• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.26 no.3D
• /
• pp.425-433
• /
• 2006

The presented work provided a predictive equation for dynamic modulus of hot mix asphalt, which showed higher reliability and more simplicity. Lots of test result by UTM at laboratory has been used to develop the precise predictive equation. Evaluation of dynamic modulus for 13mm and 19mm surface course and 25mm of base course of hot mix asphalt with granite aggregate and two asphalt binders (AP-3 and AP-5) were carried out. Superpave Level 1 Mix Design with gyrator compactor was adopted to determine the optimum asphalt binder content (OAC) and the measured ranges of OAC were between 5.1% and 5.4% for surface HMA, and around 4.2% for base HMA. The dynamic modulus and phase angle were determined by testing on UTM, with 5 different testing temperature (-10, 5, 20, 40, & $55^{\circ}C$) and 5 different loading frequencies (0.05, 0.1, 1, 10, 25 Hz). Using the measured dynamic modulus and phase angle, the input parameters of Sigmoidal function equation to represent the master curve were determined and these will be adopted in FEM analysis for asphalt pavements. The effect of each parameter for equation has been compared. Due to the limitation of laboratory tests, the reliability of predictive equation for dynamic modulus is around 80%.

• Journal of IKEEE
• /
• v.18 no.3
• /
• pp.383-391
• /
• 2014

In this paper, temperature, pressure and flow analysis system for testing a fuel filter of a diesel engine at the low-temperature environment in winter, is proposed. The light oil of diesel engine below a specific temperature is changed to the waxing materials like paraffin, and it prevents engine to start easily because of reducing fluidity. Thus, built-in block heater should be installed with fuel filter in order to solve this problem. And it is necessary to design evaluation system that can analyze the performance according to temperature, pressure and flow characteristics near fuel filter at a very low temperature. In this paper, we measured a physical quantity related to the performance of around the fuel filter using the proposed system, and analyzed their characteristics. Also the measured data is transferred to remote user by using a web server of embedded systems, and analyzed their conditions in remote place via web browser in order to know the operating status of fuel filter. We installed the proposed system in a small test chamber to verify the performance and took an experiment in normal temperature and very low temperature, and could obtain temperature, pressure and flow of near the fuel filter. As a result, the fuel flow could be improved during operation of the fuel heater.

• The Journal of the Korea Contents Association
• /
• v.20 no.4
• /
• pp.591-600
• /
• 2020

The decrease in the number of school-age population, the introduction of university evaluation and educational capacity enhancement projects have made the enrollment rate and employment rate important indicators. Accordingly, universities are making great efforts to improve the competitiveness of their universities by increasing students' major satisfaction. The purpose of this study is to find out whether art and music students major selection motivsion of affects major satisfaction for career preparation behavior. For this survey, students of arts and physical education at K University in Gyeonggi-do were surveyed and 197 questionnaires were used as analysis data. As a result of the study, it was found that major selection motivation had a significant static effect on career preparation behavior and major satisfaction, and major satisfaction was analyzed to have a complete mediating effect on the effect of major selection motivation on career preparation behavior. With on the results of this study, in the future, universities will need an efficient curriculum to enhance students' majors satisfaction. To that end, we should develop the theoretical and practical curriculum so that students can actively participate, operate programs such as operation of comparative subjects and on-demand education, and raise the level of education. To this end, the interest and active support of the industry-academia-research are required.

• Journal of Mushroom
• /
• v.12 no.4
• /
• pp.244-250
• /
• 2014

Phylogenic relationships and morphological characteristics were classified and investigated among the 233 collected strains of Agaricus spp. The 38 strains were differently identified as different characteristic group using analysis of ITS regions in rDNA. A. bitorquis was showed close relationship in groupA whereas A. campestris was in groupC as different characteristic group among with A. bisporus. There was no phylogentic difference with strains collected by country and different pileus colored Agaricus bisporus. Also the strains were cultivated twice to investigate morphological characteristics of fruiting bodies. The characteristics and yield of collected strains were compared with molecular varieties and seasons by the cultivation. In this result, A. campestirs showed good yield and quality in terms of hardness off-white mushroom was more harder than other number of A. bisporus. Also earliness and color of pileus was influenced by external environment all conditions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.4
• /
• pp.857-864
• /
• 2009

This study aimed at developing the two stage and dual filtration system. It has a sand + activated carbon layer above the underdrain system and a sand layer above the middledrain system for pretreatment. When retrofitting an old filter bed or designing a new one, this technology can substitute the existing sand filter bed without requiring a new site. In order to extend the filtering duration, the upper layer of the filter bed consists of the rapid sand filtration with large particles which pre-treats and removes coarse particles and turbidity matters. The middle layer has biological activated carbon(BAC) and granular activated carbon(GAC) to eliminate dissolved organic matters, disinfection by-products precursors etc. The lower layer consists of the sand filtration for the post filtering mode. In this study, a pilot plant of two stage and dual filtration system was operated for 4 months in the S water treatment plant in Kyounggi-Do. The stability of turbidity was maintained below 1NTU. The TOC, THMFP and HAAFP were removed about 90% by two stage and dual filtration system, which is almost 2 times higher than S WTP. From analysis result of HPC along the depth of activated carbon + sand layer at 2nd stage, microorganism was mostly not detected, however, increment of HPC was shown as it becomes deeper. It indicates that growth of microorganism is occurred at activated carbon layer.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.3
• /
• pp.551-561
• /
• 2017

