• Journal of Educational Research in Mathematics
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• v.17 no.4
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• pp.453-475
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• 2007

School algebra starts with introducing algebraic expressions which have been one of the cognitive obstacles to the students in the transfer from arithmetic to algebra. In the recent studies on the teaching school algebra, algebraic thinking is getting much more attention together with algebraic expressions. In this paper, we examined the processes of the transfer from arithmetic to algebra and ways for teaching early algebra through algebraic thinking factors. Issues about algebraic thinking have continued since 1980's. But the theoretic foundations for algebraic thinking have not been founded in the previous studies. In this paper, we analyzed the algebraic thinking in school algebra from historico-genetic, epistemological, and symbolic-linguistic points of view, and identified algebraic thinking factors, i.e. the principle of permanence of formal laws, the concept of variable, quantitative reasoning, algebraic interpretation - constructing algebraic expressions, trans formational reasoning - changing algebraic expressions, operational senses - operating algebraic expressions, substitution, etc. We also identified these algebraic thinking factors through analyzing mathematics textbooks of elementary and middle school, and showed the middle school students' low achievement relating to these factors through the algebraic thinking ability test. Based upon these analyses, we argued that the readiness for algebra learning should be made through the processes including algebraic thinking factors in the elementary school and that the transfer from arithmetic to algebra should be accomplished naturally through the pre-algebra course. And we searched for alternative ways to improve algebra curriculums, emphasizing algebraic thinking factors. In summary, we identified the problems of school algebra relating to the transfer from arithmetic to algebra with the problem of teaching algebraic thinking and analyzed the algebraic thinking factors of school algebra, and searched for alternative ways for improving the transfer from arithmetic to algebra and the teaching of early algebra.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.1
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• pp.23-32
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• 2008

According to recent frequent local flash flood due to climate change, the very short-term rainfall forecast using remotely sensed rainfall like radar is necessary to establish. This research is to evaluate the feasibility of GIS-based distributed model coupled with radar rainfall, which can express temporal and spatial distribution, for multipurpose dam operation during flood season. $Vflo^{TM}$ model was used as physically based distributed hydrologic model. The study area was Yongdam dam basin ($930\;km^2$) and the 3 storm events of local convective rainfall in August 2005, and the typhoon.Ewiniar.and.Bilis.collected from Jindo radar was adopted for runoff simulation. Distributed rainfall consistent with hydrologic model grid resolution was generated by using K-RainVieux, pre-processor program for radar rainfall. The local bias correction for original radar rainfall shows reasonable results of which the percent error from the gauge observation is less than 2% and the bias value is $0.886{\sim}0.908$. The parameters for the $Vflo^{TM}$ were estimated from basic GIS data such as DEM, land cover and soil map. As a result of the 3 events of multiple peak hydrographs, the bias of total accumulated runoff and peak flow is less than 20%, which can provide a reasonable base for building operational real-time short-term rainfall-runoff forecast system.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.9
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• pp.830-837
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• 2015

Space debris has been a major issue recently for the space-active nations because its growing population is expected to increase the collision risk with operational satellites. Radar and electro-optical system has been used for space debris surveillance, which may cause unnecessary anti-collision manoeuvers due to their low tracking accuracy. So an additional tracking system is required to improve the predicted orbit accuracy and then to jude the anti-collision maneouvers more efficiently. The laser tracking system has been considered as an alternative to decrease these unnecessary manoeuvers. Korea Astronomy and Space Science Institute has been developing a space object laser tracking system which is capable of laser tracking for satellites with retro-reflectors and for space debris using high power laser, and satellite imaging using adaptive optics. In this study, the tracking capability is analyzed for space debris using high power laser based on link budget, false alarm probability and signal detection probability.

