• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.547-555
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• 2018

In addition to North America and Europe, Korea is also responding to the toxic damage caused by the production and distribution of chemicals. Methods for assessing bio-toxicity of harmful substances have been widely introduced, but it is required of quantitative and speedy information for modeling. For 6 heavy metals, as zinc, copper, chrome, cadmium, mercury and lead, bio-toxicity assessment and kinetics model were constructed using Vibrio fischeri which is widely used luminous bacteria. The degree of luminescence activity and the toxicity of heavy metals were relative limunescence unit, RLU measured as by using a photomultiplier embedded device. The toxicity was assessed by the concentration levels giving under 20% lethality and lethal concentration, $EC_{50}$. In the results, the toxicity order were followed from mercury, lead, copper, chrome, zinc and cadmium. $EC_{{50},{\infty}}$ obtained by trends of $EC_{50}$ by time follows had highly linear agreement with main parameters of bio-toxicity modelling. The average error rates of the reproduced lethality obtained from DAM and TDM model on the basis of body residue, were 10.2% for mercury, lead, copper, chrome and 20.0 for the all 6 methals.

• Journal of the Korea Society of Computer and Information
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• v.27 no.10
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• pp.43-57
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• 2022

In this paper, we propose a method of analyzing research papers published by researchers belonging to university departments in the field of disaster & safety for the scientometric analysis of the research status in the field of disaster safety. In order to conduct analysis research, the dataset constructed in previous studies was newly improved and utilized. In detail, for research papers of authors belonging to the disaster prevention and safety engineering type department of domestic universities, institution identification, cited journal identification of references, department type classification, disaster safety type classification, researcher major information, KSIC(Korean Standard Industrial Classification) mapping information was reflected in the experimental data. The proposed method has a difference from previous studies in the field of disaster & safety and data set based on related keyword searches. As a result of the analysis, the type and regional distribution of organizations belonging to the department of disaster prevention and safety engineering, the composition of co-authored department types, the researchers' majors, the status of disaster safety types and standard industry classification, the status of citations in academic journals, and major keywords were identified in detail. In addition, various co-occurrence networks were created and visualized for each analysis unit to identify key connections. The research results will be used to identify and recommend major organizations and information by disaster type for the establishment of an intelligent crisis warning system. In order to provide comprehensive and constant analysis information in the future, it is necessary to expand the analysis scope and automate the identification and classification process for data set construction.

• Journal of Korean Ophthalmic Optics Society
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• v.15 no.4
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• pp.389-397
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• 2010

Purpose: This study was to investigate the changes of refractive error and astigmatism associated with age in Korean subjects between the ages of 6 and 80 years during 10-year period. Methods: 220 normal subjects (345 eyes) who visited ophthalmic clinic was recruited and followed for 10 years between 1999 and 2009, cycloplegic manifest refraction being performed annually. Visual acuity was tested on a Han's chart. Results: The mean 10-year change in the spherical equivalent refraction (SER) of age 6 to 10 years old and 10 to 20 years was -3.649D and -2.165D respectively. There was no change of refractive error in age 21 to 40 years. The myopic shift decreased with age from 41 up to 69 years but increased slightly in patients 70 years and older; the hyperopic shift showed the opposite trend. The distribution of refractive error over the 10 years in aged 6 to 10 and 11 to 20 years was shifted myopic. The incidence of medium (> -3.01D) to high myopia at age 6 to 10 years was 4.8% and after 10 years was 62.5%. The 10-year change of astigmatism axis was in "with the rule" direction for younger age group and in a "against the rule" direction for older subjects. Conclusions: This study has documented refractive error changes in Korean subjects and confirmed reported trends of myopic shift from age 6-20 years and hyperopic shift before age 70 years and a myopic shift thereafter. The axis of astigmatism turns to "against the rule" after 40's.

