• The Korean Journal of Ceramics
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• v.6 no.3
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• pp.291-295
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• 2000

The pyroelectric property of $Pb_{0.9}La$_{0.1}TiO_3$ceramics in a range of 1.3-4.1$\mu\textrm{m}$, fabricated by conventional solid sintering, was investigated as a function of poling field. The pyroelectric of the 4.1$\mu\textrm{m}$ of $Pb_{0.9}La$_{0.1}TiO_3$ceramics is higher than that of the 1.3$\mu\textrm{m}$ and 1.7$\mu\textrm{m}$ of $Pb_{0.9}La$_{0.1}TiO_3$ceramics at a low poling field and the pyroelectric coefficient is 25nC/$\textrm{cm}^2$K at a 4kV/mm poling field in every grain size. In order to explain this phenomenon, the intrinsic and extrinsic effects in view of the definition of the pyroelectric coefficient are introduced. The intrinsic and extrinsic effects on the pyroelectric property were investigated by measuring the tetragonal ratio and the $I_{002}$ with temperature with high temperature X-ray diffractometer. The change of spontaneous polarization and the $90^{\circ}$domain wall motion with temperature in the 1.3$\mu\textrm{m}$ and 4.2$\mu\textrm{m}$ of $Pb_{0.9}La$_{0.1}TiO_3$ceramics have no effects on the pyroelectric coefficient. In our study, it can be seen that the pyroelectric coefficient is related to the quantity of $180^{\circ}$domain switching after poling treatment.

• Korean Journal of Materials Research
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• v.27 no.4
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• pp.216-220
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• 2017

The effect of electron beam (EB) irradiation on the electrical properties of Zn-Sn-O (ZTO) thin films fabricated using a sol-gel process was investigated. As the EB dose increased, the saturation mobility of ZTO thin film transistors (TFTs) was found to slightly decrease, and the subthreshold swing and on/off ratio degenerated. X-ray photoelectron spectroscopy analysis of the O 1s core level showed that the relative area of oxygen vacancies ($V_O$) increased from 10.35 to 12.56 % as the EB dose increased from 0 to $7.5{\times}10^{16}electrons/cm^2$. Also, spectroscopic ellipsometry analysis showed that the optical band gap varied from 3.53 to 3.96 eV with increasing EB dose. From the results of the electrical property and XPS analyses of the ZTO TFTs, it was found that the electrical characteristic of the ZTO thin films changed from semiconductor to conductor with increasing EB dose. It is thought that the electrical property change is due to the formation of defect sites like oxygen vacancies.

• Journal of Pharmaceutical Investigation
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• v.41 no.3
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• pp.179-184
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• 2011

This study aimed to confirm the effect of molecular weight (MW) in solid dispersion of carvedilol with poly-vinylpyrrolidone (PVP) of various MW. Solid dispersion of carvedilol with PVP was prepared by spray-drying method. Scanning electron microscopy (SEM) was used to analyze the surface of solid dispersion samples. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were used to analyze the crystalline of solid dispersion. Fourier transform infrared spectroscopy (FT-IR) was used to analyze the change of chemical structure characteristic of solid dispersion. DSC and XRD show that drug crystalline was changed. FT-IR revealed that chemical structure of solid dispersion comparing the chemical structure of drug was changed. The dissolution studies of solid dispersion presented at simulated gastric juice (pH 1.2). The dissolution rate of solid dispersion was dramatically enhanced than pure drug and the MW of PVP has an effect on the release property of carvedilol in solid dispersion. In conclusion, the present study has confirmed the effect of MW of PVP on release property of solid dispersion formulation of carvedilol with PVP.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.6
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• pp.1548-1554
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• 2008

The market of silver precious metal clay (PMC) is promising as its application for agile metal craft. The property of suitable hardness and shrinkage as well as environment-safe is strictly required as people make the final product with bare hands. We propose a silver PMC with new organic binder made of palm oil, glycolic acid and water. Then we prepared disk specimen of our proposed PMC and well-known commercial PMC. We investigated the hardness, weight change, linear shrinkage, density and micro structure evolution with sintering temperature of $700{\sim}900^{\circ}C$ ($50^{\circ}C$ gap) for 15minutes. We confirm our proposed PMC has suitable property for craft product comparable for commercial PMC, and the optimum sintering condition is $850^{\circ}C$-15minutes for metal craft application.

