• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.557-562
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• 2004

A surface-piercing barrier model is presented for understanding morphological development in the sheltered region and investigating the main factors causing the severe accumulation. Surface-piercing structures like vertical barriers, surface docks and floating breakwaters are recently favored from the point of view of a marine scenario since they do not in general partition the natural sea. The numerical solutions are compared with experimental data on wave profiles and morphological change rates within a rectangular harbor of a constant depth protected by surface-piercing thin breakwaters as a simplified problem. Our numerical study involves several modules: 1) wave dynamics analyzed by a plane-wave approximation, 2) suspended sediment transport combined with sediment erosion-deposition model, and 3) concurrent morphological changes. Scattering waves are solved by using a plane wave method without inclusion of evanescent modes. Evanescent modes are only considered in predicting the reflection ratio against the vertical barrier and energy losses due to vortex shedding from the lower edge of plate are taken into account. A new relationship to relate the near-bed concentration to the depth-mean concentration is presented by analyzing the vertical structure of concentration. The numerical solutions were also compared with experimental data on morphological changes within a rectangular harbor of constant water depth. Through the numerical experiments, the vortex-induced flow appears to be not ignorable in predicting the morphological changes although the immersion depth of a plate is not deep.

• Biotechnology and Bioprocess Engineering:BBE
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• v.7 no.1
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• pp.26-30
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• 2002

A droplet fractionation method was previously developed to concentrate a dilute nonfoaming protein solution. In that earlier study with invertase, it was demonstrated that droplets created by ultrasonic energy waves could be enriched up to 8 times that of the initial dilute invertase solution. In this study, a mixture of bromelain (a foaming protein) and invertase (a nonfoaming protein) is investigated as a preliminary step to determine if droplet fractionation can also be used to separate a non-foaming protein from foaming proteins. The foaming mixture containing bromelain is first removed by bubbling the binary mixture with air. After the foam is removed, the protein rich air-water interfacial layer is skimmed off (prior to droplet fractionation) so as not to interfere with the subsequent droplet production from the remaining bulk liquid, rich in non-foaming protein. Finally, sonic energy waves are then applied to this residual bulk liquid to recover droplets containing the non-foaming protein, presumed to be invertase. The primary control variable used in this droplet fractionation process is the pH, which ranged for separate experiments between 2 and 9. It was observed that the maximum overall protein partition coefficients of 5 and 4 were achieved at pH 2 and 4, respectively, for the initial foaming experiment followed by the post foaming droplet fractionation experiment.

• Journal of the Korean Solar Energy Society
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• v.27 no.4
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• pp.59-65
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• 2007

This study is to propose the basic data for deciding remodeling of wornout educational facilities. In order of it, the indoor environmental standard, the actual conditions of thermal environment and sound insulation of walls were examined through field measurement in the subjected open elementary school(J school) and modernization model of elementary school(Y school) which they are located in Seoul. As the result, standard for indoor environmental factors of educational facilities which is established by Ministry of Education is not subdivided into indoor environmental performances considering usages and characteristics of classrooms for comfortable indoor environment. The vertical temperature difference in general classroom and in open classroom showed to be $11.2^{\circ}C$ and $12.1^{\circ}C$ respectively, while indoor temperature of special classroon was, on the whole, higher than that of any other classroom due to its specific heat flux of wall materials. The sound insulation performance of the masonry brick wall of classroom satisfied the minimum standard of AIJ, Architectural Institute of Japan, in the open elementary school and the modernization model of elementary school. That is to say, the movable partition wall between the classroom and the corridor disturbed students in their class in the open school.

• Journal of Soil and Groundwater Environment
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• v.27 no.6
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• pp.11-21
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• 2022

Sorption of phenanthrene (PHE) and pyrene (PYR) in several sorbents, i.e., natural soil, BionSoil^®, Pahokee peat, vermicompost and Devonian Ohio Shale and a surfactant (hexadecyltrimethyl ammonium chloride)-modified montmorillonite (HDTMA-M) were investigated. Pyrene exhibited higher sorption tendency than phenanthrene, as predicted by its higher octanol to water partition coefficient (K_ow). Several sorption models: linear, Freundlich, solubility-normalized Freundlich model, and Polanyi-Manes model (PMM) were used to analyze sorption isotherms. Linear isotherms were observed for natural soil, BionSoil^®, Pahokee peat, vermicompost, while nonlinear Freundlich isotherms fitted for Ohio shale and HDTMA-M. The relationship between sorption model parameters, organic carbon content (f_oc), and elemental C/N ratio was studied. In the binary competitive sorption of phenanthrene and pyrene in natural soil, competition between the solutes caused reduction in the sorption of each solute compared with that in the single-solute system. The ideal adsorbed solution theory (IAST) coupled with the single-solute Freundlich model was not successful in describing the binary competitive sorption equilibria. This was due to the inherent nature of linear sorption of phenanthrene and pyrene in natural soil. The result indicates that the applicability of IAST for the prediction of binary competitive sorption is limited when the sorption isotherms are inherently linear.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.5B no.2
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• pp.103-110
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• 2005

