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New PWM Technique for Two-Phase Brushless DC Motor Drives
Hai Lin,Byung-il Kwon 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.5
A new PWM technique for a two-phase BLDC motor fed by a two-phase eight-switch inverter is proposed in this paper. It is well known that a two-phase eight-switch inverter can significantly improve power output compared with a two-phase six-switch inverter in a two-phase motor drive. To drive the two-phase BLDC motor simply and effectively, two normal PWM strategies are investigated to manage speed regulation. However, under the conditions of low speed and light load, especially during the braking process, the current in a short time of one period is near zero, which is a discontinuous waveform every half period. To solve it, a novel PWM technique is investigated to improve the operational performance of normal technique. Using the new PWM scheme, the current continues every half period and the braking performance is improved. The effectiveness of the proposed PWM method is verified through the experiments.
Hai Lin Liao,Bin Wang,Weyman Jones Tom 연세대학교 동서문제연구원 2007 Global economic review Vol.36 No.4
There has been a long tradition in business and economics to use frontier analysis to assess a production unit`s performance. The first attempt utilized the data envelopment analysis (DEA) which is based on a piecewise linear and mathematical programming approach, whilst the other employed the parametric approach to estimate the stochastic frontier function. Both approaches have their advantages as well as limitations. This paper sets out to use an alternative approach, i.e. artificial neural networks (ANNs) for measuring efficiency and productivity growth for seven East Asian economies at manufacturing level, for the period 1963 to 1998, and the relevant comparisons are carried out between DEA and ANN, and stochastic frontier analysis (SFA) and ANN in order to test the ability of ANNs to assess the performance of production units. The results suggest that ANNs are a promising alternative to traditional approaches, to approximate production functions more accurately and measure efficiency and productivity under non-linear contexts, with minimum assumptions.
Numerical approach to fracture behavior of CFRP/concrete bonded interfaces
Hai X. Lin,Jian Y. Lu,Bing Xu 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.3
Tests on the fracture behavior of CFRP-concrete composite bonded interfaces have been extensively carried out. In this study, a progressive damage model is employed to simulate the fracture behaviors. The crack nucleation, propagation and more other details can be captured by these models. The numerical results indicate the fracture patterns seem to depend on the relative magnitudes of the interface cohesive strength and concrete tensile strength. The fracture pattern transits from the predominated adhesive-concrete interface debonding to the dominated concrete cohesive cracking as the interface cohesive strength changes from lower than concrete tensile strength to higher than that. The numerical results have an agreement with the experimental results.
Chemically Modified Sepharose as Support for the Immobilization of Cholesterol Oxidase
( Hai Lin Yang ),( Yi Chen ),( Yu Xin ),( Ling Zhang ),( Yu Ran Zhang ),( Wu Wang ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.9
Because the cholesterol oxidase from Brevibacterium sp. M201008 was not as stable as the free enzyme form, it had been covalently immobilized onto chemically modified Sepharose particles via N-ethyl-N`-3-dimethylaminopropyl carbodiimide. The optimum immobilization conditions were determined, and the immobilized enzyme activity obtained was 12.01 U/g Sepharose-ethylenediamine. The immobilization of the enzyme was characterized by Fourier transform infrared spectroscopy. The immobilized enzyme exhibited the maximal activity at 35oC and pH 7.5, which was unchanged compared with the free form. After being repeatedly used 20 times, the immobilized enzyme retained more than 40.43% of its original activity. The immobilized enzyme showed better operational stability, including wider thermal and pH ranges, and retained 62.87% activity after 20 days of storage at 4oC, which was longer than the free enzyme.
Hai Lin Zhao,Yeong Shik Kim 대한약학회 2004 Archives of Pharmacal Research Vol.27 No.9
A 1, 2-diglyceride-based multi-step colorimetric assay to measure the pancreatic lipase activity was applied for the determination of the kinetic profiles of the lipase inhibition with a slight modification and the validity verification. With this assay method, our study revealed that platycodin D, one of major constituents of Platycodi Radix, inhibits the pancreatic lipase activity in a competitive type, with the value of KI being 0.18±0.02 mM. In addition, PD has affected the values of Km, app and Kcat/Km in a dose- dependent manner. The results shed a meaningful light on how PD mediates lipid metabolism in the intestinal tracts. On the other hand, since the revised assay is sensitive, rapid, and does not affect the accuracy to the kinetic properties, it is applicable not only to evaluation of the kinetic properties of the pancreatic lipase, but also to highthroughput screening of pancreatic lipase activity.
Hai Yan Zhang,Yingxi Lin,Danfeng Zhang,Wenguang Wang,Yuxiong Xing,Jin Lin,Haoqun Hong,Chunhui Li 한국물리학회 2016 Current Applied Physics Vol.16 No.12
Heat dissipation from light-emitting diodes (LEDs) has become a serious problem because of the LEDs' high luminosity and power. This problem could be solved by improving the dissipation efficiency of each LED system component. A microwave-reduced graphene nanosheet/silicone (GN/silicone) composite with a high thermal conductivity and stability was prepared by mechanical blending. The thermal conductivity of the composite reaches 2.7 W/(m K) with only 1.5 wt% loading, and is 12 times higher than the pure silicone matrix. When used as a thermal interface material between high-power LED chip module substrates and heat sinks, the thermal conductive GN/silicone composite could decrease the temperature difference between the substrate and shell. It could also improve the system heat transfer efficiency. The temperature gap between the heat slug and the heat sink was less than 2 C with a 1.5 wt% loading of GNs.
Original Articles : A New Rat Model of Cisplatin-induced Neuropathic Pain
( Hai Lin ),( Bong Ha Heo ),( Myung Ha Yoon ) 대한통증학회 2015 The Korean Journal of Pain Vol.28 No.4
Background: Chemotherapy-induced peripheral neuropathy is a major side effect of anti-cancer drugs, and our knowledge of its mechanisms is lacking. Several models for chemotherapy-induced neuropathy have been introduced. However, the outcomes of these models differ significantly among laboratories. Our object was to create a model of chemotherapy-induced neuropathy in rats with cancer. Methods: Female Sprague-Dawley rats were used. Mammary rat metastasis tumor (MRMT-1) cells were implanted subcutaneously in rats. Chemotherapy-induced peripheral neuropathy was induced by injection of cisplatin once a day for four days. The responses to mechanical and thermal stimuli were examined using von Frey filaments, acetone, and radiant heat. Results: Cisplatin (2 mg/kg/day) produced mechanical allodynia, while it did not induce cold allodynia or thermal hyperalgesia. This dose of cisplatin could work successfully against cancer. Body weight loss was not observed in cisplatin-treated rats, nor were other abnormal behaviors noted in the same rats. Conclusions: Repeated injection of intraperitoneal cisplatin induced peripheral neuropathic pain in rats. Thus, this type of rat model has broad applicability in studies related to searching for the mechanism of cisplatin-induced mechanical allodynia and agents for the treatment of neuropathic pain. (Korean J Pain 2015; 28: 236-243)
Hai Lin,Kyu-Yun Hwang,Byung-Il Kwon 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.3
This paper investigates an improved stator flux linkage observer for sensorless permanent magnet synchronous motor (PMSM) drives using a voltage-based flux linkage model and an adaptive sliding mode variable structure. We propose a new observer design that employs an improved sliding mode reaching law to achieve better estimation accuracy. The design includes two models and two adaptive estimating laws, and we illustrate that the design is stable using the Popov hyper-stability theory. Simulation and experimental results demonstrate that the proposed estimator accurately calculates the speed, the stator flux linkage, and the resistance while overcoming the shortcomings of traditional estimators.