• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.1
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• pp.98-105
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• 2007

In this paper, we propose a timing detector using suboptimal maximum likelihood method. The proposed method has an simple reference signal generator. Additionally, timing detector's gain of the proposed method is the same to Early-Late gate and ML method. We reveal that tracking range of time tracker is narrow because of using data-decision, that is, tracking range is ${\pm}0.06ns$ for the 4-order Gaussian monocycle with 0.7ns pulse width. Therefore we can find that searcher must have very accurate acquisition procedure. When estimating a performance of time tracker, we consider a jitter in transmitter and receiver's pulse generation process as well as background noise. By using computer simulation, we propose mean/variance of timing detector and tracking process. Also we consider a mobility in tracking process, i.e., timing error modeled ramp function. In order to propose a performance of time tracker, we consider only one correlation demodulator.

• Journal of the Korean Society of Systems Engineering
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• v.18 no.2
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• pp.75-93
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• 2022

Machine learning (ML) data-driven meta-model is proposed as a surrogate model to reduce the excessive computational cost of the physics-based model and facilitate the real-time prediction of a nuclear power plant's transient response. To forecast the transient response three machine learning (ML) meta-models based on recurrent neural networks (RNNs); specifically, Long Short Term Memory (LSTM), Gated Recurrent Unit (GRU), and a sequence combination of Convolutional Neural Network (CNN) and LSTM are developed. The chosen accident scenario is a control element assembly withdrawal at power concurrent with the Loss Of Offsite Power (LOOP). The transient response was obtained using the best estimate thermal hydraulics code, MARS-KS, and cross-validated against the Design and control document (DCD). DAKOTA software is loosely coupled with MARS-KS code via a python interface to perform the Best Estimate Plus Uncertainty Quantification (BEPU) analysis and generate a time series database of the system response to train, test and validate the ML meta-models. Key uncertain parameters identified as required by the CASU methodology were propagated using the non-parametric Monte-Carlo (MC) random propagation and Latin Hypercube Sampling technique until a statistically significant database (181 samples) as required by Wilk's fifth order is achieved with 95% probability and 95% confidence level. The three ML RNN models were built and optimized with the help of the Talos tool and demonstrated excellent performance in forecasting the most probable NPP transient response. This research was guided by the Systems Engineering (SE) approach for the systematic and efficient planning and execution of the research.

• Journal of the Korean Society of Systems Engineering
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• v.4 no.2
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• pp.1-13
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• 2008

The development of hull curved plate forming automation system in ship production field begins from the need of stakeholders such as enterprise organization, who need the reduction of cost and time and improvement of productivity, and end users who work for this production process. Even though hull curved plate forming automation system has small scale, it is reasonable to consider the system as an interdisciplinary system, because the system includes all of hardware, software, human and information and has a specified objective to be performed. In this paper, introduction of 4 leading Model-Based Systems Engineering (MBSE)methodologies is described and SysML(Systems Modeling Language), which is designed to analyze, specify, design, and verify complex systems, is introduced in order to support those methodologies. Especially, SysML is applied to system modeling of hull curved plate forming automation system and focused on. The structure diagrams and behavior diagrams based on operational context of the automation system are used to make system architecture. The performed application of SysML to the hull curved plate forming automation system shows an example of applying SysML to the development of other autonomous systems in ship production domain.

• Journal of Korea Multimedia Society
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• v.8 no.9
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• pp.1153-1162
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• 2005

In this paper, we developed an XML Document Data Synchronization System for java(XDS4j) based on both SyncML(Synchronization Markup Language) framework Sync4j and embedded database system Berkeley DB XML. Because most existing data synchronization systems are based on file systems, data synchronization times at Fast Sync in those systems are very delayed. In the XDS4j, however, XML documents data produced at SyncML client and SyncML server are managed by embedded database system, and also synchronization time at Fast Sync is reduced because only partial elements are accessed by applying to XPath.

