• Journal of the Korean Ceramic Society
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• v.27 no.8
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• pp.1055-1063
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• 1990

The early hydration characteristics of the system $C_3S-C_3A-C_4AF$ according to the clinker composition variations, in order to establish the mutual interactionof clinker minerals during the portland cement hydration, have been studied. The early hydration rate of $C_3S$ was greatly effected by the change of $C_3S/C_3A$ ratio. The lower the $C_3S/C_3A$ ratio was, the faster the apex reaching time and the rate of heat liberation of the 2nd exothermic peak originating from the formation of $Ca(OH)_2$ were. The effect of $C_3S/C_3A$ ration on the amounts of $Ca(OH)_2$ formation was decreased, in process of hydration time, but the effect of $C_3S$ content was increased.

• Journal of the korean academy of Pediatric Dentistry
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• v.34 no.1
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• pp.36-42
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• 2007

To compare the survival rate of periodontal ligament cells preserved in storage media with good availability at the time of an avulsion injury, periodontal ligament cells were incubated in ${\alpha}-MEM$ culture medium containing 10% FBS in condition of $37^{\circ}C$, 5% $CO_2$. These cells were then cultured in HBSS, ${\alpha}-MEM$, milk(S co., P. co.) and tap water at the temperature of 4, 25, $37^{\circ}C$ each in 60 min. The groups were measured by MTT assay. The results were as follows : 1. Among the storage media at $4^{\circ}C$, ${\alpha}-MEM$ and P-milk had the highest preserving ability of periodontal ligament cells, while that of HBSS S-milk and tap was low in order. 2. Among the storage media at $25^{\circ}C$, ${\alpha}-MEM$ had the highest preserving ability of periodontal ligament cells, while that of P-milk, HBSS, S-milk, tap water was low in order. 3. Among the storage media at $37^{\circ}C$, the preserving ability of periodontal ligament cells was very high in ${\alpha}-MEM$, P-milk, HBSS and S-milk, it's lowest in tap water. 4. The preserving ability of periodontal ligament cells in ${\alpha}-MEM$ was high at $4^{\circ}C$ and it's low in order of $25^{\circ}C$, $37^{\circ}C$, but in HBSS was high at $4^{\circ}C$ and it's low at $25^{\circ}C$, $37^{\circ}C$ 5. The preserving ability of periodontal ligament cells in S-milk and P-milk was high at $4^{\circ}C$, $25^{\circ}C$ and it s low at $37^{\circ}C$. In conclusion, HBSS is the storage medium of choice in an avulsion, but in this study it is preferable to choose milk at $4^{\circ}C$ for tooth since it is easy to get and affect cell viability.

• Journal of the Korean Ceramic Society
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• v.39 no.3
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• pp.321-326
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• 2002

ZnWO$_4$ nano-powders were successfully prepared by polymerized complex method using zinc nitrate and tungstic acid as starting materials. In order to investigate the thermal decomposition and crystallization process, the polymeric precursors were heat-treated at temperatures from 300 to 600$^{\circ}$C for 3 h, and the heat-treated powders were characterized by XRD and FTIR. The surface morphology of the heat-treated powders were observed using SEM and TEM. The crystallite size was measured by X-ray analysis. Crystallization of the ZnWO$_4$ powders were detected at 400$^{\circ}$C and entirely completed at a temperature of 600$^{\circ}$C. The particles heat-treated 400 and 500$^{\circ}$C showed primarily co-mixed morphology with spherical and silkworm-like forms, while the particles heat-treated at 600$^{\circ}$C showed more homogeneous morphology. The average crystalline size were 19.9∼24.nm showing an ordinary tendency to increase with the temperatures from 400 to 600$^{\circ}$C.

• Applied Chemistry for Engineering
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• v.22 no.5
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• pp.447-452
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• 2011

Depletion of petroleum increased the need of alternative energy and chemical resources. Biomass, a renewable resource, can be transformed to bioenergy and biomaterials, and the materials from biomass will ultimately substitute petroleum based energy and chemical compounds. In this perspective, production of C4-C6 compounds for bioenergy and biomaterials are described for understating of current research progress. n-Butanol and n-butyric acid, the major C4 compounds, are produced by Clostridium tyrobutyricum, Clostridium beijerinckii, and Clostridium acetobutylicum. n-Hexanoic acid, a typical C6 compound, is produced by Clostridium kluyveri and Megasphaera elsdenii. Reported maximum amount of n-butanol, n-butyric acid and n-hexanoic acid was 21, 55, and 19 g/L, respectively, and extraction of these C4-C6 compounds are induced increase production by those anaerobic bacteria. In addition, a new bacterium Clostridium sp. BS-1 produced 5 g/L of n-hexanoic acid using galactitol.

