• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1990.10a
• /
• pp.31-35
• /
• 1990

In the ($Bi_{1-x}Pb_{x}$)$_2$$Sr_2$$Ca_2$$Cu_{3.6}$$O_{y}$ (x=0∼0.5) superconductors, DTA and XRD-pattern analyses were performed to obviousely define optimal calcining and sintering temperature. And, understanding behaviors of High-Tc phase with preparation condition of superconductors, that is, calcining and sintering temperature, sintering time, and variation of Pb contents, in order to make single phase of superconductor, microstructure and its composition were analyzed with SEM, XRD, and EDAX. continuously, the cause of phase transition was define with synthetically studying mutural relation between measured electrical resistivity and current density. Also, in order to design enhancement of critical current density, Jc required for realization, samples varied with pressing condition were made, and measured its, Jc.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.129-136
• /
• 1997

The automated ball indentation(ABI) test was utilized to develop a semi-nondestructive method for estimating the fracture toughness( $K_{JC}$ ) in the transition temperature range. The key concept of the method is that the indentation deformation energy to the load at which the mean ball-specimen contact pressure reaches the fracture stress is related to the fracture energy of the material. ABI tests were performed for the reactor pressure vessel(RPV) base and weld metals at the temperatures of-15$0^{\circ}C$~$0^{\circ}C$ and the fracture toughness (estimated $K_{JC}$ ) was calculated from the indentation load-depth data. For all steels the temperature dependence of the estimated fracture toughness was almost the same as that ASTM $K_{JC}$ master curve The reference temperatures( $T_{o}$)of the steels were determined form the estimated $K_{JC}$ versus temperature curves. The reference temperature was well correlated with the index temperature of 41J Charpy impact energy( $T_{41J}$).).).

• International Journal of Computer Science & Network Security
• /
• v.22 no.7
• /
• pp.347-351
• /
• 2022

Farmers E-Market is a website that allows agricultural workers to direct market their products to buyers without the use of a middleman. That theory is blockchain system will be used by authors to accomplish this. The system, which is built on a public blockchain system, supports sustainability, shippers, and consumers. Farmers can keep track of their farming activities. Customers can review the product's history and track its journey through carriers to delivery after making a purchase. Farmers are encouraged to get information about their interests promptly in a blockchain-enabled system like this. This functionality is being used by small-scale farmers to form groups based on their location to attract large-scale customers, renegotiate farming techniques or volumes, and enter into contracts with buyers. The analysis shows the use of blockchain technology with a farmer's portal that keeps the video of trading data of crops, taking into account the qualities of blockchain such as values and create or transaction data. The proposal merges python as a programming language with a blockchain system to benefit farmers, vendors, and individuals by preserving transactions.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.11
• /
• pp.1028-1034
• /
• 1998

Bi-2223 superconductor is known as one of the candidates for practical superconducting wires. Ag-sheathed Bi-2223 superconducting wires were fabricated using the powder-in-tube(PIT) method. When the 19-filaments wire was immersed in liquid nitrogen(77K), maximum critical current density Jc of 62 A/$mm_2$ at 0T was achieved. The critical current density has been shown to depend on the mechanical properties such as tensile stress and bending strain in Ag-sheathed Bi-2223 superconducting wires. The tensile strain for Jc degradation onset was in the range of 0.12~0.3%. In the case of 19-filaments wire, the bending strain is estimated to be smaller than 0.3% for the reasonable Jc value. The observed degradation of the critical current density due to strain effect is inevitable and can be attributed to the formation of microcracks within the superconducting core.

• Microbiology and Biotechnology Letters
• /
• v.23 no.2
• /
• pp.187-196
• /
• 1995

In order to produce fuctional chitooligosaccharides, a strain excreting mainly endo-type chitinase suitable for chitooligosaccharides production was newly screened and identified as Aspergillus fumigatus JC-19. The chitinase excretion was repressed in nutrient rich medium but stimulated by colloidal chitin indicating that the chitinase is inducible type enzyme. Maximum secretion of the enzyme was observed at pH 7.0 and 37$\circ$C . The growth and chitinase production patterns of Aspergillus fumigatus JC-19 showed that the cell growth reached maximum after 4-5 days with final chitinase concentration of 0.46 unit per ml. Excreted chitinase was purified by ammonium sulfate precipitation, colloidal chitin adsorption, anion exchange chromatography, and gel filtration, respectively, and measured M.W of 50 KDa. The enzyme reaction carried out both by crude and purified chitinase showed that the purified chitinase accumulated more chitooligosaccharides of 1-6 degree of polymerization than that of crude chitinase.

