• Journal of Oral Medicine and Pain
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• v.34 no.3
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• pp.277-294
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• 2009

The purpose of this study was to evaluate the soft tissue changes of class II adolescents and adults in respect to extraction or nonextraction. The study included 68 patients from Wonkwang Dental Hospital were categorized to adolescent extraction group, adolescent nonextraction group, adult extraction group, adult nonextraction group. Cephalometric tracing of each patient was done to compare pretreatment and posttreatment of each group, to compare the changes between groups. And among the variables that showed significancy, correlation analysis and simple linear regression were done. The results were as follows. 1. In both adolescents and adults after extraction treatment, nasolabial angle significantly increased and in both subjects after non extraction treatment, nasolabial angle significantly decreased. 2. In extraction subjects, there were positive correlation between the amount of treatment changes of vertical-U1 and E line-upper lip, the changes of vertical-L1 and E line-lower lip, the changes of vertical-L1 and vertical-Li. 3. In extraction subjects, simple regression equations of E line-upper lip, E line-lower lip, Li were calculated by regression analysis. According to the results above, it could be considered that the effect of the extraction or nonextraction treatment was greater than the effect of growth.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.252-258
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• 2007

We have studied the feasibility of geostatistics approach to enhancing analysis of sparsely obtained seismic data by combining with satellite gravity data. The shallow depth and numerous fishing nets in The Yellow Sea, west of Korea, makes it difficult to do seismic surveys in this area. Therefore, we have attempted to use geostatistics to integrate the seismic data along with gravity data. To evaluate the feasibility of this approach, we have extracted only a few seismic profile data from previous surveys in the Yellow Sea and performed integrated analysis combining with the results from gravity data under the assumption that seismic velocity and density have a high physical correlation. First, we analyzed the correlation between extracted seismic profiles and depths obtained from gravity inversion. Next, we transferred the gravity depth to travel time using non-linear indicator transform and analyze residual values by kriging with varying local means. Finally, the reconstructed time structure map was compared with the original seismic section given in the previous study. Our geostatistical approach demonstrates relatively satisfactory results and especially, in the boundary area where seismic lines are sparse, gives us more in-depth information than previously available.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.29-41
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• 2019

Terrestrial Gross Primary Production (GPP) is the largest global carbon flux, and forest ecosystems are important because of the ability to store much more significant amounts of carbon than other terrestrial ecosystems. There have been several attempts to estimate GPP using mechanism-based models. However, mechanism-based models including biological, chemical, and physical processes are limited due to a lack of flexibility in predicting non-stationary ecological processes, which are caused by a local and global change. Instead mechanism-free methods are strongly recommended to estimate nonlinear dynamics that occur in nature like GPP. Therefore, we used the mechanism-free machine learning techniques to estimate the daily GPP. In this study, support vector machine (SVM), random forest (RF) and artificial neural network (ANN) were used and compared with the traditional multiple linear regression model (LM). MODIS products and meteorological parameters from eddy covariance data were employed to train the machine learning and LM models from 2006 to 2013. GPP prediction models were compared with daily GPP from eddy covariance measurement in a deciduous forest in South Korea in 2014 and 2015. Statistical analysis including correlation coefficient (R), root mean square error (RMSE) and mean squared error (MSE) were used to evaluate the performance of models. In general, the models from machine-learning algorithms (R = 0.85 - 0.93, MSE = 1.00 - 2.05, p < 0.001) showed better performance than linear regression model (R = 0.82 - 0.92, MSE = 1.24 - 2.45, p < 0.001). These results provide insight into high predictability and the possibility of expansion through the use of the mechanism-free machine-learning models and remote sensing for predicting non-stationary ecological processes such as seasonal GPP.

