• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.23-27
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• 2007

Many trials have been used to model room impulse responses, all attempting to provide efficient representations of room acoustics. The traditional model designs for room impulse response seem to fail in accuracy, controllability, or computational efficiency. In time domain, a room impulse response is generally considered as the combination of three parts having different acoustic characteristics, initial time delay, early reflection, and late reverberation. This paper introduces new learning hybrid model for the room impulse response. In this proposed model, those three parts are modeled using different models with learning algorithms that determine the length or boundary of each model in the hybrid model. By the simulation with measured room impulse responses, it was examined that the performance of proposed model shows the best efficiency in views of both the parameter numbers and modeling error.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.4
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• pp.491-500
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• 2016

This paper presents a highly efficient aeroelastic optimization method based on a surrogate model; the model is verified by considering the case of a high-aspect-ratio composite wing. Optimization frameworks using the Kriging model and genetic algorithm (GA), the Kriging model and improved particle swarm optimization (IPSO), and the back propagation neural network model (BP) and IPSO are presented. The feasibility of the method is verified, as the model can improve the optimization efficiency while also satisfying the engineering requirements. Moreover, the effects of the number of design variables and number of constraints on the optimization efficiency and objective function are analysed in detail. The accuracy of two surrogate models in aeroelastic optimization is also compared. The Kriging model is constructed more conveniently, and its predictive accuracy of the aeroelastic responses also satisfies the engineering requirements. According to the case of a high-aspect-ratio composite wing, the GA is better at global optimization.

• Architectural research
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• v.8 no.1
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• pp.37-45
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• 2006

A fungal spore transportation model that accounts for the concentration of airborne indoor spores and the amount of spores deposited on interior surfaces has been developed by extending the current aerosol model. This model is intended to be used for a building with a mechanical ventilation system, and considers HVAC filter efficiency and ventilation rate. The model also includes a surface-cleaning efficiency and frequency that removes a portion of spores deposited on surfaces. The developed model predicts indoor fungal spore concentration and provides an indoor/outdoor ratio that may increase or decrease mold growth risks in real, in-use building cases. To get a more useful outcome from the model simulation, an uncertainty analysis has been conducted in a real building case. By including uncertainties associated with the parameters in the spore transportation model, the simulation results provide probable ranges of indoor concentration and indoor/outdoor ratio. This paper describes the uncertainty quantification of each parameter that is specific to fungal spores, and uncertainty propagation using an appropriate statistical technique. The outcome of the uncertainty analysis showed an agreement with the results from the field measurement with air sampling in a real building.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6799-6806
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• 2015

Electric energy consumption is always followed by the introduction of diversity scale-up and state-of-the-art equipments in logistic centers. In order to analyze the status and the characteristic of the electric energy consumption quantitatively, and also to evaluate the efficiency of the electric energy, this research aims to develop an estimation model of standard electric energy consumption for logistic centers. The proposed model applies the thermodynamics theory so as to effectively reflect the peculiarity that the temperature in the logistic center influences the electric energy consumption. And the model consists of the energy consumed by the refrigerator, which can be subdivided into the heat conducted through the wall, the heat convected by the open doors and the heat lost into the goods, and the electric consumption of the machinery equipments. The model also includes a variety of explanatory variables to support an operator of logistics centers in evaluating the efficiency of energy consumption and establishing improvement strategies for energy efficiency. Application of the model developed in this study is discussed with observed data on energy consumption of a logistics center.

• The Journal of the Korea Contents Association
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• v.12 no.7
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• pp.284-294
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• 2012

In the study, we estimate efficiencies using CCR model of DEA, Super efficiency(AP) model, and super-SBM model with the data of 32 regional public hospitals in Korea from 205 to 2009. With Wilcoxon-Mann-Whitney statistics, we analyze efficiency differences for environmental factors(regions, type of hospital, type of operations, type of education training, relative importance of madicaids) among regional public hospitals. The results can be summarized as follows. Firstly, technical inefficiencies of regional public hospitals range from 15% to 17% in CCR model, 13% to 15% in AP model, 7% to 12.6% in SuperSBM model. Second, we confirm that environmental factors of hospitals cause different inefficiencies among them. The implication of this study is that policy and institutional change may need to improve the efficiencies along with internal managerial reform.

