• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.2
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• pp.53-60
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• 2011

This study was conducted to investigate the effect of hydropower factors (watershed, gross head), operation ratio and unit electricity cost on the benefit-cost ratio (B/C ratio) of small hydropower using agricultural reservoirs. The equation of B/C ratio was expressed as a function of watershed area, gross head, operation ratio and unit electricity cost. The benefit increased with watershed area, gross head and unit electricity cost, while the cost increased with watershed area and gross head but decreased with operation ratio. The B/C ratio increased with watershed area, gross head, operation ratio and unit electricity cost. While the effect of gross head on the B/C ratio decreased with watershed area, the effect of operation ratio and unit electricity cost on the B/C ratio increased with watershed area. The operation ratio is an important factor to affect the B/C ratio and therefore we need to develop hydropower for the heightened dams to expect high operation ratio due to continuous water release. The unit electricity cost is also an important factor to affect the B/C ratio and the B/C ratio was always below 1 unless unit electricity cost is over 60 Won/kWh under given conditions. The reservoirs with economic feasibility for small hydropower development were three in 21 when the equation of B/C ratio was appled to the study reservoirs. The results can be used to choose the appropriate reservoir with economic feasibility for development of small hydropower.

• Structural Engineering and Mechanics
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• v.84 no.5
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• pp.675-684
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• 2022

The conventional single-degree-of-freedom (SDOF) system is appropriate for dynamic response analysis of paneltype structures without an opening. However, the typical building structures usually have four-sided fixed walls having an opening. Therefore, it may induce a considerable error when dynamic responses are estimated based on the conventional SDOF system, since the SDOF system cannot consider the effect of an opening during the SDOF analysis. For this reason, this study proposes a new SDOF system to consider the effect of an opening by adjusting its load-mass factor. The load-mass factor can be modified based on the assumption that the behaviors of the four-sided fixed wall with an opening is very similar to the behaviors of the same size wall without an opening, when the uniformly distributed blast loaded area is identical. In order to confirm a feasibility of the proposed SDOF system, a series of numerical simulations were carried out for the four-sided fixed reinforced concrete (RC) wall under a blast load. The dynamic responses estimated from the proposed SDOF system and the conventional SDOF system were compared with the dynamic responses evaluated from the finite element (FE) analysis. Especially, for the maximum dynamic responses except for 50% opening case, the proposed SDOF system had about 1.1% to 25.7% normalized errors while the conventional SDOF system had about 4.1% to 49.1% normalized errors.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.605-607
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• 2011

A Study on the flow-structure characteristics of a 3/2 way pneumatic valve is essential for optimizing the performance of ship engines. It is important for the valve to have desirable safety factor am reduced weight from the safety and economic point of view. In this study, we capture flow-structure characteristics of 3/2 way pneumatic valve. This is optimized based on the proper design criteria. The air at a pressure of 30 bar is the working fluid which is made to fill in the tack in short time. This time is defined as the filling time. The flow and structure analysis is performed for three cases under maximum stress and safety factor. In optimum design, considering the flow-structure characteristics, we model twenty seven cases by using DOE(design of experiments) method Here, analysis for each cases is performed and then metamodels are created We obtain optimized parameters and then analysis is repeated to compare with the initial model. Finally, the feasibility of the optimum design is verified.

• Journal of Information Technology Services
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• v.18 no.5
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• pp.119-132
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• 2019

This study aims to analyze how specific features of a mobile platform such as economic feasibility, interactivity, safety, and design are correlated with perceived ease of use and customer satisfaction, targeting those who purchase delivery food on a mobile platform dedicated to delivery services. A survey was conducted on customers who had bought delivery food on a mobile platform and the data collection was conducted from August 19, 2019 to September 18, 2019, using 300 mobile platform service users. A total of 300 copies were retrieved. 249 valid samples of 300 copies were analyzed with SPSS 23.0 and AMOS 23, and In addition, programs including SPSS and AMOS were used for the analysis of frequency, confirmatory factor, reliability and validity, correlation and structural equation model. Major findings of such analysis are as follows. First, design characteristic of a mobil platform had relevant impacts on perceived ease of use. However, economic feasibility, interactivity, and safety did not significantly affect perceived ease of use. Second, perceived ease of use had a significantly influenced on the extent of customer satisfaction. Hence, from practical and academical point of views based on the results of this analysis, this study is expected to provide directions and some practical and useful implications for a mobile platform for food delivery services.

