• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.5
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• pp.698-707
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• 1998

A simplified model for predicting microsegregation during columnar-dendritic solidification of binary alloys is developed, in which back diffusion, dendrite arm coarsening and dendrite tip undercooling are simultaneously incorporated. The inclusion of tip undercooling is accomplished by modifying the initial conditions of the existing solute diffusion model, in such forms that tip undercooling depresses the beginning of solidification below the liquidus temperature, and that the secondary arm spacing evolves in accordance with the minimum undercooling theory. Sample calculations for the well-known benchmark system show that the present predictions not only consist with the extablished limiting cases, but also agree favorably with the available experimental data within a reasonable tolerance. In particular, a typical decreasing trend in the eutectic fraction at high cooling rates is successfully resolved. Comparison of the individual and combined effects of characteristic parameters in reference with the limiting cases reveals the interactions among parameters. Every parameter plays the role of reducing the eutectic fraction, and the degree of influence depends primarily on the cooling rate. Coarsening enhances the effect of tip undercooling, while suppressing that of back diffusion. A vigorous back diffusion seems to restrain the apperance of the undercooling effect. Overall, each contribution of the three parameters to microsegregation is estimated to be of the same order, which suffices to justify the present study.

• Journal of the Korean Society of Tobacco Science
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• v.33 no.1
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• pp.21-27
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• 2011

Amadori compounds(1-deoxy-1-amino-2-ketoses) are important precursors of color, flavor and aroma produced in foods. Amadori compounds occur naturally in tobacco. The contribution of amadori compounds to smoke quality has been (of) interest because of their roles of the Maillard reaction in the leaf chemistry. The amounts of these compound in tobacco are affected by the processes of aging, drying and storage conditions. In this study, eight compounds were chemically synthesized because amadori compounds (have not been sold commercially these days.) were not available for obtaining commercially. The aim of this study was to develop the analytical method of amadori compounds in tobacco leaf by the liquid chromatography mass spectrometry using triple quadrupole analyzer(LC-MS/MS). This method was simple, rapid, selective and sensitive, and eight amadori compounds were simultaneously and quantitatively analyzed within 20 minutes. This method showed excellent accuracy and precision. Recovery rates of amadori compounds ranged from 86% to 102%, with relative standard deviation(RSD) ranged from 2.6% to 5.9%. This method was applied to analysis of amadori compounds contents of tobacco leaves in different varieties. Furthermore, it was expected that the method could be extended to the analysis of other amadori compounds.

• Journal of Korean Society on Water Environment
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• v.26 no.5
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• pp.781-788
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• 2010

A pilot study was performed to examine the feasibility of multiple stage of constructed wetland (CW) for nutrient removal. The system is composed of six wetland cells connected with water-ways. The hydraulic of wetland cells is designed as free water surface flow. The treatment capacity was $25m^3d^{-1}$ at HRT of about one day for each cell. The magnitude of nutrient removal was related with the length of wetlands and plant density. Total N and P removal rates were 1353 and $246mg\;m^{-2}d^{-1}$ respectively. The pilot-scale reactor was model as continuous flow system containing contribution of CSTR and PFR typed-reactors. The $k-C^*$ model equation was applied to predict N and P reduction. The result indicated the equation was well guided to estimate reduction of $NO_3-N$ and $PO_4-P$.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.207-213
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• 1999

Thirty-eight glutinous rice varieties were classified into nine groups on the scatter diagram by the upper two principal components (56% contribution to the total information) based on eleven physicochemical characteristics including the viscograms and physical properties of cooked rice. The first principal component was the factor mainly associated with the viscogram characteristics of rice flour emulsion and the second was the factor chiefly related to the physical properties of cooked rice and water absorbability of rice grain. Indica glutinous rices were clearly distinguished from japonica ones by the first principal component score. Javanica glutinous rices were widely distributed on the intermediate zone between indica and japonica or on several japonica rice groups. Significant positive or negative correlations were found among water absorption rates of rice grain, physical properties of cooked rice, and viscogram characteristics of rice flour. Especially in japonica glutinous rices, the breakdown and setback viscosities of rice flour were closely associated with the alkali digestion value of milled rice and the stickiness of cooked rice. The frequency ratio of short glucose chains (A-chain) to intermediate glucose chains (B-chain), the ratio of B- chains to long glucose chains (C-chain) and the relative frequency of A- or B-chain fractions representing the amylopection structure of rice starch was closely associated with the breakdown and setback viscosities of rice flour.

• Asian Journal of Atmospheric Environment
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• v.9 no.1
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• pp.39-47
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• 2015

The emissions of ozone precursors, NOx and VOCs from a biogenic source and port-related sources (ship, shipping container truck, and cargo handling equipment) were estimated in Busan during 2013. Total biogenic isoprene emission in Busan during 2013 was estimated to be $4,434ton\;yr^{-1}$ with the highest emission (e.g., $28ton\;day^{-1}$) in summer using a BEIS method. Seasonal ozone production rates by isoprene ranged from 0.15 (winter) to 2.08 (summer) $ppb\;hr^{-1}$, contributing the predominant portion to ambient ozone levels. Total emissions of NOx and VOCs from ship traversing Busan ports were estimated to be 29,537 and $814ton\;yr^{-1}$, respectively, showing the significant contribution to total NOx emission in Busan. The emissions of ozone precursors were significantly different depending on ship tonnage and port location. Compared to the ship emission, the emissions of NOx and VOCs from the shipping container trucks in Busan were insignificant (2.9% for NOx and 3.9% for VOCs). Total NOx and VOCs emissions from the cargo handling equipment were estimated to be 1,440 and $133ton\;yr^{-1}$, respectively with the predominance of yard tractors.

