• Journal of the Korean GEO-environmental Society
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• v.18 no.10
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• pp.23-34
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• 2017

As the electrical property of fully saturated soils is dependent on the pore water, it has been commonly used for the detection of the contamination into the ground. The objective of this study is to investigate the electrical characteristics according to the salinity and the lead concentration in fully saturated soils. Fresh water and saline water with the salinity of 1%, 2% and 3%, which are mixed with 6 different lead solutions with the range of 0~10 mg/L, are prepared in the cylindrical cell incorporated with sensors for measuring electrical resistance and time domain reflectometry signal. Then, the dried sands are water-pluviated into the cell. The electrical resistance and the time domain reflectometry signal are used to estimate the electrical conductivity. Test results show that electrical conductivity determined from electrical resistance at the frequency of 1 kHz continuously increases with an increase in the lead concentration, thus it may be used for the estimation of the contaminant level. In addition, the electrical conductivity estimated by the time domain reflectometry changes even at very low concentration of lead, the variation rate decreases as the lead concentration increases. Thus, the time domain reflectometry can be used for the investigation of the heavy metal leakage. This study demonstrates that complementary characteristics of electrical resistance and time domain reflectometry may be used for the detection of the leakage and contamination of heavy metal in coastal and marine environments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.4
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• pp.1342-1347
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• 2010

Various researches have been studied on WSN(wireless sensor network) for barbed wire entanglements surveillance applications such as industry facilities, security area, prison, military area, airport, etc. Currently, barbed wire entanglements surveillance is formed wire sensor network environment. Traditional wire sensor network guarantee high data transmission rate. Therefore, wire sensor network use fast fourier transform of data of high transmission rate for extraction of feature parameter. However, wireless sensor network in comparison with wire sensor network has very low data transmission rate. Therefore, wireless sensor network doesn't use fast fourier transform of wire sensor network for extraction of feature parameter. In this paper, proposed method use 1 level approximation coefficient of DTW(dynamic time-warped) algorithms based on DWT(discrete wavelet transform) for extraction of detection feature parameter and classification feature parameter for barbed wire entanglements surveillance. l level approximation coefficient have time information and frequency information of signal. Therefore, Dynamic time-warped algorithms based on discrete wavelet transform improve detection and classification of target rather than using energy of signal.

• Journal of the Economic Geographical Society of Korea
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• v.23 no.1
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• pp.1-17
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• 2020

The study aims to identify economic interdependencies between regions and define functional economic areas of Korea by analyzing inter-firm transaction networks. Previous research has relied on pre-given administrative boundaries or cultural homogeneity and used data such as commuting, population movement, and cargo flows which could not fully explain economic activities. To overcome the limitations, this study applies a community detection method to inter-firm transaction networks derived from the CRETOP+ database of Korean corporate data. The novel dataset and the network analysis enables us to identify Korea's functional economic areas based on actual inter-firm linkages. The result shows that there are six to seven economic blocs in the networks as of 2018. In particular, one huge economic bloc is formed integrating the Seoul metropolitan area, Chungcheong, and Gangwon provinces. Meanwhile, North Jeolla and South Jeolla provinces form two economic blocs separately rather than being tied up in one bloc due to the low frequency of transactions between each other. The two big economic blocs of Daegu-Gyeongbuk and Busan-Gyeongnam exist, and interestingly, Ulsan, Gyeongju, and Pohang form a separate middle-sized bloc across the administrative boundaries. The results reveal that the future balanced national development policies should be implemented based on functional economic areas derived from empirical data.

