• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.120-131
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• 2020

Water body detection using remote sensing based on machine interpretation of satellite image is efficient for managing water resource, drought and flood monitoring. In this study, water body detection with SAR satellite image based on machine learning was performed. However, non water body area can be misclassified to water body because of shadow effect or objects that have similar scattering characteristic comparing to water body, such as roads. To decrease misclassifying, 8 combination of morphology open filtered band, DEM band, curvature band and Cosmo-SkyMed SAR satellite image band about Mokpo region were trained to semantic segmentation machine learning models, respectively. For 8 case of machine learning models, global accuracy that is final test result was computed. Furthermore, concordance rate between landcover data of Mokpo region was calculated. In conclusion, combination of SAR satellite image, morphology open filtered band, DEM band and curvature band showed best result in global accuracy and concordance rate with landcover data. In that case, global accuracy was 95.07% and concordance rate with landcover data was 89.93%.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.3
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• pp.64-76
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• 2009

Adaptive Random Testing through Iterative Partitioning(IP-ART) is one of Adaptive Random Testing(ART) techniques. IP-ART uses an iterative partitioning method for input domain to improve the performances of early-versions of ART that have significant drawbacks in computation time. Another version of IP-ART, named with EIP-ART(IP-ART with Enlarged Input Domain), uses virtually enlarged input domain to remove the unevenly distributed parts near the boundary of the domain. EIP-ART could mitigate non-uniform test case distribution of IP-ART and achieve relatively high performances in a variety of input domain environments. The EIP-ART algorithm, however, have the drawback of higher computation time to generate test cases mainly due to the additional workload from enlarged input domain. For this reason, a revised version of IP-ART without input domain enlargement needs to improve the distribution of test cases to remove the additional time cost. We explore three smoothing algorithms which influence the distribution of test cases, and analyze to check if any performance improvements take place by them. The simulation results show that the algorithm of a restriction area management achieves better performance than other ones.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.48-56
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• 2010

Recently, we need to dramatically speed up real-time video encoding and decoding on mobile devices because complexity of video CODEC is significantly increasing along with the demand for multimedia service of high-quality and high-definition videos by users. A variety of research is conducted for parallelism of video processing using newly developed multi-core platforms. In this paper, we propose a method of parallelism based on slice partition of video compression CODEC. We propose a novel concept of a parallel slice for parallelism and propose a new coding order to be adequate to the parallel slice which keeps high coding efficiency. To minimize synchronization time of multiple parallel slices, we also propose a synchronization method to determinate whether the parallel slice could be independently decoded or not. Experimental results shows that we achieved 27.5% (40.7%) speed-up by parallelism with bit-rate increase of 3.4% (2.7%) for CIF sequences (720p sequences) by implementing the proposed algorithm on the H.264/AVC.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.6
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• pp.39-47
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• 2010

A research of image-based articulated pose estimation has some problems such as detection of human feature, precise pose estimation, and real-time performance. In particular, various methods are currently presented for recovering many joints of human body. We propose the novel numerical inverse kinematics improved with the UKF(unscented Kalman filter) in order to estimate the human pose in real-time. An existing numerical inverse kinematics is required many iterations for solving the optimal estimation and has some problems such as the singularity of jacobian matrix and a local minima. To solve these problems, we combine the UKF as a tool for optimal state estimation with the numerical inverse kinematics. Combining the solution of the numerical inverse kinematics with the sampling based UKF provides the stability and rapid convergence to optimal estimate. In order to estimate the human pose, we extract the interesting human body using both background subtraction and skin color detection algorithm. We localize its 3D position with the camera geometry. Next, through we use the UKF based numerical inverse kinematics, we generate the intermediate joints that are not detect from the images. Proposed method complements the defect of numerical inverse kinematics such as a computational complexity and an accuracy of estimation.

• The Journal of the Acoustical Society of Korea
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• v.23 no.1
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• pp.8-16
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• 2004

An inversion method is presented for the determination of the compressional wave speed, compressional wave attenuation, thickness of the sediment layer and density as a function of depth for a horizontally stratified ocean bottom. An experiment for estimating those properties was conducted in the shallow water of South Sea in Korea. In the experiment, a light bulb implosion and the propagating sound were measured using a VLA (vertical line array). As a method for estimating the geoacoustic properties, a coherent broadband matched field processing combined with Genetic Algorithm was employed. When a time-dependent signal is very short, the Fourier transform results are not accurate, since the frequency components are not locatable in time and the windowed Fourier transform is limited by the length of the window. However, it is possible to do this using the wavelet transform a transform that yields a time-frequency representation of a signal. In this study, this transform is used to identify and extract the acoustic components from multipath time series. The inversion is formulated as an optimization problem which maximizes the cost function defined as a normalized correlation between the measured and modeled signals in the wavelet transform coefficient vector. The experiments and procedures for deploying the light bulbs and the coherent broadband inversion method are described, and the estimated geoacoustic profile in the vicinity of the VLA site is presented.