• Food Science and Preservation
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• v.21 no.6
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• pp.859-865
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• 2014

This study was conducted to analyze the hydrocarbons and 2-alkylcyclobutanones as marker compounds in walnuts after the walnuts' exposure to ${\gamma}$ irradiation. The samples were irradiated with gamma rays at 0, 1, 3, 5, 7, and 10 kGy doses. The lipids were extracted via soxhlet extraction using hexane, and were separated by florisil column and identified via gas chromatography / mass spectrometry (GC/MS). The hydrocarbons that were detected were 8-heptadecene ($C_{17:1}$) and 1,7-hexadecadiene ($C_{16:2}$) from oleic acid and 8,11-heptadecadiene ($C_{17:2}$) and 1,7,10-hexadecatriene ($C_{16:3}$) from linoleic acid. The 2-alkylcyclobutanones that were detected were 2-dodecylcyclobutanone (DCB) from palmitic acid, 2-tetradecylcyclobutanone (TCB) from stearic acid, 2-(5'-tetradecenyl)cyclobutanone (TECB) from oleic acid, and 2-(5',8'-tetradecadienyl)cyclobutanone (5',8'-TCB) from linoleic acid. The correlation between the irradiation dose and the concentrations of the hydrocarbons and 2-alkylcyclobutanones in the walnuts was found to be linear. The radio-induced hydrocarbons and 2-alkylcyclobutanones were clearly detected in the irradiated walnuts at 1 kGy and above, but not in the non-irradiated ones. The major hydrocarbons obtained after irradiation were 8-heptadecene from oleic acid and 8,11-heptadecadiene and 1,7,10-hexadecatriene from linoleic acid, and the major 2-alkylcyclobutanones were TECB from oleic acid and 5',8'-TCB from linoleic acid. Therefore, these major compounds were concluded to be the marker compounds for determining the irradiated and non-irradiated samples.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.6 no.2
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• pp.272-280
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• 1996

This study was to evaluate the associations between urinary S-Phenyl-mercapturic acid(S-PMA) as a new indicator of biological monitoring for low level of exposure to benzene and independent variables such as the air concentration of benzene in the breathing zone of workers, the years of work, and smoking. In this study the subjects were the total of 145 drawn from 53 workers who were occupationally exposed to benzene and 92 workers who were not. The results were as follows: 1. In the workplace geometric mean concentration of benzene in the breathing zone of workers was 0.31 ppm(0.02 - 3.26 ppm) for the spraying workers and 0.25 ppm(0.02 - 3.95 ppm) for the printing workers. 2. The geometric mean of uninary S-PMA for non exposed group was $8.9{\mu}g/g$ creatinine($0.6-72.3{\mu}g/g$ creatinine), 80.3% (74 workers) of the total non-exposed workers indicated less than $20{\mu}g/g$ creatinine of uninary S-PMA. The difference of uninary S-PMA by sex, age, smoking was not significant. 3. The geometric mean of urinary S-PMA for workers who were exposed to benzene was $37.2{\mu}g/g$ creatinine, and was four times higher than that of workers who were not exposed. And 79.3% (42 workers) of the total exposed workers indicated more than $20{\mu}g/g$ creatinine of urinary S-PMA. 4. Regarding the level of benzene in the air, urinary S-PMA was the highest level of $147.9{\mu}g/g$ creatinine in the workers who were exposed to air concentration of 0.5 ppm of benzene and was higher as the level in the air was increased. 5. The correlation coefficient between log urinary S-PMA and log benzene concentration in the breathing zone was 0.80, and the following linear equation was found between urinary log S-PMA and log benzene concentration in the breathing zone : log S-PMA(${\mu}g/g$ creatinine) = 0.564 log benzene in air(ppm) + 0.192 (n=53, r=0.80, p=0.000) In conclusion, the concentration of S-PMA in urine proved to be good parameter for biological monitoring benzene exposure at the workplace even at low level of benzene in air.

