• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.271-279
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• 2008

In this paper, we investigate interference between short-range radiocommunication devices(SRDs) with frequency hopping spread spectrum(FHSS) and direct sequence spread spectrum(DSSS) methods when they are in the same frequency bands. In order to analyze interference from unwanted emission of SRD with DSSS to that of FHSS, Monte-carlo(MC) simulation method is employed and interference probabilities are calculated. We simulate interference scenarios in accordance with several duty cycles and bandwidths. It is also assumed that the propagation model is free space. The effect of distance between interfering transmitter and victim receiver is analyzed and bit error rate(BER) is simulated. From the interference analysis results, it is shown that duty cycle affects compatibility more than band-width does. Also, we can make sure of the separation distance which satisfies BER criterion when there are only one interfering transmitter and multiple interfering transmitters.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2002.05a
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• pp.195-200
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• 2002

ART (Adaptive Resonance Theory [1]) neural network and its variations perform non-hierarchical clustering by unsupervised learning. We propose a scheme "arboART" for hierarchical clustering by using several ART1.5-SSS networks. It classifies multidimensional vectors as a cluster tree, and finds features of clusters. The Basic idea of arboART is to use the prototype formed in an ART network as an input to other ART network that has looser distance criteria (Ishihara, et al., [2,3]). By sending prototype vectors made by ART to one after another, many small categories are combined into larger and more generalized categories. We can draw a dendrogram using classification records of sample and categories. We have confirmed its ability using standard test data commonly used in pattern recognition community. The clustering result is better than traditional computing methods, on separation of outliers, smaller error (diameter) of clusters and causes no chaining. This methodology is applied to Kansei evaluation experiment data analysis.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1533-1538
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• 2005

We have determined the contents of monosaccharides in the hydrolysates of some yogurt and orange juice products by derivatizing monosaccharides with p-aminobenzoic acid ethyl ester (ABEE). The separation of the ABEE-derivatized monosaccharides was efficiently carried out by HPLC using a microcolumn packed with the Alltima $C_{18}$ stationary phase. The concentrations of monosaccharides were determined based on the measured peak area/height counts. ABEE derivatization of fructose and its detection have never been successfully carried out before this work. In this study, two peaks were observed in a fixed ratio for ABEE-fructose, and the ratio was maintained over a wide range of fructose concentration. In order to prove the validity of the above method, we compared the concentrations of glucose, galactose and fructose determined by ABEE derivatization and UVD (ultraviolet detector) chromatography with those determined by RID (refractive index detector) chromatography without derivatization. The determined concentrations of monosaccharides obtained from the two chromatographic methods were found close to each other within acceptable error ranges.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.32 no.3
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• pp.93-98
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• 2021

Electroencephalography (EEG) measures neural activation due to various cognitive processes. EEG and event-related potentials (ERPs) are widely used in studies investigating psychopathology and neural substrates of psychiatric diseases in children and adolescents. The present study aimed to review recent ERP studies in child and adolescent psychiatry. ERPs are non-invasive methods for studying synaptic functions in the brain. ERP might be a candidate biomarker in child-adolescent psychiatry, considering its ability to reflect cognitive and behavioral functions in humans. For the EEG study of psychiatric diseases in children and adolescents, several ERP components have been used, such as mismatch negativity, P300, error-related negativity (ERN), and reward positivity (RewP). Regarding executive functions and inhibition in patients with attention-deficit/hyperactivity disorder (ADHD), P300 latency, and ERN were significantly different in patients with ADHD compared to those in the healthy population. ERN showed meaningful changes in patients with anxiety disorders, such as generalized anxiety disorder, separation anxiety disorder, and obsessive-compulsive disorder. Patients with depression showed significantly attenuated RewP compared to the healthy population, which was related to the symptoms of anhedonia.

• Analytical Science and Technology
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• v.13 no.3
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• pp.291-296
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• 2000

The SIMFUEL which composition is similar to PWR nuclear spent fuels was dissolved with a acid digestion bomb. An analytical conditions of ICP-AES for the direct determination of molybdenum in the uranium matrices without separation process were investigated. Based on the effect of uranium on molybdenum intensity. the most optimum wavelengths of molybdenum were found to be 202.030 and 203.844 nm. However, the method of standard additions is applied to overcome the effects of changing background caused by analyzing the sample solutions containing high concentration of uranium and the standard calibration solutions. The relative error of two methods, direct and indirect measurements with cation exchange resin separation procedures, was less than 5%. Therefore it was possible for this procedure to directly measure molybdenum in uranium matrices without separation. And this method was also applied to the determination of several percent of molybdenum in a U-Mo alloy.

