• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.356-361
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• 1996

Nowadays, Electronic Speckle Pattern Interferometry is a well established measuring technique with a wide range of industrial applications, particularly in the fields of deformation measurement and vibration analysis. Comparing with holographic inteferometry, it has some attractive features, which are rapid recording and reconstruction, satisfiable automation etc. Time-average ESPI was used to provide vibration mode shape of an object whose vibration amplitude is given as a fringe pattern. However, it is not possible to determine the direction of motions of a point on the object at any given time, because time-average method does not give any information about the phase of vibration. A better technique is stroboscopic method which can measure the amplitude and phase of vibrating surface. In this paper, loudspeakers were tested by these two methods and the mode shape and amplitude of vibration were visualized. As measured results, we can assume that these techniques will be applied directly in the loudspeaker industry.

• Communications for Statistical Applications and Methods
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• v.25 no.1
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• pp.91-97
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• 2018

In this paper, we show that there exists an optimal investment policy for the surplus in a risk model, in which the surplus is continuously invested to other business at a constant rate a > 0, whenever the level of the surplus exceeds a given threshold V > 0. We assign, to the risk model, two costs, the penalty per unit time while the level of the surplus being under V > 0 and the opportunity cost per unit time by keeping a unit amount of the surplus. After calculating the long-run average cost per unit time, we show that there exists an optimal investment rate $a^*$>0 which minimizes the long-run average cost per unit time, when the claim amount follows an exponential distribution.

• Journal of the Korean housing association
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• v.19 no.4
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• pp.97-105
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• 2008

The purposes of this study were to determine the actual state of the indoor thermal environment in apartment units and to analyze the relationship between the living factors and indoor thermal elements. The field surveys consisted of measurements of physical elements and observations of living factors. In addition, the residents of 20 apartment units were interviewed to survey their subjective response. Field surveys were carried out from January to March 2007. Measuring elements were air temperature, globe temperature, and relative humidity. The results showed that the average of indoor temperature for the houses was $21.2{\sim}27.2^{\circ}C$, while 4 houses exceeded the comfort zone. The average of globe temperature for the houses was $21.3{\sim}27.5^{\circ}C$, while 6 houses exceeded the comfort zone. The mean relative humidity was $19.5{\sim}58.8%$, which is a relatively dry condition. The residents' average clothing value was $0.39{\sim}0.89$ clo(average 0.68 clo). The average thermal sensation vote on each room was $4.2{\sim}4.8$, which is 'neutral' to 'slightly warm'. Living factors had significant effect on indoor temperature in regression analysis were ventilation time(outdoor air exchange), opening time of door through balcony, and gas cooker use time.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.4
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• pp.23-30
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• 2022

Recently, traffic congestion and environmental pollution have occurred due to population concentration and vehicle increase in large cities. Various studies are being conducted to solve these problems. Most of the traffic congestion in cities is caused by traffic signals at intersections. This paper proposes a dynamic traffic light control (DTLC) scheme to support safe vehicle operation and smooth traffic flow using real-time traffic information based on VANET. DTLC receives instantaneous speed and directional information of each vehicle through road side units (RSUs) to obtain the density and average speed of vehicles for each direction. RSUs deliver this information to traffic light controllers (TLCs), which utilize it to dynamically control traffic lights at intersections. To demonstrate the validity of DTLC, simulations were performed on average driving speed and average waiting time using the ns-2 simulator. Simulation results show that DTLC can provide smooth traffic flow by increasing average driving speed at dense intersections and reducing average waiting time.

• Journal of Korean Society of Transportation
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• v.20 no.3
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• pp.159-168
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• 2002

The Highway Capacity Manual(HCM) suggests estimating the average green time for the performance evaluation of the traffic actuated operation and Provides the average green time estimation model. However, the model provides with much room for improvements. This document proposes a new analytical model that overcomes the shortage of the HCM model. The average green times estimated by the HCM model and the proposed model were compared. A computer program using the proposed model was coded for the study, while the ACT348 program was used for the implementation of the HCM model Through the comparison study based on the 1,196 hypothetical simulation data surrogating field data, it was found that the average green times estimated by the proposed model yields much nicer one-to-one linear relationship to the simulation results than the ones from the HCM model in both exclusive-only and shared-permitted cases. The R2 values of the proposed and the HCM models with those cases are 0.90 and 0.56, and 0.86 and 0.57, respectively.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2078-2081
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• 2003

This paper presents the studies on prediction models of tropospheric scintillation. The prediction scintillation models are Karasawa and ITU-R , which can be improved for different locations and circumstances. In this paper, the investigation of average time between variance ${\sigma}_n\;^2$ and the wet part of refractivity $N_{wet}$ under various conditions of meteorological parameters have been carried out at King Mongkut’s Institute of Technology Lankrabang , Bangkok , Thailand , in the range of Ku-band (12.260 GHz) on high elevation angle from Thaicom2 satellite. From the studies results shows that average period of time of 30 days are best suitable for find out the relation between average time variance ${\sigma}_n\;^2$ and the wet part of refractivity $N_{wet}$ according to Karasawa model, the average time variance is express as ${\sigma}_n\;^2=(0.003N_{wet}-0.1313)^2$ , the appropriation model for occurrence of scintillation has been analyzed and experimental results are carried out.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.159-167
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• 2013

