• Journal of Korean Society for Geospatial Information Science
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• v.24 no.1
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• pp.121-128
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• 2016

Many studies are focused on image data and classifier for comparison or improvement of classification accuracy. Therefore studies are needed aspect of the training samples on supervised classification which depend on reference data or skill of analyst. This study tries to assess usability of field spectra as training samples on supervised classification. Classification accuracies of hyperspectral and multispectral images were assessed using training samples from image itself and field spectra, respectively. The results shown about 90% accuracy with training sample collected from image. Using field spectra as training sample, accuracy was decreased 10%p for hyperspectral image, and 20%p for multispectral image. Especially, some classes shown very low accuracies due to similar spectral characteristics on multispectral image. Therefore, field spectra might be used as training samples on classification of hyperspectral image, although it has limitation for multispectral image.

• Journal of Korea Multimedia Society
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• v.13 no.2
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• pp.185-195
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• 2010

In this paper, we propose an efficient inter and intra prediction algorithms for fast encoding of H.264/AVC. First, inter prediction mode decision method decides early using temporal/spatial correlation information and pixel direction information. Second, intra prediction mode decision method selects block size judging smoothness degree with inner/outer pixel value variation and decides prediction mode using representative pixel and reference pixel. Lastly, adaptive motion search region restriction sets search region using mode information of neighboring block and predicted motion vector. The experimental results show that proposed method can achieve about 18~53% reduction compared with the existing JM 14.1 in the encoding time. In RD performance, the proposed method does not cause significant PSNR value losses while increasing bitrates slightly.

• Korean Journal of Optics and Photonics
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• v.15 no.1
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• pp.39-45
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• 2004

A computer simulation about removal of the 0-th order diffraction is achieved by using numerical reconstruction in digital holography and the Fourier transform method. A light intensity distribution hologram is generated through numerical calculation of the interference pattern. Additionally a phase hologram without the 0-th order diffraction is generated. The removal function for elimination of the 0-the order diffraction is introduced and the numerical reconstructions with several conditions for the removal of the 0-th order diffraction and the production of high quality numerically reconstructed images are tested and compared. The removal function is proven to be more effective at the suppression of the 0-th order diffraction compared with the DC suppression method.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.4
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• pp.31-41
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• 2009

IEEE 802.11e proposed by IEEE 802.11 working group to guarantee QoS has contention based EDCA and contention free based HCCA. HCCA, a centralized polling based mechanism of 802.11e, needs a scheduling algorithm to allocate the network resource efficiently. The existing standard scheduler, however, is inefficient to support for QoS guarantee for real-time service having VBR traffic. To improve these limit, in this paper, we First, we propose priority polling algorithm which additionally considers the size of MSI and TXOP based on EDD algorithm to increase number of QSTAs. We also propose a dual token bucket TXOP allocation algorithm to reduce congestion caused by stations which enters network with considerable delay variance. TSPEC parameters, Maximum Burst Size (MBS) and Peak Data Rate (PR), are applied to design depth and token generation rate of two buckets. Simulation results show that the proposed algorithm has much higher performance compared with reference and SETT-EDD scheduler in terms of throughput and delay.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.87-100
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• 2005

In this paper, we propose a new selective temporal error concealment algerian best suited for H.264/AVC. The proposed algorithm performs selective temporal error concealment depending on whether the lost block is at background or foreground. It the corrupted macroblock is decided as at background, then the simple temporal replacement is performed. Also we propose replacing a lost block at foreground with the selective average of respectively estimated blocks from the multiple reference frames. This paper supposes error-corrupted H.264/AVC video bitstreams over CDMA2000 (or UMTS) air interface. It is shown that under Flexible Macroblock Ordering (FMO) coding of H.264/AVC, the proposed algorithm provides PSNR gain up to 1.18dB compared to built-in algorithm in the K264/AVC test model. In addition, the proposed error concealment method has average PSNR improvement of 0.33dB compared with that under N-slice coding mode. The proposed algorithm also provides better subjective video quality than other conventional error concealment algorithms.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.999-1008
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• 2002

XML is emerging as a standard data format to exchange and to present data on the Web. There are increasing needs to efficiently store and to query XML data. In this paper. we propose a new schema transformation algorithm based on a common structure extracting technique from XML documents. The common structure is shared by all XML documents referenced by DTD and the uncommon structure is ununiformly appeared on all XML documents referenced by DTD. Based on the extracted common and uncommon structures, we transform XML DTD into relational database schema. We conduct a performance evaluation based on the number of the generated tables, the size of the record, query processing time and the number of joins on the query. The performance of our algorithm is compared with the existing algorithms, then in most cates, our algorithm is better than the existing ones with respect to the number of the generated tables and appearance of NULL values in the tables.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.1
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• pp.71-79
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• 2014

Most researches have created the impervious surface map by using low-spatial-resolution satellite imagery and are inefficient to generate the object-based impervious map with a broad area. In this study, segment-based impervious surface mapping algorithm is proposed using the RapidEye satellite imagery in order to map impervious area. At first, additional bands are generated by using TOA reflectance conversion RapidEye data. And then, shadow and water class are extracted using training data of converted reflectance image. Object-based impervious surface can be generated by spectral mixture analysis based on land cover map of Ministry of Environment with medium scale, in the case of other classes except shadow and water classes. The experiment shows that result by our method represents high classification accuracy compared to reference data, quantitatively.

• The Transactions of the Korea Information Processing Society
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• v.4 no.2
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• pp.552-562
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• 1997

This paper proposes a formal method on confromance testing for INAP(AIN) test sequence generation by optimization technique.In order to implement and prove the dffectiveness of the proposed method,we specify the SRSM of INAP protocol SRF in SDL and generate I/O FSM by using our S/W tool. We generate an opti-mal test sequence by applying our method our method to this reference I/O FSM. We prove experimentally that the length of the generated test sequence by our method is more effective and shorter(i.e 32% improved)than the one geverated by UIO method,and estimate that The test coverage space of our test sequence is larger that of UIO method.

• Composites Research
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• v.23 no.6
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• pp.61-66
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• 2010

In this paper, the variation of mechanical properties of T800 carbon/epoxy composites according to the forming pressure, which was referred to previous studies on a filament winding process, were investigated. The specimens of all the tests were fabricated by an autoclave de-gassing molding process controlling forming pressure (absolute pressures of 0.1MPa, 0.3MPa, 0.7MPa including vacuum) and water jet cutting after fabricating composite laminates. Various tensile tests were performed for in-plane properties and interlaminar properties were also measured by using Iosipescu test jig. Fiber volume fraction was measured to correlate the property variation and the forming pressure. This properties are expected to be utilized in the design of Type III pressure vessel for hydrogen vehicles which uses the same carbon fiber (T800 carbon fiber) for the filament winding process.

• Journal of Korea Port Economic Association
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• v.26 no.4
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• pp.219-246
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• 2010

Countries around the world are propelling policies and strategies to strengthen the competitiveness of their own ports as they recognize the roles and importance of the ports in the international trade and logistics. The main objective of this study is to compare efficiencies of major container ports and analyze the factors that affect the efficiencies in the three regions of East Asia, Europe, and North America, which cover most of world container shipping. We employ DEA models in analyzing the efficiencies of 45 container ports using 5 input and 2 output variables. We also carry out regression analyses to estimate the impacts of each factor on the throughput (TEU), overall technical efficiency (OTE), pure technical efficiency (PTE), and scale efficiency (SE). The analysis results show that East Asian ports, despite being smaller in average size, make greater output and achieve higher technical and scale efficiencies than European or North American ports.