홍콩주식시장 투자자구성 변화에 대한 정부규제의 효과

강주화,이창범,윤성민 釜山 大學校 經營 經濟 硏究所 2009 經營 經濟 硏究 Vol.28 No.2

인휠구동 전기차의 차량운동제어를 위한 기준모델적응제어

조일범(Yi-Fan Zhao),이창노(Chang-Ro Lee),김영렬(Young-Ryul Kim) 한국산학기술학회 2021 한국산학기술학회논문지 Vol.22 No.10

최근 전기차는 인휠모터에 의해 각 바퀴를 독립적으로 구동함으로서 차량제어성능을 대폭 향상키고 있다. 차량운동제어의 관점에서 보면 전기차는 전기모터의 빠른 응답성과 제어의 용이성으로 인해 차량의 운동성능을 대폭 향상시킬 수 있는 잠재력이 있다. 특히 최근에 도입된 인휠모터 구동은 각 바퀴를 독립적으로 구동할 수 있으므로 차량운동제어에 필요한 능동요모멘트를 내기 위하여 모터제어로 구동바퀴의 휠토크를 증감할 수 있으므로 제어의 폭이 넓다. 다양한 차량운동제어기술 중에서도 차량의 파라미터나 주행환경 변화에도 강인성과 안정성을 확보하는 적응제어기의 적용사례가 많다. 적응이란 새로운 환경에 순응하도록 거동을 변화시키는 것이므로 적응제어기는 차량의 동역학이나 외란의 변화에 대하여 응답을 수정할 수 있는 제어기이다. 본 논문에서는 인휠모터로 구동하는 전기차의 차량운동제어 (VDC)를 위하여 기준모델적응제어 (MRAC)를 적용하였다. 이를 위해 운전자의 조향입력에 대하여 원하는 차량응답을 갖는 1차계로 기준모델을 정의하였으며 적응기재로 Lyapunov 함수를 사용하여 제어기를 설계하였다. 제안된 제어기의 차량제어성능을 검증하기 위해 타이어-노면 마찰계수의 변동에 대한 J-Turn, Sine Steer, 이중차선변경에 대한 차량주행 시뮬레이션을 수행하였다. Recently, electric vehicles have been significantly improving vehicle control performance by independently driving each wheel by an in-wheel motor. This is because the in-wheel motor has a faster response and a wider range of control compared to an existing mechanical drivetrain. Vehicles usually accompany changes in vehicle parameters, and an adaptive controller that adjusts control parameters is effective to secure control robustness. In this study, reference model adaptive control (MRAC) was applied for vehicle dynamics control (VDC) of an electric vehicle driven by in-wheel motors. To this end, the desired vehicle response to a driver"s steering input was defined as a reference model, and a controller was designed using a Lyapunov function as an adaptation mechanism. In order to verify the performance of the proposed controller, vehicle driving simulations for a J-turn, sine steering, and double lane change were performed with changes of the friction coefficient between the tires and road.

Experimental Study on the Corrosion of Buried Pipeline in Coastal Area Under the Interference of Stray Current

Fan Xu,Huijun Wu,Xin Hu,Zhong-Chang Wang 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.5

To explore the eff ect of stray current and the concentration of Cl − on corrosion of buried pipeline in coastal area, in this paper, indoor electrochemical experiments were used to change the voltage of AC interference. The electrochemical parameters such as zero current potential error, Tafel constant and corrosion current density error of the polarization curves obtained in three diff erent concentrations of Cl − solutions without alternating current interference and with diff erent intensities of alternating current interference were compared and measured. The results showed that the corrosion potential of the sample was shifted negatively. When the interference ratio of the fi xed voltage was not disturbed, the corrosion current increased, and the corrosion process changed from cathode reaction control to hybrid control. AC stray current could aggravate the corrosion process of Q235 steel. In the presence of AC stray current, with the increase of applied AC voltage, the corrosion potential of Q235 steel moved negatively, the corrosion current density increased and the corrosion rate accelerated. The concentration of Cl − had a great infl uence on the reaction rate, and the higher the voltage, the more obvious the eff ect. This is of great signifi cance for eff ectively predicting the life of buried pipelines, improving the reliability of buried pipelines during service and protecting the safety of existing pipeline facilities.

