• Journal of Food Hygiene and Safety
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• v.34 no.5
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• pp.431-437
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• 2019

This study was conducted to develop a simultaneous analysis method for ferulic acid, caffeic acid, catechin and taxifolin from Health Functional Food (HFF) Pinus Pinaster bark extract. The simultaneous analytical method for ferulic acid, caffeic acid, catechin and taxifolin is carried out using UPLC-MS/MS. The method validation was performed to determine selectivity, linearity, accuracy, limit of detection (LOD), limit of quantification (LOQ) and precision for ferulic acid, caffeic acid, catechin and taxifolin. LC-MS/MS method was established using an Acquity UPLC BEH $C_{18}$ Column and was applied for these 4 compounds. Product-ion traces, at m/z $194.2{\rightarrow}133$, $180.2{\rightarrow}135$, $290.3{\rightarrow}245$, $304.3{\rightarrow}248$, were used for quantitative analysis of ferulic acid, caffeic acid, catechin and taxifolin, respectively. Excellent linearity ($r^2=0.999$) was observed for ferulic acid, caffeic acid, catechin and taxifolin in the concentration range (50-2500 mg/L). The observed recoveries of these 4 compounds were found to be between 84.9 and 104.9%, while precision was between 1.20 and 4.43% relative standard deviation (% RSD).

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.417-424
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• 2021

Algal bloom is an ongoing issue in the management of freshwater systems for drinking water supply, and the chlorophyll-a concentration is commonly used to represent the status of algal bloom. Thus, the prediction of chlorophyll-a concentration is essential for the proper management of water quality. However, the chlorophyll-a concentration is affected by various water quality and environmental factors, so the prediction of its concentration is not an easy task. In recent years, many advanced machine learning algorithms have increasingly been used for the development of surrogate models to prediction the chlorophyll-a concentration in freshwater systems such as rivers or reservoirs. This study used a light gradient boosting machine(LightGBM), a gradient boosting decision tree algorithm, to develop an ensemble machine learning model to predict chlorophyll-a concentration. The field water quality data observed at Daecheong Lake, obtained from the real-time water information system in Korea, were used for the development of the model. The data include temperature, pH, electric conductivity, dissolved oxygen, total organic carbon, total nitrogen, total phosphorus, and chlorophyll-a. First, a LightGBM model was developed to predict the chlorophyll-a concentration by using the other seven items as independent input variables. Second, the time-lagged values of all the input variables were added as input variables to understand the effect of time lag of input variables on model performance. The time lag (i) ranges from 1 to 50 days. The model performance was evaluated using three indices, root mean squared error-observation standard deviation ration (RSR), Nash-Sutcliffe coefficient of efficiency (NSE) and mean absolute error (MAE). The model showed the best performance by adding a dataset with a one-day time lag (i=1) where RSR, NSE, and MAE were 0.359, 0.871 and 1.510, respectively. The improvement of model performance was observed when a dataset with a time lag up of about 15 days (i=15) was added.

• Clean Technology
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• v.25 no.2
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• pp.140-146
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• 2019

Flammable substances, such as organic solvents, are commonly used in laboratories and industrial processes. The flash point of flammable liquid mixtures is a very important parameter for characterizing the ignition and explosion hazards, and the flash points of mixtures of $C_2{\sim}C_3$ alcohols and 2,2,4-trimethylpentane were measured in the present study. The 2,2,4-trimethylpentane is an important component of gasoline and is frequently used in the petroleum industry as a solvent. Lower flash point data were measured for the binary systems {ethanol + 2,2,4-trimethylpentane}, {1-propanol + 2,2,4-trimethylpentane}, and {2-propanol + 2,2,4-trimethylpentane}. The flash point measurements were carried out according to the standard test method (ASTM D3278) using a Stanhope-Seta closed cup flash point tester. The measured flash points were compared with the predicted values calculated using Raoult's law and also following $G^E$ models: Wilson, Non-Random Two Liquid (NRTL) and UNIversal QUAsiChemical (UNIQUAC). These models were able to predict the experimental flash points for different compositions of {$C_2{\sim}C_3$ alcohols + 2,2,4-trimethylpentane} mixtures with minimal deviations. The average absolute deviation between the predicted and measured lower flash point was less than 1.28 K. A minimum flash point behaviour was observed in all of the systems as in the many observed cases for the hydrocarbon and alcohol mixtures.

