• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.534-543
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• 2015

This paper introduces the time-misalignment error between multiple range measurements acquired by an onboard distance measuring equipment (DME) interrogator and proposes an efficient position determination method that can mitigate the negative effects of the time-misalignment error. The introduced time-misalignment error does not occur in conventional utilization of DME combined with VHF omnidirectional range (VOR). The proposed position determination method projects all the DME range measurements acquired irregularly during an interval to the same time instance where the aircraft position is determined. By the simulation utilizing a representative aircraft trajectory, it is shown that it is possible to estimate the horizontal position accurately without any changes of ground DME facilities.

• Journal of Advanced Navigation Technology
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• v.18 no.2
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• pp.158-164
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• 2014

For transmitting the ultra-high speed optical signals with better performance, the techniques to suppress or mitigate the signal distortion due to group velocity dispersion and optical Kerr effects are required. Dispersion management (DM), optical phase conjugation, and the combination of these two are promising techniques to compensate for the signal distortion. However, the fixed length of single mode fiber (SMF) and the fixed residual dispersion per span (RDPS) usually used in these optical links restricts flexible link configuration. The goal of this paper is to investigate the possibility of the flexible configurations of the ultra-high and long-haul optical transmission systems by using the artificial and the random distribution of SMF length and RDPS of each fiber spans consisted of the optical link. It is confirmed that the proposed link configurations should be one of the methods suitable for implementing the flexible optical transmission systems, however which depend on other link parameters, such as the averaged RDPS, and the launch power.

• Journal of the Korean Society of Safety
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• v.30 no.3
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• pp.59-66
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• 2015

The undesirable effects of elevated external temperatures at placement on the properties of the fresh and hardened concrete are discussed briefly, and the possible use of the mineral admixtures to mitigate them and the association with water-reducing and retarding admixtures in terms of the mix design which are critical for minimizing slump loss and entrained air loss are examined in this study. To investigate the effects of such the mineral and chemical admixtures on the fresh and hardened properties of concrete exposed to high temperature, a series of concrete mixtures subjected to the high temperature were carried out and then fresh and hardened properties of the mixtures were analyzed and evaluated. Based on the results, new guide lines concerning the appropriate admixtures for hot weather are suggested.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.181-184
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• 2007

Up to now, a lot of houses, roads and other urban facilities have been damaged by natural disasters such as flash floods and landslides. It is reported that the size and frequency of disasters are growing greatly due to global warming. In order to mitigate such disaster, flood forecasting and alerting systems have been developed for the Han river, Geum river, Nak-dong river and Young-san river. These systems, however, do not help small municipal departments cope with the threat of flood. In this study, a real-time urban flood forecasting service (U-FFS) is developed for ubiquitous computing city which includes small river basins. A test bed is deployed at Tan-cheon in Gyeonggido to verify U-FFS. Wireless sensors such as rainfall gauge and water lever gauge are installed to develop hydrologic forecasting model and CCTV camera systems are also incorporated to capture high definition images of river basins. U-FFS is based on the ANFIS (Adaptive Neuro-Fuzzy Inference System) that is data-driven model and is characterized by its accuracy and adaptability. It is found that U-FFS can forecast the water level of outlet of river basin and provide real-time data through internet during heavy rain. It is revealed that U-FFS can predict the water level of 30 minutes and 1 hour later very accurately. Unlike other hydrologic forecasting model, this newly developed U-FFS has advantages such as its applicability and feasibility. Furthermore, it is expected that U-FFS presented in this study can be applied to ubiquitous computing city (U-City) and/or other cities which have suffered from flood damage for a long time.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.4
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• pp.757-770
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• 2020

