• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.4 no.4
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• pp.201-208
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• 2000

The reduction of NO by hydrocarbons was investigated over Cu/Al$_2$O$_3$catalysts using a stainless steel flow reactor under highly oxidising diesel exhaust conditions(up to 15%). Three different Cu loadings(1,5 and 10wt.%) on an $Al_2$O$_3$support were prepared and characterized using spectroscopic techniques. The catalytic activity tests show that different Cu loadings as well as temperature, oxygen, and hydrocarbon concentration levels significantly influence the NO reduction. Increasing Cu loadings up to 5 and 10wt.% decreases the catalytic activities for NO reduction due to the formation of a bulk crystalline CuO phase, as observed from XRD and SEM images. In particular, the visualization of the copper dispersion on the surface using the SEM-BEI technique provides information on the extent of copper saturation, particle size, and the effects on NO reduction. However, the lower Cu loading(1 wt.%) increases the catalytic activity with a temperature window of 720-810K, thereby favoring the formation of well dispersed isolated Cu species, e.g. Cu(sup)2+ ions, which is related to selective NO reduction. The effects of other reaction parameters, such as oxygen, the hydrocarbon level and type, and byproduct emissions are further discussed.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.675-682
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• 2016

Sudden voltage drops and outages frequently disturb the operation of sensitive loads for domestic, commercial, and industrial use. In some cases, these events may even impair the functioning of relevant equipment. To maintain power under such conditions, a UPS system is usually installed. Once a disturbance happens at the grid side, the line-interactive UPS system takes over the load to prevent an interruption. But, due to magnetic saturation of the transformer, a significant inrush current may occur for the transformer-coupled loads during this transition. The generation of such transient currents may in turn decrease the line voltage and activates over-current protecting devices of the system. In this work, a cost-effective, line-interactive UPS system is proposed that eliminates the inrush current phenomenon associated with transformer-coupled loads. The strategy was implemented by connecting a standard current-regulated voltage source inverter (CRVSI) to the secondary winding of the load transformer. During any transient condition at the grid side, the load current is monitored and regulated to achieve either seamless compensation of the load current or complete transferal of load from grid to the inverter. Experimental results were obtained for a prototype under all possible operating conditions so as to validate the performance of the proposed topology.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.42 no.1
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• pp.25-32
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• 2005

In this paper, it is attempted to provide a unified explanation for typical short channel GaAs MESFET’s and SOI-structured Si JFET's behaviors such as: i) drain voltage-induced threshold voltage roll-off, ii) finite output ac resistance beyond the saturation, and iii) weak dependence of the drain saturation current on the channel length. Replacing the conventional GCA with a new assumption that is suggested in order to include the longitudinal field variation, and taking into account the channel current continuity and the field-dependent mobility, we can derive the two-dimensional potential in both depletion region and undepleted conducting channel. Obtained expressions for the threshold voltage and the drain current will be considerably accurate over the entire operating region. Moreover, in comparison with the conventional channel length shortening models, our model seems to be more reasonable in explaining the Early effect.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.157-165
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• 2016

Among high-tech products, the mobile phone has experienced a rapid rate of innovation and a shortening of its product life cycle. The shortened product life cycle poses major challenges to those involved in the creation of forecasting methods fundamental to strategic management and planning systems. This study examined whether the best model applies to the entire diffusion life span of a mobile phone. Mobile phone sales data from a specific mobile service provider in Korea from March of 2013 to August of 2014 were analyzed to compare the performance of two S-shaped diffusion models and two non-linear regression models, the Gompertz, logistic, Michaelis-Menten, and logarithmic models. The experimental results indicated that the logistic model outperforms the other three models over the fitted region of the diffusion. For forecasting, the logistic model outperformed the Gompertz model for the period prior to diffusion saturation, whereas the Gompertz model was superior after saturation approaches. This analysis may help those estimate the potential mobile phone market size and perform inventory and order management of mobile phones.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.18-25
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• 2016