• Annals of Pediatric Endocrinology and Metabolism
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• v.23 no.4
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• pp.210-214
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• 2018

Purpose: Premature adrenarche (PA) often leads to polycystic ovary syndrome (PCOS). Higher anti-mullerian hormone (AMH) levels are reported in PCOS. We studied the androgen profile and AMH profiles in Hispanic girls with PA (aged 5-8 years) and age and body mass index (BMI) matched controls. Methods: Retrospective review of electronic medical records of girls who met the inclusion criteria for premature adrenarche were done. Results: PA girls (n=76) were matched to control girls (n=12) for age (mean${\pm}$standard deviation) ($6.7{\pm}1years$ vs. $6.2{\pm}1.3years$) and BMI ($20{\pm}10kg/m^2$ vs. $17.8{\pm}2.7kg/m^2$). Dehydroepiandrostenedione sulfate ($63.3{\pm}51.3{\mu}g/dL$ vs. $29.8{\pm}17.3{\mu}g/dL$, P<0.001) and testosterone levels ($11.4{\pm}4.8ng/dL$ vs. $8.2{\pm}2.9ng/dL$, P=0.001) were significantly higher in the PA group than controls. AMH values (<14 years: reference range, 0.49-3.15 ng/mL) were $3.2{\pm}2.2ng/mL$ vs. $4.6{\pm}3.2ng/mL$ respectively in the PA and control groups and were not different (P=0.4). AMH did not show a correlation with bone age (P=0.1), and testosterone (P=0.9) in the PA group. 17-hydroxyprogesterone levels (17-OHP ng/dL) were $39.5{\pm}30.5ng/dL$ vs. $36.8{\pm}19.8ng/dL$ in PA versus control girls. The concentration of 17-OHP was not statistically different between the control and PA groups. Conclusion: Higher AMH was not observed in PA girls and no correlation with BA and androgen levels was observed.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.5
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• pp.449-463
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• 1990

To obtain the basic informations on quality improvement, seed protein and amino acid composition were analyzed in 460 strains of perilla germplasm. Among the tested strains, total protein content ranged from 17.9% to 28.1 % with the 23.6% of varietal means. Form the experiment, Namji, Sandong, and Eunjin were selected as high protein strains of which content was as high as 28.1%. In protein content, collected strains from Jeonnam province showed highest, and was not significantly different by maturity, but this characteristics showed differences by seed coat color and 1,000 seed weight. The significantly negative correlation was observed between protein content and seed setting ratio. However it was observed that significant and high positive correlation between protein and oil content. A calibration for an Infra-Alyzer 450 using log reflectance readings at 2208, 1982, 1940 and 1722nm could be used without adjustment for the measurment of the protein content in perilla with a standard deviation of differences against micro-kjeldahl of 0.27%. The amino acid composition of perilla was similar to the other oilseed crops, and showed a relatively high lysine and methionine content. Further, amino acid composition of perilla seed was exellently characterized with bal ance and higher than FAO recommendation. Major amino acids were indentified as a glutamic acid and arginine in perilla seed protein.

• Analytical Science and Technology
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• v.36 no.3
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• pp.105-112
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• 2023

Lycopene, a carotenoid hydrocarbon is known to have effects on reducing cardiovascular risk factors, blood lipids, and blood pressure. Thus, a lot of supplementary foods with lycopene in several dosage forms like soft capsule filled with liquid and hard capsule filled with powder are available in a market. Recently, however, our research group found that the lycopene assay in Supplementary Food Code of South Korea is only valid for oily lycopene preparation. Thus, here, we developed a simple method to determine lycopene in solid preparations for Supplementary Food Code of South Korea using saponification and liquid chromatography with an absorbance detector. The method was validated following Ministry of Food and Drug Safety guidelines. All validation parameters observed in this study were within acceptable criteria of the guidelines (selectivity, linearity of r² ≥ 0.991, lower limit of quantification of 0.0149 mg/mL, accuracy as recovery (R) between 92.70 and 97.18 %, repeatability as relative standard deviation (RSD) values of R between 0.85 and 1.59 %, and reproducibility as the RSD value of interlaboratory R of 3.70 %). Additionally, the practical sample applicability of the validated method was confirmed by accuracy between 98.81 and 101.59 % observed from its lycopene certified reference material (CRM) analyses. Therefore, the present method could contribute to fortify the supplementary food safety management system in South Korea.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.4
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• pp.83-93
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• 2023

