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A reactor system combining reductive dechlorination with co-metabolic oxidation for complete degradation of tetrachloro-entylene

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Journal of Environmental Sciences 2002年第4期14卷 445-450页

作者： tae HO lee MICHIHIKO IKE MASANORI FUJITA Department of Environmental Engineering Osaka University 2-1 YamadaokaDepartment of Environmental Engineering Osaka University 2-1 YamadaokaDepartment of Environmental Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan.Suit

A laboratory sequential anaerobic aerobic bioreactor system, which consisted of an anaerobic fixed film reactor and two aerobic chemostats, was set up to degrade tetrachloroethylene (PCE) without accumulating highly toxic degradation intermediates. A soil enrichment culture, which could reductively dechlorinate 900 μM (ca. 150 mg/L) of PCE stoichiometrically into cis 1,2 dichloroethylene ( cis DCE), was attached to ceramic media in the anaerobic fixed film reactor. A phenol degrading strain, Alcaligenes sp. R5, which can efficiently degrade cis DCE by co metabolic oxidation, was used as inoculum for the aerobic chemostats consisted of a transformation reactor and a growth reactor. The anaerobic fixed film bioreactor showed more than 99 % of PCE transformation into cis DCE in the range of influent PCE concentration from 5 μM to 35 μM at hydraulic retention time of 48h. On the other hand, efficient degradation of the resultant cis DCE by strain R5 in the following aerobic system could not be achieved due to oxygen limitation. However, 54% of the maximum cis DCE degradation was obtained when 10 μmol of hydrogen peroxide (H 2O 2) was supplemented to the transformation reactor as an additional oxygen source. Further studies are needed to achieve more efficient co metabolic degradation of cis DCE in the aerobic reactor.

关键词： anaerobic aerobic bioreactor co oxidation reductive dechlorination tetrachloroethylene

Electrochemically metal-doped reduced graphene oxide films:Properties and applications

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Journal of Materials Science & Technology 2020年第5期40卷 72-80页

作者： Myung-Sic Chae tae Ho lee Kyung Rock Son tae Hoon Park Kyo Seon Hwang tae Geun Kim School of Electrical Engineering Korea UniversityAnam-ro 145Seongbuk-guSeoul 02841South Korea Department of Clinical Pharmacology and Therapeutics College of MedicineKyung Hee UniversitySeoul 02447South Korea

The fine control of doping levels in graphene materials such as reduced graphene oxide(RGO)is important to properly manipulate their ambipolar transport characteristics for various device ***,conventional doping methods involve complex chemical reactions,large-scale doping processes,and poor ***,a simple and controllable electrochemical doping treatment(EDT),performed via the conductive channels created at the RGO surface by the application of an electric field,is introduced to tailor the electrical properties of RGO films.X-ray photoelectron spectroscopy and Raman spectroscopy measurements are performed to detect the presence of Ni atoms in RGO films after the EDT(EDT-RGO).Then,EDT-RGO field-effect transistors(FETs)are fabricated with different doping areas(0 to 100%fractional area)on the RGO active channel to investigate the effect and selective-area doping capability of the *** to p-type doping compensation by the intercalated Ni atoms,the electron mobility of the EDT-RGO FET decreases from 1.40 to 0.12 cm2 V-1s-1 compared with that of the undoped RGO-FET,leading to the conversion from ambipolar to unipolar p-type transfer characteristics.

关键词： Reduced graphene oxide Electrochemical doping treatment Electrical breakdown process Field-effect transistor

Interface engineering of an electrospun nanofiber-based composite cathode for intermediate-temperature solid oxide fuel cells

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International Journal of Extreme Manufacturing 2023年第1期5卷 345-353页

作者： Seo Ju Kim Deokyoon Woo Donguk Kim tae Kyeong lee Jaeyeob lee Wonyoung lee School of Mechanical Engineering Sungkyunkwan UniversitySuwonKyunggi-do 16419Republic of Korea SKKU Institute of Energy Science and Technology(SIEST) Sungkyunkwan UniversitySuwon 16419Republic of Korea

