• The Journal of Korean Academy of Prosthodontics
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• v.36 no.3
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• pp.453-467
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• 1998

This study helps to clarify conflicting reports by comparing the physical properties and accuracy of complete denture processed by the pack and press technique, continuous- pressure injection technique(SR-Ivocap system) and Mark press technique. The 6 different specimens have been evaluated using the SEM, Impact test, DSC (Differential Scanning Calorimetry) and DMTA (Dynamic Mechanical Thermal Analysis). Each sample was made of SR-Ivocap resin and QC-20 resin by different processing methods. The results were as follows ; 1. As the result of the observation on the fracture surface of resin by use of SEM, sample SR-Ivocap resin cured by continuous pressure injection method showed the most homogeneous structure. This is why molecules in SR-Ivocap resin have no orientation. 2. As the result of the Impact test in order to measure the deformity, fracture energy and impact resistance of resin, the samples with QC-20 acrylic resin and SR-Ivocap resin cured by continuous pressure injection method were exellent. 3. In consequence of measuring ${\alpha}$-glass transition temperature by use of DSC on the basis of temperature change, the glass transition temperatures of sample QC-20 resin cured by pack and press method and sample SR-Ivocap resin cured by continuous pressure injection method were very similar. Thus volumetric stability could not be evaluated only by glass transition temperature. 4. In comparing volumetric stability data by DMTA, the glass transition temperature(Tg) showed $137.88^{\circ}C$ at sample QC-20 resin cured by pack and press method and $139.78^{\circ}C$ at sample SR-Ivocap resin cured by continuous pressure injection method. Therefore sample SR-Ivocap resin cured by continuous pressure injection method seems to be superior to sample QC-20 resin cured by pack and press method in the dimensional stability at high temperature. 5. In comparing storage modulus data by DMTA, the storage modulus of sample SR-Ivocap resin cured by continuous pressure injection method was higher than that of sample QC-20 resin cured by pack and press method. So. sample SR-Ivocap resin cured by continuous pressure injection method seems to be superior to sample QC-20 resin cured by pack and press method in impact strength.

• Polymer(Korea)
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• v.29 no.2
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• pp.183-189
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• 2005

Films of poly(vinyl alcohol)(PVA)/chitosan blends and its blend hydrogels were prepared by the solution casting method. The state of miscibility of the blends and blend hydrogels were examined over the entire composition range by differential scanning carorimetry (DSC), thermogravimetry (TGA), and dynamic mechanical analysis (DMA). DSC analysis shows the depression of melting point of PVA in the blends and the decrease of crystallization temperature of PVA in the blends were observed with increasing chitosan content in the blends. TGA analysis indicates that chitosan was thermally more stable than PVA and the thermal stability of PVA in the blends was higher than that of pure PVA, due to some interactions between two component polymers in the blend. The glass transition temperature $(T_g)$ of the chitosan and of PVA, measured by DMA, were at 160 and $90^{\circ}C$, respectively. The $T_g$ of the blends was changed with the content of chitosan in the blends. The results of thermal and viscoelastic analysis indicate some miscibility between component polymers in the blend exists. Moisture and cross linking in the blend and blend hydrogel, which strongly change thermal and physical properties of hydrophilic polymers, affected the miscibility of chitosan and PVA to a small extent.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.512-519
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• 2007

The purpose of this study is to investigate the potential of a novel tissue engineering approach to regenerate intervertebral disc. In this study, thermosensitive scaffold (chitosan-Pluronic hydrogel) and nanofiber were used to replace the nucleus pulposus (NP) and annulus fibrosus of a degenerated intervertebral disc, leading to an eventual regeneration of the disc using the minimally invasive surgical procedure and organ culture. In preliminary study, disc cells were seeded into the scaffolds and cellular responses were assessed by MTT assay and scanning electron microscopy (SEM). Based on these results, we could know that tissue engineered scaffolds might provide favorable environments for the regeneration of tissues. Organ culture was performed in fresh porcine spinal motion segments with endplates on both sides. These spinal motion segments were classified into three groups: control (Intact), injured NP (Defect), and inserting tissue engineered scaffolds (Insert). The specimens were cultivated for 7 days, subsequently structural stability, cell proliferation and morphological changes were evaluated by the relaxation time, quantity of DNA, GAG and histological examination. In these results, inserting group showed higher relaxation time, reduced decrement of DNA contents, and accumulated GAG amount. Consequently, the tissue engineered scaffolds used in this study seen to be a promising base scaffolds for regenerative intervertebral disc due to its capacity to absorb external dynamic loading and the possible ideal environment provided for disc cell growing.

