• JSTS:Journal of Semiconductor Technology and Science
• /
• v.14 no.5
• /
• pp.666-672
• /
• 2014

We have investigated the gate insulator effects on the electrical performance of p-type tin monoxide (SnO) thin-film transistors (TFTs). Various SnO TFTs are fabricated with different gate insulators of a thermal $SiO_2$, a plasma-enhanced chemical vapor deposition (PECVD) $SiO_x$, a $150^{\circ}C$-deposited PEVCD $SiO_x$, and a $300^{\circ}C$-deposited PECVD $SiO_x$. Among the devices, the one with the $150^{\circ}C$-deposited PEVCD $SiO_x$ exhibits the best electrical performance including a high field-effect mobility ($=4.86cm^2/Vs$), a small subthreshold swing (=0.7 V/decade), and a turn-on voltage around 0 (V). Based on the X-ray diffraction data and the localized-trap-states model, the reduced carrier concentration and the increased carrier mobility due to the small grain size of the SnO thin-film are considered as possible mechanisms, resulting in its high electrical performance.

• Journal of the Korean Society of Groundwater Environment
• /
• v.2 no.1
• /
• pp.22-29
• /
• 1995

Mobile bacterial particles can act as carriers and enhance the transport of hydrophobic contaminants in ground water by reducing retardation effects. Because of their colloidal size and favorable surface conditions, bacteria can act as efficient contaminant carriers. When such carriers exist in a porous medium, the system can be thought of as three phases: an aqueous phase, a carrier phase, and a stationary solid matrix phase. Contaminant can be present in either or all of these phases. In this study, a mathematical model based on mass balances is developed to describe the transport and fate of biodegradable contaminant in a porous medium. Bacterial mass transfer mechanism between aqueous and solid matrix phases, and contaminant mass transfer between aqueous and bacterial phases are represented by kinetic models. Governing equations are non-dimensionalized and solved to analyze the bacteria facilitated contaminant transport. The numerical results of the facilitation effect match favorably with experimental data reported in the literature. Results show that the contaminant transport can be described by local equilibrium assumption when Damkohler numbers are larger than 10. Significant sensitivities to model parameters, particularly bacterial growth rate and influent bacterial concentration, were discovered.

• Journal of Global Scholars of Marketing Science
• /
• v.7
• /
• pp.209-238
• /
• 2001

Objectives of this study were: First, to review the effect of buyer position in power retailer on job performance and store performance. Second, to set up research model specifying relationships between the PAQ dimensions of retailer's buyer, job performance and store performance. Third, to test hypotheses derived from the research model of this study and to establish strategy for managing discount store and department store. Marketing Implications of this study were: First, buyers of power retailers should respond more actively to rapidly changing purchasing situation. Second, job content of buyers in power retailers can be redesigned based upon results of this study. Third, as the size and the length of operation of retailers increase, an innovative system should be invented to enhance the effectiveness of power retailers. Limitations of this study were: First, validity and reliability of data collection methods used in this study were questionable for the lack of past researches in Korea. Second, static research method was employed in this study. Generalization over different time interval was almost impossible from results of this study.

• International Journal of Concrete Structures and Materials
• /
• v.7 no.3
• /
• pp.225-238
• /
• 2013

In this study, a two-layer feed-forward neural network was constructed and applied to determine a mapping associating mix design and testing factors of cement-nano silica (NS)-rice husk ash ternary blended concrete samples with their performance in conductance to the water absorption properties. To generate data for the neural network model (NNM), a total of 174 field cores from 58 different mixes at three ages were tested in the laboratory for each of percentage, velocity and coefficient of water absorption and mix volumetric properties. The significant factors (six items) that affect the permeability properties of ternary blended concrete were identified by experimental studies which were: (1) percentage of cement; (2) content of rice husk ash; (3) percentage of 15 nm of $SiO_2$ particles; (4) content of NS particles with average size of 80 nm; (5) effect of curing medium and (6) curing time. The mentioned significant factors were then used to define the domain of a neural network which was trained based on the Levenberg-Marquardt back propagation algorithm using Matlab software. Excellent agreement was observed between simulation and laboratory data. It is believed that the novel developed NNM with three outputs will be a useful tool in the study of the permeability properties of ternary blended concrete and its maintenance.

