• Korean Journal of Materials Research
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• v.27 no.7
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• pp.381-385
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• 2017

In order to replace 14K white gold alloys, the properties of 5K white gold alloys (Au20-Ag80) were investigated by changing the contents of In (0.0-10.0 wt%). Energy dispersive X-ray spectroscopy (EDS) was used to determine the precise content of alloys. Properties of the alloys such as hardness, melting point, color difference, and corrosion resistance were determined using Vickers Hardness test, TGA-DTA, UV-VIS-NIR-colorimetry, and salt-spray tests, respectively. Wetting angle analysis was performed to determine the wettability of the alloys on plaster. The results of the EDS analysis confirmed that the Au-Ag-In alloys had been fabricated with the intended composition. The results of the Vickers hardness test revealed that each Au-Ag-In alloy had higher mechanical hardness than that of 14K white gold. TGA-DTA analysis showed that the melting point decreased with an increase in the In content. In particular, the alloy containing 10.0 wt% In showed a lower melting temperature (> $70^{\circ}C$) than the other alloys, which implied that alloys containing 10.0 wt% In can be used as soldering materials for Au-Ag-In alloys. Color difference analysis also revealed that all the Au-Ag-In alloys showed a color difference of less than 6.51 with respect to 14K white gold, which implied a white metallic color. A 72-h salt-spray test confirmed that the Au-AgIn alloys showed better corrosion resistance than 14K white gold alloys. All Au-Ag-In alloys showed wetting angle similar to that of 14K white gold alloys. It was observed that the 10.0 wt% In alloy had a very small wetting angle, further confirming it as a good soldering material for white metals. Our results show that white 5K Au-Ag-In alloys with appropriate properties might be successful substitutes for 14K white gold alloys.

• Korean Journal of Human Ecology
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• v.5 no.1
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• pp.62-70
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• 2002

The objective of this study was to evaluate the effects of processing parameters of co-rotating twin screw extruder and dry methods on the level of resistant starch (RS) and the properties of extrudate prepared from normal maize starch. The processing parameters were used 90, 110, 130$^{\circ}C$ in temperature, 25.0~30.0% in moisture content, 150, 200, 250 rpm in screw speed and hot and cool air drying and drying after refrigerating in drying methods. The barrel temperature and drying methods had affected the level of resistant starch of extrudate. RS levels of extrudates were ranged from 2.4 to 15.5% by AOAC method. The extrudates, extruded at 110$^{\circ}C$ and then stored at 4$^{\circ}C$, showed the highest level of RS level (15.5%). Water absorption index increased with increasing moisture content and peak temperatures and viscosities of extudates decreased compare to that of raw starch from 94$^{\circ}C$ to 50~65$^{\circ}C$ and from 220 to 46~98 RVU, respectively. Extudates treated in 90$^{\circ}C$ and 110$^{\circ}C$ showed strong peak at $2{\theta}=6.7{\sim}17.0^{\circ}$ by X-ray diffractometry and had ~150$^{\circ}C$ endotherm like as that of RS3 starch by differential scanning calorimetry. In case of 130$^{\circ}C$, extrudates showed strong peak at $2{\theta}=20.0^{\circ}$ and had 106$^{\circ}C$ endotherm.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.749-754
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• 2008

To increase the solubility of sibutramine freebase, the solid dispersion was prepared using a fluid-bed granulator. The solid dispersion containing sibutramine freebase was characterized by differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). After filling the sibutramine solid dispersion in the gelatin hard capsule, we performed in vitro dissolution test, the stability test under accelerated conditions and pharmacokinetic study in beagle dogs. The DSC and XRD data showed that sibutramine solid dispersion would be amorphous state. The dissolution rate of sibutramine solid dispersion was significantly increased about 70% than sibutramine freebase. The stability of sibutramine solid dispersion capsules was equivalent or above to commercial product of sibutramine. In beagle dogs, the sibutramine solid dispersion showed equivalent pharmacokinetic behavior with commercial product of sibutramine hydrochloride. In conclusion, the solid dispersion system provided a possible way to overcome the low solubility of sibutramine freebase, and the sibutramine solid dispersion can be a bioequivalent with the commercial product in humans.

