• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1990.10a
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• pp.71-77
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• 1990

This paper is studied on the sintering characteristics of Ni-Zn ferrites. The specimen ferrites was composed of 20 mol% NiO, 30mol% ZnO, 50 mol% Fe$_2$O$_3$, and 0.0025 mol%, 0.005 mol%, 0.01 mol% Nb$_2$O$\_$5/, Bi$_2$O$_3$, V$_2$O$\_$5/, wee used as minor additives. Sintering was carried out at 1100$^{\circ}C$. As results from the experiments, the high value of initial permeability of 6X10$^2$∼9X10$^2$ can be achieved at 500KHz∼1000KHz. The value of loss factor 1X10￣$^2$∼2X10$^2$ can be achieved at 500KHz∼1000KHz. The lowest 1/(${\mu}$XQ) value was obtained in the specimen with the addition of 0.005mol% fracyion for V$_2$O$\_$5/.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.251-254
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• 2000

This paper was to measure the structure, electric characteristics of 0.05Pb($(Al_{0.5}Nb_{0.5})$) - 0.95Pb$(Zr_{0.52}Ti_{0.48})O_3$ ceramics dopped with Cr+Fe. The results of this paper were gotten such as follows; The dielectric constants were decreased with Cr+Fe. The dielectric loss was minimum value of 1.008[%], dopped with Cr+Fe O.9[wt%] at 1200[$^{\circ}C$], In case of sintering at 1150[$^{\circ}C$], electromechanical factodkp) was maximum value of kp 42.73[%], at Cr+Fe 0.9[wt%]. The mechanical quality factor(Qm) was maximum value at Cr+Fe 1.2 [wt%], Also, in case of dopped with Cr+Fe, it make a improvement in temperature coefficient of resonant frequency at 0.3[wt%], 1150[$^{\circ}C$].

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.2
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• pp.119-122
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• 2009

As infrared light radiates, the CMOS Readout IC (ROIC) for the microbolometer typed infrared sensor detects voltage or current which is caused by the variation of resistance in the bolometer sensor. A serious problem we may have in designing the ROIC is the value of bolometer and reference resistors will be changed due to process variation. Since each pixel does not have the same value of resistance, fixed pattern noise problems happen during the sensor operations. In this paper, we propose a novel technique to compensate the fluctuation of reference resistance with taking account of process variation. By using a comparator and a cross coupled latch, we will make the value of reference resistor same as the bolometer's.

• Proceeding of EDISON Challenge
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• 2015.03a
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• pp.285-291
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• 2015

In this paper, a composite material analysis program based on the finite element method(FEM) is used. The purpose of this study was to verify whether the composite material analysis program which developed as part of a project of development of softwares and educational contents for structural vibration and composite material analysis that can calculate how similar the macroscopic mechanical behavior of the composite materials actually. Because composite materials are generally anisotropic, analysis of composite laminate is used for the constitutive equations of orthotropic material. For convenience, the unit is ommited in all calculations. To verify the accuracy of the finite element method based program, the deflection and stress distribution of the simply supported composite material laminated plate subjected to a uniform load distribution is compared with exact solution. Size and properties of the composite material laminate used for analysis are fixed variables, and by changing the number of elements and the total thickness of the laminate is compared with the exact solution to the resulting value, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.97-100
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• 1996

In this paper, 3-terminal EMI filter for communication was studied. EMI filter for communication combining Ferrite bead with 3-terminal capacitor was constructed with T-type. We was able to control resonance frequency with chip capacitor value and attenuation characteristics by Ferrite bead properties.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1983.04a
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• pp.45-47
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• 1983

In integrated circuit, for a saving in total chip area per circuit, stably high value resistor was fabricated. Hence this paper explained that the measurement and fabrication of high value semiconductor resistor using ITO thin film. It is also used special material and new method fabrication.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.2
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• pp.313-330
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• 1993

