• Journal of Microbiology and Biotechnology
• /
• v.26 no.12
• /
• pp.2171-2178
• /
• 2016

Polyester cloth (PC) was selected as a prospective inexpensive substitute separator material for microbial fuel cells (MFCs). PC was compared with a traditional Nafion proton exchange membrane (PEM) as an MFC separator by analyzing its physical and electrochemical properties. A single layer of PC showed higher mass transfer (e.g., for $O_2/H^+/ions$) than the Nafion PEM; in the case of oxygen mass transfer coefficient ($k_o$), a rate of $50.0{\times}10^{-5} cm{\cdot}s^{-1}$ was observed compared with a rate of $20.8{\times}10^{-5}cm/s$ in the Nafion PEM. Increased numbers of PC layers were found to reduce the oxygen mass transfer coefficient. In addition, the diffusion coefficient of oxygen ($D_O$) for PC ($2.0-3.3{\times}10^{-6}cm^2/s$) was lower than that of the Nafion PEM ($3.8{\times}10^{-6}cm^2/s$). The PC was found to have a low ohmic resistance ($0.29-0.38{\Omega}$) in the MFC, which was similar to that of Nafion PEM ($0.31{\Omega}$); this resulted in comparable maximum power density and maximum current density in MFCs with PC and those with Nafion PEMs. Moreover, a higher average current generation was observed in MFCs with PC ($104.3{\pm}15.3A/m^3$) compared with MFCs with Nafion PEM ($100.4{\pm}17.7A/m^3$), as well as showing insignificant degradation of the PC surface, during 177 days of use in swine wastewater. These results suggest that PC separators could serve as a low-cost alternative to Nafion PEMs for construction of cost-effective MFCs.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1998.02a
• /
• pp.24-24
• /
• 1998

반도체장비를 포함하는 초고진공장비의 園훌化가 급속히 그리고 절실히 요구되고 있는 것이 현실정이다. 當面해서 실현할 국산진공장비의 대상은 廣範圍하다. 즉, 각종 진공 pump ( (rotary, dry, diffusion, cryo, ion, turbo melecular pump), 진공 chamber, 진공 line, gate valve 를 위 시 한 진공 V머ve, flange, gasket, fl않d야lU, mainpulater 퉁 진공 部品이 다. 진공계 의 핵심 은 適切하고 優良한 진공재료의 선태파 사용이다. 진공장비는 사용자가 원하는 진공도를 원하 는 시간 동안 륨空度를 유지해 주어야 한다. 진공재료 선태의 기준사항은:(1) 기체의 透過성 (2) 薰했훌 (3) 혔體放出특성 - -outgassing과 degassing- (4) 機械的 량훌度 (5) 온도 의존성 (6) 化學톡성 (7) 加I성 및 鎔接 성 (8) 課電특성 (9) 磁氣특성 (10) 高速함子 및 放射線 특성 (11) 經濟성 및 調達생 둥이 다. 우량한 초고진공계재료는 풍부하게 개발되어 왔고, 또 新材料들이 개발되고 있다. 여기에서는 주로 초고진공 내지는 극고진공계의 構造材料, 機能材料, 部品材料 일반파 몇가지 신재료의 특 성에 관해서 記述한다. M Mild SteeHSAE, 1112, 1010, 1020, 1022, etc)., S Stainless SteeHAlSI, 304, 304L, 310, 316, 321, 347): 구조재료, chamber, fl하1ges A Aluminum과 Alloys (1060, 1100, 2014, 4032, 6(뻐1): 구조재료, chamber, flanges, gaskets A AI, Al 떠loy는 SS에 代替하는 역 할올 시 작하고 있다. C Copper, Copper Alloys(C11$\alpha$)0, C26800, C61400, Cl7200): 내장인자, gasket, cryopanel, tubing T Titanium, Ziriconium, Haf띠um 및 Alloys: 특히 Ti은 10n pump 용 getter material 이 외 에 U UHV,XHV용 chamber계로서 관심올 끌고 있다. N Nickel, Nickel Alloys (200, 204, 211, monel, nichrome): 부식 방지 , 전자장치 , 자기 장치 귀 금속(Ag, Au, Pt, Pd, Rh, Ir, Os, Ru): 보조부품, gasket, filament, coating, thermocouple, 접 합부위 T TiC, SiC, zrC, HfC, TaC 둥의 탄화물과, BN, TiN, AlN 동의 질화물, 붕화물이 둥장하고 었 다. 유리: Soda Lime, Borosilicate, Potash Soda Lead: View Port, Chamber envelope C Ceramics: AlZ03, BeO, MgO, zrOz, SiOz, MgOzSiOz, 3Alz032SiOz, Z$textsc{k}$hSiOz S상N4: e electrical, thermal insulators, crucibles, boats, single crystals, sepctr려 windows 저자는 최근 저자들이 발견한 Zr-Ti-Cu-Ni-Be amorphous alloys coated cham뾰r가 radiation p proof로 이용될 수 있는 사실을 점검하고 었다 .. Z.Y. Hua 들은 Cs3Sb를 새로운 photocathode 재료로 보고하고 있다.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.71-71
• /
• 2011

