix. Contrary to this, autogenous shrinkage tended to rise with increasing silica fume content. However, the effects were not significant when small amounts of polymer powder were used (3% and 11%). CONCLUSIONS : The durability and compressive strength increase when silica fume is used in the mix. The flexural strength considerably increases and autogenous shrinkage of concrete decreases when polymer powder is used in the mix. As seen from above, the proper use of these materials improves not only durability, but also autogenous shrinkage, leading to better shrinkage crack control in the concrete.

It is a well known that concrete is strong for compression and weak for tension. For reinforcing the weakness and improving the performance about concrete, various methods are used. Fiber reinforced concrete that is one of them has been investigated in this study. The function of fiber in concrete is to improve the stress strain relation and toughness, crack control. It’s applied from normal strength concrete to ultra-high performance concrete. But it is essential to disperse fiber uniformly and to prevent aggregation of fiber in concrete, in order that fiber reinforced concrete show the sufficient performance. The various properties of fiber affect the essential properties, for instance, length and diameter of fiber, source, etc. So, this study evaluated the ultra-high performance concrete with mixed in composite fiber.

5-fluorouracil (5-FU) is a pyrimidine analog which can work as antineoplastic antimetabolite by blocking thymidylate synthetase conversion of deoxyuridylic acid to thymidylic acid in DNA synthesis. This study is aimed to know the anticancer effect of 5-FU on the expressions of important signaling proteins in KB cells through immunoprecipitation high performance liquid chromatography (IP-HPLC). KB cells were treated with 5 μM 5-FU and cultured for 12, 24, 48, 72, and 96 hours, and followed by IP-HPLC analysis using 32 antisera. 5-FU suppressed the proliferation of KB cells by decreases in the expressions of proliferation-related proteins, Ki-67, PCNA, CDK4, and MPM2 to 82.6%, 92.4%, 95.2%, and 95.9%, respectively, but increases of antiproliferation-related proteins, p16 and p21 to 106.7% and 125.5%, respectively, during 96 hours of experiment. This proliferation reduction was also negatively regulated by cMyc/MAX/MAD network signaling. The cellular protection and survival were consistently arrested by 5-FU treatment in KB cells. The expressions of NFkB, MDR, p-mTOR, and TNFα were decreased to 95.1%, 92.8%, 93.4%, and 90.3% in 48-72 hours, respectively, while cellular stress was increased by upregulation of p38 to 111.3% in 48 hours. And the expressions of pAKT1/2/3, hTERT, and AMPK were also decreased to 93.3%, 97.4%, and 89.3% in 24-48 hours, respectively, while the cellular transformation might be undergone by upregulation of TGF-β1 to 117% until 96 hours. Particularly, 5-FU treatment greatly induced the cellular apoptosis in KB cells by increased expressions of PARP, cPARP, caspase 9, c-caspase 9, caspase 8, and caspase 3 in the lack of p53/BAX and FASL/FAS signaling. The expressions of PARP and c-PARP were increased maximum to 119.2% in 24 hours, and followed by increases of caspase 9, c-caspase 9, caspase 8, and caspase 3 to 111.2%, 125.9%, 108.6%, and 116.3% in 72-96 hours. Therefore, it is presumed that 5-FU induced cellular apoptosis in KB cells may be derived from the overexpression of PARP due to the increased DNA defect caused by 5-FU, which can lead to ATP depletion and subsequent cellular apoptosis.

The highly performing polyamide (PA) thin film composite (TFC) reverse osmosis (RO) membrane was prepared using the commercialized porous polyolefin (PO) membrane as a support. The PO-supported TFC (PO-TFC) membrane was fabricated via a conventional interfacial polymerization process. The highly permselective PA layer was formed by optimizing membrane fabrication parameters such as monomer/additive composition and post-treatment. The uniform pore structure and high surface porosity of the PO support are beneficial for improving the membrane permselectivity. As a result, the prepared PO-TFC membrane showed ~30% higher water flux and ~0.4% higher NaCl rejection compared to a commercial RO membrane. In addition, the PO-TFC membrane exhibited excellent mechanical properties and organic solvent resistance.

터널 내 주행시 도로이용자에게 주행 쾌적성 및 안전성 향상을 위하여 터널 콘크리트 포장 표면에 고성능 표면처리 공법(NGCS : Next Generation Concrete Surface), 다이아몬드 그라인딩 공법(DG : Diamond Grinding) 등을 적용하고 있다. 최근 개통된 노선 중에서 표면처리 공법을 적용한 터널 포장에 대하여 미끄럼저항(ASTM E 274) 및 타이어-노면 마찰소음(ISO 11819)을 측정하였다. NGCS가 적용된 터널구간은 평택제천선 금성터널(공용 약 25개월), 울산포항선 양북1터널(공용 약 12개월), 서울양양선 인제터널(공용 약 1개월)이며, DG가 적용된 구간은 평택제천선 산척4터널(공용 약 25개월)이다. 미끄럼저항 측정결과를 그림 1에 나타내었다. NGCS 적용구간의 미끄럼 저항이 DG구간보다 다소 낮았으나 모두 유지관리기준을 만족하였다. 타이어-노면 마찰소음 측정결과를 그림2에 나타내었다. NGCS 적용구간이 DG 적용구간보다 소음이 더 작게 발생하는 것으로 분석되었다.

고성능 복합재료는 기존의 소재에 비해 우수한 기계적 물성을 보이며 특히 높은 비강도를 보인다. 복합재료 의 매트릭스로 사용되는 에폭시 수지는 이들의 독특한 화학반응성, 경화반응에 사용되는 경화제의 적절한 조합으로 많은 다양한 특성을 보일 수 있다. 본고에서는 고성능 복합재 구조물 제작에 사용되어온 에폭시 수지 시스템을 소개 하고자 한다. 필라멘트 와인딩 공법에 사용되는 에폭시 수지와 프리프레그 제조에 사용되는 에폭시 수지의 조성과 특 성을 중심으로 설명하였다.

Pressure retarded osmosis(PRO) has attracted much attention as potential technology to reduce the overall energy consumption for reverse osmosis(RO) desalination. The RO/PRO hybrid process is considered as the most logical next step for future desalination. The PRO process aims to harness the osmotic energy difference of two aqueous solutions separated by a semipermeable membrane. By using the concentrated water(RO brine) discharged from existing RO plants, the PRO process can effectively exploit a greater salinity gradient to reduce the energy cost of processing concentrated water. However, in order to use RO brine as the draw solution, PRO membrane must have high water flux and enough mechanical strength to withstand the high operational pressure. This study investigates the development of a thin film composite PRO membrane and spiral wound module for high power density. Also, the influence of membrane backing layer on the overall power density was studied using the characteristic factors of PRO membranes. Finally, the performance test of an 8-inch spiral wound module was carried out under various operating conditions(i.e. hydraulic pressure, flow rate, temperature). As the flow rate and temperature increased under the same hydraulic pressure, the PRO performance increased due to the growth of water permeability coefficient and osmotic pressure. For a high performance PRO system, in order to optimize the operating conditions, it is highly recommended that the flow pressure be minimized while the flow rate is maintained at a high level.