• Journal of Korean Society for Atmospheric Environment
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• v.20 no.5
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• pp.697-711
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• 2004

Severe haze, mist, and fog phenomena occurred in the central part of Korea during 15~25 May 2003 resulted in poor visibility and air quality. When these phenomena occurred, Korean peninsula was under the effects of anticyclone. The atmosphere was stable, and wind speed was so weak. Under this meteorological conditions, air quality was worse and worse. The characteristics of aerosol in Seoul, Incheon, and Gosan (Jeju) during this period are investigated from the $PM_{10}$. TSP concentrations and aerosol number concentrations. Concentrations of $PM_{10}$ and TSP measured at KMA increased upto 176 and 230 J.${\mu}g/m^3$ on 22 May 2003, respectively. Aerosol number concentrations of size range from 0.82 to 6.06 ${\mu}m$ increased in Seoul on 17, 19, and 21~24 May 2003, and the concentrations of $NO_2$ and $SO_2$had maximum value of 0.165 ppm at Gwanak Mt. and 0.036 ppm at Guro-dong on 23 May 2003, respectively. Result from analysis on heavy metal elements showed high concentrations of Zn, Pb, Cr, Ni, Cu, and Cd during 20~24 May 2003. This event is examined by comprehensive analyses of synoptic weather conditions, satellite images, concentrations of suspended particles and air pollutants, and heavy metal elements.

• Publications of The Korean Astronomical Society
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• v.32 no.1
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• pp.197-199
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• 2017

Using the InfraRed Camera (IRC) on board the infrared astronomical satellite AKARI we study the ${3.3{\mu}m}$ polycyclic aromatic hydrocarbon (PAH) feature and its connection to active galactic nucleus (AGN) properties for a sample of 54 hard X-ray selected bright AGN, including both Seyfert 1 and Seyfert 2 type objects. The sample is selected from the 9-month Swift/BAT survey in the 14-195 keV band and all of the sources have known neutral hydrogen column densities ($N_H$). The ${3.3{\mu}m}$ PAH luminosity ($L_{3.3{\mu}m}$) is used as a proxy for star-formation (SF) activity and hard X-ray luminosity ($L_{14-195keV}$) as an indicator of the AGN power. We explore for possible difference of SF activity between type 1 (un-absorbed) and type 2 (absorbed) AGN. We use several statistical analyses taking the upper-limits of the PAH lines into account utilizing survival analysis methods. The results of our log($L_{14-195keV}$) versus log($L_{3.3{\mu}m}$) regression shows a positive correlation and the slope for the type 1/unobscured AGN is steeper than that of type 2/obscured AGN at a $3{\sigma}$ level. Also our analysis shows that the circum-nuclear SF is more enhanced in type 2/absorbed AGN than type 1/un-absorbed AGN for low $L_{14-195keV}$ luminosity/low Eddington ratio AGN, while there is no significant dependence of SF activity on the AGN type in the high $L_{14-195keV}$ luminosities/Eddington ratios.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.2 no.1
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• pp.29-37
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• 1999

Land cover classification is an essential basic information in natural environment management; however, land cover classification studies in Korea have not yet been proceeded to a sufficient level. At the present, only a limited number of the precedent studies that only cover definite city area has been conducted. Furthermore, there is almost no research conducted on the land cover classification schemes that could accurately classify the Korea's land cover conditions. This study primarily focuses on the land cover classification scheme which carries the most urgent priority in order to classify and to map out the Korean land cover conditions. In order to develop the most suitable land cover classification scheme, many foreign land cover classification cases and projects that are being carried out were reviewed in depth. The land cover classification scheme this study proposes comprises 3 levels : The first level consists of 7 different classes; the second level consists of 22 different classes; and the third level is made up of 50 classes. The land cover classification map will serve many important roles in natural environment management, such as the conjecture of natural habitats and estimation of oxygen production or carbon dioxide absorption capability of a forest. In water pollution modelling, the land cover classification data can be used to estimate and locate non-point sources of water pollution. If applied to a watershed, modelling it will allow to estimate the total amount of pollution from non-point sources of pollution in the water shed. The land cover classification data will also be good as a barometer data that determines defusion of air pollutants in air pollution modelling.

