• Bulletin of the Korean Chemical Society
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• v.13 no.4
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• pp.375-381
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• 1992

In this study we have synthesized two spiro orthocarbonates, which can be polymerized with volume expansion, and determined their crystal structures. The crystal data are as follows; 3,4,10,11-Di(9,10-dihydro-9,10-ethanoanthracenyl)- 1,6,8,13-tetraoxa-6.6-tridecane 5: a = 16.898 (1), b = 9.299 (1), c = 24.359 (2) ${\AA}$, $\beta$ = 123.73 $(7)^{\circ}$, space group P21/c and R = 0.073 for 2954 reflections; compound 8: a = 15.244 (4), b = 15.293 (3), c = 10.772 (3) $\AA$, ${\beta}$ = 99.45 $(2)^{\circ}$, space group P21/c and R = 0.082 for 2346 reflections. The seven-membered rings of compound 5 are chair forms and all the six-membered rings are boat shaped. For a six-membered spiro orthocarbonate, 3,9-Di(9-fluorenylidenyl)-1,4,6,9-tetraoxa-5,5-und ecane 8, fluorene groups [C(1) atom through C(13) atom] are planar within ${\pm}0.09{\AA}$ and the six-membered rings have chair conformations. The whole molecule has pseudo-C2 symmetry. The water molecules in the crystal are linked with each other through the hydrogen bond with distance of 2.790 (20) ${\AA}$.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.261-264
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• 2008

• Journal of the Korean Ceramic Society
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• v.39 no.11
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• pp.1069-1073
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• 2002

Properties of $B_4C/Al$ cermets were studied as a function of atmosphere during infiltration and post-heat treatment. The cermet A(infiltrated at $1100{\circ}C$/10 min under vacuum) had 19.4 wt% of Al but the cermet B(infiltratd at $1080{\circ}C$/10 min under a flowing argon) showed 14.4 wt% of Al. It indicated that the reaction between $B_4C$ and Al underwent slower under vacuum than under a flowing argon. The cermet B as infiltrated showed the density of 2.65 $g/cm^3$, the MOR of 503 MPa and the Young's Modulus of 237 GPa, but the post-heat treatment at $900{\circ}C$ for 8h under a flowing Ar gave rise to the cermet with the density of 2.65 $g/cm^3$, the MOR of 296 MPa, the Young's Modulus of 300 GPa. The cermet B showed better properties than the cermet A. Changes in compositions of the cermets by the post-heat treatment were observed qualitatively by XRD and SEM, the amount of Al was determined by analysis of its DSC curve.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.234-240
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• 2013

The synthesis of title compounds were accomplished by synthetic sequence shown in Scheme 1. Chalcones on cyclocondensation with thiourea in ethanol and potassium hydroxide under reflux yielded the respective dihydropyramidin-2(1H)-thiones. Each of the dihydropyrimidin thiones was, then subjected to the Mannich condensation in alkaline medium using three different secondary amines, viz., dimethylamine, diethylamine and morpholine to obtain a new series of S-Mannich bases. All the synthesised compounds ($C_1-C_{15}$) were evaluated for their antiulcer and antibacterial activities. Compounds $C_4$, $C_5$, $C_6$, $C_{14}$ and $C_{15}$ exhibited relatively more potent antiulcer activity but not comparable to the standard; Omeprazole, while $C_1$, $C_2$, $C_3$ and $C_{13}$ were moderate in activity at 100 mg/kg p.o. All the compounds ($C_1-C_{15}$) showed mild to moderate activity against both Gram-positive (S.aureus, L.delbrueckii) and Gram-negative (P.vulgaris, E.coli) bacteria. Amongst the compounds tested, only $C_6$, $C_9$, $C_{12}$ and $C_{15}$ were found to be potent.

• Korean Journal of Food Science and Technology
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• v.27 no.4
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• pp.506-515
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• 1995

The cultural characteristics of 60 strains of psychrotrophic lactic acid bacteria which were isolated from kimchi, a Korean traditional fermented vegetable food, and identified as Leuconostoc mesenteroides subsp. mesenteroides, Leu. mesenteroides subsp. dextranicum, Leu. paramesenteroides, Leu. lactis, Lactobacillus bavaricus and Lac. homohiochii were tested. All strains grew at $5^{\circ}C,\;10^{\circ}C\;and\;37^{\circ}C$ in tomato glucose broth, but not at $45^{\circ}C$. The optimum growth temperature of Leu. mesenteroides and Lactobacillus sp. were $33{\sim}34^{\circ}C\;and\;34{\sim}36^{\circ}C$, respectively. All strains of Leu. mesenteroides and Lactobacillus sp. grew at 4.8 and 4.2 of initial pH, but not at 4.0. The final pH of Leu. mesenteroides and Lactobacillus sp. in glucose broth were $3.84{\sim}4.10\;and\;3.82{\sim}3.99$, respectively. None of the 60 strains clotted milk nor reduced litmus in litmus milk. All strains of Leu. mesenteroides and Lactobacillus sp. grew in tomato glucose broth containing 7% ethanol or 6.5% NaCl, but not in the broth containing 15% ethanol or 10% NaCl. All strains grew in tomato glucose broth containing 40% bile juice and survived in the artificial gastric juice of pH 3.5. Furthermore, all strains of Leu. mesenteroides survived in the artificial gastric juice of pH 3.0. Since many strains of lactic acid bacteria tested in this study showed differences in several physiological characteristics from those described in Bergey's Manual of Systematic Bacteriology, it was considered that further tests would be necessary to clarify their positions in taxonomic system.

