• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.8
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• pp.471-481
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• 2003

The acts of biological immune system are similar to the navigation for autonomous mobile robots under dynamically changing environments. In recent years, many researchers have studied navigation algorithms using artificial immune networks. Conventional artificial immune algorithms consist of an obstacle-avoidance behavior and a goal-reaching behavior. To select a proper action, the navigation algorithm should combine the obstacle-avoidance behavior with the goal-reaching behavior. In this paper, the neural network is employed to combine the behaviors. The neural network is trained with the surrounding information. the outputs of the neural network are proper combinational weights of the behaviors in real-time. Also, a velocity control algorithm is constructed with the artificial immune network. Through a simulation study and experimental results for a autonomous mobile robot, we have shown the validity of the proposed navigation algorithm.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.1
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• pp.1-12
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• 2019

In this paper, we implement a navigation software of a Global Navigation Satellite System (GNSS) receiver based on a commercial purpose GNSS software receiver platform and verify its performance by performing experimental tests for various GNSS signals available in Korea region. The SX3, employed in this paper, is composed of an application program and a Radio Frequency (RF) frontend, and can capture and process multi-constellation and multi-frequency GNSS signals. All the signal processing procedure of SX3 is accessible by the receiver software designer. In particular for an easy research and development, the Application Programing Interface (API) of the SX3 has a flexible architecture to upgrade or change the existing software program, equipped with a real-time monitoring function to monitor all the API executions. Users can easily apply and experiment with the developed algorithms using a form of Dynamic Link Library (DLL) files. Thus, by utilizing this flexible architecture, the cost and effort to develop a GNSS receiver can be greatly reduced.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.2
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• pp.87-94
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• 2019

The Global Navigation Satellite System (GNSS) Real-Time Kinematic (RTK) positioning has been widely used in geodesy, surveying, and navigation fields. RTK can benefit enormously from the integration of multi-GNSS. In this study, we develop a GPS/BeiDou Navigation Satellite System (BDS) RTK integration algorithm for long baselines ranging from 128 km to 335 km in South Korea. The positioning performance with GPS/BDS RTK, GPS-only RTK, and BDS-only RTK is compared in terms of the positioning accuracy. An improvement of positioning accuracy over long baselines can be found with GPS/BDS RTK compared with that of GPS-only RTK and that of BDS-only RTK. The positioning accuracy of GPS/BDS RTK is better than 2 cm in the horizontal direction and better than 5 cm in the vertical direction. A lower Relative Dilution of Precision (RDOP) value with GPS/BDS integration can obtain a better positional precision for long baseline RTK positioning.

• Journal of Positioning, Navigation, and Timing
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• v.13 no.2
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• pp.137-147
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• 2024

This paper presents a novel Long Short-Term Memory (LSTM) network architecture for the integration of an Inertial Measurement Unit (IMU) and Global Navigation Satellite Systems (GNSS). The proposed algorithm consists of two independent LSTM networks and the LSTM networks are trained to predict attitudes and velocities from the sequence of IMU measurements and mechanization solutions. In this paper, three GNSS receivers are used to provide Real Time Kinematic (RTK) GNSS attitude and position information of a vehicle, and the information is used as a target output while training the network. The performance of the proposed method was evaluated with both experimental and simulation data using a lowcost IMU and three RTK-GNSS receivers. The test results showed that the proposed LSTM network could improve positioning accuracy by more than 90% compared to the position solutions obtained using a conventional Kalman filter based IMU/GNSS integration for more than 30 seconds of GNSS outages.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.8
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• pp.133-140
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• 2002

In this paper, the structure of integrated navigation computer for experiment is proposed. It is designed for considering the real time processing and data storage capacity. It will be used in missile, aircraft, submarine system and experimental vehicle. The I/O device supports IMU, GPS, odometer, altimeter, depth sensor, inclinometer etc. And the main storage device uses the tape device. That can improve the system stability. Therefore it can be used in a high dynamic or shock environment. The embedded linux is used as an Operating System. For the real time capability, sensor data processing and algorithm processing units are seperated. The time synchronization is referenced by IMU data.

