• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.635-644
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• 1994

A mathematical model was developed to predict the concentrations of various nutrients in supernatants during aerobic digestion which is suitable to be employed in small wastewater treatment plants with such advantages as low capital cost and stable process. Significant reactions were determined with observing the behavior of nitrgen and phosphorus, and the model equations were built up in the form of simultaneous differential equations considering Mass Balance. Laboratory batch experiments were carried out at $20^{\circ}C$ and pH $7.5{\pm}0.5$ on the aerobic digestion of waste activated sludge at different solid levels. Nonlinear regression analysis was performed to estimate various reaction rate constants. The developed model can predict the behavior of Biomass N, dissolved organic N, $NH_4{^-}$-N, $NO_x{^-}$-N, and Biomass P, dissolved organic P, $PO_4{^-}$-P in aerobic digestion process. In this study, the results of simulation showed that dissolved nutrients had more effects on supernatants than nutrients in biomass, and phosphorus was more effective on supernatants than nitrogen.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.711-711
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• 2009

Global warming has been widely recognized as a serious problem threatening the future of human beings. It is caused by the buildup in the atmosphere of greenhouse gases, such as carbon dioxide, methane, hydrofluorocarbons (HFCs), and sulfur hexafluoride (SF6). Particularly, SF6 has extremely high global warming potential compare to those of other global warming gases. One option for mitigating this greenhouse gas is the development of an effective process for capturing and separating these gases from anthropogenic sources. In general, gas hydrates can be formed under high pressure and low temperature. However, SF6 gas is known to form hydrate under relatively milder conditions. Therefore, technological and economical effects could be expected for the separation of SF6 gas from waste gas mixtures. In this study, we carried out morphological study for the SF6 hydrate crystals to understand its formation and growth mechanisms. The observations were made in high-pressure optical cell charged with liquid water and SF6 gas at constant pressure and temperature. Initially SF6 hydrate formed at the surface between gas and liquid regions, and then subsequent dendrite crystals grew at the wall above the gas/water interface. The visual observations of crystal nucleation, migration, growth and interference were reported. The detailed growth characteristics of SF6 hydrate crystals were discussed in this study.

• Magazine of the Korean Society of Agricultural Engineers
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• v.39 no.4
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• pp.98-105
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• 1997

Compacted clay materials are often used to form barriers for waste disposal by means of landfill. The performance of clay barrier depends on its permeability characteristics under the site environments. The study discusses permeability characteristics of 4 types of permeants through a compacted clayey soil. Permeabilities are measured using the modified rigid-wall permeater and with water, PEG, Ethanol, and TCE, ranging 80 to 3.4 of dielectric constants. Results of the study are as follows : 1) Absolute permeabilities of Ethanol and TCE that their dielectric constants are lower than that of water are $K=1.0{\times} 10^{-12} cm^2$, and $5.8{\times} 10^{-12} cm^2$, respectively, that is, 1.67, and 9.67 times of permeability of water, respectively. Absolute permeability and dielectric constant of water are $K=6{\times} 10^{-13} cm^2$, and 80, respectively. 2) Changes in absolute permeability of Ethanol and TCE converge to a constant after 3.5 pore volume of permeant flows through the clay sample. This can be explained that diffuse double layer of clay is no longer reacted with permeants and contracted their pores. However there is no change in absolute permeability when water is used as a per-meant. 3) It is found that absolute permeability in reversely proportional to the value of dielectric constant of the permeants. Change in absolute permeability of the permeants with 40 or over of dielectric constant is not significant. However change in absolute permeability of the permeant with 30 or lower dielectric constant is abruptly increased. 4) A lower absolute permeability of PEG is found because of its high viscosity.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.107-113
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• 2012

Pollutants in aquaculture system effluent mostly originated from solid wastes including uneaten feed and excreta of cultured species. In this research, DAF(Dissolved Air Flotation) unit is suggested as an integrated solid control unit especially as a form of IIBG(Inline Injection Bubble Generation) process in aquaculture system. Solid removal performance of DAF unit was examined under various operation and salinity conditions with turbidity and suspended solid. Solid waste removal efficiencies were found to be affected by operation conditions including saturator pressure, recycle ratio, coagulant concentration. Solid removal efficiency was higher under higher saturator pressure and recycle ratio under which condition larger number of bubbles is generated. Coagulant is thought to have important role in creating bubble-particle aggregate by showing better removal efficiency with higher concentration. However higher saline water showed less effectiveness in removing solids by DAF(IIBG). Application of DAF(IIBG) process also showed additional effect in phosphate removal and DO(Dissolved Oxygen) supply. Phosphate existed in polluted water was removed up to 46% after treatment, which is thought to attribute to aluminium phosphate precipitation. And DO concentration was found to increase over 50% of initial saturation concentration after the injection of micro-bubbles. Through experiments on solid removal from aquaculture effluent, DAF(IIBG) process is estimated to be effective solid control method. This property can help aquaculture system being installed and operated simply and effectively.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.573-576
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• 2008