• Korean Journal of Optics and Photonics
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• v.16 no.3
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• pp.209-216
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• 2005

A new second generation advanced thermal imager, which can be used for battle tank sight has been developed by ADD. This system uses a $480\times6$ TDI HgCdTe detector, operating in the $7.7-10.3{\mu}m$ wavelength made by Sofradir. The IR optics has dual field of views such as $2.67\times2^{\circ}$ in NFOV and $10\times7.5^{\circ}$ in WFOV. And also, this optics is used for athermalization of the system. It is certain that our sensor can be used in wide temperature range without any degradation of the system performance. The scanning system to be able to display 470,000 pixels is developed so that the pixel number is greatly increased comparing with the first generation thermal imaging system. In order to correct non-uniformity of detector arrays, the two point correction method has been developed by using the thermo electric cooler. Additionally, to enhance the image of low contrast and improve the detection capability, we have proposed the new technique of histogram processing being suitable for the characteristics of contrast distribution of thermal imagery. Through these image processing techniques, we obtained the highest quality thermal image. The MRTD of the LWIR thermal sight shows good results below 0.05K at spatial frequency 2 cycles/mrad at the narrow field of view.

• Journal of Food Hygiene and Safety
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• v.38 no.4
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• pp.202-210
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• 2023

To analyze the pesticide residues in commercial bee pollen products in South Korea, 61 samples were collected and screened for 339 pesticides. Results revealed that approximately 34% (>LOQ) of samples were contaminated with at least one pesticide. The pesticide residue detection rates of domestic and imported samples were 31% and 44%, respectively. Furthermore, the pesticide residue detection rate of online distribution (60%) was higher than that of offline distribution (27%). Fifteen pesticides were discovered in bee pollen, and pendimethalin, chlorfenvinphos, chlorpyrifos, and fluazinam were detected in 7, 6, 3, and 2 order of frequency, respectively. Even though its concentration was low, chlorfenvinphos which is banned in food crops in the United States, European Union, and Korea, was detected in bee pollen samples commonly. Therefore, continuous investigation of pesticide residues in bee pollen products and their acceptance criteria is required for safety.

• Journal of Biomedical Engineering Research
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• v.45 no.3
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• pp.128-137
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• 2024

It is necessary to develop a pulsatile Extracorporeal Membrane Oxygenator (p-ECMO) with counter-pulsation control(CPC), which ejects blood during the diastolic phase of the heart rather than the systolic phase, due to the known issues with conventional ECMO causing fatal complications such as ventricular dilation and pulmonary edema. A promising method to simultaneously detect the pulsations of the heart and p-ECMO is to analyze blood pressure waveforms using deep neural network technology(DNN). However, the accurate detection of cardiac rhythms by DNNs is challenging due to various noises such as pulsations from p-ECMO, reflected waves in the vessels, and other dynamic noises. This study aims to evaluate the accuracy of DNNs developed for CPC in p-ECMO, using human-like blood pressure waveforms reproduced in an in-vitro experiment. Especially, an experimental setup that reproduces reflected waves commonly observed in actual patients was developed, and the impact of these waves on DNN judgments was assessed using a multiple DNN (m-DNN) that provides accurate determinations along with a separate index for heartbeat recognition ability. In the experimental setup inducing reflected waves, it was observed that the shape of the blood pressure waveform became increasingly complex, which coincided with an increase in harmonic components, as evident from the Fast Fourier Transform results of the blood pressure wave. It was observed that the recognition score (RS) of DNNs decreased in blood pressure waveforms with significant harmonic components, separate from the frequency components caused by the heart and p-ECMO. This study demonstrated that each DNN trained on blood pressure waveforms without reflected waves showed low RS when faced with waveforms containing reflected waves. However, the accuracy of the final results from the m-DNN remained high even in the presence of reflected waves.

• Journal of Korea Water Resources Association
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• v.54 no.8
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• pp.577-587
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• 2021