• Korean Journal of Pharmacognosy
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• v.16 no.4
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• pp.233-238
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• 1985

A number of sedative alkaloids were isolated from Sanjoin(酸棗仁), the seeds of Zizyphus vulgaris Lamark var. spinosus Bunge (Rhamnaceae) which is an important Chinese medicinal material used to treat insomnia and sometimes to treat sleepiness. Those compounds were designated as Sanjoinine-A, B, C, D, etc. depending on the order of increasing polarity. Sanjoinine-A, $C_{31}H_{42}N_4O_4$, $mp\;249^{\circ}$, $[{\alpha}]^{27}_D-316$, Sanjoinine-B, $C_{30}H_{40}N_4O_4$, $mp\;212{\sim}4^{\circ}$, Sanjoinene, $C_{29}H_{35}N_3O_4$, $mp\;281{\sim}2^{\circ}$, $[{\alpha}]^{22}_D-272$, Sanjoinine-D, $C_{32}H_{46}N_4O_5$, $mp\;256{\sim}8^{\circ}$, $[{\alpha}]^{22}_D-53.6$, Sanjoinine-F, $C_{31}H_{42}N_4O_5$, $mp\;228{\sim}9^{\circ}$, $[{\alpha}]^{22}_D-215$, and $Sanjoinine-G_1,\;C_{31}H_{44}N_4O_5,\;mp\;236{\sim}8^{\circ},\;[{\alpha}]^{22}_D-68.6$, were found as 14-membered cyclic peptide alkaloids, $Sanjoinine-G_2,\;C_{30}H_{42}N_4O_4,\;mp\;182^{\circ},\;[{\alpha}]^{22}_D-79.2$, as being open chain peptide alkaloid, and Sanjoinine-E, $C_{19}H_{21}NO_2$, $mp\;166^{\circ}$, $[{\alpha}]^{20}_D-146.2$, N-Methylasimilobine, $C_{18}H_{19}NO_2$, $mp\;193{\sim}5^{\circ}$, $[{\alpha}]^{20}_D-204$, Sanjoinine-Ia, $C_{18}H_{19}NO_2$, $mp\;155{\sim}7^{\circ}$, $[{\alpha}]^{20}_D-140$, Sanjoinine-Ib, $C_{19}H_{21}NO_4$, $mp\;184^{\circ}$, Sanjoinine-K, $C_{16}H_{19}NO_3$, $mp\;159{\sim}61^{\circ}$, $[{\alpha}]^{20}_D+35$, Caaverine, $C_{17}H_{17}NO_2$, $mp\;204^{\circ}$, $[{\alpha}]^{20}_D-80$, and Zizyphusine, $C_{20}H_{24}NO_4$, $mp\;214{\sim}6^{\circ}$, $[{\alpha}]^{20}_D+317$ as being aporphine alkaloids. The heat treatment of the cyclic peptide alkaloids produced their isomeric products which showed enhanced sedative activity. The chemical structure of the isomeric products will be discussed.

• Journal of IKEEE
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• v.18 no.4
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• pp.447-455
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• 2014

In this research, n-based 4H-MOS Capacitor was fabricated with PECVD (plasma enhanced chemical vapor deposition) process for improving SiC/$SiO_2$ interface properties known as main problem of 4H-SiC MOSFET. To overcome the problems of dry oxidation process such as lower growth rate, high interface trap density and low critical electric field of $SiO_2$, PECVD and NO annealing processes are used to MOS Capacitor fabrication. After fabrication, MOS Capacitor's interface properties were measured and evaluated by hi-lo C-V measure, I-V measure and SIMS. As a result of comparing the interface properties with the dry oxidation case, improved interface and oxide properties such as 20% reduced flatband voltage shift, 25% reduced effective oxide charge density, increased oxide breakdown field of 8MV/cm and best effective barrier height of 1.57eV, 69.05% reduced interface trap density in the range of 0.375~0.495eV under the conduction band are observed.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.12
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• pp.1944-1949
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• 2001