Dye-sensitized solar cells (DSCs) have drawn great academic attention due to their potential as low-cost renewable energy sources. DSCs contain a nanostructured TiO2 photoanode, which is a key-component for high conversion efficiency. Particularly, one-dimensional (1-D) nanostructured photoanodes can enhance the electron transport for the efficient collection to the conducting substrate in competition with the recombination processes. This is because photoelectron colletion is determined by trapping/detrapping events along the site of the electron traps (defects, surface states, grain boundaries, and self-trapping). Therefore, 1-D nanostructured photoanodes are advantageous for the fast electron transport due to their desirable features of greatly reduced intercrystalline contacts with specified directionality. In particular, anodic TiO2 nanotube (NT) electrodes recently have been intensively explored owing to their ideal structure for application in DSCs. Besides the enhanced electron transport properties resulted from the 1-D structure, highly ordered and vertically oriented nanostructure of anodic TiO2 NT can contribute additional merits, such as enhanced electrolyte diffusion, better interfacial contact with viscous electrolytes. First, to confirm the advantages of 1-D nanostructured material for the photoelectron collection, we compared the electron transport and charge recombination characteristics between nanoparticle (NP)- and nanorod (NR)-based photoanodes in DSCs by the stepped light-induced transient measurements of photocurrent and voltage (SLIM-PCV). We confirmed that the electron lifetime of the NR-based photoanode was much longer than that of the NP-based photoanode. In addition, highly ordered and vertically oriented TiO2 NT photoanodes were prepared by electrochemical anodization method. We compared the photovoltaic properties of DSCs utilizing TiO2 NT photoanodes prepared by one-step anodization and two-step anodization. And, to reduce the charge recombination rate, energy barrier layer (ZnO, Al2O3)-coated TiO2 NTs also applied in DSC. Furthermore, we applied the TiO2 NT photoanode in DSCs using a viscous electrolyte, i.e., cobalt bipyridyl redox electrolyte, and confirmed that the pore structure of NT array can enhance the performances of this viscous electrolyte.

• Applied Chemistry for Engineering
• /
• v.21 no.3
• /
• pp.265-271
• /
• 2010

Desalination effects of capacitive deionization (CDI) process was studied using $TiO_2$/activated carbon electrode. In order to enhance the wettability of electrode and decrease a electrode resistance, $TiO_2$ was coated on activated carbon. By means of $TiO_2$ coating on activated carbon, electric double layer to adsorption content in CDI process was increased. It was identified from TEM, XRD, and XPS that the activated carbon based on $TiO_2$ composite was fabricated successfully by means of sol-gel method. As a results of cyclic voltammetry and impedance, it was identified that $TiO_2$/activated carbon electrode has more electric double later capacitance and less diffusion resistance than activated carbon. Also charge-discharge and ion conductivity profiles showed that the ion removal ratios of $TiO_2$/activated carbon electrode in NaCl electrolyte of $1000\;{\mu}S/cm$ more increased about 39% than that of activated carbon. In conclusion it was possible to identify that the carbon electrode coated $TiO_2$ as electrode material was more effective than raw carbon electrode.

