• The Journal of Korean Association of Computer Education
• /
• v.15 no.5
• /
• pp.55-62
• /
• 2012

With the development of mobile communications and Internet technology, there is a strong need to provide seamless and fast connectivity for roaming devices. Generally, the mobile host (MH) may have several available networks when entering a new wireless area. However, the standard of decision for user's internet connection is provided only the subsystem identification (SSID) and signal strength of access point (AP). These two standards could not enough to decide optimal AP to the MH. Therefore, to decide the optimal AP, more information is needed. In this paper, we present additional information such as status of MH, capacity, current load, and depth of network hierarchy, by router advertisement message at layer 3. Also, we proposed decision engine (DE) on the MH that analyzes APs and decides the optimal AP automatically by AP's status information. For the MH, wireless connection period is increased, the power consumption is decreased, and the signaling overhead is reduced. For AP and router, the load balancing is provided and the network topology can also be more efficient.

• The Bulletin of The Korean Astronomical Society
• /
• v.43 no.1
• /
• pp.42.1-42.1
• /
• 2018

Deep Ecliptic Patrol of the Southern Sky (DEEP-South) observation is being made during the off-season for exoplanet survey, using Korea Microlensing Telescope Network (KMTNet). An optimal combination of its prime focus optics and the 0.3 billion pixel CCD provides a four square degrees field of view with 0.4 arcsec/pixel plate scale which is also best suited for small body studies. Normal operation of KMTNet started in October 2015, and a significant portion of the allocated telescope time for DEEP-South is dedicated to targeted observation, Opposition Census (OC), of near-Earth asteroids for physical and taxonomic characterization. This is effectively achieved through multiband, time series photometry using Johnson-Cousins BVRI filters. Uninterrupted monitoring of the southern sky with KMTNet is optimized for spin characterization of a broad spectrum of asteroids ranging from the near-Earth space to the main-belt, including binaries, asteroids with satellites, slow/fast- and non-principal axis-rotators, and thus is expected to facilitate the debiasing of previously reported lightcurve observations. Our software subsystem consists of an automated observation scheduler, a pipelined data processing system for differential photometry, and an easy-to-use lightcurve analysis toolkit. Lightcurves, spin periods and provisional determination of class of asteroids to which the lightcurve belongs will be presented, using the dataset from first year operation of KMTNet. Our new taxonomic classification scheme for asteroids will also be summarized.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2013.05a
• /
• pp.65-67
• /
• 2013

The recent high-performance network equipment is required, and also require high network bandwidth utilization. It is a trend to develop increasingly using multi-core processors for high-performance network servers. Propose a method to improve the performance of the network sub-system, considering the characteristics of multi-core as a way to improve these high-performance and high network throughput. In this paper, we confirm through experiments on how to improve the communication performance, optimize performance and take full advantage of multi-core by Network communication process to improve the performance of the multi-core processor architecture, the process of concentration, the overhead for each core, based on network traffic according to the interrupt affinity in this process to determine the optimal core to give. The experiments were implemented in the Linux kernel, and experiments to improve the network throughput up to 30%, bringing reduces the Linux communication process to improve the performance of the processor overhead of up to 10%.

• Journal of Astronomy and Space Sciences
• /
• v.33 no.3
• /
• pp.221-227
• /
• 2016

As described in the previous paper (Park et al. 2013), the detector subsystem of optical wide-field patrol (OWL) provides many observational data points of a single artificial satellite or space debris in the form of small streaks, using a chopper system and a time tagger. The position and the corresponding time data are matched assuming that the length of a streak on the CCD frame is proportional to the time duration of the exposure during which the chopper blades do not obscure the CCD window. In the previous study, however, the length was measured using the diagonal of the rectangle of the image area containing the streak; the results were quite ambiguous and inaccurate, allowing possible matching error of positions and time data. Furthermore, because only one (position, time) data point is created from one streak, the efficiency of the observation decreases. To define the length of a streak correctly, it is important to locate the endpoints of a streak. In this paper, a method using a differential convolution mask pattern is tested. This method can be used to obtain the positions where the pixel values are changed sharply. These endpoints can be regarded as directly detected positional data, and the number of data points is doubled by this result.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.9
• /
• pp.795-801
• /
• 2014

STEP Cube Lab. classified as a pico-satellite has been being developed by SSTL(Space Technology Synthesis Laboratory) in Chosun University. Its main mission objective is to perform the on-orbit verification of core space technologies, which will be the potential candidates for future space missions. In this paper, to guarantee successful mission operation of the cube satellite under extremely severe space thermal environment condition, the system level thermal design and analysis has been performed. The effectiveness of the design has been verified through on-orbit thermal analysis of cube satellite.

