• Transactions on Electrical and Electronic Materials
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• v.16 no.3
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• pp.162-167
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• 2015

To investigate the effect of fluoro groups substitution on poly(p-phenylenevinylene) derivatives, poly(2,3,5,6- tetrafluoro-p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCTF-PPV, and poly[2,3,5,6-tetrafluoro-p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], PMTF-PPV, were synthesized by the well-known Wittig condensation polymerization process. To compare the influences of fluoro groups, no fluoro groups containing model polymers, poly(p-phenylenevinylene-alt-N-ethylhexyl-3,6-carbazolevinylene), PCPPPV and poly[p-phenylenevinylene-alt-2-methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene], p-PMEH-PPV, were also synthesized. The resulting polymers were completely soluble in common organic solvents and exhibited good thermal stability up to 300℃. The polymers showed UV-visible absorbance and photoluminescence (PL) in the ranges of 259~452 nm and 500~580 nm, respectively. The tetrafluorophenyl containing PCTF-PPV and PMTF-PPV showed relatively red-shifted PL peaks at 521 nm and 580 nm, respectively, compared to that of non-fluoro groups containing polymers (PCP-PPV: 500 nm and p-PMEH-PPV: 539 nm). The single-layer light-emitting diode was fabricated in a configuration of ITO/polymer/Al. Electroluminescene (EL) emissions of PCP-PPV, PCTF-PPV, p-PMEH-PPV and PMTF-PPV were shown at 507, 524, 556, and 616 nm, respectively.

• Journal of Distribution Science
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• v.12 no.2
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• pp.59-71
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• 2014

Purpose - In recent years, many firms have attempted various approaches to cope with the continual increase of aviation transportation. The previous research into freight charge forecasting models has focused on regression analyses using a few influence factors to calculate the future price. However, these approaches have limitations that make them difficult to apply into practice: They cannot respond promptly to small price changes and their predictive power is relatively low. Therefore, the current study proposes a freight charge-forecasting model using time series data instead a regression approach. The main purposes of this study can thus be summarized as follows. First, a proper model for freight charge using the autoregressive integrated moving average (ARIMA) model, which is mainly used for time series forecast, is presented. Second, a modified ARIMA model for freight charge prediction and the standard process of determining freight charge based on the model is presented. Third, a straightforward freight charge prediction model for practitioners to apply and utilize is presented. Research design, data, and methodology - To develop a new freight charge model, this study proposes the ARIMAC(p,q) model, which applies time difference constantly to address the correlation coefficient (autocorrelation function and partial autocorrelation function) problem as it appears in the ARIMA(p,q) model and materialize an error-adjusted ARIMAC(p,q). Cargo Account Settlement Systems (CASS) data from the International Air Transport Association (IATA) are used to predict the air freight charge. In the modeling, freight charge data for 72 months (from January 2006 to December 2011) are used for the training set, and a prediction interval of 23 months (from January 2012 to November 2013) is used for the validation set. The freight charge from November 2012 to November 2013 is predicted for three routes - Los Angeles, Miami, and Vienna - and the accuracy of the prediction interval is analyzed using mean absolute percentage error (MAPE). Results - The result of the proposed model shows better accuracy of prediction because the MAPE of the error-adjusted ARIMAC model is 10% and the MAPE of ARIMAC is 11.2% for the L.A. route. For the Miami route, the proposed model also shows slightly better accuracy in that the MAPE of the error-adjusted ARIMAC model is 3.5%, while that of ARIMAC is 3.7%. However, for the Vienna route, the accuracy of ARIMAC is better because the MAPE of ARIMAC is 14.5% and the MAPE of the error-adjusted ARIMAC model is 15.7%. Conclusions - The accuracy of the error-adjusted ARIMAC model appears better when a route's freight charge variance is large, and the accuracy of ARIMA is better when the freight charge variance is small or has a trend of ascent or descent. From the results, it can be concluded that the ARIMAC model, which uses moving averages, has less predictive power for small price changes, while the error-adjusted ARIMAC model, which uses error correction, has the advantage of being able to respond to price changes quickly.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.43-48
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• 2005

To search of a new porcine pheromonal odorants for biostimulation control system technologies to offer a potentially useful and practical way to improve reproductive efficiency in livestock species, the holographic quantitative structure activity relationship (HQSAR) model between odorants, 2-phenoxytetrahydrofurane (A), 2-cyclohexyl-oxytetrahydrofurane (B), derivatives and binding affinity constants (p[Od.]/sub 50/) for porcine odorant-binding protein (pOBP) as receptor of pig pheromones were derivated and disscused. The binding affinity constants of cyclohexyl substituents (A) for pOBP were higher (A>B) than that of phenyl substituents (B). It was revealed that the optimum HQSAR model XI using PLS analyses had a fragment length (5∼8) with chirality at 5 components and hologram length 97 bin, which had a cross-validated q²(predictablities) of 0.916, and a conventional correlation coefficient r² (fitness) of 0.988, respectively. From the atomic contribution, the C3 and C5 atom in 2-oxyfuryl group contributed to binding affinity constants, whereas the central carbon atom in tert-butyl group on the cyclohexyl ring and the C4 atom of furyl group parts showed no contribution.

