• Economic and Environmental Geology
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• v.54 no.2
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• pp.299-308
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• 2021

Fe(II) released from mining activities is precipitated as various Fe(III)-oxyhydroxides when exposed to an oxidizing environment including mine drainage. Ferrihydrite, one of the representative precipitated Fe(III) minerals, is easy to adsorb heavy metals and other pollutants due to the large specific surface area caused by very low crystallinity. Ferrihydrite is transformed to thermodynamically more stable goethite in the natural environment. Hence, information on the transformation of ferrihydrite to goethite and the related mobility of heavy metals in the acid mine drainage is important to predict the behaviors of those elements during ferrihydrite to goethite transition. The behaviors of heavy metals during the transformation of ferrihydrite to goethite were investigated for core samples collected from an AMD treatment system in the Heungjin-Taemaek coal mine by using X-ray diffraction (XRD), chemical analysis, and statistical analysis. XRD results showed that ferrihydrite gradually transformed to goethite from the top to the bottom of the core samples. Chemical analysis showed that the relative concentration of As was significantly high in the core samples compared with that in the drainage, indicating that As was likely to be adsorbed strongly on or coprecipitated with iron oxyhydroxide. Correlation analysis also indicated that As can be easily removed from mine drainage during iron mineral precipitation due to its high affinity to Fe. The concentration ratio of As, Cd, Co, Ni, and Zn to Fe generally decreased with depth in the core samples, suggesting that mineral transformation can increase those concentrations in the drainage. In contrast, the concentration ratio of Cr to Fe increased with depth, which can be explained by the chemical bond of iron oxide and chromate, and surface charge of ferrihydrite and goethite.

• Composites Research
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• v.34 no.3
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• pp.192-198
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• 2021

Due to enormous market growing of electric vehicles without combustion engine, reducing unwanted BSR (buzz, squeak, and rattle) noise is highly demanded for vehicle quality and performance. Particularly, innerbelt weatherstrips which not only block wind noise, rain, and dust from outside, but also reduce noise and vibration of door glass and vehicle are required to exhibit high damping properties for improved BSR performance of the vehicle. Thermoplastic elastomers (TPEs), which can be recycled and have lighter weight than thermoset elastomers, are receiving much attention for weatherstrip material, but TPEs exhibit low material damping and compression set causing frictional noise and vibration between the door glass and the weatherstrip. In this study, high damping EPDM (ethylene-propylene-diene monomer)/PP (polypropylene) thermoplastic vulcanizates (TPV) were investigated by varying EPDM/PP ratio and ENB (ethylidene norbornene) fraction in EPDM. Viscoelastic properties of TPV materials were characterized by assuming that the material damping is directly related to the viscoelasticity. The optimum material damping factor (tanδ peak 0.611) was achieved with low PP ratio (14 wt%) and high ENB fraction (8.9 wt%), which was increased by 140% compared to the reference (tanδ 0.254). The improved damping is believed due to high fraction of flexible EPDM chains and higher interfacial slippage area of EPDM particles generated by increasing ENB fraction in EPDM. The stick-slip test was conducted to characterize frictional noise and vibration of the TPV weatherstrip. With improved TPV material damping, the acceleration peak of frictional vibration decreased by about 57.9%. This finding can not only improve BSR performance of electric vehicles by designing material damping of weatherstrips but also contribute to various structural applications such as urban air mobility or aircrafts, which require lightweight and high damping properties.

• Journal of the Korean Geographical Society
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• v.30 no.1
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• pp.35-56
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• 1995

