• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.38-45
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• 2007

Trichloroethylene (TCE) is a representative dense non-aqueous phase liquid (DNAPL) and has contaminated substance environments including soil and groundwater due to leakage and careless. DNPAL, has been treated by surfactant-enhanced aquifer remediation (SEAR). After application of SEAR, groundwater contains still surfactant as well as little amount of residual TCE. Permeable reactive barrier using zero-valent iron (ZW) is a very effective technology to treat the residual TCE in groundwater. In this study, the effect of the residual surfactant on the reductive dechlorination of residual TCE was investigated using ZVI. Mixed surfactant composed of nonioinic surfactant and cationic surfactant was used as a residual surfactant because of toxicity and enhancement of dechlorination rate. Structure of surfactant affected significantly the decrhlorination rate of TCE. Mixed surfactant system with relatively short polyethylene oxide (PEO) chain in nonionic surfactant, cationic surfactant did not affect TCE dechlorination rate. However, mixed surfactant system with relatively long PEO chain in nonionic surfactant shows that TCE dechlorination rate was significantly dependent on fraction of cationic surfactant and HLB of nonionic surfactant. Cationic surfactant with trimethyl ammonium group enhanced reductive dechlorination rate compared to that surfactant with pyridinium group.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.3
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• pp.237-246
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• 1995

Larvae of the freshwater shrimp, Macrobrachium nipponense were reared in the laboratory at constant condition $(25^{\circ}C,\;7\%o)$, and their feeding rate, oxygen consumption rate, and growth rate were measured in regular intervals of time during larval development. Regression equations describing rates of feeding, growth and respiration as functions of time during individual larval molt cycles were inserted in a simulation model in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Absolute values for feeding, growth, respiration and assimilation showed clear changes during the molt cycle, The absolute and specific values of respiration (R: R/C) showed small variation during the individual molt cycles. Significance of respiration in relation to growth (G) increased within the carbon budget, respiration rate (R/C) outbalanced growth rate (G/C) in late premolt. When the portion of metabolizable carbon is respired (R/G), metabolic coefficient was < 1 (i.e. R$(K_2)$ decreased concurrently, In cumulative carbon budget, total feeding was $491.54\;{\mu}g$ C/ind., assimilation was $85.3\%$, respiration was $47.7\%$, and growth was $37.6\%$ from hatching to postlarval stage.

• Health Policy and Management
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• v.9 no.4
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• pp.41-64
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• 1999

The major concern for this research is to discuss and to offer some solutions to bring the effectiveness of existing notifiable diseases reporting system over the physicians' attitudes of reporting, the actual condition of performance and the reasons of inertia in notifiable diseases reporting through examining the physicians of medical institutions in nationwide such as pediatrics, internal medicine and family medicine. The actual conditions of notifiable communicable diseases(NCD) reporting was surveyed by mail objectifying an internal medicine, pediatrics and family medicine in nationwide on the basis of stratified random sampling method divided into the classification of medical institutions and areas. As a result of survey. the rate of respondents showed 145 persons from physicians, 105 persons from hospitals. 120 persons from general hospitals, and 51 persons from tertiary hospitals. The total number of respondents were 421 and was rated 59.0 %. The analysis of collected survey went through a descriptive analysis primarily to grasp physicians' attitudes on the notifiable communicable diseases reporting, and then upon the dependent variables. Following are major findings obtained form the data analysis. 1. The results of a descriptive analysis on physicians' attitudes towards reporting NCD were as follows: First, the respondents who didn't know that yellow fever is reporting NCD were 11.0% of clinic, 10.5% of hospital. 5.0% of general hospital. 11.8% of tertiary hospital. and in case of hepatitis B, were 26.9% of clinic, 35.2% of hospital. 35.0% of general hospital. 23.5% of tertiary hospital. Second, The rate of physicians' knowledge on penalties of not reporting the NCD by their medical institution were 35.2% of clinic, 45.7% of hospital. 36.7% of general hospital. 62.7% of tertiary hospital. Third, among the no-reporting physicians in whole, the major reason of not reporting NCD were uncertainty of diagnosis(78.9%), no need to report(46.4%), no adequate actions from PHC(29.1%), no knowledge of the cases being notifiable ones in the order of their frequencies(30.4%), meddling from PHC(29.1%), concerning of patient's privacy(26.3%). 2. To analyze the characteristics related to the physicians' behaviors to report NCD, univariate and multiple logistic regression analyses were applied to the variables related to physician, 4 medical facility, PHC, and reporting system. The result were as follows: First, the result of the univariate analysis on physicians' attitude to report NCD and characteristics related to reporting in odds ratio was in the case of hospital. 3.4 times higher positive responses on physicians' attitude to report NCD came up as compared to the clinic. Second, the result of the univariate analysis on physicians' action of reporting NCD and characteristics related to reporting by the classification of medical institutions showed that the odds ratio of hospital was 2.3 times, the odds ratio of general hospital was 2.0 times, the odds ratio of tertiary was 6.8 times significantly higher than clinic. And the medical institution with significantly higher positive attitudes rate by multiple logistic regression analysis was hospital that rated 2.5 times significantly higher than clinic. Also in the PHC related characteristics of reporting, the rate of action in reporting NCD was significantly higher in medical institution that were endowed with the good condition of reporting. In multiple logistic regression analysis, the medical institution that has a good conditions of reporting showed a significantly higher positive rate on the action of reporting than the others.

• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.27-36
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• 2004

The corrosion rate measurement procedure for the permanent ground anchors using polarization resistance measurements and electrochemical impedance spectroscopy is presented in this paper. The polarization resistance measurements were used to determine the correlation between corrosion rate in the steel and soil characteristics. The electrochemical impedance spectroscopy was used to predict the time dependent corrosion reaction and evaluate the different type of coating systems and the effect of cement grouting on the corrosion attack under various conditions. The results indicate that a low pH soil is a good indicator of a corrosive soil. The low pH soil condition (<5) in both clay and sand has a significant effect on the corrosion reaction of steel members in permanent found anchors. In the case of neutral and alkaline conditions beyond pH 6 in clay and sand, no consistent acceleration of corrosion was measured and the corrosion rate was constant regardless of variations of soil pH levels. Laboratory test data for porcelain clay indicate that the change of soil pH level has a small influence on the corrosion reaction in the steel member. The use of cement footing in the bonded length is sufficient to decrease the corrosion rate to a level close to 0.003∼0.01mm/y at the end of the given period. With epoxy and fusion bonded epoxy coating, the steel specimens remained unaffected and retained the original condition. It is suggested that epoxy and fusion bonded epoxy coating can provide effective protection against corrosion for a long time even in aggressive environment.

• Quality Improvement in Health Care
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• v.9 no.2
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• pp.210-228
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• 2002

Background: The purpose of this research was to examine the fall incidence rate and its related factors of fall in inpatients. Methods: The data were collected from the 138 fall incident reports in one tertiary hospital in Seoul from April 1st 1999 to September 30th 2001. The Fall Incident Report Form was originally developed based on that of Massachusetts General Hospital revised in 1995. And this was modified for this survey by the collaborating work of QI team including researcher and department of nursing service of this particular hospital. The contents of Fall Incident Form were general characteristics of patient. factors related to fall. types and places of fall. circumstances, nursing interventions. and outcome. Results: 1) The incidence rate of fall was 0.08% of total discharged patients and 0.081 per 1000 patient-day. This incidence rate is much lower than that of several hospitals in USA. This finding might result from the different incidence report system of each hospital. 2) The characteristics of fall-prone patient were found as follows. They were mostly over 60 years old, in alert mental status, ambulatory with some assistance, and dependent on ambulatory device. The types of diseases related high incidence rate were cerebrovascular disease(3.2), hypertension(1.6), cardiovascular disease(1.4), diabetes(1.3) and liver disease(0.6). 3) The majority of fall events usually occurred m bed. bedside(walking or standing) and bathroom in patient room. Usually they were up on their own when they fell. And there were more falls of elderly occurred during night time than day or evening. 4) 63.8% of fall events resulted in physical injuries such as fracture and usually the patients had diagnostic procedures and some treatment(ex. suture) which caused additional cost to the patients and their families. 5) The found risk factors of fall were drugs(antihypertensive drug, diuretics) and environmental factors like too high bed height, long distance of bedside table and lamp switch, and slippery tile of bathroom floor. Conclusion: Considering these results, every medical and nursing staff should be aware of the risk factors of patients in hospital, and should intervene more actively the preventive managements, specially for the elderly patients during night. Therefore, it is recommended that the development of Fall Prevention Programs based on these results.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.28 no.4
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• pp.191-201
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• 2016

