• Journal of the Institute of Electronics Engineers of Korea CI
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• v.43 no.6 s.312
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• pp.83-91
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• 2006

Flashlights in video has many problem to detect the scene change because of high difference values from successive frames. In this paper propose the reliable scene change detection algorithms by extracting the flashlights. This paper proposes a robust scene change detection technique that uses the weighted chi-square test and the automated threshold-decision algorithms. The weighted chi-square test can subdivide the difference values of individual color channels by calculating the color intensities according to NTSC standard, and it can detect the scene change by joining the weighted color intensities to the predefined chi-square test which emphasize the comparative color difference values. The automated threshold-decision algorithm uses the difference values of frame-to-frame that was obtained by the weighted chi-square test. At first, The Average of total difference values is calculated and then, another average value is calculated using the previous average value from the difference values, finally the most appropriate mid-average value is searched and considered the threshold value. Experimental results show that the proposed algorithms are effective and outperform the previous approaches.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.277-284
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• 2012

In this study, a heat-transfer performance analysis is carried out for a multi-channel volumetric air receiver for a solar power tower. On the basis of a series of reviews regarding the relevant literature, a calculation process is proposed for the prediction of the wall- and air- temperature distributions of a single channel at given geometric and input conditions. Furthermore, a unique mathematical model of the receiver effectiveness is presented through analysis of the temperature profile. The receiver is made of silicon carbide. A total of 225 square straight channels per module are molded to induce the air flow, and each channel has the dimensions of $2mm(W){\times}2mm(H){\times}0.2mm(t){\times}320mm(L)$. The heat-transfer rate, temperature distribution and effectiveness are presented according to the variation of the channel and module number under uniform irradiation and mass flow rate. The available air outlet temperature applied to the solar power tower should be over $700^{\circ}C$. This numerical model was actually used in the design of a 200 kW-level commercial solar air receiver, and the required number of modules satisfying the thermal performance could be obtained for the specified geometric and input conditions.

• Journal of Physiology & Pathology in Korean Medicine
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• v.33 no.6
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• pp.356-362
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• 2019

Scutellaria baicalensis (SB) has widely used in the treatment for various brain diseases in the field of Oriental medicine. Biofermantation of SB can make major chemical constituents of SB to pass blood-brain barrier easily and to have more potent anti-oxidant ability. There is a little information about the contribution of fermented SB (FSB) to the formation or maintenance of the neural plasticity in the hippocampus. The purpose of this study was to evaluate effects of FSB extract on hydrogen peroxide (H₂O₂) - induced impairments of the induction and maintenance of long-term potentiation (LTP), an electrophysiological marker for the neural plasticity in the hippocampus. From hippocampal slices of rats, the field excitatory postsynaptic potentials (fEPSPs) were evoked by the electrical stimulation to the Schaffer collaterals - commissural fibers in the CA1 areas and LTP by theta-burst stimulation by using 64 - channels in vitro multi-extracellular recording system. In order to induce oxidative stress to hippocampal slices two different concentrations (200, 400 μM) of H₂O₂ were given to the perfused aCSF before and after the LTP induction, respectively. The ethanol extract of FBS with concentration of 25 ㎍/ml, 50 ㎍/ml was diluted in perfused aCSF that had 200 μM H₂O₂, respectively. Oxidative stress by the treatment of H₂O₂ resulted in decrease of the induction rate of LTP in the CA1 area with a dose - dependent manner. However, the ethanol extract of FSB prevented the reduction of the induction rate of LTP caused by H₂O₂ - induced oxidative stress with a dose - dependent manner. These results may support a potential application of FSB to ameliorate impairments of hippocampal dependent neural plasticity or memory caused by oxidative stress.

