• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.10a
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• pp.3-10
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• 2006

Recently it is coming to be hish reality on visual system in ship-handling simulator depending on the technical development of 3D computer graphics. Even with high reality, it is possible that visual information presented seafarers through screen or display is not equivalent to the real world. In docking maneuvering, visual targets or obstructs are sighted close to ship's operator or within few hundred meters, so it might be possible to affect visual information such as the difference between both eyes' and single eye's visual sight. Because it is not possible to perceive of very slow ship's movement by visual in case of very large vessels, so the Doppler Docking SONAR and/or Docking Speed and Distance Measurement Equipment were developed and applied for safety docking maneuvering. By the way, the simulator training includes the ship's maneuvering training in docking, but in Ship-handling Simulator and also onboard, there are some limitations of perception of ship's movement with visual information. In this paper, perception of ship's movement with visual system in Ship-handling Simulator and competition of performances of visual systems that are conventional screen type with Fixed Eye-point system and Mission Simulator. We got some conclusions not only on the effectiveness for visual system but also on the human behavior in docking maneuver.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2243-2250
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• 2014

In wireless sensor networks(WSNs), geographical routing algorithms can enhance the network capacity. However, in real WSNs, it is difficult for each node to know its physical location accurately. Especially, indoor environments contain various obstacles such as concrete wall, furniture which cause non-line-of-sight(NLOS) conditions. To solve the problem, we propose location error compensation algorithm by using two difference topology constructions. First topology is based on mobile node's location which is obtained from anchor nodes. Second topology is based on mutual distance from neighbor nodes. The proposed algorithm efficiently detects and corrects the location errors and significantly enhances the network performance of geographic routing in the presence of location errors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.8B
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• pp.1593-1600
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• 1999

This paper describes the acquisition modeling of an airborne target for target tracking simulation of infrared homing missiles. The modeling, of which key technologies are the sub-modeling for target infrared signature, atmospheric transmission, and receiver characteristics, shows the acquisition process of an airborne target under various tracking conditions determined by line-of-sight, distance, and atmospheric conditions. We confirm the validity of the modeling by applying it to simulations concerned with target tracking. The modeling gives a guideline to determine an optimum detector and a defection band for effective discrimination of the target among false targets.

• Journal of Communications and Networks
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• v.13 no.5
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• pp.494-498
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• 2011

Satellite digital multimedia broadcasting (S-DMB) systems use gap fillers (GFs) to provide wireless multimedia services to non-line-of-sight locations. GFs act as repeaters, and S-DMB systems require GF networks in order to guarantee mobile reception. Each GF covers a cell or sector. In order to provide contiguous coverage of an area comprising two or more cells or sectors, multiple GFs are needed. However, when multiple GFs are situated close to each other, interference is likely to occur. As a result, in this study, we have investigated system-level environments for planning the design of interference-free GF networks in S-DMB systems. Our investigations revealed that S-DMB services are unavailable because of quality deterioration caused by interference when the delay attributable to a GF and the satellite signals exceeds ${\pm}$256 chips and the distance between the GF and its reception terminal is greater than 4.6 km. On the basis of this analysis, we conducted a field test that confirmed that the above-mentioned time delay can be controlled in such a way as to ensure high quality S-DMB services.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.186-193
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• 2020

We investigate a fog-detection CCT control system using low deck lighting as a solution to the forward visibility of pole-type street lamps employed on existing roads. The lighting standards were met with a light source that has less compared with those of pole-type street lamps. The results show that the transmission rate was increased by changing the color temperature by automatically recognizing fog in bad weather and minimizing the phenomenon of lighting. In addition, it was allowed to create a safer and more comfortable driving environment for drivers owing to flicker or light pollution of existing pole-type street lamps. As a result, if lighting is used at a lower level than pole-type street lamps, the accident rate caused by securing the driver's forward visibility can be reduced sharply and existing problems can be resolved.

