• Communications for Statistical Applications and Methods
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• v.31 no.4
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• pp.409-425
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• 2024

Logistic regression models are commonly used to explain binary health outcome variable using independent variables such as patient characteristics in medical science and public health research. Although there is no distributional assumption required for independent variables in logistic regression, variables with severely right-skewed distribution such as lab values are often log-transformed to achieve symmetry or approximate normality. However, lab values often have zeros due to limit of detection which makes it impossible to apply log-transformation. Therefore, preprocessing to handle zeros in the observation before log-transformation is necessary. In this study, five methods that remove zeros (shift by 1, shift by half of the smallest nonzero, shift by square root of the smallest nonzero, replace zeros with half of the smallest nonzero, replace zeros with the square root of the smallest nonzero) are investigated in logistic regression setting. To evaluate performances of these methods, we performed a simulation study based on randomly generated data from log-normal distribution and logistic regression model. Shift by 1 method has the worst performance, and overall shift by half of the smallest nonzero method, replace zeros with half of the smallest nonzero method, and replace zeros with the square root of the smallest nonzero method showed comparable and stable performances.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.2
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• pp.117-132
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• 1998

The main purposes of this study are to investigate the distributional characteristics of polycyclic aromatic hydrocarbons (PAH) in the vapor and particulate phases in the ambient atmosphere, and to evaluate the effect of ambient temperature on the vapor-particle partitioning during the sampling period. A total of 64 samples were collected during a period of 1995 to 1996, using a medium-volume sampler with XAD-2 adsorbents and quartz fiber filters. Analyses of PAH were carried out using HPLC with UV and Fluorescence detections. In this study, a significant seasonal variation in the distributions was observed, reflecting the effect of ambient temperature on the vapor-particle partitioning of PAH. The relationship between the vapor-particle distributions of the 3 to 5 rings PAH and ambient temperature is considered to be well described using the Langmuir adsorption concept. The estimated empirical constants for each PAH in the relationship, particularly for the more volatile compounds, were also comparable with results from other studies. However, it is still difficult to accurately estimate the initial vapor-particle distribution of PAH in the ambient air, since it is not known to what extent the trapped vapours originated from the particles laden in the filter by being volatilized or from the air samples initially present in the vapour phase. The distribution factors for volatile PAH with 3 to 4 rings appeared to be comparable with those in the literature. It should be noted, however, that these distribution factors give information only about the distribution of PAH between the two phases under a specific sampling condition, and hence may provide only semi -quantitative information on the vapor-particle distributions in the atmosphere.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.98-104
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• 2008

This research was performed to evaluate the extraction characteristics of heavy metals for soil washing of mine tailings-contaminated soil according to particle size distribution and the chemical distributional existence of the metals. As the soil particle size was decreased, the extracted concentrations of heavy metals was increased except Fe and Mn. Most of all heavy metals were extracted within 6 h by soil washing with 0.05 M EDTA. Extraction efficiency of metals was decreased for Pb, Cu, and Zn with decreasing of particle size. Significant difference was not observed in extraction efficiency for Cd according to particle size distribution. Extraction efficiency for Cd was the highest as 86~91%, while the lowest as 5~14% for Fe. Most metals of the soil without soil washing was distributed as reducible, oxidizable, and residual fractions. Pb, Zn, and Cd existed as reducible (Fe/Mn oxide) and residual fractions and Cu existed as oxidizable and residual fractions after soil washing treatment with 0.05 M EDTA. As the soil particle size was decreased, residual fraction was increased for Pb and Cu. About 90% of reducible fraction in Pb, Zn, and Cd was removed by soil washing with 0.05 M EDTA. As the results, it was founded that soil particle size was the important parameter to effect on distributional fraction and extraction efficiency of metals in mine tailings-contaminated soil.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.7
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• pp.1-11
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• 2020

This study investigated the mesozooplankton community and the related environmental factors in the Nakdong River Estuary in May and early October shortly after passage of the typhoon "DUJUAN" in 2015. The mesozooplankton community was dominated by barnacle nauplii, foraminiferans, and Noctiluca scintillans, and the environmental characteristics were characterized by freshwater inflow through the Nakdong River barrage, the intrusion of warm currents, and the effect of typhoon passage in October. In May, cladocerans, such as Evadne nordmanni and Podon polyphemoides, as indicator species of brackish water, prevailed throughout the study area. The surface salinity was lowest on the inner side of the barrier-islands and increased gradually to the outer side during the study. The average concentration of total suspended solids in October was higher than that in May, while the averaged concentration of nitrate and chlorophyll-a in May was higher than those in October. On the other hand, there was no temporal difference in the total averaged abundance of mesozooplankton. In contrast, the distributional pattern of the mesozooplankton community was associated with the salinity gradient in both seasons. These results suggest that the temporal difference of the mesozooplankton community depended on the extent of freshwater inflow by barrage opening, the intrusion intensity of warm currents, and typhoon passage in the Nakdong River estuary in 2015.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.6
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• pp.775-784
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• 2023

