• Environmental Engineering Research
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• v.11 no.4
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• pp.208-216
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• 2006

In order to create a single flocculant/dual flocculation system, polyacrylamide-co-trimethyl ammonium ethyl acrylate chloride (TAEAC) polymers with varying molecular weights and structures were prepared for use of flocculants. The higher the cationic density of the polymer is higher, the higher was the conversion rate and the ratio of monomer. An acrylamide as nonionic monomer was less reactive than a TAEAC as cationic monomer. The branched polymer which was polymerized with a cross-linking agent, N, N-methylene bis-acrylamide had a higher stability and higher viscosity than a linear polymer but its dewatering efficiency was poor in a single flocculation system. In the case of single flocculant/dual flocculation, the branched polymer has better flocculation efficiency and the water content of the dewatered cakes was lower than the others, as the result of a re-flocculation effect. The optimum conditions for dual flocculation are a sequence in which the $1^{st}$ and $2^{nd}$ dosage are 75% and 25%/total dosage of a single flocculation system. The dewatering efficiency of a dual flocculation system is improved considerably from 10 to 25% under the experimental conditions used herein.

• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.4
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• pp.906-914
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• 1996

Due to the various reason, sealing of pit & fissure might be imperfect. One of these reason can be the fracture of sealant material because of the low hardness value of sealing material. The purpose of this in vitro study was to evaluate the microhardness of two different curing type pit and fissure sealants: Dual-cure and Light-cure. The result from the present study can be summarized as follows: 1. All pit and fissure sealants that used in this study showed statistically significant difference in their microhardness of upper and lower surface. (P <0.05) 2. Except of lower surface of teethmate, microhardness of 40-second curing sealant was statistically higher than that of 20-second curing sealant. (P <0.05) 3. In comparison of sealants, microhardness of dual-cure sealant was statistically higher than that of light-cure sealant. Above results suggest that the use of dual-cure sealant and longer curing time are recommended.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.1
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• pp.60-67
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• 2002

In this paper, the dual band VCO of mobile communication terminal using oscillation part switching circuit is proposed. In order to model the VCO accurately, the resonator is converted the equivalent circuit which is analyzed to use numerical method and designed optimal the dual band VCO operating GSM and DCS band. In order to demonstrate the objective theory of the proposed VCO, the dual band VCO is designed and experimented. The results of experiment, it is conformed that the VCO can be used mobile communication hand phone and components of three generation mobile communication systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.5
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• pp.2063-2081
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• 2018

A resource allocation algorithm is proposed in this paper to simultaneously minimize the total system power consumption and maximize the system throughput for the downlink of multi-user multiple input multiple output-orthogonal frequency division multiplexing (MIMO-OFDM) systems. With the Lagrange dual decomposition method, we transform the original problem to its convex dual problem and prove that the duality gap between the two problems is zero, which means the optimal solution of the original problem can be obtained by solving its dual problem. Then, we use convex optimization method to solve the dual problem and utilize bisection method to obtain the optimal dual variable. The numerical results show that the proposed algorithm is superior to traditional single-objective optimization method in both the system throughput and the system energy consumption.

• Journal of the Korean Society of Costume
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• v.50 no.7
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• pp.5-14
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• 2000

Fashion leadership of middle- and high-school male student was measured. The subjects were divided into five subgroups including, fashion dual leaders(13.3%), innovators(10.3%), opinion leaders(7.6%), followers(52.3%), and laggards(16.3%), according to their innovativeness and opinion leadership. The findings were as follows : fashion dual leaders were very confident and fashion-conscious while other subgroups were very price-conscious and quality-aware. Among the fashion information sources included in the study' my own experience and opinion' was the most Important to all 5 subgroups. Generally the higher the fashion leadership was, the more actively utilized fashion information sources. The fashion magazine and commercials as information sources was not as important to the subjects as it was to college women. Apparel shopping behavior was also significantly different among subgroups. As a whole, the general characteristics, such as. the use of fashion information and the apparel shopping behavior, of opinion leaders and innovators were similar, but those of followers and laggards were very dissimilar.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.69-74
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• 2017

Due to the advantage of communication coverage extension and removement of shadowing area, relay can be applied in various wireless communication systems. In this paper, we analyze performance of downlink with dual-hop communication systems which use a relay in railway environments. We adopted asymmetric communication system which use coherent modulation scheme in base station-relay link and differential modulation scheme in relay-destination link. The performance of communication system is analyzed using symbol error rate, and performance comparison with the systems which adopts fully coherent scheme is studied. We also investigate the performance of system depending on relay distance and energy allocation.

• Journal of Family Resource Management and Policy Review
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• v.24 no.3
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• pp.19-33
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• 2020

The purpose of this study was to investigate whether paid work time desynchronization affected housework time desynchronization. Time slot data from the Korean Time Use Survey data from 2014 was analyzed. This study included 1,475 married couples aged 20 to 59. They were dual-earner couples, heterosexual couples, and both partners worked during the day, either durong the week or on the weekend. The data was analyzed by the following four groups: weekday-husband, weekday-wife, and weekend-husband, weekend-wife. The results demonstrated that as the desynchronization of paid work increased, the desynchronization of time spent on housework in the weekday-husband and weekend-husband groups also increased. Second, the amount of leisure time did not affect the desynchronization of time spent on housework. Lastly, the amount of time that one person spent on housework increased the housework time desynchronization level. In addition, if the family had children who attended primary, middle, or high school-mothers in the weekday-wife group completed more housework. These results demonstrated that paid work time desynchronization might be a way to decrease the amount of time that dual-earner wives' spent housework.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.166-166
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• 2020

Recently, As the frequency of localized heavy rains increases, the use of high-resolution radar data is increasing. The produced radar rainfall has still gaps of spatial and temporal compared to gauge observation rainfall, and in many studies, various statistical techniques are performed for correct rainfall. In this study, the precipitation correction of the S-band Dual Polarization radar in use in the flood forecast was performed using the ConvAE algorithm, one of the Convolutional Neural Network. The ConvAE model was trained based on radar data sets having a 10-min temporal resolution: radar rainfall data, gauge rainfall data for 790minutes(July 2017 in Cheongju flood event). As a result of the validation of corrected radar rainfall were reduced gaps compared to gauge rainfall and the spatial correction was also performed. Therefore, it is judged that the corrected radar rainfall using ConvAE will increase the reliability of the gridded rainfall data used in various physically-based distributed hydrodynamic models.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.805-807
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• 2004

Dual Mode technology has been developed as a new technology that allows to use a self-emissive display under full sunlight conditions. The new technology connects a LCD-like remissive operation mode in sunlight to an OLED-like self-emissive operation in the dark In the recent years, the focus of development has shifted towards the possibility of full colour operation.

• 연구논문집
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• s.28
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• pp.137-143
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• 1998

In the case of a boiler, scale is made in the tube by the chemical reactions of Ca and Mg ions contained in the water, and heat transfer rate is reduced because of increasement of heat resistance in the pipe of the heat flow. Thus it brings to reduce the energy efficiency and to make environmental pollution by the use of chemicals for the prevention and removement of scale. In this paper, we discussed the design of electronic generator for dual ultrasonic transmitters and analyzed the effect of scale prevention by ultrasound.