Enhanced tubes are used widely in the evaporators of large tonnage compression-type refrigerators. The evaporators consist of tube bundles, and the refrigerant properties are dependent on the locations in the tube bundles. In particular, the saturation temperatures of low pressure refrigerants (R-11, R-123) are strongly dependent on the locations due to the saturation temperature-pressure curve characteristics. Therefore, for the proper design of evaporators, local property predictions of the refrigerants are necessary. In this study, a computer program that simulates the flooded refrigerant evaporators was developed. The program incorporated theoretical models to predict the refrigerant shell-side boiling heat transfer coefficients and pressure drops across the tube bundle. The program adopted an incremental iterative procedure to perform row-by-row calculations over the specified incremental tube lengths for each water-side pass. The program was used to simulate the flooded refrigerant evaporator of the "T" company operating with R-123, which yielded satisfactory results. The program was extended to predict the performance of the flooded refrigerant evaporator operating with R-11, R-123, and R-134a. The effects of bundle aspect ratio are investigated.

• Journal of Korean Society of Transportation
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• v.20 no.3
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• pp.31-39
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• 2002

The primary objective of this study is to develop a reliable method for estimating the left turn capacity at the signalized intersection. This study is performed during periods of congestion. Multi left turn lane(bay lane and exclusive lane) approaches are examined. When more than one left turn lane exists, traffic volumes are not distributed equally over each lane. The fundamental approach taken in this study is measuring headways on left turn lanes with altering the bay length from 20m to 120m. Left turn lane is divided into 3 sub-sections in this study. These are SLP section(start-up lost time Period), SFP section(saturation flow period), LSP section(lane selection period). Saturation flow rates are evaluated for each sub section periods. As a results of analysis, it has been confirmed that the left turn capacity can be estimated by left turn bay length and effective green time for left turn. The left turn bay length adjustment factor is suggested in this study.

• CELLMED
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• v.5 no.1
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• pp.4.1-4.4
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• 2015

Yoga is an ancient Indian system of life, encompassing various practices including practices for self-discipline and also for regulating the health states of the individual, being practiced for thousands of years. The present study aims at understanding the effect of two high frequency breathing practices over autonomic nervous system. Forty healthy male volunteers of age $21{\pm}2$ years with $9{\pm}3$ months of Yoga practice experience were recruited. The two high frequency Yoga breathing practices, kapalabhati (KB) and bhastrika (BH) were given as interventions randomly on either of the two days to minimise laboratory bias. They were assessed before and immediately after the interventions for heart rate, respiratory rate, heart rate variability (HRV), blood pressure and peripheral oxygen saturation. There was a significant increase in heart rate (p<0.01; p<0.001), systolic blood pressure (p<0.01; p<0.001), NN50 (p<0.01; p<0.001) component of HRV for both KB and BH groups respectively. There was a significant reduction in respiratory rate in both the groups (p<0.001, and p<0.05, BH and KB respectively) immediately following intervention. A significant increase in LF component of HRV and reduction in Diastolic blood pressure and high frequency (HF)component following KB was also observed (p<0.05, for all comparisons). The Mean peripheral oxygen saturation remained unaltered in both the groups (p>0.05).The results suggest that high frequency yoga breathing practices induce physiological arousal immediately as evidenced by increased blood pressure and heart rate. The sympathetic arousal was more following KB session as evidenced by an increased diastolic blood pressure, LF power and a decrease in HF power of HRV as compared to the BH session.