• Journal of Environmental Health Sciences
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• v.42 no.1
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• pp.41-52
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• 2016

Objectives: Scrub typhus is one of the most prevalent vector-borne diseases. It is caused by Orientia tsutsugamushi, which is transmitted when people are bitten by infected chigger mites. This study aims at quantifying the association between the incidence of scrub typhus and meteorological factors in Jeollabuk-do Province over the period 2001-2015. Methods: Reported cases of scrub typhus were collected from the website of the Disease Web Statistical System supported by the Korea Centers for Disease Control and Prevention (KCDC). Simultaneous meteorological data, including temperature, rainfall, relative humidity, and sunshine duration were collected from the website of the National Climate Data Service System by the Korea Meteorological Administration. Correlation and regression analyses were applied to identify the association between the incidence of scrub typhus and meteorological factors. Results: The general epidemiological characteristics of scrub typhus in Jeollabuk-do Province were similar to those nationwide for sex, age, and geographical distribution. However, the annual incidence rate (i.e., cases per 100,000) of scrub typhus in Jeollabuk-do Province was approximately four times higher than all Korea's 0.9. The number of total cases was the highest proportion at 13.3% in Jeonbuk compared to other regions in Korea. The results of correlation analysis showed that there were significant correlations between annual cases of scrub typhus and monthly data for meteorological factors such as temperature and relative humidity in late spring and summer, especially in the case of temperature in May and June. The results of regression analysis showed that determining factors in the regression equation explaining the incidence of scrub typhus reached 46.2% and 43.5% in May and June. Using the regression equation, each 1oC rise in the monthly mean temperature in May or June may lead to an increase of 38 patients with scrub typhus compared to the annual mean of incidence cases in Jeollabuk-do Province. Conclusion: The result of our novel attempts provided rational evidence that meteorological factors are associated with the occurrence of scrub typhus in Jeollabuk-do. It should therefore be necessary to observe the trends and predict patterns of scrub typhus transmission in relation to global-scale climate change. Also, action is urgently needed in all areas, especially critical regions, toward taking steps to come up with preventive measures against scrub typhus transmission.

• Journal of Korea Water Resources Association
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• v.52 no.7
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• pp.505-514
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• 2019

Our country is making efforts to manage water resources efficiently. In the future, It is necessary to develop a plan after subdividing the basin considering regional problems and water use, topographical and climatic characteristics. This study constructed water supply and demand system based on the standard watershed unit for water shortage evaluation considering spatial resolution. In addition, water shortage were calculated and compared using the MODSIM model in the Han-river basin. As a result, the average water shortage occurring during the 49 years (1967-2015) was 129.98 million $m^3$ for the middle watershed unit and 222.24 million $m^3$ for the standard watershed unit, resulting in a difference of about 2.1 billion m3. However, the trends and distribution of water shortage occurrence were very similar. The reason for this is that, in the case of the Middle watershed unit analysis, water shortages are calculated for the demand for living, industrial, and agricultural water for the representative natural flow value, assuming that all the water can be used in basin. The standard basin unit analysis showed that the difference between the fractionated supply and demand resulted in a large water shortage due to the relatively small amount of available water, and that the main stream did not show water shortage due to the ripple effect of the return flow. If the actual water use system is considered in the model as well as the subdivision of the spatial unit, it will be possible to evaluate the water supply and demand reflecting the regional characteristics.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.5
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• pp.533-549
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• 2024

Soil conditioning is a critical process when tunneling with an earth pressure balance (EPB) shield tunnel boring machine (TBM) to enhance performance. To determine the optimal additive injection conditions, it is important to understand the rheological properties of conditioned soil, which is typically assessed using a rheometer. However, a rheometer cannot simulate the actual process of muck discharge in a TBM. Therefore, in this study, a scaled-down model of an 8-meter-class EPB shield TBM chamber and screw conveyor, reduced by a factor of 1:20, was fabricated and its applicability was evaluated through laboratory experiments. A lab-scale model experiment was conducted on artificial sandy soil using foam and polymer as additives. The experimental results confirmed that screw torque was consistent with trends observed in previous laboratory pressurized vane shear test data, establishing a positive proportional relationship between screw torque and yield stress. The muck discharge efficiency according to foam injection ratio (FIR) showed similar values overall, but decreased slightly at 60% of FIR and when the polymer was added. In addition, the pressure distribution generated along the chamber and screw conveyor was assessed in a manner similar to the actual EPB TBM. This study demonstrates that the lab-scale screw conveyor model can be used to evaluate the shear properties and muck discharge efficiency.