• Ocean and Polar Research
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• v.44 no.4
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• pp.297-310
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• 2022

To understand the chemical composition of aerosols in the Cheju-Korea Straits and their contribution to the ocean by deposition, aerosol samples were collected on board R/V Eardo from November 1997 to May 1999. The average concentrations of Al, NO₃^-, non-sea-salt (nss)-SO₄^2-, and NH₄⁺ in aerosols were 2.19, 5.59, 6.16 and 2.08 ㎍ m^-3, respectively. The Al concentration in the high yellow dust period was about 100 times higher than that in the non-yellow dust period. The concentration ratio of NO₃^-/nss-SO₄^2- ranged between 0.47 and 1.5, indicating that the aerosols in the Cheju-Korea Straits are under the effects of NO_x and SO_x emitted from China, Korea and Japan. The equivalent concentration ratio of [NH₄⁺]/[nss-SO₄^2-+ NO₃^-] with the average of 0.58±0.29 indicates that nss-SO₄^2- and NO₃^- are not neutralized by NH₄⁺. A high activity concentration of ²¹⁰Pb with 1.13-1.23 mBq m^-3 was observed during the high yellow dust period, indicating that ²¹⁰Pb is easily adsorbed in the yellow dust originating from the continent of Asia. The distribution of ⁷Be and NH₄⁺ concentrations showed a strong negative linear correlation during the low yellow dust period, April 1998. The total mineral dust flux in the Cheju-Korea Straits was estimated to be 1.21×10⁶ tons yr^-1, accounting for about 12% of the annual sediment discharge via the Nakdong River. The combined annual deposition of NH₄⁺ and NO₃^- was 0.103 mole N m^-2 yr^-1 was estimated to support 4% of the annual primary productivity in the East China Sea.

• Journal of Korean Dental Hygiene Science
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• v.2 no.2
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• pp.31-39
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• 2019

Background: The purpose of this study was to investigate the effect of self-perception of halitosis on oral health behaviors of college students according to whether they worked in a non-service or service-related job. Methods: A self-reporting questionnaire of 150 university students working in service jobs and 150 university students working in non-service jobs in the metropolitan area was conducted from 26th April to 5th May 2018. The survey tool consisted of 3 general topic areas. There were 5 questions on oral health awareness behavior, 3 questions related to their self-perception of halitosis, and 8 questions on their oral health care practice. All were measured on the Likert 5-point scale. The frequency of their oral health behaviors and their self-perception of halitosis were analyzed according to the subjects' occupation. Pearson's correlation analysis and a linear regression analysis were conducted to confirm the influence of the two. The significance level for the statistical significance test was set to α = 0.05 (two-tailed). Results: In both the service and non-service groups, a coated tongue and food debris were found to influence halitosis(x²=10.95, p=0.027). According to the t-test, taking into account the self-perception of halitosis and oral health behaviors, both were higher in those that had a service job. Self-perception of halitosis and oral health behaviors were found to have a negative correlation(γ=-0.11, p<0.05). As the self-perception of halitosis increased, oral health care practices also increased(Beta=-0.185, p=0.020). Conclusions: Systematic interventions such as oral health programs and health promotion are needed to improve the oral health of service workers.

• Sleep Medicine and Psychophysiology
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• v.22 no.1
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• pp.11-19
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• 2015

