• The Journal of Korean Academy of Prosthodontics
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• v.43 no.5
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• pp.684-693
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• 2005

Statement of problem: Ti-6Al-7Nb alloy is used instead of Ti-6Al-4V alloy that was known to have toxicity. Purpose: This study was performed to investigate the effect of electrolyte concentration on the surface characteristics of anodized and hydrothermally-treated Ti-6Al-7Nb alloy Materials and methods: Discs of Ti-6Al-7Nb alloy of 20 mm in diameter and 2 mm in thickness were polished sequentially from #300 to 1,000 SiC paper ultrasonically washed with acetone and distilled water for 5 min, and dried in an oven at $50^{\circ}C$ for 24 hours. Anodizing was performed at current density $30mA/cm^2$ up to 300 V in electrolyte solutions containing $\beta-glycerophosphate$ disodium salt hydrate $(\beta-GP)$ and calcium acetate (CA). Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. All samples were soaked in the Hanks' solution with pH 7.4 at $36.5^{\circ}C$ for 30 days. Results and conclusion: The results obtained were summarized as follows: 1. After hydrothermal treatment, the precipitated HA crystals showed the dense fine needle shape. However, with increasing the concentration of electrolyte they showed the shape of thick and short rod. 2. When the dense fine needle shape crystals was appeared after hydrothermal treatment, the precipitation of HA crystals in Hanks' solution was highly accelerated. 3. The crystal structures of $TiO_2$ in anodic oxide film were composed of strong anatase peak and weak rutile peak as analyzed with thin-film X-ray diffractometery. 4. The Ca/P ratio of the precipitated HA layer was equivalent to that of HA crystal in Hanks' solution.

• Restorative Dentistry and Endodontics
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• v.26 no.4
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• pp.316-325
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• 2001

The purpose of this study was to evaluate the effect of adhesive curing timing on the direction of polymerization shrinkage of light-curing composite resin. In this study, the curing times of adhesive and composite resin were measured by differential scanning calorimeter(DSC). 28 extracted human molars were embedded in clear resin and box-type cavities were prepared. Based on DSC data, the experimental teeth were divided into 4 groups. Group 1: no bond; Group 2: late curing; Group 3: Intermediate curing; Group 4: Early curing. After treating with adhesive, the buccal cavities were filled with Z-100 hybrid composite resin and the lingual ones were filled with AEliteflo flowable composite resin. The depressions at the surface were measured by surface profilometer, then the specimens were embedded in clear resin and sectioned. Impressions were obtained and used to get epoxy resin replicas. The epoxy replicas were gold-coated and observed under SEM. Average Maximum Gap(AMG), Gap Proportion(GP), Average Marginal Index(AMI) were used to compare the shrinkage gap of each group. The results were statistically analyzed using the Kruskal-Wallis One Way ANOVA, Student-Newman-Keuls method. The results of this study were as follows. 1. Average Maximum Gap, Gap Proportion, Average Marginal Index and depression at the surface or Z-100 hybride composite resin were smaller than those of AEliteflo flowable composite resin(P<0.05). 2. When the bonding between composite resin and tooth structure was strong, the shrinkage gap was small, and depression at the surface was deep(P<0.05). 3. In the well-bonded group, light-curing composite resin shrank toward bonded cavity wall, not toward light source. The result suggested that the direction of polymerization shrinkage was affected by the quality of bonding in the dentin-resin interface. The strong was the bonding between composite resin and tooth structure, the smaller was the gap and the deeper was the depression at the surface. Then the flow to compensate the polymerization shrinkage proceeded from surface to bonded cavity wall.

• Journal of the Korean Chemical Society
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• v.41 no.2
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• pp.77-81
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• 1997

The transport rates of transition metal cations were increased in order of Ni(II)$(NtnOenH_4)$and 1,12,15-triaza-3,4;9,10-dibenzo-5,8-dioxacyclo-heptadecane$(NdienOenH_4)$as carriers. The transport rates of transition metal cations was found to be of first order to the salt concentrations. It was also found that the dissociation process in the transport process is rate determining step. From the measurements of the transport rates at various temperatures, the partition free energies of hydration$({\Delta}G_p)$for the transition metal cations were calculated. The results showed that the order of transport rates of transition metal cations was found to be proportional to the magnitudes of negative value of the partition free energies of hydration$({\Delta}G_p)$.

• The Korean Journal of Mycology
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• v.12 no.4
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• pp.141-152
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• 1984

Aspergillus niger van Tieghem was cultured by the method of synchronous and submerged culture. Throughout the culture, sporulation was occured. Highly phosphorylated nucleotides in sporulating mycelia were detected to assure whether the eucaryotic Aspergillus niger produce these substances or not during the differentiation. Phosphorylated nucleotides were extracted from the conidiophore, bearing mycelia and spore forming body, these nucleotides were identified by TLC with P.E.I. cellulose. Guanosine tetraphosphate was found in both phialide forming mycelia and spore forming body. The contents of free amino acids were assayed and its level was found to increase at early stage of sporulation. The effects of 8-azaguanine examined, it was found to prevent spore formation and to made abnormal structure. The effects of inosinic monophosphate and guanosine monophosphate on spore formation were examined, spore formation was enhanced by these nucleotides.

