• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.9
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• pp.689-699
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• 2013

During extreme ionospheric storms, anomalous ionospheric delays and gradients could cause potential integrity threats to users of GNSS (Global Navigation Satellite System) augmentation systems. GNSS augmentation ground facilities must monitor these ionospheric anomalies defined by a threat model and alarm the users of safely-of-life applications within time-to-alerts. Because the ionospheric anomaly threat model is developed using data collected from GNSS reference stations, the use of poor-quality data can degrade the performance of the threat model. As the total number of stations increases, the number of station with poor GNSS data quality also increases. This paper analyzes the quality of data collected from Korean GPS reference stations using comprehensive GNSS data quality check algorithms. The results show that the range of good and poor qualities varies noticeably for each quality parameter. Especially erroneous ionospheric delay and gradients estimates are produced due to poor quality data. The results obtained in this study should be a basis for determining GPS data quality criteria in the development of ionospheric threat models.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.23 no.3
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• pp.283-292
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• 2005

After USA removed the Selective Availability (SA), Global Positioning System (GPS) has monopolized the world market and other countries have been depended on GPS, absolutely. So the other countries, Russia, European Community (EC) and Japan, which apprehend to monopolize in technical and strategic parts, are developing the next generation GNSS including GLONASS Galileo and JRANS. And the countries are planning to provide the another GNSS. This research has focused on the next generation GNSS system based on GPS and Galileo system with developing a GNSS simulation software, named as GlMS2005, which generates and analyzes satellite constellation and measurements. Based on the software, a variety of simulation tests have been carried out to recognize limits of GPS-only system and potential benefits of integrated GPS/Galileo positioning in terms of satellite geometry strength and solution accuracy.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.2
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• pp.69-79
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• 2017

In this study, we developed real-time urban stream discharge forecasting model using short-term rainfall forecasts data simulated by a regional climate model (RCM). The National Centers for Environmental Prediction (NCEP) Climate Forecasting System (CFS) data was used as a boundary condition for the RCM, namely the Global/Regional Integrated Model System(GRIMs)-Regional Model Program (RMP). In addition, we make ensemble (ESB) forecast with different lead time from 1-day to 3-day and its accuracy was validated through temporal correlation coefficient (TCC). The simulated rainfall is compared to observed data, which are automatic weather stations (AWS) data and Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA 3B43; 3 hourly rainfall with $0.25^{\circ}{\times}0.25^{\circ}$ resolution) data over midland of Korea in July 26-29, 2011. Moreover, we evaluated urban rainfall-runoff relationship using Storm Water Management Model (SWMM). Several statistical measures (e.g., percent error of peak, precent error of volume, and time of peak) are used to validate the rainfall-runoff model's performance. The correlation coefficient (CC) and the Nash-Sutcliffe efficiency (NSE) are evaluated. The result shows that the high correlation was lead time (LT) 33-hour, LT 27-hour, and ESB forecasts, and the NSE shows positive values in LT 33-hour, and ESB forecasts. Through this study, it can be expected to utilizing the real-time urban flood alert using short-term weather forecast.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.1-8
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• 2017

Knowledge network is considered to be an important factor in securing regional economic performance and competitiveness. In addition, research institutes that are capable of absorbing knowledge tend to form a global knowledge network regardless of geographical factors, and those that are not, are heavily influenced by regional factors. In this study, we examined how much influence of geographical factors of knowledge network is influenced by lower knowledge absorptive capacity in Korea. As a result, it was shown that the higher institutes of knowledge absorption, the more international collaborative research is being carried out. In other words, a region where science and technology has developed means that regional factors are no longer important factors. The results of this study correspond with the discussion of the preceding theories. In addition, it is worthy of study in that the precedent study was carried out in the case study in Korea.

• Journal of Korean Neurosurgical Society
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• v.55 no.1
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• pp.18-25
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• 2014

Objective : This study explored the relationships among demographic (DVs) and clinical variables (CVs), neurocognitive (NOs) and functional outcome (FO) that could be used as prognostic factors for old aged patients with traumatic brain injury (TBI) undergoing or appointed disability evaluation (DE) after treatment. Methods : A total of 162 subjects with TBI above the age of 55 years undergoing DE or appointed to do so after treatments were selected. The patients were divided into two subgroups according to age : a junior elderly group 55 to 64 years old and a senior elderly group over the age of 65. NOs and FO were evaluated using the Seoul Neuropsychological Screening Battery and Clinical Dementia Rating scale. Results : Gender, age, and education level were shown to significantly impact the recovery of NOs after TBI. Other DVs and CVs such as area of residency, occupation, type of injury, or loss of consciousness were not found to significantly affect the recovery of NOs after TBI. Analysis of the relationships among DVs, CVs and NOs demonstrated that gender, age, and education level contributed to the variance of NOs. In FO, loss of consciousness (LOC) was included to prognostic factor. Conclusion : Gender, age and education level significantly influence the NOs of elderly patients with TBI. LOC may also serve as a meaningful prognostic factor in FO. Unlike younger adult patients with TBI, old aged patients with TBI did not show global faking-bad or malingering attitudes to DE for compensation, but assume that they could faking their performance in a test set available visual feedback.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.3
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• pp.677-682
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• 2016