• Journal of Korea Foundry Society
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• v.35 no.3
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• pp.45-52
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• 2015

The effect of different C and Cr/Mo contents, which were varied within the range allowed in the relevant specification, on the mechanical and corrosion properties of A487 alloy cast steel were examined. The increase in strength level with increasing C content and the decrease in strength along with the increase in tensile elongation with decreasing Cr/Mo contents were observed in A487 alloys with different C and Cr/Mo contents. At room temperature, the decrease in Cr/Mo content was beneficial in improving the impact properties of A487 alloy, with no notable difference in absorbed energy with varying C content. The impact properties of A487 alloy at $-60^{\circ}C$, on the other hand, greatly improved with the increase in C and the decrease in Cr/Mo contents. The corrosion behavior of A487 alloys in 3.5% NaCl solution did not show any meaningful change with different C and Cr/Mo contents.

• Journal of the Korean Geotechnical Society
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• v.37 no.4
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• pp.5-17
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• 2021

In this paper, three-dimensional analysis of the curved levee was performed according to curvature angle, and radius of curvature to investigate the property of seepage. The hydraulic gradients in the curved parts of levees decreased in the outer levee and increased in the inner levee, compared to the two-dimensional analysis. The smaller the curvature angle and the radius of curvature, the larger the change of the hydraulic gradient, compared to the two-dimensional analysis. The effect of curvature radius on the hydraulic gradient was greater than the curvature angle. As a result of evaluating the piping safety factor for the critical hydraulic gradient, the safety factor was increased by 2~5% in the outer levee and decreased by 4~12% in the inner levee, compared to the two-dimensional analysis. Considering this reduction, if the two-dimensional analysis is performed on the curved part of the levee, and if designed the safety factor for piping is 0.1~0.3 greater than allowable FS=2.0, the safety factor of the curved part is slightly reduced, but there is no difficulty in securing stability.

• Food Engineering Progress
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• v.13 no.4
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• pp.335-340
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• 2009

This study was performed to analyze changes in the molecular structural and physical properties of modified corn starch, in which particle structure was broken using high impact planetary mill and ultra fine pulverizing techniques. The average diameter and specific surface area of the modditied corn starch after pulverization decreased 50% and increased 567%, respectively. Content of low molecular substances mersured using gel permeation chromatography (GPC) increased from 21.0% to 86.5% after pulverizing corn starch. Damaged starch content also increased from 9.63% to 83.57% after pulverizing corn starch. After pulverization, gel formation capacity corn starch was reduced compared to that of control by structure breakdown.

• Journal of the Korea Institute of Building Construction
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• v.19 no.1
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• pp.59-66
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• 2019

In this study, the effects of blast furnance slag cement and frost-resistant accelerator on shrinkage properties and shrinkage properties of mortar were examined. As a result, the addition of the frost-resistant accelerator to both OPC and BB has a small effect on the flash properties of mortar and the compressive strength increases from the early ages. In addition, when a frost-resistant accelerator is used in excess of the standard usage amount, it is necessary to examine the relationship of the expansion behavior at the early age, especially, between the compressive strength development and the expansion property. And it was confirmed that the addition of the frost-resistant accelerator tended to increase the shrinkage of mortar using the OPC and BB. With the addition of the frost-resistant accelerator, the amount of pores with a diameter of under the 30nm, especially, the amount of pores with a diameter of 20 to 30nm and the amount of pores with an ink-bottle decrease, and the shrinkage increases. And it is considered that a change in the amount this range of pores has a large effect on the shrinkage property.

