• 한국태양에너지학회:학술대회논문집
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• 2008.11a
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• pp.288-293
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• 2008

A predictive model of wind speed in the wind farm has very important meanings. This paper presents an estimation model of wind speed based on time series analysis using the observed wind data at Hangyeong Wind Farm in Jeju island, and verification of the predictive model. In case of Hangyeong Wind Farm and Haengwon Wind Farm, The ARIMA(Autoregressive Integrated Moving Average) predictive model was appropriate, and the wind speed estimation model was developed by means of parametric estimation using Maximum likelihood Estimation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.1
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• pp.35-40
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• 2015

This paper presents the optimal network configuration for electric stations using HOMER software. For the given data such as annual average wind speed and grid costs, this software calculates the NPC(Net Present Cost), operating cost and COE(Cost of Energy). Based on these simulation results, it is possible to find the optimal network configuration for electric stations depending on the grid cost and average wind speed. When the rising grid cost is considered, it is essential to use grid and renewable energy together. Depending on the increase of the grid cost, NPC of the configuration using renewable energy and grid can be gradually getting smaller than NPC of the configuration using only grid.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.3
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• pp.197-202
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• 2008

In this paper, we proposed an analytical model for TFT which has series of the polycrystalline structures. An average speed is defined as carrier speed by the electric field. The effective square is suggested as the area of grain without depletion for the changed grain size. First, physical parameters such as grain size, channel lenght and trap density, have been changed to prove the validity of the average speed model and the value of the effective square has been estimated through drain-source current.

• Journal of the Korean Society of Safety
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• v.34 no.1
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• pp.90-97
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• 2019

This study is aiming to compare stair ascent transportation speed and physical burden of evacuation supporters according to the types of stair ascent transportation for vulnerable people experimentally. In this study, we measured heart rate of the supporters to indicate physical burden during the transportation. The subjects of this experiment were male students, age of 20-26. Experimental conditions were the ways of stair transportation and the weight of vulnerable people. The types of stair transportation were giving a piggyback ride and carrying a wheelchair. Each experimental trial was video-recorded for measurement of ascent speed and observing supporters movement. As a result of the experiment, as for the ascent transportation speed by piggyback ride from the first floor to the fourth floor, the average speed of the light case is 31 seconds and for the heavy case is 43 seconds. When it comes to the average speed of wheelchair transportation's average speed the light case is 1 minute and 11 seconds and the heavy case is 1 minute and 49 seconds. Therefore, it was indicated that when the weight of a vulnerable people is lighter, the transportation speed is faster. The heart rates of evacuation supporters are different depending on transportation methods or individual's condition but as repetitive transportation increases, they tend to reach the maximum heart rates.

• Journal of Korean Society of Forest Science
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• v.99 no.2
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• pp.197-203
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• 2010

The data of average temperature, average relative humidity, precipitation and average wind speed were collected from 674 meteorological stations in China. A specific procedure that processes original data into a new data format needed in forest fire danger rating forecast system of China was introduced systematically, and the feasibility of this method was validated in this paper. In addition, a set of meteorological data processing software was constructed by the secondary development of GIS in order to realize automation of processing data for the system. Results showed that the approach preformed well in handling temperature, average relative humidity and average wind speed, and the processing effect of precipitation was acceptable. Moreover, the automated procedure could be achieved by GIS and the working efficiency was about 3 times as much as that of manual handling. The informationization level of processing meteorological data was greatly enhanced.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.3 no.1
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• pp.66-71
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• 2003

In the past, when there were few vehicles on the road, the T.O.D.(Time of Day) traffic signal worked very well. The T.O.D. signal operates on a preset signal cycling which cycles on the basis of the average number of average passenger cars in the memory device of an electric signal unit. Today, with increasing traffic and congested roads, the conventional traffic light creates startup-delay time and end lag time so that thirty to forty-five percent efficiency in traffic handling is lost, as well as adding to fuel costs. To solve this problem, this paper proposes a new concept of optimal green time algorithm, which reduces average vehicle waiting time while improving average vehicle speed using fuzzy rules and neural networks. Through computer simulation, this method has been proven to be much more efficient than fixed time interval signals. Fuzzy Neural Network will consistanly improve average waiting time, vehicle speed, and fuel consumption.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.183-190
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• 2012

