• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.270-275
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• 2006

The cultivated pearls collected for the study were pretreated through the removal of contaminants and the surface bleaching for easy dyeing. Coloring of pearls are necessary after selecting dyes adsorbable to the Conchiolin layer, a kind of hard protein formed in the seawater, covering the surface of the pretreated pearls. Dyes adsorbable to the Conchiolin layers are mostly basic dyes such as Rhodamine 6G(R6G), Rhodamine B(RB), Methylene Blue(MB) etc. and the binary and ternary competitive adsorption were performed by mixing two or three dyes together. The multi-dye adsorption data were compared with the predictions from the ideal adsorbed solution theory(IASI) combined with the single-dye adsorption model, the Langmuir or the Redlich-Peterson(RP) model. The quality of prediction was compared by using determination coefficient($R^2$) and standard deviation(SSE) values. Predictions from the IAST were found to be in good agreement with the data for the R6G/RB binary adsorption to the pearl layers not fractionated with their size, except for the adsorption data for RB at high concentrations. Among the three binary adsorption systems, R6G/RB, R6G/MB, and MB/RB, only the RB sorption data in the R6G/RB binary system was in poor agreement with the IAST prediction. Competitive adsorption data in ternay systems were in good agreement with the predictions from the IAST except for the RB data.

• Tuberculosis and Respiratory Diseases
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• v.83 no.3
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• pp.228-233
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• 2020

Background: The Bronchiectasis Health Questionnaire (BHQ) is a simple and repeatable, self-reporting health status questionnaire for bronchiectasis. We have translated the original version of the BHQ into Korean using a standardized methodology. The purpose of this study was to assess the validity of the Korean version of the BHQ (K-BHQ) with Korean patients. Methods: Stable state patients with bronchiectasis from two academic hospitals were enrolled in this study. The validity was assessed by investigating the relationship between the K-BHQ scores and the Korean version of the Chronic Obstructive Pulmonary Disease Assessment Test (K-CAT) scores. We also investigated the relationship between the K-BHQ scores and other variables of the modified Medical Research Council's (mMRC) dyspnea scale, lung function, and exacerbations. Results: A total of 126 patients with bronchiectasis were enrolled. The mean age was 64.3 (standard deviation [SD], 9.7). Women comprised 53.2% of the patients. The mean forced expiratory volume in one second (FEV₁) was 60% of the predicted value (SD, 18.9%); the mean K-CAT score was 17.6 (SD, 9.1). The K-BHQ scores correlated strongly with the K-CAT scores (r=-0.656, p<0.001). There was significant correlation between the K-BHQ scores and the mMRC dyspnea scale (ρ=-0.409, p<0.001), FEV₁ (r=0.406, p<0.001), and number of exacerbations requiring hospitalization (ρ=-0.303, p=0.001). Conclusion: The K-BHQ is valid for assessing the health-related quality of life or health status of Korean bronchiectasis patients.

• Journal of the Korean Geotechnical Society
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• v.36 no.3
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• pp.15-23
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• 2020

Ground motion models predicting intensity measures on surface use a time-averaged shear wave velocity, V_S30, as a key variable simulating site effect. The V_S30 can be directly estimated from V_S profiles if the profile depth (z) is greater than or equal to 30 m. However, some sites have V_S profiles with z < 30 m. In this case V_S30 can be predicted using extension models. This study proposes new coefficient sets for existing prediction equations using 297 Korea V_S profiles. We have collected V_S profiles from KMA and Geoinfo database. Fitting six existing methods to data, we suggest new coefficients for each method and evaluate their performance. It turns out that if z ≥ 15 m, the standard deviation (σ) of residual in log₁₀ is 0.061, which indicates that the estimated V_S30 is nearly accurate. If z < 15 m, the σ keeps increasing up to 0.1 for z = 5 m, so we caution the use of models at very low z. Nonetheless, we recommend investigating up to 30 m depth for V_S30 calculation if possible.