• Journal of the Chungcheong Mathematical Society
• /
• v.19 no.2
• /
• pp.159-175
• /
• 2006

This paper is a survey on the Hyers-Ulam-Rassias stability of the Jensen functional equation in $C^*$-algebras. The concept of Hyers-Ulam-Rassias stability originated from the Th.M. Rassias' stability theorem that appeared in his paper: On the stability of the linear mapping in Banach spaces, Proc. Amer. Math. Soc. 72 (1978), 297-300. Its content is divided into the following sections: 1. Introduction and preliminaries. 2. Approximate isomorphisms in $C^*$-algebras. 3. Approximate isomorphisms in Lie $C^*$-algebras. 4. Approximate isomorphisms in $JC^*$-algebras. 5. Stability of derivations on a $C^*$-algebra. 6. Stability of derivations on a Lie $C^*$-algebra. 7. Stability of derivations on a $JC^*$-algebra.

• Structural Engineering and Mechanics
• /
• v.9 no.3
• /
• pp.257-268
• /
• 2000

The seismic design recommendations of the Jordan Code for Loads and Forces (JC) are evaluated, based on comparisons with analytical studies and the Uniform Building Code. It was established that the overall safety ensured by the implementation of these recommendations is not consistent with the established seismic risk in Jordan and the intended objectives of the code. A new zoning map is proposed with effective peak ground acceleration values. The different period formulae of the code were studied and were found to grossly underestimate the fundamental period when compared with analytically derived values or other codes' formulae. Other factors including the dynamic, soil, importance and behavior factors are discussed. It was determined that the JC's lateral load distribution formulae clearly lead to smaller internal forces than both dynamic analysis and UBC loads, even when those loads are normalized to give the same base shear. The main reason for this is attributed to the limited allowance for a backlash force in the JC.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2002.09a
• /
• pp.35-42
• /
• 2002

Frequency responses for most of the local seismic sensors in Korea have been roughly checked by mutual comparison of Fourier spectra of seismic records from accelerometer and seismometer, both of which are installed at the same location. Especially, because the frequency content of the seismic energy is usually above 1 Hz for local earthquakes, the reliability of low frequency response could have not been evaluated. Fortunately a recent large earthquake, Ms=7.2 on 02/06/29 containing dominant low frequency energy makes it possible to check the low frequency response of the seismic sensors, especially EpiSensor and JC-V100. Considering two types of sensor pairs, (STS-2 and EpiSensor, JC-V100 and EpiSensor), the low frequency response of EpiSensor is confirmed first by comparison with STS-2 which has proved low frequency response. Second, reliable low frequency limit of instrumentally corrected seismic data from JC-V100 data is estimated to be about 0.03 Hz by comparison with EpiSensor data.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.5C no.5
• /
• pp.217-220
• /
• 2005

We have fabricated a superconducting YBCO system according to the pyrolysis method and low pressure apparatus. In our experiment, the X-ray diffraction pattern of the non doped YBaCuO layer indicated that the superconductor contained only 90K phase crystal. The critical temperature and critical current density for a thick layer at $650^{\circ}C$ were Tc=90 K and $Jc=6{\times}10^{4}A/cm^2$ at 90K. In low pressure apparatus, the 90 K phase YBaCuO was grown at a lower temperature compared with the normal system. Tc and Jc at $650^{\circ}C$ were Tc = 90 K and $Jc=6{\times}10^{4}A/cm^2$ at 90K.

• Korean Journal of Materials Research
• /
• v.27 no.1
• /
• pp.19-24
• /
• 2017

This paper is concerned with a test method that can be used to investigate the parameters of the Johnson-Cook constitutive model. These parameters are essential for accurately analyzing material behavior under impact loading conditions in numerical simulation. Ti-6Al-4V alloy (HCP crytal structure) was used as a specimen for the experiments. In the $10^{-3}-10^3/s$ strain rate range, three types of experimental methods (convention, compression and tension) were employed to compare the differences using MTS-810, SHPB and SHTB. Finite element analysis results when applying these parameters were displayed along with the experiment results.