• Journal of the Korean Vacuum Society
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• v.11 no.4
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• pp.230-234
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• 2002

Metal-ferroelectric-semiconductor(MFS) capacitors by using rapid thermal annealed $LiNbO_3$/Si structures were successfully fabricated and demonstrated nonvolatile memory operations of the MFS capacitors. The C-V characteristics of MFS capacitors showed a hysteresis loop due to the ferroelectric nature of the $LiNbO_3$thin film. The dielectric constant of the $LiNbO_3$film calculated from the capacitance in the accumulation region in the capacitance-voltage(C-V) curve was about 25. The gate leakage current density of MFS capacitor using a platinum electrode showed the least value of $1{\times}10^{-8}\textrm{A/cm}^2$ order at the electric field of 500 kV/cm. The minimum interface trap density around midgap was estimated to be about $10^{11}/cm^2$.eV. The typical measured remnant polarization(2Pr) value was about 1.2 $\mu\textrm{C/cm}^2$, in an applied electric field of $\pm$ 300 kv/cm. The ferroelectric capacitors showed no polarization degradation up to about $10^{10}$ switching cycles when subjected to symmetric bipolar voltage pulse in the 500 kHz.

• Korean Journal of Materials Research
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• v.10 no.7
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• pp.471-477
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• 2000

Corrosion behavior of Fe-Ni-Cr alloy in molten salts of LiCl and LiCl-$Li_2O was investigated in the tempera-ture range of $650~850^{\circ}C$. In the molten salt of LiCl, and internal oxidation of Fe occurred in the KSA(Kaeri Superalloy)-1 alloy without containing Cr, while a dense protective oxide scale of $LiCrO_2$ was formed in the KSA-4, Incoloy 800H and KSA-5 alloys. In the mixed molten salt of LiCl-$Li_2O$, internal oxidation of Fe and Cr took place in the KSA-1 and KSA-4 alloys, respectively. Non-protective porous oxide scales consisting of $LiCrO_2$ and Ni were formed in the Incoloy 800H and KSA-5. The corrosion rate of the alloys increased with the increase in Cr content and the corrosion rate followed the parabolic law for the alloy containing Cr content less than 8%, and the linear law for the alloy containing Cr content more than 8%. Such a corrosion behavior of the alloy in the mixed molten salt of LiCl-$Li_2O$ was interpreted in terms of the basic fluxing mechanism of protective oxide scale of $Cr_2O_3$.

• Journal of the Korean Electrochemical Society
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• v.13 no.2
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• pp.103-109
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• 2010

$Li_4Mn_5O_{12}$ was synthesized by combustion method using $LiNO_3$, $Li(CH_3COO){\cdot}2H_2O$ and $Mn(CH_3COO)_2{\cdot}4H_2O$. $Li_4Mn_5O_{12}$ was obtained over $400^{\circ}C$, however, the sample calcined at $400^{\circ}C$ for any time was mixed phases of $Li_4Mn_5O_{12}$ and $Mn_2O_3$. $Li_4Mn_5O_{12}$ calcined at $400^{\circ}C$ for 5 h had larger first discharge capacity (41.5mAh/g) at 1C-rate for 3.7~4.4V than other calcined samples. Moreover, applying to hybrid capacitor, it had good discharge capacity (24.74 mAh/g or 10.46 mAh/cc) at 100 mA/g for 1~2.5 V and higher energy density (39Wh/kg or 16.49Wh/cc) at same condition.

• Korean Journal of Remote Sensing
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• v.39 no.5_2
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• pp.849-858
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• 2023

Investigating disaster sites such as earthquakes and landslides involves significant risks due to potential secondary disasters like facility collapse. In situations where direct access is challenging, there is a need to develop methods for safely acquiring high-precision 3D disaster information using light detection and ranging (LiDAR) equipped drone survey systems. In this study, the feasibility of using drone LiDAR in disaster scenarios was examined, focusing on the collapse accident at Jeongja Bridge in Bundang-gu, Seongnam City, in April 2023. High-density point clouds for the accident bridge were collected, and the bridge's 3D terrain information was reconstructed and compared to the measurement performance of 10 ground control points. The results showed horizontal and vertical root mean square error values of 0.032 m and 0.055 m, respectively. Additionally, when compared to a point cloud generated using ground LiDAR for the same target area, a vertical difference of approximately 0.08 m was observed, but overall shapes showed minimal discrepancies. Moreover, in terms of overall data acquisition and processing time, drone LiDAR was found to be more efficient than ground LiDAR. Therefore, the use of drone LiDAR in disaster sites with significant risks allows for safe and rapid onsite investigations.