During the last two decades, Korea has achieved remarkable economic growth. In this process the nation has become urbanized and industrialized. But we have also encountered widening regional disparity, housing shortage of larger cities, transportation congestion, environmental pollution and many other problems. Rapid increasing urbanization and continuous migration toward Seoul since the late 1960s have been one of the major concerns of government. Government has sought ways to moderate the population increase in Seoul. The regulation which include new town development near Seoul and dispersion strategies of higher education and other administration and living facilities outside of Seoul havemade a great expansion of the spatial influence of Seoul city. Seoul metropolitan reaion has evolved as the most powerful center of political and economical spaces. Generally within a metropolitan region, there exists a growing mutual interdependence economically, as well as socially between a central city and its surrounding area. Seoul metropolitan region manifests itself not only as a coherent system of urbanized regions, but also as an integral part of the daily urban system. The surrounding Gyunggi province and Seoul city become closely linked both economically and functionally, constituting true functlonai urban system. This study is primarily undertaken with the purpose of delineation of the sphere of influence of Seoul city in 1990. At the time of 1985, Seoul metropolitan region was delineated according to the result of the study which was performed by Korea Research Institute for Human Settlements. Afterward, the rapid speed of metropolitanization process with dramatic increase in mobility through the provision of wider transportation system across the Capital region have evolved, resulting in the great expansion of the spatial influence of Seoul city. So this study examines the expanded area of Seoul metropolitan regin during the period of 1985-90. In order to delineate Seoul metropolitan region, the indices of urbanization and functional linkage are selected. Variables included in the measurement of the urbanization level are agricultural structure, population characteristics, manufacturing and service industries, and cultural aspects such as newspaper circulation, the ratio of car ownership and piped water supply. Variables included in the measurement of functional linkage are commuting, shopping pattern, centralized service such as medical facilities and trade of agricultural products. The standardization method and factor analysis are employed in making the delineation of Seoul metropolitan region. According to the result of this study, 2 cities, 8 Eups and 46 Myuns are included Seoul metropolitan region in 1990. If we compare this delineated area in 1990 to that of 1985, we can find the distinctive pattern of expanded axes according to the main transportation routes such as Seoul-Suweon, Seoul-Gwangju, Seoul-Incheon. In 199O, all the Gyunggi province, except a few Myuns located at the north and northwest part of Gyunggi province, are included in Seoul metropolitan region. Furthermore, this study attempts to the analysis of regional structure of Seoul metropolitan region according to the functional characteristics of each city and Gun. Variables included in this analysis are the new residential function, manufacturing function, service function, education and infermation function, public facility function and agricultural function. Factor analysis and cluster analysis are employed in making regionalization. Seoul metropolitan reaion is subdivided into four subregions which reflect different functional specialization. The first group is the specialized region of newly formed residential function. The second group is the specialized reaion of manufacturing function. The third group is the specialized region of service function. And the fourth group has little specialized in terms of manufacturing, service, and residential function. But this region has some potentiality of development when Seoul metropolitan region grow continuously. Seoul metropolitan region accounted for 43% of national population, despite 11.8% of national land size in 1990. Although Seoul metropolitan region enjoys important agglomeration economies, it also has huge social cost in the form of transportation congestion, housing shortage, rapid increase of land value, environment pollution, and etc. Efficient metropolitan plan making is a vital element in promoting Seoul's economic development and providing high quality living environment at low cost. In the light of the result of this study, the outer ring of Seoul metropolitan region, especially northeastern part, are underdeveloped compared to overdeveloped southwestern area. It is needed to develop the guidelines for the implement of the growth control and management plan, inducing more balanced development for whole Seoul metropolitan reaion.

• The Korean Nurse
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• v.32 no.5
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• pp.66-77
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• 1994

The purpose of this study was to develop a new nursing unit which can meet changing health care needs, enhance patients' satisfaction and nurses' job satisfaction, and finally guarantee quality nursing care with present manpower. For this, one medical unit was selected as a unit for quality care. And one medical unit which is similar in staffing and patients' characteristics was selected as a control unit. To assess present problems and identify the remedies to the problems a hospital-wide survey and a workshop were performed. According to the survey results, educational programs and improvement of the facilities and equipment supply system, managereal support for interdepartmental cooperation and intensification of bed-side nursing care were adopted as main principles for operating model unit, This model unit was operated for 3 months from Sep. 1, 1992 to Nov. 30, 1992. To evaluate the effectiveness of the model unit, derect/indirect nursing care hours, patients' satisfaction to nursing care, nurses' job satisfaction, and quality care index were measured. Direct/indirect nursing care hours were compared with that of the control unit, and patients' and nurses' satisfaction and quality care index were measured before and after operating model unit and compared with each other. The results of the study were as follows; 1. In the model unit mean direct nursing care hours per cach shift was 146.88 minutes and indirect nursing care hours was 354.72 minutes. The ratio of the direct nursing care hour to indirect nursing hour was 29.6 ; 70.4 and that of the control unit was 26.9 : 73.1. Direct nursing care hour in model unit was longer than that of the control unit. But, the difference was not significant. In subcategories of direct nursing care, the time spent in mobility and exercise, conservation of body temperature, hygiene, and communication and health education were longer than that of the con" trol unit. 2. Indirect nursing care hour in model unit was shorter than that of the control unit. But, the difference was not significant. In subcategories of indirect nursing care, the time spent in drug management and ward arrangement was shorter than that of the control unit. 3. Patients' satisfaction to nursing care was increased significantly after operating the model unit (T=-3.48, P=-0.002) and satisfaction to subcategories of physical comfort measure, psychological cate, and unit management components were significantly higher than before. 4. In the model unit, nurses' total job satisfaction was increased significantly after operating the model unit(Z=2.1004, P=.0357) and satisfaction to subcategory of satisfaction to administration was significantly higher than before (Z=-2.0732, P=.0382). 5. After operating the model unit, quality care index was increased from 89 to 93. With this results, it can be summarized that all the measures tried for quality care, such as educational programs, managereal support for interdepartmental cooperation, and improvement of the equipment and facility provision resulted in partial increase in direct nursing care hours, nurses satisfaction to their job and patients' satisfaction to nursing care. In can be postulated that managereal support and motivation without proper staff supplementation is not enough for increasing direct nursing care hours. And for the enhancement of the level in clinical nursing, and staff supplement must be considered sincerely and the measures for reducing indirect nursing care hours, such as computerization of nursing care activities, improvement of facilities and equipment and facilities supply system, must be instituted in addition.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.22-32
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• 1990

