• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.5
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• pp.610-620
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• 1999

Recently, numerous modifications of low Reynolds number $k-{\epsilon}$ model have boon carried out with the aid of DNS data. However, the previous models made in this way are too intricate to be used practically. To overcome this shortcoming, a new low Reynolds number $k-{\epsilon}$ model has boon developed by considering the distribution of turbulent properties near the wall. This study proposes the revised a turbulence model for prediction of turbulent flow with adverse pressure gradient and separation. Nondimensional distance $y^+$ in damping functions is changed to $y^*$ and some terms modeled for one dimensional flow in $\epsilon$ equations are expanded into two or three dimensional form. Predicted results by the revised model show an acceptable agreement with DNS data and experimental results. However, for a turbulent flow with severe adverse pressure gradient, an additive term reflecting an adverse pressure gradient effect will have to be considered.

• Journal of Power Electronics
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• v.17 no.5
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• pp.1288-1297
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• 2017

The estimation of the remaining useful life (RUL) of lithium-ion (Li-ion) batteries is important for intelligent battery management system (BMS). Data mining technology is becoming increasingly mature, and the RUL estimation of Li-ion batteries based on data-driven prognostics is more accurate with the arrival of the era of big data. However, the support vector machine (SVM), which is applied to predict the RUL of Li-ion batteries, uses the traditional single-radial basis kernel function. This type of classifier has weak generalization ability, and it easily shows the problem of data migration, which results in inaccurate prediction of the RUL of Li-ion batteries. In this study, a novel multi-kernel SVM (MSVM) based on polynomial kernel and radial basis kernel function is proposed. Moreover, the particle swarm optimization algorithm is used to search the kernel parameters, penalty factor, and weight coefficient of the MSVM model. Finally, this paper utilizes the NASA battery dataset to form the observed data sequence for regression prediction. Results show that the improved algorithm not only has better prediction accuracy and stronger generalization ability but also decreases training time and computational complexity.

• Journal of Surface Science and Engineering
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• v.42 no.1
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• pp.53-57
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• 2009

Recovery of heavy-metallic component from a waste solution of factory was undertaken by the solar cell electricity. The solution was obtained from an electrolytic etching process of 316L stainless steel. The electrolysis of the solution for recovery of heavy metallic components was made with platinum plated titanium mesh anode and copper plate cathode. Analysis for the solution and electro-winned materials were made by EDS, XRD and SEM. Iron, chromium, and sulfur components were recovered on the cathode from the solution. Result of EDS analysis for the electro-winned materials revealed that some metal oxide were contained in the recovered material. The recovered materials were expected to have metallic form only by the electrolysis, but metal compounds were contained because of weak solar cell power. Nickel and manganese component in the solution doesn't recovered by this electrolysis process, but they made a sludge with phosphoric acid in the solution.

• Journal of Conservation Science
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• v.4 no.1 s.4
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• pp.11-42
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• 1995

Stone-monuments, distributed in this area, have been investigated and studied on the characteristics and the rock phases in the geological and conservational points of view. Most of them may have been built from the end of the Shilla Kingdom to the Koryeo Kingdom, which are based on the typical characteristics of the form. The used rocks in these monuments are mainly biotite granite of the Jurassic age which is widely distributed around the area. Black slate and marbles are also used in some monuments, which may be obtained from other areas. The biotite granite of massive and coarse texture contains often inclusions of biotite aggregates or fragments of dioritic rock phase. However, the biotite granite in the area may be very weak to the chemical weathering so that irregular rock surface shows generally $2\~3mm$ relief. The irregular relief is mainly due to different relative degree on the chemical weathering according to the kind of minerals especially quartz, feldspar and biotite. The chemical weathering is also influenced by organisms. For conservation, they must be scientifically considered based on the characteristics, kind of the rock phase, factors on the weathering process, situation in situ or being transported, and protection.

• Fisheries and Aquatic Sciences
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• v.14 no.4
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• pp.295-301
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• 2011

We investigated the genetic structure of Korean and Japanese ayu Plecoglossus altivelis populations by examining 669 individuals from 14 populations using three microsatellite loci. Genetic variation did not differ significantly among the populations examined in terms of allelic number and heterozygosity. Korean populations were genetically close to each other, implying that persistent gene flow has occurred in these populations. This suggests that eastern populations in Korea form a single large population and all of the Korean populations are distinct from the Japanese populations. Pairwise population $F_{ST}$ estimates, principal component analyses, and a neighbor-joining tree showed that genetic separation between the southern and pooled eastern coast populations was probably influenced by restricted gene flow. Hierarchical analysis of molecular variance (AMOVA) revealed a weak but significant genetic structure among three ayu groups (eastern and southern coasts of Korea and the Japan coast), and no genetic variation within groups. The estimated genetic population structure and potential applications of microsatellite markers may aid in the proper management of ayu populations.