• Speech Sciences
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• v.6
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• pp.219-233
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• 1999

This paper presents a real-time implementation of a speaker independent speech recognition system based on a discrete hidden markov model(DHMM). This system is developed for a car navigation system to design on-chip VLSI system of speech recognition which is used by fixed point Oak DSP core of DSP GROUP LTD. We analyze recognition procedure with C language to implement fixed point real-time algorithms. Based on the analyses, we improve the algorithms which are possible to operate in real-time, and can verify the recognition result at the same time as speech ends, by processing all recognition routines within a frame. A car noise is the colored noise concentrated heavily on the low frequency segment under 400 Hz. For the noise robust processing, the high pass filtering and the liftering on the distance measure of feature vectors are applied to the recognition system. Recognition experiments on the twelve isolated command words were performed. The recognition rates of the baseline recognizer were 98.68% in a stopping situation and 80.7% in a running situation. Using the noise processing methods, the recognition rates were enhanced to 89.04% in a running situation.

• Journal of Korean Port Research
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• v.13 no.2
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• pp.189-198
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• 1999

The purpose of this paper is to develop a knowledge-based real-time decision support system to support decision makers for efficient berth operation of Inchon Port. In these days the berth operation problems have been many studied. The berth operation rules differ from port to port and the problem is highly dependent on natural geographical and operational environment of port. In Inchon Port the ship’s entrance into port and departure from port is extremely affected status of dock. In this paper we analyzed some effects of dock a specific character of Inchon Port with a real data of ship’s in Inchon Port. And reconstruct a previous expert’s knowledge of berth allocating problem in Inchon Port. Also the mechanism for the efficient berth operation has been studied by repeatedly dispatching in order to obtain a best effect of berth allocation, with real-time updated information for delay at service time of a specific berth and changing of a working-berth. The system is developed with graphic user interface(GUI) concept using user interactive approach. And this system will be provide decision support maker with an efficient and fast way to berth allocating and reduce wastes of time space and manpower in Inchon Port operation.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.652-653
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• 2015

This study investigates the effect of real-time traffic information on the traffic flows in Korea. Recently, the development of smartphones has made it easier to use the route guidance service based on real-time traffic information. By the Big Data analysis in the study, it was found that the number of postings on the web community sites increased sharply in 2010 and 2011 when the smartphones spread widely. In the analysis of the traffic speeds by time, the average traffic speeds for morning and evening rush hours on weekdays from 2009 to 2014 of the 142 sections in the 6 national highways in Gyeonggi-do, Korea were used. From the results of the analysis, it was found that the percentage of the number of sections with the improved traffic flows increased greatly in 2012 compared to 2011. The findings of the study indicate the effect of the real-time traffic information on improving traffic flows.

• Journal of Navigation and Port Research
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• v.30 no.4
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• pp.285-290
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• 2006

Shipping companies consider most of the ship turnaround time as a critical factor when selecting a rolling port for reducing costs. So, many researchers have been studying for the optimization of preplanning and high~performance of the Gantry Cranes (GCs) in container terminals for faster loading and unloading. Therefore, in this paper, we propose an RFID (Radio Frequency Identification) based RTLS (Real-Time Location System) for reducing the ship turnaround time in ubiquitous port environment. In addition, pre-planning based on ubiquitous computing environment will support the GC and Yard Tractors (YTs), and reduce ship turnaround time more effectively. Especially, the proposed method enormously enhances the productivity of loading for the twin-lift system It will reduce the whole lead-time in the process of port logistics.

• Journal of Navigation and Port Research
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• v.29 no.4
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• pp.341-347
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• 2005

A unique technique to extract the phase in time domain is proposed in order to measure the time parameters such as speed and depth by transmitting sound and electric waves. In the signal analysis processing, the phase of pulse signal can be transformed and digitalized with local data in real time without the effect of direct current bias and Nyquist limits. This method is sensitive to base frequency of pulse signal with high spacial resolution and is effective to compare two signals which have different forms. It is expected that the phase analysis technique will be applied to the measurement of the speed and depth accurately by ultrasonic pulse signal in water.