Drought is generally considered to be a natural disaster caused by accumulated water shortages over a long period of time, taking months or years and slowly occurring. However, climate change has led to rapid changes in weather and environmental factors that directly affect agriculture, and extreme weather conditions have led to an increase in the frequency of rapidly developing droughts within weeks to months. This phenomenon is defined as 'Flash Drought', which is caused by an increase in surface temperature over a relatively short period of time and abnormally low and rapidly decreasing soil moisture. The detection and analysis of flash drought is essential because it has a significant impact on agriculture and natural ecosystems, and its impacts are associated with agricultural drought impacts. In South Korea, there is no clear definition of flash drought, so the purpose of this study is to identify and analyze its characteristics. In this study, flash drought detection condition was presented based on the satellite-derived drought index Evaporative Stress Index (ESI) from 2014 to 2018. ESI is used as an early warning indicator for rapidly-occurring flash drought a short period of time due to its similar relationship with reduced soil moisture content, lack of precipitation, increased evaporative demand due to low humidity, high temperature, and strong winds. The flash droughts were analyzed using hydrometeorological characteristics by comparing Standardized Precipitation Index (SPI), soil moisture, maximum temperature, relative humidity, wind speed, and precipitation. The correlation was analyzed based on the 8 weeks prior to the occurrence of the flash drought, and in most cases, a high correlation of 0.8(-0.8) or higher(lower) was expressed for ESI and SPI, soil moisture, and maximum temperature.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.3
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• pp.48-60
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• 2007

In previous researches for iris feature extraction, they transform a original iris image into rectangular one by stretching and interpolation, which causes the distortion of iris patterns. Consequently, it reduce iris recognition accuracy. So we are propose the method that extracts iris feature by using polar coordinates without distortion of iris patterns. Our proposed method has three strengths compared with previous researches. First, we extract iris feature directly from polar coordinate circular iris image. Though it requires a little more processing time, there is no degradation of accuracy for iris recognition and we compares the recognition performance of polar coordinate to rectangular type using by Hamming Distance, Cosine Distance and Euclidean Distance. Second, in general, the center position of pupil is different from that of iris due to camera angle, head position and gaze direction of user. So, we propose the method of iris feature detection based on polar coordinate circular iris region, which uses pupil and iris position and radius at the same time. Third, we overcome override point from iris patterns by using polar coordinates circular method. each overlapped point would be extracted from the same position of iris region. To overcome such problem, we modify Gabor filter's size and frequency on first track in order to consider low frequency iris patterns caused by overlapped points. Experimental results showed that EER is 0.29%, d' is 5,9 and EER is 0.16%, d' is 6,4 in case of using conventional rectangular image and proposed method, respectively.

• Geophysics and Geophysical Exploration
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• v.2 no.1
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• pp.33-42
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• 1999

AVO and complex trace analyses mainly used to characterize natural gas reservoir were tested in this paper for a possible application to detection of major geological discontinuities such as fracture zones. The test data used in this study were calculated by utilizing a viscoelastic numerical program which was based on the generalized Maxwell body for a horizontal fracture model. In AVO analysis of a horizontal fracture zone, p-wave reflection appears to be variant depending upon the acoustic-impedence contrast and the offset distance. The fracture zone is also effectively clarified both in gradient stack and range-limited stack in which fracture zone reflection is attenuated with the increasing offset distance. In complex attribute plots (instantaneous amplitude, frequency, and phase), the top and bottom of the fracture Tone are characterized by a zone of strong amplitudes and an event of the same phase. Low frequency characteristics appear at the fracture zone and the underneath. Amplitude attenuation and waveform dispersion are dependent on Q-contrast between the fracture zone and the surrounding media. They were properly compensated by optimum inverse Q-filtering.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.99-108
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• 2015

The embedded microcontroller which is operated by the logic gates synchronized on the clock pulse, is gradually used as main controller of mission-critical systems. Severe electrical situations such as high voltage/frequency surge may cause malfunctioning of the clock source. The tolerant system operation is required against the various external electric noise and means the robust design technique is becoming more important issue in system clock failure problems. In this paper, we propose on-chip backup clock change architecture for the automatic clock failure detection. For the this, we adopt the edge detector, noise canceller logic and glitch-free clock changer circuit. The implemented edge detector unit detects the abnormal low-frequency of the clock source and the delay chain circuit of the clock pulse by the noise canceller can cancel out the glitch clock. The externally invalid clock source by detecting the emergency status will be switched to back-up clock source by glitch-free clock changer circuit. The proposed circuits are evaluated by Verilog simulation and the fabricated IC is validated by using test equipment electrical field radiation noise