• Journal of the Korean Society of Combustion
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• v.22 no.4
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• pp.27-34
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• 2017

Various approaches have been proposed to predict the ash deposition (slagging and fouling) propensity of coal, which is essential in maintaining high efficiency and preventing corrosion/damage of a coal-fired boiler. The common method is to establish an index of the ash deposition propensity based on elementary coal composition and advanced characterization of ash properties, which is readily applicable to design, operation and maintenance of coal-fired boilers. Although many indexes have been developed for this purpose, their validity is still not satisfactory in actual applications to particular coal types or operating conditions. This paper reviews the status of predictive approaches for the ash deposition propensity, and assesses the performance of existing indexes by comparing the results for selected coals. This work will contribute to the development of a comprehensive and practical method for prediction of the ash deposition propensity.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.45 no.1
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• pp.71-82
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• 2022

Most of the predictions using machine learning are neutral predictions considering the symmetrical situation where the predicted value is not smaller or larger than the actual value. However, in some situations, asymmetric prediction such as over-prediction or under-prediction may be better than neutral prediction, and it can induce better judgment by providing various predictions to decision makers. A method called Asymmetric Twin Support Vector Regression (ATSVR) using TSVR(Twin Support Vector Regression), which has a fast calculation time, was proposed by controlling the asymmetry of the upper and lower widths of the ε-tube and the asymmetry of the penalty with two parameters. In addition, by applying the existing GSVQR and the proposed ATSVR, prediction using the prediction propensities of over-prediction, under-prediction, and neutral prediction was performed. When two parameters were used for both GSVQR and ATSVR, it was possible to predict according to the prediction propensity, and ATSVR was found to be more than twice as fast in terms of calculation time. On the other hand, in terms of accuracy, there was no significant difference between ATSVR and GSVQR, but it was found that GSVQR reflected the prediction propensity better than ATSVR when checking the figures. The accuracy of under-prediction or over-prediction was lower than that of neutral prediction. It seems that using both parameters rather than using one of the two parameters (p_1,p_2) increases the change in the prediction tendency. However, depending on the situation, it may be better to use only one of the two parameters.

• Communications for Statistical Applications and Methods
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• v.16 no.1
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• pp.103-113
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• 2009

Weighting is a common form of unit nonresponse adjustment in sample surveys where entire questionnaires are missing due to noncontact or refusal to participate. A common approach computes the response weight as the inverse of the response rate within adjustment cells based on covariate information. In this paper, we consider the efficiency and robustness of nonresponse weight adjustment bated on the response propensity and predictive mean. In the simulation study based on 2000 Fishry Census in Korea, the root mean squared errors for assessing the various ways of forming nonresponse adjustment cell s are investigated. The simulation result suggest that the most important feature of variables for inclusion in weighting adjustment is that they are predictive of survey outcomes. Though useful, prediction of the propensity to response is a secondary. Also the result suggest that adjustment cells based on joint classification by the response propensity and predictor of the outcomes is productive.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.4D
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• pp.313-322
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• 2012

This study analyzes taxi driver's risk-taking propensity with respect to risk-taking behaviour and traffic locus of control. In order to explore the traffic risk-taking, we present a predictive model by structural analysis of driver's risk-taking propensity. By applying this model to survey data from taxi drivers, we can observe that driver's risk-taking propensity has a significant impact on the traffic violation intention, and the higher perception of law and the lower lack of law-abiding drivers have, the more they tend to violate. Second, we test using multivariate analysis if the level of risk-taking propensity differs by the locus of control( external or internal). Drivers of external control shows higher risk-taking level compared to those of internal control so that the risk-taking propensity shows difference according to the locus of control for the responsibility of traffic accidents. The structural equation model of our study yielded ${\chi}^2$ = 279.7, ${\chi}^2$/df = 1.55, RMSEA = 0.44, GFI = 0.911, TLI = 0.916, CFI = 0.929.

• The Journal of Korean Society for School & Community Health Education
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• v.22 no.2
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• pp.1-14
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• 2021

Objectives: The study aimed to analyze the effects of household financial difficulties caused by COVID-19 (2019 coronavirus disease) on suicidal tendencies of adolescents. Methods: We selected 54,948 middle and high school students who were surveyed based on the Korean Youth Risk Behavior Web-based Survey 2020. To analyze the data, we used the STATA 16.0 program to conduct propensity score matching (PSM). Results: After controlling for selection effects by using PSM, the household financial difficulties caused by COVID-19 maintained a significant predictive effect on increasing suicidal ideation, suicide attempts, and decreasing tendency in hospital-treated after suicide attempts. However, depressive symptoms and suicide plan did not show a significant correlation with household financial difficulties associated with COVID-19. Conclusions: It was found that the rate of suicidal ideation and suicide attempts among adolescents who experienced a household financial difficulties due to COVID-19. Therefore, It can provide empirical evidence for estimating the impact of COVID-19 on adolescent suicide rates.

