• Electronics and Telecommunications Trends
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• v.34 no.5
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• pp.81-90
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• 2019

The data rate for transmission through fiber-optic cables has increased to 400 Gbps in single-wavelength channels. However, speeds up to 1 Tbps are required now to meet the ever-increasing bandwidth demand driven by the diverse requirements of contemporary applications for high-quality on-demand video streaming, cloud services, various social media, and emerging 5G-enabled applications. Because the data rates of the per-channel optical interfaces depend strongly on the operational speed of the optoelectronic devices used in optical transceivers, ultrahigh-speed photonic devices and components, and eventually, chip-level transmitter and receiver technologies, are essentially required to realize futuristic optical transceivers with data rates of 1 Tbps and beyond. In this paper, we review the recent progress achieved in high-speed optoelectronic devices, such as laser diodes, optical modulators, photodiodes, and the transmitter-receiver optical subassembly for optical transceivers in data centers and in metro/long-haul transmission.

• Journal of IKEEE
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• v.27 no.4
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• pp.501-511
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• 2023

This paper introduces and analyzes SAE J2716 SENT (Single Edge Nibble Transmission) protocol, a technical standard for serial transmission of digital sensor data in automotive applications. SENT can transmit both high-speed sensor data and low-speed sensor data in one data frame and has a total of 6 transmission modes, including 3 high-speed channel modes and 3 low-speed channel modes. In this paper, a SENT controller that supports all six modes of the SENT protocol was designed in Verilog HDL, implemented in FPGA, and verified with an oscilloscope and PC.

• International Journal of Highway Engineering
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• v.14 no.6
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• pp.167-173
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• 2012

PURPOSES : This study is to develop speed correction factor for more realistic Level-of-Service(LOS) at multilane highway. METHODS : In this study, we compared speed difference the degree of speed reductions in actual multilane road conditions with speed reduction considering speed correction factor presented in highway capacity manual using statistical techniques. And also we presents new speed correction factor analyzing collected data at national highway No.1 (Goyang~Wolrung). RESULTS : The result of analyzing and comparing new suggested speed correction factor with speed correction factor in Korea Highway Capacity Manual (KHCM) shows RMSE (Root Mean Square Error) in new speed correction factor (RMSE 1.5) is much lower than existing speed correction factor (RMSE 13.4). New suggested speed correction can be used for analyzing Level-of-Service at multilane highway. And also we suggests improvements for analysis procedure in analyzing Level-of-Service at multilane highway CONCLUSIONS : As a result of comparing differences, we draw the causes that effect the differences in speed and suggest new speed correction factor that consider traffic volumes. It can be more rational because it uses speed correction factor which can consider more realistic traffic conditions, etc.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.6788-6798
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• 2015

In recent high speed rail way, the operating speed of train is enhanced and the introduction of EMU train vehicles is increased. In addition, as expected the demand of the concrete slab track and the trend of design cross-section reduction, the clear behavior of evaluation of internal slab layer is demanded about the variation of design load and speed. The purpose of this study is to evaluate and identify the mechanical behavior pattern of concrete slab track and track-road bed with the variation of axle load and train speed. To this end, the behavior of TCL and HSB was evaluated in according to the variation of axle load and speed. And the analysis results and the data measured TCL strain sensor, which was embedded in TCL slab under installation on Honam high speed railway, was analyzed. The analysis result shows that the strain are increasing in according to the speed-up of train, and line regression was obtained from measured data. Analysis data of the state of bonding condition of slab layer and measured data was analyzed. It is conducted that the TCL layer stress of HEMU 430X, which of axle load, is lighter was similar to the stress of KTX-Honam, the standard deviation of measured stress is dramatically increased.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.130-139
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• 2017

The crop damage caused by strong wind was predicted using the wind speed data available from Korean Meteorological Administration (KMA). Wind speed data measured at 19 automatic weather stations in 2012 were compared with wind data available from the KMA's digital forecast. Linear regression equations were derived using the maximum value of wind speed measurements for the three-hour period prior to a given hour and the digital forecasts at the three-hour interval. Estimates of daily maximum wind speed were obtained from the regression equation finding the greatest value among the maximum wind speed at the three-hour interval. The estimation error for the daily maximum wind speed was expressed using normal distribution and Weibull distribution probability density function. The daily maximum wind speed was compared with the critical wind speed that could cause crop damage to determine the level of stages for wind damage, e.g., "watch" or "warning." Spatial interpolation of the regression coefficient for the maximum wind speed, the standard deviation of the estimation error at the automated weather stations, the parameters of Weibull distribution was performed. These interpolated values at the four synoptic weather stations including Suncheon, Namwon, Imsil, and Jangsu were used to estimate the daily maximum wind speed in 2012. The wind damage risk was determined using the critical wind speed of 10m/s under the assumption that the fruit of a pear variety Mansamgil would begin to drop at 10 m/s. The results indicated that the Weibull distribution was more effective than the normal distribution for the estimation error probability distribution for assessing wind damage risk.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.14-17
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• 2005

Global latent heat flux data sets are crucial for many studies such as those related to air-sea interaction and climate variation. Currently, various global latent heat flux data sets are constructed using satellite data. Japanese Ocean Flux data sets with Use of Remote sensing Observations (J-OFURO) includes one of the satellite-derived global latent heat flux data (Kubota et aI., 2000). In this study, we review future development of J-OFURO global latent heat flux data set. In particular, we investigate usage of multi-satellite data for estimating accurate global latent heat flux. Accurate estimation of surface wind speeds over the global ocean is one of key factors for the improved estimation of global latent heat flux. First, we demonstrate improvement of daily wind speed estimation using multi-satellites data from microwave radiometers and scatterometers such as DMSP/SSMI, ERS/AMI, QuikSCAT/SeaWinds, AqualAMSR-E, ADEOS2/AMSR etc. Next, we demonstrate improvement of global latent heat flux estimation using the wind speed data derived from multi-satellite data.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.75-83
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• 2009