The propagating crack problems under dynamic plane mode in orthotropic material is studied in this paper. To analyze the dynamic fracture problems in orthortropic material, it is important to know the dynamic stress components and dynamic displacement components around the crack tip. Therefore the dynamic stress components of dynamic stress field and dynamic displacement components of dynamic displacement field in the crack tip of orthotropic material under the dynamic load and the steady state in crack propagation were derived. When the crack propagation speed approachs to zero, the dynamic stress component and dynamic displacement components derived in this study are identical to the those of static state. In addition, the relationships between dynamic stress intensity factor and dynamic energy release rate are determinded by using the concept of crack closure closure energy with the dynamic stresses and represented according to physical properties of the orthotrophic material and crack speeds. The faster the crack velocity, the greater the stress value of stress components in crack tip. The stress value of the stress component of crack tip is greater when fiber direction coincides with the crack propagation than when fider direction is normal to the crack propagation.

• Advances in concrete construction
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• v.6 no.1
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• pp.15-28
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• 2018

In the present investigation, influence of various material parameters on the cavitation erosion resistance of concrete was investigated on the basis of laboratory experiments. As there is no well-established laboratory test method for evaluating the cavitation resistance of concrete, a test set up called 'cavitation jet' was specially established in the present study in order to simulate the cavitation phenomenon experienced in the hydraulic structures. Various mixtures of concrete were designed by varying the grade of concrete, type and quantity of pozzolana, type of aggregates and cement type to develop good cavitation resistant concrete constructed using marginal aggregates. Three types of aggregates having three different Los Angeles abrasion values (less than 30%, between 30% and 50% and more than 50%) were employed in this study. To evaluate the cavitation resistance a total of 60 cylindrical specimens and 60 companion cubes were tested in the laboratory respectively. The results indicate that cavitation resistance of concrete degrades significantly as the L.A. abrasion value of aggregates goes beyond the 30% value. Incorporation of pozzolanic admixtures was seemed to be beneficial to enhance the cavitation resistance of concrete. Influence of other material parameters on the cavitation resistance of concrete was also noted and important observations have been made in the paper.

• Nuclear Engineering and Technology
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• v.53 no.3
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• pp.911-919
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• 2021

In this paper, the design stress intensity values for the plate-type fuel assembly for research reactor are presented. Through a tensile test, the material properties of the cladding (aluminum alloy 6061) and structural material (aluminum alloy 6061-T6), in this case the yield and ultimate tensile strengths, Young's modulus and the elongation, are measured with the temperatures. The empirical equations of the material properties with respect to the temperature are presented. The cladding undergoes several heat treatments and hardening processes during the fabrication process. Cladding strengths are reduced compared to those of the raw material during annealing. Up to a temperature of 150 ℃, the strengths of the cladding do not significantly decrease due to the dislocations generated from the cold work. However, over 150 ℃, the mechanical strengths begin to decrease, mainly due to recrystallization, dislocation recovery and precipitate growth. Taking into account the uncertainty of the 95% probability and 95% confidence level, the design stress intensities of the cladding and structural materials are established. The presented design stress intensity values become the basis of the stress design criteria for a safety analysis of plate-type fuels.

• Korean Journal of Agricultural Science
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• v.27 no.1
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• pp.54-62
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• 2000

This study was performed to evaluate the food technological properties according to different emulsion state of carthamus red pigment. For making emulsion, lecithin was used as an emulsifier and polyglycerol monooleate(PGMO) and polyoxyethylene sorbitan monooleate(Tween 80) were used as an assistant, and glycerin, distilled water and soybean oil were used as base materials respectively. Paprika stock solution was used for comparing carthamin on the rheological properties. The results were described as following: 1. Hunter L-value was not drastically increased until passed by 8 hours for glycerin, carthamin, and lecithin mixed sample. 2. Hunter a-value was higher at carthamin added sample than others. and b-value was higher to paprika added sample than others. 3. The viscosity, shear rate and shear stress levels in which glycerin was used as base material were higher than soybean oil or distilled water. 4. In which soybean oil was used as base material. lecithin was not affected on the rheological properties. But, in which glycerin was used. the lecithin was higher affected on carthamin than paprika. 5. The value of shear stress was increased both carthamin and soybean oil. However, that of shear rate was shown similar trends.