Recently, it is the well-known that there are some kinds of problem the waste concrete generated while repairing, reinforcing and dismantling of structures in the domestic and overseas. In this paper, various tests were performed about the use of the recycled concrete fine aggregate for the materials of high quality and structural concrete. And also, in order to improve structural performance of the concrete structure the steel frame was under overcrowded arrangement of steel bar. Consequently, it was be necessary the Self-Consolidating Concrete(SCC) that can fill the concrete into the work-form corner which has become overcrowded arrangement of steel bar without any other vibration. The purpose of this study is related to the properties of Self-Consolidating Concrete(SCC) according to mixing ratio of recycled concrete fine aggregate.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.10
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• pp.2316-2322
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• 2012

The present study investigates a standardized framework for support system of ship design engineering. The purpose of this research is to improve the efficiency of information gathering and its use in tasks of the ship design engineering support system. Due to their variety and complexity, the existing engineering methods tend to waste time in searching for the standardized method and knowledge or to cause errors on tasks. Generally, these kinds of system have serious problems. The most serious one among them is that the existing system consists of both useful and useless data. This finally leads engineers to a failure in finding out useful information from the system. We have designed a standardized framework, which enables users to properly recompose the menu form depending on the task process, simplifies the methods at several process levels, and provides a more intuitive method in user interface environment in order to resolve the existing problems, minimize the system-operating costs, and improve the efficiency of engineering tasks.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.2
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• pp.85-90
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• 2018

For the recovering rare earths in the spent nickel-metal hydride batteries, 10 M NaOH is added to the solution leached with sulfuric acid. The rare earth powders were precipitated at rate of 98 % at the condition of pH 2.0 or less. The recovered rare earth complex precipitate increased the leaching rate to nitric acid by heat treatment at $800^{\circ}C$ for 4 hours. Subsequently secondary precipitation was performed by adding oxalic acid to the solution in which the rare earth complex precipitate was dissolved. The re-precipitated rare earth powders were converted into oxide form through heat treatment at $800^{\circ}C$ for 4 hours with purity of 99.5 %.

• Journal of the Korea Fashion and Costume Design Association
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• v.6 no.3
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• pp.153-167
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• 2004

Korea had suffered the colony of Japanese imperialism and the Korean War from the invasion of the external circumstances. Such special situation made new influences on the clothing habits. The types of Korean women clothing could escape from the traditional style that had been maintained for thousands of years. The foreign clothes for Korean women had undergone various changes from the Liberation in 1945. The jackets that had been introduced to Korea at the Enlightenment period had become popular outfits for men. The jackets made big influences on the changes such as the social advances for women from the times background of the Liberation. The jackets possess very important meaning for the changes in the diffusion of feminism and fashion. Therefore, this research tries to investigate the forms, silhouettes, changes and structures of the jackets such as the locations of the collar, the sleeve, and the waste line. The process of the changes in the style of women jackets is also analyzed from the silhouette and the structure method. The development and changes will be understood of Korean women's jackets. The Korean women's jackets should also be examined further with the history of foreign clothing from now on. The fashion to be introduced from important society cultural phenomena and the Western Europe has been reflected into the changes in the style of Korean female jackets. Also, dramatic changes in the style of clothing indicate that the society had experienced a great deal of changes. It is verified that foreign clothes have been interacted with the stream of times worldwide. After the Liberation, the female jackets become a uniform style which just followed the Western European style. However, a season trend has been announced from the SFAA since 1990. Since then trendy jackets have been detailed more with this chance.

• Journal of the Korean Society of Costume
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• v.60 no.6
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• pp.1-10
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• 2010

The cultures and traditions of Asia has the roots so deep and it is the origin of inspiration. Therefore, it is easy to find a different inspiration when designing, expecially for Western designers who are seeking European tradition and its comparison. The most distinctive feature of the Asian look is non-structural and has no clear form close to the structure of the body or mathematical ratio, but is steric with 2-Dimensional planed textiles, and has a flexible, non-structural formative characteristic related to the movable body. This is base on the vision of the universe that regards the parts as the whole. From this research, generally studying about the Asian look and its non-structural formative characteristics. The study looked closely into the aesthetic value of non-structural formative characteristics formation, with basis on the large dress regulation system of the western reasoning and rationalism and mechanism. At first, my study pointed on the dressing functionalism or Neo-classism considering emotions, Anti-Western aspect observing surrealism dressing and expressionism dressing. Second, with men and women showing similar outer shape without the equivalent element such from wearing a corset, the sexism is abolished. Finally, the designers’ inner intention of art is being delivered, from the aspect that the expression of art, size and no waste of fabric shows effort of communicating with the world, giving value to the possibility of continuance.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.237-240
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• 2002

Knowing the dose distribution in a tissue is as important as being able to measure exposure or absorbed dose in radiotherapy. Since the Dry Imager spread, the wet type automatic processor is no longer used. Furthermore, the waste fluid after film development process brings about a serious problem for prevention of pollution. Therefore, we have developed a measurement method for the dose distribution (CR dosimetry) in the phantom based on the imaging plate (IP) of the computed radiography (CR). The IP was applied for the dose measurement as a dosimeter instead of the film used for film dosimetry. The data from the irradiated IP were processed by a personal computer with 10 bits and were depicted as absorbed dose distributions in the phantom. The image of the dose distribution was obtained from the CR system using the DICOM form. The CR dosimetry is an application of CR system currently employed in medical examinations to dosimetry in radiotherapy. A dose distribution can be easily shown by the Dose Distribution Depiction System we developed this time. Moreover, the measurement method is simpler and a result is obtained more quickly compared with film dosimetry.