• Journal of KIISE
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• v.43 no.12
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• pp.1437-1457
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• 2016

In outsourced databases, the cloud provides an authorized user with querying services on the outsourced database. However, sensitive data, such as financial or medical records, should be encrypted before being outsourced to the cloud. Meanwhile, k-Nearest Neighbor (kNN) query is the typical query type which is widely used in many fields and the result of the kNN query is closely related to the interest and preference of the user. Therefore, studies on secure kNN query processing algorithms that preserve both the data privacy and the query privacy have been proposed. However, existing algorithms either suffer from high computation cost or leak data access patterns because retrieved index nodes and query results are disclosed. To solve these problems, in this paper we propose a new kNN query processing algorithm on the encrypted database. Our algorithm preserves both data privacy and query privacy. It also hides data access patterns while supporting efficient query processing. To achieve this, we devise an encrypted index search scheme which can perform data filtering without revealing data access patterns. Through the performance analysis, we verify that our proposed algorithm shows better performance than the existing algorithms in terms of query processing times.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.56-65
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• 2016

In this paper, in order to reduce the delay and area of the partial product accumulation (PPA) of the parallel decimal multiplier, a tree architecture that composed by multi-operand decimal CSAs and improved CLA is proposed. The proposed tree using multi-operand CSAs reduces the partial product quickly. Since the input range of the recoder of CSA is limited, CSA can get the simplest logic. In addition, using the multi-operand decimal CSAs to add decimal numbers that have limited range in specific locations of the specific architecture can reduce the partial products efficiently. Also, final BCD result can be received faster by improving the logic of the decimal CLA. In order to evaluate the performance of the proposed partial product accumulation, synthesis is implemented by using Design Complier with 180 nm COMS technology library. Synthesis results show the delay of the proposed partial product accumulation is reduced by 15.6% and area is reduced by 16.2% comparing with which uses general method. Also, the total delay and area are still reduced despite the delay and area of the CLA are increased.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.6
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• pp.715-720
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• 2016

This paper proposes a PWM (Pulse Width Modulation) voltage mode DC-DC step-up converter for portable devices. The converter, which is operated with a 1 MHz switching frequency, is capable of reducing the mounting area of passive devices, such as inductor and capacitor, and is suitable for compact mobile products. This step-up converter consists of a power stage and a control block. The circuit elements of the power stage are an inductor, output capacitor, MOS transistors Meanwhile, control block consist of OPAMP (operational amplifier), BGR (band gap reference), soft-start, hysteresis comparator, and non-overlap driver and some protection circuits (OVP, TSD, UVLO). The hysteresis comparator and non-overlapping drivers reduce the output ripple and the effects of noise to improve safety. The proposed step-up converter was designed and verified in Magnachip/Hynix 0.18um 1-poly, 6-metal CMOS process technology. The output voltage was 5 V with a 3.3 V input voltage, output current of 100 mA, output ripple less than 1% of the output voltage, and a switching frequency of 1 MHz. These designed DC-DC step-up converters could be applied to the Personal Digital Assistants(PDA), cellular Phones, Laptop Computer, etc.

• Archives of design research
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• v.20 no.3 s.71
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• pp.119-128
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• 2007

With the development of digital technologies, CAID became an essential part in the industrial design process. Creating photo-realistic images from a virtual scene with 3D models is one of the specialized task for CAID users. This task requires a complex interface of setting the positions and the parameters of camera and lights for optimal rendering results. However, the user interface of existing CAID tools are not simple for designers because the task is mostly accomplished in a parameter setting dialogue window. This research address this interface issues, in particular the issues related to lighting, by developing and evaluating TLS(Tangible Lighting Studio) that uses Augmented Reality and Tangible User Interface. The interface of positioning objects and setting parameters become tangible and distributed in the workspace to support more intuitive rendering task. TLS consists of markers, and physical controller, and a see-through HMD(Head Mounted Display). The user can directly control the lighting parameters in the AR workspace. In the evaluation experiment, TLS provide higher effectiveness, efficiency and user satisfaction compared to existing GUI(Graphic User Interface) method. It is expected that the application of TLS can be expanded to photography education and architecture simulation.

• The KIPS Transactions:PartC
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• v.17C no.4
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• pp.307-314
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• 2010

Recently, it is proved that contactless smart-card based RFID tags, which is used for proximity authentication, are vulnerable to relay attacks with various location-based attacks such as distance fraud, mafia fraud and terrorist fraud attacks. Moreover, distance bounding protocols have been researched to prevent these relay attacks that can measure the message transmitted round-trip time between the reader and the tag. In 2005, Hancke and Kuhn first proposed an RFID distance bounding protocol based on secure hash function. However, the Hancke-Kuhn protocol cannot completely prevent the relay attacks because an adversary has (3/4)$^n$ attack success probability. Thus, this paper proposes a new distance-bounding protocol for light-weight RFID systems that can reduce to (5/8)$^n$ for the adversary's attack success probability. As a result, the proposed protocol not only can provide high-space efficient based on a secure hash function and XOR operation, but also can provide strong security against the relay attacks because the adversary's attack success probability is optimized to (5/8)$^n$.