• Restorative Dentistry and Endodontics
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• v.17 no.1
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• pp.83-94
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• 1992

This study was executed to measure the biosynthesis of arachidonic acid metabolic products in chronic periapical lesions, to compare the products among periapical granuloma, periapical cyst and chronic periapical abscess, and to understand the pathogensis of chronic periapical lesions. Tissues from 33 chronic periapical lesions of human teeth were enucleated during endodontic surgery. large part of each tissue was contained in liquid nitrogen immediately and the other was examined histologically. In histologically diagnosed 8 cases of periapical granuloma, 9 cases of periapical cyst and 8 cases of chronic periapical abscess. the tissues were homogenatecl and incubated with $_{14}C$-arachidonic acid. Lipid solvent extracts were separated by thin layer chromatography to be analyzed by autoradiography and TLC analyzer. 1. $TXB_2$, 6-keto-$PGF_1{\alpha}$ and $PGE_2$, $LTB_4$, HETEs, and unidentified product which are metabolic products of arachidonic acid were measured in the tissues of chronic peripaical lesions. 2. In all of periapical granuloma, cyst and abscess, the conversion rate of HETEs among all products was the highest(P<0.05), and the percentage of HETEs in total converted products was also the highest(P<0.05). 3. The concentration of each arachidonic acid product was higher in chronic periapical absecss than in periapical granuloma and cyst(P<0.05). The concentration of $TXB_2$ and HETEs in periapical cyst were hight than in periapical granuloma. 4. The relative amounts of total products from lipoxygenase pathway to those from cyclo-oxygenase pathway were about 7 fold in chronic periapical lesions. There was no difference among periapical granuloma, cyst and abscess(P<0.05). The total amount of products from each pathway were higher in chronic periapical abscess than in periapical cyst and granuloma.

• Progress in Superconductivity
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• v.14 no.1
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• pp.1-10
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• 2012

We fabricated a closed coils by using resistive-joint method and the joint resistance of the coils were estimated by field decay technique in liquid nitrogen. We used the Runge-kutta method for the numerical analysis to calculate the decay properties. The closed coil was wound by $(Bi,Pb)_2Sr_2Ca_2Cu_3O_x$/Ag tape. Both ends the tape were overlapped and soldered to each other. The current was induced in a closed coils by external magnetic flux density. Its decay characteristic was observed by means of measuring the magnetic flux density generated by induced current at the center of the closed coil with hall sensor. The joint resistance was calculated as the ratio of the inductance of the loop to the time constants. The joint resistances were evaluated as a function of critical current of loop, contact length, sweep time, and external magnetic flux density in a contact length of 7 cm. It was observed that joint resistance was dependent on contact length of a closed coil, but independent of critical current, sweep time, and external magnetic flux density. The joint resistance was measured to be higher for a standard four-probe method, compared with that for the field decay technique. This implies that noise of measurement in a standard four-probe method is larger than that of field decay technique. It was estimated that joint resistance was $8.0{\times}10^{-9}{\Omega}$ to $11.4{\times}10^{-9}{\Omega}$ for coils of contact length for 7 cm. It was found that 40Pb/60Sn solder are unsuitable for persistent mode.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.5
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• pp.72-79
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• 2000

On the other hand, the fiber orientation at the surface and middle layer of the sheet controls the bending stiffness of paperboard. Therefore, a reliable measurement of paper surface fiber orientation gives us a magnificent tool to investigate and predict paper curling and cockling tendency, and provides the necessary information to fine-tune the manufacturing process for optimum quality. Many papers, especially heavily calendered and coated grades, do resist liquid and gas penetration very much, being beyond the measurement range of the traditional instruments or resulting inconveniently long measuring time per sample. The increased surface hardness and use of filler minerals and mechanical pulp make a reliable, non-leaking sample contact to the measurement head a challenge of its own. Paper surface coating causes, as expected, a layer which has completely different permeability characteristics compared to the other layers of the sheet. The latest developments in sensor technologies have made it possible to reliably measure gas flow n well controlled conditions, allowing us to investigate the gas penetration of open structures, such as cigarette paper, tissue or sack paper, and in the low permeability range analyze even fully greaseproof papers, silicon papers, heavily coated papers and boards or even detect defects in barrier coatings! Even nitrogen or helium may be used as the gas, giving us completely new possibilities to rank the products or to find correlation to critical process or converting parameters. All the modern paper machines include many on-line measuring instruments which are used to give the necessary information for automatic process control systems. Hence, the reliability of this information obtained from different sensors is vital for good optimizing and process stability. If any of these on-line sensors do not operate perfectly as planned (having even small measurement error or malfunction), the process control will set the machine to operate away from the optimum, resulting loss of profit or eventual problems in quality or runnability. To assure optimum operation of the paper machines, a novel quality assurance policy for the on-line measurements has been developed, including control procedures utilizing traceable, accredited standards for the best reliability and performance.