• The Journal of Korean Society for School & Community Health Education
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• v.15 no.1
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• pp.121-140
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• 2014

Objectives: Recently, the rate of death by chronic disease, is increasing steadily. To prevent this, the public health center will have taken a leading role in the local community medical business through an establish to the national health promotion act and an amendment to the law of public health center in Korea. Results: Accordingly this research, using the Pender's health promotion model which is related with subject health behavior who government employees serve at the public health center have taken important position in the local community health promotion, have comprehended the actual condition of health behavior. For increasing the health behavior practice of subject to comprehend the factor which have effect on health behavior practice, which can be a correct role model in the local community health promotion. A survey was performed on 406 government employees who serve at five public health centers in Seoul. The period of survey was from 25th October, 2010 to 15th November, 2010. The results of this study were summarized as below. 1. Work-related stress, perceptible beneficial obstacle, and self-efficacy were composed by 5 points measure. The results show those work-related stress were $3.06{\pm}0.469$, 74perceptible beneficial obstacle were $3.74{\pm}0.471$, and self-efficacy were $3.49{\pm}0.469$. 2. As for the health behavior by general characteristic, the results have specific differences on age, education level, state of marriage, rank of the position, field of the occupation and employment forms in statics analysis. 3. As for the past health behavior by health behavior characteristic, work-related stress have specific differences on the past frequency of drinking (p<.05) in statics analysis, perceptible beneficial obstacle have specific differences on the past frequency of having breakfast(p<.05), having snacks(p<.05) and doing exercise(p<.05) in statics analysis. Self-efficacy have specific difference on the past frequency drinking(p<.01) in statics analysis. 4. According to the correlation between the factors related with health behavior and health behavior, the health behavior have specific differences on perceptible health condition(p<.01), the past health behavior and perceptible beneficial obstacle(p<.05). Work-related stress and self-efficacy don't have specific relation in health behavior practice. 5. The factors, which effect on health behavior practice have specific differences on the past health behavior, employment forms and field of the occupations. The ability of explanation occupied 54.8% what explained of the health behavior practice by general characteristic, perceptible health condition, employment forms and perceptible beneficial obstacle. Conclusions: According to the correlation between the factors related with health behavior, the health behavior have specific differences on perceptible health condition(p<.01), the past health behavior and perceptible beneficial obstacle(p<.05). The factors, which effect on health behavior practice have specific differences on the past health behavior, employment forms and field of the occupations.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.16
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• pp.7111-7115
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• 2015

Background: The aim of the meta-analysis was to derive a more precise assessment of the association between p16 promoter methylation and thyroid cancer risk. Materials and Methods: The PubMed, Web of Science databases and Chinese CNKI were searched for relevant articles. Ultimately, seventeen case-control studies were included with a total of 804 thyroid cancer cases and 487 controls analysis by R Software (R version 3.1.2) including meta. Crude odds ratios with 95% confidence intervals were calculated using the random-effects model which were used to assess the strength of relationship between p16 methylation and lung carcinogenesis. Funnel plots were carried out to evaluate publication bias. Results: The meta-analysis results showed that the frequency of p16 promoter methylation in cancer tissue/blood was significantly higher than that normal tissue/blood (OR=5.46, 95%CI 3.12-9.55, P<0.0001) by random effects model with small heterogeneity. Conclusions: Thus, p16 promoter methylation may be associated with thyroid cancer risk.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.445-454
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• 2002

3-D P-wave velocity model in the southern Korean Peninsula is investigated by using the earthquake tomography method. This velocity model would be used to locate the exact hypocenter position, and also useful for our understanding of the crustal structure. The simultaneous inversion is used to get the minimum 1-D model and hypo-center relocation, which are used as an initial 3-D velocity model. The velocities in the minimum 1-D model are 6.04 km/s, 6.45 km/s, and 7.78 km/s between the depth of 0-19 km, 19-32 km, and 32-55 km respectively. In the 3-D P-wave velocity model, Layer 1 (0~3 km) has high velocities in Kyongsang basin, Yonglam massif, and Okchon folded belt, and low velocities in Kyonggi massif. In layer 2 (3~19 km) high velocities are predominent around Kyonsang basin and Yongnam massif except Yonil basin, but low velocities exist around Kyonggi massif and Okchon folded belt. In Laye. 3 (19~32 km) high velocities prevail throughout the southern part of Korean Peninsula, but low velocity does throughout the middle except SNU, YIN station in Konggi massif. In Layer 4 (32 km), the maximum velocity is showed in the middle and southwestern part, while the minimum velocity in the southeastern and coastal area. The depth of the velocity boundary corresponds to the crustal structure of the southern Korean Peninsula which is calculated by gravity data.