• Journal of Broadcast Engineering
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• v.20 no.4
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• pp.509-520
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• 2015

A design for the merge mode of three dimensional High Efficiency Video Coding (3D-HEVC) is proposed in this paper. The proposed design can reduce the implementation complexity by removing the duplicated modules of the HEVC. For the extension codec, the implementation complexity is as crucial as coding efficiency, meaning if possible, extension codec needs to be easily implemented through by reusing the design of the legacy codec as-is. However, the existing merging process of 3D-HEVC had been built-in integrated in the inside of the HEVC merging process. Thus the duplicated merging process of HEVC had to be fully re-implemented in the 3D-HEVC. Consequently the implementation complexity of the extension codec was very high. The proposed 3D-HEVC merge mode is divided into following two stages; the process to reuse the HEVC modules without any modification; and the reprocessing process for newly added and modified merging modules in 3D-HEVC. By applying the proposed method, the re-implemented HEVC modules, which accounted for 51.4% of 3D-HEVC merge mode confirmed through the operational analysis of algorithm, can be eliminated, while maintaining the same coding efficiency and computational complexity.

• Journal of Environmental Impact Assessment
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• v.27 no.3
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• pp.322-333
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• 2018

This study was carried out to measure atmospheric environmental improvement effect and estimate its social benefit of thermal power plants through Environmental Impact Assessment (EIA) for quantitative analysis about operational performances of EIA. In this study, 'EIA outcome' is defined as whether or not the system is implemented, therefore, environmental standard to be followed by each project and consultation contents were compared. In total 60 cases of thermal power plant construction projects that have been consulted over the past 10 years since 2010, major air pollutants have been significantly reduced after the implementation of EIA. The $PM_{10}$ reduced annual 3,745 tons, $NO_2$ by 74,569 tons, and $SO_2$ by 37,647 tons, which were estimated at approximately 240 billion won~5 trillion 967 billion won per year for social benefit. This means the total cost of power plant operations will be cut to 7 trillion 192 billion won~178 trillion 994 billion won over a 30-year period. The reduced amount of air pollutants emitted by energy generation facilities across the country is worth 50%, and its economic value is larger than the annual Current Health Expenditure in Korea. This is meant by the fact that all projects are subject to uniform criteria under the existing relevant regulation, but that each project plans are optimized according to the characteristics of target areas and projects through the process of EIA.

• Science of Emotion and Sensibility
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• v.20 no.1
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• pp.31-40
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• 2017

The present study used one of research techniques which is eye gaze tracking for neuromarketing. When pupil's size of men dilated over than three sigma (0.135%), the interest and eye movement in observation were measured. According to statistical analysis of previous studies, three sigma range is meaningful therefore sigma range was used as operational definition because 'pupil dilatation' is difficult to be define in eye gaze tracking data. Pictures of basketball games were selected as visual stimuli and 90% effective ratio of total 7,200 data were calculated. Thus, 29 of 34 participants were used for test. Pupil's size was calculated by applying pupil's width and height into a formular; [Pupil's size = Pupil width/2${\times}$Pupil height/$2{\times}{\pi}$]. In conclusion, billboard utilized for sports marketing had meaningless effects because gaze frequency to basketball player and surrounding environment was higher than that to billboard when participantsas game spectators diltaed their pupil's size over than three sigma. Thus, it was required using new marketing strategies like neuromarketing to increase utility through the present study.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.2
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• pp.96-104
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• 2001

Usage of ecosystem models has been extended to landscape scales for understanding the effects of environmental factors on natural and agro-ecosystems and for serving as their management decision tools. Accurate prediction of spatial variation in daily temperature is required for most ecosystem models to be applied to landscape scales. There are relatively few empirical evaluations of landscape-scale temperature prediction techniques in mountainous terrain such as Korean Peninsula. We derived a periodic function of seasonal lapse rate fluctuation from analysis of elevation effects on daily temperatures. Observed daily maximum and minimum temperature data at 63 standard stations in 1999 were regressed to the latitude, longitude, distance from the nearest coastline and altitude of the stations, and the optimum models with $r^2$ of 0.65 and above were selected. Partial regression coefficients for the altitude variable were plotted against day of year, and a numerical formula was determined for simulating the seasonal trend of daily lapse rate, i.e., partial regression coefficients. The formula in conjunction with an inverse distance weighted interpolation scheme was applied to predict daily temperatures at 267 sites, where observation data are available, on randomly selected dates for winter, spring and summer in 2000. The estimation errors were smaller and more consistent than the inverse distance weighting plus mean annual lapse rate scheme. We conclude that this method is simple and accurate enough to be used as an operational temperature interpolation scheme at landscape scale in Korea and should be applicable to elsewhere.