A template-hatched method towards poly(acrylic acid) hydrogel spheres with ultrahigh ion exchange capacity and robust adsorption of environmental toxins

Fan Yang,Xin Fan,Man Zhang,Chen Wang,Wei-Feng Zhao,Chang-Sheng Zhao 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

Polyacrylic acid/polyethersulfone (PAA/PES) capsules were adopted as templates to synthesize PAA/PES core–shell spheres, and the PES shell of spheres could be removed automatically by the swelling nature of the cross-linked PAA hydrogel core. By using the method, PAA hydrogel spheres were prepared with an ultrahigh ion exchange capacity of 12 meq g−1, and the spheres showed a high adsorption capacity for methylene blue. The PAA-polyacrylamide hydrogel spheres with dual adsorption ability and good mechanical property were also prepared. It was revealed that these two hydrogel spheres can be effectively utilized in the removal of environmental toxins.

RIGID-PLASTIC SEISMIC DESIGN OF REINFORCED CONCRETE SHEAR WALL

CHANG LIN FAN,SHAN YUAN ZHANG,SUNGHO PARK 한국소성가공학회 2008 한국소성가공학회 컨퍼런스 Vol.2008 No.10

Structure and Performances of xLiFePO4/C·(1 − x)Li3V2(PO4)3/C Cathode for Lithium-Ion Batteries by Using Poly(vinyl alcohol) as Carbon Source

Chang-ling Fan,Wei-hua Zhang,Tao-tao Zeng,Ling-fang Li,Xiang Zhang,Shao-chang Han 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.11

Poly(vinyl alcohol), whose pyrolysis carbon possesses high conductivity of 8.88 × 10−1 S/cm, was used to synthesize xLiFePO4/C·(1 − x)Li3V2(PO4)3/C cathode. It was characterized by X-ray diffraction, scanning electron microscopy, conductivity, cyclic voltammetry, and galvanostatic charge and discharge experiments. Results show that LiFePO4/C and Li3V2(PO4)3/C coexists in the cathode. The particles sizes of 0.75LiFePO4/C·0.25Li3V2(PO4)3/C (x = 0.75) are much smaller than 100 nm due to the role of poly(vinyl alcohol). Its conductivity is 8.79 × 10−2 S/cm. The oxidative and reductive peaks in cyclic voltammetry are sharp and symmetrical. Their low potential gaps indicate that the extractions and insertions of lithium ion possess excellent reversibility. Its discharge capacities at 1 and 5 C are 141.1 and 100.1 mAh/g. The more Li3V2(PO4)3/C in cathode results in the deterioration of electrochemical performances due to its low theoretical capacity. It is concluded that poly(vinyl alcohol) is an effective carbon source in the preparation of xLiFePO4/C·(1 − x)Li3V2(PO4)3/C composite cathode with excellent performances.

Responses of Soil Rare and Abundant Sub- Communities and Physicochemical Properties after Application of Different Chinese Herb Residue Soil Amendments

( Fan Chang ),( Fengan Jia ),( Min Guan ),( Qingan Jia ),( Yan Sun ),( Zhi Li ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.5

Microbial diversity in the soil is responsive to changes in soil composition. However, the impact of soil amendments on the diversity and structure of rare and abundant sub-communities in agricultural systems is poorly understood. We investigated the effects of different Chinese herb residue (CHR) soil amendments and cropping systems on bacterial rare and abundant subcommunities. Our results showed that the bacterial diversity and structure of these subcommunities in soil had a specific distribution under the application of different soil amendments. The CHR soil amendments with high nitrogen and organic matter additives significantly increased the relative abundance and stability of rare taxa, which increased the structural and functional redundancy of soil bacterial communities. Rare and abundant sub-communities also showed different preferences in terms of bacterial community composition, as the former was enriched with Bacteroidetes while the latter had more Alphaproteobacteria and Betaproteobacteria. All applications of soil amendments significantly improved soil quality of newly created farmlands in whole maize cropping system. Rare sub-communitiy genera Niastella and Ohtaekwangia were enriched during the maize cropping process, and Nitrososphaera was enriched under the application of simple amendment group soil. Thus, Chinese medicine residue soil amendments with appropriate additives could affect soil rare and abundant sub-communities and enhance physicochemical properties. These findings suggest that applying soil composite amendments based on CHR in the field could improve soil microbial diversity, microbial redundancy, and soil fertility for sustainable agriculture on the Loess Plateau.