• Journal of Korea Water Resources Association
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• v.44 no.11
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• pp.875-887
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• 2011

The objective of this study is to develop and evaluate a Korean threshold runoff computation method. The selected study area is the Han-River basin and the stream channels in the study area are divided into 3 parts; natural channel and artificial manmade channel for small mountainous catchments, and main channel for master stream. The threshold runoff criteria for small streams is decided to 0.5 m water level increase from the channel bottom, which is the level that mountain climbers and campers successfully escape from natural flood damage. Threshold runoff values in natural channel of small mountainous area are computed by the results from the regional regression analysis between parameters of basin and stream channel, while those in artificial channel of small mountainous area are obtained from the data of basin and channel characteristics parameter. On the other hand, the threshold runoff values for master channel are used the warning flood level that is useful information for escaping guideline for riverside users. For verification of the threshold runoff computation method proposed in this study, three flash flood cases are selected and compared with observed values, which is obtained from SCS effective rainfall computation. The 1, 3, 6-hour effective rainfall values are greater than the corresponding threshold runoff values represents that the proposed computation results are reasonable.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.148-153
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• 1999

Baikdu-san was a very active volcano during the Cenozoic era and is believed to be formed in late Cenozoic era. Recently it was also reported that there was a major eruption in or around 1002 A.D. and there are evidences which indicate that it is still an active volcano and a potential volcanic hazard. Remote sensing techniques have been widely used to monitor various natural hazards, including volcanic hazards. However, during an active volcanic eruption, volcanic ash can basically cover the sky and often blocks the solar radiation preventing any use of optical sensors. Synthetic aperture radar(SAR) is an ideal tool to monitor the volcanic activities and lava flows, because the wavelength of the microwave signal is considerably longer that the average volcanic ash particle size. In this study we have utilized several sets of SAR data to evaluate the utility of the space-borne SAR system. The data sets include JERS-1(L-band) SAR, and RADARSAT(C-band) data which included both standard mode and the ScanSAR mode data sets. We also utilized several sets of auxiliary data such as local geological maps and JERS-1 OPS data. The routine preprocessing and image processing steps were applied to these data sets before any attempts of classifying and mapping surface geological features. Although we computed sigma nought ($\sigma$$^{0}$) values far the standard mode RADARSAT data, the utility of sigma nought image was minimal in this study. Application of various types of classification algorithms to identify and map several stages of volcanic flows was not very successful. Although this research is still in progress, the following preliminary conclusions could be made: (1) sigma nought (RADARSAT standard mode data) and DN (JERS-1 SAR and RADARSAT ScanSAR data) have limited usefulness for distinguishing early basalt lava flows from late trachyte flows or later trachyte flows from the old basement granitic rocks around Baikdu-san volcano, (2) surface geological structure features such as several faults and volcanic lava flow channels can easily be identified and mapped, and (3) routine application of unsupervised classification methods cannot be used for mapping any types of surface lava flow patterns.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.153-161
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• 2000

This study was carried out to examine the drift of Gammarus sobaegensis by acid stress as pH depression in Oweol creek from April 1996 to October 1996. The behavioral drifting was revealed to the characteristics of G. sobaegensis that is tend to increase as acid stress. And, tolerance level of G. sobaegensis to pH depression was different among the size classes. Individuals belong to small to medium size classes were weak in lower pH. Pattern of response in G. sobaegensis has a lower tolerance to acid stress at below pH 4.0 than above pH 5.0 in the artificial channel and show the possibility as an effective aquatic ecotoxicity test organism. The result of analysis of variance, water temperature (F-ratio : 66.596, p< 0.0005) and the size classes (F-ratio : 71.386, p< 0.0005) except pH level (F-ratio : 353.415, p<0.0005) were showed to the major factor for drift behavior by acid depression. [Gammarus, pH, Drift, Acid stress, Ecotoxicity test].

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.728-739
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• 2020

Using webometric big data, this study examines the diversity of online information sources about the novel coronavirus causing the COVID-19 pandemic. Specifically, it focuses on some 28 countries where confirmed coronavirus cases occurred in February 2020. In the results, the online visibility of Australia, Canada, and Italy was the highest, based on their producing the most relevant information. There was a statistically significant correlation between the hit counts per country and the frequency of visiting the domains that act as information channels. Interestingly, Japan, China, and Singapore, which had a large number of confirmed cases at that time, were providing web data related to the novel coronavirus. Online sources were classified using an N-tuple helix model. The results showed that government agencies were the largest supplier of coronavirus information in cyberspace. Furthermore, the two-mode network technique revealed that media companies, university hospitals, and public healthcare centers had taken a positive attitude towards online circulation of coronavirus research and epidemic prevention information. However, semantic network analysis showed that health, school, home, and public had high centrality values. This means that people were concerned not only about personal prevention rules caused by the coronavirus outbreak, but also about response plans caused by life inconveniences and operational obstacles.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.708-717
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• 2014

