• Resources Recycling
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• v.12 no.1
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• pp.55-64
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• 2003

Presently, the reuse of waste FCC catalysts, which generated from the refining process of crack oil, after the removal of con-taminated metallic impurities have not been attempted domestically yet because the separation technology f3r the impurities from waste catalysts has not been established. As a basic study far the reusable portion from the waste FCC catalysts and treatment of metallic impurities are assured, there will be invoked an significant contribution not only in the recycling of abandoned wastes up to date but also in the treatment efficiency of wastes and extraction of economical benefits from them. The magnetic separation of impurities such as Fe, Ni, and V, from waste FCC catalyst has been attempted with or without its pre-oxidation at high temperature for the purpose of its reuse. The results showed that the separability of impurities by magnetic force was high far non-preoxidized catalysts compared with preoxidized ones, and employment of screen-type matrix showed a higher separation efficiency than ball-type matrix. The separability increased with the strength of magnetic field, and the method of ball matrix has separation efficiency of maximum 51.10%. The amount of metallic impurities was in the decreasing order of V, Ni, and Fe depending upon ICP analysis.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.1
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• pp.1-7
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• 2017

Most conventional processors execute program instructions in a sequential manner. On the other hand, VLIW processor can execute multiple instructions at the same time. It exploits instruction level parallelism to improve system performance. To that end, program code should be rearranged to VLIW instruction format by a compiler. The compiler determine an optimal execution order of instructions of a program code. This instruction ordering is also called instruction scheduling. The scheduling is an algorithm that decides the execution order for instruction codes in loop parts of a program so that the instruction level parallelism can be maximized. In this research, we apply an existing scheduling algorithm to a VLIW FCC and describe analysis results to further improve its performance. And, we present a solution to solve some limitation of the existing scheduling technique. By using our solution, FCC's performance can be improved upto 32% compared to the existing scheduling only setting.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.516-521
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• 2005

The application of UWB not only complies with the requirements of remote sensors system(ECG), it also contributes to the effectiveness of the implementations through its unique qualities such as ultra low transmission power - an important factor when dealing with biomedical equipment. In this paper, the aim is to replace the wired ECG sensors with a wireless link and design wireless UWB communication system. The various pulse shapes are presented that satisfies the FCC spectral mask and FCC part 15 rule. It is shown that UWB can be a high rate transmission over short ranges using Rake receiver, with the capability for reliably transmitting 100Mbps over distance at about 10 meters.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.137-143
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• 2006

The effects of Cu and Fe additions on the thermal stability, microstructure and mechanical properties of $Al_{85}-Ni_{8.5}-Mm_{6.5},\;Al_{84}-Ni_{8.5}-Mm_{6.5}Cu_1,\;Al_{84}-Ni_{8.5}-M_{m6.5}Fe_1$ alloys, manufactured by gas atomization, degassing and hot-extrusion were investigated. Gas atomization, with a wide super-cooled liquid region, allowed the alloy powders to exhibit varying microstructure depending primarily on the powder size and composition. Al hotextruded alloys consisted of homogeneously-distributed fine-grained fcc-Al matrix and intermetallic compounds. A substitution of 1 at.% Al by Cu increased the thermal stability of the amorphous phase and produced alloy microstructure with smaller fcc-Al grains. On the other hand, the same substitution of 1 at.% Al by Fe decreased the stability of the amorphous phase and produced larger fcc-Al grains. The formation of intermetallic compounds such as $Al_3Ni,\;Al_{11}Ce_3\;and\;Al_{11}La_3$ was suppressed by the addition of Cu or Fe. Among the three alloys examined, the highest Vickers hardness and compressive strength were obtained for $Al_{84}-Ni_{8.5}-M_{m6.5}Cu_1$ alloy, and related to the finest fcc-Al grain size attained from increased thermal stability with Cu addition.

• Journal of Magnetics
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• v.13 no.4
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• pp.144-148
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• 2008

The size and surface effects on the magnetism of a fcc Fe (001) surface was investigated by performing firstprinciples calculations on 3, 5, 7, and 9 monolayers fcc Fe (001) single slabs with two different two-dimensional lattice constants, ${\alpha}=3.44{\AA}$ (System I) and 3.65 ${\AA}$ (System II), using the all-electron full-potential linearized augmented plane wave method within a generalized gradient approximation. The surface layers were coupled ferromagnetically to the subsurface layer in both systems. However, the magnetism of the inner layers was quite different from each other. While all the inner layers of System II were ferromagnetically coupled in the same way as the surface layer, the inner layers of System I showed a peculiar magnetism, bilayer antiferromagnetism. The calculated spin magnetic moments per Fe atom were approximately 2.7 and 2.9 ${\mu}_B$ at the surface for Systems I and II, respectively, due to the almost occupied Fe d-state being in the majority spin state and band narrowing. The spin orientations of System I were out-of-plane regardless of its thickness, whereas the orientation of System II changed from out-of-plane to in-plane with increasing thickness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.3A
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• pp.157-165
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• 2003

The purpose of this paper is to analyze the performance requirements of wireless systems on ultra wide band, which is set by FCC(Federal Communications Commission). Normally the calculation of performance requirements is used in the standard form of each communication systems, but there is no standard in the wireless systems on Ultra WideBand. Therefore, I derive each system parameters through the analysis of new system performance on the basis of the method of Indoor Communication Systems. Additionally, I compare the conditions that are given by FCC with resolution of the performance by domestic law.