• Environmental Engineering Research
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• v.11 no.5
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• pp.241-249
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• 2006

A mathematical model is described for the prediction of convective upward transport of an organic solvent driven by evaporation at the surface, which is known as the major transport mechanism in the in-situ photolysis of a soil contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin(TCDD). A finite-element model was proposed to incorporate the effects of multiphase flow on the distribution of each fluid, gravity as a driving force, and the use of hysteretic models for more accurate description of k-S-p relations. Extensive numerical calculations were performed to study fluid flow through three types of soils under different water table conditions. Predictions of relative permeability-saturation-pressure (k-S-p) relations and fluids distribution for an illustrative soil indicate that hysteresis effects may be quite substantial. This result emphasizes the need to use hysteretic models in performing flow simulations including reversals of flow paths. Results of additional calculations accounting for hysteresis on the one-dimensional unsaturated soil columns show that gravity affects significantly on the flow of each fluid during gravity drainage, solvent injection, and evaporation, especially for highly permeable soils. The rate and duration of solvent injection also have a profound influence on the fluid saturation profile and the amount of evaporated solvent. Key factors influencing water drainage and solvent evaporation in soils also include hydraulic conductivity and water table configuration.

• Polymer(Korea)
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• v.37 no.2
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• pp.135-140
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• 2013

The stress relaxation of poly(methyl acrylate)-poly(acrylonitrile) copolymer samples was carried out in air, distilled water, pH 3, 7 and 11 solutions at various temperatures using a tensile tester equipped with a solvent chamber. The relaxation spectra of poly(methyl acrylate)-poly(acrylonitrile) copolymers were obtained by applying the experimental stress relaxation curves to the equation of relaxation spectrum derived from the Ree-Eyring and Maxwell model. The determination of relaxation spectra was performed from computer calculation using a Laplace transform method. It was observed that the relaxation spectra of these samples are directly related to the distribution of molecular weights and self-diffusions of flow segments.

• Journal of Korean society of Dental Hygiene
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• v.20 no.4
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• pp.435-445
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• 2020

Objectives: This study investigated the relationship between obesity and dental caries of Korean adolescents. Methods: Data from the Korea National Health and Nutrition Examination Survey (KNHNES VI) (2013 to 2015) were used and targeted adolescents aged 13 to 18 years. For statistical analysis, the SPSS 18.0 program was used, and the significance level was set at 0.05. Results: For the general and health-related characteristics, female students (p=0.001) showed higher decayed, missing, and filled teeth (DMFT) index than male students. Furthermore, DMFT showed higher tendency, as age was higher (p<0.001). Smoking (p=0.011) and drinking experience (p=0.027) revealed higher DMFT. The dental caries experience was significantly different among students who were female (p=0.033), older (p=0.001), and overweight or underweight (p=0.022). In the BMI for the general and health-related characteristics, male students had higher obesity rate than female students (p=0.003), and obese subjects had higher dental checkup in the last year (p=0.013). In multiple linear regression analysis of obesity and DMFT, the unadjusted model showed that the obesity group's DMFT was about 0.8 higher than that of the normal group (p=0.024). However, statistical significance was not shown in the adjusted models. In the logistic regression analysis of obesity and dental caries experience, the unadjusted model 1 (1.93 times), the adjusted model 2 (1.79 times), and model 3 (1.76 times) showed significantly higher dental caries experience. Conclusions: Both obesity and dental caries are related to diet habits and lifestyles and have a negative impact on adult health. Therefore, it is necessary to create a healthy social environment around the adolescent, and proper intervention through education is required to form healthy habits.

• Journal of Practical Engineering Education
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• v.15 no.1
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• pp.89-95
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• 2023

This study is a descriptive research study to analyze the effects of grit in nursing students on self-directed learning ability and adjustment to university life. Data was collected from 260 nursing students including first and second-year nursing students in Region C University. The data was analyzed to find relationships among grit, self-directed learning ability, and college life adjustment using frequency analysis, descriptive statistics, t-test, ANOVA, and multiple regression analysis. The results showed the subdomains of grit in which grit in nursing students affected self-directed learning ability were consistency of interest (t=2.423, p<.05) and perseverance of effort (t=3.761, p<.001). The explanation power of the regression model was 40.2%, which was a statistically significant result (F=23.609, p<.001). The subdomains of grit in which grit in nursing students affected adjustment to college life were the consistency of interest (t=3.112, p<.001) and perseverance of effort (t=3.930, p<.001). The explanation power of the regression model was 43.2%, which was a statistically significant result (F=30.608, p<.001). These results show that it is necessary to develop educational programs to enhance individual nursing students' grit, self-directed learning ability, and college-life adjustment.