• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.2
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• pp.192-197
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• 2012

In this paper, a non-contact microwave technique was presented to detect the surface crack of the metals. An open-ended coaxial cable line was used as a sensor at 11 GHz, and the reflection coefficients were measured by scanning along the metal surface including artificial surface cracks. A parameter, the K value which was defined as the difference between maximum and minimum reflection coefficients, was measured and used to estimate the crack depth. A linear relationship between the K value and crack depth was found. This study showed that non-contact detection of the surface cracks of metals is possible using the open-ended coaxial line sensor at X-band.

• The KIPS Transactions:PartB
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• v.14B no.4
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• pp.241-248
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• 2007

An L-curve corner detection method is proposed for the determination of the regularization parameter in optical flow estimation. The method locates the positive peak whose curvature difference from the just right-hand negative valley is the maximum in the curvature plot of the L-curve. while the existing curvature-method simply finds the maximum in the plot. Experimental results show that RMSE of the estimated optical flow is greater only by 0.02 pixels-per-frame than the least in the average sense. The proposed method is also compared with an existing curvature-method and the adaptive pruning method, resulting in the optical flow estimation closest to the least RMSE.

• Journal of the Korea Society of Computer and Information
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• v.3 no.2
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• pp.69-76
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• 1998

To test all internal faults in the case that the number of Primary Input is N, we need patterns that are composed of PI's of maximum 2N. In this paper, we proposed the method to reduce a search space by dividing the multiple output circuit into subcircuit that is related with output. And this method, called PBM(Partition-Based Method), can generate a set of test pattern. The method can effectively generate a test pattern for evaluating all fault of circuit, because the length of input pattern is smaller than that of full circuit and PBM doesn't search any signal line that is not concerned with detecting fault.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6A
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• pp.577-582
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• 2008

In this paper, we present a scheme to overcome the worst case complexity of the sphere decoder. If the number of visited nodes reaches the threshold, the detected symbol vector is determined between two candidate symbol vectors. One candidate symbol vector is obtained from the demodulated output of ZF receiver which is initial stage of the sphere decoder. The other candidate symbol vector consists of two sub-symbol vectors. The first sub-symbol vector consists of lately visited nodes running from the most upper layer. The second one contains corresponding demodulated outputs of ZF receiver. Between these two candidate symbol vectors, the one with smaller euclidean distance to the received symbol vector is chosen as detected symbol vector. In addition, we show the upper bound of symbol error rate performance for the sphere decoder using the proposed scheme. In the simulation, the proposed scheme shows the significant reduction of the worst case complexity while having negligible SER performance degradation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.126-134
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• 2017

There have been numerous studies on extracting the R-peak from electrocardiogram (ECG) signals. However, most of the detection methods are complicated to implement in a real-time portable electrocardiograph device and have the disadvantage of requiring a large amount of calculations. R-peak detection requires pre-processing and post-processing related to baseline drift and the removal of noise from the commercial power supply for ECG data. An adaptive filter technique is widely used for R-peak detection, but the R-peak value cannot be detected when the input is lower than a threshold value. Moreover, there is a problem in detecting the P-peak and T-peak values due to the derivation of an erroneous threshold value as a result of noise. We propose a robust R-peak detection algorithm with low complexity and simple computation to solve these problems. The proposed scheme removes the baseline drift in ECG signals using an adaptive filter to solve the problems involved in threshold extraction. We also propose a technique to extract the appropriate threshold value automatically using the minimum and maximum values of the filtered ECG signal. To detect the R-peak from the ECG signal, we propose a threshold neighborhood search technique. Through experiments, we confirmed the improvement of the R-peak detection accuracy of the proposed method and achieved a detection speed that is suitable for a mobile system by reducing the amount of calculation. The experimental results show that the heart rate detection accuracy and sensitivity were very high (about 100%).

• Journal of Energy Engineering
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• v.28 no.3
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• pp.10-17
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• 2019

According to South Korea's policy of supplying eco-friendly hydrogen vehicles, related industries are actively conducting research on the development of hydrogen cars and hydrogen charging station infrastructure. On the other hand, there is a lack of empirical research and assessment of the risk of non-metallic materials (such as liners, seals, gaskets) for classified materials that directly affect the durability and reliability of hydrogen vehicles and hydrogen charging stations. In this study, the risk factors for liners and seals of non-metallic parts used in high-pressure hydrogen installations were derived using FMEA, and the RPN values were calculated by converting the severity, frequency of occurrence and degree of detection into scores. The maximum value of the RPN 600, minimum value 63, average value 278.5 was calculated and periodic control of the liner and seal was identified as important. In addition, through hydrogen soakage and oxygen aging tests for non-metallic rubber products, physical test values that can be used as basic data were presented.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.223-230
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• 2015

