• Journal of Satellite, Information and Communications
• /
• v.7 no.3
• /
• pp.30-34
• /
• 2012

National Meteorological Satellite Center(NMSC) of Korea Meteorological Administration(KMA) has launched to implement the application development to get prepared for the space weather operation since 2010. As a action of KMA's space weather work, NMSC constructed Global Navigation Satellite System(GNSS) application system for meteorology and space weather. We will introduce NMSC's space weather application system which derives regional TEC(Total Electron Content) in near real time using nation-wide GNSS network data. First, We constructed system for collecting GNSS data, which is currently collecting about 80 stations operated by agencies like NGII(National Geographic Information Institute), Central Office of DGPS(Differential GPS), and KASI(Korea Astronomy and Space Science) including KMA's own data of 2 stations. In order to retreive regional TEC over Korean peninsular, we build up the automatic processes running every 1-hour. In these processes, firstly, GNSS data of every stations with 24 hours time window are processed to derive DCBs(Differential Code Biases) of each GNSS station and TEC values on every ionosphere piercing point(IPP). Then we made gridded regional TEC map with resolution of 0.25 degree from 31N, 121E to 41N, 135E by combination of all station results within 30 minutes window with assumption that TEC of a given point during a given 30 minutes window would have a constant value. The grid points without TEC value are interpolated using Barnes objective analysis. We presentour regional TEC maps, which can describe better on the status of ionosphere over Korean peninsular compared to IGS TEC maps.

• Korean Security Journal
• /
• no.22
• /
• pp.145-168
• /
• 2010

Since Alarm Monitoring Service was introduced in Korea in 1981, the market has been increasing and is expected to increase continually. Some factors such as the increase of social security need and the change of safety consciousness, increase of persons who live alone could be affected positively on Alarm Monitoring Service industry. As Alarm Monitoring Service come into wide use, the understanding of electronic security service is spread and consumer's demand is difficult, so consideration about new developmental plan is need to respond to the change actively. Electronic security system is consist of various kinds of element, so every element could do their role equally. Alarm Monitoring Service should satisfy consumer's various needs because it is not necessary commodity, also electronic security device could be easily operated and it's appearance has to have a good design. To solve the false alarm problem, detection sensor's improvement should be considered preferentially and development of new type of sensor that operate dissimilarly to replace former sensor is needed. On the other hand, to settle the matter that occurred by response time, security company could explain the limit on Alarm Monitoring System to consumer honestly and ask for an understanding. If consumer could be joined into security activity by security agent's explanation, better security service would be provided with mutual confidence. To save response time the consideration on the introduction of GIS(Global Information System) is needed rather than GPS(Global Positioning System). Although training program for security agents is important, several benefits for security agents should be considered together. The development of new business model is required for preparation against market stagnation and the development of new commodity to secure consumer for housing service rather than commercial facility service. for the purpose of those, new commodity related to home-network system and video surveillance system could be considered, also new added service with network between security company and consumer for a basis is to be considered.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.10A
• /
• pp.922-929
• /
• 2005

This paper proposes an adaptive pilot beacon equipment for mobile communication systems based on direct spread spectrum technology which generates the pilot channel for handoff between base stations by using the information acquired from the downstream wireless signal regarding the overhead channel information. Such an adaptive pilot beacon equipment will enable low power operation since among the wireless signals, only the pilot channel will be generated and transmitted. The pilot channel in the downstream link of the CDMA receiver is used to acquire time and frequency synchronization and this is used to calibrate the offset for the beacon, which implies that time synchronization using GPS is not required and any location where forward receive signal can be received can be used as the installation site. The downstream link pilot signal searching within the CDMA receiver is performed by FPGA and DSP. The FPGA is used to perform the initial synchronization for the pilot searcher and DSP is used to perform the offset correction between beacon clock and base station clock. The CDMA transmitter the adaptive pilot beacon equipment will use the timing offset information in the pilot channel acquired from the CDMA receiver and generate the downstream link pilot signal synchronized to the base station. The intermediate frequency signal is passed through the FIR filter and subsequently upconverted and amplified before being radiated through the antenna.

• Korean Journal of Construction Engineering and Management
• /
• v.12 no.4
• /
• pp.59-69
• /
• 2011

Construction works have become larger and more complex, improving productivity by introducing Information Technology (IT) is pursued. In this circumstance, many different kinds of project management system is being introduced, and various IT technologies are applied such as Personal Digital Assistant (PDA), Bar Code, Radio Frequency Identification (RFID), Web Camera, and so on. However, these kinds of technologies might cause reprocessing of information and ineffectiveness of project because of lack of real time information processing technology or separation between construction sites and management offices. Therefore, this research aims to develop Application that can be applied efficiently for construction material management, by understanding problems of former management system with questionnaires and extracting functions with analysis of requirements. This will be possible to input information automatically, to process and check material information in real time, and to identify the location of necessary material. Then, the problem of separation between construction sites and management offices are solved, and as a result, more efficient management of materials in construction sites will become possible.

