• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4B
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• pp.300-308
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• 2012

Many indoor location tracking technologies have been proposed. Generally indoor location tracking using TOA signal is used, there is a weak point that it's difficult to track the location due to obstacles like a refraction, reflection and dispersion of radio wave. In this paper, we apply ETOA(Estimated-TOA) algorithm in NLOS(Non-Line-Of-Sight) environment to solve above problem. In NLOS environment, TOA value between Beacon and Mobile node is predicted by ETOA algorithm and the tracking of indoor location is also possible to identify using two NLOS beacons of three beacons by this algorithm. We show that the proposed algorithm is accurate location tracking is accomplished using the applying the proposed algorithm to indoor moving robot and the inertia sensor of robot and Kalman filter algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37C no.10
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• pp.1004-1010
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• 2012

In this paper, we propose the algorithm which considers applying recently proposed clock synchronization techniques with quite high accuracy in a few wireless sensor networks researches to time synchronization algorithm for multi-static radar system and especially overcomes the limitation of previous theory, cannot be applied between nodes in non-line of sight (NLOS). Proposed scheme estimates clock skew and clock offset using recursive robust least M-estimator with information of time stamp observations. And we improve the performance of algorithm by tracking and suppressing the time delays difference caused by NLOS system. Futhermore, this paper derive the mean square error (MSE) to present the performance of the proposed estimator and comparative analysis with previous methods.

• Korean Institute of Interior Design Journal
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• v.15 no.1 s.54
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• pp.147-157
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• 2006

The purpose of this study is to fond out the characteristics of color perception and preferred color scheme of the aged who becomes color weak due to yellowed eye sight. For this, this study was composed of two steps. First, an experimental simulation on aged vision using Spectrophotometer(CM-2600d, Minolta) attached Y-2 filter as a quasi lenses of the aged eye. The color data of 120 color chips of the aged vision was measured and analyzed to grasp the characteristics of color perception of the age. Then, a questionnaire survey was carried out with color chips and 8 interior color schemes. They participated in a questionnaire survey of the level of identification among the color chips of 11 tones of R, G, PB, as well as a survey of the preference color schemes. The result of this study are as follow; 1) The range of color perception on hue narrowed into YR, Y, GY, G. Especially, the aged have failed perception of B${\cdot}$PB${\cdot}$P${\cdot}$RP(short wave length of light) by yellowed eye sight. 2) The level of identification among the color chips of 11 tones of R,G,PB are different by each color. But Very Pale, Pale, Strong, Vivid are fractionated similarly in almost color. 3) In the preference of interior color scheme of the aged, preference color harmony scheme Is the complementary color scheme that is easy for identification, rather than analogous color scheme. The preferred dominant color is warm color rather than cool color.

• Korean Journal of Remote Sensing
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• v.20 no.2
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• pp.117-124
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• 2004

A spherical earth surface is used for realistic analysis of the geometrical performance characteristics generated by 2-dimensional line-of-sight (LOS) tilt of the satellite imager using the Time Delay and Integration(TDI) technique. A 2-dimensional LOS tilt ever the spherical Earth surface is proposed to compensate geometric performance degradation caused by the satellite altitude decrease below the normal operation altitude. The compensation can be achieved by TDI re-match without degradation of modulation transfer function and with ground sample distance slightly increased. Effective methods of LOS tilt for the compensation are investigated. This study can be useful for mission assurance and flexibility in imager operation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.508-516
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• 2019

In this paper, we propose a guidance law to control Impact Angle in consideration of look angle limit of the missile with strapdown seeker on the non-maneuvering target. The proposed law is based on sliding mode algorithm and generates acceleration commands using look angle and line of sight information provided by the strapdown seeker and navigation system. And, target velocity and target path angle are provided by like TADS (Target Acquisition and Designation System) at launch time. We can confirm that the target interception and impact angle control are possible through the convergence of the proposed sliding surface. In addition, it is possible to confirm that the sign of derivative result of the look angle at the maximum and minimum look angle is opposite to the sign of the look angle, so the look angle limit is not exceeded.

• The Journal of Korean Institute of Information Technology
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• v.16 no.12
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• pp.93-100
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• 2018

Inverse Synthetic Aperture Radar(ISAR) image is 2-dimensional radar cross section distributions of a target. For target approaching along radar's line of sight(LOS), the bistatic ISAR can compensate for the weakness of the monostatic ISAR which can not obtain the vertical resolution of the image. However, bistatic ISAR have longer processing times and variability in scattering mechanisms than monostatic ISAR, so target identification using only bistatic ISAR images can be inefficient. Therefore, this paper analyzes target identification performance using monostatic and bistatic ISAR images of targets approaching along radar's LOS and proposes a method of target identification through fusion of two radars. Simulation results demonstrate that identification performance through fusion is more efficient than identification performance using only monostatic, bistatic ISAR images.