• Korean Journal of Materials Research
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• v.13 no.4
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• pp.233-238
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• 2003

Ferromagnetic tunnel junctions, Ta/Cu/Ta/NiFe/Cu/$Mn_{75}$ $Ir_{25}$ $Co_{70}$ $Fe_{30}$/Al-oxide, were fabricated by do magnetron sputtering and plasma oxidation process. The effect of annealing temperature on the local transport properties of the ferromagnetic tunnel junctions was studied using contact-mode Atomic Force Microscopy (AFM). The current images reflected the distribution of the barrier height determined by local I-V analysis. The contrast of the current image became more homogeneous and smooth after annealing at $280^{\circ}C$. And the average barrier height $\phi_{ave}$ increased and its standard deviation $\sigma_{\phi}$ X decreased. For the cases of the annealing temperature more than $300^{\circ}C$, the contrast of the current image became large again. And the average barrier height $\phi_{ave}$ decreased and its standard deviation $\sigma_{\phi}$ increased. Also, the current histogram had a long tail in the high current region and became asymmetric. This result means the generation of the leakage current that is resulted from the local generation of a low barrier height region. In order to obtain the high tunnel magnetoresistance(TMR) ratio, the increase of the average barrier height and the decrease of the barrier height fluctuation must be strictly controlled.led.

• Journal of the Korean Magnetics Society
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• v.16 no.1
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• pp.66-70
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• 2006

Magnetite nanoparticles, which have been extensively used in many fields, were encapsulated with a natural polymer, chitosan, to improve their biocompatibility. We have synthesized magnetite $(Fe_3C_4)$ nanoparticles using chemical coprecipitation technique with sodium oleate as surfactant. Nanoparticle size can be varied from 1.2 to 7.4nm by controlling the sodium oleate concentration. Magnetite phase nanoparticles could be observed from X-ray diffraction. Magnetic colloid suspensions containing particles with sodium oleate and chitosan have been prepared. High magnetic property chitosan-microsphere particles were prepared from oleate-coated magnetite suspension using spray method. The surftce, and tile morphology of the magnetic chitosan microsphere particles were characterized using optical microscope and scanning electron microscope. Magnetic hysteresis measurement were performed using a superconducting quantum interference device (SQUID) magnetometer at room temperature to investigate the magnetic properties of the chitosan microspheres including magnetite nanoparticles. The SQUID measurements revealed superparamagnetism of nanoparticles.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3645-3650
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• 2012

Two new blue emitting cationic iridium(III) complexes with two substituted 2-phenlypyridine ligands as main ligands and one 2,2'-biimidazole as an ancillary ligand, $[(L1)_2Ir(biim)]Cl$ (1) and $[(L2)_2Ir(biim)]Cl$ (2), where L1 = 2-(2',4'-difluorophenyl)-4-methylpyridine, L2 = 2-(2',4'-difluoro-3'-trifluoromethylphenyl)-4-methylpyridine and biim = 2,2'-biimidazole, were synthesized for applications in phosphorescent organic light-emitting diodes (PhOLEDs). Their photophysical, electrochemical and electroluminescent (EL) device performances were examined. The photoluminescent (PL) spectra revealed blue phosphorescence in the 450 to 485 nm range with a quantum yield of more than 10%. The iridium(III) compounds studied showed good solubility in organic solvents with no solvatochromism dependent on the solvent polarity. The solution-processed OLEDs were prepared with the configuration, ITO/PEDOT:PSS (40 nm)/mCP:Ir(III) (70 nm)/OXD-7 (20 nm)/LiF (1 nm)/Al (100 nm), by spin coating the emitting layer containing the mCP host doped with the iridium phosphors. The best performance of the fabricated OLEDs based on compound 1 showed an external quantum efficiency of 4.5%, luminance efficiency of 8.52 cd $A^{-1}$ and blue emission with the CIE coordinates (x,y) of (0.16, 0.33).

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.12 no.1
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• pp.57-70
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• 2017

Objectives : The purpose of this study is to find out the factors affecting the cervical angle with kyphosis. Methods : We investigated 340 cases of patients who had cervical kyphosis. We used cervical angle, flexion malposition angle, odontoid process cline angle, axis-atlas cline angle, odontoid process-atlas cline angle and occiput-atlas cline angle. Correlations between cervical angle and flexion malposition angle, odontoid process cline angle, axis-atlas cline angle, odontoid process-atlas cline angle, occiput-atlas cline angle were analyzed by pearson correlation analysis. Results : The correlation between cervical angle and flexion malposition angle was p-value 0.007, and odontoid process cline angle was p-value 0.002, and axis-atlas cline angle was p-value 0.000, and odontoid process-atlas cline angle was p-value 0.000, and occiput-atlas cline angle was p-value 0.012. Conclusions : Flexion malposition angle, odontoid process cline angle are inversely proportional to cervical angle. And correlation is statistically significant(p<0.01). Axis-atlas cline angle, odontoid process-atlas cline angle are proportional to cervical angle. And correlation is statistically significant(p<0.01). Occiput-atlas cline angle is proportional to cervical angle. And correlation is statistically significant(p<0.05).

