• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.189-196
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• 2020

PURPOSE. The aim of the present study was to investigate the effects of surface treatments on the bond strengths between polymer-containing restorative materials and two dual-cure resin cements. MATERIALS AND METHODS. In the present study, rectangular samples prepared from Lava Ultimate (LU) and Vita Enamic (VE) blocks were used. The specimen surfaces were treated using CoJet sandblasting, 50 ㎛ Al₂O₃ sandblasting, % 9 HF (hydrofluoric) acid, ER,Cr:YSGG laser treatment, and Z-Prime. Dual-cure resin cements (TheraCem and 3M RelyX U 200) were applied on each specimen's treated surface. A micro-tensile device was used to evaluate shear bond strength. Statistical analysis was performed using the SAS 9.4v3. RESULTS. While the bond strength using TheraCem with LU or VE was not statistically significant (P=.164), the bond strength using U200 with VE was statistically significant (P=.006). In the TheraCem applied VE groups, Z-Prime and HF acid were statistically different from CoJet, Laser, and Sandblast groups. In comparison of TheraCem used LU group, there was a statistically significant difference between HF acid and other surface treatments. CONCLUSION. The bonding performance between the restorative materials and cements were material type-dependent and surface treatment had a large effect on the bond strength. Within the limitations of the study, the use of both U200 and TheraCem may be suggested if Z-prime was applied to intaglio surfaces of VE. The cementation of LU using TheraCem is suitable after HF acid conditioning of the restoration surfaces.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.323-334
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• 1998

The purpose of this study was to compare the microleakage of the amalgam and the gallium alloy when several lining materials were applied. The ANA 2000, high copper lathecut type amalgam(AM group) and Gallium Alloy GF II (GF group) were used. The fifty extracted sound molars were randomly assigned to AM group and GF group, and the buccal and lingual class V cavities with a size $3{\times}2{\times}2mm$ were prepared. The prepared cavities were randomly assigned to group 1 : no liner used control, group 2 : Copalite, group 3 : Panavia 21, group 4 : All-bond 2, and group 5 : Superbond C&B. After liner placement and amalgam filling, the specimens were stored in $37^{\circ}C$ normal saline for 24 hours and then thermocycled from $5^{\circ}C$ to $55^{\circ}C$ thousand times. The specimens were stored in the 1% methylene blue solution for 24 hours and sectioned and examined by stereomicroscope. The results obtained from this study can be summarized as follows : 1. In the GF group, microleakage values of group 2, 3, 4, 5 were significantly lower than that of group 1 (p<0.05). 2. In the AM group, microleakage values of group 3 and 4 were significantly lower than that of group 1 (p<0.05), but microleakage values of group 2 and 5 did not differ from that of group 1 (p>0.05). 3. The GF group was similar(group, 1 3, 4) or superior(group 2, 5) to the AM group in the aspect of the microleakage.

• Advances in pediatric surgery
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• v.14 no.2
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• pp.164-172
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• 2008

The survival rate for rhabdomyosarcoma (RMS) has significantly improved after the introduction of combined multimodality treatment. We report the 20-year treatment outcome of pediatric rhabdomyosarcoma in a single institution. The medical records of 16 patients treated for rhabdomyosarcoma between December 1986 and August 2007 at the Department of Pediatric Surgery, Seoul National University Children's Hospital, were retrospectively reviewed. Mean age at diagnosis was 7.1 years (range: 1.3 -14.2 years). Retroperitoneum was the most common primary site (n=7, 43.8 %), and embryonal type was predominant (n=11, 6 %). Before the treatment, most patients were in advanced TNM stage (stage III 50 %, IV; 25 %). The patient distribution according to the Intergroup Rhabdomyosarcoma Study Clinical Grouping System (IRS-CGS) was as follows; Group I 31.3 %, Group II 12.5 %, Group III 31.3 % and Group IV 25 %. Patients were classified into three groups according to the extent of resection of the primary tumor; complete resection (CR, n=5; 31.3 %), gross total resection (GTR, n=7; 43.8 %) and incomplete resection (IR, n=4; 25 %). Recurrence was observed in 9 patients (56.3 %) while there was no recurrence in CR patients. All patients with recurrence were identified as moderate or high-risk according to the IRS-V Risk Group. Pre-treatment TNM stage of RMS in our institution was advanced with aggressive clinical feature, however postsurgical conditions according to IRS-CGS were similar to the previous reports by IRS. This suggests that down-staging of IRS-CGS was achieved with multimodality treatment with CR or GTR. It also suggests that complete resection is the most important prognostic factor in the treatment of RMS in children. Patients classified as moderate or high-risk need close follow-up due to high recurrence rate. In case of localized recurrence, better outcome may be achieved with multimodality treatment including limited surgery.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.1
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• pp.101-110
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• 2006