Industrial Control System(ICS) is a system that measures, monitors, and controls various distributed assets, and is used in industrial facilities such as energy, chemical, transportation, water treatment, and manufacturing plants or critial infrastructure. Because ICS system errors and interruptions can cause serious problem and asset damage, research on prevention and minimization of security threats in industrial control systems has been carried out. Previously wireless communication was applied in limited fields to minimize security risks, but the demand for industrial wireless communication devices is increasing due to ease of maintenance and cost advantages. In this paper, we analyzed the security threats of industrial wireless communication devices supporting WirelessHART and ISA100.11a. Based on the analysis results, we proposed the security requirements for adopting and operating industrial wireless communication devices. We expect that the proposed requirements can mitigate security threats of industrial wireless devices in ICS.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.1
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• pp.45-51
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• 2016

In this paper, we develop an iterative maximum likelihood (ML) receiver for generalized spatial modulation systems. In the proposed ML receiver, to mitigate the deleterious effect of channel information errors on symbol detection, the instantaneous covariance matrix of effective noise is estimated, which is then used to obtain improved ML solutions. The estimated covariance matrix is updated through multiple iterations to enhance the estimation accuracy. The simulation results show that the proposed ML receiver outperforms the conventional ML detection scheme, which does not take the effect of channel information errors into account.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.6
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• pp.1307-1312
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• 2015

As smart-phones become popular, mobile data traffic has been dramatically increasing and intensive researches on the next-generation mobile communication network is in progress to meet the increasing demand for mobile data traffic. In particular, heterogeneous network (HetNet) is attracting much interest because it can significantly enhance the network capacity by increasing the spatial reuse with macro and small cells. In the HetNet, we have several problems such as load imbalance and interference because of the difference in transmit power between macro and small cells and cell range expansion (CRE) can mitigate the problems. In this paper, we propose a new cell selection scheme with adaptive cell range expansion bias (CREB) for ultra dense HetNet and we analyze the performance of the proposed scheme in terms of average cell transmission rate through system-level simulations and compare it with those of other schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.8
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• pp.1699-1704
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• 2009

If detected early enough, cervical cantor may have a good survival rate due to its preneoplastic state. However, the process is so time consuming that a medical expert can handle only a small amount of such examinations. In this paper, we propose a new nucleus extraction algorithm for uterine cervical pap smears in order to mitigate such burdens of medical experts. In the preneoplastic state cytodiagnosis images, it is important to differentiate three main areas - background, cytoplasm and nucleus. Thus, we apply lighting compensation and $3{\times}3$ mask of B channel in order to restore damaged image and remove noises respectively. The cell object is obtained from those clean binarized images with Grossfire algorithm. When there are clusters of cells, the target nucleus can be obtained with repetitive binarization of R channel brightness. In our experiment of using uterine cervical pap smears of 400 magnifications that is common in the diagnostic cytology, our method is able to extract 40 nucleus out of 45 population successfully.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.5
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• pp.805-811
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• 2018

Recently, Format-Preserving-Encryption (FEA) was suggested by the National Security Research institute (NSR) as an encryption method while maintaining the format without a distortion to the intended information to be encrypted. In this paper, we propose a scheme to solve conventional cyber security problems by using FEA scheme. First, we present the method to encrypt signatures and extensions with FEA in order to effectively defend against Ransomeware attacks. This technique can mitigate the exposure to the Ransomeware by encrypting the minimum information. Second, in order to reduce the secret information for Steganography, we introduce a new way to minimize the secret information with FEA. Finally, we compare the operation speed by encryption with FEA and Lightweight Encryption Algorithm (LEA), furthermore when we optimize FEA we want to compare with the performance improvement accompanying with it.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.12
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• pp.1039-1044
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• 2013

We propose a cancellation algorithm based on Alamouti coded OFDM to mitigate ICI due to Frequency Offset (FO) between distributed antennas in the frequency selective fading channel. In the cancellation algorithm, the interference signal is estimated by using the initial detection symbol and then the estimated interference signal is subtracted from the received signal. As the accuracy of initial symbol increases, ICI cancellation becomes more significant. Therefore, the accuracy of the initial detection symbols is very important in the cancellation algorithm. The proposed scheme improves the accuracy of the initial detection symbol by employing an ICI self-cancellation scheme. The proposed cancellation scheme with only one iteration achieves better performance compared to the conventional cancellation schemes with many times iterations based on the conventional Alamouti coded OFDM.