A stochastic process has been used to develop a condition-based model for preventive maintenance of armor units of rubble-mound breakwaters that can make a decision the optimal interval at which some repair actions should be performed under the perfect maintenance. The proposed cost model in this paper based on renewal reward process can take account of the interest rate, also consider the unplanned maintenance cost which has been treated like a constant in the previous studies to be a time-dependent random variable. A function for the unplanned maintenance cost has been mathematically proposed so that the cumulative damage, serviceability limit and importance of structure can be taken into account, by which a age-based maintenance can be extended to a condition-based maintenance straightforwardly. The coefficients involved in the function can also be properly estimated using a method expressed in this paper. Two stochastic processes, Wiener process and gamma process have been applied to armor stones of rubble-mound breakwaters. By evaluating the expected total cost rate as a function of time for various serviceability limits, interest rates and importances of structure, the optimal period of preventive maintenance can easily determined through the minimization of the expected total cost rate. For a fixed serviceability limit, it shows that the optimal period has been delayed while the interest rate increases, so that the expected total cost rate has become lower. In addition, the gamma process tends to estimate the optimal period more conservatively than the Wiener process. Finally, it is found that the more crucial the level of importance of structure becomes, the more often preventive maintenances should be carried out.

• Archives of Plastic Surgery
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• v.36 no.5
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• pp.617-622
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• 2009

Purpose: Endoscopic transnasal correction of the blowout fractures has many advantages over other techniques. But after removal of packing material, there were some patients with recurrence of preoperative symptoms. Authors tried to make a quantitative anterograde analysis of orbital volume change over whole perioperative period which might be related with recurrence of preoperative symptoms. Methods: 10 patients with pure medial wall fracture(Group I) and 10 patients with medial wall fracture combined with fracture of orbital floor(Group II) were selected to evaluate the final orbital volume change, who took 3 CT scans, pre-, postoperative and 4 months after packing removal. By multiplying cross - section area of orbit in coronal view with section thickness, orbital volume were calculated. Then, mean orbital volume increment after trauma, mean orbital volume decrement after endoscopic correction and volume increment after packing removal were found out. And we tried to find correlations between type of fracture, initial correction rate and final correction rate. Results: The mean orbital volume increment of the fractured orbits were 7.23% in group I and 13.69% in group II. After endoscopic surgery, mean orbital volume decrement were 11.0% in group I and 12.46% in group II. Mean volume increment after packing removal showed 3.10% in group I and 6.50% in group II. The initial correction rate(%) showed linear correlation with final correction rate(%) after packing removal. And there were negative linear correlation between increment percentage of orbital volume by fracture and final correction rate(%). Conclusion: Orbital volume was proved to be increasing after removal of packing or foley catheter and it was dependent upon type of fracture. Overcorrection should be done to improve the final result of orbital blowout fracture especially when there are severe fracture is present.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.573-580
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• 2017