This study was performed to investigate the surface properties and in vitro biocompatibility of electrochemically oxidized Ti-6Al-7Nb alloy by anodic spark discharge technique. Discs of Ti-6Al-7Nb alloy of 20 mm in diameter and 2 mm in thickness were polished sequentially from #300 to 1000 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 using a regulated DC power supply. The applied voltages were given at 240, 280, 320, and 360 V and current density of $30mA/cm^2$. Hydrothermal treatment was conducted by high pressure steam at $300^{\circ}C$ for 2 hours using a autoclave. Samples were soaked in the Hanks' solution with pH 7.4 at $36.5^{\circ}C$ during 30 days. The results obtained were summarized as follows; 1. The oxide films were porous with pore size of $1{\sim}5{\mu}m$. The size of micropores increased with increasing the spark forming voltage. 2. The main crystal structure of the anodic oxide film was anatase type as analyzed with thin-film X-ray diffractometery. 3. Needle-like hydroxyapatie (HA) crystals were observed on anodic oxide films after hydrothermal treatment at $300^{\circ}C$ for 2 hours. The precipitation of HA crystals was accelerated with increasing the spark forming voltage. 4. The precipitation of the fine asperity-like HA crystals were observed after being immersed in Hanks' solution at $37^{\circ}C$. The precipitation of HA crystals was accelerated with increasing the spark forming voltage and the time of immersion in Hanks' solution. 5. The Ca/P ration of the precipitated HA layer was equivalent to that of HA crystal as increasing the spark forming voltage and the time of immersion in Hanks' solution.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.2
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• pp.113.2-113.2
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• 2011

We observed a low-mass pre-main sequence star, HBC722 (also known as $LkH{\alpha}$ 188 G4), with Camera for QUasars in EArly uNiverse (CQUEAN) attached to 2.1 Otto Struve telescope at McDonald Observatory, USA. HBC722 is a new FU orionis-type object in the direction of NGC7000/IC5070, which produced large amplitude optical outbursts (${\delta}V$=4.7 mag over one year) for a few months and reached the peak in 2010 September. We carried out the photometric observation in SDSS r,i, and z band in 2011 April, July and August to monitor the long term decrease of its brightness. We also made continuous observation in r-band for half night in July, and whole two nights in August to investigate short term variability which could be related to the rotation of the central star or the inner circumstellar disk. In this poster, we present a preliminary result of the photometric observation for HBC722.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.416-419
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• 2002

There are being two prominent studying for Digital Radiography. Direct and Indirect method of Digital Radiography are announced for producing high quality digital image. The one is using amorphous selenium as photoconductor and the other is using phosphor layer as a light conversion. But each two systems have strength and weakness such as high voltage and blurring effect. In this study, we investigated the electrical characteristic of $multi-layer\left(CaWO_{4}+a-Se \right)$ as a photoconductor according to the changing arsenic composition ratio. This is a basic research for developing of Hybrid digital radiography which is a new type X-ray detector. The arsenic composition ratio of a-Se compound is classified into 7 different kinds which have 0.1%, 0.3%, 0.5%, 1%, 1.5%, 5%, 10% and were made test sample throught thermo-evaporation. The phosphor layer of $CaWO_4$ was overlapped on a-Se using EFIRON optical adhesives. We measured the dark and photo current about the test sample and compared the electrical characteristic of the net charge and signal-to-noise ratio. Among other things, test sample of compound material of 0.3% arsenic showed good characteristic of $2.45nA/cm^2$ dark current and $357.19pC/cm^2/mR$ net charge at $3V/{\mu}m$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.08a
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• pp.85-88
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• 2003

$Sr_xBa_{1-x}Nb_2O_6$(SBN, $025{\leq}x{\leq}0.75$) ceramic is a ferroelectric material with tetragonal tungsten bronze (TTB) type structure, which has a high pyroelectric coefficient and a nonlinear electro-optic coefficient value. In spite of its advantages, SBN has not been investigated well compared to other ferroelectric materials with perovskite structure. In this study, SBN thin film was manufactured by ion beam sputtering technique using the prepared SBN target in Ar/$O_2$ atmosphere. SBN30 thin film of 500 ${\AA}$ was pre-deposited as a seed layer on Pt(l00)/$TiO_2$/$SiO_2$/Si substrate followed by SBN60 deposition up to 4500 ${\AA}$ in thickness. SBN60/SBN30 layer was deposited at different Oxygen amount of 0, 8.1, 17, and 31.8 sccm, respectively. The crystallinity and orientation behavior as well as electric properties of SBN60/SBN30 multi-layer were examined. The deposited layer was uniform and the orientation was shown primarily along (001) plane from XRD pattern. The crystal structure and the electric properties depended on the Oxygen amount, heating temperature and was the best at O2 = 8.1 seem, $750^{\circ}C$. In electric properties of Pt/SBN60/SBN30/Pt thin film capacitor prepared, the remnant polarization (2Pr) value was 13 ${\mu}C/cm^2$, the coercive field (Ec) 75 kV/cm, and the dielectric constant 1492, respectively.

