• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.7
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• pp.447-452
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• 1987

In this paper, the dependence of piezoelectric properties in the 0-3 composite system of piezoelectric-ceramics polymer materials on particle size of ceramics were investigated. Radial mode and thickness mode of composite were observed similar to single phase of piezoelectric ceramics. The measured values of dielectric constant and dissipation factor were dependent on particle size, which increased with the increasing particle size. the planar coupling factor, thickness coupling factor and thickness frequency constant with the particle size were almost constant, while planar frequency constant increased. The thickness coupling factor decreased with the increasing thickness of specimen. It is found that maximum voltage coeffidient was calculated on the specimen with particle size smallar than 46 ${\mu}m$.

• Advances in materials Research
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• v.2 no.2
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• pp.99-109
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• 2013

In the present investigation, nanocomposite films with poly(methyl methacrylate) (PMMA) as a polymer matrix and barium titanate as a filler were prepared by solution casting method. Barium titanate nano particles were prepared using Ti(IV) triethanolaminato isopropoxide and hydrated barium hydroxide as precursors and tetra methyl ammonium hydroxide (TMAH) as a base. The nanocomposite films were characterized using XRD, FTIR, SEM and dielectric spectroscopy techniques. Dielectric measurements were performed in the frequency range 100 Hz-10 MHz. Dielectric constant of nanocomposites were found to depend on the frequency, the temperature and the filler fraction. Dissipation factors were also influenced by the frequency and the temperature but not much influenced by the filler fractions. The 10 wt% of BT-PMMA nanocomposite had the lowest dielectric constant of 3.58 and dielectric loss tangent of 0.024 at 1MHz and $25^{\circ}C$. The dielectric mixing model of Modified Lichtenecker showed the close fit to the experimental data.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.19-25
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• 2000

Dielectric polymer films produced from benzocyclobutene (BCB) formulations (CYCLOTENE＊ family resins) are known to possess many desirable properties for microelectronic applications; for example, low dielectric constant and dissipation factor, low moisture absorption, rapid curing on hot plate without reaction by-products, minimum shrinkage in curing process, and no Cu migration issues. Recently, BCB-based products for thick film applications have been developed, which exhibited excellent dissipation factor and dielectric constant well into the GHz range, 0.002 and 2.50, respectively. Derived from these properties, the applications are developed in: bumping/wafer level packaging, Ga/As chip ILD, optical waveguide, flat panel display, and lately in BCB-coated Cu foil for build-up board. In this paper, we review the relevant properties of BCB, then the application areas in bumping/wafer level packaging and BCB-coated Cu foil for build-up board.

• Transactions on Electrical and Electronic Materials
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• v.18 no.6
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• pp.338-340
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• 2017

Breakdown of solid insulating materials in power equipment could result in undesired outages and replacements, and may be due to an increase in electric stress on the material. Therefore, it is necessary to conduct a proper diagnosis of materials before their practical use. In this work, a few inherent properties of different non-cellulosic insulating materials, such as Nomex, Teflon, laminated Nomex, glass bonded mica, epoxy resin bonded mica paper, and epoxy resin bonded fiberglass, have been evaluated by performing non-destructive dielectric diagnostic measurements, and an attempt has been made to correlate these basic parameters to evaluate the breakdown strength (BDS). An equation has been proposed using a basic theory which defines the correlation between the BDS, dielectric constant, dissipation factor, sample thickness, and volume resistivity. The results obtained from the equation are also compared with the experimental values. The suggested equation will be helpful to predict the BDS of any non-cellulosic material without experimentation in the laboratory.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.125-129
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• 2004

[ $BaTi_4O_9$ ] thin film were grown on $Pt/Ti/SiO_2/Si$ substrate using rf magnetron sputter, and the microstructure and dielectric properties of the thin films were investigated. For the film grown at $350^{\circ}C$ and rapidly thermal annealed at $900^{\circ}C$, the $BaTi_5O_{11}$ Phase was formed. However, the $BaTi_4O_9$ phase was formed when the growing temperature exceeded $450^{\circ}C$ The dielectric constant of the $BaTi_4O_9$ thin film grown at $550^{\circ}C$ and rapidly thermal annealed at $900^{\circ}C$ was about 40 at low frequency range($100kHz{\sim}1MHz$) and 36 at microwave range($1{\sim}10GHz$) which is very close to that of the bulk $BaTi_4O_9$ phase. The dissipation factor was very low, about 0.005 at low frequency as well as microwave range.

• Steel and Composite Structures
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• v.32 no.2
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• pp.199-212
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• 2019

This paper presents an investigation on seismic behavior of out-of-code Q690 circular high-strength concrete-filled thin-walled steel tubular (HCFTST) columns made up of high-strength (HS) steel tubes (yield strength $f_y{\geq}690MPa$). Eight Q690 circular HCFTST columns with various diameter-to-thickness (D/t) ratios, concrete cylinder compressive strengths ($f_c$) and axial compression ratios (n) were tested under the constant axial loading and reversed cyclic lateral loading. The obtained lateral load-displacement hysteretic curves, energy dissipation, skeleton curves and ductility, and stiffness degradation were analyzed in detail to reflect the influences of tested parameters. Subsequently, a simplified shear strength model was derived and validated by the test results. Finally, a finite element analysis (FEA) model incorporating a stress triaxiality dependent fracture criterion was established to simulate the seismic behavior. The systematic investigation indicates the following: compared to the D/t ratio and axial compression ratio, improving the concrete compressive strength (e.g., the HS thin-walled steel tube filled with HS concrete) had a slight influence on the ductility but an obvious enhancement of energy dissipation and peak load; the simplified shear strength model based on truss mechanism accurately predicted the shear-resisting capacity; and the established FEA model incorporating steel fracture criterion simulated well the seismic behavior (e.g., hysteretic curve, local buckling and fracture), which can be applied to the seismic analysis and design of Q690 circular HCFTST columns.