Four SiC-Si$_3$N$_4$ceramic cutting tools with different composition have been fabricated by hot-pressing. Correlations among the annealing time, the corresponding microstructure and the mechanical properties of resulting ceramics have been investigated. The fracture toughness and the grain size of both SiC and Si$_3$N$_4$in SiC-Si$_3$N$_4$composites increased with the annealing time. 1\`he hardness of SiC-Si$_3$N$_4$composites was relatively independent of the grain size and the sintered density. These ceramic cutting tools were tested under various cutting conditions and compared with the commercial Si$_3$N$_4$ceramic cutting tools. The experimental results were compared in terms of tool life and cutting force. The performance of SiC-Si$_3$N$_4$ceramic cutting tool shows the possibility to be a new ceramic tool.

• Korean Journal of Crystallography
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• v.13 no.3_4
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• pp.148-151
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• 2002

The molecular and crystal structure of metalaxyl C/sub15/H/sub21/NO₄, was determined by single crystal x-ray diffraction study. Crystallographic data for, title compound P2₁/c, a=7.849(4) Å, b=13.081(5) Å, c=15.100(3) Å, β=101.8(2)°, V= 1517.6(3) ų, Z=4. The molecular. Structure model was solved by direct method and refined by full-matrix least- squares. The final reliable factor, R, is 0.067 for 1694 independent reflections (F/sub o//sup 2/>4σ(F/sub o//sup 2/)). The molecular structure of title compound shows an intramolecular hydrogen bond: Cl2-Hl2A…O1.

• Korean Journal of Crystallography
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• v.8 no.2
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• pp.138-143
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• 1997

The crystal structure of isoimperatorin, f-[(3-methyl-2-butenyl)oxy]-7H-furo[3,2-g][1] benzopyran-7-one, has been determined from single crystal x-ray diffraction study; C16H14O4, Monoclinic, P21/c, a=8.865(1) Å, b=9.331(1) Å, c=16.156(1) Å, β=98.12(1)', V=1322.9(2) Å3, T=293(2)K, z=4, Cu Kα(λ=1.5418 Å). The structure was solved by direct method and refined by full-matrix least squares to a final R=5.72% for 1922 unique observed Fo>4o(F0) reflections and 182 parameters.

• Food Science of Animal Resources
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• v.27 no.2
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• pp.171-178
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• 2007

This study was conducted to investigate the effect of ageing temperature(0 and $4^{\circ}C$) and time(2, 7, 14, 21, 28, and 49 days) on the meat quality of longissimus muscle from Hanwoo steer. The pH, Warner-Bratzler shear force(WBSF), myofibrillar fragmentation index(MFI), cooking and purge loss, sensory, morphological changes, and amino acid composition were assessed. The pH of longissimus muscle increased significantly(p<0.05) for 21 days at $0^{\circ}C$ and 14 days at $4^{\circ}C$, but decreased thereafter. Longissimus muscle aged from 14 days to 28 days at $4^{\circ}C$ had a lower WBSF than longissimus muscle aged at $0^{\circ}C$(p<0.05). The WBSF of longissimus muscle decreased significantly(p<0.05) with ageing time. The MFI, cooking and purge loss, tenderness, and juiciness scores were higher for longissimus muscle aged at $4^{\circ}C$ than at $0^{\circ}C$. As ageing time increased, the MFI, cooking and purge loss, tenderness, juiciness, and amino acid composition of longissimus muscle increased significantly(p<0.05) with ageing at 0 or $4^{\circ}C$. Transmission electron microscopy showed Z-disk degradation and morphological changes of the myofibrils correlating with increased tenderness during the ageing time. Based on these results, the proper ageing conditions of longissimus muscle of Hanwoo steer were 14 days of ageing at $0^{\circ}C$ or 7 days of ageing at $4^{\circ}C$. However, further study on the application of ageing technology to this industry is necessary for the optimization of ageing conditions for the sub-primals or muscles from Hanwoo beef.