Electrocatalytic oxygen reduction of three-dimensional carbon fiber-based composites for seawater oxygen-dissolved battery

Yu Juxin,Ma Li,Duan Tigang,Xin Yonglei,Lv Yanzhuo,Zhang Haibing 한국탄소학회 2022 Carbon Letters Vol.32 No.2

One-step hydrothermal reduction method was used to prepare three-dimensional carbon fiber brush-based graphene–platinum (CFB/Pt–G) composites to improve the electrocatalytic oxygen reduction activity of cathode materials for seawater oxygen-dissolved battery. Characterization results show that the reduced graphene oxide of as-prepared graphene–platinum composite displays the few-layer folded structure. In addition, Pt nanoparticles with the polycrystalline structure dispplay a preferential growth along the crystal plane of (111) and are mainly distributed around the defect cavities of folded graphene. Electrochemical results show that the diffusion-limited current density of CFB/Pt–G composite tested with 1600 rpm/min in 3.5% NaCl solution reaches 5 mA/cm2, while that of CFB/G is only 2.64 mA/cm2. Battery discharge results show that the maximum volume power density of CFB/Pt–G–Mg battery with a stable open voltage of 1.73 V is 81 times as much as the commercial seawater battery SWB1200.

Design of 1500V solar inverter stack beyond megawatt in NPC1 topology

Xin Hao,Kwok-Wai Ma,Jia Zhao,Xin-Yu Sun 전력전자학회 2017 전력전자학술대회 논문집 Vol.2017 No.7

This paper describes a design concept of NPC1 power stack for 1500VDC megawatt level solar inverter. This stack uses three latest half-bridge IGBT modules with highest power density and operation junction temperature, which enable realization of power level beyond 1MW without paralleling. Critical design concept on loop inductance is explained. Dynamic characteristics are verified by double-pulse test. Thermal characteristics and output power limits are verified by thermal test. Temperature-sensitive component on PCB as output power constraint is identified. Different PCB repositioning solutions are tested to give the overall output power thermal derating curves, which enable output power of 1.15MW at TA=55°C with 15°C thermal margin. The power stack characteristic and performance change under different thermal environment is further analyzed.

Brain Metabolic Network Redistribution in Patients with White Matter Hyperintensities on MRI Analyzed with an Individualized Index Derived from 18F-FDG-PET/MRI

Ma Jie,Hua Xu-Yun,Zheng Mou-Xiong,Wu Jia-Jia,Huo Bei-Bei,Xing Xiang-Xin,Gao Xin,Zhang Han,Xu Jian-Guang 대한영상의학회 2022 Korean Journal of Radiology Vol.23 No.10

Objective: Whether metabolic redistribution occurs in patients with white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) is unknown. This study aimed 1) to propose a measure of the brain metabolic network for an individual patient and preliminarily apply it to identify impaired metabolic networks in patients with WMHs, and 2) to explore the clinical and imaging features of metabolic redistribution in patients with WMHs. Materials and Methods: This study included 50 patients with WMHs and 70 healthy controls (HCs) who underwent 18F-fluorodeoxyglucose-positron emission tomography/MRI. Various global property parameters according to graph theory and an individual parameter of brain metabolic network called “individual contribution index” were obtained. Parameter values were compared between the WMH and HC groups. The performance of the parameters in discriminating between the two groups was assessed using the area under the receiver operating characteristic curve (AUC). The correlation between the individual contribution index and Fazekas score was assessed, and the interaction between age and individual contribution index was determined. A generalized linear model was fitted with the individual contribution index as the dependent variable and the mean standardized uptake value (SUVmean) of nodes in the whole-brain network or seven classic functional networks as independent variables to determine their association. Results: The means ± standard deviations of the individual contribution index were (0.697 ± 10.9) x 10-3 and (0.0967 ± 0.0545) x 10-3 in the WMH and HC groups, respectively (p < 0.001). The AUC of the individual contribution index was 0.864 (95% confidence interval, 0.785–0.943). A positive correlation was identified between the individual contribution index and the Fazekas scores in patients with WMHs (r = 0.57, p < 0.001). Age and individual contribution index demonstrated a significant interaction effect on the Fazekas score. A significant direct association was observed between the individual contribution index and the SUVmean of the limbic network (p < 0.001). Conclusion: The individual contribution index may demonstrate the redistribution of the brain metabolic network in patients with WMHs.

Abundant Manganese Complex-Anchored BiOI Hybrid Photocatalyst for Visible Light-Driven CO2 Reduction

Xin Xin,Ning Ma,Changying Hu,Qi Liang,Zhaoyong Bian 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.2

An abundant manganese complex-anchored BiOI hybrid system for CO2 photocatalytic conversion was constructed. Layered BiOI and tricarbonyl Mn bipyridyl complex with carboxyl acid groups were connected with covalent bonds and used as visible light antenna and CO2 reduction reaction centers, respectively. The covalent connection of this hybrid system benefits the transfer of electrons from the semiconductor to the Mn complex. The anchoring group (carboxyl) is the key to CO2 reduction for the direct coupling of the two units, facilitating the transfer of electrons from BiOI to the manganese complexes. The photocatalytic properties and stability of the tri-carbonyl Mn–bipyridyl complex were significantly enhanced with the aid of anchored BiOI. A high turnover number (TON = 74) of HCOO- formation from CO2 could be achieved using this hybrid system under visible light irradiation.

