• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.6
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• pp.787-796
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• 1996

The biodegradation experiment, the TOD analysis and the element analysis for dispersant, Bunker-A oil and Bunker-B oil were conducted to study the biodegradation characteristics of a mixture of Bunker-A oil with dispersant and a mixture of Bunker-B oil with dispersant in the seawater. The results of biodegradation experiment showed 1mg of dispersant to be equivalent to 0.26 mg of $BOD_5$ and to 0.60 mg of $BOD_{20}$ in the natural seawater. The results of TOD analysis showed each 1 mg of dispersant, Bunker-A oil and Bunker-B oil to be equivalent to 2.37 mg, 2.94 mg and 2.74 mg of TOD, respectively. The results of element analysis showed carbon, hydrogen, nitrogen and phosphorus contents of dispersant to be $82.1\%,\;13.8\%,\;1.8\%\;and\;2.2\%$, respectively. Carbon and hydrogen contents of Bunker-A oil were found to be $73.3\%\;and\;13.5\%$, respectively, and carbon, hydrogen and nitrogen contents of Bunker-B oil to be $80.4\%,\;12.3\%\;and\;0.7\%$, respectively. Accordingly, the detection of nitrogen and phosphorus in dispersant shows that dispersants should be used with caution in coastal waters, with relation to eutrophication. The biodegradability of dispersant expressed as the ratio of $BOD_5/TOD$ was found to be $11.0\%$. As the mix ratios of dispersant to Bunker-A oil (3 mg/l) and a mixture of Bunker-B oil (3mg/l) were changed from 1 : 10 to 5 : 10, the biodegradabilities of a mixture of Bunker-A oil with dispersant and Bunker-B oil with dispersant increased from $2.1\%\;to\;7.2\%$ and from $1.0\%\;to\;4.4\%$, respectively. Accordingly, the dispersant belongs to the organic matter group of middle-biodegradability while mixtures in the mix ratio range of $1:10\~5:10$ belong to the organic matter group of low-biodegradability. The deoxygenation rate constant $(K_1)$ and ultimate biochemical oxygen demand $(L_0)$ obtained from the biodegradation experiment and Thomas slope method were found to be 0.125/day and 2.487 mg/l for dispersant (4 mg/l), respectively. $K_1\;and\;L_0$, were found to be $0.079\~0.131/day$ and $0.318\~2.052\;mg/l$ for a mixture of Bunker-A oil with dispersant and to be $0.106\~0.371/day$ and $0.262\~1.106\;mg/l$ for a mixture of Bunker-B oil with dispersant, respectively, having $1:10\~5:10$ mix ratios of dispersant to Bunker-A oil and Bunker-B oil. The ultimate biochemical oxygen demands of the mixtures increased as the mix ratio of dispersant to Bunker-A, B oils changed from 1 : 10 to 5 : 10. This suggests that the more dispersants are applied to the sea for the cleanup of Bunker-A oil or Bunker-B oil, the more decreases the dissolved oxygen level in the seawater.

• Journal of Soil and Groundwater Environment
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• v.21 no.1
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• pp.28-39
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• 2016

Struvite (MgNH₄PO₄ ⋅ 6H₂O) and hydroxyapatite (HAP, Ca₁₀(PO₄)₆(OH)₂) precipitation in urine-separating toilets (NoMix toilets) causes severe maintenance problems and also reduce the phosphate and calcium content. Application of urine separating technique and extraction of by-products from human urine is a cost effective technique in waste water treatment. In this study, we extract urine calcite from human urine by batch scale method, using urease producing microbes to trigger the precipitation and calcite formation process. Extracted urine calcite (calcining at 800℃) is a potential adsorbent for removal of heavy metal(loid)s like (Cd²⁺, Cu²⁺, Ni²⁺, Pb²⁺, Zn²⁺ and As³⁺) along with additional leaching analysis of total nitrogen (T-N), phosphate (T-P) and chemical oxygen demand (COD). The transformations of calcite during synthesis were confirm by characterization using XRD, SEM-EDAX and FT-IR techniques. In additional, the phosphate leaching potential and adsorbate (nitrate) efficiency in aqueous solution was investigated using the calcinedurine calcite. The results indicate that the calcite was effectively remove heavy metal(loid)s lead up to 96.8%. In addition, the adsorption capacity (q_e) of calcite was calculated and it was found to be 203.64 Pb, 110.96 Cd, 96.02 Zn, 104.2 As, 149.54 Cu and 162.68 Ni mg/g, respectively. Hence, we suggest that the calcite obtain from the human urine will be a suitable absorbent for heavy metal(loid)s removal from aqueous solution.