• Progress in Medical Physics
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• v.13 no.3
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• pp.129-134
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• 2002

The radiosurgery is planned that prescribed dose was irradiated to tumor for obtaining expected remedial value in stereotactic radiosurgery. The planning for many irregular tumor shape requires long computation time and skilled planners. Due to the rapid development in computer power recently, many optimization methods using computer has been proposed, although the practical method is still trial and error type of plan. In this study, many beam variables were considered and many tumor shapes were assumed cylinderical ideal models. Then, beam variables that covered the target within 50％ isodose curve were searched, the result was compared and analysed. The beam variables considered were isocenter separation distance, number of isocenters and collimator size. Dose distributions obtained with these variables were analysed by dose volume histogram(DVH) and dose profile at orthogonal plane. According to the results compared, the use of more isocenters than specified isocenter dosen't improve DVH and dose profile but only increases complexity of plan. The best result of DVH and dose profile are obtainedwhen isocenter separation was 1.0-1.2 in using same number of isocenter.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1460-1463
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• 2003

In this study, plastic detection technique was developed, applying remote sensing technology as a method to extract plastic wastes, which is one of the big causes of concern contributing to environmental destruction. It is possible to extract areas where plastic (including polypropylene and polyethylene) wastes are prominent, using ASTER data by taking advantage of its absorptive characteristics of ASTER/SWIR bands. The algorithm is applicable to define large industrial wastes disposal sites and areas where plastic greenhouses are concentrated. However, the detection technique with ASTER/SWIR data has some research tasks to be tackled, which includes a partial secretion of reference spectral, depending on some conditions of plastic wastes and a detection error in a region mixed with vegetations and waters. Following results were obtained after making comparisons between several detection methods and plastic wastes in different conditions; (a)'spectral extraction method' was suitable for areas where plastic wastes exist separated from other objects, such as coastal areas where plastic wastes drifted ashore. (single plastic spectral was used as a reference for the 'spectral extraction method') (b)On the other hand, the 'spectral extraction method' was not suitable for sites where plastic wastes are mixed with vegetation and soil. After making comparison of the processing results of a mixed area, it was found that applying both 'separation method' using un-mixing and ‘spectral extraction method’ with NDVI masked is the most appropriate method to extract plastic wastes. Also, we have investigated the possibility of reducing the influence of vegetation and water, using ASTER/TIR, and successfully extracted some places with plastics. As a conclusion, we have summarized the relationship between detection techniques and conditions of plastic wastes and propose the practical application of remote sensing technology to the extraction of plastic wastes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.4
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• pp.619-627
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• 2015

This paper presents a speech enhancement method using non-negative matrix factorization (NMF). In the training phase, each basis matrix of source signal is obtained from a proper database, and these basis matrices are utilized for the source separation. In this case, the performance of speech enhancement relies heavily on the basis matrix. The proposed method for which speech basis matrix is made a high reconstruction error for noise signal shows a better performance than the standard NMF which basis matrix is trained independently. For comparison, we propose another method, and evaluate one of previous method. In the experiment result, the performance is evaluated by perceptual evaluation speech quality and signal to distortion ratio, and the proposed method outperformed the other methods.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.1
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• pp.11-18
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• 2022

In order to improve the accuracy of particle tracking prediction techniques near the Korean Strait, this study compared and analyzed a particle tracking model based on a seawater flow numerical model and a machine learning based on a particle tracking model using field observation data. The data used in the study were the surface drifter buoy movement trajectory data observed in the Korea Strait, prediction data by machine learning (linear regression, decision tree) using the tide and wind data from three observation stations (Gageo Island, Geoje Island, Gyoboncho), and prediciton data by numerical models (ROMS, MOHID). The above three data were compared through three error evaluation methods (Correlation Coefficient (CC), Root Mean Square Errors (RMSE), and Normalized Cumulative Lagrangian Separation (NCLS)). As a final result, the decision tree model had the best prediction accuracy in CC and RMSE, and the MOHID model had the best prediction results in NCLS.

• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.310-318
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• 2013

In territorial ecosystem, soil has stored considerable amount of carbon, and it is vulnerable to weakness release much of the carbon to atmosphere. In this study, we have been effort realization and discussion to the error between inter-instruments and measurement methods, time and special variations, gap filling and separation from each source included in soil respiration, used to collect soil respiration data in various ecosystems in Korea. In conclusion, it have to collect calibration data throughout comparison test between methods and instruments because accumulated data from past and accumulating data in present did not calibrated. In predicting change of soil carbon dynamic using the model method, it needs important data such as longterm and short-term data, artificial handling data of major factor, data from various ecosystem, soil texture, soil depth etc. In company with, we should collect highly qualified data through deep consideration of present problems.