• Journal of Yeungnam Medical Science
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• v.9 no.2
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• pp.396-406
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• 1992

Various susceptibility tests have been used to determine minimal inhibition concentration(MIC) of dermatophytes. They have limitations to apply practically because they need long time to determine MIC. Authors examined MIC of T. rubrum to ketoconazole and itraconazole using 96-well microplate and 24-well macroplate by method of Granade and Artis and tried to check the possibility of this method on clinical application. Nine strains of T. rubrum from patients with dermatophytosis were used. Evaluations of the factors affecting MIC were also tried. The results were as follows. 1. Effect of inoculation density on determination time and MIC : Determination of MIC were possible in 4th days after inoculation at higher inoculation density Caborbance 2.0, 1.0) compared to 6th days at lower inoculation density(absorbance 0.5, 0.25). 2. Effect of incubation temperature on MIC : When incubating at $37^{\circ}C$, MIC were below 0.006-$0.04{\mu}g/ml$ to ketokckonazole and below 0.006-$0.04{\mu}g/ml$ to itraconazole while at $25^{\circ}C$ 0.08-$5.68{\mu}g/ml$ to ketoconazole and 0.006-$0.71{\mu}g/ml$ to itraconazole. Significant reduction of MIC was observed at $37^{\circ}C$ compared to $25^{\circ}C$. 3. Effect of container size on determination time and MIC : When incubating in 96-well microplate and 24-well macroplate, determination of MIC was possible in 4th to 6th days after inoculation in broth-containig 96-well microplate compared to 8th to 12th days in broth-containing 24-well macroplate. But no difference in MIC was observed between different container size. 4. Effect of media on MIC : When using broth as media, MIC were below 0.006-$5.68{\mu}g/ml$ to ketoconazole, below 0.006-$0.36{\mu}g/ml$ to itraconazole in broth-containg 24-well macroplate. When using agar as media, MIC were below 0.006-$5.68{\mu}g/ml$ to ketoconzole, below 0.006-$5.68{\mu}g/ml$ to intraconzole in agar-containing 24-well macroplate. There was slight increase of MIC with agar media compared to broth media. 5. These findings confirm that determination of MIC of dermatophtes by method of Granade and Artis is fast and simple technique for antifungal susceptibility test.

• Investigative Magnetic Resonance Imaging
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• v.16 no.1
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• pp.31-39
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• 2012

Purpose : To determine the optimal combination of commercially available superparamagnetic iron oxide (SPIO) nanoparticles with transfection agents (TA). Materials and Methods: Protamine sulfate (Pro) and poly-L-lysin (PLL) were incubated with ferumoxide and ferucarbotran in human mesenchymal stem cells at various concentrations, and cellular viability were evaluated. Cellular iron uptake was qualitatively and quantitatively evaluated. Cell visibility was assessed via MR imaging and the T2-relaxation time was calculated. Results: The cellular viabilities with ferucarbotran were more significantly decreased than those with ferumoxide (p < 0.05). Iron uptake with ferumoxide was significantly higher than that for those with with ferucarbotran. The T2-relaxation time was observed to be shorter with ferumoxide in comparison to those with ferucarbotran (p < 0.05). Ferumoxide at a concentration of 25 ${\mu}g$/ml in combination with either Pro or PLL at a concentration of 3.0 ${\mu}g$/ml did not adversely impact cell viability, maximized iron uptake, and exhibited a lower T2-relaxation time in comparison to other combinations. Conclusion: Stem cells with ferumoxide exhibited a higher cellular viability and iron uptake in comparison to ferucarbotran-treated stem cells. A 25 ${\mu}g$/ml of ferumoxide with a 3.0 ${\mu}g$/ml of TA is sufficient to label mesenchymal stem cells.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.37 no.4
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• pp.272-277
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• 2011