Sluggish oxygen reduction reaction(ORR)kinetics are a major obstacle to developing intermediate-temperature solid-oxide fuel cells(IT-SOFCs).In particular,engineering the anion defect concentration at an interface between the cathode and electrolyte is important for facilitating ORR kinetics and hence improving the electrochemical *** developed the yttria-stabilized zirconia(YSZ)nanofiber(NF)-based composite cathode,where the oxygen vacancy concentration is controlled by varying the dopant cation(Y2O3)ratio in the YSZ *** composite cathode with the optimized oxygen vacancy concentration exhibits maximum power densities of 2.66 and 1.51 W cm^(−2)at 700 and 600℃,respectively,with excellent thermal stability at 700℃ over 500 h under 1.0 A cm^(−2).Electrochemical impedance spectroscopy and distribution of relaxation time analysis revealed that the high oxygen vacancy concentration in the NF-based scaffold facilitates the charge transfer and incorporation reaction occurred at the interfaces between the cathode and *** results demonstrate the high feasibility and potential of interface engineering for achieving IT-SOFCs with higher performance and stability.

关键词： solid oxide fuel cells nanofiber infiltration oxygen reduction reactions oxygen vacancy

Analysis of Determinants for an Enhanced and Long-lasting Coastal Convective System by Means of a Case Study(26 July 2011)

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Advances in Atmospheric Sciences 2019年第12期36卷 1327-1339页

作者： Jung-tae lee Dong-In lee Shingo SHIMIZU Cheol-Hwan YOU New and Renewable Energy Resource Center Korea Institute of Energy ResearchDaejeon 34129Republic of Korea Department of Environmental Atmospheric Science Pukyong National UniversityBusan 48513Republic of Korea Storm Floodand Landslide Research DepartmentNational Research Institute for Earth Science and Disaster ResilienceTsukuba 305-0006Japan

A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for this nearshore convective system are investigated from observations and the results of model experiments. Three-dimensional radar fields clearly show that a change of wind at the surface border played an important role in the development of the nearshore convection system. The simulation results, which are very similar to the observations, show that the surface border generated and maintained the convergence zone. The roughness change enhanced the convergence, and the interaction between the deepening cold pool and downward flow maintained the convergence zone. The surface mechanical discontinuity affected by the roughness change between sea and land formed the convergence (gradient of wind stress), which induced momentum transfer to the upper layer. The cold pool created a steep gradient of potential temperature and provided the reason for the propagated convergence zone with the downward flow. The maximum value of the surface change factor, which comprises the influencing factors for the long-lasting convective system, reflects the enhancement of the system at the coast.

关键词： coastal precipitation roughness convergence zone cold pool propagation downward flow

Adaptive Functional Projective Lag Synchronization of a Hyperchaotic Rossler System

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Chinese Physics Letters 2009年第9期26卷 69-72页

作者： tae H. lee Ju H. Park Nonlinear Dynamics Group Department of Electrical Engineering Yeungnam University 214-1 Dae-Dong Kyongsan 712-749 Republic of Korea

We explain the functional projective lag synchronization of a hyperchaotic Rossler system with four unknown parameters, where the output of the master system lags behind the output of the slave system proportionally. Based on Lyapunov stability theory, an active control method and adaptive control law are employed to make the states of two hyperchaotic Rossler systems asymptotically synchronized. Finally, some numerical examples are provided to show the effectiveness of our results.

关键词： No English Keyword

Discovering High-Quality Threaded Discussions in Online Forums

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Journal of Computer Science & Technology 2014年第3期29卷 519-531页

作者： Jung-tae lee Min-Chul Yang Hae-Chang Rim Department of Computer and Radio Communications Engineering Korea UniversitySeoul 136-713Korea

Archives of threaded discussions generated by users in online forums and discussion boards contain valuable knowledge on various topics. However, not all threads are useful because of deliberate abuses, such as trolling and flaming, that are commonly observed in online conversations. The existence of various users with different levels of expertise also makes it difficult to assume that every discussion thread stored online contains high-quality contents. Although finding high-quality threads automatically can help both users and search engines sift through a huge amount of thread archives and make use of these potentially useful resources effectively, no previous work to our knowledge has performed a study on such task. In this paper, we propose an automatic method for distinguishing high-quality threads from low-quality ones in online discussion sites. We first suggest four different artificial measures for inducing overall quality of a thread based on ratings of its posts. We then propose two tasks involving prediction of thread quality without using post rating information. We adopt a popular machine learning framework to solve the two prediction tasks. Experimental results on a real world forum archive demonstrate that our method can significantly improve the prediction performance across all four measures of thread quality on both tasks. We also compare how different types of features derived from various aspects of threads contribute to the overall performance and investigate key features that play a crucial role in discovering high-quality threads in online discussion sites.