• Information Systems Review
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• v.24 no.2
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• pp.1-20
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• 2022

Researchers are making contradictory claims through the concept of superstars and long tails about how the development of IT technology affects demand distribution. Unlike previous studies that focused on changes in demand from a macro point of view, this study explored whether the relationship between a company's marketing activities and consumer response differs depending on the product location (i.e., superstar vs. long tail) from a micro point of view. Based on the marketing mix framework, hypotheses were developed based on the relevant literature. In the case of empirical analysis, 2,835 daily data from 63 Korean films were tested using the quantile regression method. As a result of the analysis, it was found that the influence of marketing mix factors on sales varies depending on the location of the product. Specifically, the appeal breadth of the film and the effect of owned media are enhanced in superstar products, and the effect of acquisition media in long-tail products is enhanced and the negative effects of competition are mitigated. Unlike previous studies that focused on macroscopic changes in demand distribution, this study suggested marketing activities suitable for practitioners through microscopic analysis.

• Research in Mathematical Education
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• v.18 no.4
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• pp.257-272
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• 2014

This paper examines and presents descriptions of 12 prospective primary teachers' views on the nature of mathematics in USA. All the participants were elementary teacher candidates enrolled in the same mathematics method courses. Interview data show that the prospective primary teachers possess two kinds of views on the nature of mathematics: primarily traditional and even mix of traditional and nontraditional beliefs in terms of Raymond's (1997) belief criteria. Implications for teacher education were discussed at the end of the paper.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.77-82
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• 1994

The maturity concept proposes that concrete of the same mix at the same maturity has the same strength, whatever combination of temperature and time makes up that maturity. Maturity is the integral of time and temperature of concrete above a datum temperature. Tests are conducted in order to determine a datum temperature and to measure compressive strengths and maturity of test specimens. This study also proposes some appropriate functions to represent the relationship between maturity and strength development.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.111-114
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• 2001

This study is a fundamental research for recycling waste vinyl in asphalt concrete mixture for roadway pavement. The mixing method and proper content of waste polyethylene(PE) film were determined through preliminary mix design. This study used 2-type aggregate gradations and two-type waste PE films. The mixtures were applied for a test pavement on a rural road. Quality evaluation of the asphalt concrete confirmed that waste vinyl asphalt concrete was applicable to road pavement.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.639-642
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• 2003

In this paper, fatigue behavior of concrete slab tracks under railway loads by experimental method is discussed. The addition of steel fibers to concrete mix has been receiving more attention as a way of improving the crack behavior of concrete beams an slabs tacks. This study two objectives: 1) to observe the fatigue behavior of fiber reinforced concrete slab in labor, and 2) to present crack propagation and deflection of fiber reinforced concrete slab track under railway loads in the Waghauser test line. Nine beams, two slabs and one test track were experimentally tested.

• Proceedings of the Korea Concrete Institute Conference
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• 1993.10a
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• pp.51-56
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• 1993

This is a part a study on the development of High-Performance Concrete ; about experimental results from several test methods to estimate workability in fresh concrete and influences of concrete mix design that affects properties of super-flowing concrete. Super-flowing concrete can be filled in a formwork without any vibration because of its excellent workability of passing narrow space and filling complicated shaped mold, new test methods should be used to estimate the workability and rhelogy in super-flowing concrete instead of slump test method in conventional concrete.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10a
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• pp.100-101
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• 2007

• IE interfaces
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• v.14 no.1
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• pp.30-38
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• 2001

Logistics network management has become one of the most important sources of competitive advantage regarding logistics cost and customer service in numerous business segments. Logistics network simulation is a powerful analysis method for designing and planning the logistics network optimally in an integrated way. This paper introduces a logistics network simulator, LONSIM, developed by author. LONSIM deploys a mix of simulation and optimization functions to model and analysis logistics network issues such as facility location, inventory policy, manufacturing policy, transportation mode, warehouse assignment, supplier assignment, order processing priority rule, and vehicle routes. LONSIM is built with AweSim 2.1 and Visual Basic 6.0, and executed in windows environment.