• Journal of Korean Academy of Nursing
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• v.22 no.1
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• pp.29-41
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• 1992

The purpose of this research was to study the effects of antenatal breast care on decreases in breast discomfort and increases in the breast feeding rate during the postpartum period. A nonequivalent control group posttest research design was used. The experimental group consisted of fifty -one pregnant women(primigravida) who were receiving antenatal care in the OBGYN clinics of four hospitals between March 5 and May 30, 1991. The control group was made up of seventy - five postpartum women who delivered at two hospitals OBGYN clinic and one midwife clinic between May 4 and June 15, and between September 5 and October 15, 1991. Data were collected via telephone interviews on the seventh postpartum day and at the end of the second month. Data analysis methods used frequencies and the x$^2$- test. The results were as follows : 1. The rate of breast feeding practice at two months was higher in the experimental group(70.6%) than in the control group(25.3%) (p＜.01). 2. Nipple soreness in the early breast feeding period was lower in the experimental group(14.6%) than in the control group(25.3)(p＜.01). 3. Severe breast discomfort in the early breast feeding period was lower in the experimental group (12.5%) than in the control group(39.2%)(P＜.01). 4. There was a significant relationship between the breast feeding practice and the planned feeding method(p＜.05), and between breast feeding practice and nipple soreness(p＜.01) in the experimental group, and the presence of a job(p＜.01), the sex of the infant(p＜.05), and the first feeding time(p＜.05) in the control group. 5. The reasons for unsuccessful breast feeding were a deficiency of breast milk (66.7% in the experimental group, 30.4% in the control group), poor sucking on the part of the baby(13.3% in the experimental group, 21.4% in the control group).

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.2
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• pp.315-322
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• 1993

To evaluate of the relationship between the TMJ disorder and the vertical mandibular asymmetry, the author analyzed the differences between condylar heights, ramus heights and mandibular heights of both sides. All measurements were performed with a digital micrometer on the panoramic radiographs of 36 TMJ disorder patients and 30 normal control group. The differences were expressed in millimeters and percentage using the following formula; ｜(R-L)/(R+L)｜×100% The results were as follows : 1. The condylar height difference was greater of in patient group (1.86±1.66㎜) than that of in control group (1.22±0.85㎜)(p<0.05). But there was no significant difference in the condylar height ratio difference between patient group (11.67㎜11.44%) and control group (7.64±621%) (p>0.05). 2. The ramus height difference and ramus height ratio difference of patient group (4.52±3.70㎜, 4.39±3.49%) were greater than those of control group (2.64±2.13㎜, 2.46±2.02%)(p<0.05, p<0.01). 3. The mandibular height difference and mandibular height ratio difference of patient group (4.32±3.52㎜, 3.59±2.81%) were greater than those of control group (2.57±2.46㎜, 2.01±1.95%) (p<0.05). 4. The ratio difference in condylar height to ramus height and condylar height to mandibular height of patient group (5.01±4.13%, 3.36±2.88%) were greater than those of control group (2.33±1.78%, 1.90±1.40%) (p<0.01).

• The Journal of Advanced Prosthodontics
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• v.12 no.2
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• pp.89-99
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• 2020

PURPOSE. The effects of four different self-adhesive resin cement materials on cell viability and apoptosis after direct and indirect exposure were evaluated using different cell culture techniques. MATERIALS AND METHODS. Self-adhesive cements were applied to NIH/3T3 mouse fibroblasts by the extract test method, cell culture inserts, and dentin barrier test method. After exposure periods of 24 h and 72 h, the cytotoxicity of these self-adhesive materials was evaluated using the MTT assay (viability) and the Annexin-V-FITC/PI staining (apoptosis). RESULTS. The lowest cell viability was found in cells exposed to BeautiCem SA for 24 h in the extract test method. Cell viability was reduced to 70.6% compared to negative controls. After the 72 h exposure period, viability rate of cell cultures exposed to BeautiCem SA decreased more than 2- fold (29.5%) while cells exposed to RelyX U200 showed the highest viability rate of 71.4%. In the dentin barrier test method, BeautiCem SA induced the highest number of cells in apoptosis after a 24 h exposure (4.1%). Panavia SA Cement Plus was the material that caused the lowest number of cells in apoptosis (1.5%). CONCLUSION. The used self-adhesive cements have showed different cytotoxic effects based on the evaluation method. As exposure time increased, the materials showed more cytotoxic and apoptotic effects. BeautiCem SA caused significantly more severe cytotoxic and apoptotic effects than other cements tested. Moreover, cements other than BeautiCem SA have caused necrotic cell death rather than apoptotic cell death.