• Journal of Korean Society of Environmental Engineers
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• v.35 no.1
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• pp.38-44
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• 2013

To construct the system controlling the aeration volume for D wastewater treatment plant effectively, the fluctuation of aeration volume was analyzed with changes of factors of the influent. As a result, the range of aeration volume was wide to maintain the certain concentration of DO, and the key factor to decide the aeration volume was found to be the temperature, F/M ratio, the loading rate of $BOD_5$ and T-N of the influent. Among the factors, the temperature of the influent had the most decisive effect on the aeration volume. The result showed that $45.8m^3/h$ of the aeration volume was needed with an increase of $1^{\circ}C$ of the influent, and the effect of the season was considered. Since the temperature of the influent is affected by a change of season, same as F/M ratio, the loading rate of the influent and the concentration of MLSS, it seemed that the change of the temperature of the influent affects the aeration volume even more. Therefore, it is preferable to consider the loading rate of the influent and F/M ratio altogether, rather than considering only one factor when deciding aeration volume.

• Journal of Korean Society of Transportation
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• v.30 no.3
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• pp.95-106
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• 2012

The railway service in the Seoul metropolitan area is facing variety of l changes such as extension of service coverage, new construction, and introduction of express service which in turn causes changes on demands. The demand affects train operation characteristics (frequency of service, train formation) as well as on the congestion rate which is one of the major evaluation index in metropolitan area user service. For the efficient operation of the train, the relationship among the minimization of fleet number, operating cost, and service level has been analyzed. Using the Powersim, which is a system dynamics (System Dynamics) simulation program for realizing optimized simulation for train-formation, this paper identified that some stations of Gyeong-bu line exceeded limit congestion rate(150%) of a fleet already that means it is best to maintain current condition of the line; however, the Gyeong-in line and the Gwa-chon line showed no excess of the limit congestion rate so that it is possible to reduce 2-4 fleets of train for efficient operation. In addition, in case of Jang-hang line between Cheon-an and Sin-chang, a train consisting of 10 fleets provides services which is same formation of train for Gyeong-bu line. This study proved that the congestion rate will not rise greatly with only 4 fleets of a train for the service in Jang-hang line, and it is considered that a study for shuttle service between Cheon-an and Sin-chang is necessary.

• Journal of Practical Engineering Education
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• v.12 no.1
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• pp.163-176
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• 2020

Promoting job growth and quality has been central to developing countries to reduce poverty for decades. In this regard, Nepal is not unique in its need to develop effective TVET programme as it is considered showing positive association with workforce development and productivity. While the copious academic literature has highlighted upon staff training programme in general education, it encounters lack of adequate attention in the field of TVET education. The purpose of the study is to identity and prioritise the professional development needs for the teachers of TVET sector in Nepal. A sample(N=317) of Nepalese teachers from seven provinces were asked to answer the scale. The Borich needs assessment model was employed to assess the perceived level of importance and present preferred training modules among 29 teaching subjects. Moreover, a quadrant analysis using 2×2 matrix was used as a diagnostic tool to denote overriding training topics. The result shows that following competence skills constructs were perceived to be in high need of enhancement as well as in existence of discrepancies: 'occupational characteristics of TVET trainer', 'training needs analysis and curriculum development', 'curriculum development based on national competence standard(NCS)', and 'Institution management evaluation'.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.588-596
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• 2019

The purpose of this study is to propose an ICT-oriented teacher curriculum in order to improve early childhood teacher's competency using ICT instructional media. To this end, a survey was conducted to investigate the importance and current level of early childhood teacher's competency. After identifying the necessity of ICT instructional media competency, the contents of an ICT-oriented teacher curriculum were designed. A survey of teacher competency among 207 teachers showed the highest educational need for ICT instructional media competency. In addition, ICT-based teacher curriculum was classified into ICT literacy education and ICT utilization education based on the analysis results of sub-indexes on ICT instructional media competency. Each part was hierarchized into three levels of awareness, application, and spread according to the teacher's competency level and the educational contents were suggested based on the goals set for each level. In this study, it consisted of ICT literacy education, including understanding educational policy related to ICT utilization, understanding the goals and assessment of the ICT curriculum and ICT utilization education, including the use of teaching and learning methods, application of digital technology, ICT learning environment building and management for developing teacher professionalism related to ICT instructional media.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.2
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• pp.327-334
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• 2016

In this paper, we propose a hardware architecture of transform and quantization for high-perfornamce HEVC(High Efficiency VIdeo Coding) encoder. HEVC transform decides the transform mode by comparing RDCost to search for the best mode of them. But, RDCost is computed using the bit-rate and distortion which is computed by transform, quantization, de-quantization, and inverse transform. Due to the many calculations and encoding time, it is hard to process high resolution and high definition image in real-time. This paper proposes the method of transform mode decision by comparing sum of coefficient after transform only. We use BD-PSNR and BD-Bitrate which is performance indicator. Based on the experimental result, We confirmed that the decision of transform mode can process images with no significant change in the image quality. We reduced hardware area by assigning different values at the same output according to the transform mode and overlapping coefficient multiplied as much as possible. Also, we raise performance by implementing sequential pipeline operation. In view of the larger process that we used compared with the process of reference paper, Our design has reduced by half the hardware area and has increased performance 2.3 times.