The objective of this study is to identify the radionuclide distribution in public water by carrying out the analysis of artificial radionuclides($^{134}Cs$, $^{137}Cs$, $^{239+240}Pu$), natural radionuclide($^{210}Pb$) and TOC in the lake Euiam sediment in Chuncheon, South Korea. The $^{134}Cs$ concentration in all lake sediments showed below MDA values, and the $^{137}Cs$ concentration in lake sediment were ranged from MDA to $8.79Bq{\cdot}kg^{-1}-dry$. The $^{137}Cs$ concentrations in surface sediment were reported to be 2.4 to $4.2Bq{\cdot}kg^{-1}-dry$. The lowest concentration of $^{137}Cs$ was reported at St. 4 and the highest concentration was reported at St. 3, respectively. The $^{239+240}Pu$ concentration in lake sediment were ranged from 0.049 to $0.47Bq{\cdot}kg^{-1}-dry$. The lowest concentration was reported at St. 2 and the highest concentration was reported at St. 3. The correlation(r) between the $^{239+240}Pu$ concentration and $^{137}Cs$ concentration in lake sediment presented higher values (0.54 to 0.97) and this suggests the behavior and origin of $^{137}Cs$ is identical to the $^{239+240}Pu$ in the sediment. The $^{134}Cs$ concentration below MDA value and the $^{239+240}Pu/^{137}Cs$ ratio(mean value of 0.041) indicated that the artificial radionuclides in the sediment were originated from global fallout by the atmospheric testing of nuclear weapons conducted by former USSR and U.S.A, but not from the Fukushima Daiichi NPP accident. The sedimentation rate derived from $^{210}Pb$ age-dating method at St. 2 is calculated to be $0.31{\pm}0.06cm{\cdot}y^{-1}$. This value is similar to the value ($0.41{\pm}0.05cm{\cdot}y^{-1}$) estimated from the $^{137}Cs$ maximum peak produced from early 1960's. The content of TOC in lake Euiam sediments varied from 0.20 to 13.01%. While the highest correlation between TOC and $^{137}Cs$ concentration in the sediment were found at St. 1, the others presented the low correlation.

• Journal of Korea Entertainment Industry Association
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• v.5 no.1
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• pp.127-133
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• 2011

Characters in natural image are an important information with various context. Previous work of character region detection algorithms is not detect of character region in case of image complexity and the surrounding lighting, similar background to character, so this paper propose an method of character region detection in natural image using edge and connected component by morphological reconstructions. Firstly, we detect edge using Canny-edge detector and connected component with local min/max value by morphological reconstructed-operation in gray-scale image, and labeling each of detected connected component elements. lastly, detected candidate of text regions was merged for generation for one candidate text region, Final text region detected by checking the similarity and adjacency of neighbor of text candidate individual character. As the results of experiments, proposed algorithm improved the correctness of character regions detection using edge and connected components.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.10
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• pp.6317-6321
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• 2014

Multimedia documents can be transferred quickly and easily across the Internet, and has attracted considerable interest in multimedia security and multimedia copyright protection. This paper proposes an animage watermarking scheme embedding a binary watermark image using Discrete Wavelet Transform (DWT) coefficients. The original image is transformed to the wavelet domain and decomposed in subbands. The binary watermark image, as a sequence of bits, is embedded into the middle frequency subbands. The original image is not needed to detect the watermark image. The proposed method detected fewer watermark bits but produced an approximately 10dB higher PSNR than the max/min method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.44-53
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• 2005

In this paper, a improved moving object detection algorithm for stable performance of surveillance system in case of iterative moving in limited area and rapidly illuminance change in background scene is proposed. The proposed algorithm is that background scenes are sampled for initializing background image then the sampled fames are divided by block and sum of graylevel value for each block pixel was calculated, respectively. The initialization of background image is that background frame is respectively reconstructed with selecting only the maximum graylevel value and the minimum graylevel value of blocks located at same position between adjacent frames, then reference images of background are set by the reconstructed background images. Moving object detecting is that the current image frame is divided by block then sum of graylevel value for each block pixel is calculated. If the calculated value is out of graylevel range of the initialized two reference images, it is decided with moving objects block, otherwise it is decided background. The evaluated results is that the error rate of the proposed method is less than the error rate of the existing methods from $0.01{\%}$ to $20.33{\%}$ and the detection rate of the proposed method is better than the existing methods from $0.17{\%}\;to\;22.83{\%}$.