• Management Science and Financial Engineering
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• v.9 no.1
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• pp.11-27
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• 2003

In this study, we propose a mathematical model based on the graph theory for the wavelength assignment problem arising in the design of SDH (Synchronous Digital Hierarchy) over WDM (Wavelength Division Multiplexing) ring networks. We propose a branch- and -price algorithm to solve the suggested models effectively within reasonable time in realistic SDH over WDM ring networks. By exploiting the structure of ring networks, we developed a polynomial time algorithm for efficient column generation and a branching rule that conserves the structure of column generation. In a computer simulation study, the suggested approach can find the optimal solutions within reasonable time and show better performance than the existing heuristics.

• Journal of Ocean Engineering and Technology
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• v.20 no.4 s.71
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• pp.64-69
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• 2006

A numerical analysis is made to investigate the wave absorption efficiency of a OWC-type wave power generator. Energy absorption by an OWC(Oscillating Water Column) air-chamber is computed in regular waves, taking account of the oscillating surface-pressure, due to pressure drop, across the duct of the air chamber. The problem is formulated in the scope of potential theory and solved by the Localized Finite Element Method(LFEM), based on the classical variational principle. The efficiency of energy absorption is investigated by. changing wave conditions, sea-bottom slope and pressure drop coefficient.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.191-194
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• 2001

The electrokinetic apparatus for remediation of the soil contaminated with Cs$^{+}$was designed. After kaolin clay was compulsorily contaminated by Cs$^{+}$ solution, the remediation characteristics by electrokinetic method were analyzed. After remediation experiment, the pH of the cathode side of the soil column was increased to 12.7 due to the generation of OH in cathode reservoir, but no hydroxide cesium form in the cathode side. Effluent rate from the cathode almost was constant and cesium concentration of effluent decreased with time passage. The 49% of a total of Cs$^{+}$ in the column was decontaminated for 0.4 day, the 72% of a total of Cs$^{+}$ in the column was decontaminated for 0.8 day, the 83% of a total of Cs$^{+}$ in the column was decontaminated for 1.2 days, the 89% of a total of Cs$^{+}$ in the column was decontaminated for 1.6 days, and the 93% of a total of Cs$^{+}$ in the column was decontaminated for 2.1 day Meanwhile, the predicted values of residual concentration by the developed model were quite similar to those obtained from experiments.m experiments.

• 한국ITS학회:학술대회논문집
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• v.2007 no.10
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• pp.35-41
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• 2007

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1993.10a
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• pp.24-31
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• 1993

In the design of column, computation of effective length factor for calculation of allowable compressive stress is inevitable. In this study. computer code which automatically generates effective length factor in the finite element analysis is developed. The program is developed to be used for orthogonal and nonorthogonal frame structure. Some i1lustrative examples verify that the computation results we correct for various cases.

• Toxicological Research
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• v.5 no.2
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• pp.97-104
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• 1989

A new exposure system was developed to generate p-dinitrobenzene (p-DNB) containing atmosphere. A glass column was filled with small glass beads coated with the chemical. The p-DNB containing medium was heated to a temperature beyond the boiling point of p-DNB. A stream of air flow was forced to pass through the column and let it mixed with fresh air before introducing into an inhalation chamber. The concentration of p-DNB in the chamber air was measured by direct assaying the air directly and by sampling the chemical using a microfilter installed in the chamber.

• The KIPS Transactions:PartD
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• v.10D no.6
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• pp.907-916
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• 2003

Database benchmarks require efficient of large-scale data. This presents the system architecture, control flows, and characteristics of the data generator we have developed. The data generator features generation of large-scale data, column-by-column data generation, a number of data distributions and verification, and real data generation. An extensive conparison with other data generators in terms of function is also presented. Finally, empirical performance experiments between RAID systems and non-RAID one have been conducted to alleviate I/O bottleneck. The test results can serve as guidelines to help confifure system architecture.

• Journal of Korean Society of Transportation
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• v.26 no.2
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• pp.89-100
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• 2008

In an urban network controlled by traffic signals, there is an interaction between the signal timing and the routes chosen by individual road users. This study develops a bi level programming model for traffic signal optimization in networks with path based traffic assignment. In the bi level programming model, genetic algorithm approach has been proposed to solve upper level problem for a signalized road network. Path based traffic assignment using column generation technique which is proposed by M.H. Xu, is applied at the lower-level. Genetic Algorithm provieds a feasible set of signal timings within specified lower and upper bounds signal timing variables and feeds into lower level problem. The performance of this model is investigated in numerical experiment in a sample network. In result, optimal signal settings and user equilibrium flows are made.

• Journal of the Korean Chemical Society
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• v.54 no.6
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• pp.696-700
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• 2010

Yeast is immobilized upon $100{\mu}m$ CPG(controlled pore glass bead) to separate $Sb^{3+}$ and $Sb^{5+}$. Continuous hydride generation is performed after the bio-column. The optimum conditions are 0.8 M nitric acid as an eluent with the flow rate of 1.0 mL $min^{-1}$ and the optimum conditions for the generation of hydride are 2 M HCl, 3% (w/v) $NaBH_4$ with the flow rate of 0.83 mL $min^{-1}$, Ar carrier gas flow rate of 50 mL $min^{-1}$. Two species are separated at 112 and 354 seconds each. The sensitivity is enhanced by 10 times for $200{\mu}L$ of sample and the detection limits are 3.0 ppb and 7.0 ppb for $Sb^{3+}$ and $Sb^{5+}$, respectively. When compared with the standard samples, this method showed accurate results.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.1
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• pp.57-65
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• 2017

In a column experiment with low rank coal, rice straw was additionally supplied to induce methane gas generation by microorganisms in the state of supplying microorganisms and nutrients, and long-term biogas production characteristics were observed. When the weight ratio of the rice straw to coal was 0.04 or less, there was no significant gas generation. At 0.08, the biogas was generated for about 90 days. However, the methane gas generation was only 5% compared with the vial test result at optimum condition. Therefore, in order to produce biogas in the coal deposit in situ, a reactor that operates at COD concentration of 2000 mg/L or more at a ratio of 1:3 or more of rice straw to coal should be installed on the ground or under the ground. Liquid from the column filled with coal and rice straw and a liquid from vial containing rice straw were analyzed by microbial community analysis using pyrosequencing method, and compared the dominant microbial species among the two samples. In terms of the uniformity and diversity of the bacteria, the coal-filled column showed various species distribution, which has shown to be a disadvantageous microbial distribution to methane production.