• Membrane Journal
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• v.8 no.2
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• pp.86-93
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• 1998

A permeation apparatus has been devdoped which could make the on-line measurements of both flux and permeate composition. Pervaporative experiment of a single component, i.e. water was performed by using poly(vinyl alcohol) membrane crosslinked with glutaraldehyde to confirm the validity of the apparatus. In the experiment, steady-state permeation was obtained in 15 minutes and the measurement could be completed within 20 minutes. A comparison of the on-line measurement was made with the fluxes measured simultaneously by the conventional method in which the permeates were collected by liquid nitrogen. The on-line measurement by the apparatus showed an excellent agreement with the conventional measurement within a difference of $\pm$2%. From the flux data with operating time, 3 kinds of diffusion coefficients of water $D_{slope}, D_{1/2}$, and $D_t$ were determined, which were also coincident with values in a literature. It was confirmed that accurate measurements of fluxes could be obtained from the apparatus.

• Journal of Welding and Joining
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• v.27 no.6
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• pp.74-79
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• 2009

Titanium and titanium alloy can be reproduced immediately even if oxide films($TiO_2$) break apart in sea water. Therefore, since titanium demonstrates large specific strength and outstanding resistance to stress corrosion cracking, crevice corrosion, pitting and microbiologically influenced corrosion in sea water environment, it has been widely applied to heat exchanger for ships. In particular, with excellent elongation, pure titanium may be deemed as optimal material for production of heat exchanger plate which is used with wrinkles formed for efficient heat exchange. Conventional plate type heat exchanger prevented leakage of liquid through insertion of gasket between plates and mechanical tightening by bolts and nuts, but in high temperature and high pressure environment, gasket deterioration and leakage occur, so heat exchanger for LPG re-liquefaction device etc do not use gasket but weld heat exchanger plate for use. On the other hand, since welded plate cannot be separated, it is important to obtain high quality reliable welds. In addition, for better workability and production performance, lasers that can obtain weldment with large aspect ratio and demonstrate fast welding speed even in atmospheric condition not in vacuum condition are used in producing products. So far, 1st report and 2nd report compared and analyzed embrittlement degrees by bead colors of weldment through quantitative analysis of oxygen and nitrogen and measurement of hardness as fundamental experiment for the evaluation of titanium laser welding, and evaluated the welding performance and mechanical properties of butt welding. This study welded specimens in various conditions by using laser and GTA welding machine to apply edge welding to heat exchanger, and evaluated the mechanical strength through tensile stress test. As a result of tensile test, laser weldment demonstrated tensile strength 4 times higher than GTA welds, and porosity could be controlled by increasing and decreasing slope of laser power at overlap area.

• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.462-467
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• 2006

An improvement of nitrogen and phosphorus removal in SBR using the elutriated acids from the food waste as an external carbon source was investigated in this study. The food waste was elutriated at $35^{\circ}C$ and pH 9 to produce the external carbon source. The elutriate of food waste were continuously collected. The elutriated liquid contained VFAs of 39,180 mg/L representing soluble COD of 44,700 mg/L. The SBR showed poor denitrification and EBPR (enhanced biological phosphorus removal) without elutriated VFAs addition. An average denitrification rate was 0.4 mg NOx-N/g MLVSS/day. In turn, EBPR was also inhibited by this poor denitrification because the remaining nitrate in anaerobic phase resulting a poor denitrification. On the other hand, the denitrification in anoxic phase significantly improved with an elutriated VFAs addition. Nitrate removal was 82% while the denitrification rate was 2.9 mg NOx-N/g MLVSS/day with 18.4 mL/cycle of elutriated VFAs. With the enhanced denitrification, nitrate concentration in anaerobic phase could effectively be controlled to a very low level. The elimination of nitrate inhibition in anaerobic phase resulted enhancement of EBPR. The specific phosphate release rate was $1.9mg\;PO_4^{3-}-P/g\; MLVSS/day$ with less than 0.5 mg/L of $PO_4^{3-}-P$ concentration.

