• Korean Journal of Soil Science and Fertilizer
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• v.40 no.2
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• pp.109-113
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• 2007

In order to establish the fertilization and soil management method in Gyehwa reclaimed tidal land, we investigated soil property and actual farming condition. Soil properties of 100 field paddy soil and farming surveys of 177 farm households were conducted. Average of effective soil depth was 17.8 cm, which was very smaller than the optimum level 50 cm. The hardness and bulk density of subsoil were $12.40kg\;cm^{-2}$ and $1.59g\;cm^{-3}$, respectively. These results showed that soil physical condition of Gyehwa reclaimed tidal land was very poor. Soil salinity ranged from 0.03 to 0.12%, and average of pH was 6.0, which implied that desalinization of Gyehwa reclaimed tidal land was progressed. However, soil nutrients in Gyehwa reclaimed tidal land were very unbalanced conditions as following, available phosphate $58mg\;kg^{-1}$, available silicate $85mg\;kg^{-1}$, cation exchangeable capacity $7.4cmolc\;kg^{-1}$ and organic matter $8.6g\;kg^{-1}$. On the farm household in Gyehwa reclaimed tidal land, fertilization amounts were $200-54-61(N-P_2O_5-K_2O)kg\;ha^{-1}$ They mainly practiced spring tillage(84%) rather than autumn tillage(16%), and only 14% of them applied rice straw annually in the paddy soil.

• Journal of Industrial Convergence
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• v.20 no.5
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• pp.39-59
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• 2022

We analyze the perceptions and requirements of early childhood teachers for artificial intelligence(AI) education to develop an AI education program for 5-year-olds. As for the research methodology, we conducted a survey and an in-depth interview to extract the AI educational elements centering on the analysis stage, the first stage of the ADDIE model. The research result is that first, it is necessary to design a curriculum that combines the contents of early childhood education and AI education to be naturally accepted as AI education for 5-year-olds. Second, an evaluation tool for AI education that can showcase the teacher's reflection should be developed systematically. Third, it is necessary to support a play-centered AI education support and environment for early childhood teachers. Lastly, it is essential to establish a system that can be continuously operated in the field of early childhood education in consideration of AI education in the non-curricular curriculum. It is expected that in the future, a play-oriented AI education program for 5-year-olds will be developed to spread awareness of AI education for infants and present an AI education approach for each age and stage of learners.

• Korean Journal of Construction Engineering and Management
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• v.24 no.4
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• pp.3-13
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• 2023

The purpose of this study is to compare and analyze the performance and work productivity of wet type pavement cutters and sludge suction type pavement cutters (hereinafter referred to as automatic pavement cutters) developed to reduce scattering dust. We first investigated the development status of wet type manual pavement cutters that are mainly used in Korea and automatic pavement cutters, and analyzed the pavement cutting work in detail. And the standard cutting performance was derived by measuring the cutting time by depth by applying the two equipment to the test bed under the same conditions. However, there is a limitation that the data measured in the test bed does not reflect the various variables of the actual pavement cutting site. Therefore, in this study, data was collected through field surveys, and the correlation between cutting distance and time was analyzed, and then a model for calculating the productivity of pavement cutters was presented through simple regression analysis. As a result of comparative analysis of the values derived from the regression equation with the standard cutting performance derived from the test bed, the cutting performance derived through the regression equation showed a similar trend to the standard cutting performance. Finally, we verified the usability of the automated pavement cutter developed by qualitatively analyzing three tasks that are difficult to measure quantitatively but affect productivity.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4B
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• pp.335-344
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• 2006

In this study, sequential mixing model (SMM) was proposed based on the Taylor's theory which can be summarized as the fact that longitudinal advection and transverse diffusion occur independently and then the balance between the longitudinal shear and transverse mixing maintains. The numerical simulation of the model were performed for cases of different mixing time and transverse velocity distribution, and the results were compared with the solutions of 1-D longitudinal dispersion model (1-D LDM) and 2-D advection-dispersion model (2-D ADM). As a result it was confirmed that SMM embodies the Taylor's theory well. By the comparison between SMM and 2-D ADM, the relationship between the mixing time and the transverse diffusion coefficient was evaluated, and thus SMM can integrate 2-D ADM model as well as 1-D LDM model and be an explanatory model which can represents the shear flow dispersion in a visible way. In this study, the predicting equation of the longitudinal dispersion coefficient was developed by fitting the simulation results of SMM to the solution of 1-D LDM. The verification of the proposed equation was performed by the application to the 38 sets of field data. The proposed equation can predict the longitudinal dispersion coefficient within reliable accuracy, especially for the river with small width-to-depth ratio.

• Journal of Korea Port Economic Association
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• v.33 no.3
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• pp.35-52
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• 2017

Interest and demand in heavy cargo logistics is increasing and becoming more diverse as economic scales have expanded and manufacturing activity has increased. Although cargo moves via maritime and/or land transportation, there is currently insufficient research on the actual condition of heavy cargo logistics. The purpose of this study is to carry out an in-depth analysis of heavy cargo laws, systems, logistics patterns, and current transportation status. By proposing measures to solve existing problems, this study aims to make an important and ongoing contribution to the scarcely studied field of heavy cargo logistics. The result of regression analysis on the main seven factors show that transportation frequency and law/system structure have a positive effect on working conditions. Furthermore, the result of correlation analysis on the main seven factors show that the cargo weight variable is highly positively correlated with cargo size. Also, the working conditions variable is highly positively correlated with the law/system structure. Detailed proposal measures to solve existing problems are summarized as follows. First, it is necessary to establish a clear concept of heavy cargo as numerous existing definitions differ. Second, laws and provisions relating to maritime and land transportation of heavy cargo need to be established and consolidated as current applicable legislation is insufficient. Third, the classification system for heavy cargo transportation needs improvement. Fourth, it is necessary to improve transportation performance statistics and the aggregate criteria system. Finally, the management system of heavy cargo also needs improvement.