• Microbiology and Biotechnology Letters
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• v.48 no.4
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• pp.547-555
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• 2020

Microalgae are a promising resource in energy and food production as they are cost-effective for biomass production and accumulate valuable biological resources. In this study, CO2 assimilation, biomass, and lipid production of 4 microalgal species (Chlorella vulgaris, Mychonastes homosphaera, Coelastrella sp., and Coelastrella vacuolata) were characterized at different CO2 concentrations ranging from 1% to 9%. Microscopic observation indicated that C. vulgaris was the smallest, followed by M. homosphaera, C. vacuolata, and Coelastrella sp. in order of size. C. vulgaris grew and consumed CO2 more rapidly than any other species. C. vulgaris exhibited a linear increase in CO2 assimilation (up to 9.62 mmol·day-1·l-1) as initial biomass increased, while the others did not (up to about 3 mmol·day-1·l-1). C. vulgaris, Coelastrella sp., and C. vacuolata showed a linear increase in the specific CO2 assimilation rate with CO2 concentration, whereas M. homosphaera did not. Moreover, C. vulgaris had a greater CO2 assimilation rate compared to those of the other species (14.6 vs. ≤ 11.9 mmol·day-1·l-1). Nile-red lipid analysis showed that lipid production per volume increased linearly with CO2 concentration in all species. However, C. vulgaris increased lipid production to 18 mg·l-1, compared to the 12 mg·l-1 produced by the other species. Thus, C. vulgaris exhibited higher biomass and lipid production rates with greater CO2 assimilation capacity than any other species.

• Journal of the Korean Chemical Society
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• v.38 no.4
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• pp.283-287
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• 1994

The crystal stucture of bithional surfoxide, $C_{12}H_6Cl_4O_3S$, has been determined from 2295 independent reflections collected on an automated CAD-4 diffractometer with a graphite-monochromated $Mo-K\alpha$ radiation. The crystal belongs to the monoclinic, space group P2$_1$/n, with a unit cell dimensions a = 12.448(4), b = 9.740(1), c = $11.815(2)\AA$, $\beta$ = $100.06^{\circ}$, $\mu$ = 9.02 cm$^{-1}$, Dm = 1.76 g/cm$^3$, Dc = 1.75 g/cm$^3$, F(000) = 744, and Z = 4. The structure was solved by the direct method and refined by the least-squares method. The final R values was 0.037 for 2295 independent reflections. Overall conformation of the molecule is folded with respect to central surfur atom. Comparing with the molecular conformation of bithional, one of phenyl rings was swinged with about $180^{\circ}.$ This conformational change in the molecule results in the existance of intramolecular-hydrogen bond of S-O(3)---H-O(1) type and its steric hindrance between this moiety and the other phenyl ring. The two best planes of the phenyl rings have a maximum deviation of 0.009 $\AA$ for C(1) atom. The dihedral angle between two phenyl rings is $99.22^{\circ}.$ In the crystal structure, the molecules are packed with intermolecular-hydrogen bond of O(3)---H-O(2).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.255-259
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• 1983

This work was done in order to clarify the chemical characteristics, composition, fatty acid components and sterol components of the lipids from Urechis unicintus. The results obtained are summarized as follows ; 1. The lipid content, iodine value and unsaponifiable matter of the total lipids are 1.89, 111, and $14.3\%$, respectively. 2. The main components of the total lipids are phospholipids $39.8\%$, free sterol $27.7\%$ and triglyceride $21.4\%$, and two unidentified fractions are detected. 3. The main fatty acids of total lipids are $C_{20:4}(19.4\%),\;C_{16:0}(13.7\%),\;C_{20:1}(11.3\%)\;and\;C_{18:1}(10.4\%)$ 4. Sterols found are Cholesterol($57.6\%$), Brassicasterol(?)($20.3\%$), 24-methylenecholesterol ($17.7\%$),22-dehydrocholesterol($3.0\%$)and 22.trans-24-norcholesta-5,22-dien-$3{\beta}$-ol(?)$1.4\%$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.63-65
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• 2021

This paper describes an integrated H/W-S/W implementation of elliptic curve digital signature algorithm (EC-DSA) using a security system-on-chip (SoC). The security SoC uses the Cortex-A53 APU as CPU, and the hardware IPs of high-performance elliptic curve cryptography (HP-ECC) core and SHA3 (secure hash algorithm 3) hash function core are interfaced via AXI4-Lite bus protocol. The signature generation and verification processes of EC-DSA were verified by the implementation of the security SoC on a Zynq UltraScale+ MPSoC device.

• Bulletin of the Korean Chemical Society
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• v.23 no.12
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• pp.1715-1718
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• 2002

Treatment of ethyl 5-hydroxy-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxylate (1a) with hydrazine hydrate in ethanol gave the carbohydrazide 2,. Some derivatives of the latter compound have been synthesized. Also, 6-acetyl-3,4-diphenyl-5-hydroxythieno[2.3-c]pyridazine (1b) was subjected to some reactions to produce other new thienopyridazine derivatives.