• Korea Journal of Hospital Management
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• v.6 no.1
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• pp.120-146
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• 2001

This study was carried out to provide the essential information in improving the graduate medical education in Korea. For the study, a survey targeting the directors of GME of nationwide teaching hospitals was performed with a questionnaire asking the questions such as the director's perception on the quality of GME, trainees' salary level, trainees' specialty selection tendency, training system and its duration. The collected data were analyzed using t-test, ANOVA, and $x^2$-test. The results were as follows: 1. The survey were executed on 240 teaching hospitals in Korea and the response rate was 66.2% (159 hospitals replied). 2. The bigger a hospitals is the better in Quality of education. Larger hospitals tend to have better status in all items including medical specialists' experience, contents of medical curriculum, general environment for medical education and medical trainees's salary level. The result supported the general perception on the positive relationship between hospital size and Quality of GMA. 3. Providing convenience for medical trainees who prepares for the medical specialist Qualifying examination didn't affect the results of the examination. 4. The directions of GME have a perception that the trainees give positive impact on financial performance of their hospitals. This seems to be one of the reasons that hospitals try to retain as many trainees as possible. 5. The directors of GME considered medical trainees as an educate, and most of them responded positively on the need of governmental supports for the education cost and the trainee's salary. Considering above results, it seems that GME would get more social attention and the trainees' impact on hospitals operation would be increased more than before. In response to these trends, hospitals would find out the ways to lower dependency on trainees, and this change of attitude of hospitals on the GME would cause problems in operation of hospitals and GME itself. In order to prevent these problems the policy on GME should be directed in following ways. 1. The contents of Qualifying examination for specialist should be improved. 2. The curriculum of GME should be strictly followed. 3. The status of trainee in a hospital has to be defined as eductee. 4. Government has to support a half of the education cost and salary of trainee. 5. The distribution of the trainee among the hospital group have to be based on total available. 6. The financial support and welfare of trainee should be improved gradually and systematically.

• Korean Journal of Microbiology
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• v.21 no.2
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• pp.71-78
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• 1983

The number of aerobic free-living nitrogen fixation bacteria and factors in soil at different stands covered with Pinus rigida, Quercus acutissima and Zoysia japonica in Cheongju area were investigated from Feb. to Sept 1981. 1. The numbers of $N_2-fixation$ bacteria, according to the seasonal changes, increased gradually from winter to spring and summer. But the growth pattern revealed some differences in accordance with plant cover stands : the numbers increased abruptly in May at Pinus, May-June at Quercus and Apr. May at Zoysia stand. The pick of numbers represented in Aug. Sept, at Pinus, Jul-Aug. at Quercus and May-Jun. at Zoysia stand, respectively. 2. The interrelationship between the monthly changes of enviotnmental factors and numbers of $N_2-fixation$ bacteria at different stands, mainly depends upon the soil temperature than other soil factors (r=0.71-0.84). The numbers of $N_2-fixation$ bacteria may increase 5-7 times according to increase $10^{\circ}C$ of soil temperature, and optimal range was $20{\sim}30^{\circ}C$ for growth. Equation of the interrelation between soil temperature and numbers could be stated as follows : log y=ax+b. 3. In the case of high soil temperature, the bacterial numbers presented high level in drought periods. Therefore, the $N_2-fixation$ bacterial species in these soil seem to consist of resistant to desication. 4. The influence of soil organic matter for growth of $N_2-fixation$ bacteria indicated low conrelation. The reason may seen the content of organic matter in these soil existed abundantly above the quantities of limitation for growth. 5. In artifical gradients, the $N_2-fixation$ bacteria were predominated at $20{\sim}30^{\circ}C$ same as natural condition, pH7-8, and 20-30% of soil water contents. 6. The vertical distribution of bacteria marked decreasing trends from surface to lower layers, and the decreasing degree was shown well in Zoysia, Quercus and Pinus stand in order. But in the trees, the numbers increased at 30cm layer estimated the region of root than 20cm layer. 7. Both catalase megative and positive group of $N_2-fixation$ bacteria in soil increased according to the rise of the soil temperature. Catalase positive group was revealed as dominant group in winter, and catalase negative group revealed in summer. The change of dominant pattern was shown during Feb. to Apr.