• Journal of Korea Multimedia Society
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• v.13 no.12
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• pp.1767-1777
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• 2010

In digital TV broadcasting, such as terrestrial, cable, satellite, and IPTV, the head-end of digital TV broadcasting has a more complicated transmission structure than that of analog TV broadcasting. Furthermore, digital TV broadcasting has a feature that supports multiplex models, such as Multiple Program Transport Stream (MPTS). Therefore, the purpose of our work was to design and examine a more efficient new system of emergency alert message transmission to support the digital TV broadcasting environments. Digital TV broadcasting is the IP generation or RF transmission of 8-VSB, QAM, and QPSK modulated through a multiplexer or re-multiplexer multiplexed stream as a MPEG-2 Transport Stream after content encoding. The new system proposed in this paper transmits an emergency alert message without scrambling after replacing the PID and payload of the -packet with the message prototype in the TS stream from the multiplexer. If we need to transmit an emergency alert message under digital TV broadcasting services, then the receiver first checks the PID of each packet in the TS stream for the emergency alert message. Next, if a packet is determined to be an emergency alert message, then the set-top box displays the message on the TV screen using its function of On Screen Display, or the PC based software displays the message on the monitor screen using its function of overlay with user interface if the packet is found to be an emergency alert message. We have designed an emergency alert message protocol and a system model. By experiments and analysis of the system, we concluded that the system achieved efficiency and the ability to send and receive emergency alert messages using the system under different digital TV broadcasting service environments.

• Journal of Advanced Navigation Technology
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• v.19 no.6
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• pp.465-472
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• 2015

In order to improve the performance of TCAS it should improve the performance of the sensor, which transmits a variety of information. In this paper, To improve the performance of the existing radar sensors such as being used in behalf of the next generation air traffic control system, ads-b the applied. In addition, ADS-B in a high precision by using information from the correction GPS system, SBAS assume would be able to apply an improved location accuracy for TCAS and analyzed TCAS and ADS-B. Played the simulation results, TCAS equipment receives the help of these ADS-B can calculate a CPA to determine the position of the aircraft in advance, and it was confirmed that it is possible to reduce the unnecessary RA operation, also, the pilot reduction and the workload, it has advantages such as fuel consumption and time associated with the reduced operation unnecessary RA was confirmed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2014.06a
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• pp.144-145
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• 2014

IoT (Internet of Things) is connected to all things Internet-based people and things, things and objects that communicate information between said intelligent technologies and services. Shipping each of a variety of devices that act independently from each other, but, it is actively interlock with each other is not easy practically days. Ship it within the means of communication, the communication between the ship, the communication between ship and shore configuration, SAN (Ship Area Network), RFID/USN, broadband communications, satellite communications and IT technology to a variety of marine environments for the safe navigation the ship's safety management system for the configuration you want to discuss the plan.

• Korean Journal of Remote Sensing
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• v.29 no.2
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• pp.243-251
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• 2013

The optical properties of long-range transported Asian dust were studied by the satellite observations and Sun/sky radiometer measurements from the Aerosol Robotic Network(AERONET) in Northeast Asia. The movement of Asian dust from source regions to downwind areas was tracked by the Ozone Monitoring Instrument(OMI) derived aerosol product imagery. The optical properties of Asian dust were classified for geographical locations, which are source regions such as deserts area in Dunhuang and Inner Mongolia, downwind areas such as Yulin and Beijing, and long-range transported regions such as Korea(Anmyon and Gosan) and Japan(Noto). In general, relatively higher aerosol mass loadings with larger aerosol particles at desert regions were found. Aerosol Optical Depth(AOD) decreased significantly in downwind areas and long-range transported areas, which was accompanied by increased Angstrom exponents. This indicates the effects of aerosol mixing with various pollutants during transport of Asian dust plume on aerosol optical properties. Moreover, relatively high Single-Scattering Albedo(SSA) at 440 nm values ranging from 0.90 - 0.96 and increasing tendency of SSA with wavelength were observed at source region. The spectral dependence of SSA decreased during long-range transport.