• International Journal of Advanced Culture Technology
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• v.8 no.3
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• pp.123-132
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• 2020

In contemporary times, there is an increasing demand for a dedicated healthcare environment, all over the world. The main motivation for this demand is the level of awareness manifested by the users and reflected on their expectations. Therefore new research strategies and design actions are investigated in order to answer to the users' needs and to provide objective design tools for the specialist. This study continues a series of previous developments of the Healthcare Environment Color Index that should be used for public facilities in Korea and abroad. The cross-cultural approach is a new opportunity for exchanging know-how and for testing and calibrating the perception of the users on the color index. The gathering of results was made based on the online survey provided in this phase in English version for the Romanian users. The survey was intended as an objective mean of research and an efficient way of disseminating information on the subject thus contributing to increasing the level of awareness of the users. A total of 86 Romanian and 89 Koreans with valid answers took part in the survey. Comparative visualizations of the results showed significant similarities concerning the patterns of color preferences but also cultural and emotional differences. As a result both categories of users proved to be aware of the relation between healthcare environment color and its effects on health. They also showed a common understanding on the potential of the color index. As a result the most appealing colors to be applied to the healthcare environment were the series G and B, and the most effective ones were proved to be the ranges of high lightness and low saturation but also the medium high lightness and medium saturation. Both the similarities and the differences of choice between Romanians and Koreans show that cultural and emotional differences of color recognition are important and that should be taken into consideration in design, in order to generate an inclusive and efficient healthcare environment.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.4
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• pp.260-266
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• 2012

Purpose: The purpose of this study is to identify the changes of a physiologic nature and the sedative parameters associated with dexmedetomidine and pethidine, in patients undergoing plate and screw removal surgery, after orthognathic surgery. Methods: Twenty-three patients were sedated with dexmedetomidine and pethidine during plate and screw removal, after orthognathic surgery. An initial loading dose of dexmedetomidine ($1.0{\mu}g/kg$ infused over 10 minutes) was followed by a maintenance dose ($1.0{\mu}g/kg/hr$). Systolic blood pressure, diastolic blood pressure, mean arterial pressure, oxygen saturation, and heart rate were monitored. Perioperative amnesia and anxiety were recorded. Results: Significant changes were found in the blood pressure and heart rate (Freidman test, P<0.05), but not in oxygen saturation (Freidman test, P>0.05). Amnesia during local injection was observed in eight patients (34.8%). Compared with the preoperative anxiety score, the intraoperative anxiety score was decreased. Conclusion: In this study, we found cardiovascular and respiratory stability in intravenous sedation using dexmedetomidine with pethidine, in plate and screw removal, after orthognathic surgery. Furthemore, intravenous sedation using dexmedetomidine with pethidine shows adequate analgesic and sedative effects.

• Journal of Korean Academy of Nursing
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• v.30 no.1
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• pp.171-182
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• 2000

This study was performed to investigate the effect of kangaroo care on body weight, physiological responses and behavioral states in premature infants. The subjects were 32 premature infants, fifteen for the kangaroo care group and seventeen for the control group, who hospitalized in a neonatal intensive care unit at a university-affiliated hospital. The kangaroo care was applied 8 times during the twenty five days with 40 minutes for each session. The kangaroo care provides the skin-to-skin contact during which a premature infant wearing a diaper and a hat is placed on its mother's chest. As for the measures, body weight was measured everyday. The levels of epinephrine, norepinephrine and 17-OHCS were measured twice, before beginning the first intervention and after finishing the last intervention. While each session of the care is undergoing, such physiological responses were measured periodically as heart rate, respiration rate, oxygen saturation, core temperature and skin temperature. The results were as follows : 1. The weight gain was significantly greater in the kangaroo care group than that in the control group during the period of performing the kangaroo care. 2. No significant difference was revealed between the two groups in heart rate, respiration rate, oxygen saturation and core temperature. The kangaroo care group also showed significant increases in the skin temperature. 3. The differences in the levels of epinephrine, norepinephrine and 17-OHCS were not significant between the kangaroo care and the control groups. The level of norepinephrine in the two groups was significantly increased over time. 4. Sleep pattern changed significantly in the kangaroo group from a very restless sleep to a very quiet sleep. These results suggest that kangaroo care is an effective nursing intervention for premature infants in gaining weight, achieving stable physiological responses and facilitating a quiet sleep.