Purpose: The aim of this study was to compare the estimated blood loss and determine the change in hemoglobin depending on the combination of each orthognathic surgery. Subjects and Methods: The subjects of this study were patients who underwent orthognathic surgery among those diagnosed with a dentofaical deformity in Mok-Dong hospital, Ewha Womans University from 2002 to 2009. One hundred patients (men - 36, women - 64, mean age of $24.5{\pm}4.6$) participated in the study and were divided into four groups (group 1 - bilateral sagittal ramus osteotomy [BSSRO], group 2 - BSSRO+Genioplasty, group 3 - Lefort 1+BSSRO+genioplasty, group 4 - anterior segmental osteotomy on maxilla and mandible). A comparative study on the estimated blood loss (EBL), operation time, peri-operative changes in hemoglobin was performed using anesthesia records. The results were analyzed statistically using a Mann-Whitney U-test and Spearman's Rho test - SPSS 12.0 (SPSS Inc. Chicago, IL, USA). Results: In group 1 (BSSRO), the mean EBL, operation time and change in hemoglobin was $394.43{\pm}52.69$ ml, $184{\pm}42.33$ minutes, and 1.43, respectively, In group 2 (BSSRO+genioplasty), it was $556.32{\pm}63.42$ ml, $231{\pm}37.45$ minutes, and 1.80, respectively. In group 3 (Lefort 1+BSSRO+Genioplasty), it was $820.55{\pm}105.54$ ml, $320{\pm}15.41$ minutes, and 2.73, respectively. In group 4 (segmental osteotomy), it was $1025.39{\pm}160.21$ ml, $355{\pm}20.10$ minutes, and 3.33, respectively. In particular, in group 3, significant differences were observed depending on the method of the orthognathic surgery. The mean EBL in a Lefort 1 osteotomy with advancement was only 687 ml, whereas Lefort 1 osteotomy with canting correction (992 ml), even impaction (764 ml), and posterior nasal spine impaction (100 ml) showed a much higher EBL. Conclusion: From these results, the EBL and peri-operation hemoglobin increased as treatment plans became more complicated and increasing operation time. Safe orthognathic surgery should be performed by applying proper autologous transfusion plans based on the average EBL of each orthognathic surgery type.

• Journal of Life Science
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• v.33 no.1
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• pp.43-49
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• 2023

Houttuynia cordata belongs to the Saururacease family and its leaves, stems, and roots have been used as oriental medicines to treat pneumonia, acute or chronic bronchitis, enteritis, and abscesses and to remove extravasated blood. Recently, the antioxidant, anti-inflammation, antibacterial, and anti-proliferation activities and protection abilities of H. cordata against liver and neuron cell damage have been reported. In this study, ethanol extract and its solvent fractions (fractions of hexane, ethyl acetate, butanol, and water residue) were prepared, and their antithrombosis, antidiabetes, antioxidant, and hemolysis activities were evaluated. The ethyl-acetate fraction of H. cordata (EF-HC) showed the highest polyphenol and flavonoids contents among the fractions and exhibited strong antithrombosis and antioxidant activities. The EF-HC at 5 mg/ml showed 2.09-folds of thrombin time, 2.19-folds of prothrombin time, and 1.69-folds of activated partial thromboplastin time compared to the their solvent control and 30.9, 19.9, and 49.6 ㎍/ml of RC₅₀ against DPPH, ABTS, and nitrite radicals, respectively. Furthermore, the EF-HC did not show any hemolytic activity up to 1 mg/ml, whereas the hexane fraction of H. cordata showed 55% hemolysis at 1 mg/ml. This is the first report of the antithrombosis activity of H. cordata. Our results suggest that quercitirin, hyperoside, orientin, and isoquercitrin in EF-HC are related to its antithrombosis and antioxidant activities and that the EF-HC could be developed as a promising antithrombosis agent.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.6
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• pp.1583-1591
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• 1998

In this paper, we consider the quasi maximum likelihood(quasi-ML) detector which uses antenna arrays in asynchronous time-varing channels. It is shown that the proposed quasi-ml detector can be regarded as a beamformer followed by a decorrelator: a method based on the eigendecomposition of the correlation matrix of the inverse-filtered signal is proposed to estimate the channel vectors. We also show that the proposed algorithm estimates the channel vector within small mismatch loss in severe propagation environment through computer simulations.

• The Korean Journal of Food And Nutrition
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• v.12 no.2
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• pp.191-191
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• 1999

A Purge & Trap Concentrator was used to analyze various volatile organic compounds(VOCs) in wat-er. The object of this study was to observe the purge efficiency of 40 VOCs in water according to the change of parameters (purge time drypurge time sample temperature) and to determine the optimum condition for VOCs using the purge & Trap concentrator interfaced with a narrow capillary connected to a gas chromatography/mass spectrometry. The optimum condition of purge and trap is as follows: purge time at 11min drypurge time at 5min sample temperature at 6$0^{\circ}C$ at constant purge flow (40mol/min) constant desorption flow(20ml/min) desorption temperature(2$25^{\circ}C$) and desorption time (1min) At this analytical condition the detection limits of VOCs was in the range of 0.1~0.5$\mu$g/ml and the purge efficiency of each compound was over 70%.