Three-dimensional finite element analysis on the effects of maxillary protraction with an individual titanium plate at multiple directions and locations

Fan Wang,Qiao Chang,Shuran Liang,Yuxing Bai 대한치과교정학회 2024 대한치과교정학회지 Vol.54 No.2

Objective: A three-dimensional-printed individual titanium plate was applied for maxillary protraction to eliminate side effects and obtain the maximum skeletal effect. This study aimed to explore the stress distribution characteristics of sutures during maxillary protraction using individual titanium plates in various directions and locations. Methods: A protraction force of 500 g per side was applied at forward and downward angles between 0° and 60° with respect to the Frankfort horizontal plane, after which the titanium plate was moved 2 and 4 mm upward and downward, respectively. Changes in sutures with multiple protraction directions and various miniplate heights were quantified to analyze their impact on the maxillofacial bone. Results: Protraction angle of 0–30° with respect to the Frankfort horizontal plane exhibited a tendency for counterclockwise rotation in the maxilla. At a 40° protraction angle, translational motion was observed in the maxilla, whereas protraction angles of 50–60° tended to induce clockwise rotation in the maxilla. Enhanced protraction efficiency at the lower edge of the pyriform aperture was associated with increased height of individual titanium plates. Conclusions: Various protraction directions are suitable for patients with different types of vertical bone surfaces. Furthermore, when the titanium plate was positioned lower, the protraction force exhibited an increase.

Effects of American Ginseng Cultivation on Bacterial Community Structure and Responses of Soil Nutrients in Different Ecological Niches

( Fan Chang ),( Fengan Jia ),( Rui Lv ),( Min Guan ),( Qingan Jia ),( Yan Sun ),( Zhi Li ) 한국미생물생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.4

American ginseng (Panax quinquefolium L.) is a perennial herbaceous plant widely cultivated in China, Korea, the United States, and Japan due to its multifunctional properties. In northwest China, transplanting after 2-3 years has become the main mode of artificial cultivation of American ginseng. However, the effects of the cultivation process on the chemical properties of the soil and bacterial community remain poorly understood. Hence, in the present study, high-throughput sequencing and soil chemical analyses were applied to investigate the differences between bacterial communities and nutrition driver factors in the soil during the cultivation of American ginseng. The responses of soil nutrition in different ecological niches were also determined with the results indicating that the cultivation of American ginseng significantly increased the soluble nutrients in the soil. Moreover, the bacterial diversity fluctuated with cultivation years, and 4-year-old ginseng roots had low bacterial diversity and evenness. In the first two years of cultivation, the bacterial community was more sensitive to soil nutrition compared to the last two years. Proteobacteria, Actinobacteria, Gemmatimonadetes, Acidobacteria, Firmicutes, and Bacteroidetes dominated the bacterial community regardless of the cultivation year and ecological niche. With the increase of cultivation years, the assembly of bacterial communities changed from stochastic to deterministic processes. The high abundance of Sphingobium, Novosphingobium, and Rhizorhabdus enriched in 4-years-old ginseng roots was mainly associated with variations in the available potassium (AK), total phosphorus (TP), total potassium (TK), and organic matter (OM).

Impact of Refined Land Surface Properties on the Simulation of a Heavy Convective Rainfall Process in the Pearl River Delta Region, China

Ming Chang,Shaofen Fan,Qi Fan,Weihua Chen,Yiqiang Zhang,Yu Wang,Xuemei Wang 한국기상학회 2014 Asia-Pacific Journal of Atmospheric Sciences Vol.50 No.5

The location and occurrence time of convective rainfallshave attracted great public concern as they can lead to terribledisasters. However, the simulation results of convective rainfalls inthe Pearl River Delta region often show significant discrepanciesfrom the observations. One of the major causes lies in the inaccurategeographic distribution of land surface properties used in the modelsimulation of the heavy precipitation. In this study, we replaced thedefault soil and vegetation datasets of Weather Research andForecasting (WRF) model with two refined datasets, i.e. theGlobCover 2009 (GLC2009) land cover map and the HarmonizedWorld Soil Database (HWSD) soil texture, to investigate the impactof vegetation and soil on the rainfall patterns. The result showed thatthe simulation patterns of convective rainfalls obtained from thecoupled refined datasets are more consistent with the observationsthan those obtained from the default ones. By using the coupledrefined land surface datasets, the overlap ratio of high precipitationdistricts reached 36.3% with a variance of 28.5 km from theobserved maximum rainfall position, while those of the defaultUnited States Geological Survey (USGS) dataset and ModerateResolution Imaging Spectroradiometer (MODIS) dataset are 17.0%/32.8 km and 24.9%/49.0 km, respectively. The simulated totalrainfall amount and occurrence time using the coupled refineddatasets are the closest to the observed peak values. In addition, theHWSD soil data has improved the accuracy of the simulatedprecipitation amount, and the GLC2009 land cover data also didbetter in catching the early peak time.