내변형 폴리머 개질 아스팔트 혼합물의 개발

김광우,도영수,정규동,조희원,안경애,이상범 강원대학교 석재복합신소재제품연구센터 1997 석재연 논문집 Vol.2 No.-

본 연구에서는 국내산 LDPE 및 SBS 폴리머를 아스팔트 함량의 3%, 4%, 5%와 카본블랙을 10% 사용하여 AP-3 아스팔트를 개질한 화강암, 편마암, 석회암 혼합물을 제조하고 그 특성의 변화를 고찰하였다. 폴리머는 3가지 골재 혼합물 모두에 전반적으로 인장강도와 강성의 증가를 가져오는 것으로 나타났다. 그러나 그중 편마암에서는 그 효과가 비교적 적고 화강암과 석회암에 더 큰 것으로 나타났다. 또한 두 폴리머간 개질효과의 차이는 거의 없었으나 LDPE가 약간 높게 나타나 보였다. 카본 블랙의 사용은 폴리머 개질 혼합물의 경우에는 별로 효과적이지 못하였으나, 일반혼합물의 경우는 아스팔트의 강도특성에 영향을 미침임을 알 수 있었다. SBS and LDPE polymers with contents of 3%, 4%, 5% and a carbon black with content of 10% by wt. of asphalt were used in three aggregate mixtures, a gneiss, a granite and a limestone waste aggregates. Indirect tensile strength and stiffness index were evaluated for each mixture. The two polymers were effective on improving those strength characteristics for all three aggregate mixtures. Especially, limestone and granite aggregates were improved more than gneiss. Among two polymers, there were almost no difference in performance even though LDPE showed a little higher values. Carbon black improved the properties of plain asphalt mixtures, although it was not the case for the PMA mixtures.

Default Prediction for Real Estate Companies with Imbalanced Dataset

( Xiang Dong Yuan ),( Zhi Xiao ),( Xue Xiao ) 한국정보처리학회 2014 Journal of information processing systems Vol.10 No.2

When analyzing default predictions in real estate companies, the number of non-defaulted cases always greatly exceeds the defaulted ones, which creates the twoclass imbalance problem. This lowers the ability of prediction models to distinguish the default sample. In order to avoid this sample selection bias and to improve the prediction model, this paper applies a minority sample generation approach to create new minority samples. The logistic regression, support vector machine (SVM) classification, and neural network (NN) classification use an imbalanced dataset. They were used as benchmarks with a single prediction model that used a balanced dataset corrected by the minority samples generation approach. Instead of using prediction oriented tests and the overall accuracy, the true positive rate (TPR), the true negative rate (TNR), G-mean, and F-score are used to measure the performance of default prediction models for imbalanced dataset. In this paper, we describe an empirical experiment that used a sampling of 14 default and 315 non-default listed real estate companies in China and report that most results using single prediction models with a balanced dataset generated better results than an imbalanced dataset.

Identifying a Cinnamoyl Coenzyme A Reductase (CCR) Activity with 4-Coumaric Acid: Coenzyme A Ligase (4CL) Reaction Products in Populus tomentosa

Dong-Dong Wang,Hua Bai,Wei-Qi Chen,Hai Lu,Xiang-Ning Jiang 한국식물학회 2009 Journal of Plant Biology Vol.52 No.5

A cinnamoyl coenzyme A reductase (CCR, EC 1.2.1.44), one of the key enzyme involved in lignin biosynthesis, was cloned from Populus tomentosa (Chinese white poplar). At the same time, a 4CL1 gene was cloned from P. tomentosa, too. The two genes were subcloned in pQE31 vector and expressed in Escherichia coli M15. Both of them were purified by Ni-NTA. Purified CCR protein was digested by trypsin and analyzed by HPLC-MS; the peptide segments had 27% similarity with the sequence of the CCR protein. 4CL was thought to be a neighbor enzyme of CCR in lignin biosynthesis. In this paper, a 4CL1 from P. tomentosa was cloned, and its enzyme reaction products were extracted for the substrates of CCR. Three 4CL1 enzyme reaction products were monitored by HPLC-MS and then the CCR enzyme reaction was detected by GC-MS. In the CCR reaction, the three corresponding aldehyde (p-coumaraldehyde, caffealdehyde, and coniferaldehyde) were detected and identified by Frontier3 software. The results showed that the CCR that we cloned from P. tomentosa had affinities with 4CL1 enzyme reaction products and a ptCCR that was cloned from aspen (Li et al., Plant Cell Physiol 46(7):1073–1082, 2005) only had affinity with feruloyl-CoA. The different results maybe depend on the different study method. The method of exacting 4CL enzyme products as the substrates of CCR in the paper was reliable and can be used in lignin biosynthesis network to detect the enzymes in the neighborhood that depended on the polarity of the substrates and products. This CCR gene had eight homology sequence CCR gene when a BLAST was conducted in Populus trichocarpa genome database. The CCR homology genes in Populus suggested that some CCRs may take part in the lignin biosynthesis, too. The gene family would be the hot spot in the future study.