• Survey Research
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• v.9 no.1
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• pp.87-100
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• 2008

We calculated the predictive interval for the number of seats belonging to major political parties in the case of the 2004 General Election of Korea, using Bayesian frame of inference. Moreover, we proposed the adjustment procedure for correcting the minor group's propensity of refusal or nonresponse due to effect of the spiral of silence.

• Journal of the Korean Home Economics Association
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• v.34 no.4
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• pp.103-117
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• 1996

This study is a theoretical approach by literature about life style and housing life style. The purpose of this research is making an analysis model of housing life style which can be used as a conceptual framework in empirical study. the theme of‘Life style’was studied mainly in the area of consumerism and housing. Model was made to explore the sub-domain of new analysis model by the microsociological approach. As results, 1) Independent variable of housing life style research model must be selected to be possible of comparison in effect of objective and subjective variable and in effect of predictive function and well-being function of housing life style. 2) Sub-domain of housing life style must be consisted of value orientation of family life, consumption in house, consumer durables, furniture., and propensity to using space. 3) Conceptual model of housing life style must be tested in empirical study to know what is the housing adjustment behavior of individual family, to improve quality of housing life and to suggest housing policy for family as a consumer.

• International Journal of Advanced Culture Technology
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• v.11 no.3
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• pp.190-198
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• 2023

Sentiment analysis can be applied to all texts generated from websites, blogs, messengers, etc. The study fulfills an artificial intelligence sentiment analysis estimating visiting evaluation opinions (reviews) and visitor ratings, and suggests a deep learning model which foretells either an affirmative or a negative inclination for new reviews. This study operates review big data about Jeju tourist attractions which are extracted from Google from October 1st, 2021 to November 30th, 2021. The normalization data used in the propensity prediction modeling of this study were divided into training data and test data at a 7.5:2.5 ratio, and the CNN classification neural network was used for learning. The predictive model of the research indicates an accuracy of approximately 84.72%, which shows that it can upgrade performance in the future as evaluating its error rate and learning precision.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.1789-1795
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• 2016

Background: Breast cancer is the commonest female cancer worldwide and its propensity to metastasize negatively impacts on therapeutic outcome. Several clinicopathological parameters with prognostic/predictive significance have been associated with metastatic suppressor expression levels. The role of metastatic suppressor gene (MSG) KiSS1 in breast cancer remains unclear. Our goal was to investigate the possible clinical significance of KiSS1 breast cancer. Materials and Methods: The study was conducted on 87 histologically proven cases of breast cancer and background normal tiisue. Quantitative reverse transcriptase polymerase chain reaction (qRT PCR) and immunohistochemistry (IHC) were used to investigate KiSS1 at gene and protein levels, respectively, for correlation with several patient characteristics including age, family history, hormonal receptor status, stage, tumor size, nodal involvement and metastatic manifestation and finally with median overall survival (OS). Results: Our study revealed (i) KiSS1 levels were generally elevated in breast cancer vs normal tissue (P < 0.05). (ii) however, a statistically significant lower expression of KiSS1 was observed in metastatic vs non metastatic cases (P = 0.04). (iii) KiSS1 levels strongly correlated with T,N,M category, histological grade and advanced stage (p<0.001) but not other studied parameters. (iv) Lastly, a significant correlation between expression of KiSS1 and median OS was found (P = 0.04). Conclusions: Conclusively, less elevated KiSS1 expression is a negative prognostic factor for OS, advancing tumor stage, axillary lymph node status, metastatic propensity and advancing grade of the breast cancer patient. Patients with negative KiSS1 expression may require a more intensive therapeutic strategy.

• Radiation Oncology Journal
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• v.36 no.4
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• pp.276-284
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• 2018

Purpose: Traditionally, three-dimensional conformal radiation therapy (3D-CRT) is used for neoadjuvant chemoradiation in locally advanced rectal cancer. Intensity-modulated radiation therapy (IMRT) was later developed for more conformal dose distribution, with the potential for reduced toxicity across many disease sites. We sought to use the National Cancer Database (NCDB) to examine trends and predictors for IMRT use in rectal cancer. Materials and Methods: We queried the NCDB from 2004 to 2015 for patients with rectal adenocarcinoma treated with neoadjuvant concurrent chemoradiation to standard doses followed by surgical resection. Odds ratios were used to determine predictors of IMRT use. Univariable and multivariable Cox regressions were used to determine potential predictors of overall survival (OS). Propensity matching was used to account for any indication bias. Results: Among 21,490 eligible patients, 3,131 were treated with IMRT. IMRT use increased from 1% in 2004 to 22% in 2014. Predictors for IMRT use included increased N stage, higher comorbidity score, more recent year, treatment at an academic facility, increased income, and higher educational level. On propensity-adjusted, multivariable analysis, male gender, increased distance to facility, higher comorbidity score, IMRT technique, government insurance, African-American race, and non-metro location were predictive of worse OS. Of note, the complete response rate at time of surgery was 28% with non-IMRT and 21% with IMRT. Conclusion: IMRT use has steadily increased in the treatment of rectal cancer, but still remains only a fraction of overall treatment technique, more often reserved for higher disease burden.