• Journal of KIISE:Computing Practices and Letters
• /
• v.7 no.5
• /
• pp.392-401
• /
• 2001

Nowadays, the amount of image data increase explosively. To manage the large amount of image data efficiently, high-dimensional index structures are necessary. However, as my knowledge none of existing DBMSs supports high-dimensional index structures as access methods of DBMSs. In this paper, we design and implement CIR-Tree as a access method for retrieving image data effectively on the MiDAS-III that is the storage subsystem of the BADA-III. The implemented CIR-Tree manager shows much better retrieval performance than sequential search in performance evaluation.

• Journal of KIISE:Computing Practices and Letters
• /
• v.7 no.5
• /
• pp.522-538
• /
• 2001

This paper presents a cal center which is a subsystem of a web-based real time monitoring system of intensive care units. Based on Computer-Telephony Integration (CTI) technology, the call center attempts to efficiently and automatically send messages to patients\` families, doctors, and other staffs in hospital via communication media suitable to the occasion. The problem of determining appropriate media can be very complicated by the urgency of a message, calling time, and communication media available to the target person. We use the Dempster-Shafer theory, one of the uncertainty handling methods, to determine the most suitable communication media that will transmit a message rapidly and safely. In addition, we use agent technology to perform the calling process without requiring the intervention of the user of the call center. this call center enables message transfer through various communication media in an integrated environment, and relieves medical staff from the calling process, which in turn will make a contribution toward enhancing medical service.

• Journal of Digital Contents Society
• /
• v.10 no.1
• /
• pp.1-10
• /
• 2009

One important issue to generalize the ubiquitous paradigm is the development of user-centralized and intelligent ubiquitous computing systems. Sharing knowledge and correct communication between users and devices are needed to be aware of continuous changed context information and infer services for which users are suited. The goal of this paper is to describe and manage effectively the meaning of services or data which each device offers for interaction between users and devices based on semantic relationships and reasoning. In this paper, we represent semantic data using OWL and design a ubiquitous based intelligent system. We propose some index structures and strategies to process queries classified by each subsystem and adopt labeling schemes to identify classes and resources in the semantic data. We can find devices which satisfies various user's requests exactly and quickly using the proposed strategies.

• Journal of the Korea Society for Simulation
• /
• v.15 no.4
• /
• pp.143-151
• /
• 2006

This paper deals with the simulation model for design and operations of A-Mart logistic center for low temperature products. In developed simulation model, receiving docks, digital classification system (DCS), shipping docks, material handling devices and manual sorting stations are considered. Five types of cargo such as fruits, palletized fruits, delicatessen and fisheries, vegetables and refrigerated cargoes are considered. The simulation model and process animation are developed using the simulation package ARENA. Among various design and operation alternatives consisting of the number of workers of receiving dock, allocation of receiving docks by cargo types, DCS capacity, the number of folk-lift, the number of manual sorting operators and overall layout, the best alternatives of each subsystem are selected by simulation analysis. The major performance measures such as DCS throughput, utilization of operators at each station, receiving docks utilization and folk-lift utilization are considered for the alternative evaluation.

• Journal of Satellite, Information and Communications
• /
• v.5 no.2
• /
• pp.19-24
• /
• 2010

The COMS (Communication Ocean Meteorological Satellite) is a hybrid geostationary satellite including communication, ocean, and meteorological payloads. The COMS includes the MODCS (Meteorological and Ocean Data Communication Subsystem) which provides transmitting the raw data collected by meteorological payload called MI (Meteorological Imager) and ocean payload named GOCI (Geostationary Ocean Color Imager) to the ground station, and relaying the meteorological data processed on the ground to the end-user stations. Here, for the L-band transmit antenna transmitting SD (Sensor Data) signal and the processed signal, from the system point of view, it is required to estimate the combined antenna gain when the L-band transmit is placed with MI and GOCI payloads on the earth panel of COMS. First of all, the L-band transmit horn is designed and analyzed for the requirements given, and then after placing it on the earth panel, the combined gain analysis is performed using three different analysis methods. It's shown that the obtained gain patterns are very similar among three different analysis methods. Finally the antenna gain degradation of less than 0.5 dB is estimated.