• Electrical & Electronic Materials
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• v.9 no.5
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• pp.455-462
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• 1996

Automobile Fuel Shortage Detecting Sensor, in this paper, was fabricated by using heat dissipation coefficient difference between gasoline and air condition the NTC thermistor of Mn-Ni Co system with the composition ratio of Mn$_{3}$O$_{4}$ : 9wt%, NiO : 28wt%, and CO$_{3}$O$_{4}$ : 61wt%. The condition of sensor operation is that, for turn-on characteristics, the time of arriving at 135mA must be less than 180 second when the DC voltage of 11V is applied in the air condition of -10.deg. C and that, for turn-off characteristics, the saturation current must be less than 60mA when the DC voltage of 15V is applied in the gasoline condition of 60.deg. C. It is known, from the experimental results, that the resistance range and B-constant for the Automobile Fuel Shortage Detecting Sensor with dimension of 5*3*0.9mm were 850-1150.ohm. and 1150-1250.deg. C, respectively and the resistance range and B-constant were agree with that of sensor operation condition. When Bi$_{2}$O$_{3}$ of 0-0.5wt% was added to Mn$_{3}$O$_{4}$ : 9wt%, NiO : 28wt%, and CO$_{3}$O$_{4}$ : 61wt% composition, the resistivity and B-value were 380-430(.ohm.-cm) and 1930 - 2030, respectively. Particularly, for Bi$_{3}$O$_{3}$ of 0.25-0.5wt%, the sintering density of over 90% and the operation characteristics necessary to Automobile Fuel Shortage Detecting Sensor were obtained. The difference of heat dissipation coefficient gasoline and air condition was 15 times.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.2
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• pp.73-78
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• 2010

Wave energy is dissipated mainly by friction on the seabed until the waves reach the surf zone. Many researchers have investigated the mechanism of wave friction and the bottom shear stress induced by wave motion at a certain point is now well estimated by introducing the wave friction factor related to the near bed velocity given by linear wave theory. The variation of wave energy or wave height over a long distance can be, however, estimated by an iteration process when the propagation of waves is strongly influenced by bed friction. In the present study simple semi-theoretical equation has been developed to compute the variation of wave height for the condition of wave propagation on a constant beach slope. The ratio of wave height is determined by the product of shoalng factor and wave height friction factor (frictional wave energy dissipation factor). The wave height estimated by the new equation is compared with the wave height estimated by the solution of numerical integration for the condition that the waves propagate on a constant slope.

• Korean Journal of Environmental Agriculture
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• v.41 no.3
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• pp.153-157
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• 2022

BACKGROUND: The residue dissipation pattern of pesticides for agricultural products during the pre-harvest period after the final application is important to prevent the maximum residue limit (MRL) violations in domestic and export markets. The MRL violations of carbendazim are observed more often in chamnamul by pesticide residue management surveys by the Ministry of Food and Drug Safety. The residue level at the pre-harvest interval (PHI) and the residue dissipation constant from the critical good agricultural practice (cGAP) trials could be estimated to meet the MRL and pose a health risk to consumers. METHODS AND RESULTS: Chamnamuls were harvested at 0, 1, 3, 5, 7, 10, and 14 days after application of carbendazim in accordance with critical GAP. The residue analysis in chamnanul was performed by HPLC-DAD with the C₁₈ column. The limit of quantitation of carbendazim was 0.04 mg/kg, and the recoveries were 74.4 - 95.8% at the two spiked levels (LOQ and 10LOQ) of carbendazim. The dissipation rates in chamnamul were calculated from the residues at the sampling days by statistical method at a 95% confidence level. The biological half-lives of residual carbendazim in the field trials 1 and 2 were 4.9 and 4.4 days, respectively. CONCLUSION(S): In this dissipation study, the residue concentrations at the recommended PHI were higher than the established MRL in Korea. Therefore, the MRL is proposed based on the residue data sets from the trials conducted at the same cGAP and the dietary exposure assessment.

• Earthquakes and Structures
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• v.12 no.2
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• pp.201-211
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• 2017

This paper experimentally investigates the effect of yield strength of reinforcing bars and stirrups on the seismic performance of reinforced concrete (RC) circular piers. Reversed cyclic loading tests of nine-large scale specimens with longitudinal and transverse reinforcement of different yield strengths (varying between HRB335, HRB500E and HRB600 rebars) were conducted. The test parameters include the yield strength and amount of longitudinal and transverse reinforcement. The results indicate that the adoption of high-strength steel (HSS) reinforcement HRB500E and HRB600 (to replace HRB335) as longitudinal bars without reducing the steel area (i.e., equal volume replacement) is found to increase the moment resistance (as expected) and the total deformation capacity while reducing the residual displacement, ductility and energy dissipation capacity to some extent. Higher strength stirrups enhance the ductility and energy dissipation capacity of RC bridge piers. While the product of steel yield strength and reinforcement ratio ($f_y{\rho}_s$) is kept constant (i.e., equal strength replacement), the piers with higher yield strength longitudinal bars are found to achieve as good seismic performance as when lower strength bars are used. When higher yield strength transverse reinforcement is to be used to maintain equal strength, reducing bar diameter is found to be a better approach than increasing the tie spacing.