• Fire Science and Engineering
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• v.33 no.5
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• pp.1-6
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• 2019

The recent development of biofuel production technology facilitates the widespread use of bioethanol and biodiesel by mixing them with fossil fuels. However, the use of these new blended fuels in combustion could result in severe safety problems, such as fire and explosion. In this study, numerical simulation was performed on the well-stirred reactor (WSR) to simulate the autoignition temperature (AIT) in homogeneous combustion and clarify the effect of ethanol addition on the AIT, the most important property for assessing the potential for fire and explosion. Response surface methodology (RSM) was introduced as a design of experiment (DOE), enabling the AIT to be predicted and optimized systematically with respect to three independent variables: ethanol mole fraction, equivalence ratio, and pressure. The results show that the autoignition temperature primarily depends on the ethanol mole fraction and pressure, while the effects of the equivalence ratio are independent of the AIT. RSM accurately predicted the experimental AIT, indicating that this method can be used to effectively predict the key properties involved in fires and explosions.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.49 no.2
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• pp.1-6
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• 2012

In recent years global climate change of hurricanes and torrential rains are going to significantly, that increase damages to property and human life. The disasters have been several claimed in every field. In future, climate changes blowing are keen to strike released to the world like in several movies. Reducing the damage of long-term weather phenomena are emerging with predicting changes in weather. In this study, it is shown how to predict the red tide phenomenon with multiple linear regression analysis and artificial neural network techniques. The red tide phenomenon causing risk could be reduced by filtering sensor data which are transmitted and forecasted in real time. It could be ubiquitous driven custom marine information service system, and forecasting techniques to use throughout the meteorological disasters to minimize damage.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.195-202
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• 2016

In general, piston pumps are frequently used for concrete pumping. Filling coefficient signifies the ratio volume of a hydraulic cylinder to volume of concrete inside the cylinder. Therefore, it may be considered as a parameter directly affecting the flow rate and efficiency for concrete pumping. However, accurate analyses on this aspect have not yet been performed. In this paper, the data measured from horizontal pipeline pumping tests for 350m and 548m in length was analyzed to identify the relationships of rheological properties of concrete and stroke time with the filling coefficient. In addition, an equation allowing prediction of the filling coefficient from rheological properties of concrete and stroke time has been suggested.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.37-44
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• 2002

A theoretical study of spray and combustion characteristics due to coaxial twin-fluid injection is conducted to investigate the effects of liquid jet property, droplet size, contact length and liquid jet velocity. Model is properly validated with measurements and shows good agreement. Prediction of jet contact length, droplet size, liquid jet velocity reflects genuine features of coaxial injection in physical and practical aspects. Both the jet contact length and tile droplet size are reduced in a linear manner with an increase of injector diameter. Cross sectional area of liquid intact core is reduced with augmented jet splitting rate, thus the jet is accelerated to maintain the mass continuity and with an assistant of momentum diffusion by burnt gas.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.378-383
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• 2008

In December 2006, the Ministry of Environment Republic of Korea established the guideline which is "Indoor Air Quality Management Guidelines in Public Transportation." as control items, $CO_2$ (carbon dioxide) and PM10 (particle matter) are classified two categories, that is, Level 1 (non-rush hour), Level 2 (rush hour). Therefore, the quality of air in train and subway should be controlled in accordance with the guideline. We took a measure the air freshness inside train twice at Line 4 (Tangogae-Oido), in Sep. 2007 and at Line 1 (Dongincheon-Yongsan) in Nov. 2007, respectively and, also expected the emitted $CO_2$ concentration by using a property of matter such as EMU (Electric Multiple Unit) design reviewing specification and air. According to the measured values, the concentration of PM10 was 44, 57, 45% and the concentration of $CO_2$ was 39, 36, 44% respectively, all measured values are within the guideline and also, as a result we found the expected value and measured value are similar.

• Journal of the Korean Geographical Society
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• v.51 no.2
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• pp.219-233
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• 2016

In social science fields, statistical models are used almost exclusively for causal explanation, and explanatory modeling has been a mainstream until now. In contrast, predictive modeling has been rare in the fields. Hence, we focus on constructing the predictive non-parametric model, instead of the explanatory model. Gangnam-gu, Seoul was chosen as a study area and we collected single-family house sales data sold between 2011 and 2014. We applied non-parametric models proposed in machine learning area including generalized additive model(GAM), random forest, multivariate adaptive regression splines(MARS) and support vector machines(SVM). Models developed recently such as MARS and SVM were found to be superior in predictive power for house price estimation. Finally, spatial autocorrelation was accounted for in the non-parametric models additionally, and the result showed that their predictive power was enhanced further. We hope that this study will prompt methodology for property price estimation to be extended from traditional parametric models into non-parametric ones.