In this paper, we present a secret key distribution protocol without resorting to a key management infrastructure targeting at providing a low-complexity distributed solution to wireless network. The proposed scheme extracts a secret key from the random fluctuation of wireless channels. By exploiting time division duplexing transmission, two legitimate users, Alice and Bob can have highly correlated channel gains due to channel reciprocity, and a pair of random bit sequences can be generated by quantizing the channel gains. We propose a novel adaptive quantization scheme that adjusts quantization thresholds according to channel variations and reduces the mismatch probability between generated bit sequences by Alice and Bob. BCH codes, as a low-complexity and pratical approach, are also employed to correct the mismatches between the pair of bit sequences and produce a secret key shared by Alice and Bob. To maximize the secret key extraction rate, the parameters, quantization levels and code rates of BCH codes are jointly optimized.

• The Journal of Internal Korean Medicine
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• v.26 no.2
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• pp.440-452
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• 2005

Objective: In the winter of 2002, severe acute respiratory syndrome(SARS) began to spread throughout the world. More than 5,000 cases were reported in China, including over 1,700 cases in Hong Kong Special Administrative Region(Hong Kong SAR). The total number of cases reported from Canada and Singapore was more than 200. The total number of SARS cases world-wide reached 8,437 with incidences in 29 counties. Mortality from SARS is estimated at $10{\sim}12%$. When the SARS outbreak occurred in China, the State Administration of Traditional Chinese Medicine of China immediately initiated clinical research projects on the use of integrated herbal medicine and Western medicine for treating SARS. and, in Hong Kong SAR, research on the use of herbal medicine for the prevention and treatment of SARS. Reports were released during convalescence. The objective of this study is to overview twelve clinical SARS reports of WHO on the treatment of SARS with herbal medicine and evaluate the efficacy and safety of treatment of SARS with herbal medicine, and further to share experiences and knowledge of the treatment of SARS. Methods: Twelve clinical reports about SARS from the WHO were selected, overviewed and evaluated for efficacy and safety of treatments of SARS. Results and Conclusion: Twelve clinical reports about SARS showed that the integrated treatment may have advantages, and the advantages are reflected in the following findings: Firstly, herbal medicine is not targeted only at a specific etiology or a certain pathological link, but also at the pathological status of the patients at that particular time. Therefore, comprehensive readjustment was made through various angles, targets and channels to restore the balance of the body. Secondly, there are advantages in the differentiation of the disease and the treatment. Based on the various symptoms, herbal medicine enables the physician to adopt the most suitable principle, provide individual treatment, and to administer medicine in accordance with the actual process and nature of the illness. Thirdly, there are advantages in the results of the treatment; herbal medicine can relieve symptoms, promote absorption of lung inflammation, improve the degree of blood oxygen saturation, regulate immunological functions, reduce the required dosage of glucocorticoid and other Western medicines, and reduce case fatality rate, in addition to lowering the cost of treatment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.575-583
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• 2017

Various types of flow patterns around the stepped weir and spillway, such as the skimming flow over such structures and the wave-type flow with a standing undular hydraulic jump and roller downstream of the structures, are developed in open channels. Unsteady three-dimensional numerical simulations are carried out using a hybrid RANS-LES turbulence modeling approach and the volume of fluid method for resolving free surface fluctuations to represent the turbulent flow including the skimming flow and wave-type flow over a stepped weir installed in a rectangular channel. The comparison of numerical results with an existing experimental measurement reveals that the present numerical simulations reasonably well reproduce the turbulent flow passing the stepped weir, in terms of time-averaged velocity profiles at selected locations downstream of the weir, flow topology characterized by the wave-type and skimming flows, the maximum height and length of the standing wave and the length of reattachment of recirculating zone. The numerical result further elucidates the distinct flow behaviors of the wave-type and skimming flow by presenting instantaneous intense variations of free surface and velocity vectors, the distributions of Reynolds shear stress and turbulent kinetic energy and three-dimensional complex features of coherent structures and total pressure distribution.