• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.4
• /
• pp.1248-1253
• /
• 2010

In this paper, the compensation algorithm for localization using the concept of equivalent distance rate(AEDR) in order to compensate ranging error in the SDS-TWR(Symmetric Double-Sided Two-Way Ranging) is proposed and the performance of the proposed algorithm is analyzed by the localization experiments. The ranging error of the SDS-TWR in the distance between mobile node and beacon node is measured to average 1m~8m by ranging experiments. But it is confirmed that the performance of the localization by the AEDR is better than that of the SDS-TWR 4 times in university auditorium and corridor, and the localization error of above 3~10m is reduced to average 2m and that of below 3m is reduced to average 1m respectively. It is concluded that the AEDR is superior to the NLOS(Non Line Of Sight) than LOS(Line Of Sight) in performance of ranging compensation for localization, and the AEDR is more helpful to localization systems practically considering the environment of sensor networks is under NLOS.

• Korean Institute of Interior Design Journal
• /
• v.15 no.4 s.57
• /
• pp.123-128
• /
• 2006

The purpose of the research is to estimate the amount of a color image reaction variation by changing areas in order to design the method to reduce an error about the color sample when it is applied in the real situation. The summary of the results acquired in this research is as followed. (1) With fixed observing distance of 1m, we observed that the value and chroma of each color object became higher as sight angle was increased as $2^{\circ},\;10^{\circ},\;and\;30^{\circ}$, even though the variation ratio was different. (2) With fixed sight angle of 10, we observed that the value and chroma of each color object becane higher as observing distance was changed from 1m to 3.3m, even though the variation ratio was different. (3) With same area, we observed that the values and chromas of each color object in the conditions of $1m-30^{\circ}\;and\;3.3m-10^{\circ}$ were almost same. (4) When the area became larger, the subjects tended to feel that colors were bright and clear with the increase of tone. In all the colors, the variation of a color reaction in chroma is higher than those in value. In future, we can observe the limit in applying to colors in the architecture by identifying the tendency of the color change according to the area change qualitatively.

• The Bulletin of The Korean Astronomical Society
• /
• v.44 no.1
• /
• pp.56.2-56.2
• /
• 2019

Measurement of the location of the baryon acoustic oscillation (BAO) feature in the clustering of galaxies has proven to be a robust and precise method to measure the expansion of the Universe. The best constraints so far have been provided from spectroscopic surveys because the errors on the redshift obtained from spectroscopy are minimal. This in turn means that the errors along the line-of-sight are reduced and so one can expect constraints on both angular diameter distance $D_A$ and expansion rate $H^{-1}$. But, future surveys will probe a larger part of the sky and go to deeper redshifts, which correspond to more number of galaxies. Analysing each galaxy using spectroscopy, which is a time consuming task, will not be practically possible. So, photometry will be the most convenient way to measure redshifts for future surveys such as LSST, Euclid, etc. The advantage of photometry is measuring the redshift of vast number of galaxies in a single exposure, but the disadvantage are the errors associated with the measured redshifts. Using a wedge approach, wherein the clustering is split into different wedges along the line-of-sight ${\pi}$ and across the line-of-sight ${\sigma}$, we show that the BAO information can be recovered even for photometric catalogues with errors along the line-of-sight. This means that we can get cosmological distance constraints even if we don't have spectroscopic information.

• Journal of the Korean Society of Safety
• /
• v.28 no.6
• /
• pp.84-89
• /
• 2013

The main causes of traffic accidents can be classified by 3 factors - human error, vehicle deficiency and road environmental problem and most accidents occurs not only 1 factor but combination of 2 or 3-factors. Among these factors, road environmental factor is the most important factor due to influence the behavior of cars and road users and road environmental factor affects 30% of total accidents approximately. The 5 years traffic accidents data analyzed to verify the accidents severity on Korea National Highways. In order to analyze the severity, Ordered Probit Model was used. As a independent variables of this model the number of lane, neighbor road environments, sight distance, vertical grade, lane width, shoulder width and traffic volume were used and as a dependent variables the minor injuries, serious injuries and fatalities were used. Research results shows that sight distance and lane width are identified as significant factors for the traffic accident severity and lesser sight distance and lane width shows greater traffic accident severity.

