• Journal of Internet Computing and Services
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• v.9 no.4
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• pp.1-10
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• 2008

In this paper, a packet scheduling algorithm, called the modified PLFS, is proposed for real-time traffic in IEEE 802.22 WRAN systems. The modified PLFS(Packet Loss Fair Scheduling) algorithm utilizes not only the delay of the Head of Line(HOL) packets in buffer of each user but also the amount of expected loss packets in the next-next frame when a service will not be given in the next frame. The performances of the modified PLFS are compared with those of PLFS and M-LWDF in terms of the average packet loss rate and throughput. The simulation results show that the proposed scheduling algorithm performs much better than the PLFS and M-LWDF algorithms.

• Proceedings of the Acoustical Society of Korea Conference
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• 1993.06a
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• pp.109-112
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• 1993

In this paper, we propose the modified VQ, applied correlation between codewords in order to reduce the error rate due to personal and speakers' temporal variation. Such a modified VQ is used in the stage of preprocessing of HMM and the temporal variation is absorbed by nonlinear Decimation and Interpolation of vowel part that we obtain higher recognition rate than not so case. The objects of experiment are Korea 142 DDD regional names and we show that the proposed method increase the recognition rate.

• Journal of Korean Institute of Industrial Engineers
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• v.4 no.1
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• pp.49-55
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• 1978

This paper presents a new method, called a modified economic order quantity method, for determining the optimal inventory policy, which uses the rate of return as its decision criterion. Especially for the simplest possible inventory system with constant demand rate, no backlogging, no lead time, etc., the formula for the optimal order policy is derived. Also mentioned are the relative merits and shortcomings of this method compared to the conventional EOQ model.

• Journal of Intelligence and Information Systems
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• v.3 no.1
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• pp.47-68
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• 1997

This paper discusses a method of modified Elman network(1990) for nonlinear predictions and its a, pp.ication to forecasting daily exchange rate returns. The method consists of two stages that take advantages of both time domain filter and modified feedback networks. The first stage straightforwardly employs the filtering technique to remove extreme noise. In the second stage neural networks are designed to take the feedback from both hidden-layer units and the deviation of outputs from target values during learning. This combined feedback can be exploited to transfer unconsidered information on errors into the network system and, consequently, would improve predictions. The method a, pp.ars to dominate linear ARMA models and standard dynamic neural networks in one-step-ahead forecasting exchange rate returns.

• International Journal of Concrete Structures and Materials
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• v.18 no.3E
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• pp.213-219
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• 2006

Modified singular fracture process zone(S-FPZ) model is proposed in this paper to determine a fracture criterion for continuous crack propagation in concrete. The investigated fracture properties of the proposed fracture model are strain energy release rate at a micro-crack tip and the relationship between crack closure stress(CCS) and crack opening displacement(COD) in the FPZ. The proposed model can simulate the actual fracture energy of experimental results fairly well. The results of the experimental data analysis show that specimen geometry and loading condition did not affect the CCS-COD relation. However, the strain energy release rate is a function of not only specimen geometry but also crack extension. The strain energy release rate remained constantly at the minimum value up to the crack extension of 25 mm, and then it increased linearly to the maximum value. The maximum fracture criterion occurred at the peak load for specimens of large size. The fracture criterion remained at the maximum value after the peak load. The variation of the fracture criterion is caused by micro-cracking and micro-crack localization. The fracture criterion of strain energy release rate can simply be the size effect of concrete fracture, and it can be used to quantify the micro-cracking and micro-crack localizing behavior of concrete.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3353-3370
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• 2016

The way of combination of Product Perfect Codes (PPCs) is based on the theory of short codes constructing long codes. PPCs have larger embedding rate than Hamming codes by expending embedding columns in a coding block, and they have been proven to enhance the performance of the F₅ steganographic method. In this paper, the proposed modified product codes called MPCs are introduced as an efficient way to embed more data than PPCs by increasing 2^r₂-1-r₂ embedding columns. Unlike PPC, the generation of the check matrix H in MPC is random, and it is different from PPC. In addition a simple solving way of the linear algebraic equations is applied to figure out the problem of expending embedding columns or compensating cases. Furthermore, the MPCs over ℤ₄ have been proposed to further enhance not only the performance but also the computation speed which reaches O(n₁+σ). Finally, the proposed ℤ₄-MPC intends to maximize the embedding rate with maintaining less distortion , and the performance surpasses the existing improved product perfect codes. The performance of large embedding rate should have the significance in the high-capacity of covert communication.

