• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.381-388
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• 2014

Our aim was to simulate ocean waves in a small-size wave flume and observe the motion of a cylindrical floating body placed in an offshore environment. To precisely visualize the oscillation of the body, a set of light-emitting diode illuminators and high-speed charge-coupled device camera were installed in the flume. Spectral analysis was performed of the movement of the floating body. The wave generator and absorbers worked well to simulate stable regular waves. As the period of the oncoming waves changed, the movement of the floating body substantially differed when tethered to a tension-leg mooring cable. In particular, when connected to the tension-leg mooring cable, the natural frequency of the floating body suddenly appeared at 0.391 Hz as the wave period was increased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.11
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• pp.101-106
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• 2005

A ground penetrating image radar (GPR) using an ultra wideband (UWB)impulse waveform is developed for non destructive detection of metallic pipelines buried under the ground. Dielectric constant of test field is measured and then a GPR system is designed for better detection up to 1 meter deep. By considering total path loss, volume of complete system, and resolution, upper and lower frequencies are chosen. First, a UWB impulse for the frequency bandwidth of the impulse is chosen with rising time less than 1 ns, and then compact planar UWB dipole antenna suitable for frequency bandwidth of a UWB impulse is designed. Also, to receive reflected signals, a digital storage oscilloscope is used. For measurement, a monostatic technique and a migration technique are used. For visualizing underground targets, simple image processing techniques of A-scan removal and B-scan average removal are applied. The prototype of the system is tested on a test field in wet clay soil and it is shown that the developed system has a good ability in detecting underground metal objects, even small targets of several centimeters.

• The Journal of the Korea Contents Association
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• v.12 no.1
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• pp.1-8
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• 2012

In this paper, a method of determining the optimal threshold in image binarization for the marker recognition is suggested to resolve the problem that the performances of marker recognition are quite different according to the changes of indoor lighting. The suggested method determines the optimal threshold by considering the average brightness, the standard deviation and the maximum deviation of video image under the various indoor lighting circumstances, such as bright light, dim light, and shadow by unspecified obstacles. In particular, the recognition under the gradation lighting by shadow is improved by applying the weighted value that depends on the brightness of image. The suggested method is experimented to process $720{\times}480$ resolution video images under the various lighting environments, and it shows the fast and high performance, which is suitable for mobile indoor navigation.

• Journal of Korea Multimedia Society
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• v.16 no.4
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• pp.483-492
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• 2013

SURF is an algorithm which extracts feature points and generates their descriptors from input images, and it is being used for many applications such as object recognition, tracking, and constructing panorama pictures. Although SURF is known to be robust to changes of scale, rotation, and view points, it is hard to implement it in real time due to its complex and repetitive computations. Using 3.3 GHz Pentium, in our experiment, it takes 240ms to extract feature points and create descriptors in a VGA image containing about 1,000 feature points, which means that software implementation cannot meet the real time requirement, especially in embedded systems. In this paper, we present a hardware architecture that can compute the SURF algorithm very fast while consuming minimum hardware resources. Two key concepts of our architecture are parallelism (for repetitive computations) and efficient line memory usage (obtained by analyzing memory access patterns). As a result of FPGA synthesis using Xilinx Virtex5LX330, it occupies 101,348 LUTs and 1,367 KB on-chip memory, giving performance of 30 frames per second at 100 MHz clock.

• The Journal of the Korea Contents Association
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• v.8 no.11
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• pp.33-40
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• 2008

The application of OCR moves from traditional formatted documents to the web document and natural scene images. It is usual that the new applications use not only standard fonts of Myungjo and Godic but also various fonts. The conventional databases which have mainly been constructed with standard fonts have limitations in applying to the new applications. In this paper, we generate 243 image samples for each of 2350 Hangul character classes which differs in font size, quality, and resolution. Additionally each sample was varied according to binarization threshold and rotational transformation. Through this process 2187 samples were generated for each character class. Totally 5,139,450 samples constitutes the printed Hangul character database called the PHD08. In addition, we present the characteristics and recognition performance by an commercial OCR software.