• International Journal of Highway Engineering
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• v.18 no.2
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• pp.51-60
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• 2016

PURPOSES : The applicability of the mechanics-based similarity concept (suggested by Feng et al.) for determining scaled variables, including length and load, via laboratory-scale tests and discrete element analysis, was evaluated. METHODS: Several studies on the similarity concept were reviewed. The exact scaling approach, a similarity concept described by Feng, was applied in order to determine an analytical solution of a free-falling ball. This solution can be considered one of the simplest conditions for discrete element analysis. RESULTS : The results revealed that 1) the exact scaling approach can be used to determine the scale of variables in laboratory tests and numerical analysis, 2) applying only a scale factor, via the exact scaling approach, is inadequate for the error-free replacement of small particles by large ones during discrete element analysis, 3) the level of continuity of flowable materials such as SCC and cement mortar seems to be an important criterion for evaluating the applicability of the similarity concept, and 4) additional conditions, such as the kinetics of particle, contact model, and geometry, must be taken into consideration to achieve the maximum radius of replacement particles during discrete element analysis. CONCLUSIONS : The concept of similarity is a convenient tool to evaluate the correspondence of scaled laboratory test or numerical analysis to physical condition. However, to achieve excellent correspondence, additional factors, such as the kinetics of particles, contact model, and geometry, must be taken into consideration.

• Korean Journal of Construction Engineering and Management
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• v.8 no.6
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• pp.129-138
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• 2007

According to the preceding research outcomes, feasibility studies on public construction projects were incorrect and subjective. To resolve the problems, Korean government initiated Preliminary Feasibility Study (PFS) system prior to undertaking the main feasibility study. The PSF can be categorized into four areas such as road, railroad, harbor, airport, and Culture & Tourism (C&T). Especially when it comes to complex due to the introduction of five-weekday working system and local $government^{\circ}{\phi}s$ self administrative system. As a result, the standardization and legislation of the PSF can not be operated effectively. Accordingly this paper seeks to 1) identify actual condition of conducted PSF in C&T; 2) set up analytical model considering cost factor of economical efficiency and seek obstacles of PSF system; 3) suggest improvement plan for construction PSF projects.

• Journal of the Korean housing association
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• v.5 no.1
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• pp.71-84
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• 1994

This article tries to develop an instrument for assessing the quality of housing environment by using 67 housing environment variables. The method of factor analysis is used to explore the dimension of the quality of housing. As the result, 5 dimensions of housing environment are extracted. They are, according to the order of their importances, house structure and indoor environment, outdoor facilities and natural environment, indoor facilities and economy, public facilities and social relationship, and convenient facilities and residential feasibility.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.709-712
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• 1998

A new ZVS-CV PWM converter with power factor correction (PFC) function is presented in this paper. The new topology is a integration of a boost converter and a ZVS-CV topology in a single power conversion stage. The new converter can be regulated in pulse-width modulation (PWM) by universal integrated control circuits. Some design considerations are given in detail. A laboratory prototype has been implemented to show the feasibility of the approach and the analysis.

• Korean Journal of Construction Engineering and Management
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• v.18 no.6
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• pp.89-97
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• 2017

The number of Aged Apartment units is expected to increase as time went on. Living standards are getting better and they want a new apartment space as the economy progresses. Therefore, it is necessary to prepare for the increasing remodeling market through the feasibility evaluation method that can be applied to the remodeling project of the apartment house. The purpose of this study is to analyze the social pricing factors affecting the Officially assessed individual House Price for the analysis model of commercial house remodeling. The collected samples were analyzed using multiple regression analysis of 350 prices included in 127 lots. Middle school level, high school level, total number of households, and floor area ratio were extracted. As a result of comparing the Officially assessed individual House Price by applying to the remodeling case, the difference between the existing Officially assessed individual House Price and the improvement Officially assessed individual House Price is different. The accessibility with the subway station is included in the land price, and there is no change in the number of stories and directions because it is customized remodeling. There was a difference in the disclosure price depending on the type of factor extraction by the evaluator in a batch application of the disclosure price factors. The research can be used as a model for future remodeling business feasibility analysis.

• Journal of Engineering Education Research
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• v.15 no.5
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• pp.64-68
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• 2012

Design factors such as design objects establishment, analysis, synthesis, production, test and evaluation should be educated in a systematic way. Also design ability to reflect practical restrictive conditions such as industrial standards, economic feasibility, environmental impact, aesthetics, safety and reliability, ethical impacts and social impacts should be cultivated. In this paper, we explain the meaning of these terms and propose a systematic engineering design education framework satisfying Korean engineering education accreditation criteria. We also present a simple implementation in information network engineering.