• International Journal of Highway Engineering
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• v.15 no.6
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• pp.103-111
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• 2013

PURPOSES : Previous Speed Profile reflects the patterns of speeds in sections of tangents to curves in the roads. However these patterns are uniform of speeds and Acceleration/Deceleration. In oder to supplement these shortcomings. this study made a new profile which can contain factors of Acceleration/Deceleration through theories of Previous Speed Profiles. METHODS : For sakes, this study developed the speed prediction model of Rural Multi-Lane Highways and calculated Acceleration/Deceleration by appling a Polynomial model based on developed speed prediction model. Polynomial model is based on second by second. Acceleration/Deceleration Profile is developed with the various scenarios of road geometric conditions. RESULTS : The longer an ahead tangent length is, The higher an acceleration rate in curve occurs due to wide sight distance. However when there are big speed gaps between two curves, the longer tangent length alleviate acceleration rate. CONCLUSIONS : Acceleration/Deceleration Profile can overview th patterns of speeds and Accelerations/Decelerations in the various road geometric conditions. Also this result will help road designer have a proper guidance to exam a potential geometric conditions where may occur the acceleration/deceleration states.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.67-74
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• 1999

Where an interchange is located just after a tunnel not only it is impossible to install the traffic signs in tunnel sections but also sufficient sight distance to identify the interchange can't be provided. The objective of this study is to suggest the safety based spacing between tunnel and interchange. For this study accident rate was used as an index representing characteristics for vehicle operation to suggest the appropriate spacing. Traffic volume and the number of accidents on freeway from 1992 to 1997 were analyzed. The relationship between accident rate and spacing represents negative logarithm function such that shorter spacing increases accident rate. An appropriate safety based spacing between tunnel and interchange for four lane freeway with the design speed of 100kph was found as 2.6km.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.1
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• pp.183-188
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• 2008

Satellite DMB(Digital Multimedia Broadcasting) uses the Cap Filler(GF) that provides a service to the wave shade area of the satellite signal that is a non-line of sight area. The GF is the repeater and the Satellite DMB Systems certainly must construct the GF Network toguarantee the movement reception of the terminal. As the coverage of the GF is formed the Cell or Sector, when the multiple GF is established to be contiguous, the problem of the interference will be able to occur. This paper describes the Satellite DMB system and the GF, and it investigate the design fundamentals plan of the GF Network that it will be able to reduce this problem. As a result, in case of the distance that GF and terminal unit is above 4.6Km, service is not provided because of quality degradation according to mutual interference.

• Journal of the Optical Society of Korea
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• v.15 no.1
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• pp.96-102
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• 2011

Simultaneous measurements using a scanning spectrograph system and transmissometer were performed for the first time over an urban site in Gwangju, Korea, to derive the ambient $NO_2$ volume mixing ratio. The differential slant column densities retrieved from the scanning spectrograph system were converted to volume mixing ratios using the light traveling distance along the scanning line of sight derived from the transmissometer light extinction coefficients. To assess the performance of this system, we compared the derived $NO_2$ volume mixing ratios with those measured by an in situ chemiluminescence monitor under various atmospheric conditions. For a cloudless atmosphere, the linear correlation coefficient (R) between the two data sets (i.e., data derived from the scanning spectrograph and from the in situ monitor) was 0.81; the value for a cloudy atmosphere was 0.69. The two sets of $NO_2$ volume mixing ratios were also compared for various wind speeds. We also consider the measurement errors, as estimated from an error propagation analysis.

• ETRI Journal
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• v.43 no.3
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• pp.377-388
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• 2021

Owing to the difficulties associated with conducting millimeter-wave (mmWave) field measurements, especially in high-speed train (HST) environments, most propagation channels for mmWave HST have been studied using methods based on simulation rather than measurement. In this study, considering a linear cell layout in which base stations are installed along a railway, measurements were performed at 28 GHz with a speed up to 170 km/h in two prevalent HST scenarios: viaduct and tunnel scenarios. By observing the channel impulse responses, we could identify single- and double-bounced multipath components (MPCs) caused by railway static structures such as overhead line equipment. These MPCs affect the delay spread and Doppler characteristics significantly. Moreover, we observed distinct path loss behaviors for the two scenarios, although both are considered line-of-sight (LoS) scenarios. In the tunnel scenario, the path loss exponent (PLE) is 1.3 owing to the waveguide effect, which indicates that the path loss is almost constant with respect to distance. However, the LoS PLE in the viaduct scenario is 2.46, which is slightly higher than the free-space loss.