In terms of flood management, it is necessary to analyze quantitative rainfall and runoff from a spatial and temporal perspective and to analyze runoff for heavy rainfall events that are concentrated within a short period of time. The simulation and analysis results of rainfall-runoff models vary depending on the type and input data. In particular, rainfall data is an important factor, so calculating areal mean rainfall is very important. In this study, the areal mean rainfall of the Samcheok Osipcheon(Riv.) watersheds located in the mountainous terrain was calculated using the Arithmetic Mean Method, Thiessen's Weighting Method, and the Isohyetal Method, and the rainfall-runoff results were compared by applying the distributional model S-RAT and the lumped model HEC-HMS. The results of the temporal transferability study showed that the combination of the distributional model and the Isohyetal Method had the best statistical performance with MAE of 64.62 m³/s, RMSE of 82.47 m³/s, and R² and NSE of 0.9383 and 0.8547, respectively. It is considered that this study was properly analyzed because the peak flood volume occurrence time of the observed and simulated flows is within 1 hour. Therefore, the results of this study can be used for frequency analysis in the future, which can be used to improve the accuracy of simulating peak flood volume and peak flood occurrence time in mountainous watersheds with steep slopes.

• Archives of Craniofacial Surgery
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• v.19 no.3
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• pp.190-193
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• 2018

Background: This study was conducted to determine the effect of the distributional relationship between dental roots and the mandibular bone on single mandibular bone fractures, which are common craniofacial fractures. Methods: This was a retrospective, single-center study in Seoul, Korea. Patients with single mandibular fractures in the symphysis, parasymphysis, body, and angle area, with tooth structure involvement were included. The control group included patients with simple, bone-level lacerations without fractures. In total, 94 patients (72 males and 22 females) were included in the treatment group, and 125 (71 males and 54 females) were included in the control group. The height of the mandibular bone and the dental root were measured with panoramic radiography. The central incisor represented the symphysis area, the canine represented the parasymphysis area, the first molar represented the body area, and the second molar represented the angle area. Results: In the treatment group, symphysis fractures occurred in 16 patients (17%), parasymphysis fractures in 36 patients (38%), body fractures in 17 patients (18%), and angle fractures in 25 patients (27%). The ratios of the dental roots to the total height of the mandibular bone in the treatment group were 30.35%, 39.75%, 39.53%, and 36.27% for symphysis, parasymphysis, body, and angle areas, respectively, whereas in the control group, they were 27.73%, 39.70%, 36.76%, and 35.48%. The ratios of the treatment group were significantly higher than those of the control group. Conclusion: The results show that the higher ratio of the dental root to the height of the mandibular bone increases the fracture risk.

• Culinary science and hospitality research
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• v.17 no.3
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• pp.65-75
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• 2011

The purpose of the study was to explore the relationship between satisfaction and future behavior intention of cafeteria users. Respondents of the research were cafeteria users in major colleges in Kyunggi province. A total of 300 questionnaires were distributed between October 1, 2010 and October 20, 2010 but only281 questionnaires were used for the analysis. Based on 14 selection attributes, factor analysis showed that the KMO value of 0.634, which was extracted by Verimax vertical rotation, and=610.084(p<0.001). In addition, the distributional explanation showed a total of 61.685%. Five factors were obtained as ingredients, food, menu, maintenance, and internal environment factors according to the feature of each variable. The Cronbach value according to confidence and validity tests was 0.703. The explanation was 16.3% and the influence on satisfaction included ingredients, maintenance, and internal environment. The effect on future behavior intention was significant at the level of p<0.001. This study has limitations in that it has generalized the findingson consumers of university cafeterias; therefore, follow-up studies must be conducted.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.111-119
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• 1976