One-step hydrothermal synthesis of Ag decorated TiO₂ nanoparticles for dye-sensitized solar cell application

Dong, Yong Xiang,Wang, Xuan Liang,Jin, En Mei,Jeong, Sang Mun,Jin, Bo,Lee, See Hoon Elsevier 2019 RENEWABLE ENERGY Vol.135 No.-

<P><B>Abstract</B></P> <P>Over the past few years, many efforts have been made to develop efficient visible light-activated photovoltaic materials. In this study, the Ag-TiO<SUB>2</SUB> nanoparticles were synthesized by using the hydrothermal method. Ag-TiO<SUB>2</SUB> nanoparticles showed significantly higher visible light absorption and better photovoltaic activity than anatase TiO<SUB>2</SUB>. TiO<SUB>2</SUB> nanoparticles were decorated with different concentrations of Ag to improve their photovoltaic properties. All the as-prepared TiO<SUB>2</SUB> and Ag-TiO<SUB>2</SUB> nanoparticles showed a pure anatase crystalline structure. In addition, the Ag-doped nanoparticles showed broader absorption edges (which shifted to higher wavelengths) than the undoped nanoparticles. The solar conversion efficiency (<I>η</I>) of 0.1M Ag-decorated (Ag<SUB>0.1</SUB>-TiO<SUB>2</SUB>) nanoparticle-based dye-sensitized solar cell (DSSC) was 6.44%, which is ∼22% higher than that of the TiO<SUB>2</SUB> nanoparticle-based DSSC (<I>η</I> of 5.05%).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A hydrothermal method has been used to synthesize Ag-doped TiO<SUB>2</SUB> (Ag-TiO<SUB>2</SUB>) nanoparticles. </LI> <LI> Ag-TiO<SUB>2</SUB> nanoparticles showed high visible light absorption in the visible spectral region. </LI> <LI> Ag-TiO<SUB>2</SUB> nanoparticles showed high photocurrent density (<I>J</I> <SUB> <I>sc</I> </SUB>) and solar conversion efficiency (<I>η</I>). </LI> <LI> Ag doping increased the solar conversion efficiency by 22% than anatase TiO<SUB>2</SUB>. </LI> </UL> </P>

Aster saponin A2 inhibits osteoclastogenesis through mitogen-activated protein kinase-c-Fos-NFATc1 signaling pathway

Xiang-Dong Su,Seo Y Yang,Saroj K Shrestha,Yunjo Soh 대한수의학회 2022 Journal of Veterinary Science Vol.23 No.4

Background: In lipopolysaccharide-induced RAW264.7 cells, Aster tataricus (AT) inhibits the nuclear factor kappa-light-chain-enhancer of activated B cells and MAPKs pathways and critical pathways of osteoclast development and bone resorption. Objectives: This study examined how aster saponin A2 (AS-A2) isolated from AT affects the processes and function of osteoclastogenesis induced by receptor activator of nuclear factor kappa-B ligand (RANKL) in RAW264.7 cells and bone marrow macrophages (BMMs). Methods: The cell viability, tartrate-resistant acid phosphatase staining, pit formation assay, polymerase chain reaction, and western blot were carried out to determine the effects of AS-A2 on osteoclastogenesis. Results: In RAW264.7 and BMMs, AS-A2 decreased RANKL-initiated osteoclast differentiation in a concentration-dependent manner. In AS-A2-treated cells, the phosphorylation of ERK1/2, JNK, and p38 protein expression were reduced considerably compared to the control cells. In RAW264.7 cells, AS-A2 suppressed the RANKL-induced activation of osteoclast-related genes. During osteoclast differentiation, AS-A2 suppressed the transcriptional and translational expression of NFATc1 and c-Fos. AS-A2 inhibited osteoclast development, reducing the size of the bone resorption pit area. Conclusion: AS-A2 isolated from AT appears to be a viable therapeutic therapy for osteolytic illnesses, such as osteoporosis, Paget’s disease, and osteogenesis imperfecta.

Mechanically Controllable Break Junctions for Molecular Electronics

Xiang, Dong,Jeong, Hyunhak,Lee, Takhee,Mayer, Dirk WILEY‐VCH Verlag 2013 ADVANCED MATERIALS Vol.25 No.35

<P><B>Abstract</B></P><P>A mechanically controllable break junction (MCBJ) represents a fundamental technique for the investigation of molecular electronic junctions, especially for the study of the electronic properties of single molecules. With unique advantages, the MCBJ technique has provided substantial insight into charge transport processes in molecules. In this review, the techniques for sample fabrication, operation and the various applications of MCBJs are introduced and the history, challenges and future of MCBJs are discussed.</P>

Fuzzy-Logic-Based <tex> $V/f$</tex> Control of an Induction Motor for a DC Grid Power-Leveling System Using Flywheel Energy Storage Equipment

Xiang-Dong Sun,Kang-Hoon Koh,Byung-Gyu Yu,Matsui, M. IEEE 2009 IEEE transactions on industrial electronics Vol.56 No.8