Associations between type A behavior Pattern (TABP) and parental social control were examined by a questionnaire survey in a sample of 803 undergraduates of the three universities in Daegu city in 1988. TABP was assessed by the Student Jenkins Activity Survey (SJAS, short form) and social control of parents by Bernstein and Brandis' Index of control and communication which were both dichotomized by median. The mean age of the sample was 20.7 (standard deviation, 2.2) and mean of total score of SJAS was 5.6 with its standard deviation and median, 2.7 and 5, respectively. In stratified analysis for TABP-social control association by the native place, sex and socioeconomic status (SES), males of rural origin with low SES showed odds ratio (OR), 2.49 but those with high SES 0.40. For females of rural origin, those with low SES showed OR, 1.02, whereas those with high SES did 0.35. For those who was of urban origin, males with low SES had OR 1.27, and those with high SES did 1.29. Females with high SES showed 0.85 and those with low SES 0.67. None of the TABP-social control associations among the strata showed confidence intervals not including unity. In multiple logistic regression by native place, for those with rural origin the only term showed a statistically significance was the social control-SES of parents interaction, OR 3.99 (95% confidence interval, $1.03{\sim}15.46$). For those of urban origin, none of the terms are statistically significant. These results suggest a social upward mobility by education of the rural disadvantaged group and a Confucian idea that regards academic achievement as one of social virtues, both of which may reflect the different sociocultural structures from the West.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.2
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• pp.94-101
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• 1989

Transport properties of 2DEG at AlGaAs/GaAs interface such as average electron energy, flight distance, each valley occupancy ratio, average electron velocity for various fields are investigated by MONTE-CARLO method. As the electric field increases, more electrons transit drastically from (000) valley to (000) upper valley. This phenomenon shows the nonstationary effect such as velocity overshoot. The duration of the transient decreases from about 1.4 psec for electric field E = 7KV/cm to about 0.7 psec for 12KV/cm. The average electron velocity during transient transport in 2DEG is about 8 times the steady-state velocity for E = 12KV/cm at room temperature. In comparison with bulk GaAs the peak velocity in the 2DEG is higher than that in even pure bulk GaAs at electric field E = 7 KV/cm. On the basis of the fact that the electrons in the 2DEG have larger peak velocity and shorter transient time of velocity than those in the bulk GaAs, it is suggested that the device with 2DEG may obtain higher mobility than that with bulk GaAs.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.372-382
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• 1996

In order to elucidate the relationship between the mobility of heavy metals in soil and their uptake by plants, the soil samples collected from the Mangyeong River area were analyzed for the contents and existing forms of the heavy metals and the correlation between the contents of heavy metals in the soil and those in various parts of rice plants therefrom. The soil samples were collectes from ten sites in the paddy fields in 1982 and 1990, respectively, and the analysis on heavy metals including Cd, Zn, Cu and Pb was performed. The results are as follows: Total contents of heavy metals in the samples of 1990 were higher than those of 1982. The extent of increase was that Cd, Zn, Cu and Pb were 3, 29, 59 and 8% in top soil and 8, 50, 91 and 8% in sub-soil, respectively. The order of increasing ratio was Cu > Zn > Pb > Cd and the variation of Cd content by sequentially different extraction was organically bound > dilute acid-extractable=Fe-Mn oxide bound > exchangeable > residual fractions and the content of Cd with organically bound was $46.62{\sim}48.08$ and $41.18{\sim}50.18%$ of total Cd in top and sub-soil, respectively. The ratios of immobile heavy metals, Cd, Pb, Cu and Zn, bound within an oxide or silicate matrix of Fe-Mn oxide in top-soil were 21.25, 35.98, 74.18 and 82.12%, respectively, and consequently their mobile ratios of exchangeable, dilute acid-extractable and organically bound were more than 17.88%. Those of mobile Cd, Pb, Cu and Zn were 78.25, 64.02, 25.82 and 17.88%, respectively. Except for Pb a correlation between the contents of Cd, Zn, and Cu of exchangeable and dilute acid-extractable in top-soil and those in leaf blade, stem and panicle axis was significant, but was not significant in sub-soil.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.6
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• pp.1-6
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• 2011