• The Journal of the Korea Contents Association
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• v.15 no.9
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• pp.418-424
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• 2015

In this study, we proceed if there are any changes in binding ability of receptor-ligand in some degree of SA and in radioactive uptake from the corpus striatum based on small animal experiment in vivo based on the S.A values. By dividing 18F-Fallypride into 3 S.A values(high S.A : 43.29~74 GBq/umol, ordinary S.A : 20.72~29.23 GBq/umol, low S.A : 6.29~8.51 GBq/umol), we injected directly into the veins and performed 90 minutes of dynamic scan using Micro PET. After scanning, we compared and analyzed with Binding Potential (Binding Potential) from the bilateral striatum. high SA and low SA, ordinary SA and low SA showed significant differences. Also, in the image comparison using 18F-Fallypride show high radioactive uptake in the striatum at high SA and ordinary SA, but the radioactive uptake at low SA is lower than other two SA. Since 18F-Fallypride has affinity to dopamine D2/3 pharmacokinetic, the difference of Binding Potentials at decreased level of SA values was not that significant. However, further PET research of the corpus striatum using 18F-Fallypride is necessary because the differences in images and Binding Potentials at 6.5 times smaller SA values compared to high SA value showed were significant.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.11
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• pp.18-24
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• 2000

(Ba,Sr)$TiO_3$ thin films have attracted great interest as new dielectric materials of capacitors for ultra-large-scale integrated dynamic random access memories (ULSI-DRAMs) such as 1 Gbit or 4 Gbit. In this study, inductively coupled $BCl_3/Cl_2/Ar$ plasmas was used to etch (Ba,Sr)$TiO_3$ thin films. RF power/dc bias voltage=600 W/-250 V and chamber pressure was 10 mTorr. The $Cl_2/(Cl_2+Ar)$ was fixed at 0.2 the (Ba,Sr)$TiO_3$ thin films were etched adding $BCl_3$. The highest (Ba,Sr)$TiO_3$ etch rate is $480{\AA}/min$ at 10 % $BCl_3$ to $Cl_2/Ar$. The change of Cl, B radical density measured by optical emission spectroscopy(OES) as a function of $BCl_3$ percentage in $Cl_2/Ar$. The highest Cl radical density was shown at the addition of 10% $BCl_3$ to $Cl_2/Ar$. To study on the surface reaction of (Ba, Sr)$TiO_3$ thin films was investigated by XPS analysis. Ion bombardment etching is necessary to break Ba-O bond and to remove $BaCl_2$. There is a little chemical reaction between Sr and Cl, but Sr is removed by physical sputtering. There is a chemical reaction between Ti and Cl, and $TiCl_4$ is removed with ease. The cross-sectional of (Ba,Sr)$TiO_3$ thin film was investigated by scanning electron microscopy (SEM), the etch slope is about 65~70$^{\circ}$.

• Applied Chemistry for Engineering
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• v.24 no.3
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• pp.305-313
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• 2013

In this study, we investigated effects of thermal annealing on the thermal properties and microphase separation behaviors of glycidyl azide-based thermoplastic polyurethane elastomers (ETPE). The GAP-based ETPEs were characterized by attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), differential scanning calorimeter (DSC), dynamic mechanical analysis (DMA), and gel permeation chromatography (GPC). The effects of annealing temperature conditions ($80{\sim}130^{\circ}C$, 1 h or 24 h) on the properties of the ETPEs were investigated. The intensity of azide group absorption peak of ATR-FTIR spectra and the solubility of ETPE for methylene chloride and dimethylformamide solvent decreased after the annealing at $130^{\circ}C$ for 1 h and at $105^{\circ}C$ for 24 h. With increasing the annealing temperature from $80^{\circ}C$ to $110^{\circ}C$, the high temperature rubbery plateau region of storage modulus curves from DMA thermogram for GAP-based ETPEs was extended to the higher temperature.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.433-433
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• 2012

As the requirement in patterning geometry continuously shrinks down, the termination of etch process at the exact time became crucial for the success in nano patterning technology. By virtue of real-time optical emission spectroscopy (OES), etch end point detection (EPD) technique continuously develops; however, it also faced with difficulty in low open ratio etching, typically in self aligned contact (SAC) and one cylinder contact (OCS), because of very small amount of optical emission from by-product gas species in the bulk plasma glow discharge. In developing etching process, one may observe that coupon test is being performed. It consumes costs and time for preparing the patterned sample wafers every test in priority, so the coupon wafer test instead of the whole patterned wafer is beneficial for testing and developing etch process condition. We also can observe that etch open area is varied with the number of coupons on a dummy wafer. However, this can be a misleading in OES study. If the coupon wafer test are monitored using OES, we can conjecture the endpoint by experienced method, but considering by data, the materials for residual area by being etched open area are needed to consider. In this research, we compare and analysis the OES data for coupon wafer test results for monitoring about the conditions that the areas except the patterns on the coupon wafers for real-time process monitoring. In this research, we compared two cases, first one is etching the coupon wafers attached on the carrier wafer that is covered by the photoresist, and other case is etching the coupon wafers on the chuck. For comparing the emission intensity, we chose the four chemical species (SiF2, N2, CO, CN), and for comparing the etched profile, measured by scanning electron microscope (SEM). In addition, we adopted the Dynamic Time Warping (DTW) algorithm for analyzing the chose OES data patterns, and analysis the covariance and coefficient for statistical method. After the result, coupon wafers are over-etched for without carrier wafer groups, while with carrier wafer groups are under-etched. And the CN emission intensity has significant difference compare with OES raw data. Based on these results, it necessary to reasonable analysis of the OES data to adopt the pre-data processing and algorithms, and the result will influence the reliability for relation of coupon wafer test and whole wafer test.