关键词： online forum discussion board thread quality

High resolution impedance manometric findings in dysphagia of Huntington's disease

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World Journal of Gastroenterology 2012年第14期18卷 1695-1699页

作者： tae Hee lee Joon Seong lee Wan Jung Kim Institute for Digestive Research Soon Chun Hyang College of MedicineSeoul 140-743South Korea

Conventional manometry presents significant challenges,especially in assessment of pharyngeal swallowing,because of the asymmetry and deglutitive movements of oropharyngeal *** only provides information about intraluminal pressure and thus it is difficult to study functional details of esophageal motility *** technology of solid high resolution impedance manometry(HRIM),with 32 pressure sensors and 6 impedance sensors,is likely to provide better assessment of pharyngeal swallowing as well as more information about esophageal motility ***,the clinical usefulness of application of HRIM in patients with oropharyngeal dysphagia or esophageal dysphagia is not *** experienced a case of Huntington's disease presenting with both oropharyngeal and esophageal dysphagia,in which HRIM revealed the mechanism of oropharyngeal dysphagia and provided comprehensive information about esophageal dysphagia.

关键词： Dysphagia Esophagus High resolution impedance manometry Huntington's disease Oropharynx

Mechanical properties of high-strength concrete subjected to high temperature by stressed test

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中国有色金属学会会刊：英文版 2009年第B9期19卷 128-133页

作者： Gyu-Yong KIM Young-Sun KIM tae-Gyu lee Division of Architecture Engineering Chun gnam National University

Recently, the effects of high temperature on compressive strength and elastic modulus of high strength concrete were experimentally investigated. The present study is aimed to study the effect of elevated temperatures ranging from 20 ℃ to 700 ℃ on the material mechanical properties of high-strength concrete of 40, 60 and 80 MPa grade. During the strength test, the specimens are subjected to a 25% of ultimate compressive strength at room temperature and sustained during heating, and when the target temperature is reached, the specimens are loaded to failure. The tests were conducted at various temperatures (20-700 ℃) for concretes made with W/B ratios of 46%, 32% and 25%, respectively. The results show that the relative values of compressive strength and elastic modulus decrease with increasing compressive strength grade of specimen.

关键词：高强混凝土高温作用力学性能测试抗压强度温度升高弹性模量强度试验

Endoscopic prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis

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World Journal of Gastroenterology 2014年第44期20卷 16582-16595页

作者： tae Hoon lee Do Hyun Park Division of Gastroenterology Department of Internal Medicine Soonchunhyang University School of Medicine Cheonan Hospital Division of Gastroenterology Department of Internal Medicine University of Ulsan College of Medicine Asa Medical Center

Post-endoscopic retrograde cholangiopancreatography(ERCP) pancreatitis(PEP) is not an uncommon adverse event but may be an avoidable complication. Although pancreatitis of severe grade is reported in 0.1%-0.5% of ERCP patients, a serious clinical course may be lethal. For prevention of severe PEP, patient risk stratification, appropriate selection of patients using noninvasive diagnostic imaging methods such as magnetic resonance cholangiopancreatography or endoscopic ultrasonography(EUS), and avoidance of unnecessary invasive procedures, are important measures to be taken before any procedure. Pharmacological prevention is also commonly attempted but is usually ineffective. No ideal agent has not yet been found and the available data conflict. Currently, rectal non-steroidal anti-inflammatory drugs are used to prevent PEP in high-risk patients, but additional studies using larger numbers of subjects are necessary to confirm any prophylactic effect. In this review, we focus on endoscopic procedures seeking to prevent or decrease the severity of PEP. Among various cannulation methods, wire-guided cannulation,precut fistulotomy,and transpancreatic septostomy are *** pancreatic stent placement,which is the best-known prophylactic method,is reviewed with reference to the ideal stent type,adequate duration of stent placement,and stentrelated ***,we comment on other treatment alternatives,and make the point that further advances in EUS-guided techniques may afford useful PEP prophylaxis.

关键词： Endoscopic retrograde cholangiopancreatography Prevention Pancreatitis Pancreas stent Cannulation Fistulotomy