한국어 부사 ‘작작’의 의미와 분포

( Ma Xin ),김정남 ( Kim Jungnam ) 한국외국어대학교 언어연구소 2020 언어와 언어학 Vol.0 No.87

This study is about the etymological meaning of jagjag and its characteristics of pragmatics through actual examples from the corpus. Adverb jagjag in modern Korean originated from jyagjyag of the 15th century. It is formed by the duplication of the stem jag- of the adjective jagda. Hence, the meaning of jagjag was interpreted literally until the 19th century where jagjag was a kind of modal adverb. However, since the period of modern Korean, jagjag has become a kind of prohibitive adverb and has functioned as a negative command. In this article, we revealed that jagjag co-occurs with negative-meaning verbs or where at least the object or modifier of those verbs have negative meanings, through actual and specific examples from the corpora. We analyzed the mood of co-occurring verbs and their final endings. We found that most of the mood is plain speech-level, and most final endings are imperative. Ironically, the honorific endings strengthen threatening of the listeners’ face, and the adverbs jom, jebal, and jebal jom help reduce the feature of FTA (Face Threatening Act) in a jagjag structure.

Effect of Externality in Multiplex Networks on One-layer Synchronization

Xin Jiang,Meng Li,Zhiming Zheng,Yifang Ma,Lili Ma 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.11

Synchronization phenomenon plays an important role in the dynamic process on complex networks. In this letter, we consider synchronization under multiplex structures and explore the effect of external parts on the multilayered Kuramoto model with positive correlation between frequencies and degree. We show that large and strong mixing parts of the external layer may put off synchronization while the coupling strength of external layers has an accelerating, but limited, influence on synchronization. In particular, an explosive synchronization can be obtained by weakening the co-evolution coupling strength. The transition tends to be smooth when the co-evolution coupling strength increases. Our findings indicate that externality from multiplex networks, especially the mixing parts, and the co-evolution coupling strength should be of importance for synchronization on one certain layer.

도금폐수처리공정의 처리효율 개선방안

마심초(Xin Chao Ma),임봉수(Bong Su Lim),최찬수(Chan Soo Choi) 대전대학교 환경문제연구소 2016 환경문제연구소 논문집 Vol.20 No.-

This study was performed to evaluate the alternative improvement plans for removal efficiency of plating wastewater treatment processes with high concentrations of heavy metals and total nitrogen in the influent. The average removal efficiency rates of the existing wastewater treatment plant were 58% of CODcr, 74% of CODmn, 78% of TN, 99% of TP, respectively. However, the concentration of SS (about 250 mg/L) was over the emission standard (120 mg/L). TN and Cu²+ concentrations were over the emission standard; about 62 mg/L and 5.2 mg/L, respectively. Carbon source quantity, fed into the anoxic tank of the biological wastewater treatment process, was controled by calculating the optimum required COD amount for denitrification. The removal efficiency rates of Zn²+, Cu²+, and Ni²+ were achieved using an electrolysis reactor 89%, 89%, and 99%, respectively. Therefore, it was recommended to modify the existing wastewater treatment process including the chemical precipitation to the electrolysis reactor as an efficient and environmentally effective alternative.

Ontology-Based Exchange of Product Data Semantics between CAD and CAE

Qinyi Ma,Yajun Wang,Yan Lv,Xin Jin,Maojun Zhou 보안공학연구지원센터 2014 International Journal of Multimedia and Ubiquitous Vol.9 No.12

The interoperation of various applications will need a representation that goes beyond the traditional geometry-based one, which is inadequate for capturing semantic information. This paper proposes an approach to annotate the CAD models based on ontology with the aim of making the design intent understood by computer and applied in engineering analysis, such as FEA. The paper presents the design domain ontology and FEA domain ontology, and applies feature technologies and the semantic Web to complete annotation. Semantic markup can embed the engineering semantic information such as product function, and design principle into the CAD geometry data through annotating, it makes the analyzers reuse design ideas quickly and conveniently to increase efficiency. The semantic file is proposed to support an exchange of product data semantics between CAD and CAE. The main idea of the approach is presented and key technologies are elaborated, including the creation of the FEA solution template, and the matching algorithm between semantic markup file and FEA template file. Finally, the feasibility and effectiveness of the approach is empirically validated by a case study.

중국 파양호(鄱阳湖) 유역 수질환경오염 문제와 개선 전략

마심초(Xin Chao Ma),임봉수(Bong Su Lim),경해룡(Hai Long Jing) 대전대학교 환경문제연구소 2015 환경문제연구소 논문집 Vol.19 No.-

대청호 추동취수탑 부근의 수질변화 특성

마심초 ( Xin Chao Ma ),임봉수 ( Bong Su Lim ),허순욱 ( Soon Uk Heo ),곽미애 ( Mi Ae Kwak ) 한국물환경학회 2015 한국물환경학회지 Vol.31 No.6

This study has been carried out to provide the basic data obtained from the evaluation of the variation of water quality around the Chudong intake tower in Daechung resevoir, which may be able to help the establishment of a pure water supply policy. Five sites around the Chudong intake tower were selected, and the average data for recent ten years(from year 2004 to year 2013) were analysed. The average water quality around Chudong intake tower are as followed; pH 7.5, DO 8.7 mg/L, BOD 1.0 mg/L, COD 3.0 mg/L, SS 3.0 mg/L, TN 1.495 mg/L, TP 0.017 mg/L, and Chlorophyll-a 6.5 mg/m3 were matched the good class by comparing with the living environment standard of reservoir. COD values of higher than 3.0 mg/L after July were likely due to non-point pollutants and algae outbreak during rainy summer season. Total phosphorus rose sharply in the summer season, and then algae watch was issued consistently for average 40 days. Total nitrogen to total phosphorus ratio was average 90, and it is important to control the inflow phosphrous from small stream for proper management to block an algae growth according to eutrophication. It was recommended to operate the algae removing boats around intake tower from July to October, and was required advanced water treatment processes to remove NBD COD and bad odor and taste due to algae growth.