• Journal of Environmental Policy
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• v.9 no.1
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• pp.83-107
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• 2010

Urbanized environments are constructed to estimate peak flow and cost savings in response to possible BMP allocation at a watershed scale. The main goal is to explore the proper allocation of sub-watershed level BMPs for peak flow attenuation at a watershed scale. Since several individual site scale BMPs work as a form of aggregated BMPs at a sub-watershed scale, it is a question as to how to properly allocate the sub-watershed level BMPs at a watershed scale. The Hydrological Simulation Program-FORTRAN (HSPF) is set up for a hypothetically urbanized watershed. A peak flow is determined to be the primary variable of interest and targeted to characterize the spatial distribution of aggregated BMPs. Construction cost of a regional pond forms the basis of the economic valuation. The results indicate that when total size of BMPs is constant in the entire watershed, (1) it is most effective to have aggregated BMPs in some upper sub-watersheds while the BMPs in either the mainstem sub-watershed or a single sub-watershed are the least effective choices for peak flow attenuation at a watershed scale; (2) savings exist between allocation differences and reduced peak flow increases cost savings. The largest saving is found in the strategy of aggregated BMPs in some upper sub-watersheds. These findings, however, call for follow-up site specific case studies revisiting the watershed scale impacts of BMP allocation. Then, it will be argued that location and extent of decentralization are considerable policy variables for an alternative stormwater management policy at a watershed scale.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.404-411
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• 2019

In this study, the HEC-HMS was applied to determine rainfall-runoff processes for the Gokgyuchun basin. Several sub-basins have large-scale reservoirs for agricultural needs and they store large amounts of initial runoff. Three infiltration methods were implemented to reflect the effect of initial loss by reservoirs: 'SCS-CN'(Scheme I), 'SCS-CN' with simple surface method(Scheme II), and 'Initial and Constant rate'(Scheme III). Modeling processes include incorporating three different methods for loss due to infiltration, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated using an optimization technique with trial and error method. Performance measures, such as NSE, RAR, and PBIAS, were adopted to aid in the calibration processes. The model performance for those methods was evaluated at Gangcheong station, which is the outlet of study site. Good accuracy in predicting runoff volume and peak flow, and peak time was obtained using the Scheme II and III, considering the initial loss, whereas Scheme I showed low reliability for storms. Scheme III did not show good matches between observed and simulated values for storms with multi peaks. Conclusively, Scheme II provided better results for both single and multi-peak storms. The results of this study can provide a useful tool for decision makers to determine master plans for regional flood control management.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.331-343
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• 2019

The purpose of this study is to observe the trends of heart age of Koreans by using the predictor of heart age of the Framingham Heart Study. The subjects were 20,012 adults aged 30~74 years who were enrolled in the Korean National Health and Nutrition Examination Survey from 2005~2013. They filled in the determinants data and they had no history of cardiovascular disease (CVD). The heart age was calculated using a non-laboratory based model of prediction. The difference of heart age and chronological age, and the rate of excessive heart age over 10 years were calculated. The annual trend, the difference according to gender, the age bracket and geographic region, the heart age were all evaluated. Data analysis performed using the SAS program (version 9.3). Complex designed analysis was done. The heart age showed differences according to gender, age bracket and geographic region. The heart age is a useful comprehensive indicator for predicting the CVD events in the near future. So, it could be used for the purposes of exercising caution and guidance on CVD for administering medical care. It is strongly recommended to use heart age as an indicator for customized medical management to focus efforts on relatively vulnerable subjects and their factors for CVD. Further study on Koreans' customized heart age is needed.

• Korean Journal of Construction Engineering and Management
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• v.20 no.3
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• pp.39-45
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• 2019

Crew productivity in the construction industry is an important indicator of soundness and efficiency of work process, since all works in a site are conducted as groups of people. A survey was conducted in order to reveal importance and performance of major management factors affecting crew productivity in road bridge construction site using IPA. As a result of the analysis, it was found that 'Construction equipment' and 'Human resource related' factors among five major-categories are most important but with low performance. Furthermore, from another analysis with 27 factors of sub-categories, it is revealed that factors needed sustained attention are four, namely 'Just-in-time machinery delivery', 'Formation of a crew members', 'Skill of workers', and 'Site control and management', whereas those needed much more improvement are five, such as 'Machinery performance', 'Clearity of Design', 'Clearity of shop drawing', 'Timing of work instruction and approval', and 'Clearity of work instruction'. Findings from this study will enable road agencies as well as road construction experts to enhance crew productivity in a site.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.261-267
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• 2020

The demand for faster, lighter, and thinner portable electronic devices has brought about a change in semiconductor packaging technology. In response, a stacked chip-scale package(SCSP) is used widely in the assembly industry. One of the key materials for SCSP is a die-attach film (DAF). Excellent flowability is needed for DAF for successful die attachment without voids. For DAF with high flowability, two-step curing is often required to reduce a cure crack, but one-step curing is needed to reduce the processing time. In this study, DAF composition was categorized into three groups: cure (epoxy resins), soft (rubbers), hard (phenoxy resin, silica) component. The effect of the composition on a cure crack was examined when one-step curing was applied. The die-attach void and flowability were also assessed. The cure crack decreased as the amount of hard components decreased. Die-attach voids also decreased as the amount of hard components decreased. Moreover, the decrease in cure component became important when the amount of hard component was small. The flowability was evaluated using high-temperature storage modulus and bleed-out. A decrease in the amount of hard components was critical for the low storage modulus at 100℃. An increase in cure component and a decrease in hard component were important for the high bleed-out at 120℃(BL-120).