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1527-1532
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• 2007

Lysine produced during microbial fermentation is usually recovered by an ion-exchange process, in which lysine is first converted to the cationic form (by lowering the pH to less than 2.0 with sulfuric acid) and then fed to a cationexchange column containing an exchanger that has a sulfone group with a weak counterion such as NH;. Ammonia water with a pH above 11 is then supplied to the column to displace the purified lysine from the column and allow its recovery. To enhance the adsorption capacity and for a possible reduction in chemical consumption, monovalent lysine fed at pH 4 was investigated in comparison with conventional divalent lysine fed at pH 1.5. The adsorption capacity increased by more than 70% on a mass basis using pH 4 feeding compared with pH 1.5 feeding. Lysine adsorbed at pH 4 started to elute earlier than that adsorbed at pH 1.5 when ammonia water was used as the eluant solution, and the extent of early elution became more notable at lower concentrations of ammonia. Moreover, the elution of monovalent lysine fed at pH 4 displayed a stiffer front boundary and higher peak concentration. However, when the ammonium concentration was greater than 2.0 N, complete saturation of the bed was delayed during adsorption and the percent recovery yield from elution was lowered., both drawbacks that were considered inevitable features originating from the increased adsorption of monovalent lysine.

• Korea-Australia Rheology Journal
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• v.20 no.3
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• pp.165-173
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• 2008

Multiple particle tracking microrheology is used to characterize the viscoelastic properties of biomaterial and synthetic polymer gels near the liquid-solid transition. Probe particles are dispersed in the gel precursors, and their dynamics are measured as a function of the extent of reaction during gel formation. We interpret the dynamics using the generalized Stokes-Einstein relationship (GSER), using a form of the GSER that emphasizes the relationship between the probe particle mean-squared displacement and the material creep compliance. We show that long-standing concepts in gel bulk rheology are applicable to microrheological data, including time-cure superposition to identify the gel point and critical scaling exponents, and the power-law behavior of incipient network's viscoelastic response. These experiments provide valuable insight into the rheology, structure, and kinetics of gelling materials, and are especially powerful for studying the weak incipient networks of dilute gelators, as well as scarce materials, due to the small sample size requirements and rapid data acquisition.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.124-129
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• 2011

An improved NDIF method is introduced to efficiently extract eigenvalues of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, membranes, and plates, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods (FEM and BEM). However, the NDIF method has the weak point that the system matrix of the NDIF method depends on the frequency parameter and, as a result, a final system equation doesn't take the form of an algebra eigenvalue problem. The system matrix of the improved NDIF method developed in the paper is independent of the frequency parameter and eigenvalues can be efficiently obtained by solving a typical algebraic eigenvalue problem. Finally, the validity and accuracy of the proposed method is verified in two case studies, which indicate that eigenvalues and mode shapes obtained by the proposed method are very accurate compared to the exact method, the NDIF method or FEM(ANSYS).

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.960-966
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• 2011

An improved NDIF method is introduced to efficiently extract eigenvalues and eigenmodes of two-dimensional, arbitrarily shaped acoustic cavities. The NDIF method, which was developed by the authors for the eigen-mode analysis of arbitrarily shaped acoustic cavities, membranes, and plates, has the feature that it yields highly accurate eigenvalues compared with other analytical methods or numerical methods(FEM and BEM). However, the NDIF method has the weak point that the system matrix of the NDIF method depends on the frequency parameter and, as a result, a final system equation doesn's take the form of an algebra eigenvalue problem. The system matrix of the improved NDIF method developed in the paper is independent of the frequency parameter and eigenvalues and mode shapes can be efficiently obtained by solving a typical algebraic eigenvalue problem. Finally, the validity and accuracy of the proposed method is verified in two case studies, which indicate that eigenvalues and mode shapes obtained by the proposed method are very accurate compared to the exact method, the NDIF method or FEM(ANSYS).

• Journal of the Korean Regional Science Association
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• v.10 no.1
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• pp.39-52
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• 1994

This paper primarily aims to analyze the growth rate differentials of the economic activities in chung-Nam area. The research has been undertaken to find out the potentials of the economic activities and economic bases in the area. To analyze the economic potentials of the industries, the study employed the economic Growth Rate Differential Analysis by Henderson which is revised form of Shift-Share Analysis Methods. The research employed the employment data according to the standardized two-digit-classification-system during the period of 10 years from 1981 through 1991. The Growth Rate Differential Analysis calculates Total Growth Differentials which are dicomposed into two parts: Weight Part and Rate Part. Total Growth Differential can be calculated as the difference between national growth rate and regional growth rate by industry. The foundings are as follows: First, the economic bases of Chung-Nam area were found to be very weak, largely depending on primary industries such as agriculture and fisheries. Second, there was a great decline in urban industries in Tae Joeon, Cheon An and other cities over period of 1971-1981. It is strongly recommended that the planned items and products of each industrial complex must be reorgnized in a fashion to match those with high competitive power found in this research.