• Research in Community and Public Health Nursing
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• v.12 no.1
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• pp.142-149
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• 2001

The health education for elementary school students is a very important factor in the development of adult health practices. Particularly, eyesight is difficult to recover if lost. Therefore, prevention is better than cure. This study was conducted to investigate the factors that affect the visual health behavior of elementary school students and to furnish basic materials and directions for the promotion of elementary school health. The investigation was carried out for 4 days from 9. 18. 2000 to 9. 21. 2000 for 199 children in 3 elementary schools. A questionnaire was composed of 3 questions about general property. 20 questions about visual health behavior. 7 questions about visual self-efficacy. 5 questions about visual motivation. 16 questions about self-conception. 20 questions about the health locus of control. The data was analysed by an SAS program for t-test. ANOVA. correlation, and multiple regression tests. The results are as follows. 1. The visual health behavior of elementary school children was good (average 52.53). 2. For visual health behavior, school, year, and sex were influential factors. economic levels were not. 3. Visual health behavior had a significant correlation with visual self-efficacy, visual health motives and self-conception. but not with the locus of control. 4. In the multiple regression test, visual self-efficacy and self-conception were significant prediction factors -- the suitability of the regression model was 30.8%. Suggestions from the results are as follows: First, school year and sex had a significant influence on visual health behavior: therefore, it is necessary to consider these two factors when education programs are developed. Second, this study was carried out for students in a partial area only. Therefore, repeated studies for a large sample are necessary for the future.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.419-431
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• 2012

This paper takes precautions proposals against prospective disasters from the space weather maximum in 2013. A geomagnetic space storm sparked by a solar maximum like the one that flared toward earth is bound to strike again and could wreak havoc across the modern world. The purpose of the study is that the disaster reduction and safety service implementation study on the ultimate space weather systems by the information systems of the space weather. The process methods of the study are that an implementation of preparation for the smart IT and GIS based disaster management systems of the solar maximum deal with analysis on the flare, solar proton event, and geomagnetic storm from space blasters, These approach and methods for the solar maximin display national policy implementation of the pattern of the radio wave disasters from the protection and preparation methods. This research can provide affective methods for the saving lives and property protections that implementation of the disaster prediction and disaster prevention systems adapts the smart IT systems and converged decision making support systems using uGIS methodology.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.2
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• pp.111-117
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• 2019

An experimental study on the welding part of a heat transfer plate that constitutes the lightweight and high efficiency recuperator is presented in this paper. In particular, to find out the service life of the welded part, fatigue characteristics were determined through experiments. Experiments were carried out on two materials (STS347, AL20-25 + nb), which are selected as the material of the recuperator; further, the specimens were manufactured through the methods used for actual fabrication and the standards recommended by ASTM. To evaluate the mechanical properties of the specimens at room and high temperature, MTS-810 was used in a high-temperature furnace. The tensile test was carried out at room and high temperatures for each specimen. The fatigue test was carried out by setting the load ratio corresponding to 50%, 40%, 30%, 20%, and 10% of the tensile strength at the stress ratio of 0.1. Finally, the fatigue life characteristics obtained by the experiment were compared with the stresses owing to the load generated in the operating conditions of the recuperator, and the lifetime of the welds was evaluated to prepare for the operation time required by the UAV.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.22-32
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• 2019

On offshore platforms, oil and gas leaks are apt to be the initial events of major accidents that may result in significant loss of life and property damage. To prevent accidents induced by leakage, it is vital to perform a case-specific and accurate risk assessment. This paper presents an integrated method of Ddynamic Qquantitative Rrisk Aassessment (DQRA)-using the Decision Making Trial and Evaluation Laboratory (DEMATEL)-Bayesian Network (BN)-for evaluation of the system vulnerabilities and prediction of the occurrence probabilities of accidents induced by leakage. In the method, three-level indicators are established to identify factors, events, and subsystems that may lead to leakage, fire, and explosion. The critical indicators that directly influence the evolution of risk are identified using DEMATEL. Then, a sequential model is developed to describe the escalation of initial events using an Event Tree (ET), which is converted into a BN to calculate the posterior probabilities of indicators. Using the newly introduced accident precursor data, the failure probabilities of safety barriers and basic factors, and the occurrence probabilities of different consequences can be updated using the BN. The proposed method overcomes the limitations of traditional methods that cannot effectively utilize the operational data of platforms. This work shows trends of accident risks over time and provides useful information for risk control of floating marine platforms.