• The Korean Journal of Physiology and Pharmacology
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• v.26 no.3
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• pp.145-155
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• 2022

Multidrug resistance of tumors has been a severe obstacle to the success of cancer chemotherapy. The study wants to investigate the reversal effects of imperatorin (IMP) on doxorubicin (DOX) resistance in K562/DOX leukemia cells, A2780/Taxol cells and in NOD/SCID mice, to explore the possible molecular mechanisms. K562/DOX and A2780/Taxol cells were treated with various concentrations of DOX and Taol with or without different concentrations of IMP, respectively. K562/DOX xenograft model was used to assess anti-tumor effect of IMP combined with DOX. MTT assay, Rhodamine 123 efflux assay, RT-PCR, and Western blot analysis were determined in vivo and in vitro. Results showed that IMP significantly enhanced the cytotoxicity of DOX and Taxol toward corresponding resistance cells. In vivo results illustrated both the tumor volume and tumor weight were significantly decreased after 2-week treatment with IMP combined with DOX compared to the DOX alone group. Western blotting and RT-PCR analyses indicated that IMP downregulated the expression of P-gp in K562/DOX xenograft tumors in NOD/SCID mice. We also evaluated glycolysis and glutamine metabolism in K562/DOX cells by measuring glucose consumption and lactate production. The results revealed that IMP could significantly reduce the glucose consumption and lactate production of K562/DOX cells. Furthermore, IMP could also remarkably repress the glutamine consumption, α-KG and ATP production of K562/DOX cells. Thus, IMP may sensitize K562/DOX cells to DOX and enhance the antitumor effect of DOX in K562/DOX xenograft tumors in NOD/SCID mice. IMP may be an adjuvant therapy to mitigate the multidrug resistance in leukemia chemotherapy.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.3
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• pp.91-100
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• 1999

To extract value-added products from satellite images for the benefit of science and human life, the Satellite Technology Research Center at Korea Advanced Institute of Science and Technology has developed an integrated software 'Valadd-Pro'. In this paper, the 'Valadd-Pro' software is briefly introduced and its main components such as geometric correction, ortho correction and digital elevation model extraction are described. The performances of the 'Valadd-Pro' was assessed on $60km{\times}60km$ SPOT panchromatic images using ground control points from GPS measurements. Also, the height accuracy was measured by comparing our results with the $DTEDs^3$ produced by USGS and the DEM generated from the digitized countours of maps produced by the National Geographic Institute. In geometric correction, the 'Valadd-Pro' software needed fewer ground control points than a commercial software 'P' for the satisfactory results. In ortho correction, the 'Valadd-Pro' software show the similar performance to a commercial software 'P'. In digital elevation model extraction, the 'Valadd-Pro' software is two times more accurate and four times faster than a commercial software 'P'.

• Journal of Ginseng Research
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• v.23 no.3 s.55
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• pp.182-189
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• 1999

For the determination of anti oxidative effects of Korean red ginseng extracts, 100 mg/kg body weight of paraquat(1,1-dimethyl-4,4-bipyrimidinium dichloride) was injected to peritoneal cavity of 6 weeks 23-27 g of ICR mail mice which were pretreated with 200 mg/kg body weight of korean red ginseng extracts(total saponin, water extracts, alcohol extracts, lipophilic extracts) and ascorbic acid for 5 days. Most of mice died of paraquat toxicity within 4 days except only $30\%$ of ascorbic acid group. The hepatic total-SOD activity in liver was highest in ascorbic acid group and lipophilic ginseng extracts group next (p<0.0l). The level of hepatic hydroperoxide was lowest in the order of in alcohol extracts group, lipophilic extracts group and ascorbic acid group (p<0.0l). The highest catalase activity was induced by ascorbic acid followed by water extracts and lipophillic extracts (p<0.01). Finally, the lipid peroxidation level (malondialdehyde:MDA) was the lowest in water extracts group and ascorbic acid next (p<0.01). The highest MDA level was appeared in praquat group and next total saponin group next. In conclusion, the order of effectiveness of antioxidants was found to be ginseng water extracts> ascorbic acid> lipophillic extracts> other ginseng extracts. It was also found that any predominant antioxidant was not effective evenly to all of antioxidant test.