• Journal of Internet of Things and Convergence
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• v.6 no.4
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• pp.49-57
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• 2020

In this paper, I provided an approximation function Li*2,10(x) using logarithm integral for the counting function π*2,10(x) of consecutive deca primes. Several personal computers and Mathematica were used to validate the approximation function Li*2,10(x). I found the real value of π*2,10(x) and approximate value of Li*2,10(x) for various x ≤ 1011. By the result of theses calculations, most of the error rates are margins of error of 0.005%. Also, I proved that the sum C2,10(∞) of reciprocals of all primes with difference 10 between primes is finite. To find C2,10(∞), I computed the sum C2,10(x) of reciprocals of all consecutive deca primes for various x ≤ 1011 and I estimate that C2,10(∞) probably lies in the range C2,10(∞)=0.4176±2.1×10-3.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.12
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• pp.1283-1288
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• 2004

Metal-ferroelectric-insulator-semiconductor(WFIS) capacitors using rapid thermal annealed LiNbO$_3$/AlN/Si(100) structure were fabricated and demonstrated nonvolatile memory operations. The capacitors on highly doped Si wafer showed hysteresis behavior like a butterfly shape due to the ferroelectric nature of the LiNbO$_3$ films. The typical dielectric constant value of LiNbO$_3$ film in the MFIS device was about 27, The gate leakage current density of the MFIS capacitor was 10$^{-9}$ A/cm$^2$ order at the electric field of 500 kV/cm. The typical measured remnant polarization(2P$_{r}$) and coercive filed(Ec) values were about 1.2 $\mu$C/cm$^2$ and 120 kV/cm, respectively The ferroelectric capacitors showed no polarization degradation up to 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulses of 1 MHz. The switching charges degraded only by 10 % of their initial values after 4 days at room temperature.e.

• Korean Journal of Acupuncture
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• v.31 no.4
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• pp.240-246
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• 2014

Objectives : The purpose of this study is to report the clinical effects of Korean medical treatment with Hominis Placenta Pharmacopunture(HPP) on cold hypersensitivity of hands. Methods : A 46-year-old female patient whose chief complaint was cold hypersensitivity of hands was treated with Placenta Pharmacopunture at LI4 and LI10, ten times for a month. Acupuncture and herbal medicine were added depending on the symptoms. Digital Infrared Thermal Imaging(D.I.T.I) was taken and Visual Analog Scale(VAS) was examined before and after each treatment. Results : After the treatments, the symptoms were improved. Conclusions : DITI and VAS showed that the patient's cold hypersensitivity of hands was improved after Korean medical treatment with Hominis Placenta Pharmacopuncture.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.605-608
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• 1998

In this paper, we have investigated the pyroelectric characteristics of the $20\mu\textrm{m}-thick$ $LiTaO_3$ single crystal with black coating by using the nondestructive dynamic method. The $LiTaO_3shows$ the maximum pyroelectric coefficient (${\gamma}$) of $1.56$\times$10-8C/\textrm{cm}^2K$ at 40Hz and the responsivity (Rv) is 488V/W at 2Hz. The noise equivalent power (NEP) is obtained as 3.95$\times$10-10W/√Hz at 40Hz. The detectivity (D*) is obtained divided by the sample area and estimated to be 5.6$\times$108cm√Hz/W at 40Hz. These results, shows that the $LiTaO_3$ single crystals are the best candidates to pyroelectric IR sensors.

• Bulletin of the Korean Chemical Society
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• v.35 no.10
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• pp.2901-2905
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• 2014

The hierarchical-structured $LiFePO_4$ cathode materials were synthesized by one-step microwave synthesis, and their electrochemical properties were investigated. Addition of citric acid during the reaction lead to the formation of hierarchical structured $LiFePO_4$, which has both nano- and micron-characteristics advantageous for energy density and electrode fabrication. Adjusting the molar ratio of Fe to citric acid enhanced the electrochemical properties of $LiFePO_4$.

• Bulletin of the Korean Chemical Society
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• v.21 no.10
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• pp.1047-1048
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• 2000

Dye-sensitized nanocrystalline rutile $TiO_2$ solar cells were prepared, and the influence of Li+ and 1,2-dimethyl-3-hexyl imidazolium ions in the electrolyte on the photovoltaic properties was compared. The electrolyte con-taining Li+ ions produced a lower open-circuit photovoltage than the electrolyte with 1,2-dimethyl-3-hexyl im-idazolium ions, suggesting that the adsorption of Li+ ions to the rutile $TiO_2$ surface causes a shift in the band edges toward more positive potentials. At the same time, both the short-circuit photocurrent and the maximum value of the incident-photon-current conversion efficiency (IPCE) of the electrolyte containing Li+ ions were relatively higher. Data analysis suggests that presence of adsorbed Li+ ions improves via the phenomenon of band-edge movement the charge-injection efficiency by altering both the energy and number of excited state levels of the dye that participate in electron injection.