This study attempts to determine the strategy to improve the quality of staff supervision by exploring the experiences of the staff supervision in community welfare centers. For this purpose, multiple case study was performed by conducting in-depth interviews with 10 supervisors for the analysis data and analyzing the resulting themes. The key subjects from their experience were 'Supervisors recognize and prepare the supervision as Challenge and Aspiration', 'Supervision leaves only chaos and frustration', and 'Inspiration from the supervisor and infinite effort result in fruit'. Based on these results, this study suggests the following practical suggestions for the educational, administrative and supportive functions of Supervision. First, educational functions should be proposed as an extension of supervisor's education opportunities and manuals related to educational growth of supervision. Second, the administrative function should be changed to evaluate social welfare institution's evaluation framework so as to evaluate the supervision internal regulation and supervision according to it and various supervision models should be developed. Third, supportive supervision function that can be encouraged for supervisees should be enhanced. This study was meaningful because it presents specific suggestions for supervisors and supervisee's relation and situation in the community welfare center through the qualitative research method.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.37 no.1
• /
• pp.28-42
• /
• 2009

In the wake of categorizing the design changes occurred during the period from 2004 till the first half of 2006 in Choongcheong province area, based on purpose and reason of design changes identified by the Korea National Housing Corp, it included 11 types such as the image of the apartment complex, scenic elements, consideration by the user, prevention of the defect, constructability, site conditions, incompatibility between the activities, superordinate standard, prevention of civic complaints, design details and others, along with 47 subordinate elements. And the evaluation intended to identify the corelation between the number and time of design change approval, frequency and scale of design change by type and the cost variations indicated that; firstly, enhancing the image of the apartment complex proved to be the main reason for design changes, accounting for 22% in terms of frequency and 54.9% in terms of cost variation. Secondly, the higher the increase in cost by design change aimed at improving the image of the complex, the lower the decrease in cost by design change for uncertain reasons, dubbed the inverse proportional relations, indicating that the design changes for uncertain reasons were mostly aimed at reducing the construction cost. Thirdly, with regard to the number of design change approval and the time of the initial approval, twice or less and 90 days or less before completion of the construction work, respectively, accounted for $52{\sim}53%$, indicating the design change deliberation and approval tended to have been carried out collectively in the form of ex post facto approval, which seemed to be attributable to the attempt of reducing the construction cost or budget problem, as a result of comparing with the cases in which the cost was reduced.

• Journal of Korean Society of Environmental Engineers
• /
• v.29 no.6
• /
• pp.706-714
• /
• 2007

This study suggested a method for prediction of residual chlorine and THMs in water distribution system by measurement of residual chlorine, THMs, and other parameters, estimation of chlorine decay coefficients and THM formation coefficients, and simulation of water qualities using pipe network analysis. Bulk decay coefficients of parallel first-order were obtained by bottle tests, and pipe wall decay coefficients of first-order were estimated through evaluation of 5 models, which showed the lowest values of 0.03 for MAE(mean absolute error) and 0.037 MAE in comparison with the observed in field. And bottle tests were conducted to model first-order reaction of THM formation by nonlinear least square regression and the resultant coefficients were compared with the observed in field. As a result, the coefficients of determination$(R^2)$ for the observed and the predicted values were 0.98 in September and 0.82 in November, and the formation of THMs was predicted by modeling.

• Journal of Science Education
• /
• v.41 no.1
• /
• pp.60-79
• /
• 2017

The purpose of this study was to develop a program for the history of science and technology in order for the technical high school students to understand the nature of science (NOS). The program was composed of the six topics based on the textbooks such as convergence science and physics I, and was taught to 290 10th graders at a technical high school located in the metropolitan area. The questionnaire about NOS was asked the students before and after the instruction, so as to investigate the effect of the program on improving their understandings of NOS. The analysis followed t-test and ANOVA using SPSS 23.0 for Windows program. The questionnaire based on the conceptual framework of the four themes of the NOS (Lee, 2014). The research findings were as follows. First, the program was effective in improving their understanding of NOS since the t-test result was significant statistically for the overall domains of NOS (p<.01). Second, there was no significant gender differences in the understanding of NOS among technical high school students (p<.05), neither did their majors (p<.05). Third, all domains in NOS were statistically correlated (p<.01), and in a particular, each domain was consistently correlated with the aspect of the nature of the interactions among science, technology, and society. Hence, the further studies should be conducted to examine how the history of science and technology effects the understanding of the NOS and how the domains in NOS affected each other.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.6 no.3
• /
• pp.95-106
• /
• 2003

This study evaluated the architectural density of urban district using airborne laser scanning(ALS) that is a method used in urban planning, water resources and disaster prevention with high interest recently. First, digital elevation model(DEM) and digital surface model(DSM) was constructed from Light detection and ranging(LiDAR). For getting the height of building, ZONALMEAN filter was used in DEM and ZONALMAJORITY filter was used in DSM. This study compared the floor from filtering with the floor from survey and got standard error, which is ${\pm}0.199$ floor. Also, through the overlay and statistical analysis of total-area layer and zone layer, we could present floor area ratio by zone. As a result of comparison with floor area ratio between airborne laser scanning data and survey data, the standard error of floor area ratio shows ${\pm}2.68%$. Therefore, we expect that airborne laser scanning data can be a very efficient source to decision makers who set up landuse plan in near future.