• Korean journal of communication and information
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• v.62
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• pp.51-73
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• 2013

This study is an attempt to find out the meaning of game to middle-aged women who enjoy internet web board game as part of the leisure. In order to discover the perceptions and emotions of middle-aged women regarding game, in-depth interviews with the five women of 48 to 63-year-old were conducted. The results are: First, the web board games to middle-aged women is an opposition of labor, but at the same time a part of day-long procedure of labor. Second, most middle-aged women are not in an autonomous environment where they can pursue active hobbies. Third, middle-aged women do not tolerate sacrificing money or housework on game because the web board games are regarded as a worthless activity. Finally, middle-aged women do not transform the existing social relationships into online relationships, nor form new social relationships through internet. Based on these results, we could draw a rough picture overviewing the gaming experience of middle-aged women, which has been more or less ignored in academic field. game experiences; middle-aged women; web board game; leisure/labor; game culture;

• The Korean Journal of Ecology
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• v.27 no.5
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• pp.269-281
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• 2004

The survey of birds in Nakdong River Basin was conducted from March in 2003 to February in 2004. This study shows that the population of birds was 94,481 individuals and 114 species. The bird recorded in Daemadeung (Ⅰ) was 21,781 individuals and 55 species. It is surrounded with silt to have a better condition for a habitat and the rest place than other areas in the Nakdong River Basin. In the traits of the groups, Grebes were well established in the lower estuary(Eulsook islet), Cormorants in the main stream of the Nakdong River and around West Nakdong River (F). Swans, Shelduck and Shorebirds were using silt in the lower estuary where the depth of water is shallow, dabbling ducks were also established in West Nakdong River (F) and Yummak (C), diving ducks in the upper Nosan Watergate in West Nakdong River (F). Besides, land birds was distributed in the Yummak (C), Eulsook islet (A) and West-Nakdong River (F). Because they are connected with the artifical forest in Eulsook Islet Garbage Field and Ⅱwoong islet, it is good for the land birds and the water birds to have a habitat in this kinds of vacant lot. The Nakdong River Basin is not only an important area as the habitat and rest place for ducks and geese but also one of the areas where we can not get out of the temptation to development. To preserve effectively the natural habitat from human s intervention, it needs to keep supervising in Daejeo Watergate (E) and the upper area Noksan watergate in West Nakdong River (F) and Yummak (C).

• Progress in Medical Physics
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• v.11 no.2
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• pp.117-122
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• 2000

The IP(imaging plate) has been widely used to measure the two-dimensional distribution of incident radiation since it has a high sensitivity, reusability, a wide dynamic range, a high position resolution. Particularly, the easiness of acquiring digitized image using IP poses a strong merit because recent trend of data handling prefers image digitization. In order to test its usefulness in photon beam dosimetry, we measured the off-axis ratio(OAR) on portal planes and percent depth dose(PDD) within a phantom using IP, and compared the results with the data based on EGS4 Monte Carlo particle transport code, ion-chambers, conventional films. For the measurement, we used 6 MV X-rays, various field sizes. As a result, IP showed significant deviation from ion-chamber measurement: a significant overresponse, 100% greater than that of ion-chamber measurement at deep part of the phantom. Filtration of low-energy scattered photons at deep part of the phantom using 0.5 mm thick lead sheets did improve the result, only to the unacceptable extent. However, portal dose measurement showed possibilities of If as a dosimeter by showing errors less than 5%, as compared with film measurement.

• Journal of Gifted/Talented Education
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• v.26 no.2
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• pp.299-318
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• 2016

The purpose of study was to explore science teachers' practical knowledge on teaching the gifted in science; namely, what kinds of instructional methods did they perceive as effective approaches based on their teaching experience with the gifted? Twelve science teachers who had 4-11 years of teaching experiences with the gifted students at the gifted center under the local educational offices participated in the study. The data source included in-depth individual interviews with the teachers. In results, the teachers became more aware of the academic potentials and characteristics of the students and had made efforts to develop their instructional methods more fitting to the characteristics and needs of the gifted. They emphasized four instructional aspects: 1) experience of authentic inquiry process and methods, 2) group activities focusing on leadership, communication and collaboration, and empathetic attitudes, 3) tasks promoting creative and convergent thinking, and 4) career awareness in the field of science, technology, and engineering. It is expected that this study provides more practical implications and insights for novice science teachers in the gifted education.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.493-500
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• 2017

Co-operative education and internships are generally treated as an alternative way to increase the employment rate by resolving the mismatch between college education and the industrial needs of the job specification. Based on a questionnaire survey on Korean universities, this study examined the current status of programs and the operating mechanism for co-operative education and internship to provide policy suggestions for promoting the depth and width of co-operative education in Korean universities. The results of the survey shows that the majority of students carry out internships on a short-term basis and the universities usually lack the capabilities for effectively running the programs of co-operative education and internships. In particular, as a part of the academic curriculum, co-operative education should be focused on the balance and effective linkage between the occupations given to students and the majors in university.