• Journal of the korean academy of Pediatric Dentistry
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• v.49 no.2
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• pp.197-205
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• 2022

This study was conducted to investigate the fluoride release of fluoride-containing restorative materials in fluoride recharging according to the concentration of fluoride toothpaste used in Korea. Samples of glass ionomer cement, resin-modified glass ionomer cement, alkasite restorative material, and composite resin were prepared and fluoride release was measured on days 1, 3, 7, 14, 21, 28. Thereafter, fluoride-free, 500 ppm, and 1450 ppm fluoride toothpaste was applied to each restorative materials, and the fluoride release was measured on days 1, 3, 7. Glass ionomer cement showed the highest cumulative fluoride release until the 7th day of measurement, and from the 14th day onwards, the resin-modified glass ionomer cement showed the highest cumulative fluoride release, but there was no significant difference. When restorative material groups were recharged with 500 ppm of fluoride toothpaste, the fluoride release was significantly higher only for the alkasite restorative material compared to the fluoride-free toothpaste group (p < 0.017). When restorative material groups were recharged with 1450 ppm of fluoride toothpaste, the fluoride release was significantly higher in all restorative groups compared to the fluoride-free toothpaste group (p < 0.017).

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.8
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• pp.3773-3778
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• 2014

Background: The study was aimed to evaluate the prevalence and genotype distribution of HPV infection in vulvar squamous cell carcinoma (SCC) in northern Thailand and the clinicopathological difference with regard to HPV infection status. Materials and Methods: Formalin-fixed paraffin-embedded tissue samples of vulvar SCC diagnosed between January 2006 and December 2012 were collected. HPV infection was detected by nested polymerase chain reaction (PCR) with primers MY09/11 and GP5+/6+. HPV genotyping was performed using the Linear Array Genotyping Test, followed by type-specific PCR targeting the E6/E7 region of HPV16/18/52 if the Linear Array test was negative. The histologic slides of vulvar lesions and the medical records were reviewed. Results: There were 47 cases of vulvar SCC included in the study (mean patient age $57.9{\pm}13.2$ years). HPV infection was detected in 29 cases (62%), all of which had single HPV infections. HPV16 accounted for 23 (49%). The patients with HPV-positive SCC had a significantly younger mean age than those with HPV-negative tumors (52.7 years vs 66.2 years, p<0.001). There was no significant difference in tumor stage distribution with regard to the status of HPV infection. The presence of vulvar intraepithelial neoplasia (VIN) of usual type (basaloid or warty) was significantly more frequent in HPV-positive cases compared with HPV-negative cases (62% vs 6%, p<0.001), whereas differentiated-type VIN was more common in HPV-negative cases (24% vs 0%, p=0.019). Conclusions: HPV infection was detected in 62% of vulvar SCC in northern Thailand. HPV16 was the predominant genotype similar to the data reported from other regions. HPV-positive SCC occurred in younger patients compared with HPV-negative SCC, and was associated with usual-type VIN. Vaccination against HPV16/18 may potentially prevent almost one half of vulvar SCC in northern Thailand.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.1
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• pp.13-22
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• 2017

Objectives: The objective of this study was to evaluate the exposure levels of door-to-door deliverers to fine particulate matter (PM2.5). Another objective was to confirm the general working patterns of door-to-door deliverers via survey. Methods: In the city of Daegu, ten door-to-door deliverers who wished to join the study were recruited. The general working characteristics of door-to-door deliverers were surveyed using self-reported questionnaires. In the cabin of each car driven by a deliverer, a real-time PM2.5 sampler (Sidepak, Model AM510, TSI Inc., MN, USA) and a GPS device (GPS 741, Ascen, Korea) were installed. Each deliverer was monitored for four days per week so that each day could be monitored at least four times. Results: A total of 40 measurements of PM2.5 concentrations were taken during delivery of parcels. The average exposure levels of door-to-door deliverers to PM2.5 was $44.62{\mu}g/m^3$ ($7-9443{\mu}g/m^3$. Exposure levels to PM2.5 according to the day of the week and coverage areas were not significantly different (p>0.05). Door-to-door deliverers using trucks with older diesel engines manufactured before 2006 had significantly higher exposure levels to PM2.5 than in the case of trucks with diesel engines manufactured after 2006 (p<0.05). Many of the door-to-door deliverers reported the status of having windows open during the delivery task. During delivery services, the working hours spent in residential areas were higher than on roadsides, but exposure levels to PM2.5 in residential areas and on roadsides were $46.17{\mu}g/m^3$ and $49.90{\mu}g/m^3$, respectively. Real-time PM2.5 exposure levels were significantly different between roadways and residential areas (p<0.001). Conclusions: PM2.5 exposure levels of door-to-door deliverers were found to be affected by higher vehicle emissions from the roadsides near their vehicle during deliveries and while driving to other locations compared to by PM2.5 from the diesel engines of their own trucks. Particle concentrations from roadsides and emissions from nearby vehicles through open windows were the main source of PM2.5.