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A Resistance Deviation-To-Time Interval Converter Based On Dual-Slope Integration
Zhi-Heng Shang,정원섭,손상희 한국전기전자학회 2015 전기전자학회논문지 Vol.19 No.4
A resistance deviation-to-time interval converter based on dual-slope integration using second generation current conveyors (CCIIs) is designed for connecting resistive bridge sensors with a digital system. It consists of a differential integrator using CCIIs, a voltage comparator, and a digital control logic for controlling four analog switches. Experimental results exhibit that a conversion sensitivity amounts to 15.56 μs/Ω over the resistance deviation range of 0-200 Ω and its linearity error is less than 0.02%. Its temperature stability is less than 220 ppm/℃ in the temperature range of -25-85℃. Power dissipation of the converter is 60.2 mW.
A Resistance Deviation-To-Time Interval Converter Based On Dual-Slope Integration
Shang, Zhi-Heng,Chung, Won-Sup,Son, Sang-Hee Institute of Korean Electrical and Electronics Eng 2015 전기전자학회논문지 Vol.19 No.4
A resistance deviation-to-time interval converter based on dual-slope integration using second generation current conveyors (CCIIs) is designed for connecting resistive bridge sensors with a digital system. It consists of a differential integrator using CCIIs, a voltage comparator, and a digital control logic for controlling four analog switches. Experimental results exhibit that a conversion sensitivity amounts to $15.56{\mu}s/{\Omega}$ over the resistance deviation range of $0-200{\Omega}$ and its linearity error is less than ${\pm}0.02%$. Its temperature stability is less than $220ppm/^{\circ}C$ in the temperature range of $-25-85^{\circ}C$. Power dissipation of the converter is 60.2 mW.
N₂/O₂ 혼합가스중에서 전극형상 및 Teflon 수지 크기변화에 따른 연면절연파괴특성
양지항(Zhi-Heng Yang),박광서(Kwang-seo Park),최영길(Young-Kil Choi),박원주(Won-Zoo Park),이광식(Kwang-Sik Lee) 한국조명·전기설비학회 2010 한국조명·전기설비학회 학술대회논문집 Vol.2010 No.9월
In this paper, proposed a basic data of the surface insulation breakdown characteristics in N₂/O₂ mixture gas with electrode shape and Teflon resin size. The used of the electrodes are sphere electrode to plane electrode and needle electrode to plane electrode in this experiment. The solid insulators are Teflon resin with the diameter by 70mm, 100mm, respectively. Used N₂/O₂ mixture rates of the Gas by 80%:20% in 1~6 pressure, Under the same conditions we can obtain different surface Insulation breakdown voltage.
Two New Species in the Family Cunninghamellaceae from China
( Heng Zhao ),( Jing Zhu ),( Tong-kai Zong ),( Xiao-ling Liu ),( Li-ying Ren ),( Qing Lin ),( Min Qiao ),( Yong Nie ),( Zhi-dong Zhang ),( Xiao-yong Liu ) 한국균학회 2021 Mycobiology Vol.49 No.2
The species within the family Cunninghamellaceae are widely distributed and produce important metabolites. Morphological studies along with a molecular phylogeny based on the internal transcribed spacer (ITS) and large subunit (LSU) of ribosomal DNA revealed two new species in this family from soils in China, that is, Absidia ovalispora sp. nov. and Cunninghamella globospora sp. nov. The former is phylogenetically closely related to Absidia koreana, but morphologically differs in sporangiospores, sporangia, sporangiophores, columellae, collars, and rhizoids. The latter is phylogenetically closely related to Cunninghamella intermedia, but morphologically differs in sporangiola and colonies. They were described and illustrated.