• Journal of Ecology and Environment
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• v.38 no.4
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• pp.517-528
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• 2015

Litter decomposition is an important process in terrestrial ecosystem. However, studies on decomposition are rare, especially in evergreen broadleaf trees. We collected the leaf litter of five evergreen broadleaf trees (Daphniphyllum macropodum, Dendropanax morbifera, Castanopsis cuspidata var. thunbergii, Machilus thunbergii and Quercus acuta), and carried out a decomposition experiment using the litterbag method in Ju-do, Wando-gun, Korea for 731 days from December 25, 2011 to December 25, 2013. Among the five experimental tree species, C. cuspidata var. thunbergii distribution was limited in Jeju Island, and D. macropodum was distributed at the highest latitude at Mt. Baekyang (N 35°40′). About 2% of the initial litter mass of D. macropodum and D. morbifera remained, while 20.9% remained for C. cuspidata var. thunbergii, 30.4% for M. thunbergii, and 31.6% for Q. acuta. D. macropodum litter decayed four times faster (k = 2.02 yr^-1) than the litter of Q. acuta (k = 0.58 yr^-1). The decomposition of litter was positively influenced by thermal climate such as accumulated mean daily air temperature (year day index) and precipitation, as well as by physical characteristics such as thickness (R²=0.939, P = 0.007) and specific leaf area (SLA) (R² = 0.964, P = 0.003). The characteristics of chemical composition such as lignin (R² = 0.939, P = 0.007) and water-soluble materials (R² = 0.898, P = 0.014) showed significant correlations with litter decomposition. However, the nutrients in litter showed complicated species-specific trends. The litter of D. macropodum and D. morbifera had fast decomposition despite their low nitrogen concentration and high C/N ratio. This means that the litter decomposition was more strongly affected by physical characteristics than chemical composition and nutrient content. On the other hand, the litter of Q. acuta which had the slowest decay rate had a high amount of N and low C/N ratio. Thus, the decomposition of Q. acuta litter was more affected by the P content of the litter than the N content, although all litter had similar physical characteristics.

• Korean Journal of Occupational Health Nursing
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• v.14 no.2
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• pp.93-107
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• 2005

Purpose: The purpose of this study is to identify the trends of studies on work-related musculoskeletal disorder and to suggest the direction of future research. Method: 144 research thesis for a degree on work-related musculoskeletal disorder were systematic reviewed and published from Jan. 1990 to Mar. 2005. The analyzed using descriptive statistics, an actual number, percentage. Result: As its result the work-related musculoskeletal disorder research which is announced from domestic the doctorate dissertation at the 2004 year 42 the most many 144 dissertation middle most to be 129 in master degree dissertation was 15 in Ph D degree. Dissertation contents character the contents against the result relation that it analyzes especially and a condition and an obstacle was many most at 84. Research plan in most description investigation research 121 the dissertation field to be the especially public health (hygiene, industry and environment) at this 57 most many research object person distribution manufacturing industry in the research object one dissertation was many most at the 40. The tools which are used in each measurement in the question tool which it uses most the question price of land which uses the condition investigation ticket which it made from the NIOSH and the ANSI most many 33, the hazard which analyzes a work attitude in the tool which it uses the RULA was many most at 14. In the stress test tool social psychological healthy measurement PWI (Psychological Wellbeing Index) the dissertation which uses the Job Strain of the Karasek Model to be many most at 19 PWI (Psychological Wellbeing Index) 7 easy use. Work-related musculoskeletal disorder measurement hazard in physiological index and the machinery and tools which it uses there were 9 researches to use an electromyogram most plentifully. With the effect goes to a work-related musculoskeletal disorder they are 33 where the age is many most from general quality. From healthy act with the relation of smoking the year to be many from 16 dissertations. Work of the corpse an attitude (the attitude which is inappropriate) with 5 and the work market the work burglar is many most at 9, the society-support of 36 where the stress is many psychologically most, the stress and service also the most many duty discretion (authority and autonomy) is 6 at the duty demand boat song 9. The service career to be many is 22 of extraordinarily with relation of service. Conclusion: It is recommended the research which it sees being limited in only domestic thesis for a degree the international comparative study to become accomplished. It comes to think with the fact that it will be necessary to make the protocol which it conforms in the civil official guide the test researches for the protocol or arbitration program which is standardized are necessary. Prevention and the civil official of work relation bones and sinews standing total disease hazard scientific base one program is necessary with base.