• The Journal of the Korean Society for Microbiology
• /
• v.17 no.1
• /
• pp.7-14
• /
• 1982

A model of induction of neoplasia by viruses has develpoed from experimental studies in animals and in cultured cells and oncogenic transformation of cells is the result of integration of viral genetic information into the cellular DNA. The evidence for these associations was derived primarily from seroepidemiologic investigation. However, data indicating that the relation between HSV-2 and cervical cancer fits the model derived from experimental animal studies are not yet sufficient to draw conclusion with regard to the etiologic role the virus in the development of the neoplasms. In other hand, the K562 tumor cell is highly susceptible target for natural killer cell lysis by the lymphocytes of human and murine periperal blood. The characteristics of this effector cell type has been investigated. A study on natural killer cell mediated cytotoxicity(NKMC) against $^{51}Cr$-K562 as target cell was studed in HSV-2 infected ICR mouse. We have studied for susceptibility of HSV-2 against mouse embryo fibroblast(MEF) cells and NKMC from HSV-2 infected mouse. The results obtained that the mouse embryo fibroblast cells culture, the number and size of the cells were markedly increased and formed a monolayers relatively rapid, and become complete monolayer sheet around 72 hrs. Duration of cytopathic effect on MEF cells was rapid by serial passing of HSV-2. The morphology of the HSV-2 infected cells appear to be mainly round, ovium, spindle form and some of them was forming large giant cells. The NKMC was decrease in mouse with HSV-2 and comparison between effector/target cells ratio as 25:1 and 50:1 respectively, the NKMC was found to be more significantly decreased than normal control we have concluded that the natural killer cell activity of the viral infected mouse was shown as a suppressed during the HSV-2 infection, day 7th and 14th.

• Journal of Biomedical Engineering Research
• /
• v.38 no.6
• /
• pp.313-320
• /
• 2017

Myocardial infarction is a disease caused by stenosis of the coronary arteries. The high risk of sudden cardiac death due to myocardial infarction has triggered related researches that have been actively studied so far. However, these studies focused on the clinical results, which are mainly based on observations of symptoms due to infarction through electrocardiograms. Therefore, in this study, we tried to analyze the behavior of heart according to the position and volume of infarction lesion through the computer simulation study using three dimensional ventricular models. In order to implement infarction, commercial software was used to simulate cell necrosis due to blockage of a specific coronary. In addition, the conduction block due to infarction was mimicked by reducing the electrical conduction in the infarcted area, which was 100 times less than the electrical conduction of the whole ventricular lattice implemented by the finite element analysis method. Thus, this study classified the infarcted cases into the upper, middle, lower, and apex according to lattice data of eight different infraction areas. In other words, we assumed that myocardial infarction would have inherent electro-dynamic characteristics depending on the location and extent, and analyzed the ventricular electromechanical responses for infarction lesions using a three dimensional cardiac physiome model. The results showed that the volume of infarction did not directly affect the cardiac responses, but the location of the infarction lesions could influence the ventricular pumping efficiency. These suggest that the occlusion of specific coronary arteries may have a fatal effect on the decline in ventricular performance. In conclusion, although location of myocardial infarction lesions is considered to be an important variable to be considered clinically rather than lesion size, quantitative predictions should be made more in the future considering physiological factors such as lesion location and direction of myocardial fiber at that location.

