• Journal of Advanced Navigation Technology
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• v.27 no.5
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• pp.510-518
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• 2023

This paper introduces a MATLAB graphical user interface (GUI) based software for performance analysis of navigation message and wide area differential correction of regional navigation satellite system (RNSS). This software was developed to analyze satellite orbit/clock-related performance of navigation message and wide area differential correction simulating RNSS for regions near Korea based on different distributions of monitor and reference stations. As a result of software operation, navigation message and wide area differential correction are given as output in MATLAB file format. From the analysis of output, it was confirmed that valid navigation message and wide area differential correction could be generated from the results about statistical feature of orbit and clock prediction errors, cm-level fitting errors for navigation message parameters, and 81.9% enhancement in range error for wide area differential correction.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.10
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• pp.34-39
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• 2010

We developed a path algorithm for ultrafast/wide area laser processing. Demands for high precision laser processing with a wide area has been increasing for a number of applications such as in solar cell battery, display parts, electronic component and automobile industry. Expansion of the area in which laser processing is an important factor to handle the ultrafast/wide area processing, it will require a processing path. Processing path is path of 2- axis stage and stage of change in velocity can be smooth as possible. In this paper, we proposed a smoothingnurbs method of improved speed profile. This method creates soft path from edge part, it is main purpose that scan area ($50mm{\times}50mm$) inside processing path makes path of topology of possible straight line. We developed a simulation tool using Visual C++.

• Journal of Advanced Navigation Technology
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• v.1 no.1
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• pp.3-10
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• 1997

The importance of GPS was great1y increased for aviation after the completion of the GPS satellite constellation in December of 1993. The Wide Area Augmentation System (WAAS) is being developed for operational use in the United States and also a similar system, European Geostationary Navigation Overlay Service (EGNOS), is also under development in Europe. There are needs to develop Wide Area Differential GPS (WADGPS) covering Korea to complete the GNSS mentioned above. The GNSS then allows international aviation users to fly world-wide with a single avionic system. In case of DGPS, it can cover within 100km and needs many stations for serving the widely-spreaded users. But WADGPS can cover wide area via fewer stations than DGPS. In this paper we propose an Korea version of WADGPS and discuss on algorithms and performances.

• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.279-286
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• 2017

In this paper, an optimal approach for the wide-area regulation of control devices in a transmission network is proposed. In order to realize an improved voltage profile and reduced power loss, existing devices such as tap-changing transformers, synchronous machines, and capacitor banks should be controlled in a coordinated and on-line manner. It is well-understood that phasor measurement units in transmission substations allow the system operators to access the on-line loading and operation status of the network. Accordingly, this study proposes efficient software applications that can be employed in area operation centers. Thus, the implanted control devices can be regulated in an on-line and wide-area coordinated approach. In this process, efficient objective functions are devised for both voltage profile improvement and power loss reduction. Subsequently, sensitivity analysis is carried out to determine the best weighting factors for these objectives. Extensive numerical studies are conducted on an IEEE 14-bus test system and a real-world system named the Azarbayjan Regional Transmission Network. The obtained results are discussed in detail to highlight the promising improvements.

• Journal of the Optical Society of Korea
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• v.18 no.5
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• pp.517-522
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• 2014

In this paper we propose an axially distributed image-sensing method with a wide-angle lens to capture the wide-area scene of 3D objects. A lot of parallax information can be collected by translating the wide-angle camera along the optical axis. The recorded wide-area elemental images are calibrated using compensation of radial distortion. With these images we generate volumetric slice images using a computational reconstruction algorithm based on ray back-projection. To show the feasibility of the proposed method, we performed optical experiments for visualization of a partially occluded 3D object.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.316-319
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• 1998

