• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.10
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• pp.2223-2229
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• 2010

The integrity monitoring of anomalous GPS signal have been researched because of the degradation of GPS satellite performance. It is known that anomalous GPS signal can occur by failure of GPS satellite, sudden increase of ionosphere delay error, SA, wrong modeling for navigation parameters from control segment, and an electromagnetic wave interference, etc. In case of GPS anomaly by satellites can arise from carrier frequency, code and navigation message. In this paper, the scenarios with navigation message errors were made by using GPS simulator, and the influences of GPS navigation message error to receiver were analysed. The anomalies of preamble, bits related TOW count message, subframe ID in HOW, bits related satellite healthy, and the other navigation message errors were described and simulated. Also, the number of satellites, DOP and pseudorange are analyzed to know how the anomalous signal can affect on GPS receiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4B
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• pp.199-206
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• 2008

In this paper, we propose a novel Route_Reconf message as the RSVP message to maintain an RSVP session for hard handoff and consider path-comparing route (PCR) a PCR algorithm to find an intermediate node in the charge of downlink re-establishment. And, we consider information form each mode for the PCR algorithm, which also reduces the frequency and amount of exchanged RSVP message to minimize packet loss and delay between an intermediate node and a receiver. According to the proposed algorithm, a new support node (NSN) and an existing support node (ESN) along the RSVP path can be found; the former is a supporting RSVP session node newly searched and the latter is the last supporting node holding the previous session after handoff. On receiving the Route_Reconf message at the ESN, a new allocated route from a NSN to the MN waiting for the handoff via a new AR is configured by the ESN.

• The KIPS Transactions:PartB
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• v.15B no.2
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• pp.87-94
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• 2008

In this paper, we propose a new vision-based fire detection method for a real-life application. Most previous vision-based methods using color information and temporal variation of pixel produce frequent false alarms because they used a lot of heuristic features. Furthermore there is also computation delay for accurate fire detection. To overcome these problems, we first detected candidated fire regions by using background modeling and color model of fire. Then we made probabilistic models of fire by using a fact that fire pixel values of consecutive frames are changed constantly and applied them to a Bayesian Network. In this paper we used two level Bayesian network, which contains the intermediate nodes and uses four skewnesses for evidence at each node. Skewness of R normalized with intensity and skewnesses of three high frequency components obtained through wavelet transform. The proposed system has been successfully applied to many fire detection tasks in real world environment and distinguishes fire from moving objects having fire color.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.6
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• pp.93-100
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• 2016

This study conducted a quantitative assessment on the environmental flows associated with climate change in the Gosam Reservoir, Korea. The application of RCP 8.5 climate change scenario has found that the peak value of High Flow Pulses has increased by 36.0 % on average compared to historical data (2001 ~ 2010), which is likely to cause disadvantage on flood control and management but the increase in peak value is expected to make a positive impact on resolving the issue of green algal blooms, promoting vegetation in surrounding areas and encouraging spawning and providing habitats for native species by releasing a larger amount of landslides as well as organic matters than the past. However, the decreasing pattern of the peak value of High Flow Pulses is quite apparent with the trend of delay on the occurrence time of peak value, necessitating a long-term impact analysis. The peak value of Large Floods shows a clear sign of decrease against climate change scenario, which is expected to lead to changes in fish species caused by degraded quality of water and decreasing habitats. A quicker occurrence of Small Floods is also expected to make an impact on the growth cycle of aquatic plants, and the reduction in occurrence frequency of Extreme Low Flows is to contribute to increasing the population of and raising the survival rate of native fish, greatly improving the aquatic ecosystem. The results of this study are expected to be useful to establish the water environment and ecological system in adapting or responding to climate change.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.3
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• pp.88-97
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• 2013

This paper presents a robust air-to-fuel ratio (AFR) control algorithm for managing exhaust gas recirculation (EGR) systems. In order to handle production tolerance, deterioration and parameter-varying characteristics of the EGR system, quantitative feedback theory (QFT) is applied for designing the robust AFR control algorithm. A plant model of EGR system is approximated by the first order transfer function plus time-delay (FOPTD) model. EGR valve position and AFR of exhaust gas are used as input/output variables of the plant model. Through engine experiments, parameter uncertainty of the plant model is identified in a fixed engine operating point. Requirement specifications of robust stability and reference tracking performance are defined and these are fulfilled by the following steps: during loop shaping process, a PID controller is designed by using a nominal loop transmission function represented on Nichols chart. Then, the frequency response of closed-loop transfer function is used for designing a prefilter. It is validated that the proposed QFT-based AFR control algorithm successfully satisfy the requirements through experiments of various engine operating points.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.1
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• pp.97-103
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• 2006

