• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.705-706
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• 2014

This paper proposes a new dynamic bandwidth allocation algorithm for an XG-PON (10-Gbps-capable passive optical network) system. In the XG-PON system, an ONU (optical network unit) does not explicitly send it request to an OLT (optical line termination). The OLT monitors the upstream bandwidth usage of the ONU to estimate the request of the ONU. Then the OLT performs a dynamic bandwidth allocation process based on the estimated requests.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.152-153
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• 2014

This paper proposes a new dynamic bandwidth allocation algorithm for an XG-PON (10-Gbps-capable passive optical network) system in which an ONU (optical network unit) does not explicitly send its request to an OLT (optical line termination). To estimate the request of the ONU, the OLT monitors the upstream bandwidth usage of the ONU and periodically allocates a probe slot to the ONU.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.435-446
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• 2022

Identifying ship types is an important process to prevent illegal activities on territorial waters and assess marine traffic of Vessel Traffic Services Officer (VTSO). However, the Terrestrial Automatic Identification System (T-AIS) collected at the ground station has over 50% of vessels that do not contain the ship type information. Therefore, this study proposes a method of identifying ship types through the Random Forest Classifier (RFC) from dynamic and static data of AIS and V-Pass for one year and the Ulsan waters. With the hypothesis that six features, the speed, course, length, breadth, time, and location, enable to estimate of the ship type, four classification models were generated depending on length or breadth information since 81.9% of ships fully contain the two information. The accuracy were average 96.4% and 77.4% in the presence and absence of size information. The result shows that the proposed method is adaptable to identifying ship types.

• Journal of Korean Institute of Industrial Engineers
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• v.14 no.1
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• pp.1-15
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• 1988

DS1 transmission systems use framing bit errors, bipolar violations and code-detected errors to estimate the bit error rate when determining errored and severely errored seconds. Using the coefficient of variation under the memoryless binary symmetric channel assumption, a basic framework to evaluate these estimation schemes is proposed to provide a practical guideline in determining errored and severely errored seconds which are fundamental in monitoring the real-ime error performance of DS1 transmission systems carrying live traffic. To evaluate the performance of the cyclic redundancy check code (CRC), a computer simulation model is used. Several drawbacks of the superframe format in association with real time error performance monitoring are discussed. A few recommendations are suggested in measuring errored and severely errored seconds, and determining service limit alarms through the use of the superframe format. Furthermore, we propose a new robust scheme for determining service limit alarms which take into consideration the limitations of some estimation schemes for the time interval of one second.

• Journal of Environmental Health Sciences
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• v.25 no.3
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• pp.94-102
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• 1999

To estimate the effects of environmental noise on inhabitants' life in an apartment area at Taejon, noise levels and traffic volume of major roads were measured. 203 housewives were surveyed by questionaires including general factors, noise related factors and three items of life effects: subjective evaluations on the general environment, annoyance, and life disturbance due to environmental noise. At the boundary adjacent to the road with more traffic volume, noise level was higher; according to the time, the amount of noise level was in the morning, in the evening, at noon, and at night in order. Most of boundary noise levels were higher than those of recommended standard environmental noise levels in a residential area. The boundary noise level showed a very significant linear relationship with traffic volume of near roads. Noise level difference in the apartments adjacent to three roads was ranged 2.4~6.7dB between in windows open and close state. The apartments adjacent to 9 lane or 6 lane-road, which were protected by noise prevention wall and 20m or more distance from the roads, showed higher noise level at middle floors and high floors than those of low floors; but the buildings adjacent to 4 lane-road, with no protection, showed higher noise level at low and middle floors than those of high floors. Among 203 housewives, 120(59.1%) participated in this study, and 86(73.2%) of them answered that the most serious environmental noise was traffic noise from near roads. Comparing traffic noise levels with those of before-migration, 67.0% participants found the environmental noise became louder. Fifty eight(49.5%) of the participants wanted noise protection wall and 15(25.9%) of them were willing to charge the fee. Less perception on the present noise comparing to those before-migration, less traffic volume, and lower noise levels in the apartments were related to higher scores of self-evaluation on the environment. Higher susceptibility on the present noise, areas with more traffic volume, higher boundary noise levels, and higher noise levels showed higher scores of annoyance on environmental noise and life disturbance. Considering above all things, it was suggested that traffic noise in this area was the major problem of environmental noise, and its' effect was so serious that inhabitants needed some preventive measures for better life quality.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.5 no.1 s.9
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• pp.1-12
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• 2006