• KIISE Transactions on Computing Practices
• /
• v.21 no.2
• /
• pp.154-159
• /
• 2015

Over the past few years, user needs in the smartphone application market have been shifted from diversity toward intelligence. Here, we propose a novel cognitive agent that plans the daily routines of users using the lifelog data collected by the smart phones of individuals. The proposed method first employs DPGMM (Dirichlet Process Gaussian Mixture Model) to automatically extract the users' POI (Point of Interest) from the lifelog data. After extraction, the POI and other meaningful features such as GPS, the user's activity label extracted from the log data is then used to learn the patterns of the user's daily routine by POMDP (Partially Observable Markov Decision Process). To determine the significant patterns within the user's time dependent patterns, collaboration was made with the SNS application Foursquare to record the locations visited by the user and the activities that the user had performed. The method was evaluated by predicting the daily routine of seven users with 3300 feedback data. Experimental results showed that daily routine scheduling can be established after seven days of lifelogged data and feedback data have been collected, demonstrating the potential of the new method of place-time-activity coupled daily routine planning systems in the intelligence application market.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.34 no.11A
• /
• pp.882-890
• /
• 2009

In this paper, we describe a compensation method that can be used for the situation where Loran receivers lose their phase lock to the received Loran signals when Loran signals are employed for the synchronization of national infrastructures such as telecommunication networks, electric power distribution and so on. In losing the phase lock to the received signals in a Loran receiver, the inner oscillator of the receiver starts free-running and the performance of the timing synchronization signals which are locked to the oscillator's phase is very severly degraded, so the timing accuracy under 1 us for a Primary Reference Clock (PRC) required in the International Telecommunications Union (ITU) G.811 standard can not be satisfied in the situation. Therefore, in this paper, we propose a method which can compensate the phase jump by using a compensation algorithm when a Loran receiver loses its phase lock and the performance evaluation of the proposed algorithm is achieved by the Maximum Time Interval Error (MTIE) of the measured data. From the performance evaluation results, it is observed that the requirement under 1 us for a PRC can be easily achieved by using the proposed algorithm showing about 0.6 us with under 30 minutes mean interval of smoothing with 1 hour period when the loss of phase lock occurs.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.2
• /
• pp.50-62
• /
• 2016

With programmable applications that utilize sensors, such as global positioning systems and accelerometers, smartphones provide an unprecedented opportunity to collect behavioral data in an unobtrusive and cost-effective manner. This paper assesses the relative accuracy and reliability of the Future Mobility Sensing (FMS), a smartphone-based prompted-recall travel survey. We compared the data extracted from FMS with the data collected from the Korea Passenger Trip Survey (PTS), a traditional self-reported, paper-based travel survey. In total, 46 undergraduate students completed the PTS for seven consecutive days, while also carrying their smartphones with the activated FMS applications for the same time span. After completing the PTS, the participants validated their FMS data on the web-based prompted recall surveys. We then matched the validated FMS data with the PTS-based records. The FMS turns out to be superior in detecting short trips, which are usually under-reported in self-reported travel surveys. The reported PTS travel times are longer than for the FMS, suggesting that participants tend to overestimate their travel time in the PTS. This study contributes to the ongoing development of smartphone-based travel behavior data collecting methods.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.22 no.2
• /
• pp.105-116
• /
• 2023

The fatality rate of secondary accidents is seven times that of general traffic accidents. If limited to highways, one in four deaths are said to occur from secondary accidents. Unexpected situations which do not give drivers time to prepare are the cause of secondary accidents. This risk results in more fatalities on highways with high driving speeds. Existing studies have conducted research on traffic accidents and on secondary traffic accidents that occur after a primary traffic accident, without considering unexpected situations that may occur on the road. Therefore, to reduce damage and casualties caused by secondary accidents, there is a need to create a safe road environment by removing the possibility of causing accidents. This study analyzes whether the day of occurrence, time of occurrence, and radius of the curve of an unexpected situation are related to the occurrence of an unexpected situation. This study was based on data of accidents that occurred in 2022 on the Cheonan-Nonsan Expressway and the Seoul-Yangyang Expressway. The radius of the curve was calculated by dividing the section of the highway into straight, clothoid, and curved sections through cluster analysis. Results of the analysis indicate that the day and time of occurrence and the curve radius are associated with unexpected situations.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.7A
• /
• pp.770-777
• /
• 2007

Smaller cell size in the micro-cell or pico-cell structure brings about more frequent hand-overs between cells, and higher speed movement of the mobile terminal makes short the permissible time interval for executing these hand-over procedures. In this situation the hand-over failure may occur or some packets may be lost during the hand-over. Moreover a rapid degradation of throughput is triggered by packet re-transmission for compensating such errors. The QoS (Quality of Services) of mobile multimedia applications with higher bits rate requirements and higher speed mobility are severely affected by even shot service interruption. This paper proposes a new hand-over scheme to provide seamless services in the next generation mobile communication systems. Simulation is done to evaluate the performance of the proposed scheme based on its hand-over failure rate and packet loss rate.

• Spatial Information Research
• /
• v.20 no.4
• /
• pp.83-92
• /
• 2012

Location-based services (LBS) are increasingly popular due to the improvement of geo-positioning capabilities and wireless communication technology. However, in order to enjoy LBS services, a user requesting a query must send his/her exact location to the LBS provider. Therefore, it is a key challenge to preserve user's privacy while providing LBS. To solve this problem, the existing method employs a 2PASS cloaking framework that not only hides the actual user location but also reduces bandwidth consumption. However, 2PASS does not fully guarantee the actual user privacy because it does not take the real user distribution into account. Hence, in this paper, we propose a nearest neighbor query processing algorithm that supports K-anonymity property based on the weighted adjacency graph(WAG). Our algorithm not only preserves the location of a user by guaranteeing k-anonymity in a query region, but also improves a bandwidth usage by reducing unnecessary search for a query result. We demonstrate from experimental results that our algorithm outperforms the existing one in terms of query processing time and bandwidth usage.