• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.1-13
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• 2024

This paper presents applications of lithium-sulfur (Li-S) energy storage batteries, while showing merits and demerits of several techniques to mitigate their electrochemical challenges. Unmanned aerial vehicles, electric cars, and grid-scale energy storage systems represent main applications of Li-S batteries due to their low cost, high specific capacity, and light weight. However, polysulfide shuttle effects, low conductivities, and low coulombic efficiencies signify key challenges of Li-S batteries, causing high volumetric changes, dendritic growths, and limited cycling performances. Solid-state electrolytes, interfacial interlayers, and electrocatalysts denote promising methods to mitigate such challenges. Moreover, nanomaterials have capability to improve kinetic reactions of Li-S batteries based on several properties of nanoparticles to immobilize sulfur in cathodes, stabilizing lithium in anodes while controlling volumetric growths. Li-S energy storage technologies are able to satisfy requirements of future markets for advanced rechargeable batteries with high-power densities and low costs, considering environmentally friendly systems based on renewable energy sources.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.132.2-132.2
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• 2010

Mesoporous tinoxide ($SnO_2$) as anode materials for Li-ion battery were prepared by hydrothermal method and templating method using SBA-15 as template. And electrochemical properties of $SnO_2$ electrode were investigated with cyclic voltammogram (CV). The morphology and structures of $SnO_2$ were characterized by transmission electron microscopy (TEM) and X-ray diffractometer (XRD), respectively. The specific surface area was defined by $N_2$ adsorption with BET(Brunauer-Emmett-Teller) method. As a result, the surface area of mesoporous $SnO_2$ which was made from templating method is higher than the case of using hydrothermal method. In addition, in anodic performance, mesoporous $SnO_2$ which is prepared by templating method showed higher charge-discharge capasity compared to hydrothermal method and exhibited excellent stability over the entire cycle number. It was indicated that electrochemical performances of mesoporous $SnO_2$mainly affected to the structural features, such as specific surface area and porosity.

• The Journal of Information Technology
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• v.7 no.2
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• pp.43-54
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• 2004

Since Dr. John J. Hopfield has proposed the HOpfield network, it has been widely applied to the pattern recognition and the routing optimization. The method of Jian-Hua Li improved efficiency of Hopfield network which input pattern's weights are regenerated by SVD(singluar value decomposition). This paper deals with Li's Hopfield Network by linear pre-processing. Linear pre-processing is used for increasing orthogonality of input pattern set. Two methods of pre-processing are used, Hadamard method and random method. In manner of success rate, radom method improves maximum 30 percent than the original and hadamard method improves maximum 15 percent. In manner of success time, random method decreases maximum 5 iterations and hadamard method decreases maximum 2.5 iterations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.3
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• pp.258-263
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• 2002

We present a new toed phosphor, $Gd_{2-x-y}Li_xEu_yO_3$ with superior luminescent Properties compared to the commercially available red phosphor $Y_2O_3:Eu^{3+}$. The phosphor, with a diameter of about $2\mu\textrm{m}$, consists of the psedospherical particles in a regular array. The photoluminescence measurements as a function of the laser power and the Eu mole fraction were performed at zoom temperature The luminescence intensity linearly increases as both the laser power and the Eu mole fraction Increase. As for the dependence on cathodoluminescence, the incorporation of Eu and Li ions into $Gd_2O_3$ lattice brings about an increase in luminescent efficiency. The highest emission intensity for the phosphor occurs at the applied voltage of 500 V, its value is larger than that of $Y_2O_3:Eu^{3+}$ powder by 70%.

• Korean Journal of Optics and Photonics
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• v.15 no.2
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• pp.142-148
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• 2004

We investigated a Ti:LiNbO$_3$ based integrated-optic polarization controller with a Ti-indiffused waveguide along the z-axis utilizing the electro-optic effect. The device consists of a first quarter-wave (λ/4) phase-shifter followed by a half-wave(λ/2) and a second quarter-wave(λ/4) wave-plate, which is rotated synchronously with the first quarter-wave phase-shifter. We analyzed the operation principles of the device utilizing cascaded transfer matrices based on Jones matrix and Poincare sphere, simulated driving voltages for various input states of polarization (SOP), and theoretically confirmed transformations from any arbitrary input SOP into any general output SOP.