RPWM(Random Pulse Width Modulation) is a switching technique to spread the voltage and current harmonics on the wide frequency area. Using randomly changed switching frequency of the inverter, the power spectrum of the electromagnetic acoustic noise cab be spread to the wide-band area. The wide-band noise is much more comfortable and less annoying than the narrow-band one. So RPWM have been attracting an interest as an excellent method for the reduction of acoustic noise on the inverter drive system. In this paper a new RPPWM (Random Position PWM) is proposed and implemented. Each of three pulses is located randomly in each switching interval. Along with the randomization of PWM pulses, the space vector modulation is executed in the C167 microcontroller also. The experimental results show that the voltage and current harmonics were spread to wide band area and that the audible switching noise was reduced by proposed RPPWM method.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1-9
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• 2008

A wide metropolitan railway and a metropolitan railway in metropolitan area are transportation systems to cope with possible large demand and are under construction continually. A wide metropolitan railway and a metropolitan railway in metropolitan area are running with low speed because it is difficult to improve train speed according to short distances between stations and topography. There is a few study on improving commercial speed on the existing wide metropolitan railway and metropolitan railway in metropolitan area, but there is no study on a new wide metropolitan railway. This study present speed-up scheme of the Sosa-Wonsi line by enlarging the curve radius, reducing the horizontal steep gradient, reducing the stopping time, speeding up at underground section, and installing the PSD, etc. This scheme is evaluated using the simulation technique.

• Journal of Periodontal and Implant Science
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• v.32 no.3
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• pp.577-588
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• 2002

Osseointegrated implants have been established as the standard treatment modality for full/partial edentulous patients since the 1960's, and the long term results for full edentulous patients have proven to be successful. Based on these results osseointegrated implants are now widely used for partial edentulous patients. There has been an increased interest towards the efficacy of wide implants, despite many reports mentioning the lower success rate of wide implants compared to regular implants. Recently, mandibular molar area defects are commonly restored using 2 wide implants, but it is not determined whether which treatment modality-3 regular implants or 2 wide implants-shows superior success rate. In this study, 2 wide implants and 3 regular implants used for the restoration of mandibular molar area are used to compare the survival rate of 1-4 years, and to analyze and compare the failure factors. The following conclusions could be drawn from this study. 1. Wide implants and regular implants showed 94.5% and 97,6% of survival rate respectively. After prosthodontic work, the survival rate was 100% and 98.1% for wide implants and regular implants respectively. 2. 5 failed implants have been removed. 2 wide implants and 1 regular implant have been removed due to failure of osseointegration. 1 wide implant was removed due to abscess formation caused by over-heating, and 1 regular implant was removed due to mechanical failure caused by over-loading within the first year of function. 3. No statistically significant difference was observed with respect to the amount of marginal bone loss of wide and regular implants.(P>0.05) In conclusion, restoration of the mandibular molar area using 3 regular implants was found to be a good treatment modality, and 2 wide implants could he considered a good treatment modality when success factors are taken into account.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.1
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• pp.21-28
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• 2016

The Wide Area Differential Global Positioning System (WADGPS) that uses a number of Global Navigation Satellite System (GNSS) reference stations are implemented with various types and provide services as it can service a wide range of areas relatively. This paper discusses a constellation design of reference stations and performance analysis of the WADGPS. It presented performance results of static and dynamic users when wide area correction algorithm was applied using eight reference stations.

• Journal of the Society of Disaster Information
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• v.19 no.3
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• pp.729-736
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• 2023

Purpose: The purpose of the Activation of Public Transportation by Analysis of Factors Influencing Satisfaction of Commuting Hours in the Metropolitan Area. Method: This study analyzed the factors affecting wide-area commuting time and satisfaction for office workers who perform wide-area commuting. Result: in the case of commuting satisfaction for wide-area commuting hours by region, commuting time satisfaction was relatively low in the metropolitan area as the average commuting time was high, and commuting time satisfaction was relatively high in the non-metropolitan area as the average commuting time was low. Conclusion: In the future, the government will establish or improve express railways and wide-area buses to reduce wide-area commuting time, and build urban highways to shorten passenger car use time, which will reduce commuting time, but qualitative indicators are more important. In other words, even if commuting time is long, life satisfaction increases, so quality of life is important, and it is necessary to improve commuting time satisfaction rather than simple indicators of commuting time, so both qualitative and quantitative aspects of commuting time need to be improved.