Purpose : This study examined the effects of college students' occupational value and social support on their career decision status. Methods : This research was conducted between May 6 and May 30 in 2023 with 228 college students from city B in South Korea as the study participants. The frequency, percentage, mean, and standard deviation of the collected data were analyzed, while t-test, ANOVA test, Scheffe's test, Pearson correlation coefficient, and a multivariate regression analysis were conducted using the SPSS/WIN 22.0 program. Results : The analysis revealed that the research subjects had an average occupational value of 3.58±.44, social support of 4.18±.56, and a career decision status of 2.82±.59. Notably, a significant difference in the career decision status of the students was observed with regard to their fields of major (F=2.36, p=.019), However, no other variable demonstrated a significant difference. The confidence level pertaining to career decision-making was found to be positively correlated with the pursuit of status and self-direction (r=.25, p<.001), pursuit of creativity (r=.16, p=.017), pursuit of relationship (r=.35, p<.001), pursuit of diversity and change (r=.16, p=17), pursuit of interest (r=.19, p=.003), pursuit of compensation (r=.29, p<.001), pursuit of professionalism (r=.46, p<.001), material support (r=.25, p<.001), appraisal support (r=.35, p<.001), informational support (r=.32, p<.001), and emotional support (r=.29, p<.001). Moreover, the indecision level related to career decision-making demonstrated a positive correlation with the pursuit of excellence (r=.17, p=.010). The factors that affected the confidence level of career decision-making included appraisal support (β=.29, p<.001) and pursuit of compensation (β=.19, p=.003), whose collective explanatory power was 15 %. It was further observed that appraisal support (β=-.27, p<.001), pursuit of professionalism (β=-.16 p=.017), pursuit of excellence (β=.17, p=.005), and the field of major (β=-.16, p=.012) largely influenced the indecision level related to career decision-making, together bearing an explanatory power of 17 %. Conclusion : The results of this study have important implications for enhancing college students' career decision status. Moreover, further research investigating the diverse variables that affect students' career decision status is necessary, along with effective endeavors to improve education and develop programs that positively affect college students' career decision status.

• Korean Journal of Radiology
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• v.22 no.10
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• pp.1609-1618
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• 2021

Objective: Arrhythmogenic mitral valve prolapse (MVP) is an important cause of sudden cardiac death characterized by fibrosis of the papillary muscles or left ventricle (LV) wall, and an association between late gadolinium enhancement (LGE) of the LV papillary muscles and ventricular arrhythmia in MVP has been reported. However, LGE of the papillary muscles may be observed in other causes of mitral regurgitation, and it is not limited to patients with MVP. This study was to evaluate the association of LGE of the LV papillary muscles or ventricular wall on cardiac magnetic resonance imaging (CMR) and ventricular arrhythmia in patients with mitral regurgitation. Materials and Methods: This study included 88 patients (mean age ± standard deviation, 58.3 ± 12.0 years; male, 42%) with mitral regurgitation who underwent CMR. They were allocated to the MVP (n = 43) and non-MVP (n = 45) groups, and their LGE images on CMR, clinical characteristics, echocardiographic findings, and presence of arrhythmia were compared. Results: LV myocardial wall enhancement was more frequent in the MVP group than in the non-MVP group (28% vs. 11%, p = 0.046). Papillary muscle enhancement was observed in 7 (7.9%) patients. Of the 43 patients with MVP, 15 (34.8%) showed LGE in the papillary muscles or LV myocardium, including 12 (27.9%) with LV myocardial wall enhancement and 4 (9.3%) with papillary muscle enhancement. One patient with bilateral diffuse papillary muscle enhancement experienced sudden cardiac arrest due to ventricular fibrillation. Univariable logistic regression analysis showed that high systolic blood pressure (BP; odds ratio [OR], 1.05; 95% confidence interval [CI], 1.01-1.09; p = 0.027) and ventricular arrhythmia (OR, 6.84; 95% CI, 1.29-36.19; p = 0.024) were significantly associated with LGE of the papillary muscles. Conclusion: LGE of the papillary muscles was present not only in patients with MVP, but also in patients with other etiologies of mitral regurgitation, and it was associated with high systolic BP and ventricular arrhythmia. Papillary muscle enhancement on CMR should not be overlooked.