PURPOSES : In this study, the effects of when median exclusive bus lanes were applied to Daejeon trunk road (Wolpyeng crossway~Seodaejeon crossway, 6.3km) and (Daeduck Bridge 4~Kyeryong 4, 2.6km) by Microscopic Simulation VISSIM (5.0) was studied. The median exclusive bus lanes are one of the measures of transportation system manage techniques that can especially improve the efficiency of public transportation facilities. METHODS : According to the analysis of VISSIM on the Gyerong mainroad and Daedeok mainroad, when the median exclusive bus lanes were applied unlike when the roadside bus-only lanes were applied, the average travel speed of vehicles decreased but the average delay time and travel time increased. This arised from the changes in the geometric structure of the road which occurred the reduction of vehicle lane in the center of the road. RESULTS : In the case of bus, on the other hand, the average travel speed increased but the average delay time and travel time decreased. This is because the problems such as illegal parking and stopping, secondary road in out vehicle, and conflict of intersection right turn that roadside bus-only lanes occurred was solved. CONCLUSIONS : Although the introduction of median exclusive bus lanes will have a negative effect on general traffic flow due to the aggravation of travel, decrease of passenger car usage will lead to decrease of traffic volume. Therefore, smooth vehicle travel is expected.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4349-4371
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• 2019

Moldable parallel tasks are widely used in different areas, such as weather forecast, biocomputing, mechanical calculation, and so on. Considering the deadline and the speedup, scheduling moldable parallel tasks becomes a difficulty. Past work majorly focuses on the LA (List Algorithms) or OMA (Optimizing the Middle Algorithms). Different from prior work, our work normalizes execution time and makes all tasks have the same scope in normalized execution time: [0,1], and then according to the normalized execution time, a method is used to search for the reference execution time without considering the deadline of tasks. According to the reference execution time, we get an initial scheduling result based on AFCFS (Adaptive First Comes First Served) policy. Finally, a heuristic approach is used to improve the performance of the initial scheduling result. We call our method HSRET (a Heuristic Scheduling method based on Reference Execution Time). Comparisons to other methods show that HSRET has good performance in AWT (Average Waiting Time), AET (Average Execution Time), and PUT (Percentages of Unfinished Tasks).

• Journal of Korean Elementary Science Education
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• v.39 no.1
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• pp.133-144
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• 2020

The purpose of this study is to identify the effect of Teacher Participation-oriented Education Program (TPEP) for Elementary School Teachers to Improve Class Expertise in Science Classes with a focus on visual attention. The participants were two elementary school teachers in Seoul and taught science subjects. The lesson topic applied to this study were 'Structure and Function of Our Body' in the second semester of fifth grade and 'Volcano and Earthquake' in the second semester of fourth grade. The mobile eye tracker SMI's ETG 2w, which is a binocular tracking system was used in this study. In this study, the actual practice time, participant's visual attention, visual intake time average, and visual intake time average were analyzed by class phase. The results of the study are as follows. First, as a result of analyzing the actual class execution time, the actual class execution time was almost in line with the lesson plan after the TPEP application. Second, visual attention in the areas related to teaching and learning activities was high after applying TPEP. Factors affecting the progress of the class and cognitive burdens were identified quantitatively and objectively through visual attention. Third, as a result of analyzing the visual intake time average of participants, there was a statistically significant difference in all classes. Fourth, as a result of analyzing the visual intake time average of participants, the results were statistically significant in the introduction(video), activity 1, activity 2, and activity 3 stages in the lecture type class. The Teacher Participation-oriented Education Program (TPEP) for Elementary School Teachers to Improve Class Expertise in Science Classes can extend elementary science class expertise such as self-class analysis, eye tracking, linguistic, gesture, and class design beyond traditional class analysis and consulting.

• Journal of Korean Library and Information Science Society
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• v.54 no.1
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• pp.221-240
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• 2023

This study proposes a medium-specific reading instruction method for digital natives exposed to various reading media with the development of information and communication technology. For this purpose, an elementary school located in H-si, Gyeonggi-do was selected and the readability and literacy tests according to the media were conducted for 6th graders. In the experiment, the same article contents were divided into three groups, and the time required to read and read using different media was measured, and the literacy according to the media was confirmed through quizzes. As a result of the measurement, the average reading time of the web-page was 3 minutes 28 seconds, the quiz correct answer rate (average) 3.99 questions, the average reading time of the pdf file in the form of an e-book was 5 minutes 23 seconds, the correct answer rate (average) 4.35 questions, the average reading time of the printed text was 7 minutes 14 seconds, and the correct answer rate (average) 6.26 questions. The number of students who participated in the experiment is 144, and there is a limit to generalizing the reading method according to the media type only with the results of the researcher's experiment.