• Ecology and Resilient Infrastructure
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• v.7 no.2
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• pp.83-89
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• 2020

This hydraulic study analyzed the scour effect at fixed downstream weirs based on the changes in the upstream bed slope. The study was performed using six different bed slopes, that is, 0%, 2%, 3%, 4%, 7%, and 10% at 0.117 ㎥/s in all cases. The scour depth, scour length, and scour volume were measured using a broadband laser scanner to quantitatively analyze the scour at the downstream weir. This study also examined the adequacy of the designed apron length by comparatively analyzing the results of the scour experiments and the apron length calculated using conventional design standard formulas. The analysis of the local scour effect at the downstream weir showed that scour length and scour depth increased as the bed slope became steeper. A comparison between the results of the scour experiment and that of the conventional design formulas showed that both formulas of the National Construction Research Institute and the Bligh were distributed within the allowable values when there was no upstream bed slope. However, as the bed slope upstream of the weir gradually increased, the scour lengths of the apron deviated slightly from the values obtained from the conventional design formulas.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.72-80
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• 2018

Whilst it is common to construct high-rise buildings and long-span structures in the construction and building industry, there might be a number of problems such as excessive re-bars arrangement, deterioration of concrete quality, unnecessary quantity take-off and so forth. As these types of buildings and structures are getting more popular, it is widespread to apply high-strength materials such as high-strength concrete and re-bars to sustain durability and stability. This research aims to investigate the effectiveness of the high-strength reinforcing bars on the underground parking in a rigid-frame structure. In this study, the reinforcing bars with different yield strength were applied to corroborate the usefulness and practicability of the high-strength re-bars on the underground parking in a rigid-frame structure. The test results show that the quantity of reinforcement bars is lowered, as the yield strength of the re-bars are grown in general. However, the quantity of reinforcement bars on the development and splice has a tendency to increase slightly. Despite of the increase of the development and splice, the total quantity of reinforcing bars was reduced since the increasing ration of the pure quantity is higher than the development and splice. Base on the test results, it would be possible to achieve the reduction of reinforcing bars arrangement and lowering the amount of work to be done during a construction phase. Moreover, the reduced amount of bar arrangement will make it possible to improve workability and constructability of reinforced concrete structures. Ultimately, we will be able to attain improved quality and efficiency of construction using reinforced concrete.

• The Journal of the Korea Contents Association
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• v.20 no.3
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• pp.584-599
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• 2020

This study aimed to explore goals and development process of Child·youth Friendly Cities certified by UNICEF Korea and to provide a research basis for promotion and development of Child·youth friendly cities in Korea. Researchers conducted in-depth interviews with experts in two cities designated as UNICEF Child·youth Friendly Cities in early days. The findings showed that in order to successfully build and maintain friendly cities for children and youth, active interest and efforts of local governors and government officials for promoting friendly cities and policy enforcement based on four principles of child rights were required as prerequisite. In relation to managing Child·youth friendly cities, two cities selected as cases of this study provided universal social welfare programs for children and youth and expanded after-school care services for local students. Moreover they tried to promote decision making and protect rights of children and youth by allowing them to participate in community programs. The important distinctions of these cities were that they established a department exclusively for children and youth and closely cooperated with experts in private sectors. However, participants agreed that there should be more comprehensive and multilateral approach for building Child·youth friendly cities, adoption of incentive system for certification of Child·youth friendly cities and more active promotion of the UNICEF project. In conclusion, the researchers proposed policy implications.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.75-80
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• 2019

Sales of the Korean clothing industry grew to 16.9 percent on-year in 2010, but the growth rate dropped to 3 percent from 2011 to 2016 and the overall market began to slump to 1.1.6 percent in 2017. The competitiveness of clothing companies is also a major sector in logistics capability, and the average logistics cost of domestic clothing companies is 8.3 percent of sales in 2011, higher than the average 8 percent of domestic industries, and 36.4 percent of the total storage cost in 2011, higher than the 28.8 percent share of the total storage cost of domestic companies. As domestic production conditions such as wage hikes and labor disputes worsened in the 1990s, production facilities were rapidly moved overseas, which led many clothing companies to have no production facilities or a minimal production base in Korea and focus on marketing and design capabilities. The total storage capacity and storage efficiency of the logistics center became very important as the products were changed to the form of mass warehousing and small-volume forwarding. Research shows that building column spacing, a model of this research, can affect the amount of hanger rack storage empirically, so for sustainable growth of clothing companies, it is necessary to improve competitiveness in the logistics market by reducing costs and improving efficiency to overcome difficulties in corporate management. Because logistics costs are 8.3 percent and operating profit to sales ratio is 2 percent, it is expected that operating profit will increase by 41.5 percent if logistics costs are reduced by 10 percent. If 10% of storage cost is saved based on storage cost, operating profit is expected to increase by 15% To strengthen the competitiveness of the clothing industry, a reduction in logistics costs is essential. Therefore, the purpose of this study is to provide hints that logistics experts can have empirically small amounts in reducing storage costs through column spacing adjustment of logistics centers that have not been dealt with statistically until now, and to contribute to the continued growth of clothing companies and the development of the domestic logistics industry.

