• Journal of Korea Society of Industrial Information Systems
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• v.21 no.1
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• pp.17-25
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• 2016

This paper proposes an ultra-low power design methodology for asynchronous circuits which combines with power switch structure used for reducing leakage current in the synchronous circuits. Compared to existing delay-insensitive asynchronous circuits such as static NCL and semi-static NCL, the proposed methodology provides the leakage power reduction in the NULL mode due to the high Vth of the power switches and the switching power reduction at the switching moment due to the smaller area even though it has a reasonable speed penalty. Therefore, it will become a low power design methodology required for IoT system design placing more value on power than speed. In this paper, the proposed methodology has been evaluated by a $4{\times}4$ multiplier designed using 0.11 um CMOS technology, and the simulation results have been compared to the conventional asynchronous circuits in terms of circuit delay, area, switching power and leakage power.

• Bulletin of the Korean Chemical Society
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• v.27 no.8
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• pp.1171-1174
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• 2006

Various off-the-shelf Lewis acids in conjunction with various onium salts are screened for coupling reaction of $CO_2$ with epoxides. Among the tested ones, $VCl_3/n-Bu_4NOAc$, $VCl_3/(n-Bu_4NCl$ or PPNCl), $FeCl_3/ n-Bu_4NOAc$, and $FeCl_3/ n-Bu_4NOAc$are proved to be highly active. Propylene oxide, epichlorohydrin, styrene oxide, and cyclohexene oxide can be converted over 90% yields to the corresponding cyclic carbonates without the use of organic solvents under mild conditions by 0.1-1.0 mol% catalyst charge.

• Bulletin of the Korean Chemical Society
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• v.25 no.9
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• pp.1351-1354
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• 2004

Tetracyclic 5-azaindole analogues were prepared by palladium-catalyzed sequential annulation of benzylidene(3-iodopyridinyl-4-yl)amine and 1-aryl substituted internal alkynes under $Pd(OAc)_2,\;n-Bu_4NCl,\;and Et_3N\;at\;120^{\circ}C.$ The synthetic procedure showed possible diversification of tetracyclic 5-azaindole analogues by varying the 1-aryl substituent in internal alkynes.

• Archives of Pharmacal Research
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• v.29 no.6
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• pp.497-502
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• 2006

A new natural C-benzylated chalcone, $2',4'-dihydroxy-3'-(2-hydroxybenzyl)-6{\c}-methoxychalcone$ (2), along with two other flavonoids, tiliroside and kaempferol 3-O-rutinoside, and an oxoaporphine alkaloid, lanuginosine were isolated from the aerial parts of Ellipeiopsis cherrevensis (Annonaceae). Two known polyoxygenated cyclohexene derivatives, ferrudiol and zeylenol, and a new analog, ellipeiopsol D, were also isolated. The chalcone 2 exhibited cytotoxic activity against human small-cell lung-cancer (NCl-H187), epidermoid carcinoma (KB) and breast cancer (BC) cell lines with $IC_{50}$ values of 1.40, 5.31 and $13.92\;{\mu}g/mL$, respectively. This compound also showed antimalarial activity against Plasmodium falciparum with an $IC_{50}$ value of $7.1\;{\mu}g/mL$ as well as antimicrobacterial activity against Mycobacterium tuberculosis with a MIC of 25 mg/mL.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.316.1-316.1
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• 2002

Dermatan sulfate (DS) was isolated from eel skin (Anguilla japonica) bv actinase and endonuclease digeslions followed by ${\beta}$-elimination reaction and DEAE-Sephacel chromatography. DS was a major glycosaminoglycan in eel skin with 88% of the total uronic acid. The content of IdoA2S$\alpha$1longrightarrow4GalNAc4S sequence in eel skin. which is known to be a binding site to heparin cofactor II. was two times higher than that of dermatan sulfate from porcine skin. The anti-lla activity of eel skin dermatan sulfate mediated through heparin cofactor ll(NCL) was 25 units/mg. whereas DS from porcine skin shows 23.2 units/mg. The average molecular weight was determined as 14 kDa by gel chromatography on a TSKgel G3000SWXL column. Based on H1 NMR spectroscopy. we suggest that 3-sulfated and/or 2.3-sulfated ldoA residues are present in the chain.