• The Journal of Information Systems
• /
• v.29 no.3
• /
• pp.145-157
• /
• 2020

Purpose This study proposed an approach for predicting the efficiency rating of the cultural tourism festivals using DEA and machine learning techniques. The cultural tourism festivals are selected for the best festivals through peer reviews by tourism experts. However, only 10% of the festivals which are held in a year could be evaluated in the view of effectiveness without considering the efficiency of festivals. Design/methodology/approach Efficiency scores were derived from the results of DEA for the prediction of efficiency ratings. This study utilized BCC models to reflect the size effect of festivals and classified the festivals into four ratings according the efficiency scores. Multi-classification method were considered to build the prediction of four ratings for the festivals in this study. We utilized neural networks and SVMs with OAO(one-against-one), OAR(one-against-rest), C&S(crammer & singer) with Korea festival data from 2013 to 2018. Findings The number of total visitors in low efficient rating of DEA is more larger than the number of total visitors in high efficient ratings although the total expenditure of visitors is the highest in the most efficient rating when we analyzed the results of DEA for the characteristics of four ratings. SVM with OAO model showed the most superior performance in accuracy as SVM with OAR model was not trained well because of the imbalanced distribution between efficient rating and the other ratings. Our approach could predict the efficiency of festivals which were not included in the review process of culture tourism festivals without rebuilding DEA models each time. This enables us to manage the festivals efficiently with the proposed machine learning models.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.4
• /
• pp.466-475
• /
• 2003

The gun-type gas burner adopted in this study is generally composed of eight slits and swirl vanes. Thus, this paper is studied to investigate the effect of slits and swirl vanes on the turbulent flow fields in the horizontal plane of gas swirl burner with a cone type baffle plate measured by using X-probe from hot-wire anemometer system. This experiment is carried out at flow rate 450 $\ell$/min in the test section of subsonic wind tunnel. The axial mean velocity component in the case of burner model with only swirl vanes shows the characteristic that spreads more remarkably toward the radial direction than axial one, it does, however, directly opposite tendency in the case of burner model with only slits. Consequently. both slits and swirl vanes composing of gun-type gas burner play an important role in decrease of the speed near slits and increase of the flow speed in the central part of a burner because the biggest speed spurted from slits encircles rotational flow by swirl vanes and it drives main flow toward the axial direction. Moreover, the turbulent intensities and turbulent kinetic energy of gun-type gas burner are distributed with a fairly bigger size within X/R<0.6410 than burner models which have only slits or swirl vanes because the rotational flow by swirl vanes and the fast jet flow by slits increase flow mixing, diffusion, and mean velocity gradient effectively.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.41 no.5
• /
• pp.409-414
• /
• 2017

In the thin strip coiling process, it is necessary to use a sleeve with a mandrel to prevent excessive deformation of the strip. The stress distribution in the sleeve and strip is an important factor to determine the size of the sleeve. However, an experimental approach is almost impossible because of the accumulation of high pressure. A finite element (FE) model of the strip coiling process was developed in this study. Then, the radial and hoop stresses on the sleeve and strip were investigated using FE analyses. The theoretical values and analysis results under idealized conditions were compared to verify the FE model. The effect of the strip thickness on the stress distribution was also investigated. The radial stress increased by 6.3 times for a 1-mm-thick strip at the coil starting point. The radial stress at the sleeve increased by 14.8 % with a stacked thickness of 90 mm because of the reaction force applied by the mandrel.

• Health Policy and Management
• /
• v.26 no.1
• /
• pp.24-29
• /
• 2016

Background: Socio-economical status, represented by poverty, is a potent factor in predicting health status, because preventable illness and death occurs due to poverty and socio-economical situation. This study aims to provide information towards on the correlation between poverty and self-rated health in consideration of elements of health behaviors and family and friend support in Philippines. Methods: Data was collected on 15th to 28th of February 2011 by using structured questionnaire through interview method. Study area is Antipolo and Tondo in Manila, Philippines. Sample size was 1,100 but only 658 cases was analyzed due to incomplete questionnaire. Results: Results show that the poverty has direct negative influence on self-rated health, while the presence of family and friend support decreased negative influence. And through the analysis of mediated moderation model, similarly poverty has also indirect negative effect on self-rated health by health behaviors and family and friend support. Especially, regular exercise was found to be a major variable that mediates poverty and self-rated health. Conclusion: In conclusion, to improve the self-rated health state of respondents need to provide emotional support especially from family and friends. Also regular exercise should be encouraged by raising health awareness through continuous health education and promotion for the residents in order to develop health behaviors.