• Korean Journal of Materials Research
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• v.2 no.5
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• pp.320-329
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• 1992

In 2Y-TZP powders calcined at temperature range of 80$0^{\circ}C$0 to 150$0^{\circ}C$, the effect of stabilization and the transformability of tetragonal phase on the tetragonal to monoclinic transformation have been investigated. The transformability of tetragonal phase in calcined powders shows maximum at the calcination temperature of 130$0^{\circ}C$. This result is explained by a combined effect of the increase of particle size and of constrained force among the particles with increasing the calcination temperature. The amount of transformed monoclinic phase with calcination temperature after quenching in liquid nitrogen, stress induction and isothermal aging at 25$0^{\circ}C$is also explained by the transformability of tetragonal phase determined by the sum of particle size effect and constraint effect.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.193-201
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• 2000

Prostaglandins (PGs) and Leukotrienes (LTs) have been implicated in the genesis of pulpal and periapical inflammation. In this study, the relationships among $PGE_2$, 6-keto-PG $F_1{\alpha}$ (a stable metabolite of $PGI_2$) and $LTB_4$ concentrations in inflamed pulp and periapical lesions were discussed. Pulp tissue were obtained in routine endodontic treatment and periapical lesions in periapical surgery after clinical diagnoses were made. These specimens were divided into four groups as normal pulp group (Control group), acute pulpitis group, chronic pulpitis group, and periapical lesion group. Pulp tissue and periapical lesions were stored in liquid nitrogen. The concentration of $PGE_2$, $PGI_2$ and $LTB_4$ were measured with ELISA. The data were analyzed by one-way ANOVA. Significantly higher levels of $PGE_2$, 6-keto-PG $F_1{\alpha}$ a and $LTB_4$ were found in acute pulpitis group than chronic pulpitis group and periapical lesion group(p<0.05). Periapical lesion group showed significantly higher mean concentrations of $PGE_2$ and $LTB_4$ than chronic pulpitis group. In control and chronic pulpitis group, significant higher levels of $PGI_2$ than $PGE_2$ and $LTB_4$ were found. These results suggested that the high levels of $PGE_2$ and $LTB_4$ in periapical lesions may be due to rich endothelium., fibroblast and lymphocyte known as the main producers of $PGE_2$ and $LTB_4$. $PGI_2$ may be thought to one of the most abundant PGs in normal pulp tissue.

• Journal of Veterinary Clinics
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• v.36 no.5
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• pp.259-265
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• 2019

This study was designed to investigate the effects of alpha-glucosyl rutin (G-rutin) and its comparative effects with other antioxidants (glutathione: GSH, catalase: CATA and beta-mercaptoethanol : ${\beta}ME$) on dog sperm freezing. In the first experiment (E1), the spermatozoa were diluted in freezing extender supplemented with 0 (control), 0.001, 0.01, or 0.1% G-rutin and frozen using liquid nitrogen ($LN_2$). The progressive motility, reactive oxygen species (ROS) level and apoptosis of spermatozoa were assessed after sperm thawing at $37^{\circ}C$ for 25 sec. In the second experiment (E2), 0.1% G-rutin group was compared with 10 mM ${\beta}-ME$, $5{\mu}M$ GSH and $50{\mu}M$ CATA groups by assaying progressive motility, viability and gene expression of Bcl-2 and SMCP after sperm freezing and thawing. In E1, 0.1% G-rutin group showed higher (P < 0.05) post-thaw progressive motility and lower (P < 0.05) ROS levels. In E2, the expressions of SMCP in G-rutin group were higher (P < 0.05) than in CATA group while Bcl-2 expression of G-rutin group was higher (P < 0.05) than ${\beta}-ME$ and CATA groups. However, there were no significant differences in progressive motility and viability. Therefore, we suggest that G-rutin can be used as a potentially antioxidative supplement in dog sperm freezing extender on the basis of gene expression related to motility and apoptosis as well as ROS level.

• Journal of Adhesion and Interface
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• v.20 no.3
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• pp.102-109
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• 2019

The material constitution of multi-layered thin film coated on the PET base film was analyzed using ATR FT-IR and pyro GC/MS combination. The cross section of the film was acquired by cracking the film after dipping in liquid nitrogen and was observed using optical microscope. Total thickness of the coated film was $70{\mu}m$ and three layers were observed. Since each layers were too thin to analyze directly except the surface layer, analyzable area of each layers were exposed by using a proper solvent and were investigated using ATR FT-IR and pyro GC/MS. Results shows that three layers were commonly consisted of urethane-acrylate copolymers. Also, inorganic and/or metal inclusions detected by XPS and SEM-EDAX were exhibited by nano size $SiO_2$ particles in layer(1) and aluminum flakes in layer(2).