• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.5
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• pp.585-596
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• 2012

PVDF(poly vinylidene fluoride) and P(VDF-TrFE)(poly vinylidene fluoride-tetrafluoroethylene) are the typical piezoelectric polymers with unique properties. Even they are inferior to conventional piezoelectric ceramics PZT in electromechanical conversion efficiency and interior loss, though they are superior in receiving sensitivity and frequency bandwidth. Their acoustic impedances are relatively close to water or biological tissue and it is easier to make thin film than other piezoelectric materials. Futhermore, the film is so flexible that it is easy to attach on a complex surface. Those properties are suitable for the ultrasound transducers which are useful for medical and biological application, so that various types of polymer transducers have been developed. In this paper, several important considerations for design and fabrication of piezoelectric polymer transducers were described and their effect on the transducer performance were demonstrated through the KLM model analysis. Then, it was briefly reviewed about the structures of the polymer transducers developed for obtaining images as well as the characteristics of the images in several important medical and biological application fields.

• Journal of Korea Multimedia Society
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• v.16 no.1
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• pp.75-86
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• 2013

This paper presents a technique to implement embedded systems using interrupts of the one-chip microcontroller with many peripherals based on a multiple finite state machines model. The multiple finite state machine model utilizes the structure of FSMD used for hardware design and the features of flow control by interrupts. The main finite state machine corresponds to the main program and the sub-state machines corresponds to the interrupt subroutines. Therefore, interrupts from the peripherals can be processed immediately in the sub-state machines. The request and reply variables are used to interface between the finite state machines. Additional operating system is not necessary for the context switching between the main state machine and the sub-state machine, because the flow-control caused by interrupt can be replaced with the switching. An embedded system modeled on multiple finite state machine with ASM charts can be easily implemented by the conversion of ASM charts into C-language programs. This implementation technique can be easily adopted to the hardware oriented embedded systems because of the detail description of the model and the fast response to the interrupt events in the sub-state machine.

• Smart Media Journal
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• v.6 no.2
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• pp.26-32
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• 2017

In this paper, we implement a signal-detecting electric circuit based LED lighting control system which is essential in NUI technology using EPIC converting surrounding earth electric field disturbance signals to electric potential signals. We used signal-detecting electric circuits which was developed to extract individual signal for each EPIC sensor while conventional EPIC-based development equipments provide limited forms of signals. The signals extracted from our developed circuit contributed to better performance as well as flexiblity in processes of feature extracting stage and pattern recognition stage. We designed a system which can control the brightness and on/off of LED lights with four hand gestures in order to justify its applicability to real application systems. We obtained faster pattern classification speed not only by developing an instruction system, but also by using interface control signals.

• The Journal of the Korea Contents Association
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• v.9 no.9
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• pp.68-79
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• 2009

A variance map can be used to detect and distinguish texts from background in images. However, previous variance maps work at one level and they suffer a limitation in dealing with varieties in text size, slant, orientation, translation, and color. We present a method for robustly segmenting text regions in complex color Web images using two-level variance maps. The two-level variance maps work hierarchically. The first level finds the approximate locations of text regions using global horizontal and vertical color variances with the specific mask sizes. The second level then segments each text region using intensity variance with a local mask size, which is determined adaptively. By the second process, backgrounds tend to disappear in each region and segmentation can be accurate. Highly promising experimental results have established the effectiveness of our approach.

• The KIPS Transactions:PartA
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• v.15A no.6
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• pp.335-344
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• 2008

We propose an adaptive garbage collection technique for hybrid flash memory which has both SLC and MLC. Since SLC area is fast and MLC area has low cost, the proposed scheme utilizes the SLC area as log buffer and the MLC area as data block. Considering the high write cost of MLC flash, the garbage collection for the SLC log buffer moves a page into the MLC data block only when the page is cold or the page migration invokes a small cost. The other pages are moved within the SLC log buffer. Also it adjusts the parameter values which determine the operation of garbage collection adaptively considering I/O pattern. From the experiments, we can know that the proposed scheme provides better performance compared with the previous flash management schemes for the hybrid flash and finds the parameter values of garbage collection close to the optimal values.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.595-612
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• 2009

