• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5264-5281
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• 2017

Multihop relay-based cellular networks are attracting much interest because of their throughput enhancement, coverage extension, and low infrastructure cost. In these networks, relay stations (RSs) between a base station (BS) and mobile stations (MSs) drastically increase the overall spectral efficiency, with improved channel quality for MSs located at the cell edge or in shadow areas, and enhanced throughput of MSs in hot spots. These relay-based networks require an advanced radio resource management scheme because the optimal amount of radio resource for a BS-to-RS link should be allocated according to the MS channel quality and distribution, considering the interference among RSs and neighbor BSs. In this paper, we propose optimal resource planning algorithms that maximize the overall utility of relay-based networks under a proportional fair scheduling policy. In the first phase, we determine an optimal scheduling policy for distributing BS-to-RS link resources to RSs. In the second phase, we determine the optimal amount of the BS-to-RS link resources using the results of the first phase. The proposed algorithms efficiently calculate the optimal amount of resource without exhaustive searches, and their accuracy is verified by comparison with simulation results, in which the algorithms show a perfect match with simulations.

• Journal of the Korean Home Economics Association
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• v.39 no.12
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• pp.51-63
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• 2001

With the development of information technology, more and more internet sites are available to consumers. Increasing on the interests of diet and health in modem society, there are numerous internet sites dealing with food, nutrition and health. Considering the importance and expected roles of internet sites in information dissemination in the future world, it is important to put more efforts to encourage internet sites with more accurate an useful information. Up to present, not much work has been done on quality analysis and evaluation of the internet information. This study aimed to develop a model to evaluate and rank the internet information according to its quality so that consumers can be guided toward correct information source. Three models were adapted from the literature for pilot study to develop a model suitable for evaluation of contents of sites related to food and nutrition information. From the pilot study, a evaluation model was developed with criteria more relevant to Korean internet site by expert panel. Evaluation criteria of the model is authority, accuracy, objectivity, coverage, and user-friendliness. For the objective and systematic evaluation, scores were assigned totaling maximum 100 point to each evaluation criteria factors. The model developed in this study could be used as one for other internet sites in area other than food and nutrition.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.10 no.1
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• pp.243-268
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• 1999

The purpose of this study is to develop the classification scheme in subject-based directory search engine for educational research information on the web. Five classification systems. Yahoo Korea, Argus Clearinghouse, DDC, ERIC thesaurus and KEDI thesaurus were measured in terms of coverage of subject fields, system logic, accuracy of terminology and efficiency of searching. For the design of Classification Scheme, this study considered the content of subject areas, features of information resources and efficiency based on users. Finally, the Classification Scheme was established in terms of 16 main divisions and 47 sub-divisions in educational research information.

• Korean Journal of Geomatics
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• v.4 no.2
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• pp.39-45
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• 2004

Building reconstruction attempts to generate geometric and radiometric models of existing buildings usually from sensory data, which have been traditionally aerial or satellite images, more recently airborne LIDAR data, or the combination of these data. Extensive studies on building reconstruction from these data have developed some competitive algorithms with reasonable performance and some degree of automation. Nevertheless, the level of details and completeness of the reconstructed building models often cannot reach the high standards that is now or will be required by various applications in future. Hence, the use of terrestrial sensory data that can provide higher resolution and more complete coverage has been intensively emphasized. We developed a fusion framework for building reconstruction from terrestrial sensory data, that is, points from a laser scanner, images from digital camera, and absolute coordinates from a total station. The proposed approach was then applied to reconstructing a building model from real data sets acquired from a large complex existing building. Based on the experimental results, we assured that the proposed approach cam achieve high resolution and accuracy in building reconstruction. The proposed approach can effectively contribute in developing an operational system producing large urban models for 3D GIS with reasonable resources.

• Journal of the Korean Society for Library and Information Science
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• v.38 no.2
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• pp.161-187
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• 2004

This study concerns DB quality of the Web databases which has been produced in medical science. For the quality evaluation of Embase and PubMed, 10 evaluating criteria were developed on the basis of literature review. The evaluation result showed that PubMed has superiority to the currentness, accuracy, completness, consistency, ease of use, customer support, searchability, cost, and network ＆ H/W on DB, but Embase has only superiority to the coverage. It is needed for purchasing, user training, and library service based on the above evaluation result.

• Journal of the Korean Institute of Navigation
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• v.3 no.1
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• pp.47-77
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• 1979

A microwave Navigational Aid system is suggested suitable for fishing boats too small to be equipped with Radar or Radio-Direction-Finder. The system proposed here is similar to that of Talking-Beacon developed in Japan, but the distinctive modification proposed is that an increase of sixteen times in peak transmitting power, thus an accompanying increase of coverage, is achieved with the same mean transmitting power as that of Japan without sacrificing the clearness of azimuth information, by adopting a pulse repetition modulation instead of pulse width modulation as in Japan system. An experimental land station transmitter of transmitting frequency of 9, 370MHz and of peak power of 35kw with a microwave beam of 1 degree in horizontal width and 7 degrees in vertical width rotating once every three minutes, and also an experimental receiver of 20-dB in sensitivity and of an assumed cost of 100 dollars, operated by a 12 volts battery source are made, and the sail test results are reported showing that a bearing infromation of an accuracy of within two degrees can be obtainable every three minutes at a distance of as far as 24 miles from the transmitter if the transmitter is located as high as 100 meters above sea-level.

