Development of Fiber Optic FBG Inclinometer for Stability Monitoring of Soil Slope

Guohua Jin,Il-Bum Kwon(권일범),Geun-Jin Kim(김근진),Dae-Cheol Seo(서대철) 대한토목학회 2009 대한토목학회 학술대회 Vol.2009 No.10

Valley V² Control Technique for Switching Converters with Fast Transient Response

Guohua Zhou,Jianping Xu,Jin Sha,Yanyan Jin 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5

Valley V² control technique for switching converters is proposed in this paper. By utilizing output voltage ripple as pulse-width modulation ramp and valley voltage of output voltage ripple as additional control variable, valley V² control technique provides faster load transient response than conventional current-mode control techniques. Steady-state and transient performances of switching converters with valley V² control, peak V² control, and current-mode control are compared and verified by experimental results.

Compressive-Tensile Mechanics and Energy Consumptions of a Cementitious Composite with High Utilization of Steel Slag

Guohua Sheng,Shengji Jin,Chao Li,Quan Bai,Xiaoyu Wang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.3

In response to the National Development and Reform Commission's “Guiding Opinions on Comprehensive Utilization of Large Solid Wastes during the Fourteenth Five Year Plan”, further expand the use of steel slag as concrete admixture in construction projects and other fields, and gradually improve the comprehensive utilization ratio, a cementitious composite with high utilization of steel slag (CHS) was developed, which is with the cement replaced by high-content super-fine steel slag powder (SSP) (replacement ratio υ ≥ 30%) as the cementitious materials, steel slag sand (SS) as the only aggregate and environmentally basalt fiber (BF) for toughening. It improves the utilization percentage of steel slag (SSP and SS) and reduces the consumption of natural resources such as cement and natural sand. Use BF to achieve better strength and toughness. In order to better understand the performance of CHS and make it better used in the engineering field. Study the influence of each component on the strength and energy consumption of compression and splitting tension, and strive to find the optimal proportion and lay the theoretical foundation for its application. Through the tests, the effects of high replacement ratio υ (30% − 50%), low binder-aggregate ratio γ (0.31 − 0.44), and BF content ρv (0% − 2%) on the aspects of peak strength, force-deformation curve and energy consumption were analyzed. The results show that the standard curing fck and ft,s can reach 40 MPa and 5 MPa respectively. With the increase of υ, the maximum axial compressive strength fck and splitting tensile strength ft,s decreased insignificantly. The γ has an important influence on fck and ft,s. When it increases from 0.31 to 0.44, fck increases linearly by 63.1% to 40.4 MPa, while ft,s increases by 52.8% to 5.18 MPa. As ρv increases, fck and ft,s show a trend of first increasing and then decreasing. ρv exerts a significant impact on the descending segments of stress-strain response curves of the compression which expressed as bilinear and trilinear models with different ρv after normalization. The energy consumptions of peak, total, and residual (Epeak, Edisp, Eres) show a slight downward trend with the increase of υ, a significantly upward trend with the increase of γ. With the increase of γv, Epeak and Edisp increase first and then tend to be flat, while Eres always increases and the percentages of Eres/Edisp in the compressive test increase from 22.6% to 38.5%, reflecting the improvement of the compressivetoughness of BF.

A Quantitative Method for Seismic Robustness of RC Frame Considering Resistance Vulnerability of Column and Storey Drift Ratios

Guohua Sheng,Shengji Jin,Lintao Ma,Quan Bai,Chao Xu,Xiaoyu Wang 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.1

The concept of seismic robustness is proposed by combining the concept of seismic performance and structural robustness. The existing qualitative, quantitative and evaluation methods of seismic robustness are all direct researched on the whole structure, and the influence mechanism of its internal components on the overall seismic robustness is still unclear. It is very important to establish a clear relationship between component design and structural seismic robustness for the structural design, reinforcement design and final evaluation of structural seismic robustness. Based on this, taking the column as the starting point, a quantitative method for the seismic robustness of RC frame by the seismic robustness index is proposed, which takes into account the resistance vulnerability of column and influence of column on the storey drift ratios (SDRs). In which, the resistance vulnerability is represented by the defined control vulnerability coefficient Pimax, and the influence on the SDRs are represented by the storey drift ratio importance coefficients (SDRCs) . The method not only reflects the essential mechanical properties of the column, but also reflects the effects brought about by different SALs. The feasibility of the method is demonstrated by numerical examples of two types of failures (assuming single column and two columns failure), and four optimization design proposals are proposed for it. The analysis shows that  of the target columns to the floor where the target columns located are obviously greater than those on the remaining floors of the target frame. The seismic robustness index R decreases sharply with the increase of the seismic action level (SAL). R is different compare single column failure with two columns failure under 4 SALs. The most effective way to improve the R of the frame under a certain SAL is to retrofit its control column.