• Journal of dental hygiene science
• /
• v.8 no.4
• /
• pp.367-373
• /
• 2008

The natural products are used to be development of new antibacterial substances against human pathogenic bacteria. Adherence to the tooth surface by S. mutans is an important step in initiation of dental caries. This study was to examine antibacterial activity and anti-adhesive effect of Scutellaria baicalensis extract against S. mutans. Extracts of S. baicalensis were tested for antimicrobial activities by paper disc methods and radial diffusion assay methods, and bacterial adherence assay using 3 type of hydroxyapatite. The antibacterial level of ethyl acetate extract, IPK-3 on the growth of S. mutans was 125 mg/ml of minimum inhibitory concentration (MIC). The maximum growth of S. mutans in medium added with IPK-3 extract (50 mg/ml) was delayed to 30 hr, while the highest at 24 hr in control medium. The pH values of the control medium was 5.63 at 18 hr, but the media supplemented with IPK-3 extract was pH 6.50 at 12 hr. In adhesive inhibition assay, S. mutans was labelled with the fluorescent indicator DAPI and measured with fluorescence microscope. Adhesion of S. mutans on hydroxyapatite beads was inhibited by IPK-3 extracts. These results suggest that S. baicalensis extract can be used as an effective material for antibacterial activity and adhesive inhibition against S. mutans.

• Journal of Digital Convergence
• /
• v.10 no.11
• /
• pp.691-699
• /
• 2012

"Information", which is circulated in society by information technology development represented by computer, has brought innovation not only to physical civilization, but also deep into our daily lives. This is to say that information has brought fundamental change to its form of existence, and value system through being faster regarding the circulation and the way of management being diverse. As time goes by, this kind of change would stimulate more changes to be made as the development of scientific civilization. Therefore, informatization is one of the important characteristic that defines modern society's essence, but on the other side, information has been taken advantage of that temperament and abused in a lot of different ways. "The Law Regarding Computer Network Diffusion Expansion and Usage Promotion"(1986), as a counterplan of informatization is our nation's first Act about informatization, which enacts national policy and system about this issue. Since then, many laws has been enacted down to "Private Information Protection Act"(2011), forming a comprehensive system. The basic background of these laws are based upon the premise that even if the place where the information is managed is virtual space, rules that are considered valid in the real world should be basically applied in the virtual space. Therefore, the violation of the law in the real world is also considered the violation in the virtual space. This direction of current law regarding information is shared with both the theories and the reality. However, current law system and notion are based upon the premise that the law regards material objects, thus the characteristic of the information, which is "Immaterial Being" is not reflected. Also, the management and approach to this issue is allopathic, exposing many problems. Thus, this paper examines the way of protecting information stipulated in the current law, contemplates its protection scope and limitation, and seeks the direction of the improvement, based on the critical mind explained above.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.585-588
• /
• 2008

To predict the service life of reinforced concrete structures exposed to chloride environment, quantitative measures of material properties such as the critical chloride content for corrosion in concrete and the diffusion coefficient of chloride ions of concrete and the surface chloride content of the concrete are essential. However, it should be noted that they are influenced by several factors such as concrete mix proportions, cement type, and environmental conditions, etc. Thus, the purpose of this research is to estimate more actually the critical chloride content for corrosion of the reinforcing steel in concrete by field exposure experiment. For this purpose, the prism concrete test specimens were made for water-cement(W/C) ratios of 31%, 42%, 50%, and 70%, and then the field exposure experiment for them were conducted at Youngduk of the east coast for about 3 years. During the test, corrosion monitoring by half cell potential method was carried out to detect the time to initiation of corrosion for test specimens and its chloride content was evaluated by breaking the concrete test specimens when corrosion of the reinforcing steel in concrete was perceived. It was observed from the test results that the critical chloride content for corrosion of reinforcing steel in concrete would be dependent on W/C ratio and almost irrespective of concrete cover.