In order to estimate a dynamic origin and destination demand between on and off-ramps in the freeways, a traffic flow theory can be used to calculate a link distribution proportion of traffics moving between them. We have developed a dynamic traffic estimation model based on the three-phase traffic theory (Kerner, 2004), which explains the complexity of traffic phenomena based on phase transitions among free-flow, synchronized flow and moving jam phases, and on their complex nonlinear spatiotemporal features. The developed model explains and estimates traffic congestion in terms of speed breakdown, phase transition and queue propagation. We have estimated the link, on and off-ramp volumes at every time interval by using traffic data collected from vehicle detection systems in Korea freeway sections. The analyzed results show that the developed model describes traffic flows adequately.

• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.220-233
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• 2017

Traffic volumes are fundamental data widely used in various traffic analysis, such as origin-and-destination establishment, total traveled kilometer distance calculation, congestion evaluation, and so on. The low number of links collecting the traffic-volume data in a large urban highway network has weakened the quality of the analyses in practice. This study proposes a method to estimate the traffic volume data on a highway link where no collection device is available by introducing a spatial statistic technique with (1) the traffic-volume data from TOPIS, and National Transport Information Center in the Ministry of Land, Infrastructure, and (2) the navigation data from private navigation. Two different component models were prepared for the interrupted and the uninterrupted flows respectively, due to their different traffic-flow characteristics: the piecewise constant function and the regression kriging. The comparison of the traffic volumes estimated by the proposed method against the ones counted in the field showed that the level of error includes 6.26% in MAPE and 5,410 in RMSE, and thus the prediction error is 20.3% in MAPE.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.1161-1164
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• 2005

In this paper, we proposed the technique to estimate the life cycle of Internet content services based on the logistic regression model. In this paper, to define parameters of Internet contents estimating life cycle by logistic regression model, we used market size, traffic amount, page view and session-visit number as the parameters of Internet contents estimating life cycle by logistic regression model. In this paper, to compare the performance of our proposed scheme, we estimated life cycle for the download services of bell sound & character contents in mobile network. As a result, using our proposed logistic regression, we were able to estimate exactly the life cycle of the download services of bell sound & character contents.

• Communications for Statistical Applications and Methods
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• v.21 no.5
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• pp.387-393
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• 2014

Recurrent gap times are analyzed with diverse methods under several assumptions such as a marginal model or a frailty model. Several resampling techniques have been recently suggested to estimate the covariate effect; however, these approaches can be applied with a time-fixed covariate. According to simulation results, these methods result in biased estimates for a time-varying covariate which is often observed in a longitudinal study. In this paper, we extend a resampling method by incorporating new weights and sampling scheme. Simulation studies are performed to compare the suggested method with previous resampling methods. The proposed method is applied to estimate the effect of an educational program on traffic conviction data where a program participation occurs in the middle of the study.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.271-272
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• 2008

TD-SCDMA combines TDMA and CDMA components to provide more efficient use of radio resources, and includes a new feature called HSDPA (high-speed downlink packet access) in the R5 stage. The TD-HSDPA supports high-speed traffic with a shared channel, but its uplink mechanism causes feedback problem for scheduling. Since the base station of TD-SCDMA can estimate the location of mobile terminals precisely, it can also estimate the possible path loss. In this paper, the base station utilizes the estimated path loss for scheduling, which is related with CQI (channel quality indicator) values. The proposed mechanism can provide the TD-HSDPA scheduler with an intial CQI value for efficient transmission.