• Bulletin of the Korean Chemical Society
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• v.31 no.8
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• pp.2304-2308
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• 2010

A $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ (LNCAO/C) active material composite cathode was coated with carbon. The conductive carbon coating was obtained by addition of surfactant during synthesis. The addition of surfactant led to the formation of an amorphous carbon coating layer on the pristine LNCAO surface. The layer of carbon coating was clearly detected by FE-TEM analysis. In electrochemical performance, although the LNCAO/C showed similar capacity at low C-rate conditions, the rate capability was improved by the form of the carbon coating at high current discharge state. After 40 cycles of charge-discharge processes, the capacity retention of LNCAO/C was better than that of LNCAO. The carbon coating is effectively protected the surface structure of the pristine LNCAO during Li insertion-extraction.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.127-130
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• 2002

In this study, development of a new LTCC material using a non-glassy system was attempted with respect to reducing the fabrication process steps and cost down. Lowering the sintering temperature can be achieved by liquid phase sintering. For LTCC application, the starting material must have quality factor as high as possible in microwave frequency range. And also, the material should have a low dielectric constant for enhancing the signal propagation speed. Regarding these factors, dielectric constants of various materials were estimated by the Clausius-Mosotti equation. Among them, CaWO$_4$ was tamed out the suitable LTCC material. CaWO$_4$ can be sintered up to 98% of full density at 1200$^{\circ}C$ for 3 hours. It's measured dielectric constant, quality factor, and temperature coefficient of resonant frequency were 10.15, 62880GHz, and -27.8ppm/$^{\circ}C$, respectively. In order to modify the dielectric properties and densification temperature, 0.5∼1.5 wt% LiF were added to CaWO$_4$. LiF addition reduced the sintering temperature/time down to 800$^{\circ}C$/10∼30min due to the reactive liquid phase sintering. Dielectric constant lowered from 10.15 to 9.38 and Q x fo increased up to 92000GHz with increasing LiF content.

• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.15-17
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• 2005

In this study, tunable dielectric materials are important for resonator, variable capacitor, phased array antenna and other devices application. In this paper, Dielectric constant increased and tuning range increased with the increased of $BaSrTiO_3/Li_{2}CO_{3}$ content, which probably can be explained by the substitution of Ba3+, Li1+ on BaTiO3 lattice. The tunability and dielectric loss of the $BaSrTiO_2/Li_{2}CO_{3}$ thick film, sintered at $1150^{\circ}C$, were about 43 % and 0.234 at 10$\sim$15 MHz, respectively. In case of BaSrTi/MgO, Dielectric constant decreased and tenability increased with the added of $BaSrTiO_3/MgO$. The ferroelectrics properties were distinct when adding Li to BST ceramic thick film, and paraelectrics pattern was distinct when adding Mg.

• Korean Journal of Acupuncture
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• v.34 no.4
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• pp.271-276
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• 2017

Objectives : The purpose of this study is to report 4 cases of shoulder pain treated by Ligamentum Pharmacopuncture. Methods : This study on shoulder pain was carried out on 4 patients who were treated at Department of Acupuncture & Moxibusition, Dongshin University, Korean Medicine Hospital from May 2016 to July 2016. All patients were treated 2~3 times based on the patient's condition. To evaluate change of pain and function, we used Shoulder Pain and Disability Index(SPADI), Numeric Rating Scale(NRS) and Range Of Motion(ROM). Evaluations were made at baseline and one week and two weeks after treatment. Results : There was remarkable improvement in SPADI, NRS and ROM. Conclusions : This study suggested the possibility that the ligamentum pharmacopuncture therapy may be useful for the treatment of shoulder pain. Follow-up study is needed.

• Journal of Magnetics
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• v.15 no.1
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• pp.25-28
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• 2010

This study examined the crystallographic and magnetic properties of vanadium-substituted lithium cobalt titanium ferrite, $Li_{0.7}Co_{0.2}Ti_{0.2}V_{0.2}Fe_{1.7}O_4$. Ferrite was synthesized using a conventional ceramic method. The samples annealed below $1040^{\circ}C$ showed X-ray diffraction peaks for spinel and other phases. However, the sample annealed above $1040^{\circ}C$ showed a single spinel phase. The lattice constant of the sample was $8.351\;{\AA}$, which was relatively unaffected by vanadium-substitution. The average grain size after vanadium-substitution was $13.90\;{\mu}m$, as determined by scanning electron microscopy. The M$\ddot{o}$ssbauer spectrum could be fitted to two Zeeman sextets, which is the typical spinel ferrite spectra of $Fe^{3+}$ with A and B sites, and one doublet. From the absorption area ratio of the M$\ddot{o}$ssbauer spectrum, the cation distribution was found to be ($Co_{0.2}V_{0.2}Fe_{0.6})[Li_{0.7}Ti_{0.2}Fe_{1.1}]O_4$. Vibrating sample magnetometry revealed a saturation magnetization and coercivity of 36.9 emu/g and 88.6 Oe, respectively, which were decreased by vanadium-substitution.