• Horticultural Science & Technology
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• v.33 no.5
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• pp.712-721
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• 2015

To improve the breeding efficiency of oriental pear, heritability, correlation and frequency distribution of fruit ripening date were analyzed using 4,035 seedlings obtained from 15 families between 13 parental cultivars. Although variation of fruit ripening time was higher in most early-ripening parental cultivars than in late-ripening parental cultivars, according to analysis of average, standard deviation, and coefficient of ripening variation for ten years, fruit ripening time obtained from all parental cultivars was inherited narrower and more stable variation than others fruit trait, with 0.92-3.41 in coefficient of variation. The heritability of fruit ripening time was calculated to be over 0.8 in almost all crosses and average fruit ripening time of seedlings from cross combinations could be predicted based on that of the parental cultivars due to its superior heritability relative to other fruit traits. The average ripening time was earlier than the mid-parental value in families obtained from cross combinations using at least one late-ripening cultivar as parent, indicating that the early-ripening trait was more likely to be dominant compared to the late-ripening trait. By contrast, average ripening time was clustered in families of crosses not only between mid-season and early-season cultivars, but also between mid-season and mid-season cultivars. There was highly significant relationship (at 0.68) between mid-parental and progeny mean fruit ripening time. The correlation between fruit ripening time and fruit weight was also highly positive and thus, the mid-parental fruit ripening time could be a potent criterion for indirect selection of fruit weight.

• Journal of Energy Engineering
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• v.15 no.4 s.48
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• pp.243-249
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• 2006

An experimental study on the refrigerant-side pressure drop of slit fin an tube heat exchanger has been carried out. A comparison was made between the predictions of previously proposed empirical correlations and experimental data for the pressure drop on design conditions of condenser in micro-fin tube for R22 and Rl34a. Experiments were carried out under the conditions of inlet refrigerant temperature of $60^{\circ}C$ and mass fluxes varying from $150\;to\;250\;kg/m^{2}s$ for R22 and Rl34a. The inlet air conditions are dry bulb temperature of $35^{\circ}C$, relative humidity of 40% and air velocity varying from 0.68 to 1.43 m/s. Experiments show that pressure drop for R134a was $22{\sim}22.6%$ higher than R22 for the degree of subcooling $5^{\circ}C$ For the mass fluxes of $200{\sim}250\;kg/m^{2}s$, the deviation between the experimental and predicted values for the pressure drop was less than ${\pm}20%$ for R22 and Rl34a.

• The Journal of the Korea Contents Association
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• v.15 no.1
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• pp.366-378
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• 2015

The purpose of this study conducted in the United States was to identify the level of role stressors among professions at centers for independent living and to investigate the relationship between role stressors and burnout at the target population. A total of 218 professions completed a web-based and hard copy survey. The participants reported a mean (standard deviation) score of 22.48 (5.80) for the role conflict dimension, 22.20 (4.30) for the role ambiguity dimension, and 9.14 (2.55) for the role overload. Demographic assessment of the differences on the mean score of the three role stressors revealed significant associations with that age, job title, highest level of education, years of human service experience and working hours per week for role conflict/role ambiguity, and experience in human service for role overload. The role conflict, ambiguity, and overload stressors were significant predictors of emotional exhaustion and depersonalization explaining 26% and 14% of the variance, respectively. None of the stressors significant predicted personal accomplishment. The results indicate that role conflict, ambiguity, and overload are important predictors of burnout among professions at centers for independent living.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.903-911
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• 2022

Groundwater, one of the resources for supplying water, fluctuates in water level due to various natural factors. Recently, research has been conducted to predict fluctuations in groundwater levels using Artificial Neural Network (ANN). Previously, among operators in ANN, Gradient Descent (GD)-based Optimizers were used as Optimizer that affect learning. GD-based Optimizers have disadvantages of initial correlation dependence and absence of solution comparison and storage structure. This study developed Gradient Descent combined with Harmony Search (GDHS), a new Optimizer that combined GD and Harmony Search (HS) to improve the shortcomings of GD-based Optimizers. To evaluate the performance of GDHS, groundwater level at Icheon Yullhyeon observation station were learned and predicted using Multi Layer Perceptron (MLP). Mean Squared Error (MSE) and Mean Absolute Error (MAE) were used to compare the performance of MLP using GD and GDHS. Comparing the learning results, GDHS had lower maximum, minimum, average and Standard Deviation (SD) of MSE than GD. Comparing the prediction results, GDHS was evaluated to have a lower error in all of the evaluation index than GD.

