• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.115-122
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• 2015

Global Positioning System (GPS) is used in various fields such as communications systems, transportation systems, e-commerce, power plant systems, and up to various military weapons systems recently. However, GPS receiver is vulnerable to jamming signals as the GPS signals come from the satellites located at approximately 20,000 km above the earth. For this reason, various anti-jamming techniques have been developed for military application systems especially and it is also required for commercial application systems nowadays. In this paper, we proposed a dual-channel Global Navigation Satellite System (GNSS) RF ASIC for digital pre-correlation anti-jam technique. It not only covers all GNSS frequency bands, but is integrated low-gain/attenuation mode in low-noise amplifier (LNA) without influencing in/out matching and 14-bit analogdigital converter (ADC) to have a high dynamic range. With the aid of digital processing, jamming to signal ratio is improved to 77 dB from 42 dB with proposed receiver. RF ASIC for anti-jam is fabricated on a 0.18-μm complementary metal-oxide semiconductor (CMOS) technology and consumes 1.16 W with 2.1 V (low-dropout; LDO) power supply. And the performance is evaluated by a kind of test hardware using the designed RF ASIC.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1995.04a
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• pp.534-544
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• 1995

Many electronic products employ menu-driven interfaces for user-system dialogue. Unlike the software user interfaces, a small single-line display, such as a Liquid Crystal Display, is typically used to present menu items. Since the display can show only a single menu item at a time, more serious navigation problems are expected with single-line display menus(SDM). This study attempts to provide a set of unique guidelines for the design of the SDM based on empirical results. A human factors experiment was conducted to examine the effects of four design variables: menu structure, user experience, navigation aid, and number of targets. The usability of design alternatives was measured quantitatively in four different aspects, which were speed, accuracy, inefficiency of navigation, and subjective user preference. The analysis of variance was used to test the statistical effects of the design variables and their interaction effects. A set of design guidelines was drawn from the results which can be applied to the design of human-system interfaces of a wide variety of electronic consumer products using such displays. Since more generalized guidelines could be provided by constructing prediction models based on the empirical data, some powerful performance models are also required for the SDM. As a preliminary study, a survey was done on the performance models for ordinary computer menus.

• Journal of the Korean Professional Engineers Association
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• v.41 no.5
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• pp.55-58
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• 2008

GPS is the global Navigation Satellite System which is developed by the United States Department of Defense as an abbreviation of the Global Positioning System. The GPS uses a constellation of 24 Medium Earth Orbit satellites that transmit precise microwave signals, that enable GPS receivers to determine their location, speed, direction, and time. Following, the shooting down of Korean Air Lines Flight 007 in 1983. President Ronald Reagan issued a directive making the system available free for civilian use as a common good. Since then, GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, scientific uses, and hobbies such as geocaching. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1383-1384
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• 2015

In this paper, a dynamics model embedded navigation filter is newly suggested for underwater autonomous systems without position or attitude aid. In order to ensure the observability on the INS errors, the hydrodynamics of the underwater vehicle is incorporated with the INS attitude error. This approach allows us to estimate and compensate the INS errors in spite of using external velocity sensor. Through the simulation, the performance and effectiveness of the proposed scheme are demonstrated.

• Journal of Advanced Navigation Technology
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• v.2 no.1
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• pp.11-21
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• 1998

There have been active research efforts in the development of a dual-use millimeter-wave radiometer as an aircraft landing aid in low visibility conditions. In this paper, we constructed a radiometer operating at the Ka-band where it is relatively easy to build RF components. The radiometer is used to collect radiometric signatures of some vehicles and land surfaces. Measured signatures suggest that vehicles with metallic surfaces yield signatures markedly different from nearby land surfaces so that they can easily be detected by a simple radiometer.

• Journal of Navigation and Port Research
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• v.43 no.2
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• pp.86-92
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• 2019

IMO has enacted a convention that air pollution due to emissions of ships and sulfur oxides emissions should be significantly reduced by 2020. Based on the current support policies, this work intended to draw up the government support plans required by the shipping companies. Analytic Hierarchy Process analysis was done with factors derived from brainstorming and literature studies. The analysis results showed that the cost factor was generally the most important criterion and the Financial Aid was relatively more important within this cost factor. The policy implications for the regulation of sulfur oxides emissions was provided.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2022.11a
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• pp.149-150
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• 2022

External forces acting on the mooring facilities include wave, wind, current, and ship's kinetic energy. In particular, the ship's kinetic energy is changing as the ship become larger, and larger carrying capacity. It was intended to analyze the berthing velocity measurement data at on tanker terminals equipped with a DAS (Docking Aid System) through statistical means and algorithms and use it as basic data for safer and more efficient pier design and pilotage.

• Archives of design research
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• v.15 no.3
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• pp.167-180
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• 2002

This study investigates effective ways to help users form a correct mental model of the hierarchical information space (HIS) in small display. The focus is the effect of color cue on understanding the structure and navigating the information space. The concept of color space (CS) corresponds well to the HIS - one color has a unique position in the CS as a piece of information does in HIS. In this study, we empirically examined two types of color cue, namely, categorical and depth cue. Hue was used as a categorical cue and tone was used as a depth cue. In our experiment, we evaluate the effectiveness of the color cues in the mobile internet system. Subjects were asked to perform four searching tasks and four comparison tasks. The results of experiment reveal that the categorical cues significantly improve the user's mental model whereas decrease navigation performances. The depth cues cannot aid in understanding the HIS as well as improve navigation performances. This study concludes with limitations of the study and descriptions of future studies.

• Journal of the Korean Institute of Navigation
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• v.22 no.3
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• pp.9-16
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• 1998

Loran C is a low frequently , pulsed. hyperbolic radio aid to navigation system, which operates in the 90 to 110 kHz frequency band. The position accuracy is not excellent but the repeatable and relative accuracy is very good, and it is very useful for fishing vessel in coastal waters. The operation of China north sea chain9GRI 7430) was begun on January, 1996, and in order to evaluate the accuracy of this chain, it was observed with Loran C receiver (LC-90, Furuno) in July 9 and December 30, 1997 at the fixed position of Kunsan national university. The obtained results were as follows : The time difference error of M-X, M-Y pair were $0.5{\mu}s$, $4.4{ \mu}s$ respectively and the mean time difference of M-X, M-Y pair were $15120.4{,\mu}s$ $32085.4{\mu}s$ respectively. The Loran C signals were received steadily and the daily fluctuation of time difference was very small. The longitudinal position error was very much than latitudinal position error, and the mean position error was about 1091.8m.

• Journal of Navigation and Port Research
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• v.39 no.4
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• pp.307-312
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• 2015

ARPA(Automatic Radar Plotting Aid) is a device to calculate CPA(closest point of approach)/TCPA(time of CPA), true course and speed of targets by vector operation of relative courses and speeds. The purpose of this study is to develop target acquisition and tracking technology for ARPA Radar implementation. After examining the previous studies, applicable algorithms and technologies were developed to be combined and basic ARPA functions were developed as a result. As for main research contents, the sequential image processing technology such as combination of grayscale conversion, gaussian smoothing, binary image conversion and labeling was deviced to achieve a proper target acquisition, and the NNS(Nearest Neighbor Search) algorithm was appllied to identify which target came from the previous image and finally Kalman Filter was used to calculate true course and speed of targets as an analysis of target behavior. Also all technologies stated above were implemented as a SW program and installed onboard, and verified the basic ARPA functions to be operable in practical use through onboard test.