In this paper, a control method of a mini ozone generator is proposed, and also a cooling technique is described which is cooling down the flowing air gap into a silent discharger to $2^{\circ}C$ to generate ozone of high density and diffusing power. As the digital control system for this method, a double feedback loop is designed which detects the voltage and current of equivalent capacitor of the discharger and compensates for the poor power waveform caused by the noise at high discharging frequency. During the plant modeling of this system, computing time factor is considered as a unique parameter of the power system to improve the transient responses with regard to fluctuating load and to replenish the computing time delay of the controller. Through the experiment, sinusoidal input current for discharger can be acquired and all the effectiveness of this accurate control system over unstable ozone discharger are proved.

• Journal of Korea Multimedia Society
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• v.8 no.10
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• pp.1403-1410
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• 2005

The synchronization problem is directly related to the quality of service in multimedia communication and especially in real-time communication. In this study, we found the cause of clock fluctuation between encoder and decoder in MPEG-2 system layer was that the standard decoder design only considered a fixed time delay component. To solve it, we proposed Extended-SRTS algorithm, which uses STC as service clock by synchronizing transport stream. As the result, we can improve the effect of frequency-drift, time-varying-network-jitter and packing-jitter and so on And by virtue of this algorithm, we can make low the dependency of network clock, which makes easy to synchronize and connect transparently at the ends point, we expect the proposed algorithm can be widely applied to the field of real -time multimedia communications.

• Journal of Korea Multimedia Society
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• v.13 no.7
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• pp.943-949
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• 2010

This paper presents some improvements on VLSI implementation of lifting-based 9/7 wavelet transform by optimization hardware multiplication. The proposed solution requires less logic area and power consumption without performance loss compared to previous wavelet filter structure based on lifting scheme. This paper proposes a better approach to the hardware implementation using Lefevre algorithm based on extensions of Pattern search methods. To compare the proposed structure to the previous solutions on full multiplier blocks, we implemented them using Verilog HDL. For a hardware implementation of the two solutions, the logical synthesis on 0.18 um standard cells technology show that area, maximum delay and power consumption of the proposed architecture can be reduced up to 51%, 43% and 30%, respectively, compared to previous solutions for a 200 MHz target clock frequency. Our evaluation show that when design VLSI chip of lifting-based 9/7 wavelet filter, our solution is better suited for standard-cell application-specific integrated circuits than prior works on complete multiplier blocks.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2232-2240
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• 2017

IMO has made AIS and VHF mandatory for international sailing vessels through SOLAS, and korea if mandating specific vessels through the law for safety of vessels and the ship installation technology standards. However, due to various communication equipments and complicated usage method, malfunction occurs, and the response delay to the actual structure signal often causes human accidents. So recently, as a part of GMDSS modernization, maritime communication devices are attempting to interwork and integrate different types of marine communication system in order to construct a next generation maritime communication system. In this paper, we describe a technique to implement the DSC function by interlocking and integrating the AIS device and VHF. We will present the basis for achieving domestic technical standards and standardization through the linking algorithm of the data that can extract the ship information from AIS and utilize it the DSC function of VHF.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.5 s.311
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• pp.62-71
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• 2006

Development of an artificial reverberation algorithm with low memory requirements has been an issue of importance in applications such as mobile multimedia devices. One possible solution to this problem is to embed a time-varying all-pass filter to the feedback loop of the comb filter. In this paper, theoretical and perceptual analyses of reverberators embedding time-varying all-pass filters are presented. The analyses are to iud a perceptually acceptable degree of phase variation by the all-pass filter. Based on the analyses, we propose a new methodology of designing reverberators embedding time-varying all-pass filters. Through the subjective tests, we showed that, even with smaller memory, the proposed method is capable of providing perceptually comparable sound quality to the conventional methods involving time-invariant parameters.