• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1059-1060
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• 2006

The creep behavior of Al-5vol.% SiC composite was investigated. The composite powder was produced by mechanical milling and hot extruded at $450^{\circ}C$ at ratio of 16:1. A creep test was carried out at a constant load at 598, 648, and 673 K. Using the steady-state equations, the threshold stress and the stress exponent of the creep as a function of temperature were determined. The stress exponent was found to be 3 at the temperature of 673 K and 8 at 598 and 648 K. The dependency of the threshold stress to temperature obeys the Arrhenius relationship with the energy term of $29\;kJ\;mole^{-1}$.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.4
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• pp.351-359
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• 2002

In this paper, stochastically dependent single and sequential acceptance sampling plans are dealt when the process follows a Polya process model. A Monte-Cairo algorithm is used to find the acceptance and rejection probabilities of a lot. The number of defectives for the test to be accepted and rejected in a probability ratio sequential test can be found by using these probabilities. The formula to measure performance of these sampling plans is developed. Type I and II error probabilities are estimated by simulation. Dependent multiple acceptance sampling plans can be derived by extending the sequential sampling procedure. In numerical examples, single and sequential sampling plans of a Polya dependent process are examined and the characteristics are compared according to the change of the dependency factor.

• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.198-202
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• 1998

We have studied $Al_xFe_{3-x}O_4$ produced by direct composition method using X-ray diffraction and Mssbauer spectroscopy. The cation distribution for $Al_xFe_{3-x}O_4$ was determined by the ratio of sub-spectra absorption area. The charge state of Fe atoms in octahedral site(B-site) is $Fe^{2.5+}$ based on electron hopping, $Fe^{2+}$ ↔ $(Fe^{3+},Al^{3+})$ without dependency of substituted Al amounts.

• Korea Journal of Hospital Management
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• v.4 no.2
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• pp.305-329
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• 1999

Financial ratio indicators of the 46 sample hospitals provided by the Korea Health Industry Development Institute, together with the survey data responded by the 57 sample hospitals, were analysed to identify the characteristics of the red-figured hospitals' financial structure, financial operational efficiency and management decision-making behavior, The financial characteristics identified through the analysis include high dependency to liabilities, high salary expenses and overhead costs, low profitability of the unduly large amount of fixed assets, and low managerial efficieny of inventory. The hospitals, in face of the IMF economic impasse, took the necessary decision-making and counter measures to cut down salary expenses, to increase the number of patient and medical revenue, and to reduce investment to fixed assets. Based on these findings this study suggested that the hospitals should take more active cost containment measures, financial structural reorganization, and developoment of the strategies that can contribute to increase of the number of patient and medical revenue and that do not. require much capital funds.

• Journal of Communications and Networks
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• v.6 no.2
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• pp.182-191
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• 2004

In this paper, performances of different ultra-wideband (UWB) modulation schemes in the presence of timing jitter are evaluated and compared. Static and Rayleigh fading channels are considered. For fading channels, Oat and dispersive channels are assumed. First, bit error rate (BER) performances for each case are derived for a fixed value of timing jitter. Later, a uniform distribution of jitter is assumed to evaluate the performance of the system, and the theoretical results are verified by computer simulations. Finger estimation error is treated as timing jitter and an appropriate model is generated. Furthermore, a worst case distribution that provides an upper bound on the system performance is presented and compared with other distributions. Effects of timing jitter on systems employing different pulse shapes are analyzed to show the dependency of UWB performance on pulse shape. Although our analysis assumes uniform timing jitter, our framework can be used to evaluate the BER performance for any given probability distribution function of the jitter.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1568-1569
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• 2007

TFT-LCD used in display area is not a light-emissive device itself but TFT-LCD can overcome through the employ of the backlight unit (BLU). BLU is very important device in TFT-LCD system. However, the old-fashion BLU of CCFL type is crucible to the health due to the contained material, mercury (Hg). Moreover, strong temperature dependency of lamp employed with Hg becomes the other disadvantage in practical usage. To solve these problems, Hg-Free lamp with strong thermal resistance property is required to displace the Hg lamp. We studied optical and electrical properties of Xe-Ne-He mixed gas that is dependent on change of mixed ratio and pressure. In our results, the designed lamp without the phosphorescent material has the lowest firing voltage at xe 50%(Ne:He=9:1).

• Computers and Concrete
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• v.21 no.6
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• pp.741-748
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• 2018

In this paper, the sensitivity of a plastic-damage-based structural damage index on mesh density is studied. Multiple finite element meshes with increasing density are used to investigate their effect on the damage index values calculated from nonlinear finite element simulations for a reinforced concrete column subjected to cyclic loading. With the simulation results, this paper suggests a correction method for the objective damage index based on nonlinear regression of volumetric tensile damage ratio data. The modified damage index values are presented in the quasi-static cyclic simulation to show the efficacy of the suggested correction method.

• Journal of Multimedia Information System
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• v.5 no.4
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• pp.273-276
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• 2018

In video compression standards, the entropy coding is essential to the high performance compression because redundancy of data symbols is removed. Binary arithmetic coding is one of high performance entropy coding methods. However, the dependency between consecutive binary symbols prevents improving the throughput. For the throughput enhancement, a new probability model is proposed for encoding multi-symbols at one time. In the proposed method, multi-symbol encoder is implemented with only adders and shifters, and the multiplication table for interval subdivision of binary arithmetic coding is removed. Compared to the compression ratio of CABAC of H.264/AVC, the performance degradation on average is only 1.4% which is negligible.

• Advances in aircraft and spacecraft science
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• v.6 no.3
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• pp.207-223
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• 2019

Current investigation deals with the thermal stability characteristics of carbon nanotube reinforced composite beams (CNTRC) on elastic foundation and subjected to external uniform temperature rise loading. The single-walled carbon nanotubes (SWCNTs) are supposed to have a distribution as being uniform or functionally graded form. The material properties of the matrix as well as reinforcements are presumed to be temperature dependent and evaluated through the extended rule of mixture which incorporates efficiency parameters to capture the size dependency of the nanocomposite properties. The governing differential equations are achieved based on the minimum total potential energy principle and Euler-Bernoulli beam model. The obtained results are checked with the available data in the literature. Numerical results are supplied to examine the effects of numerous parameters including length to thickness ratio, elastic foundations, temperature change, and nanotube volume fraction on the thermal stability behaviors of FG-CNT beams.

• Journal of the Semiconductor & Display Technology
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• v.20 no.2
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• pp.82-86
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• 2021

In this study, we investigated the oxygen partial pressure effect of ITO films for electrodes of oxide-based Thin-Film Transistor (TFT). Firstly, we deposited single ITO films on the glass substrate at room temperature. ITO films were prepared at the various partial pressures of oxygen gas 0-7.4% (O₂/(Ar+O₂)). As increasing oxygen on the process of film deposition, electrical properties were improved and optical transmittance increased in the visible light range (300-800 nm). For the electrode of TFT, we fabricated a TFT device (W/L=1000/200 ㎛) with ITO films as the source and drain electrode on the silicon wafer. Except for the TFT device combined with ITO film prepared at the oxygen partial pressure ratio of 7.4%, We confirmed that TFT devices with ITO films via FTS system operated as a driving device at threshold voltage (V_th) of 4V.