Objectives: Whether daytime sleepiness is proportional to the severity of sleep apnea in obstructive sleep apnea syndrome (OSAS) is controversial. In this study we investigated how insomnia severity affects the association between daytime sleepiness and sleep apnea severity in OSAS. Methods: The present study included 235 male subjects who were diagnosed with OSAS based on clinical history and nocturnal polysomnography. Pearson's correlation analysis was conducted among sleep and mood-related self-reported data, polysomnographic data and demographic data of all subjects. Based on Pittsburgh Sleep Quality Index (PSQI), the subjects were divided into 2 groups; group A (n = 75; $PSQI{\leq}5$) and group B (n = 160; PSQI > 5). Partial correlation analysis was performed between the Epworth Sleepiness Scale (ESS) and other data in both groups. Multiple linear regression analysis was conducted to investigate the factors which affected the ESS in group A. Results: Pearson's correlation analysis showed weak or non-existent correlations between ESS and apnea severity data such as apnea-hypopnea index (AHI) (r = 0.148, p = 0.023), apnea index (AI) (r = 0.137, p = 0.036), hypopnea index (HI) (r = 0.058, p = 0.377), oxygen desaturation index (ODI) (r = 0.149, p = 0.022) and arousal total index (ATI) (r = 0.129, p = 0.048). Positive correlations between ESS and apnea severity data such as AHI ($r_p=0.313$, p = 0.008), AI ($r_p=0.339$, p = 0.004), ODI ($r_p=0.289$, p = 0.015) and ATI ($r_p=0.256$, p = 0.031) were observed only in group A. Multiple regression analysis showed that AI (t = 2.996, p = 0.004) and BAI (t = 2.721, p = 0.008) were associated with ESS in group A. Conclusion: The correlation between daytime sleepiness and sleep apnea severity was shown only in group A. This result suggests that associations between daytime sleepiness in OSAS and sleep apnea severity will become prominent when controlling for insomnia-related variables.

• Journal of Chest Surgery
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• v.41 no.1
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• pp.41-48
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• 2008

Background: Accurate assessment of the preload and the fluid responsiveness is of great importance for optimizing cardiac output, especially in those patients with coronary artery occlusive disease (CAOD). In this study, we evaluated the relationship between the parameters of preload with the changes in the stroke volume index (SVI) after fluid loading in patients who were undergoing coronary artery bypass grafting (CABG). The purpose of this study was to find the predictors of fluid responsiveness in order to assess the feasibility of using. certain parameters of preload as a guide to fluid therapy. Material and Method: We studied 96 patients who were undergoing CABG. After induction of anesthesia, the hemodynamic parameters were measured before (T1) and 10 min after volume replacement (T2) by an infusion of 6% hydroxyethyl starch 130/0.4 (10 mL/kg) over 20 min. Result: The right ventricular end-diastolic volume index (RVEDVI), as well as the central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP), failed to demonstrate significant correlation with the changes in the SVI (%). Only the right ventricular ejection fraction (RVEF) measured at T1 showed significant correlation. with the changes of the SVI by linear regression (r=0.272, p=0.017). However, when the area under the curve of receiver operating characteristics (ROC) was evaluated, none of the parameters were over 0.7. The volume-induced increase in the SVI was 10% or greater in 31 patients (responders) and under 10% in 65 patients (non-responders). None of the parameters of preload measured at T1 showed a significant difference between the responders and non-responders, except for the RVEF. Conclusion: The conventional parameters measured with a volumetric pulmonary artery catheter failed to predict the response of SVI following fluid administration in patients suffering with CAOD.

• Clinical and Experimental Pediatrics
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• v.50 no.6
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• pp.549-555
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• 2007

Purpose : Pulse wave velocity (PWV) and ankle brachial index (ABI) are simple, non-invasive methods to assess arterial stiffness. These parameters are also known to be closely related to cardiovascular risk factors and diseases. The purposes of this study were to measure blood pressure, PWV, ABI in healthy Korean adolescents, set up their normal values and assess their correlations. Methods : Three hundred ninety two healthy adolescents (213 boys and 179 girls) underwent measurement of brachial ankle pulse wave velocity (baPWV), ABI, body mass index(BMI) and blood pressure from four extremities. Linear regression analysis was performed to reveal the correlations between PWV, ABI and independent variables. Results : Blood pressure and PWV were significantly higher in all extremities in males compared to females. Blood pressure of both brachial and ankle showed positive correlation with body weight, height, and BMI, whereas ABI showed no correlation with any of these indices. Conclusion : Blood pressure increases as body weight, height and BMI increases. PWV shows positive correlation with blood pressure. It will be helpful to predict the risks of cardiovascular diseases in adolescents.