• Journal of the Korea Computer Graphics Society
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• v.25 no.3
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• pp.65-73
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• 2019

Recently commercial mixed-reality devices have be launched and a variety of mixed-reality content has produced, but narrow field of view, which appear to be hardware technical limitations, are mentioned as an important issue for hindering immersion and limiting the scope of use. We propose a new innovative system that cooperate multiple beam projectors and a number of mixed reality devices. Using this technology, users can maximize immersion and minimize frustration of narrow viewing angles through 3D object rendering on background of large 2D screens. This system, named BtS (Beyond the Sight), is implemented on a client-server basis and includes the ability to calibrate between devices, share spatial coordinate systems, and synchronize real-time renderings as core modules. In this paper, each configuration module is described in detail and the possibility of its performance and application is shown through the introduction of mixed reality content case created using BtS system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.583-584
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• 2022

Due to the development of drones, drone missions are performed in various fields, and BVLOS (Beyond Visual Line Of Sight) flight is performed in a wide area. Most drones operate through radio frequency (RF) communication and can only fly in a limited radius of about 1-2 km. To overcome this, in this paper, we propose a multi-communication protocol-based drone control system to control drones performing missions in BVLOS using RF and LTE (Long Term Evolution). The proposed system consists of a control unit and a drone unit. The control unit transmits one control signal generated from the remote controller through RF and LTE. The drone unit classifies the control signal transmitted through RF and LTE according to the priority of the communication protocol and delivers it to the FC (Flight Controller). Through the proposed control system, it is possible to overcome the RF communication distance limit and prevent the communication disconnection situation.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.1-10
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• 2024

The radio propagation characteristics of the 6, 10, and 17 GHz frequency bands in multiple paths in an indoor lobby environment were analyzed. The line-of-sight (LOS) and non-LOS (NLOS) paths were measured from a distance of 2-16 m (0.5 m intervals) from the transmitting to the receiving antenna positions. For basic transmission losses, three parameters were compared using the floating intercept path loss model corresponding to the path. For a root mean square delay spread, the measurement results were compared for cumulative probabilities of 10, 50, and 90%. Propagation loss and propagation delay occurred in all measured frequencies owing to the existence of pillars and an unusual lobby structure. Thus, a measurement scenario for an indoor lobby environment and the provision of standard measurement data was proposed. The results may facilitate research on the radio propagation characteristics of 5G and millimeter-wave bands in indoor lobby environments with various structures.

• Proceedings of the KOR-KST Conference
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• 1996.02a
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• pp.59-86
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• 1996

Current methods for evaluating unsignalized intersections, and estimating level-of-service (LOS) is determined from efficiency-based criteria such as little or no delay to very long delays. At present, similar procedures to evaluate intersections using safety-based criteria do not exist. The improvement of sight distances at intersections is the most effective way of improving intersection safety. However, a set of procedures is necessary to account for the limitations in current methodology. Such an approach would build upon such methods, but also account for: deficiencies in the current deterministic solution for the determination of intersection sight distances; opportunity for an accident and severity of an accident; and cost-effectiveness of attaining various levels of sight distances. In this research, a model that estimates the degree of safety at two-way stop-controlled intersections is described. Only crossing maneuvers are considered in this study because accidents caused by the crossing maneuvers are the dominate type among intersection accidents. Monte Carlo methods are used to estimate the hazard at an intersection as a function of roadway features and traffic conditions. Driver`s minimum gap acceptance in the crossing vehicles and headway distribution on the major road are used in the crossing vehicles and headway distribution on the major road are used in the model to simulate the real intersectional maneuvers. Other random variables addressed in the model are: traffic speeds; preception-reaction times of both drivers in the crossing vehicles and drivers in oncoming vehicles on the major road; and vehicles on the major roads. The developed model produces the total number of conflicts per year per vehicle and total potential kinetic energy per year per vehicle dissipated during conflicts as measurements of safety at intersections. Based on the results from the developed simulation model, desirable sight distances for various speeds were determined as 350 feet, 450 feet and 550 feet for 40 mph, 50 mph and 60 mph prevailing speed on the major road, respectively. These values are seven to eight percent less than those values recommended by AASHTO. A safety based level-of-service (LOS) is also developed using the results of the simulation model. When the total number of conflicts per vehicle is less than 0.05 at an intersection, the LOS of the intersection is `A' and when the total number of conflicts per vehicle is larger than 0.25 at an intersection, the LOS is `F'. Similarly, when the total hazard per vehicle is less than 350, 000 1b-ft2/sec2, the LOS is `F'. Once evaluation of the current safety at the intersection is complete, a sensitivity analysis can be done by changing one or more input parameters. This will estimate the benefit in terms of time and budget of hazard reduction based upon improving geometric and traffic characteristics at the intersection. This method will also enable traffic engineers in local governments to generate a priority list of intersection improvement projects.