• Advances in Traditional Medicine
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• v.5 no.3
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• pp.201-208
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• 2005

Earlier we have reported the antidiabetic activity of fresh juice of rhizomes of Zingiber officinale (Z. officinale) and its correlation with 5-HT receptor antagonism. Since 6-gingerol the marker compound of Z. officinale is reported to posses 5-HT anatgonistic activity, the present investigation, was undertaken to find out the concentration of 6-gingerol present in methanolic extract of Z. officinale and its different fractions (petroleum ether, toluene and chloroform). We also evaluated these fractions for antidiabetic activity in streptozotocin (STZ)-induced neonatal type 2 diabetic rats. Fasting glucose and insulin levels in non insulin dependent diabetes mellitus (NIDDM) rats were found to be significantly (P < 0.05) higher than control rats and these were significantly decreased by treatment with methanolic extract of Z. officinale and its fractions. The results of oral glucose tolerance test (OGTT) showed that methanolic extract and its fractions significantly (P < 0.05) decreased both STZ-induced increase in $AUC_{glucose}$ and $AUC_{insulin}$ values in NIDDM groups. Treatment with petroleum ether fraction produced a greater reduction in elevated glucose and $AUC_{glucose}$ levels as compared to treatment with other fractions. Treatment with methanolic extract of Z. officinale and its fractions also produced significant reduction in the elevated lipid, serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) levels in NIDDM rats. The effect of petroleum ether fraction on elevated lipid, SGOT and SGPT levels was significantly greater as compared to treatment with other fractions. The concentration of 6-gingerol was found to be maximum in petroleum ether fraction (11.430%) and minimum in chloroform fraction (0.973%). The methanolic extract and toluene fraction was found to contain 3.080% and 2.191 %, 6-gingerol respectively. In conclusion, our data suggest that methonolic extract and its fractions possess significant antidiabetic activity in NIDDM rats. The extent of activity appears to be dependent on the concentration of 6-gingerol present in the extract or its fractions.

• Structural Engineering and Mechanics
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• v.9 no.6
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• pp.615-636
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• 2000

Some elevated water tanks have failed due to torsional vibrations in past earthquakes. The overall axisymmetric structural geometry and mass distribution of such structures may leave only a small accidental eccentricity between centre of stiffness and centre of mass. Such a small accidental eccentricity is not expected to cause a torsional failure. This paper studies the possibility of amplified torsional behaviour of elevated water tanks due to such small accidental eccentricity in the elastic as well as inelastic range; using two simple idealized systems with two coupled lateral-torsional degrees of freedom. The systems are capable of retaining the characteristics of two extreme categories of water tanks namely, a) tanks on staging with less number of columns and panels and b) tanks on staging with large number of columns and panels. The study shows that the presence of a small eccentricity may lead to large displacement of the staging edge in the elastic range, if the torsional-to-lateral time period ratio $({\tau})$ of the elevated tanks lies within a critical range of 0.7< ${\tau}$ <1.25. Inelastic behaviour study reveals that such excessive displacement in some of the reinforced concrete staging elements may cause unsymmetric yielding. This may lead to progressive strength deterioration through successive yielding in same elements under cyclic loading during earthquakes. Such localized strength drop progressively develop large strength eccentricity resulting in large localized inelastic displacement and ductility demand, leading to failure. So, elevated water tanks should have ${\tau}$ outside the said critical range to avoid amplified torsional response. The tanks supported on staging with less number of columns and panels are found to have greater torsional vulnerability. Tanks located near faults seem to have torsional vulnerability for large ${\tau}$.

• Mycobiology
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• v.39 no.3
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• pp.187-193
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• 2011

Botryosphaeran, a water-soluble exopolysaccharide of the ${\beta}-(1{\rightarrow}3;1{\rightarrow}6)$-D-glucan type that has been isolated from the culture medium of Botryosphaeria rhodina MAMB-05 grown in submerged fermentation using glucose as the sole carbon source, was previously demonstrated to be non-genotoxic in peripheral blood and bone marrow, and exhibited strong anticlastogenic activity. In the present study, the effects of botryosphaeran were investigated in streptozotocin-induced diabetic rats as well as in high-fat diet-fed hyperlipidemic Wistar rats. The plasma glucose level was reduced by 52% in the diabetic group of rats after administration of 12 mg botryosphaeran/kg body weight of the rats (b.w.)/day by gavage over 15 days. A reduction in the median ration intake was accompanied by an increase in the median body weight gain, as well as the efficiency of food conversion. These results demonstrate that botryosphaeran has protective effects by reducing the symptoms of cachexia in Diabetes mellitus. Botryosphaeran administered by gavage at a concentration of 12 mg botryosphaeran/kg b.w./day over 15 days also reduced the plasma levels of total cholesterol and low density lipoprotein-cholesterol by 18% and 27%, respectively, in hyperlipidemic rats. Based on these findings, we conclude that botryosphaeran possesses hypoglycemic and hypocholesterolemic properties in conditions of diabetes mellitus and hyperlipidemia, respectively, and may be used as an oral anti-diabetic agent.