• Nuclear Engineering and Technology
• /
• v.21 no.2
• /
• pp.89-98
• /
• 1989

The expanding copper mandrel test performed at three strain rates (3.2$\times$10E -5/s, 2.0$\times$10E-6/s and 1.2$\times$10E-7/s) over 553-873 K temperature range by varying the heating rates (8-1$0^{\circ}C$/s, 1-2$^{\circ}C$/s and 0.5$^{\circ}C$/s) in air and in vacuum (5$\times$10E-5 torr). The yield stress peak, the strain rate sensitivity minimum and the activation volume peaks could be explained in terms of the dynamic strain aging. The activation energy for dynamic strain aging obtained from the yield stress peak temperature and strain rate was 196 KJ/mol and this value was in good agreement with the activation energy for oxygen diffusion in $\alpha$-zirconium and Zircaloy-2 (207-220 KJ/mol). Therefore, oxygen atoms are responsible for the dynamic strain aging which appeared between 573 K and 673 K. The yield stress increase due to the oxidation was obtained by comparing the yield stress in air with that in vacuum and represented by the percentage increase of yield stress ( $\sigma$$^{a}$ $_{y}$ - $\sigma$$^{v}$ $_{y}$ / $\sigma$$^{v}$ $_{y}$ ). The slower the strain rate, the greater the percentage increase occurs. In order to estimate the yield stress of PWR fuel cladding material under the service environment, the yield stress in water was obtained by comparing the oxidation rate in air that in water assuming the relationship between the oxygen pick-up amount and the yield stress increase.

• Journal of Korea Water Resources Association
• /
• v.53 no.11
• /
• pp.999-1013
• /
• 2020

Weather modification research has been actively performed worldwide, but a technology that can more quantitatively prove the research effects are needed. In this study, the seeding effect, the efficiency of precipitation enhancement in weather modification experiment, was verified using the radar data. Also, the effects of seeding material on hydrometeor change was analyzed. For this, radar data, weather conditions, and numerical simulation data for diffusion were applied. First, a method to analyze the seeding effect in three steps was proposed: before seeding, during seeding, and after seeding. The proposed method was applied to three cases of weather modification experiments conducted in Gangwon-do and the West Sea regions. As a result, when there is no natural precipitation, the radar reflectivity detected in the area where precipitation change is expected was determined as the seeding effect. When natural precipitation occurs, the seeding effect was determined by excluding the effect of natural precipitation from the maximum reflectivity detected. For the application results, it was found that the precipitation intensity increased by 0.1 mm/h through the seeding effect. In addition, it was confirmed that ice crystals, supercooled water droplets, and mixed-phase precipitation were distributed in the seeding cloud. The results of these weather modification research can be used to secure water resources as well as for future study of cloud physics.

• Membrane Journal
• /
• v.21 no.4
• /
• pp.360-366
• /
• 2011

The effect of cross-flow velocity and transmembrane pressure (TMP) on membrane fouling was observed from pilot-scale operation of thermophilic anaerobic membrane bioreactor (AnMBR) treating food waste leachate. It was found that fouling rate was reduced significantly as cross-flow velocity increased at constant TMP mode of operation while this effectiveness was more pronounced at lower TMP. Higher TMP resulted in less permeable fouling layer possibly due to compressibility of foulant material on membrane surface. Particle sizes of membrane concentrate ranged from 10 to $100{\mu}m$, implying that shear-induced diffusion enhance back transport of these particle sizes away from the membrane effectively. From the continuous operation of AnMBR, it was confirmed that shear rate played an important role in the reduction of membrane fouling. Membrane autopsy works at the end of operation of AnMBR showed clearly that both organic and inorganic fouling were significant on membrane surface. Surface shear by cross-flow velocity was expected to be less effective to remove irreversible fouling which can be mainly caused by the adsorption of organic colloidal materials into membrane pores.