• Journal of Electrical Engineering and Technology
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• v.12 no.4
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• pp.1406-1416
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• 2017

In complex and large-scale industries, properly designed fault detection and identification (FDI) systems considerably improve safety, reliability and availability of target processes. In thermal power plants (TPPs), generating units operate under very dangerous conditions; system failures can cause severe loss of life and property. In this paper, we propose a bagged auto-associative kernel regression (AAKR)-based FDI approach for steam boilers in TPPs. AAKR estimates new query vectors by online local modeling, and is suitable for TPPs operating under various load levels. By combining the bagging method, more stable and reliable estimations can be achieved, since the effects of random fluctuations decrease because of ensemble averaging. To validate performance, the proposed method and comparison methods (i.e., a clustering-based method and principal component analysis) are applied to failure data due to water wall tube leakage gathered from a 250 MW coal-fired TPP. Experimental results show that the proposed method fulfills reasonable false alarm rates and, at the same time, achieves better fault detection performance than the comparison methods. After performing fault detection, contribution analysis is carried out to identify fault variables; this helps operators to confirm the types of faults and efficiently take preventive actions.

• Korean Journal of Human Ecology
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• v.12 no.1
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• pp.1-13
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• 2003

The purpose of this study was to explore the effects of the attachment to mothers and peers and the depression on the adolescent delinquency. The subjects were 516 eleventh grade students in the liberal and the commercial high schools in Busan. The subjects rated on questionnaires by themselves regarding the attachment to mothers and peers, the depression and the latent delinquency. The major findings of this study were as follows: 1) Adolescents in the commercial high school had more delinquency rate than those in the liberal high school. And the male adolescent had more delinquency rate than the female one. 2) The attachment to mothers and the kind of high school attended significantly predicted the male adolescent's depression. The attachment to mothers and peers significantly predicted the depression of the female adolescent. The relative influence of the attachment to mothers on the prediction of male and female adolescent's depression was the strongest among all the varibles. 3) The kind of high school had a first direct effect on the male and female adolescent's delinquency rates and was the first contribution factor. The attachment to mothers had both direct and indirect negative effect for female and an indirect negative effect for male on the adolescent delinquency rate through depression. But the attachment to peers had a direct positive effect on both male and female adolescent's delinquency. Depression had a direct effect on male adolescent delinquency.

• Journal of Korea Multimedia Society
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• v.5 no.6
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• pp.704-711
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• 2002

Multimedia communication systems are characterized by supporting three different typer of services such as circuit switched services, and packet switched real Lime and non real time services. The wireless channels in a cell ate allocated by calls of these different service classes and the different service requirements have to be met. SRN is an extension of stochastic Petri nets and provides compact Modeling facilities for system analysis. To get the performance index, appropriate reward rates are assigned to its SRN. In this paper, we present a SRN model for performance analysis of channel allocation of multimedia mobile communication systems. The key contribution of this paper constitutes the Petri nets modeling techniques instead of complicate numerical analysis of Markov chains and easy way of performance analysis for channel allocations under SRN rewards concepts.

• Journal of Korea Technology Innovation Society
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• v.5 no.2
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• pp.245-256
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• 2002

Measurement standards, as being widely recognized, is necessary for national economic development and advanced industrialization. Also measurement standards give reliability and fair trade to the producers and consumers. Macro-effect of measurement standards using estimation of cost function has four effects: 1) value-added causing effect, 2) effect of employment, 3) reduction effect transaction cost, 4) reduction effect defect rates. In this study, to investigate the impacts between specific and the other industries, we used I-O Table of Korea Bank. The relation between the value-added produced by original production factors and final use is determined through production level, and the relation can be investigated with production causing coefficient matrix. In this study, it was showed that the measurement standards investments including measurement only man power of industries were increased from 1995 rapidly. The establishment and maintenance of measurement standards contributes to reduce the defect rate of products in production process and improve the confidence of the product quality. The results from this study show that measurement technology contributes to improve quality, decrease defect rate, improve production process, develope new products, reduce prime cost and increase the consumer's confidence on the firms. Since these results indicate that measurement standards are very important in the point of their vast contribution, we hope our findings can contribute to encourage measurement activities in industries.

• Journal of the Korean Society of School Health
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• v.7 no.1
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• pp.29-36
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• 1994

The purpose of this study was to explain the performance pattern of health education and related factors in elementary school. The data were collected from school nurses who have been working elementary school. Sample of 77 were analyzed by percent distribution, ${\chi}^2$-test, discriminant analysis. The performance rates of health education was 74%, Only 19% of total carried out health education of 6 hours per week. Important variables that was showed significant association with health education level were as follows: Perception of importance about health education among personal characteristics of school nurses and size of school c1ass, cooperation level of school administrator, operation method of school health clinic, the difficulty of school health clinic among school organization characteristics. The canonical correlation between the health education (yes or no) and important independent variables was 0.52. Among them, operation method of school health clinic. perceiveness of health education, size of school class represented the significant contribution (canonical coefficient: 0.66, 0.54, 0.52) to school health education. These findings suggest that structure and management variables of school organization are more important than personal variables of school nurses related to activation of school health education. Therefore, it is expected that the quantity and quality improvement of school health education be able to accomplish through the systematic support of school organization and government demension.