Analysis and Design of Seismic Robustness of FRP-Reinforced Frame based on Interlayer Displacement

Guohua Sheng,Quan Bai,Shengji Jin,He Yu,Mingfei Li 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.6

For a structure, robustness is a high-level performance index since it takes account of the effects of impact, explosion, earthquake and other instantaneous dynamic actions on the structure safety. In this work, layer is taken as the tie between the column and the frame. Two concepts, namely, “layer importance coefficient” of the column and “layer vulnerability coefficient” of the frame, are introduced. Based on these, the method for calculating the seismic robustness is proposed and analyzes the seismic robustness of three FRP-reinforced frame models. The results show that: The robustness of the frame with the 1st layer column reinforced with two layer CFRP (carbon fiber reinforced polymer) (F20RC) and the 1st and 2nd layer column reinforced with one layer CFRP (F11RC), respectively are better than that of the 1st layer column reinforced with one layer CFRP (F10RC). As the intensity of earthquake action increases, the seismic robustness index decreases. When UBC97's acceleration-related parameter Ca = 0.36 and velocityrelated parameter Cv = 0.36, the robustness coefficient of the three models F20RC, F11RC, F10RC are 36.5, 37.2, 34.1, respectively. When Ca = 0.6, Cv = 0.6, that of F20RC, F11RC, F10RC are 24.2, 20.4, 19.5, respectively. Finally, the procedure for designing the FRP-reinforced frame based on the seismic robustness is presented and demonstrated.

실내 공기질 모니터링 및 분석을 위한 통합 시스템 개발

리국화(Guohua Li),김동길(Tongji Jin),변영화(Yinghua Bian),서영욱(Rongxu Xu),임상범(Sang Boem Lim) 대한공간정보학회 2015 한국지형공간정보학회 학술대회 Vol.2015 No.5

Synthesis and characterization of a K/K2CO3-based solid superbase as a catalyst in propylene dimerization

Haibo Jin,Heng Jiang,Qiwei Wang,Suohe Yang,Guohua Luo,Guangxiang He 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.2

A novel solid superbase 3%K/K2CO3 was prepared by loading metallic potassium on K2CO3. The optimized preparation conditions included a loading time of 1.5 h, loading temperature of 150 oC, loading amount of 3wt% and average carrier size of 120 μm. Under the optimum conditions, the conversion of propylene is about 60% with the selectivity of dimers 98.5% and the selectivity of 4MP1 86.3%. In addition, the superbase 3%K/K2CO3 has a base strength of H−≥37, and the concentration of basic sites of H−≥35 is approximately 0.3mmol·g−1 CAT. The microcrystal of metallic potassium was determined using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It was assumed that the oxygen species, which are adjacent to lattice defects, such as the crystalline corners, edges and vacancies of metallic potassium microcrystals, constituted the superbasic sites.

Numeral Description of Grain Size Effects of Tin Oxide Gas-Sensitive Elements and Evaluation of Depletion Layer Width

Jianqiao Liu,Guohua Jin,Zhaoxia Zhai,Faheema Fairuj Monica,Xuesong Liu 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.3

The grain size effects on tin oxide gas-sensitive elements are numerically described by the model of gradient-distributed oxygen vacancies, which extends the receptor function of semiconductors to the condition of inhomogeneous donor density in grains. The sensor resistance and the response to the reducing gas are formulated as functions of the grain size and the depletion layer width. The simulations show good agreement with the experimental results. The depletion layer width is estimated as 4 nm for the undoped SnO2 element, whereas the values are 2 and 7 nm for Sb-doped and Al-doped samples, respectively. The results are experimentally verified by the donor-doped SnO2 thin films, the depletion layer widths of which are evaluated on the basis of the correlation between the electrical resistance and the Sb-doping amount. The location of the Fermi level is found to be a crucial factor that dominates the evaluation results.

복합적 재난재해 대응체계에 필요한 자동화 시나리오 개발

김신화(Xinhua Jin),리국화(Guohua Li),서영욱(Rongxu Xu),임상범(Sang Boem Lim) 대한공간정보학회 2016 한국지형공간정보학회 학술대회 Vol.2016 No.05

Simulation of the Grain Size Effect in Gas-Sensitive SnO2 Thin Films Using the Oxygen Vacancy Gradient Distribution Model

Jianqiao Liu,Zhaoxia Zhai,Guohua Jin,Yuan Li,Faheema Fairuj Monica,Xuesong Liu 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.1

The model of gradient-distributed oxygen vacancies is utilized in simulatingthe grain size effects of gas-sensitive SnO2 thin films. The distribution profileof oxygen vacancies has a grain size effect and the profile gradient correlatespositively with the radius of the grains. The simulation results show that thegrain size is a fundamental factor dominating the gas-sensing properties ofthin films. The potential barrier height and resistivity have significant grainsize effects when m is between 0.1 and 0.5 nm−1. The size effects on sensorresponse to stimulant gases can be enhanced by increasing the value of m orthe absolute value of α. Two expressions are used to simulate the grain sizeeffect of the sensor response. The expressions act similarly when α < 0.2. The simplified response provides a neat function to quantitatively explain thesensor performance on gases with low partial pressure. Although the accurate response is complicated, it is applicable to theentire concentration range. A small power-law exponent n is calculated from the accurate response expression when a high gasconcentration is employed, illustrating a “saturation effect” of the response.