Recently, because Global Positioning System (GPS) achieves accuracy for engagement of enemy targets, GPS guided weapons have a wide range of applications from land through sea to air. Especially, when GPS guided weapon is then launched, it reads current position and searches a course to the target. As we all know, because GPS signals are weak, these signals can be affected by interference. If jamming signal is strong enough, it can jam the receiver of GPS guided weapon. Therefore, anti-jamming technique is an important thing under these conditions. In this paper, the controlling azimuth angle was used to improve navigation performance of precision guided missile under jamming conditions. First of all, precision missiles by GPS positioning such as SLAM-ER and JDAM were investigated. Also, the azimuth cutoff angle of satellites for usable navigation under jamming signals was analyzed by experimental tests. As a result, we found that azimuth cutoff angle under 140 degree can help ensure continuous GPS reception under the missile guidance.

• Journal of Microbiology and Biotechnology
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• v.19 no.7
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• pp.635-646
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• 2009

Rapid and accurate diagnosis of diseases is very important for appropriate treatment of patients. Recent advances in molecular-level interaction and detection technologies are upgrading the clinical diagnostics by providing new ways of diagnosis, with higher speed and accuracy. In particular, DNA microarrays can be efficiently used in clinical diagnostics which span from discovery of diseaserelevant genes to diagnosis using its biomarkers. Diagnostic DNA microarrays have been used for genotyping and determination of disease-relevant genes or agents causing diseases, mutation analysis, screening of single nucleotide polymorphisms (SNPs), detection of chromosome abnormalities, and global determination of posttranslational modification. The performance of DNA-microarray-based diagnosis is continuously improving by the integration of other tools. Thus, DNA microarrays will play a central role in clinical diagnostics and will become a gold standard method for disease diagnosis. In this paper, various applications of DNA microarrays in disease diagnosis are reviewed. Special effort was made to cover the information disclosed in the patents so that recent trends and missing applications can be revealed.

• Journal of Korea Multimedia Society
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• v.10 no.7
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• pp.902-911
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• 2007

GSM platform is a hugely successful wireless technology and an unprecedented story of global achievement. In less than ten years since the first GSM network was commercially launched, it became the world's leading and fastest growing mobile standard, using over 1 billion GSM subscribers across more than 200 countries of the world. GSM platform evolved into 3th generation mobile communication which includes not only voice call services but also the international roaming and various kinds of the multimedia services. GSM is an essential element techniques a safe data transmission and a personal private protection while support services. However, a crypto algorithm and a secure protocol for a safe data communication using GSM are indicating various kinds of problems. In this paper, we propose a more safer and more efficient authentication protocol in 3th generation network through analysis of GSM security mechanism of 2th/2.5th generation. This security protocol offers enforced security efficiency by using user verification between SIM/ME and reduction of authentication and key agreement step between SIM/ME/AuC.

• The Korean Journal of Applied Statistics
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• v.21 no.5
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• pp.717-726
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• 2008

The purpose of this paper is to assess the financial strength of general insurers by using A.M. Best's rating technique focusing on quantitative standards. A quantitative evaluation of fifteen larger general insurers' financial strength and operating performance relative to the Best's top group is carried out. The quantitative evaluation is done in 5 key areas; growth, efficiency, profitability, safety and liquidity. The results show that there is a big gap between domestic large insurers and American insures in all areas except stable growth of operations. Therefore, domestic insurers have to strive to strengthen financial soundness through profitability and should increase the capacity to retain more commercial business and reinsurance in order to become global players.

• Journal of the Society of Naval Architects of Korea
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• v.50 no.6
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• pp.421-428
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• 2013

This study aims at numerically investigating the angle of attack characteristics of the rudder behind a rotating propeller. The rotating propeller of 5 blades and the full spade rudder are placed in the numerical water tunnel with a uniform flow condition to consider propeller-rudder interaction. The turbulence closure model is employed to simulate the three-dimensional unsteady incompressible viscous turbulent flow around the propeller and the rudder. The present numerical method are well verified by comparing with the experimental results. In order to identify the dependence of the angle of attack of the rudder on the rudder angle, a wide range of rudder angles is considered. The present study carried out the quantitative and qualitative analysis of the angle of attack in terms of the pressure distribution, streamlines and the evaluation of the flow incidence, resulting in that the angle of attack increases as we move from the root and the tip to the center of the rudder, regardless of the rudder angle. The distribution of the angle-of-attack along the span is strongly affected by rotating propeller flow and rudder angle. Consequently, the distribution of the angle-of-attack of the oncoming flow against the rudder leading edge plays a role in determination of rudder performance.