• Journal of Energy Engineering
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• v.17 no.1
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• pp.31-37
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• 2008

At present, the target amount of demand-side management and investment cost of EE (Energy Efficiency) program, which consists of high-efficiency appliances, has been estimated simply by the diffusion function based on the real historical data in the past or last year. In the internal and external condition, the penetration amount of each appliance has been estimated by Bass diffusion model which is expressed by time and three coefficients. And enough acquisition of real historical data is necessary for reasonable estimation of coefficients. In energy efficiency, to estimate the target amount of demand-side management, the penetration amount of each appliance should be primarily forecasted by Bass diffusion model in Korea. On going programs, however, lightings, inverters, vending machine and motors have a insufficient real historical data which is a essential condition to forecast the penetration amount using a Bass diffusion model due to the short period of program progress. In other words, the forecast of penetration amount may not be exact, so that it is necessary for the method of forecast to apply improvement of method. In this paper, the penetration amount of high-efficiency appliances is forecasted by Bass, virtual Bass, Logistic and Lawrence & Lawton diffusion models to analyze the diffusion progress. And also, by statistic standards, each penetration is compared with historical data for model suitability by characteristic of each appliance. Based on the these result, in the forecast of penetration amount by diffusion model, the reason for error occurrence caused by simple application of diffusion model and preferences of each diffusion model far a characteristic of data are analyzed.

• Journal of the Korean Home Economics Association
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• v.50 no.6
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• pp.99-117
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• 2012

This study aimed to measure consumer information competency, which indicates consumers' general ability to search and utilize information. The model of this study was constructed in order to identify how consumer information competency influences the efficiency and the effectiveness of external information search. The model was verified with related prior knowledge as a moderator variable in order to understand holistic consumer information search activity. The result of the study is as follows. First, the concept of consumer information competency was constructed with four sub-abilities: define, search, extract, and synthesis & use. The ability of define was the highest, as opposed to the ability of extract, which was the lowest. Second, consumer information competency was lower for women as well as for low family income. The sub-abilities of search and synthesis & use were lower for aging consumers. Third, consumer information competency has positive effects on information search efficiency and effectiveness. Moreover, the efficiency influences the effectiveness positively. Fourth, prior knowledge moderates the effect of consumer information competency to the efficiency. Only for consumers with high knowledge the efficiency has the effect of mediating between consumer information competency and the effectiveness.

• Journal of Navigation and Port Research
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• v.29 no.3 s.99
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• pp.195-201
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• 2005

This paper presents the measurement of efficiency for container ports. Data envelopment analysis(DEA), as it is called, has particular applicability in the service sector. Applying mathematical programming techniques, DEA enables relative efficiency ratings to be derived within a set of analysed units. This paper investigates the efficiency employing DEA Model on data for 53 container ports covering 1995-2001 in the world and the change in efficiency for 7 years. As a results, port of Busan was evaluated as inefficiency port compare with major ports of the world except 1995year and 1996year. But After 1997year, efficiency of Busan port is increasing somewhat better every year.

• Geomechanics and Engineering
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• v.20 no.4
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• pp.313-322
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• 2020

This study focuses on a prediction approach of compaction compensation grouting efficiency in sandy soil. Based on Darcy's law, assuming that the grouting volume is equal to the volume of the compressed soil, a two-dimensional calculation model of the compaction compensation grouting efficiency was improved to three-dimensional, which established a dynamic relationship between the radius of the grout body and the grouting time. The effectiveness of this approach was verified by finite element analysis. The calculation results show that the grouting efficiency decreases with time and tends to be stable. Meanwhile, it also indicates that the decrease of grouting efficiency mainly occurs in the process of grouting and will continue to decline in a short time after the completion of grouting. The prediction three-dimensional model proposed in this paper effectively complements the dynamic relationship between grouting compaction radius and grouting time, which can more accurately evaluate the grouting efficiency. It is practically significant to ensure construction safety, control grouting process, and reduce the settlement induced by tunnel excavation.

• Asian Journal of Business Environment
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• v.8 no.2
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• pp.15-22
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• 2018

Purpose - It is important to figure out the relationship between tourism carbon emissions and tourism economics for a healthy tourism development. Research design, data, and methodology - Data of this study are collected from 27 provinces (cities) of China. Tourist consumption stripping coefficient is used to calculate tourism carbon emissions. SBM-Undesirable model is used to measure the efficiency of tourism economics under the constraint of tourism carbon emissions. Results - The results show that: during the year of 2005-2015, there are obvious differences in totals and intensities of tourism carbon emissions among 27 provinces and cities which can be divided into three areas. There is a high possibility of underestimating the actual efficiency of tourism economics by leaving tourism carbon emissions out of account, and a high inefficiency caused by tourism carbon emissions will lead a low efficiency of tourism economics. Conclusions - The development of tourism should give consideration to both economic and environmental benefits, and reduce the inefficiency caused by tourism carbon emissions to improve efficiency of tourism economics by improving the level of technical efficiency and promoting technological progress.