• Journal of Institute of Control, Robotics and Systems
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• v.14 no.8
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• pp.727-732
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• 2008

In this paper, the state-space representation of generalized complimentary filter is proposed. Complementary filter has the suitable structure to merge information from sensors whose frequency regions are complementary. First, the basic concept and structure of complementary filter is introduced. And then the structure of the generalized filter and its state-space representation are proposed. The state-space representation of complementary filter is able to design the complementary filter by applying modern filtering techniques like Kalman filter and $H_{\infty}$ filter. To show the usability of the proposed state-space representation, the design of Inertial Navigation System(INS) vertical channel damping loop using Global Positioning System(GPS) is described. The proposed GPS/INS damping loop lends the structure of Baro/INS(Barometer/INS) vertical channel damping loop that is an application of complementary filter. GPS altitude error has the non-stationary statistics although GPS offers navigation information which is insensitive to time and place. Therefore, $H_{\infty}$ filtering technique is selected for adding robustness to the loop. First, the state-space representation of GPS/INS damping loop is acquired. And next the weighted $H_{\infty}$ norm proposed in order to suitably consider characteristics of sensor errors is used for getting filter gains. Simulation results show that the proposed filter provides better performance than the conventional vertical channel loop design schemes even when error statistics are unknown.

• Journal of the Korean Institute of Navigation
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• v.20 no.1
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• pp.1-10
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• 1996

The assesment of the safety of ship's transit in a curved narrow channel consists of the maneuvering safety determined by the chance of running aground, the maneuvering difficulty determined by ship's workload, and shiphandler's subjective evaluation. In this study, to examine the correlation between shiphandler's subjective evaluation and the maneuvering safety, the real-time and full-mission shiphandling simulator in the Korea Marine Training & Research Institute(KMTRI) was utilized. On the conning bridge of the shiphandling simulator, 50 experienced masters have conducted the modeled vessel of 60, 000 deadweight tonnage along the designed channel under 3 different environmental conditions. It was possible to assess and analyze theoretically the correlation between the shiphandler's subjective evaluation and maneuvering difficulty under each environmental condition by quantifying the data obtained from the tests. The results are as follows: $\circled1$ As the degree of maneuvering difficulty increases, the shiphandler's subjective evaluation increases in the designed channel under the designed environmental condition. $\circled2$ In the straight area, not the bend of the designed channel, maneuvering difficulty increases sharply under the environmental condition of current and wind coming from the stern.

• Journal of Navigation and Port Research
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• v.36 no.8
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• pp.631-635
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• 2012

Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In this paper, in order to design an efficient packet structure, we employ channel coding scheme and phase recovery algorithm. For channel coding scheme, half rate LDPC channel coding scheme with N=1944 and K=972 was used. Also, decision directed phase recovery was used for correcting phase offset induced by multipath. Based on these algorithms, we propose length of data for optimal packet structure in the environment of oceanic experimentation.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.544-550
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• 2009

In this paper, we proposed the radio wave propagation characteristics of the next-generation ultrafast wireless communication system in millimeter-wave fading channel. For considering doppler shift and Rayleigh fading simultaneously, the fading simulator of Jakes model implemented and analyzed the performance of the next-generation wireless communication system. In addition, the error rate characteristics of DS-CDMA system analyzed in the millimeter-wave fading channel and the system performance improved by coding technique and diversity technique.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.74-77
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• 2014

This paper suggested an error control for multi-channel running on machine to machine environment. This system is suitable for recovering software fault for multimedia CSCW(Computer Supported Cooperative Works) based on machine to machine environment. It is necessary for the system to be protected by reactivity of media service instance instead of breaking process of session. This paper explains a performance analysis of an error recovery system of M2M based computing collaboration environment using rule-based DEVS modeling and simulation techniques.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.1
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• pp.1-9
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• 1996

A numerical model for predicting depositional processes of navigation channels caused by waves and currents is proposed. In the model, non-equilibrium concentrations of suspended sediment are numerically solved by using the split-operator approach. The calculated concentrations across a channel show good agreements with the measured concentrations in experiments. Based on the calculated concentrations, differences of upward and downward sediment fluxes are estimated to predict topographic changes. The Predicted topographic change across the channel coincides fairly well with the measured profile provided that the currents are relatively stronger than waves.

• Journal of the Korean Institute of Navigation
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• v.8 no.1
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• pp.49-70
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• 1984

Spatial and temporal variations of hydrography and currents are investigated in the Southeastern Sea of Korea during October 1982. The distribution of the water mass of high salinity (>34.40${\textperthousand}$) and low dissolved oxygen concentration (<5.0ml/l) indicates that the Tsushima current flows northward as it passes the Western Channel of the Korea Strait. The cold water (<$6.0^{\circ}c$) with low salinity (<$34.20{\textperthousand}$) and high dissolved oxygen concentration (>6.0ml/l) reaches the bottom of the western channel of the Korea Strait after flowing southward leaning against the slope rather than following the deepest part of the Channel. Repeated sections in the Korea Strait show a remarkable change of hydrographic structure over a period of 4 days ; both warn and cold waters are intensified, particularly in the eastern part of the strait toward the Tsushima Island.

• Journal of Korean Port Research
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• v.7 no.2
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• pp.61-68
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• 1993

Studies on the ship's automatic navigation & berthing control have been continued by way of solving the ship's mathematical model, but the results of such studies have not reached to our satisfactory level due to its non-linear characteristics at low speed. In this paper, the authors propose a new control system which can evaluate as closely as captain's decision-making by using the FNN(Fuzzy Neural Network) controller which can simulate captain's knowledge. This controller contains the concept of safety according to channel width. The learning data are drawn from ship Handling simulator(NavSim NMS-90 MK III) and represent the ship motion characteristics internally. According to learning procedure, the FNN controller can tune membership functions and identify fuzzy control rules automatically. The verified results show that the FNN controller is effective to incorporate captain's knowledge and experience of manoeuvrability in channel.

• Journal of Fashion Business
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• v.4 no.4
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• pp.123-133
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• 2000

The purpose of this study was to examine the usage of internet advertisement, to define the convenient dimensions of information navigation medium, and to examine the difference of convenient information navigation among advertisement types and information design methods. Thirty-four subjects were selected for the survey study and descriptive anlysis, factor analysis and ANOVA were used for the data analysis. The results of this study were: 1. the most perceived channel about the web site information was the search engine, the most preferred type of information design was the mixed type with text and image, and the most preferred medium for fashion information is the magazine. 2. the convenient dimensions of information navigation medium were information understanding, design composition, easy navigation, timely navigation, and convenient navigation. 3. the information design method is the significant factor influencing on the convenient information navigation.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.693-699
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• 2005

To design ship channels is one of important factors for planning and developing a port. Bends in channels should be avoided if possible, but the channel should be widened, if channel bend is unavoidable, considering the swept path of a ship for safe passage. In this study, Variable Bumper Area(VBA) model is applied to determine the channel widths in bends. The result of this study shows that the width of the bend may be designed as nearly same size of that in straight channel in case that the angle of deflection is less than 30 degrees, and that of the bend with 60 degrees deflection should be widened based on the length of the largest ship using the channel and the angle of deflection.