• Journal of Korean Academy of Nursing Administration
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• v.1 no.2
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• pp.285-324
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• 1995

The purpose of this study was to describe the nature of nursing and life style of nurses. This study was conducted from march, 1994 to May, 1995. There are two kinds of data used in this research. To discern the nature of nursing and life style of nurses, 34 articles selected from nursing journals and text books, and the data which were collected by unstructured questionare with two main open ended questions were analyzed using Strauss and Corbin's method. The questions were "what is nature of nursing?" "When do you feel your professionl life worth?" 29 participants were nurses working at two university hospitals and two general hospitals in Seoul, understood the study purpose. The results were as follows : (1) The nursing is evolving phenomenon which is developed, and changed. (1) ${\lceil}$encounter${\rfloor}$ ${\lceil}$trust${\rfloor}$ ${\lceil}$interrelationship${\rfloor}$have been identified as the causal condition of nursing phenomenon. (2) ${\lceil}$concern${\rfloor}$has been identified as the central phenomenon of nursing. (3) ${\lceil}$humanity${\rfloor}$ ${\lceil}$sincerity${\rfloor}$ ${\lceil}$nursing spirit${\rfloor}$ ${\lceil}$empathy${\rfloor}$ ${\lceil}$understanding${\rfloor}$have been identified as intervening condition and context of nursing phenomenon. (4) ${\lceil}$helping behavior${\rfloor}$has been identified as action/strategy of nursing phenomenon. (5) ${\lceil}$caring${\rfloor}$ ${\lceil}$observation${\rfloor}$ ${\lceil}$comfort${\rfloor}$ ${\lceil}$problem solving${\rfloor}$ ${\lceil}$co-ordination${\rfloor}$ ${\lceil}$education${\rfloor}$ ${\lceil}$stimulus${\rfloor}$have been as helping behavior. (6) ${\lceil}$change${\rfloor}$ ${\lceil}$growth and development${\rfloor}$ ${\lceil}$to do by oneself${\rfloor}$ have been as consequences of nursing phenomenon. (2) the nature of nursing have been classified into five properties ; ${\lceil}$relational property${\rfloor}$ ${\lceil}$moral property${\rfloor}$ ${\lceil}$technological property${\rfloor}$ ${\lceil}$behavioral property${\rfloor}$ ${\lceil}$objective property${\rfloor}$ (3) The life style of nurses is not considered as ${\lceil}$to have${\rfloor}$ living mode, but ${\lceil}$to be${\rfloor}$ living mode because the professional life of nurses is chracterized by ${\lceil}$encounter${\rfloor}$ ${\lceil}$trust${\rfloor}$ ${\lceil}$humanity${\rfloor}$ ${\lceil}$understanding${\rfloor}$ ${\lceil}$concern${\rfloor}$ ${\lceil}$togetherness with human being${\rfloor}$ ${\lceil}$growth and development${\rfloor}$ and others, which are properties of the nature of nursing, and are also considered as esential factors of real existence of professional nurse as a human being in nursing situation.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.331-338
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• 2008

Coal-tar enamel, blown asphalt and polyethylene have been used as wrapping materials of steel pipe in Korea. Currently, every manufacturer produces wrapped steel pipes with different materials and methods, and little research has been performed to get on wrapping methods and materials. In this research, properties of wrapping material of steel pipe used for water supply have been evaluated. All of the materials tested in this work were found to meet the standard. Among the wrapping materials of steel pipe tested, blown asphalt and coal-tar enamel were reasonable in price, and their mechanical properties were excellent. The quality of the wrapped steel pipes was being melted easily in organic solvent. When coated thick, the load of the steel pipes was higher than necessary. Tensile strength of cathode exfoliation and PE 3-layer wrapping method was excellent. The pulling intensity of T-Die PE 3-layer was stronger than PE fluidized in PE wrapping method. Cathode exfoliation area was smaller than PE fluidized. Mechanical property and thermo-property of T-Die PE 3-layer were excellent and its anti-chemical property was great. Liquid epoxy can change the property of coating materials depending on the hardening condition and resin selection. Polyurethane used in this test showed a less adhesive strength with steel pipes than epoxy. Moisture absorbance rate was higher than Epoxy's, however. To utilize polyurethane as wrapping materials, basic property of the matter should be improved followed by finding the best suited coating condition. The method of PE 3-layer by extrude method appeared to be the best in this study. However, identification of other wrapping materials requires further additional tests.