• The Journal of the Korea Contents Association
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• v.11 no.5
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• pp.205-215
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• 2011

Films are sensitive to ultraviolet rays and in contrast, digital camera sensors are extremely sensitive to infrared rays due to the differences in spectral characteristics. As a result, all digital cameras that use CCD or CMOS are equipped with IR Cut-Off Filter on the overall sensor. Complete block out of infrared rays is ideal, but the actual experiment results showed that infrared rays were not being blocked out completely. Infrared permeability was also different for each camera. Therefore, this study aims to analyze the effect of the minute quantities of infrared rays, which get transmitted due to mechanical properties of IR Cut-Off Filters that are installed on digital cameras, on digital picture images. The results obtained by carrying out a comparative analysis of a UV Filter (infrared transmitting state) and a UV-IR Filter (infrared blocked out state) are as follows. It was confirmed that the minute quantities of infrared rays do affect dynamic range and resolution to some extent, despite the little or no difference in noise and color reproduction.

• Korean Journal of Environment and Ecology
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• v.18 no.2
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• pp.231-235
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• 2004

Landsat satellite images were analyzed to study vegetation change patterns of warm-temperate forests from 1991 to 2002 in Wando. For this purpose, Landsat TM satellite image of 1991 and Landsat ETM image of 2002 were used for vegetation classification using ENVI image processing software. Four different forest types were set as a classification criteria; evergreen broadleaf, evergreen conifer, deciduous broadleaf, and others. Unsupervised classification method was applied to classily forest types. Although it was impossible to draw exact forest types in rocky areas because of differences in data detection time and rough resolution of image, 2002 data revealed that total 2,027ha of evergreen broadleaf forests were growing in Wando. Evergreen broadleaves and evergreen conifers increased in total areas compared to 11 years ago, but there was sharp decrease in deciduous broadleaves. GIS-based management system for warm-temperate forest was done using Arc/Info. Geographic and attribute database of Wando such as vegetation, soils, topography, land owners were built with Arc/Info and ArcView. Graphic user interface which manages and queries necessary data was developed using Avenue.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.27-34
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• 2007

In this paper device driver for camera capture in hand held mobile system is implemented based on microsoft windows CE operating system. We also study the storage device driver based on the FAT fie system by using NAND flash memory as a storage device. We use the MBA2440 PDA board for implementing the hardware for image capture by using CMOS camera module producted by PixelPlus company. This camera module has VGA $640{\times}480$ pixel resolution. We also make application program which can be cooperated with the device driver for testing its performance, for example image capture speed and quality of captured image. We check that the application can be cooperated well not only with the device driver for camera capture but also with the device driver for FAT file system designed especially for the NAND flash memory.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.369-372
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• 2018

This paper suggests non-parallel-voice-conversion network conversing voice between unmapped voice pair as source voice and target voice. Conventional voice conversion researches used learning methods that minimize spectrogram's distance error. Not only these researches have some problem that is lost spectrogram resolution by methods averaging pixels. But also have used parallel data that is hard to collect. This research uses PPGs that is input voice's phonetic data and a GAN learning method to generate more clear voices. To evaluate the suggested method, we conduct MOS test with GMM based Model. We found that the performance is improved compared to the conventional methods.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.3
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• pp.247-254
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• 2017

Optical Coherence Tomography (OCT) is a non-invasive imaging method that utilizes the optical scattering and interference for visualizing the surface as well as cross-sectional structures of tissue. OCT has been used for diagnosing diseases in early stage in various medical fields, but an application in cosmetics is still at early stage. In this study, OCT was adopted to evaluate skin texture and wrinkle. Results showed similar patterns of evaluation with PRIMOS in the assessment using replica. In addition, OCT produced smaller errors at different angles compared to the PRIMOS in the assessment using 3-dimensional models of wrinkles. The resolution of the image was also high enough to differentiate the images of before and after the application of makeup products. Possible use of OCT in the evaluation of fine wrinkle assessment was studied in this research. Further development of methods is necessary to provide more evidences of the effectiveness.