• International Journal of Reliability and Applications
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• v.18 no.2
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• pp.21-44
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• 2017

Accelerated life tests (ALTs) are frequently used in manufacturing industries to evaluate the reliability of products within a reasonable amount of time and cost. Test units are subjected to elevated stresses which yield quick failures. Most of the previous works on designing ALT plans are focused on tests that involve a single stress. Many times more than one stress factor influence the product's functioning. This paper deals with the design of optimum modified ramp-stress ALT plan for Burr type XII distribution with Type-I censoring under two stress factors, viz., voltage and switching rate each at two levels- low and high. It is assumed that usage time to failure is power law function of switching rate, and voltage increases linearly with time according to modified ramp-stress scheme. The cumulative exposure model is used to incorporate the effect of changing stresses. The optimum plan is devised using D-optimality criterion wherein the ${\log}_{10}$ of the determinant of Fisher information matrix is maximized. The method developed has been explained using a numerical example and sensitivity carried out.

• Korean Journal of Optics and Photonics
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• v.14 no.2
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• pp.150-154
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• 2003

In this paper, we introduce modified parity coding methods to reduce the errors caused by spatial beam intensity variations in a holographic data storage system. We explained the encoding and decoding process of the conventional parity coding and the modified parity coding techniques. We compared the bit-error-rate (BER) performances of the conventional parity coding and the modified parity coding techniques from experimental evaluation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4B
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• pp.377-382
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• 2011

In this study, hydrogen peroxide is stabilized in modified Fenton reaction to improve the soil remediation. Phenanthrene, which is the typical compound in PAHs, was spiked into soil samples to copy the original contaminated site. Anionic surfactant, SDS (Sodium dodecyl sulfate) was used for hydrogen peroxide stabilizer. 4 mM of Fe(II), 5~50 mM of SDS and 102.897 mM of $H_2O_2$ was injected into soil samples which is contaminated by 125 mg/kg of phenanthrene to analyze decomposition rate of phenanthrene in modified Fenton reaction. In condition which SDS was injected 30 mM, decomposition rate of phenanthrene has best efficiency as 95% and in condition which SDS was injected over 30 mM, decomposition rate is lower than SDS 30 mM because SDS enacted as scavenger in the system. Results which assess the change of hydrogen peroxide concentration after injecting hydrogen peroxide stabilizer showed that hydrogen peroxide concentration was 14.6995 mM so that is stabilized at Fe(II) 2 mM condition in 48 hours. On the other hand, hydrogen peroxide is not stable in Fe(III) condition. SDS concentration was fixed and iron concentration was changed 2~8 mM to find out optimize proportion between iron concentration and SDS concentration in modified Fenton reaction. Consequentially, in condition of which Fe(II) 4 mM and SDS 30 mM, reaction has the highest removal rate as 95%.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.3
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• pp.114-121
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• 2007

In this study, a modified reverse flow type, one of the triple effect absorption cycles, is studied for performance improvement. The cycle simulation is carried out by using EES(Engineering Equation Solver) program for the working fluid of $H_2O/LiBr$ solution. The split-ratios of solution flow rate, UA of each component, pumping mass flow rate of solution are considered as key parameters. The results show that the optimal SRH (split ratio of high side) and SRL (split ratio of low side) values are 0.596 and 0.521, respectively. Under these conditions, the COP is maximized to 2.1. The optimal pumping mass flow rate is selected as 3 kg/s and the corresponding UAEV A is 121 kW/K in the present system. The present simulation results are compared to the other literature results from Kaita's (2002) and Cho's (1998) triple effect absorption systems. The present system has a lower solution temperature and a higher COP than the Kaita's modified reverse flow, and it also gives a higher COP than the Cho's parallel flow by adjusting split ratios.