Broken rotor bars in induction motors can be detected by monitoring any abnormality of the spectrum amplitudes at certain frequencies in the motor current spectrum. Broken rotor bar fault detection schemes should rely on multiple signatures in order to overcome or reduce the effect of any misinterpretation of the signatures that are obscured by factors such as measurement noises and different load conditions. Multiple Discriminant Analysis (MDA) and Artificial Neural Networks (ANN) provide appropriate environments to develop such fault detection schemes because of their multi-input processing capabilities. This paper describes two fault detection schemes for broken rotor bar fault detection with multiple signature processing, and demonstrates that multiple signature processing is more efficient than single signature processing.

• Tribology and Lubricants
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• v.18 no.4
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• pp.305-311
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• 2002

Three different kinds of brake discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. A braking test bench was specially designed to analyse thermo-mechanical and frictional behaviors of two types of brake with different sizes in stop and hold braking modes. Plasma spray coating technique was also used to coat the discs with ceramic powder. During the test four commercial brake pads were coupled with discs. Ceramic coated discs showed good stability in friction coefficient at high speed and high energy braking conditions. But they caused large wear loss of pad mass compared with the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. For a steel disc. it showed fluctuating friction coefficient at high speed but small wear loss of pad mass compared with ceramic coated discs.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.429-430
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• 2002

In this study, three kinds of brake: discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. Plasma spray coating technique was used to coat ceramic powder on the discs. In the test, four commercial sintered brake pads were coupled with discs. Ceramic coated discs have shown good stability in friction coefficient at high speed and high energy braking conditions. However, ceramic coated discs caused more wear loss of pad mass than the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. Steel disc showed fluctuating friction coefficient at high speed but less wear loss of pad mass than ceramic coated discs.

• Structural Engineering and Mechanics
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• v.68 no.1
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• pp.17-38
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• 2018

In this paper, we compare and assess the performance of the standard 3- and 6-node MITC shell elements (Lee and Bathe 2004) with the recently developed MITC triangular elements (Lee et al. 2014, Jeon et al. 2014, Jun et al. 2018) which were based on the partitions of unity approximation, bubble node, or both. The convergence behavior of the shell elements are measured in well-known benchmark tests; four plane stress tests (mesh distortion test, cantilever beam, Cook's skew beam, and MacNeal beam), two plate tests (Morley's skew plate and circular plate), and six shell tests (curved beam, twisted beam, pinched cylinder, hemispherical shells with or without hole, and Scordelis-Lo roof). To precisely compare and evaluate the solution accuracy of the shell elements, different triangular mesh patterns and distorted element mesh are adopted in the benchmark problems. All shell finite elements considered pass the basic tests; namely, the isotropy, the patch, and the zero energy mode tests.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.97-107
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• 1998

Three different kinds of brake discs including two coated brake discs and one steel disc were tested under the same experimental conditions on a reduced scale braking test bench. Braking test bench was specially designed to analyse thermo-mechanical and frictional behaviors of two sizes of brake discs in stop and hold braking modes. And Plasma spray coating technique was used to coat ceramic powder on the discs. In the test four commercial brake pads were coupled with discs. Ceramic coated discs had shown good stability in friction coefficient at high speed and high energy braking conditions. But they caused large pad mass wear loss compared with the steel disc. It was shown that thermal barrier effect in ceramic coated discs adjusted the thermal partition between pad and disc. For a steel disc, it had shown fluctuating friction coefficient at high speed but a fittie pad mass wear loss compared with ceramic coated discs.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.26-29
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• 2001

Sorption/desorption Study was conducted to determine desorption-resistance hydrophobic organic compounds in natural soils with low organic carbon content. Sorption/desorption characteristics of chlorobenzene and phenanthrene for both PPI (Petro Processors, Inc. Superfund site) and BM (Bayou Manchac), soils were investigated. Desorption was biphasic including reversible and desorption-resistant compartments. The biphasic sorption parameters indicated the presence of appreciable size of desorption-resistant phase in these soils. A finite maximum capacity of desorption-resistant fraction (equation omitted) was observed after several desorption steps. The apparent organic carbon based Partition coefficient, K(equation omitted) was 10$^{4.92{\pm}0.27}$ for PPI soil and 10$^{4.92{\pm}0.27}$ for BM soil, respectively. The difference in K(equation omitted) was attributed to different characteristics in soil organic matter. The results suggest that desorption-resistance should be considered in remediation and risk assessments in natural soils and sediments.