• Journal of the Korean Data and Information Science Society
• /
• v.24 no.6
• /
• pp.1211-1219
• /
• 2013

Recently, the usage of skew-normal distribution, instead of classical normal distribution, is rising up in many statistical theories and applications. In this paper, we deal with saddlepoint approximation for the distribution function of sample mean of skew-normal distribution. Comparing to normal approximation, saddlepoint approximation provides very accurate results in small sample sizes as well as for large or moderate sample sizes. Saddlepoint approximations related to the skew-normal distribution, suggested in this paper, can be used as a approximate approach to the classical method of Gupta and Chen (2001) and Chen et al. (2004) which need very complicate calculations. Through simulation study, we verified the accuracy of the suggested approximation and applied the approximation to Robert's (1966) twin data.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.12A
• /
• pp.1207-1213
• /
• 2010

In this paper, we proposed analysis additional data transmission scheme based on T-DMB system with watermarking technique for emergency broadcasting service. By applying the proposed scheme to T-DMB system, it allows additional data transmission and improves spectral efficiency of data transmission through watermarking spreading code. In the emergency situation, we can react the emergency situation using the emergency information that generated by proposed scheme. We are certified availability of our proposed technology by using various simulation. The performance is evaluated in terms of bit error rate (BER). From the simulation result, we confirmed the performance of T-DMB system embedded watermarking scheme and it is shown that system performance is affected the watermarking level. The results of the paper can be applied to wireless multimedia digital broadcasting system.

• Journal of Korean Society of Disaster and Security
• /
• v.12 no.4
• /
• pp.53-61
• /
• 2019

Occurrences of debris flow are a serious danger to roads and residential located in mountainous areas and cause a lot of property loss. In this study, two basins were selected and spatial data were constructed to simulate the occurred debris flow from mountainous areas. The first basin was to use the Terrestrial LiDAR to scan the debris flow occurrence section and to build terrain data. For the second basin, use drones the sediment in the basin was photographed and DSM (Digital surface model) was generated. And to analyze the effect of the occurrence of debris flow on downstream side, FLO-2D, two-dimensional commercial model, was used to simulate the flow region of the debris flow. And it was compared with the sedimentation area of terrestrial LiDAR and drone measurement data.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.8 no.6
• /
• pp.534-543
• /
• 2015

This paper proposes an Energy Theft Traceback Protocol(ETTP) based on Logging and Marking that can trace Energy Theft back in Smart Grid Environment. The ETTP consists of the following three phases. First, it classifies Energy Theft Type into Measurement Rejection and Data Fabrication by generating an Energy Theft Tree. Second, it detects an Energy Theft by using the Energy Theft Tree. Finally, it trace an Energy Theft back by using the Logging Table of a Router and the Marking Information of a Packet. The result of its simulation shows that the Detection Ratio of Energy Theft is estimated at 92% and the Success Ratio of Energy Theft Traceback at 93%. Therefore, the ETTP not only reduces such risk factors as Forgery and Tampering about Billing information but also provides safe and reliable Smart Grid environment.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.5C
• /
• pp.302-308
• /
• 2011

In this paper we propose a coordinated beamforming(CBF) scheme considering the effects of feedback quantization and delay in time-varying multiple-input multiple-output(MIMO) broadcast channels. By equal power allocation per data stream, the proposed CBF scheme transmits multiple data streams per user terminals without additional feedback overhead when quantized feedback information is used. The proposed CBF scheme also applies a linear channel predictor to each user terminals to prevent errors due to feedback delays that are not evitable in practical wireless systems. Each user terminal utilizes Wiener filter to predict future channel responses and generates feedback information based on the predicted channels. Consequently the proposed CBF scheme adapting Wiener filter improves system performances compared with the conventional scheme using delayed feedback.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.3
• /
• pp.510-518
• /
• 2014

In this study, in order to improve and optimize the performance of the turning mechanism for a fish robot in the fluid, we propose the tail joint trajectories using neural networks to mimic the CST(C-shape Sharp Turn) patterns of a real fish which is optimized in the natural environment. In order to mimic the CST patterns of a fish, we convert the sequential recording CST patterns into the coordinate data, and change the numerical coordinate data into a functions. We change the motion functions to the relative joint angles which is adapted to suit robot's shape and data. However, these relative joint trajectories obtained by the sequential recording of the carp have low-precision. It is difficult to apply to the control of a fish robot. Therefore, the relative joint trajectories are interpolated using neural networks with superior generalization ability and applied to the fish robot. we have found that the proposed method using neural networks is superior to ones using high-order polynomial equation through the computer simulations.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.4
• /
• pp.569-574
• /
• 2018

This paper proposes and implements a LoRa-based emergency exit guide system which can direct the optimal refuge path accounting for the real state of the fires. Each 4-way emergency exit guide sign presents a right direction through one of four LED signs toward the possible exit dynamically calculated by the shortest path algorithm. We constructed a simulation environment with 8 spots of the emergency exit guide signs and 2 exits, which can simulate variant cases of fire accidents, and showed that the proposed algorithm can presents the right guidance for each emergency exit guide sign. We also evaluated the performances of LoRa-based wireless communications using a self developed communication module in the various indoor and outdoor environments. The proposed system can be applied to small and medium sized buildings as well as larger ones in terms of cost efficiency, in which there's no needs to invest for the complex equipments except only sensors and emergency exit guide signs.

• Journal of Satellite, Information and Communications
• /
• v.9 no.2
• /
• pp.74-79
• /
• 2014

Conventional ScanSAR mode has been adopted in Envisat or Radarsat and played an important role to acquire wide swath SAR images for environmental surveillance. However, it suffers from the undesirable scalloping effect caused by non-homogeneity of antenna pattern while the image resolution is sacrificed. In recent years, TOPS mode has been suggested and put into use to overcome the disadvantages of the conventional scanning mode. Although TOPS mode is able to produce wide-swath SAR image in a short time interval, it demands highly complicated system design knowledge. In this paper, we present the operation principle of TOPS mode and a full SAR simulation is performed to generate TOPS SAR raw data. Azimuth antenna pattern is modified during TOPS mode operation and it is shown that the undesired scalloping effect is suppressed in the generated SAR image.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.9
• /
• pp.6305-6314
• /
• 2015

This study presents numerical simulations of mean flow and turbulence structure of an open channel with submerged vegetation. Filtered Navier-Stokes equations are solved using large-eddy simulation (LES). The immersed boundary method (IBM) is employed based on a Cartesian grid. The numerical result is compared with experimental data of Liu et al. (2008) and shows that simulated results coincided reasonably with experimental data within the average error of 10%. Strong vortices are generated at the interface between vegetated and non-vegetated regions with spanwise extent. The generation of turbulence induced by shear at the interface is interfered with wake turbulence, resulting turbulence intensity maximum. Turbulence produced by shear affects the flow in vegetated region and the penetration depth increases with an increase in the submergence ratio. This result can be used to understand sediment transport mechanisms in the vegetated region.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.21 no.6
• /
• pp.163-171
• /
• 2021

In this paper, the energy transaction system was optimized by applying a resource allocation algorithm and deep reinforcement learning in the distributed power system. The power demand and supply environment were predicted by deep reinforcement learning. We propose a system that pursues common interests in power trading and increases the efficiency of long-term power transactions in the paradigm shift from conventional centralized to distributed power systems in the power trading system. For a realistic energy simulation model and environment, we construct the energy market by learning weather and monthly patterns adding Gaussian noise. In simulation results, we confirm that the proposed power trading systems are cooperative with each other, seek common interests, and increase profits in the prolonged energy transaction.