• Journal of the Korean Orthopaedic Association
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• v.54 no.3
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• pp.261-268
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• 2019

Purpose: The authors measured the anteversion of the femoral neck and acetabulum and the sum of the two values in normal Korean people by computed tomography. The authors examined the normal range of the values to analyze the difference in sex and sides as well as the relationship between the femoral neck and acetabular anteversion. Materials and Methods: The authors measured the anteversion of the femoral neck and acetabulum in 118 normal Korean adult males and 114 females aged between 21 and 49 on both the right and left sides by computed tomography and calculated the sum of anteversion. The authors analyzed the mean and standard deviation, and investigated the sex differences and side differences, as well as the relationship between the acetabular anteversion and femoral neck anteversion statistically. Results: The anteversion of the acetabulum in males was 15.3°±6.1° on the right side and 15.3°±6.6° on the left side. The anteversion of the femoral neck in males was 5.3°±7.6° on the right side and 1.5°±9.2° on the left side according to the Hernandez et al. method. The anteversion of acetabulum in females was 16.8°±5.4° on the right side and 16.3°±5.8° on the left side. The anteversion of femoral neck in females was 10.3°±8.2° on the right side and 7.9°±8.2° on the left side according to Hernandez et al. method. No difference in acetabular anteversion, and a significant difference in the femoral neck anteversion on both the right and left sides were observed between males and females. No difference of acetabular anteversion was observed between the right and left sides, but a significant difference in femoral neck anteversion was noted between the right and left sides measured by either the Hernandez et al. method or Weiner et al. method. The Pearson coefficient revealed no correlation between the femoral neck anteversion and acetabular anteversion. Conclusion: No difference in the acetabular anteversion was observed, but there was a significant difference in femoral neck anteversion between males and females. A significant difference in femoral neck anteversion was observed between the right and left sides. No correlation was noted between the anteversion of the femoral neck and acetabulum.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.1
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• pp.1-14
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• 1978

To study the fluctuation of cold water in the East China Sea in summer heat budget of the Yellow Sea in winter was analysed based on the oceanographic and meteorological data compiled from 1951 to 1974. The maintain value of insolation was observed in December($160{\sim}190ly/day$), while the maximum in February ($250{\sim}260ly/day$). The range of the annual variation was found to be less than 50 ly/day. The value of the radiation term ($Q_s-Q_r-Q_h$) was remarkably small (mean 20 ly/day) in winter. It was negative value in December and January, and a positive value in February. The minimum total heat exchange from the sea ($Q_({h+c}$) was found value (471 ly/day) in February 1962, and the maximum (882 ly/day) in January 1963. The annual total heat exchange was minimum (588 ly/day) in 1962, and maximum (716 ly/day) in 1968. If the average deviation of mean water temperature at 50m depth layer were assumed to be the horizontal index ($C_h$) of colder water, $C_h$ is $C_h=\frac{{\Sigma}\limit_i\;A_i\;T_i}{{\Sigma}\limit_i\;A_i}$ where $A_i$ denotes the area of isothermal region and $T_i$ the value of deviation from mean sea water temperature. The vertical index ($C_v$) of cold water can be expressed similarly. Consequently the total index (C) of cold water equals to the sum of the two components, i.e. $C=C_h$＋$C_v$. Taking the deviation of mean sea surface temperature(T'w) in the third ten-day of Novembers in the Yellow Sea as the value of the initial condition, the following expressions are deduced : $C－T'w＝32.06 - 0.049$ $\;Q_T$ $C_h-T'w/2=12.20-0.019\;Q_T$ $C_v-T'w/2＝18.07-0.027\;Q_T$ where $Q_T$ denotes the total heat exchange of the sea. The correlation coefficients of these regression equations were found to be greater than 0.9. Heat budget was 588 ly/day in winter, and minimum water temperature of cold water was $18^{\circ}C$ in summer of 1962. The isotherm of $23^{\circ}C$ extended narrowly to southward up to $29^{\circ}N$ in summer. However, heat budget was 716 ly/day, and minimum water temperature of cold water was $12^{\circ}C$ in summer of 1968. The isotherm of $23^{\circ}C$ extended widely to southward up to $28^{\circ}30'N$ in summer. As a result of the present study, it may be concluded that the fluctuation of cold water of the East China Sea in summer can be predicted by the calculation of heat budget of the Yellow Sea in winter.