• Journal of Environmental Health Sciences
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• v.49 no.2
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• pp.89-98
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• 2023

Background: Organophosphorus flame retardants (OPFRs) are a group of chemical substances used in building materials and plastic products to suppress or mitigate the combustion of materials. Although OPFRs are generally used in mixed form, information on their mixture toxicity is quite scarce. Objectives: This study aims to elucidate the toxicity and determine the types of interaction (e.g., synergistic, additive, and antagonistic effect) of OPFRs mixtures. Methods: Nine organophosphorus flame retardants, including TEHP (tris(2-ethylhexyl) phosphate) and TDCPP (tris(1,3-dichloro-2-propyl) phosphate), were selected based on indoor dust measurement data in South Korea. Nine OPFRs were exposed to the luminescent bacteria Aliivibrio fischeri for 30 minutes and the human hepatocyte cell line HepG2 for 48 hours. Chemicals with significant toxicity were only used for mixture toxicity tests in HepG2. In addition, the observed EC_x values were compared with the predicted toxicity values in the CA (concentration addition) prediction model, and the MDR (model deviation ratio) was calculated to determine the type of interaction. Results: Only four chemicals showed significant toxicity in the luminescent bacteria assays. However, EC₅₀ values were derived for seven out of nine OPFRs in the HepG2 assays. In the HepG2 assays, the highest to lowest EC₅₀ were in the order of the molecular weight of the target chemicals. In the further mixture tests, most binary mixtures show additive interactions except for the two combinations that have TPhP (triphenyl phosphate), i.e., TPhP and TDCPP, and TPhP and TBOEP (tris(2-butoxyethyl) phosphate). Conclusions: Our data shows OPFR mixtures usually have additivity; however, more research is needed to find out the reason for the synergistic effect of TPhP. Also, the mixture experimental dataset can be used as a training and validation set for developing the mixture toxicity prediction model as a further step.

• 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.

• Clinical and Experimental Pediatrics
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• v.48 no.8
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• pp.865-870
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• 2005

Purpose : The use of growth hormone(GH) to promote growth in normal short children without classical GH deficiency is controversial. Numerous foreign studies have shown the effects of GH therapy in children with idiopathic short stature(ISS) whereas few has been interested in Korea. Therefore, this study is designed to investigate the effects of GH therapy on ISS by observing correlations and changes among various growth parameters such as, insulin-like growth factor-I(IGF-I) and insulin-like growth factor binding protein-3(IGFBP-3). Methods : This study was conducted retrospectively with 15 children with ISS in Chungbuk National University Hospital in Korea. Mean age was $11.44{\pm}2.81$ and the children were treated with 0.66 IU/kg/wk dosage of GH for 1 or 2 years. Also, the growth parameters before and after the GH therapy were observed. Results : Height standard deviation score(HT-SDS) was increased from $-1.85{\pm}0.70$ to $-1.58{\pm}0.56$ at 1 year and to $-1.21{\pm}0.37$ at 2 years after GH therapy. Predicted adult height standard deviation score(PAH-SDS) was also increased from $-2.10{\pm}0.52$ to $-1.67{\pm}0.59$ at 1 year, and to $-0.96{\pm}0.60$ at 2 years. Serum IGF-I and IGFBP-3 levels were significantly increased after 1 year and marginally increased after 2 years of GH therapy. Conclusion : It is concluded that GH therapy has growth promoting effect. The significant increase in IGF-I and IGFBP-3 levels during the GH therapy suggests that IGF-I and IGFBP-3 are useful predictors of response to the use of GH therapy. It is expected that larger patient samples would provide more reliable information about the effect of GH therapy.