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.

Sequential Polyadenylation to Enable Alternative mRNA 3’ End Formation

Xiang-Dong Fu,Yajing Hao,Ting Cai,Chang Liu,Xuan Zhang 한국분자세포생물학회 2023 Molecules and cells Vol.46 No.1

In eukaryotic cells, a key RNA processing step to generate mature mRNA is the coupled reaction for cleavage and polyadenylation (CPA) at the 3′ end of individual transcripts. Many transcripts are alternatively polyadenylated (APA) to produce mRNAs with different 3′ ends that may either alter protein coding sequence (CDS-APA) or create different lengths of 3′UTR (tandem-APA). As the CPA reaction is intimately associated with transcriptional termination, it has been widely assumed that APA is regulated cotranscriptionally. Isoforms terminated at different regions may have distinct RNA stability under different conditions, thus altering the ratio of APA isoforms. Such differential impacts on different isoforms have been considered as post-transcriptional APA, but strictly speaking, this can only be considered “apparent” APA, as the choice is not made during the CPA reaction. Interestingly, a recent study reveals sequential APA as a new mechanism for post-transcriptional APA. This minireview will focus on this new mechanism to provide insights into various documented regulatory paradigms.

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>

The New Ecosystem of Cross-border E-Commerce among Korea, China and Japan Based on Blockchain

Xiang-Dong Shen,Xi Chen,Ran Ji,Ren-Hong Wu 한국무역학회 2020 Journal of Korea trade Vol.24 No.5

Purpose - The purpose of the study is to propose a theoretical framework of cross-border e-commerce ecosystems based on blockchain technology. The ecosystem includes five systems, namely, crossborder supply chain intelligent system, cross-border logistics system, cross-border payment system, cross-border product quality traceability system and cross-border customs supervision system. Design/methodology - This study firstly derived the main improvement factors for the new ecosystem based on blockchain through prior research and expert interviews on cross-border e-commerce. Then explored the use of virtue of decentralization, anti-counterfeiting traceability, consensus mechanism, smart contract and other means of the core technology of blockchain to overcome the bottleneck of cross-border e-commerce development among Korea, China, and Japan. Finally, proposed valuable implications in both theoretical and practical perspectives. Findings - As a result, we combined with the problems existing in cross-border e-commerce among Korea, China and Japan, this paper proposes a solution based on blockchain. On this basis, it constructs a cross-border e-commerce ecosystem among these three countries, including five systems. In addition, we discuss the main problems existing in the current blockchain, such as low transaction concurrency, security loopholes, and inconsistent standards, the corresponding countermeasures are proposed from the technical level, security level and industry standards. Originality/value - This study is the first to apply the blockchain technology to solve the cross-border e-commerce problems in Korea, China and Japan, which is of pioneering significance in both literature and practice. Block chain technology is in the ascendency. This study provides technical solutions for promoting the development of cross-border e-commerce import and export trade between Korea, China and Japan.

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>

IoT Makes Life Simpler: How to Improve the Chinese Consumer’s Intention to Use of LG HomNet Smart Home

Xiang-Dong Shen,Xi Chen,Yuting Jiang,Haixin Ji 한국무역학회 2022 Journal of Korea trade Vol.26 No.8

Purpose – The paper aims to develop the theory of TAM and perceived risk through a more comprehensive and rigorous understanding of the influencing factors of the consumer’s adoption of LG HomNet smart home from the perspective of trade-offs. Design/methodology – Based on the TAM and perceived risk theory, combined with the individual characteristics of consumers in the context of information technology as the external factors of the technology acceptance model, this paper constructs a theoretical model of the factors affecting the use intention of the consumer. It was empirically tested by using SEM, and survey data was collected from 458 respondents. Findings – The research results show that 9 hypotheses of the research model are supported and have reliable prediction accuracy. Consumers’ perceived interest, perceived connectivity and perceived controllability have a significant positive impact on their intention to use. In addition, this paper also confirmed the mediating effect of perceived usefulness and perceived ease of use. Originality/value – Consumers are very concerned about gains and losses. Low-level performance risks, security risks, and financial risks will drive the consumer to have a stronger intention to use, and financial risks have the strongest impact. This research provides a useful implication and guidance for smart home equipment manufacturers and service providers in product and service innovation and marketing and promotion strategies.

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.

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.

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>

Mineralization of calcium phosphate in reverse microemulsion

Xiang-Dong Kong,Xiao-Dan Sun,Jun-Biao Lu,Fu-Zhai Cui 한국물리학회 2005 Current Applied Physics Vol.5 No.5

In the present study, reverse microemulsion was prepared to regulate the mineralization of calcium phosphate. Calcium chlorideand sodium hydrogen phosphate aqueous solution were, respectively, dropped into the mixture of Span 80, Tween 80, andn-heptaneto get two kinds of emulsions.n-Buranol was used to adjust the emulsions to transparent state. Calcium phosphate was prepared byadding phosphate microemulsion to Calcium microemulsion. Heating method was used to induce the phase separation. After beingwashed with acetone and ethanol, the mineralized deposition were studied with scanning electron microscopy (SEM), X-ray dirac-tion (XRD) and transmission electron microscopy (TEM). The results indicated that the minerals in the deposition were mainlymonetite (DCPA) and the nanosized needle-like DCPA exhibited the preferential orientation along 200 direction..