The oxicity assesment of Phenanthrene (PHE) has been investigated by using the rate (r) of survival and population growth in rotifer Brachionus plicatilis. The survival rate was determined after 24 h of exposure to PHE. The survival rate of PHE had no effect at a maximum of $300mg\;L^{-1}$. The r was determined after 72 h of exposure to PHE. It was observed that r in the controls (absence PHE) was greater than 0.5, but that it suddenly decreased with an increased concentration of PHE. PHE reduced r in a dose-dependent manner and a significant reduction occurred at a concentration of greater than $37.5mg\;L^{-1}$. The $EC_{50}$ value of r in PHE exposure was $63.7mg\;L^{-1}$. The no-observed-effect-concentration (NOEC) of r in PHE exposure was $18.8mg\;L^{-1}$. The lowest-observed-effect-concentration (LOEC) of r in the PHE exposure was $37.5mg\;L^{-1}$. From the results, the concentration of PHE (greater than $37.5mg\;L^{-1}$) has a toxic effect on the r of B. plicatilis in natural ecosystems. These results(including NOEC, LOEC and $EC_{50}$) might be useful for the Polycyclic aromatic hydrocarbons(PAHs) toxicity assessment in marine ecosystems.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.18-27
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• 2022

In this study, the time-dependent chloride ingress behavior in GGBFS concrete was evaluated considering marine exposure conditions and the properties of concrete mixtures. The concrete mixture for this study had 3 levels of water to binder ratio and the substitution rate of GGBFS, and outdoor exposure tests were performed considering submerged area, tidal area, and splash area. According to the evaluation results of diffusion coefficient considering properties of concrete mixtures, as the substitution rate of GGBFS increased, the decreasing rate of the diffusion coefficient decreased based on exposure periods of 730 days(2 years). As the evaluation result of the diffusion behavior according to the marine exposure conditions, the diffusion coefficient was evaluated in the order of submerged area, tidal area, and splash area. In tidal area, a relatively high diffusion coefficient was evaluated due to the repetition of wet and dry seawater. In this study, the effects of GGBFS substitution rate on the decreasing behavior of apparent chloride diffusion coefficient was analyzed in consideration of exposure conditions and periods. Linear regression analysis was performed with apparent chloride diffusion coefficient as output value and GGBFS substitution rate as input value. After 730 days of exposure, the effect of GGBFS on diffusion coefficient was significantly reduced. Even for OPC concrete, after 730 days, the diffusion coefficient was as low as that of GGBFS concrete, so the gradient of the regression equation decreased significantly. It is thought that improved durability performance for chloride ingress can be secured before 730 days through the use of GGBFS.

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.454-459
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• 2009

The secondary growth of garlic depreciates the quality of a bulb and, in the worse cases, makes it difficult to be used as a seed bulb due to many insertions of small cloves in the seed bulb. Therefore, the effect of soil temperature, seedtime, and fertilization rate on the secondary growth of the big bulbils of Namdo garlic has been examined. When we analyzed into the growth characteristics of big bulbils of Namdo garlic under different fertilizer application levels (50% increased fertilization, experimental fertilization and 50% decreased fertilization), the plant height, numbers of leaf, sheathe diameter, leaf length, and leaf width were the best in 50% increase of the test rate of fertilizer. The occurrence rates of secondary growth were 34.2% in 50% decrease of the test rate of fertilizer, 44.3% in the test rate, and 54.1% in 50% increase of the test rate of fertilizer. In other words, the occurrence rate of secondary growth increased by increasing the fertilization rate. While the average harvested bulb weight were 34.1g in 50% decrease of the test rate of fertilizer, 35.1g in the test rate of fertilizer, and 33.9g in 50% increase of the test rate of fertilizer, there were no changes in the number of cloves under different fertilization rates. As the correlation diagram between the soil temperature and occurrence of the secondary growth showed very high relation with 0.892~0.997, the secondary growth in cultivation of Namdo garlic big bulbils had considerably close correlation with the soil temperature. As the earlier the seedtime was, the growth of the above-groundparts including the plant height, numbers of leaf, and sheath diameter were the better. The averages of bulb weight were 36g in the mid September sowed seed bulb, 29.6g in the late September sowed seed bulb, and 27.9g in the early October sowed seed bulb. Overall, our results showed that the bulb size is dependent on the seedtime and the seedtime has no particular effects on the secondary growth.