• Bulletin of the Korean Chemical Society
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• v.33 no.2
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• pp.387-392
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• 2012

A series of Pd-based catalysts were prepared and examined for the amination of 2,6-dimethylphenol in a fixedbed reactor. The best results were obtained for Pd/$Al_2O_3$-BaO with a conversion of 99.89% and a selectivity of 91.16%. These catalysts were characterized using BET, XRD, XPS, TEM and $NH_3$-TPD. Doped BaO not only improved the dispersion of the Pd particles but also decreased the acidity of the catalyst, which remarkably enhanced the selectivity and stability of the catalyst. The generality of Pd/$Al_2O_3$-BaO for this kind of reaction was demonstrated by catalytic aminations of o- and p-alkyl phenols.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.248-251
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• 2000

The ATM-PON is regarded as an effective access network because the system transmits the various user's information through the passive optical splitter in a single platform. The ranging technology is to place all ONUs at the same distance virtually in order to form ATM-PON based on the Time Division Multiplexing (TDM). In This paper, We show the steps about ranging protocol based on ITU-T G.983.1 and ranging procedure modeling. Also, We implement the simulator that considers various environments to verify the time specifications of G.983.1. By using the simulator, We find out the wasted bandwidth which influences active ONUs during the ranging procedure.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.1
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• pp.20-27
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• 2007

An analytic design guide was formulated for the design of 3-stage CMOS OP amp with the nested Gm-C(NGCC) frequency compensation. The proposed design guide generates straight-forwardly the design parameters such as the W/L ratio and current of each transistor from the given design specifications, such as, gain-bandwidth, phase margin, the ratio of compensation capacitance to load capacitance. The applications of this design guide to the two cases of 10pF and 100pF load capacitances, shows that the designed OP amp work with a reasonable performance in both cases, for the range of compensation capacitance from 10% to 100% of load capacitance.

• Journal of Electrochemical Science and Technology
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• v.8 no.3
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• pp.236-243
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• 2017

A fixed-bed zinc/nickel redox flow battery (RFB) is designed and developed. The proposed cell has been established in the form of a fixed bed RFB. The zinc electrode is immersed in an aqueous NaOH solution (anolyte solution) and the nickel electrode is immersed in the catholyte solution which is a mixture of potassium ferrocyanide, potassium ferricyanide and sodium hydroxide as the supporting electrolyte. In the present work, the electrode area has been maximized to $1500cm^2$ to enforce an increase in the energy efficiency up to 77.02% at a current density $0.06mA/cm^2$ using a flow rate $35cm^3/s$, a concentration of the anolyte solution is $1.5mol\;L^{-1}$ NaOH and the catholyte solution is $1.5mol\;L^{-1}$ NaOH as a supporting electrolyte mixed with $0.2mol\;L^{-1}$ equimolar of potassium ferrocyanide and potassium ferricyanide. The outlined results from this study are described on the basis of battery performance with respect to the current density, velocity in different electrolytes conditions, energy efficiency, voltage efficiency and power of the battery.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.340-343
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• 1992

Fundamental positioning characteristics of a dual-axis Sawyer linear motor are described. The Sawyer motor is capable of high positional accuracy. An electronic control unit of the motor whose velocity is proportional to the frequency of the electric current was produced in our laboratory. The positioning system was constructed using two Sawyer motors, an air bearings suspension unit and an electronic control unit. The stable motion of the motor was confirmed on the open loop operation. The adjustable operating conditions were the live load of 1 kg, the maximum acceleration of 1.2G and the maximum velocity of 350 mm/s. Absolute positioning accuracy was improved within .+-.5.mu.m, on microstep operating conditions of dividing one pitch of 508.mu.m into 508 steps. The following two conclusions were obtained. An accelerating-cruising-decelerating control is effective for reduction in the travel time required. Also, microstep operation is effective for improving the resolution of position.