Dynamic behavior analysis of push-the-bit rotary steerable bottom hole assembly
Zhi-chuan Guan,Heng Wang,Yu-cai Shi,Wei-qing Chen,Guo-shan Zhao,Jian-yun Wang,Guang-qiang Cao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.4
Rotary steerable drilling technology is currently an advanced technology in the field of drilling engineering. A good understanding of dynamic behavior of rotary steerable system will benefit the drilling progress. Aimed at push-the-bit type of rotary steerable tool, finite element method was employed to model the rotary steerable bottom hole assembly (RSBHA) and establish the motion equation. Contact interaction between drill string and wellbore wall was analyzed and taken as the constraint condition in solving RSBHA motion equation. Force applied by steering pads was as the external force acting at the pads node. Then RSBHA motion state and bit lateral force were obtained by using Newmark method to solve the motion equation. A case was given and effects of influencing factors were analyzed. The results show that stick-slip phenomenon occurs under 60 r/min rotary speed condition and disappears when rotary speed rises to 90 r/min. Fully developed backward whirl comes into being at the near-bit stabilizer when rotary speed increases to 120 r/min. High weight on bit intensifies bit torsional vibration while larger pads’ steering force decreases the bit torsional vibration. Upper stabilizer plays a part in weakening RSBHA backward whirl under high rotary speed condition but reduces the inclination force. Time average of bit lateral force is mainly determined by pads’ steering force. Based on the results, corresponding suggestions were proposed to make the RSBHA be better used in the field applications.
Chaoyang Heng,Song Sun,Jiantao Zhang,Zhi Zhou 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.1
The ultra-shallow buried excavation technology, utilizing pipe-roof steel arches as main supporting structure, has broad application prospects. Current mainstream pipe-roof design schemes often adopt simple beam theory or engineering analogy methods, which do not take into account the cumulative deformation and have high engineering disaster risk. Based on the beam Winkler model of elastic foundation, this paper studies the method on interactive effects among pipe-roof, steel bracing and foundation soil. The calculation model of the ultra-shallow buried pipe-roof and steel bracing is established with theoretical derivation. And a new supporting design method of ultra-shallow buried excavation under interactive effects is proposed. Firstly, an optimal method for determining the elasticity coefficient of steel arch and foundation soil is put forward on interactive effects among pipe-roof, steel bracing and foundation. Secondly, considering the enhancement effect of concrete wall, a procedure of determining the elasticity coefficient of fulcrum is described. That is, the first steel arch, which is adjacent to underground passage tunnel face, returns to the 1.5H (H is the height of the hole) range as an enhanced transition section, and the elasticity coefficient of fulcrum varies linearly with its position. Furthermore, the key issue is the deformation of the inlet section increases to a stable level in a certain range, while the ground settlement does not exceed the threshold. The selection of pipe-roof is controlled by calculated deformation. If the deformation meets the requirements, the internal force will be far enough to meet the requirements. Only two sections need to be considered when calculating the ultra-shallow buried underground passage, the entrances 2.0H and the central across section. Finally, the accuracy of the interactive effects calculated method is validated by using the measured data of a practical example.
Chaoyang Heng,Song Sun,Zhi Zhou,Jiantao Zhang 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.11
Based on the actual measured surface settlement of two super-shallow buried large rectangular-section urban underpass, a settlement fitting function is established. The superposition curve used the reduction of settlement trough. By comparing the results of fitting analysis with Peck formula result, settlement characteristics and simple prediction method for super-shallow and large rectangular section urban underpass are proposed, including: 1) The settlement trough is a superposition of three normal distribution curves, with the maximum surface settlement appeared above the central line of each single passage; 2) The depth and width of the middle passage settlement trough should be uniformly reduced. The reduction coefficient is calculated based on the ratio of the middle passage width to the side passage; 3) The loss rate of the side passage is 0.7% − 1.0%, while it is 0.4% − 0.6% for the middle passage, 4) If the underpass is excavated in staggered sequence, the peck formula can be used to calculate the surface settlement. The surface settlement of a single passage is calculated firstly, and then the surface settlement of three passages is superimposed to obtain the final settlement.