• Journal of Magnetics
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• v.12 no.1
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• pp.45-48
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• 2007

[ $Co_{100-X}Zr_X$ ] (x=10-40) alloys were prepared by using a mechanical alloying technique. Phase constitution of the crystallised material depended on the annealing temperature. The $Co_{82}Zr_{18}$ alloy crystallised at lower temperature around $550^{\circ}C$ consisted of $Co_{23}Zr_6$, $Co_5Zr$ and fcc-Co phases, while the alloy crystallised at higher temperature around $800^{\circ}C$ consisted of $Co_{23}Zr_6$ and fcc-Co phases. Phase constitution of the crystallised material also depended on the chemical composition of the alloy. The material with lower Zr content less than 10 at% Zr consisted of $Co_{23}Zr_6$ and fcc-Co, and the material with higher Zr-content over 30 at% consisted of $Co_2Zr$ phase. The material containing 15-20 at% Zr consisted of $Co_{23}Zr_6$, $Co_5Zr$ and fcc-Co. Only the material containing $Co_5Zr$ phase exhibited substantial coercivity, and it was confirmed that coercivity in the mechanically alloyed Co-Zr alloy was originated from the $Co_5Zr$ phase.

• Nuclear Engineering and Technology
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• v.52 no.2
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• pp.344-351
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• 2020

AgInCd alloy is widely used as neutron absorber in nuclear reactors. However, the AgInCd control rods may fail during service due to the irradiation swelling. In the present study, a calculational method is proposed to calculate the composition change of the AgInCd absorber. Calculated results show that neutron fluence has significant impact on the chemical compositions. Ag and In contents gradually decrease while Cd and Sn conversely increases from the center to the rim of AgInCd absorber due to the depression of neutron flux. The composition change at the surface is higher almost two times than that at the center. Based on the calculated compositions, six simulated AgInCdSn alloys were prepared and examined. With the increase of Cd and Sn, the simulated AgInCdSn alloys transform from a single fcc phase into the mixed fcc and hcp phases, and finally into the single hcp phase. The atomic volume of the hcp phase is obviously larger than the fcc phase. The fcc-hcp transformation results in considerable volume swelling of the AgInCd absorber. Moreover, the lattice parameters of the fcc and hcp phases gradually increase with Cd and Sn contents, which also can induce small volume swelling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8A
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• pp.633-643
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• 2003

UWB impulse radio signals have an very short duration, extremely wide bandwidth and share the same frequency spectrum with other existing systems. It was determined by the Federal Communications Commission (FCC) that UWB systems could cause interference with other systems, such as Global Positioning System (GPS) for example. Therefore, at present. the FCC has restricted the use of UWB systems to frequencies above 3.1㎓. In this paper, We evaluated performance of UWB system using proposed pulses in ［1］［2］ that are strictly limited in time to remove interference while, at the same time, contain their power distribution to a frequency band from 3.1㎓ to 10.6㎓. In particular, We evaluated the BER Performance in relation to system parameters such as pulse duration. $\delta$, the number of users. Nu. and the number of symbols, M. We found the optimal pulse duration $\delta$ through computer simulation using developed UWB pulses in ［1］［2］. It is shown that performance evaluation between the UWB communication system using these UWB pulses ［1］［2］and the Gaussian monocycle pulse in M-ary PPM and BPSK schemes. These results can be contributed to construct M-ary PPM UWB communication system in terms of multiuser parameters and pulse duration.

• Journal of Communications and Networks
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• v.5 no.4
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• pp.344-353
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• 2003

Ultra-wideband (UWB) technology is gaining increasing interest for its potential application to short-range indoor wireless communications. Utilizing ultra-short pulses, UWB baseband transmissions enable rich multipath diversity, and can be demodulated with low complexity receivers. Compliance with the FCC spectral mask, and interference avoidance to, and from, co-existing narrow-band services, calls for judicious design of UWB pulse shapers. This paper introduces pulse shaper designs for UWB radios, which optimally utilize the bandwidth and power allowed by the FCC spectral mask. The resulting baseband UWB systems can be either single-band, or, multi-band. More important, the novel pulse shapers can support dynamic avoidance of narrow-band interference, as well as efficient implementation of fast frequency hopping, without invoking analog carriers.