• Journal of the Korean Society of Propulsion Engineers
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• v.19 no.4
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• pp.61-68
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• 2015

Reactive sprays of two propellant combinations(GOx/kerosene and $GN_2O$/ethanol) were observed and compared with each other as a basic research of visualizing supercritical combustion. A shadowgraph imaging method was used to visualize the reactive sprays, and shadowgraph images were converted to density gradient magnitude images to analyse the structure of reactive sprays. The gas-liquid interface of GOx/kerosene spray showed rougher boundary and steeper density gradient near the injector face than the $N_2O$/ethanol at similar combustion chamber pressure. Spray core length was calculated from averaged density gradient magnitude images and it was revealed that spray core length of GOx/kerosene was shorter than that of $GN_2O$/ethanol, although momentum flux ratio of GOx/kerosene propellant combination was lower.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.11
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• pp.82-88
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• 2013

It is important to give lightning warning prior to a cloud-to-ground (CG) discharge within an Area of Concern (AOC) because most of lightning damage and victim are usually occurred by the first lightning in the AOC. The aim of this study is to find the optimal operation conditions of the automated lightning warning systems in order to make the best use of the available data. In this paper, the test-operated results of the automated lightning alert and risk management system (ALARM) based on detections of CG discharge and eletrostatic field and optimized at probability of lightning have been described. It was possible to obtain the following warning performance parameters: probability of detection (POD), false alarm ratio (FAR), probability of lightning (POL) and failure-to-warn rate (FTW). The data obtained from trial operation for 5months were not sufficient but the first analysis of domestic lightning warning was carried out. We have observed that the evaluated statistical results through trial operation depend on the various factors such as analysis methods and criteria, topographical conditions, etc. Also we suggest some methods for improvement of POL and POD including the finding of the optimal electric field threshold level to be used, based on the high values of FAR and FTW found in this work.

• Journal of Positioning, Navigation, and Timing
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• v.6 no.4
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• pp.211-221
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• 2017

Ellipsodially referenced survey (ERS) is considered as one of the challenging issues in the hydrographic surveys due to the fact that the bathymetric data collected by this technique can be readily transformed either to the geodetic or the chart datum by application of some geoscientific models. Global Navigation Satellite Systems (GNSS) is a preferred technique to determine the ellipsoidal height of a vessel reference point (RP) because it provides cost-effective and unprecedentedly accurate positioning solutions. Especially, the GNSS-derived heights include heave and dynamic draft of a vessel, so as for the reduced bathymetric solutions to be potentially free from these corrections. Although over the last few decades, differential GNSS (DGNSS) has been widely adopted in the bathymetric surveys, it only provides limited accuracy of the vertical component. This technical barrier can be effectively overcome by adopting the so-called GNSS carrier phase (CPH) based techniques, enhancing accuracy of the height solution up to few centimeters. From the positioning algorithm standpoint, the CPH-based techniques are categorized under absolute and relative positioning in post-processing mode; the former is precise point positioning (PPP) correcting errors by the global or regional models, the latter is post-processed kinematic positioning (PPK) that uses the differencing technique to common error sources between two receivers. This study has focused on assessment of achievable accuracy of the ellipsoidal heights obtained from these CPH-based techniques with a view to their applications to hydrographic surveys where project area is, especially, few tens to hundreds kilometers away from the shore. Some field trials have been designed and performed so as to collect GNSS observables on static and kinematic mode. In this paper, details of these tests and processed results are presented and discussed.