A transparent oxide thin film transistors (Transparent Oxide-TFT) have been fabricated by RF magnetron sputtering at room temperature using amorphous indium zinc oxide (a-IZO) as both of active channel and source/drain, gate electrodes and co-sputtered $HfO_2-Al_2O_3$ (HfAIO) as gate dielectric. In spite of its high dielectric constant > 20), $HfO_2$ has some drawbacks including high leakage current and rough surface morphologies originated from small energy band gap (5.31eV) and microcrystalline structure. In this work, the incorporation of $Al_2O_3$ into $HfO_2$ was obtained by co-sputtering of $HfO_2$ and $Al_2O_3$ without any intentional substrate heating and its structural and electrical properties were investigated by x-ray diffraction (XRD), atomic force microscopy (AFM) and spectroscopic ellipsometer (SE) analyses. The XRD studies confirmed that the microcrystalline structures of $HfO_2$ were transformed to amorphous structures of HfAIO. By AFM analysis, HfAIO films (0.490nm) were considerably smoother than $HfO_2$ films (2.979nm) due to their amorphous structure. The energy band gap ($E_g$) deduced by spectroscopic ellipsometer was increased from 5.17eV ($HfO_2$) to 5.42eV (HfAIO). The electrical performances of TFTs which are made of well-controlled active/electrode IZO materials and co-sputtered HfAIO dielectric material, exhibited a field effect mobility of more than $10cm^2/V{\cdot}s$, a threshold voltage of ~2 V, an $I_{on/off}$ ratio of > $10^5$, and a max on-current of > 2 mA.

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.734-744
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• 2011

A soil stabilization method is an effective and practical remediation alternative for arsenic (As) and heavy metal contaminated farmland soils nearby abandoned metal mine in Korea. This method is a technique whereby amendments are incorporated and mixed with a contaminated soil. Toxic metal bind to the amendments, which reduce their mobility in soil, so the successful stabilization of multi-element contaminated soil depends on the combination of critical elements in the soil and the type of amendments. The objective of this study is to investigate the treatment effects and applicability of limestone (LS) and steel refining slag (SRS) as the amendment for farmland soil contaminated with As and heavy metals, and a lab-column test was conducted for achieving this purpose. The result showed that soil treated with LS and SRS maintained pH buffer capacity and, as a result, the heavy metal leaching concentration was quite low below the water quality standard compared to untreated soil which leachate exceeding the water quality standard was observed, however, the arsenic concentration rather increased with increasing mixture ratio of SRS. This was believed to be related to phosphorus (P) contained in SRS, and dominancy in the competitive adsorption relation between As and P binding strongly to iron might be different according to soil characteristic. We suggested that LS is a effective amendment for reducing heavy metals in soil, and SRS should be used after investigating its applicability based on the adsorption selectivity of arsenic and phosphorus in selected soil.

• Journal of Korea Entertainment Industry Association
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• v.14 no.7
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• pp.529-538
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• 2020

This study aims to develop of contents for the activities of daily living training - Korean version that reflexes the domestic situation and can be applied to clinical practice. For contents development, a Delphi survey was conducted with 13 experts. In the first Delphi survey, 133 items of activities of daily living training are derived based on previous studies, and then the extracted items are asked to group of experts, and the derived items are answered for actual domestic clinical application. In the second survey, 118 items were added by excluding items with a low content validity ratio (CVR) including the results of the first survey, and adding items that can be derived from other opinions. In the 3rd survey, while presenting the 2nd Delphi survey items as they are, it provides an opportunity to change their opinions by presenting their 2nd response and the 2nd average score of other expert panels, and adding appropriateness and importance together. The data were analyzed to obtain the mean, standard deviation, interquartile range, CVR, convergence, and consensus. Finally, a total of 69 items were selected and 49 items were excluded so that 105 items for CVR 0.54 or higher, 111 items for convergence degree 0.50 or lower, and 70 items for continuity degree 0.75 or higher. Sexual activity, care of others, care of pets, and child rearing are difficult to apply socially and culturally, driving and community mobility cannot be performed within the clinical room, and home establishment and management may have different roles depending on gender, and religious spiritual activities and expression are so personal. For these reasons, these items were found to have low importance or suitability. This study can be usefully used as an indicator on the activities of daily living training - Korean version in clinic or community setting.