The early test can greatly reduce the cost of error correction for system development. It is still important in SOA based service system. However, the existing methods of test case generation for SOA have limitations which are restricted to only web service using XML. Therefore, this paper proposes a method of test case generation using BPMN-based model reduction for service system. For minimizing test effort, an existing BPM is transformed into S-BPM which is composed of basic elements of workflow. The process of test case generation starts with making S-BPM concerning the target service system, and transforms the target service system into directed graph. And then, we generate several service scenarios applying scenario searching algorithm and extract message moving information. Applying this method, we can obtain effective test cases which are even unlimited to web service. This result is the generation of test case which is reflected in the business-driven property of SOA.

• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.6
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• pp.748-753
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• 2012

In this paper, Face recognition algorithm is designed based on optimized pRBFNNs pattern classifier using three-dimensional scanner. Generally two-dimensional image-based face recognition system enables us to extract the facial features using gray-level of images. The environmental variation parameters such as natural sunlight, artificial light and face pose lead to the deterioration of the performance of the system. In this paper, the proposed face recognition algorithm is designed by using three-dimensional scanner to overcome the drawback of two-dimensional face recognition system. First face shape is scanned using three-dimensional scanner and then the pose of scanned face is converted to front image through pose compensation process. Secondly, data with face depth is extracted using point signature method. Finally, the recognition performance is confirmed by using the optimized pRBFNNs for solving high-dimensional pattern recognition problems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1162-1169
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• 2007

In this paper, we proposed a container identifier recognition method for containers used in harbors. After converting a real container image to a gray image, edges are detected from the gray image applying Prewitt mask and candidate identifier area is extracted using morphological features of individual identifier for identifying containers. Because noises are included in the extracted candidate identifier area, noises are eliminated and each identifier is separated using 4-directional edge tracking algorithm and Grassfire algorithm. Each identifier in the noise-free candidate identifier area is recognized using FCM-based row RBF network for discriminating containers. We used 300 real container images for experiment to evaluate the performance of the proposed method, and we could verify the proposed method is better than a conventional method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.10
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• pp.1845-1851
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• 2007

Background noise and room reverberation are two causes of degradation in speech in listening situations. Many algorithms developed to enhance reverberant speech. In this paper we propose a dereverberation method for enhancement of speech using modified the linear prediction(LP) residual in reverberant room condition. The proposed dereberberation method based on the fact that the signification excitation of the vocal tract system takes place at the instant of glottal closure in voiced speech. Our method used delay information form each sensor, and we need reverberant signals from 3 sensors. We obtain a new LP residual signal using modified IP residual combination which derived form weighting of the LP residual and the Hilbert transform of LP residual. The nature of the coherently added Hilbert envelop has several large amplitude spikes because of the effects of noise and reverberation. This residual of the clean speech is used to excite the time-varying all-pole filter to obtain the enhanced speech. We achieved simulation of proposed algorithm for performance analysis in reverberation environment. The proposed algorithm improves substantially the quality of reverberant speech.

• Journal of Software Engineering Society
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• v.25 no.1
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• pp.1-9
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• 2012

RFID systems have been widely used in various fields such as logistics, distribution, food, security, traffic and others. A RFID middleware, one of the key components of the RFID system, perform an important role in many functions such as filtering, grouping, reporting tag data according to given user specifications and so on. However, manual test data generation is very hard because the inputs of the RFID middleware are generated according to the RFID middleware standards and complex encoding rules. To solve this problem, in this paper, we propose a black box test technique based on RFID middleware standards. Firstly, we define ten types of input conversion rules to generate new test data from existing test data based on the standard specifications. And then, using these input conversion rules, we generate various additional test data automatically. To validate the effectiveness of generated test data, we measure coverage of generated test data on actual RFID middleware. The results show that our test data achieve 78% statement coverage and 58% branch coverage in the classes of filtering and grouping, 79% statement coverage and 64% branch coverage in the classes of reporting.