Discoloration of canned boiled oyster namely greening, yellowing and browning often occur separately or associatively in the storage of the product. Greening is mainly caused by the appearance of chlorophyll and its derivatives on the surface around the digestive diverticula of the oyster and yellowing by dispersion of carotenoid. Browning reactions by sugar amino condensation or enzymatic action, tyrosinase, also cause an undesirable color development. In this paper, the stability and the changes in distributional or partitional ratio of chlorophyll and carotenoid pigment of meat vs viscera in raw and canned oyster during six month storage in order to measure the dispersion rate of both pigments between meat and viscera, and to evaluate the feasibility of discoloration of oyster meat. The development of brownish pigment and the toss of free tyrosine in oyster were also determined to compare the readiness of color development. In addition the influence of processing and storage conditions to the dispersion rate and the tendency of discoloration, and finally the effect of inhibitor were discussed. The results showed that greening or yellowing was initiated by the dispersion of chlorophyll or carotenoids from viscera to the meat of oyster, and the dispersion rate of carotenoid was much higher than the chlorophyll's, so that, yellowing appeared a leading reaction of discoloration. The dispersion rate was obviously fastened by raising the temperature in the process of sterilization and storage. Consequently, the low temperature storage could largely retard the occurance of yellowing or greening of oyster meat. The pH control of canned oyster did not seem to affect the dispersion of pigment but significantly did on the stability of the piqments. Browning by the reaction of sugar-amino condensation and enzymatic oxidation of tyrosine was positively detected in canned oyster meat. The development of brownish color was influenced rather by the storage temperature than the heating process. Addition of sodium sulfite in can or treating the boiled oyster with sulfite solution prior to filling seemed possibly inhibit the color development particularly in cold-storaged oyster meat.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.6
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• pp.1568-1572
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• 2005

Polycyclic aromatic hydrocarbon (PAH), such as benzo(a)pyrene (B(a)P), are toxic environmental contaminants known to enhance oxidative stress, production of pro-inflammatory and inflammatory cytokines. The present study was designed in order to determine whether wild ginseng (Panax ginseng C. A. Meyer) protect PAH-induced oxidative stress and inflammation. B(a)P (0.5 mg/kg, i.p.) treatment increased the distribution of immunoreactive cells for tumor necrosis factor $(TNF)-\alpha$ and cyclooxygenase (COX)-2 in peri-portal triad region and immunoreaction was shown in the cytoplasm of macrophage. Pre-treatment with wild ginseng significantly decreased immune responses in the rats treated with B(a)p. The rats given 50 mg/kg/day for 4 weeks before B(a)P treatment had 1.39-fold and 1.5-fold inhibition of $TNF-\alpha$ and COX-2 positive reaction, respectively. Wild ginseng extract alone had no effect on the distributional changes. The SOD activity as scavenger enzymes after wild ginseng administration dose-dependantly increased compared with butylated hydroxytoluene, a general radical scavenger. These data likely indicate that wild ginseng extract may act as inflammatory regulator in conjunction with inhibition of oxidant dependent metabolic activation in environmental contaminants-induced hepatic inflammation.

• Korean Journal of Microbiology
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• v.5 no.2
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• pp.79-85
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• 1967

Kim, Jong Hyup., (Div. of Biology, Atomic Energy Research Institute,Korea.;) Studies on the Cellulor Metabolism in Microorganisms as influenced by Gamma-irradiation(III): On the Changes of Free Amino acid Pool and content of Protein in Yeast clls irradiated by .gamma.-ray. 1. The strain of Saccharomyces cerevisiae had been cultured synchronously in aerobic condition and irradiatel by gamma-ray from the source of cobalt-60. Drying in vacuum oven at $90^{\circ}C$ C over 12 hours, then changes of protein content (Kjeldahl) and free amino acid pool have been assayed with use of spectrophotometer. Results obtained were compared with those of unirradiated normal cells. 2. It is proved that amount of protein content in the irradiated cells increases to seven percent more than those of normal cells in the same weight of dried samples. It seems like carbohydrate breakown had been stimulated by irradiation and that relative contents of protein shows higher values than those of normal in the same weight of samples. 3. The amount of free amino acid pool in the irradiated cells shows less value about ten percent than those of normal cells, and rate of decreasing is also weak than those of standard reagent solution of amino acid. We may assume that free amino acid pool would be protected against radiation damage in living cells and more stable than in vitro. 4. The component of free amino acid pool have been assayed on second dimensional paper chromatogram, and the identified amino acids are as follows; aspartic acid, serine, glutamic acid, cystine, lysine, glycine, threonine, histidine, arginine, tyrosine, phenylalanine, valine and leucine. 5. Distributional presence of free amino acids are identical to that of normal cells except arginine, it is cosumable that radiation effect is univerlsal to all amino acid. However it is obvious that there are differences in radiolabilities of amino acids in irradiated cells.