• Journal of the Korean Chemical Society
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• v.19 no.1
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• pp.3-10
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• 1975

The partial molal volumes and relative viscosities of tetraethylammonium chloride in a series of dimethyl sulfoxide (DMSO)-water mixtures were measured at $30^{\circ}C$. A maximum structuredness of solvent, that leads to a minimum viscosity A-coefficient and a maximum viscosity B-coefficient of the Jones-Dole equation(${\eta}_r=1+AC^{1/2}$ + BC), was found at 0.2${\sim}$0.3 mole fraction of DMSO. The solvent structure, that leads to a minimum partial molal volume due to the maximum electrostrictive effect of chloride ion and to a minimum viscosity B-coefficient, was found at 0.4${\sim}$0.5 mole fraction of DMSO. An approximate relationship between the limiting effective flowing volume, $V_e^{\circ}$, and the B-coefficient was found to be B = 2.5 $V_e^{\circ}$ in the Einstein equation.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.1
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• pp.11-18
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• 2022

In order to improve the accuracy of particle tracking prediction techniques near the Korean Strait, this study compared and analyzed a particle tracking model based on a seawater flow numerical model and a machine learning based on a particle tracking model using field observation data. The data used in the study were the surface drifter buoy movement trajectory data observed in the Korea Strait, prediction data by machine learning (linear regression, decision tree) using the tide and wind data from three observation stations (Gageo Island, Geoje Island, Gyoboncho), and prediciton data by numerical models (ROMS, MOHID). The above three data were compared through three error evaluation methods (Correlation Coefficient (CC), Root Mean Square Errors (RMSE), and Normalized Cumulative Lagrangian Separation (NCLS)). As a final result, the decision tree model had the best prediction accuracy in CC and RMSE, and the MOHID model had the best prediction results in NCLS.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.3
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• pp.72-81
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• 2022

Positions of five drifting buoys deployed on August 2020 near southwestern area of Jeju Island and numerically predicted velocities were used to develop five Artificial Intelligence-based models (AI models) for the prediction of particle tracks. Five AI models consisted of three machine learning models (Extra Trees, LightGBM, and Support Vector Machine) and two deep learning models (DNN and RBFN). To evaluate the prediction accuracy for six models, the predicted positions from five AI models and one numerical model were compared with the observed positions from five drifting buoys. Three skills (MAE, RMSE, and NCLS) for the five buoys and their averaged values were calculated. DNN model showed the best prediction accuracy in MAE, RMSE, and NCLS.

• Journal of agriculture & life science
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• v.44 no.3
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• pp.41-52
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• 2010

This study was conducted to estimate genetic parameters for growth traits using multivariate animal models in Yorkshire breed. For the study, 16,202 records for growth traits collected between the year 1999 and 2005 from Yorkshire pigs in K GGP were used. The effects of environmental factors such as sex, birth year, birth season, parity and birth weight group affected growth traits significantly (p<0.01). Birth weight tended to be positively correlated with average daily gain (ADG) and lean percent. But it seemed to affect age at 90 kg, average adjusted backfat thickness (BF), and eye muscle ares (EMA) negatively. For average pig suckling weight (ASW) and total weight at suckling (TWS), the higher birth weight is the better performance. But, in case of total number of born and number of suckling, the result was shown vice versa. Approximately 10~30% lower heritability estimates were obtained for growth traits by using the model that includes descriptions of common litter effects (CL) than by using the model that ignores those (NCL) for more accurate estimation of heritability. The estimates of heritabilities were 0.468, and 0.328 for ADG, 0.474 and 0.326 for age at 90 kg, 0.452, and 0.396 for BF, 0.240 and 0.200 for EMA and, 0.458, and 0.380 for lean percent in NCL and CL, respectively. Therefore, in order to estimate optimal genetic parameters, it could be inferred that the statistical model which considers litter effects must be applied.

• Journal of the Korean Chemical Society
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• v.20 no.3
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• pp.185-192
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• 1976

Equivalent conductances of ammonium salts such as $NH_4Cl,\;CH_3NH_3Cl,\;(CH_3)_2NH_2Cl,\;(CH_3)_3NHCl\;and\;(CH_3)_4NCl$ have been measured in methanol-water mixtures of various composition (0.0${\sim}$0.6-mole frcation: m. f.) in the concentration range from 0.01 to 0.04 M at $25^{\circ}C$, and limiting equivalent conductances (${\Lambda}_0$) are determined by the analysis of Fuoss Onsager's semiempirical equation.The experimental results are discussed in terms of varing the size of ${\Lambda}_0$ due to the salts species and solvent composition. It has been observed in quite common over all salts that ${\Lambda}_0$ decreases with the increase of m. f. methanol, and the maximum decrement in ${\Lambda}_0$ shows between water and 0.1 m. f., while the plot of ${\Lambda}_0$ vs. m. f. goes through a minimum at 0.4 m. f. and then turns slightly upward. On the other hand, the ${\Lambda}_0$ decrease with the increase of the size of ammonium cation and the larger values ${\Lambda}_0$ are showed in comparison with those of values observed for the corresponding $n-RNH_3Cl$ under the same experimental procedure. All these behaviors are considered to be closely correlated with the structures of solvents and solutes and the significant similarities are compared with the behaviors of partial molar volumes for amine salts in same solvent system.