<P>Since natural distribution power generation systems such as wind energy contain electric power fluctuation, flywheel energy storage (FWES) equipment for power compensation is used. Fuzzy-logic-based <I>V</I>/<I>f</I> control of the induction motor is proposed for the speed sensorless power-leveling system in this paper. Only two sensors, including one DC voltage sensor and one DC current sensor, are utilized. The flywheel is composed of two modes, namely, the speed picking-up control mode and the power control mode. According to the DC-link average current of an inverter, the rotating speed of the flywheel in the speed picking-up control mode is detected by regulating the output frequency and the output voltage based on fuzzy logic control. The power control mode consists of the outer voltage loop and the inner current loop. Although the outer loop is also realized by fuzzy logic control, the inner loop is the key object in this paper, i.e., the proportional and integral gains of a proportional-integral regulator are optimized by means of fuzzy logic reasoning for the purpose of the reliability and rapid response of leveling power. The experiments are carried out with the FWES equipment of 40-kJ energy, and the results verify that the proposed method is reliable, and better dynamic and static performance is demonstrated.</P>

Three-Terminal Single-Molecule Junctions Formed by Mechanically Controllable Break Junctions with Side Gating

Xiang, Dong,Jeong, Hyunhak,Kim, Dongku,Lee, Takhee,Cheng, Yongjin,Wang, Qingling,Mayer, Dirk American Chemical Society 2013 Nano letters Vol.13 No.6

<P>Molecules are promising candidates for electronic device components because of their small size, chemical tunability, and ability to self-assemble. A major challenge when building molecule-based electronic devices is forming reliable molecular junctions and controlling the electrical current through the junctions. Here, we report a three-terminal junction that combines both the ability to form a stable single-molecule junction via the mechanically controllable break junction (MCBJ) technique and the ability to shift the energy levels of the molecule by gating. Using a noncontact side-gate electrode located a few nanometers away from the molecular junction, the conductance of the molecule could be dramatically modulated because the electrical field applied to the molecular junction from the side gate changed the molecular electronic structure, as confirmed by the ab initio calculations. Our study will provide a new design for mechanically stable single-molecule transistor junctions fabricated by the MCBJ method.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-6/nl401067x/production/images/medium/nl-2013-01067x_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl401067x'>ACS Electronic Supporting Info</A></P>

A Novel Islanding Detection Method Based on Minute Asymmetrical Current Injection for Three-Phase Grid-Connected PV Inverters

Xiang-Dong Sun,Mikihiko Matsui,Byung-Gyu Yu 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-

An active anti-islanding method based on the current control for a three-phase grid-connected PV inverter is proposed in this paper. The current of phase a is synchronous with the corresponding voltage at the common coupling point in its positive half cycle, and a zero-current zone is inserted into the end of the cycle in a negative half cycle. As for phase c, the zero-current zone is inserted in the positive half cycle of the current, and the current of phase c in a negative half cycle is synchronous with the corresponding voltage. Therefore the currents of phase a and c in one cycle become asymmetrical slightly. Before the islanding takes place, because of the operation of utility voltage the positive and negative half cycles of three-phase voltages are symmetrical. While the islanding occurs, the time differences between the positive and negative half cycles of the voltages of phase a and c will generate and the islanding is detected in accordance with the repetitive cycles fulfilling the conditions of the time differences. On the basis of the above analysis for three-phase four-wire power systems, three-phase three-wire systems are designed. The experiment on a 0.3㎾ PV inverter system connected to 200V/50㎐ utility are carried out, and it is verified that the method can detect the islanding for the parallel RLC loads even if the voltage frequency is within the non-detection zone. It is seen from the analysis of the detecting principle that there is no influence on the proposed method even if a large load connected in parallel frequently starts up or stops.

Molecular-Scale Electronics: From Concept to Function

Xiang, Dong,Wang, Xiaolong,Jia, Chuancheng,Lee, Takhee,Guo, Xuefeng American Chemical Society 2016 Chemical reviews Vol.116 No.7

<P>Creating functional electrical circuits using individual or ensemble molecules, often termed as 'molecular-scale electronics', not only meets the increasing technical demands of the miniaturization of traditional Si-based electronic devices, but also provides an ideal window of exploring the intrinsic properties of materials at the molecular level. This Review covers the major advances with the most general applicability and emphasizes new insights into the development of efficient platform methodologies for building reliable molecular electronic devices with desired functionalities through the combination of programmed bottom-up self-assembly and sophisticated top-down device fabrication. First, we summarize a number of different approaches of forming molecular-scale junctions and discuss various experimental techniques for examining these nanoscale circuits in details. We then give a full introduction of characterization techniques and theoretical simulations for molecular electronics. Third, we highlight the major contributions and new concepts of integrating molecular functionalities into electrical circuits. Finally, we provide a critical discussion of limitations and main challenges that still exist for the development of molecular electronics. These analyses should be valuable for deeply understanding charge transport through molecular junctions, the device fabrication process, and the roadmap for future practical molecular electronics.</P>