Collision behavior of clash cushion occurs for a second of less than 0.4sec usually so that it is too hard to calculate numerically. Therefore, for development of trash cushion, it rely on full-scale vehicle crash test without any design procedure. Occupant safety indices if calculated from acquired data by data measurement system and collision behavior of vehicle and crash cushion is filming using high-speed camera in the crash test. But practical ufo scope of high-speed camera is limited and it is not using to calculated the occupant safety indices or analyzed the energy dissipated mechanism of crash cushion. This work is to estimate to be suitable or not for compare the data from measurement system with the data from high-speed camera. And also it is to grope for practical use scheme to calculation of occupant safety indices or analysis of collision behavior.

• Wind and Structures
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• v.19 no.5
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• pp.467-480
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• 2014

The estimation of wind speed values used in codes and standards is an integral part of the wind load evaluation process. In a number of codes and standards, wind speeds outside of tropical cyclone prone regions are estimated using a single probability distribution developed from observed wind speed data, with no distinction made between the types of causal wind hazard (e.g., thunderstorm). Non-tropical cyclone wind hazards (i.e., thunderstorm, non-thunderstorm) have been shown to possess different probability distributions and estimation of non-tropical cyclone wind speeds based on a single probability distribution has been shown to underestimate wind speeds. Current treatment of non-tropical cyclone wind hazards in worldwide codes and standards is touched upon in this work. Meteorological data is available at a considerable number of United States (U.S.) stations that have information on wind speed as well as the type of causal wind hazard. In this paper, probability distributions are fit to distinct storm types (i.e., thunderstorm and non-thunderstorm) and the results of these distributions are compared to fitting a single probability distribution to all data regardless of storm type (i.e., co-mingled). Distributions fitted to data separated by storm type and co-mingled data will also be compared to a derived (i.e., "mixed") probability distribution considering multiple storm types independently. This paper will analyze two extreme value distributions (e.g., Gumbel, generalized Pareto). It is shown that mixed probability distribution, on average, is a more conservative measure for extreme wind speed estimation. Using a mixed distribution is especially conservative in situations where a given wind speed value for either storm type has a similar probability of occurrence, and/or when a less frequent storm type produces the highest overall wind speeds. U.S. areas prone to multiple non-tropical cyclone wind hazards are identified.

• Smart Structures and Systems
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• v.21 no.5
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• pp.601-609
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• 2018

The estimated probabilistic model of wind data based on the conventional approach may have high discrepancy compared with the true distribution because of the uncertainty caused by the instrument error and limited monitoring data. A sequential quadratic programming (SQP) algorithm-based finite mixture modeling method has been developed in the companion paper and is conducted to formulate the joint probability density function (PDF) of wind speed and direction using the wind monitoring data of the investigated bridge. The established bivariate model of wind speed and direction only represents the features of available wind monitoring data. To characterize the stochastic properties of the wind parameters with the subsequent wind monitoring data, in this study, Bayesian inference approach considering the uncertainty is proposed to update the wind parameters in the bivariate probabilistic model. The slice sampling algorithm of Markov chain Monte Carlo (MCMC) method is applied to establish the multi-dimensional and complex posterior distribution which is analytically intractable. The numerical simulation examples for univariate and bivariate models are carried out to verify the effectiveness of the proposed method. In addition, the proposed Bayesian inference approach is used to update and optimize the parameters in the bivariate model using the wind monitoring data from the investigated bridge. The results indicate that the proposed Bayesian inference approach is feasible and can be employed to predict the bivariate distribution of wind speed and direction with limited monitoring data.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.485-490
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• 1999

Wind vector information over the ocean is currently obtained using multiple beam scatterometer data. The scatterometers on ERS-1/2 generate wind vector information with a spatial resolution of 50km and accuracies of $\pm$2m/s in wind speed and $\pm$20$^{\circ}$ in wind direction. Synthetic aperture radar (SAR) data over the ocean have the potential of providing wind vector information independent of weather conditions with finer resolution. Finer resolution wind vector information can often be useful particularly in coastal regions where the scatterometer wind information is often corrupted because of the lower resolution system characteristics which is often contaminated by the signal returns from the coastal areas or ice in the case of arctic environments. In this paper we tested CMOD_4 and CMOD_IFR2 algorithms for extracting the wind vector from SAR data. These algorithms require precise estimation of normalized radar cross-section and wind direction from the SAR data and the local incidence angle. The CMOD series algorithms were developed for the C-band, VV-Polarized SAR data, typically for the ERS SAR data. Since RADARSAT operates at the same C-band but with HH-Polarization, the CMOD series algorithms should not be used directly. As a preliminary approach of resolving with this problem, we applied the polarization ratio between the HH and VV polarizations in the wind vectors estimation. Two test areas, one in front of Inchon and several sites around Jeju island were selected and investigated for wind vector estimation. The new results were compared with the wind vectors obtained from CMOD algorithms. The wind vector results agree well with the observed wind speed data. However the estimation of wind direction agree with the observed wind direction only when the wind speed is greater than approximately 3.0m/s.