• Journal of Korean Society of Transportation
• /
• v.32 no.5
• /
• pp.441-451
• /
• 2014

This study proposes a novel performance measure, which is referred to as Hazardous Spacing Index (HSI), to be used for evaluating safety of traffic stream on freeways. The basic principle of the proposed methodology is to investigate whether drivers would have sufficient stopping sight distance (SSD) under limited visibility conditions to eliminate rear-end crash potentials at every time step. Both Road Weather Information Systems (RWIS) and Vehicle Detection Systems (VDS) data were used to derive visibility distance (VD) and SSD, respectively. Moreover, the K-Nearest Neighbors (KNN) method was adopted to predict both VD and SSD in estimating predictive HSIs, which would be used to trigger advanced warning information to encourage safer driving. The outcome of this study is also expected to be used for monitoring freeway traffic stream in terms of safety.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.1
• /
• pp.87-107
• /
• 2015

Considering the localization estimation issue in mixed line-of-sight (LOS)/non-LOS(NLOS) environments based on received signal strength (RSS) measurements in wireless sensor networks, a grid-based correlation method based on the relationship between distance and RSS is proposed in this paper. The Maximum-Likelihood (ML) estimator is appended to further improve the localization accuracy. Furthermore, in order to reduce computation load and enhance performance, an improved recursively version with NLOS mitigation is also proposed. The most advantages of the proposed localization algorithm is that, it does not need any prior knowledge of the propagation model parameters and therefore does not need any offline calibration effort to calibrate the model parameters in harsh environments, which makes it more convenient for rapid implementation in practical applications. The simulation and experimental results evidence that the proposed localization algorithm exhibits good localization performance and flexibilities for different devices.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.9 no.7
• /
• pp.835-840
• /
• 2014

In this paper, we analyze the visual deviation for the sight mismatch between the digital broadcast camera during shooting and panelists due to sideways frequently the digital stopwatch for panelists who participated in the election broadcast to check the time limit. Match the sight of the on-air broadcast camera discussion and participants in the debate, such as the small studio is relatively stable. However, if a large number of participants in the discussion and broadcasting of the forum is a serious sight deviation occurring by sideways large LCD monitor stopwatch that is installed in the center. Therefore, in this paper, the number of panelists, the length of the desk, to discuss the analysis of fair value changes in accordance with the height and distance the distance between the digital stopwatch, and digital broadcast camera.

• 제어로봇시스템학회:학술대회논문집
• /
• 1992.10a
• /
• pp.567-571
• /
• 1992

A guidance loop of the missile system which uses a command to line of sight(CLOS) guidance law is designed based on LQG theory. In the environment of the severe tracking system noise, the system requires small aerodynamic control fin travel and small miss distance simultaneously. Results from a sample airframe shows good performance against a randomly maneuvering target.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.3
• /
• pp.914-919
• /
• 2010

It is confirmed that as the distance measurements accuracy of the SDS-TWR(Symmetric Double-Sided Two-Way Ranging) based on CSS(Chirp Spread Spectrum) is considerably degraded due to frequency interference and it causes to severe errors in the localization applications. In this paper, the compensation algorithm based on error rate offset of distance measurement ($CA_d$) is proposed for the purpose to reduce the ranging errors due to by the SDS-TWR ranging problems. The $CA_d$ measures the distance values between two nodes by means of 1m interval about 1~25m distances in the SDS-TWR, and compensates the distance values using the parameters related to the distance compensation. From the experiments, it is analyzed that the $CA_d$. have reduced the distance error to average 95cm and maximum 526cm, and the distance error by the $CA_d$ was below about 60cm in the 25m distances. In particular, the performance of the distance measurements accuracy by the $CA_d$ is very high in LOS(Line Of Sight) environments.

• Journal of Korean Society of Transportation
• /
• v.6 no.1
• /
• pp.33-41
• /
• 1988

The Wisconsin Department of Transportation currently has a Datalog Information System which facilitates the collection of geometric characteristics at every 0.01 mile high way section. The objectives of this study are to develop the plan and profile drawing of a highway section utilizing the Datalog Information system and to develop a methodology of investigating the safety aspects associated with the highway section being considered. For this purpose, two of the highway design elements, the minimum stoping sight distance as well as passing sight distance based on the AASHTO requirements, were applied in this study. A computer program was also developed to facilitate the data processing activity. The results from the computer program and from a manual analysis which adopted the identical methodology used in the computer program were in a good agreement. a few discrepancies between the two results were due to the data collection error and they were believed to be negligible. Using the computerized methodology developed in this study one does not need the plan and profile drawing to investigate the safety of a highway section, which appears to be an essential progress to the Computer Aided design and Draft in highway engineering field.