• Korean Journal of Remote Sensing
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• v.24 no.1
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• pp.65-78
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• 2008

This study compares the relative accuracy and consistency of four split-window land surface temperature (LST) algorithms (Becker and Li, Kerr et ai., Price, Ulivieri et al.) using 24 sets of Terra (Aqua)/Moderate Resolution Imaging Spectroradiometer (MODIS) data, observed ground grass temperature and air temperature over South Korea. The effective spectral emissivities of two thermal infrared bands have been retrieved by vegetation coverage method using the normalized difference vegetation index. The intercomparison results among the four LST algorithms show that the three algorithms (Becker-Li, Price, and Ulivieri et al.) show very similar performances. The LST estimated by the Becker and Li's algorithm is the highest, whereas that by the Kerr et al.'s algorithm is the lowest without regard to the geographic locations and seasons. The performance of four LST algorithms is significantly better during cold season (night) than warm season (day). And the LST derived from Terra/MODIS is closer to the observed LST than that of Aqua/MODIS. In general, the performances of Becker-Li and Ulivieri et al algorithms are systematically better than the others without regard to the day/night, seasons, and satellites. And the root mean square error and bias of Ulivieri et al. algorithm are consistently less than that of Becker-Li for the four seasons.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.1
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• pp.74.2-74.2
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• 2019

Mass measurement of high-redshift galaxy clusters with high accuracy is important in constraining cosmological parameters. Extremely massive clusters at high redshift may impose a serious tension with the current ΛCDM paradigm. SPT-CL J2040-4451 at z=1.48 is considered one such case given its redshift and mass estimate inferred from the SZ data. The system has also been confirmed to be indeed massive from a recent weak-lensing (WL) analysis. Comparison of the WL mass with the spectroscopic result may provide invaluable information on the dynamical stage of the system. However, the existing spectroscopic coverage of the cluster is extremely poor; only 6 blue star-forming galaxies have been found within the virial radius, which results in highly inflated and biased velocity dispersion. In this work, we present a spectroscopic analysis of the member candidates using Gemini Multi-Object Spectrographs (GMOS) observation in Gemini South. The observation was designed to find early-type member galaxies within the virial radius and to obtain reliable velocity dispersion. We explain our selection scheme and preliminary results of the spectra. We also compare the dynamical mass estimate inferred from the velocity dispersion with the WL mass.

• Journal of Positioning, Navigation, and Timing
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• v.11 no.4
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• pp.269-277
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• 2022

In this paper, we overview the system development status of the national maritime precise point positioning-real-time kinematic (PPP-RTK) service in Korea, also known as the Precise POsitioning and INTegrity monitoring (POINT) system. The development of the POINT service began in 2020, and the open service is scheduled to start in 2025. The architecture of the POINT system is composed of three provider-side facilities-a reference station, monitoring station, and central control station-and one user-side receiver platform. Here, we propose the detailed functionality of each component considering unidirectional broadcasting of augmentation data. To meet the centimeter-level user positioning accuracy in maritime coverage, new reference stations were installed. Each reference station operates with a dual receiver and dual antenna to reduce the risk of malfunctioning, which can deteriorate the availability of the POINT service. The initial experimental results of a testbed from corrections generated from the testbed network, including newly installed reference stations, are presented. The results show that the horizontal and vertical accuracies satisfy 2.63 cm and 5.77 cm, respectively. For the purpose of (near) real-time broadcasting of POINT correction data, we designed a correction message format including satellite orbit, satellite clock, satellite signal bias, ionospheric delay, tropospheric delay, and coordinate transformation parameters. The (near) real-time experimental setup utilizing (near) real-time processing of testbed network data and the designed message format are proposed for future testing and verification of the system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.4
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• pp.169-176
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• 2021

Maritime monitoring requirements have been beyond human operators capabilities due to the broadness of the coverage area and the variety of monitoring activities, e.g. illegal migration, or security threats by foreign warships. Abnormal vessel movement can be defined as an unreasonable movement deviation from the usual trajectory, speed, or other traffic parameters. Detection of the abnormal vessel movement requires the operators not only to pay short-term attention but also to have long-term trajectory trace ability. Recent advances in deep learning have shown the potential of deep learning techniques to discover hidden and more complex relations that often lie in low dimensional latent spaces. In this paper, we propose a deep autoencoder-based clustering model for automatic detection of vessel movement anomaly to assist monitoring operators to take actions on the vessel for more investigation. We first generate gridded trajectory images by mapping the raw vessel trajectories into two dimensional matrix. Based on the gridded image input, we test the proposed model along with the other deep autoencoder-based models for the abnormal trajectory data generated through rotation and speed variation from normal trajectories. We show that the proposed model improves detection accuracy for the generated abnormal trajectories compared to the other models.