• Clean Technology
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• v.18 no.3
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• pp.325-328
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• 2012

The condensation reaction of 9,9'-bis(4-hydroxyphenyl)fluorene with epichlorohydrin to prepare 9,9'-bis[4(glycidyloxy) phenyl]fluorene (2), an important building block for fluorene-containing epoxy polymers, has been studied. The reaction is found to be quite sensitive to several experimental conditions such as reaction temperature and time, added amount of epichlorohydrin, the presence of catalysts and the use of co-solvent. Several conditions for obtaining the best yield in the reaction are: the reaction temperature is below 373 K and the reaction time is shorter than 1.5 h, and the ammonium salts act as a catalyst. Also, the use of ternary solvent (toluene, DMSO, water) has been proved to be crucial to maintain the reaction temperature and for an easy purification. Thus, the reaction proceeds in an environment-friendly manner where the use of reactants and the production of chemical wastes is minimized.

• Management & Information Systems Review
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• v.33 no.1
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• pp.45-63
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• 2014

A trading system is a computer trading program that automatically submits trades to an exchange. Mechanical a trading system to execute trade is spreading in the stock market. However, a trading system to trade a single asset might occur instability of the profit because payoff of this system is determined a asset movement. Therefore, it is necessary to develop a trading system that is trade two assets such as a pair trading that is to sell overvalued assets and buy the undervalued ones. The aim of this study is to propose a relative value based trading system designed to yield stable and profitable profits regardless of market conditions. In fact, we propose a procedure for building a trading system that is based on the rough set analysis of indicators derived from a price ratio between two assets. KOSPI 200 index futures and S&P 500 index futures are used as a data for evaluation of the proposed trading system. We intend to examine the usefulness of this model through an empirical study.

• Journal of Korea Water Resources Association
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• v.48 no.5
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• pp.409-423
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• 2015

In this study the very short-term rainfall forecasting and storm water forecasting using the weather radar data were implemented in an urban stream basin. As forecasting time increasing, the very short-term rainfall forecasting results show that the correlation coefficient was decreased and the root mean square error was increased and then the forecasting model accuracy was decreased. However, as a result of the correlation coefficient up to 60-minute forecasting time is maintained 0.5 or higher was obtained. As a result of storm water forecasting in an urban area, the reduction in peak flow and outflow volume with increasing forecasting time occurs, the peak time was analyzed that relatively matched. In the application of storm water forecasting by radar rainfall forecast, the errors has occurred that we determined some of the external factors. In the future, we believed to be necessary to perform that the continuous algorithm improvement such as simulation of rapid generation and disappearance phenomenon by precipitation echo, the improvement of extreme rainfall forecasting in urban areas, and the rainfall-runoff model parameter optimizations. The results of this study, not only urban stream basin, but also we obtained the observed data, and expand the real-time flood alarm system over the ungaged basins. In addition, it is possible to take advantage of development of as multi-sensor based very short-term rainfall forecasting technology.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.25 no.4
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• pp.153-159
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• 2015

Inorganic pigments have been received a great attention for various applications including paint, glazed ceramic ink, art tile, and building exterior due to their excellent thermal and chemical stability. Traditionally, the compositions of $PbCrO_4$, CdS and CdSe have been widely used as a yellow inorganic pigment. However, the use of these compositions has been restricted in recent years, because they contain harmful elements such as Cd, Cr, Pb and Se. In this study, new environment-friendly ceria-based pigment was synthesized using solid state reaction. Crystal structure and morphology of the obtained $Ce_{1-x}Zr_xBi_yO_{2-y/2}$ yellow pigment were analyzed using XRD and SEM, respectively. Substitutional effect of Zr and Bi on the pigment color was analyzed using UV-vis. spectrophotometer and CIE $L^*a^*b^*$ analysis. The crystal structure of the obtained pigments was dependent on the calcination temperature. The color characteristics and absorption band of the pigments were dependent on the calcination temperature and Zr, Bi contents. As a result, all the obtained yellow pigments showed the effective absorption ranged from ultraviolet to visible light, and $Ce_{0.44}Zr_{0.36}Bi_{0.20}O_{0.19}$ (x = 0.36, y = 0.20) pigment showed the most brilliant yellow color.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.4
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• pp.189-203
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• 2013

The purpose of this study is to build a GIS database that can utilized to provide a multi-dimensional analysis of aquatic health ecosystem. Especially, it was to build a GIS database for comprehensive analysis using the aquatic ecosystem health. So we collected data on aquatic ecosystem health assessment, Korea Reach File(KRF), Stream Naturalness and Water Environmental Information System, and detailed analysis of the collected data was performed. In addition, the core objects were extracted from individual data and a related entity was derived by pulling out the items associated with thematic characteristics and classifying them. The establishment of GIS database makes it possible to support the decision making for the user to quickly understand the information of water environment. Therefore, the database will provide the information for the effective management on water environment.

• Journal of The Korean Association For Science Education
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• v.31 no.1
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• pp.14-31
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• 2011

This study investigated pre-service science teachers' motivation for career choice and their self-image as a science teacher. Although their motivations for becoming science teachers were very personal, three major characteristics emerged. First, during the process of their growth, their interest in education and science existed separately, and later the two interest were naturally focused on the job of a science teacher. When they find out that teaching science is right for them, they developed their inner motivation. Second, teaching opportunities to teach science subjects, including classroom observations, TA, tutor, and teacher-aid, played an essential role for them in finding their aptitude for science teaching. Third, their teaching-related experiences were very effective in building up their self-image as a science teacher and in preparing for the job. It also reinforced their inner motivation, which was important in finding their direction in life as a science teacher. Fourth, there were two categories for the self-image as a science teacher. One was teaching-oriented and the other was science subject-oriented. These images for the science teacher were closely connected with their inner motivation for science teaching.