PURPOSES : The fundamental diagram provides basic information necessary in the analysis of traffic flow and highway operation. When traffic flow is congested, the density-flow points in the fundamental diagram are widely scattered and move in a stochastic manner. This paper investigates the pattern of density-flow point transitions and identifies car-following behaviors underlying the density-flow transitions. METHODS : From a microscopic analysis of 722 fundamental diagrams of NGSIM data, a total of 20 transition patterns of fundamental diagrams are identified. Prominent features of the transition patterns are explained by the behavior of the leader and follower. RESULTS : It is found out that the average speed and the speed difference between the leader and the follower critically determine the density-flow transition pattern. The density-flow path is very sensitive to the values of vehicle speed and spacing especially at low speed and high density such that most fluctuations in the fundamental diagram in the congested regime is due to the noise of speed and spacing variations. CONCLUSIONS : The result of this study suggests that the average speed, the speed difference between the leader and the follower, and the random variations of speed and spacing are dominant factors that explain the transition patterns of a fundamental diagram.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.4
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• pp.599-620
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• 2017

In this study, we analyzed how the speed concept has been handled in Korean elementary mathematics textbooks and suggested some didactical implications for revising the teaching of speed concept. To do this, we investigated the curriculum documents, textbooks and teacher's manuals from the first curriculum to the 2009 revision curriculum. The results show that the speed concept of the elementary mathematics in Korea has been based on the concept of average speed and that the approach of applying the value of ratio has been strengthening more than the aspect of proportional relation. So we suggested two didactical suggestions: 1) the teaching of the speed concept should start with uniform movements. 2) the reasoning of proportional relation should be more strengthened.

• Journal of Korean Port Research
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• v.14 no.1
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• pp.66-75
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• 2000

From the traffic analysis, and model constructions and verifications for speed prediction on the freeway ramp junctions with 70mph speed limit, the following results were obtained : ⅰ) The traffic flow distribution showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy distribution was also shown to be varied by a big difference depending on the time periods. Especially, the occupancy in the morning peak period showed over 100% increase when compared with the 24hours average occupancy, and the occupancy in the afternoon peak period over 25% increase when compared with the same occupancy. ⅲ) The speed distribution was not shown to have a big difference depending on the time periods. Especially, the speed in the morning peak period showed 10mph decrease when compared with the 24hours'average speed, but the speed did not show a big difference in the afternoon peak period. ⅳ) The analyses of variance showed a high explanatory power between the speed predictive models(SPM) constructed and the variables used, especially the upstream speed. ⅴ) The analysis of correlation for verifying the speed predictive models(SPM) constructed on the ramp junctions were shown to have a high correlation between observed data and predicted data. Especially, the correlation coefficients showed over 0.95 excluding the unstable condition on the diverge section. ⅵ) Speed predictive models constructed were shown to have the better results than the HCM models, even if the speed limits on the freeway were different between the HCM models and speed predictive models constructed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1999.10a
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• pp.111-121
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• 1999

From the traffic analyses, and model constructions and verifications for speed prediction on the freeway ramp junctions with 70mph speed limit, the following results obtained: ⅰ) The traffic flow distribution showed a big difference depending on the time periods. Especially, more traffic flows were concentrated on the freeway junctions in the morning peak period when compared with the afternoon peak period. ⅱ) The occupancy distribution was also shown to be varied by a big difference depending on the time periods. Especially, the occupancy in the morning peak period showed over 100% increase when compared with the 24hours average occupancy, and the occupancy in the afternoon peak period over 25% increase when compared with the same occupancy.ⅲ) The speed distribution was not shown to have a big difference depending on the time periods. Especially, the speed in the morning peak period shown 10mph decrease when compared with the 24hours' average speed, but the speed did not show a big difference in the afternoon peak period.ⅳ) The analyses of variance showed a high explanatory power between the speed predictive models(SPM) constructed and the variables used, especially the upstream speed. ⅴ) The analysis of correlation for verifying the speed predictive models(SPM) constructed on the ramp junctions were shown to have a high correlation between observed data and predicted data. Especially, the correlation coefficients showed over 0.95 excluding the unstable condition on the diverge sectionⅵ) Speed predictive models constructed were shown to have the better results than the HCM models, even if the speed limits on the freeway were different between the HCM models and speed predictive models constructed.