• Polymer(Korea)
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• v.30 no.5
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• pp.385-390
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• 2006

In this work, the effect of carbon nanofiber (CNF) on thermal properties, and friction and wear behavior of CNF/PMMA composites were examined. While thermal properties of the composites were investigated with differential scanning calorimetry, thermograyimetric analyzer, and dynamic mechanical analyzer friction and wear behaviors were examined using a friction and wear tester. The glass transition temperature (Tg), integral procedural decomposition temperature (IPDT), storage modulus (E'), and tan ${\delta}$ appeared at higher temperatures with increasing CNF content, which were probably attributed to the presence of strong interactions between the carbonaceous fillers and the PMMA resins matrix. The wear loss in the composites decreased at 0.1 wt% CNF and then increased with 5-10 wt% CNF content. This was due to the existence of large aspect ratio CNF in PMMA which led to an alignment of PMMA chains and an increase of mechanical interlocking, resulting in the formation of crosslinked structures between CNF and PMMA in the composite.

• The Korean Journal of Food And Nutrition
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• v.29 no.3
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• pp.371-381
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• 2016

The present study investigated the effects of processing parameters such as time (10, 20, 30, 40 min), pressure (25, 50, 75, 100 MPa), and the salinity of brine (0~10%(w/v)) on jacopever (Sebastes schlegeli Hilgendorf) in order to establish optimization of the three factors using a high hydrostatic pressure (HHP) machine. To do so, it analyzed the quality characteristics of volatile basic nitrogen (VBN), trimethylamine (TMA), total bacterial counts, dynamic viscoelasticities, and differential scanning calorimetry (DSC) properties. First, when the time increased to 40 mins, by 10 min intervals, the total bacterial counts in HHP groups under $25^{\circ}C$, 100 MPa, and 4%(w/v) brine were significantly decreased except for the first 10 min in comparison to the control group. In regards to DSC properties, the onset temperature ($T_O$) of the first endothermal curve was significantly reduced. Second, when the pressure level increased up to 100 MPa by 25 MPa increments, the total bacterial counts in the HHP samples significantly decreased for 20 min at 50 MPa or higher. As the pressure increased, G', G" and the slope of tan ${\delta}$ decreased (except for 50 MPa). Third, in regards to the salinities of brine, when the HHP processing was treated at 100 MPa, $25^{\circ}C$ for 20 min, the total bacterial counts of all the HHP groups significantly decreased in comparison to those of the control group. A significant difference was found in the enthalpy of the second endothermic curve in the 6~10%(w/v) (except 7%(w/v)) HHP groups. Therefore, the salinity of the immersion water under the HHP condition was appropriate when it was lower than 6%(w/v). The present study demonstrated that the optimum parameter condition according to/under the condition of the microbial inhibition and economic effects using an HHP would be the reaction time for 20 min, reaction pressure at 100 MPa, and the salinity of 4%(w/v) brine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.46 no.5
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• pp.608-615
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• 2017

The objective of this study was to evaluate the physicochemical, structural, and rheological properties of new domestic potato cultivars ('Goun', 'Sebong', and 'Jinsun') against the foreign potato cultivar 'Atlantic'. Based on the results obtained from scanning electron micrograph, X-ray, and Fourier transform infrared spectrum analyses, the structural properties of all potato flours were not considerably different. Rapid visco analyzer analyses showed that the setback viscosities of 'Goun', 'Sebong', and 'Jinsun' were significantly lower than that of 'Atlantic'. For steady shear rheological properties, potato flour dispersions showed shear-thinning behaviors (n=0.45~0.49) at $25^{\circ}C$. Apparent viscosity and consistency index of 'Atlantic' were similar to those of 'Sebong' and 'Jinsun'. For dynamic shear rheological properties, storage modulus (G′) and loss modulus increased, whereas complex viscosity (${\eta}^*$) was reduced with increasing frequency from 0.63 to 62.8 rad/s. G′ and ${\eta}^*$ values of 'Jinsun' were significantly higher than those of the other potato cultivars.