• Journal of Electrochemical Science and Technology
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• v.7 no.2
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• pp.97-114
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• 2016

Lithium batteries based on elemental sulfur as the cathode-active material capture great attraction due to the high theoretical capacity, easy availability, low cost and non-toxicity of sulfur. Although lithium/sulfur (Li/S) primary cells were known much earlier, the interest in developing Li/S secondary batteries that can deliver high energy and high power was actively pursued since early 1990’s. A lot of technical challenges including the low conductivity of sulfur, dissolution of sulfur-reduction products in the electrolyte leading to their migration away from the cathode, and deposition of solid reaction products on cathode matrix had to be tackled to realize a high and stable performance from rechargeable Li/S cells. This article presents briefly an overview of the studies pertaining to the different aspects of Li/S batteries including those that deal with the sulfur electrode, electrolytes, lithium anode and configuration of the batteries.

• Journal of Sensor Science and Technology
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• v.26 no.5
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• pp.360-365
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• 2017

In this study, a heat treatment process was applied to ZnS nano-powder to improve the optical properties of ZnS ceramic, and the characteristics of heat treatment time were studied. The ZnS nano-powders were synthesized by hydrothermal synthesis. The heat treatment was carried out at $550^{\circ}C$ for 0.5, 1, 2, and 4 hours in a vacuum atmosphere ($10^{-2}torr$). X-ray diffraction and scanning electron microscope analyzes confirmed the change of crystal phase and grain size to confirm the structural change with heat treatment time. The heat treated ZnS nano-powder was sintered by hot pressing, and the change of optical properties of the ZnS ceramic was analyzed by infrared spectroscopy.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.6
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• pp.660-666
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• 2015

To avoid radiation exposure from repeated x-rays taken during orthopedic surgery, an x-ray permeable teleoperated Stewart platform for orthopedic fracture surgery was developed. This system is composed of a user interface device and a teleoperated operational robot, both of which use a Stewart platform mechanism. The links of the operational robot are made from an x-ray permeable material, polycarbonate, to minimize the interference. The forward and inverse kinematics algorithm applied and the structural reliability were both verified through an analysis using commercial engineering software. To monitor the operating status in real time and stop the device during an emergency, a monitoring software was developed. The performance of the x-ray permeable teleoperated Steward platform was validated experimentally.

• Journal of the Korean Ceramic Society
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• v.51 no.4
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• pp.332-336
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• 2014

A non-electric water purification system using the Korean traditional ceramic ware Onggi, was demonstrated as an appropriate technology to solve water shortages in under developed regions. Generally, Onggi is produced using large size raw materials that are sintered at low temperature, resulting in a porous body that shows air and water permeability. An Onggi filter was prepared using a spinning wheel with the addition of rice bran to the body to increase porosity. The porosity of the obtained Onggi filter was 25.1%; the water permeability was 85.1 $L/m^2h$. Turbidity and TDS of the purified water using Onggi filter were decreased by 97.7% and 29.1%, respectively.

• Corrosion Science and Technology
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• v.7 no.5
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• pp.265-268
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• 2008

Prestressed Concrete Cylinder Pipe(PCCP) had became one of the dominating kinds of pipes substituting for steel pipes because of its unique feature (high intensity, high pressure and high leakproofness). PCCP was produced firstly by Bonna company in France. By the end of 20th century, there were over 19000 km of this product installed in America. PCCP was introduced from Ameron company by Shandong Eletric Power Pipeline Engineering Company in 1988. As the statistical data in 2002, 700 km of PCCP had been applied in China, and the application trended towards rapid increase.Since prestressing wire would be corroded in environment, Several accidents due to the breakdown of pipe had happened. Consequently the external wall of pipe should be covered with protective coatings. There was a lack of technical study in corrosion and control of PCCP, because PCCP had been applied for a short time in China. in order to ensure the service life of PCCP, we have developed a kind of protective coating for concrete pipe, which had high intensity and anti-corrosive property with convenient applicability. The physical and chemical properties, painting technology and field application of this coating was introduced in the paper, at the same time, the future of external protective coating for PCCP was looked into.