• Journal of Electrochemical Science and Technology
• /
• v.14 no.2
• /
• pp.139-144
• /
• 2023

In this study, carbon-coated porous nanofibers were prepared via electrospinning and the performance of Li[Ni_0.93Co_0.07]O₂ (NC) synthesized by electrospinning (E-NC) and co-precipitation (C-NC) was compared. E-NC had a discharge capacity of 206 mAh g^-1 at 0.1C (17 mA/g), which is 10% higher than that of C-NC (189.2 mAh g^-1). E-NC shows a high-rate performance of 118.32 mAh g^-1 (61.7%) at 5C (850 mA/g), which is 50% higher than that of C-NC (78.22 mAh g^-1 = 45.7%). Charge transfer of the carbon-coated porous nanofiber E-NC decreased by 35% compared to C-NC after 20 cycles as observed using electrochemical impedance spectroscopy. The results of this study show that the nanofiber structure with carbon coating shortens the Li-ion diffusion path, improves electrical conductivity, resulting in excellent rate performance.

• Journal of the Semiconductor & Display Technology
• /
• v.14 no.1
• /
• pp.31-37
• /
• 2015

This paper is on the design and manufacturing of vibration tester (shaker) for experiments about effects on the performance of semiconductor chips and Li-ion batteries by vibration. Shaker in the market are quite expensive, it is difficult for basic researchers to contact. In this study, in order to improve this, we designed and manufactured with an entry-level into mass production possible approaches in terms of performance required to a minimum. The shaker system is operated by Matlab and LabView. The target performances are 200Hz frequency and 5% error, and these were satisfied.

• Korean Journal of Crystallography
• /
• v.14 no.2
• /
• pp.110-114
• /
• 2003

LiAl/sub 0.24/Mn/sub 1.76/O/sub 4-y/S/sub y/ (y=0, 0.02) were synthesized by the sol-gel method. Both structures were refined by Rietveld method, its structure refined as a cubic spinel, space group Fd-3m, a=8.17937(30) Å and 8.18331(19) Å respectively. Though it has been made a charge/discharge experiment above 20 times, there was no change of 3 V/4 V capacity degradation. It was considered that the volume change of MnO/sub 6/ octahedron induced by sulfur substitution plays a key role in keeping the 3 V/4 V capacity. The refined composition of the compound could be confirmed with the ICP analysis.

• Journal of the Korean Ceramic Society
• /
• v.27 no.3
• /
• pp.430-436
• /
• 1990

Glasses of different compositions were synthesized by substituting each component of 56ZrF4-14BaF2-6LaF3-4AlF3-20NaF(ZBLAN) with HfH4, SrF2, GdF3, InF3 and LiF3, each of similar size and chemical property with the component being substituted, respectively. The heating rate used in the DSC runs was 10K/min. All ofthe glasses exhibit glass transition temperatures of 510$\pm$10K, while crystallization temperatures vary between 625 and 720K depending upon different glass compositions. For most glasses crystallization temperatures obtained while cooled are lower than those obtained while heated, but InF3 or SrF2 containing glasses showed opposite trend. HBLAN, ZHBLAN and ZHBLANLi glasses, which were made by substituting HfH4, LiF for ZrF4 and NaF of ZBLAN respectively, showed improvement in the glass stability.

• Proceedings of the KIPE Conference
• /
• 2010.07a
• /
• pp.420-421
• /
• 2010

In this paper, a multi-module selective battery equalizer for series-connected Li-ion battery pack is proposed. Selective Equalizer (SE) scheme achieves smaller volume and lighter weight than individual cell equalizer (ICE) by minimizing the part count of bulky circuit element. However, SE scheme shows slow balancing speed when the voltage imbalance simultaneously occurs in more than one cell. The proposed multi-module overcomes the problem by employing multiple power converters. Prototype hardware is implemented and experimented with 14Ah battery cells to validate the performance of the proposed equalizer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.10
• /
• pp.825-832
• /
• 2002

The present study investigated the enhancement of the absorption performance by the spring wrapped around the outer surface of the vertical falling film absorber tube. Heat and mass transfer enhancements were experimentally investigated, and flow visualization was performed to observe the wettability and flow pattern of the solution. The key experimental parameters were spring diameter (0.5, 1.0 mm) and spring pitch (1, 3, 10 mm), film Reynolds number (50~150), and concentration of LiBr-$H_2O$ solution (55, 60, 65 wt%). As the spring diameter was increased, the absorption mass flux, Sherwood number, Nusselt number, heat flux, and heat transfer coefficient were increased The Nusselt and Sherwood numbers showed the maximum at the spring pitch of 3mm, and the ratio of pitch to diameter of approximately 3 and 6 for the spring diamter of 0.5 mm, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
• /
• v.14 no.8
• /
• pp.641-647
• /
• 2002

Objectives of this paper are to investigate the effect of roughness of micro-hatching tubes on the absorption performance and to develop on experimental correlation of Nusselt as a function of the roughness. Three different micro-scale hatched tubes and a bare tube were tested in the present experiment. $H_{2}O/LiBr$ solution is used as working fluid. It was found that absorption performance of micro-scale hatched tubes were improved upto 2 times with an error band of ${\pm}25%$ compared with the bare tube. An experimental correlation of Nusselt was developed as a function of the roughness.

• Journal of the Optical Society of Korea
• /
• v.6 no.2
• /
• pp.27-32
• /
• 2002

An integrated optical 2$\times$2 add/drop multiplexer in X-cut, Y-propagating LiNbO$_3$ has been demonstrated. The device consists of passive polarization splitters and acousto-optical mode converters with weighted coupling utilizing tapered acoustical directional couplers; their specific design and properties are discussed. The insertion loss has been measured to be about -8.16 ㏈ and -8.6 ㏈ for TE and TM polarizations, respectively. The device shows a 3 ㏈ bandwidth of 2.3 nm, a tuning rate 8.34 nm/MHz around λ = 1554 nm, and a sidelobe suppression of about 14.5 ㏈. Optimum operation is achieved with a RF drive power of about 43 ㎽. Multi-wavelength operation has been demonstrated.

• Current Optics and Photonics
• /
• v.2 no.6
• /
• pp.606-611
• /
• 2018

Measurement of the nonlinear optical coefficients is not an easy task since it requires complicated experimental setup and analysis. We suggest an easy way to estimate the relative nonlinear optical tensor components by direct measurement of the output powers of the second harmonic generation and spontaneous parametric down conversion experiments. The experiments were done in quasi-phase-matched type-0 as well as type-1 interactions at similar pump wavelengths in a 5% MgO-doped periodically poled $LiNbO_3$ crystal to obtain the ratio of the nonlinear optical tensor components $d_{33}/d_{31}$ in each experiment. The obtained ratios were then compared with the previously ascertained values [J. Opt. Soc. Am. B, 14, 2268-2294 (1997)].

• Korean Journal of Medicinal Crop Science
• /
• v.13 no.2
• /
• pp.126-130
• /
• 2005

Acifluorfen tolerance charateristics determined the involvement of absorption, translocation, and metabolism in acifluorfen tolerance. Less than 6% of the applied $^{14}C-acifluorfen$ was absorbed. There were no differences in acifluorfen absorption between susceptible and tolerant somaclones. More $^{14}C-acifluorfen$ was translocated in the susceptible than the tolerant somaclones. The susceptible somaclone did not metabolize acifluorfen while some somaclones (i.e.,EBN-3A) metabolized $^{14}C-acifluorfen$. Nomenclature: Acifluorfen, 5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid; eastern black night shade, Solanum ptycanthum Dun.,$#^3$ SOLPT.