• Korean Journal of Food Science and Technology
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• v.30 no.1
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• pp.110-117
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• 1998

A packed-bed reactor with immobilized transglucosidase (TG) was operated to test the possibility of continuous production of isomaltooligosaccharides (IMO) and the effect of concentration and feed rate of substrate solution on the production pattern as well as operational stability The pattern of formation of IMO was the same to the one of soluble TG. The concentrations of glucose and isomaltose produced by the packed-bed reactor were gradually decreased as the flow rates were increased regardless of the concentrations and kinds of maltose solution as substrate. Isomaltotriose showed the same tendency except 10% maltose solution. But the concentration of panose was increased and then decreased as the flow rates were increased. The maximum yield of IMO was 52.1% when 10% (w/v) solution was fed to the reactor at 2 mL./min feed rate. When each 20% and 30% (w/v) solution was respectively used at $0.5{\sim}1.0\;mL/min$, the maximum yield were $39.0{\sim}38.0%\;and\;12.1{\sim}14.2%$. The maximum yield was 36.3% at $0.5{\sim}1.0\;mL/min$ when a commercial maltose product containing 20% maltose was used. The reactor was stably operated at $55^{\circ}C$. 85% and 65% of initial activity was maintained for 144 hours and 288 hours of operation, respectively. A reactor analysis strongly an immobilized TG system could apply to continuous production of IMO.

• The Journal of the Korea Contents Association
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• v.15 no.3
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• pp.101-113
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• 2015

This study aims to prepare countermeasures to prevent and minimize drowning accident in inland waters by examining the current status of inland water safety management in Korea and diagnosing the defects. The defects in current inland water safety management is analyzed in four aspects. First is the legal defect that includes the absence of legislation that directs the inland water safety management. Second is the instructional defect such as the absence of educational program for prevention of inland water accidents and lack of professional water rescue experts. Third is cooperation defect such as dispersed reporting system and lack of private-public partnership in accident response. Fourth is the defect of emergency response ability, professionalism and accident response skills due to the dispersion and overlaps of safety management systems. In order to improve these defects, this study finds the countermeasures based on the survey of water sports professions and users and its analysis as follows: legislation of '(tentatively named) special act for water safety management in inland waters' is suggested in the legal aspects. A development of inland waters safety education program and training of water accident experts are suggested in the instructional aspects. Integrated operational system for water accident management, activation of safety network and re-establishment of private-public partnership are suggested in the cooperation aspects. Systematic and efficient inland water safety management plans such as enhancement of accident response skills and expertise and integrated inland water safety management with fire department-centered system were suggested in the aspects of emergency response ability.

• Journal of the Korean Geosynthetics Society
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• v.9 no.3
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• pp.77-85
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• 2010

The change of water level in reservoirs is an important factor causing failure of bank slopes, i.e. landslide. The water level of Three Gorges reservoir in China fluctuate between 145 m and 175 m, as a matter of flood control. During its normal operational state, the rate of water level fluctuation is supposed to range from 0.67 m/d to 3.0 m/d. Majiagou slope is located on the left bank of Zhaxi River, 2.1 km up from the outlet. Zhaxi River is a tributary of the Yangtze River within the Three Gorges area, of which the water level changes with the reservoir. At the back of Majiagou slope, a 20 m long and 3~10 cm wide fissure developed just after the reservoir water level rose from 95 m to 135 m in 2003. This big fissure was a full suggestion of potential failure of this slope. In this study, unsaturated-saturated seepage analyses were carried out to simulate the change of pore-water pressures in the bank slope subjected to the reservoir water level change. The obtained pore-water pressures were then used to evaluate the change in factor of safety (FS) with reservoir water level. It was found that the phreatic line showed a delayed response with respect to the change of the reservoir water level, because the seepage through soil layer was generally slower than water flows itself. During the rising and drawdown process, the phreatic lines take the shapes of concave and convex, respectively. And the fluctuation of reservoir water level just affected the front part of the bank slope, but had little influence on the back of the slope.