• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.1
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• pp.107-113
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• 2001

This paper describes dynamic performance analysis of a STATCOM based on 3-level inverter. Major attention is focused on the controller design for 3-level inverter, including regulator design for voltage sharing across the dc link capacitors. A detailed simulation model was developed with Matlab and a scaled hardware model was built and tested to verify the proposed approach. Both simulation and experimental results confirm that the developed controller can regulate the reactive power. The developed controller could be effectively applied to the actual hardware system for STATCOM.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.3
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• pp.198-203
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• 2013

Industry convergence is the inexorable trend, which has become a fundamental concept to understand the industrial dynamics and to develop business strategies. However, most of the previous studies on convergence have dealt with the issues at the macro-level (technology- or industry-level), little attention has been paid to the analysis of convergence at the micro level (firm-level). Recognizing that firms are the principal agents that develop fusion technologies, it is encouraged to help firms to work together for technology convergence. Therefore, this research proposes a collaboration model for SMEs, since SMEs tend to have novel ideas and are flexible enough to make fusion-technology. To do this, we conducted a survey for Korean SMEs and analyzed their successful cases of collaboration, which was used as a basis to develop the model. The research results will help develop strategy or policy to promote the collaboration between SMEs and ultimately to make a fusion-technology.

• International Journal of Computer Science & Network Security
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• v.22 no.3
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• pp.285-291
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• 2022

WSN is the major component for information transfer in IoT environments. Source Location Privacy (SLP) has attracted attention in WSN environments. Effective SLP can avoid adversaries to backtrack and capture source nodes. This work presents a Two-Level Randomized Sector-based Routing (TLRSR) model to ensure SLP in wireless environments. Sector creation is the initial process, where the nodes in the network are grouped into defined sectors. The first level routing process identifies sector-based route to the destination node, which is performed by Ant Colony Optimization (ACO). The second level performs route extraction, which identifies the actual nodes for transmission. The route extraction is randomized and is performed using Simulated Annealing. This process is distributed between the nodes, hence ensures even charge depletion across the network. Randomized node selection process ensures SLP and also avoids depletion of certain specific nodes, resulting in increased network lifetime. Experiments and comparisons indicate faster route detection and optimal paths by the TLRSR model.

• Nutrition Research and Practice
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• v.5 no.3
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• pp.236-245
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• 2011

This study investigated the correlation between consumption of sugar intake by fifth grade students in primary schools and development of Attention Deficit Hyperactivity Disorder (ADHD). A total of 107 students participated, and eight boys and one girl (8.4% of the total) categorized as high risk for ADHD according to diagnostic criteria. There were significant differences in the occupations and drinking habits of the respondents' fathers between the normal group and risk group. In a comparison of students' nutrition intake status with daily nutrition intake standards for Koreans, students consumed twice as much protein as the recommended level, whereas their calcium intake was only 60% of the recommended DRI (dietary reference intake). Regarding intake volume of vitamin C, the normal group posted 143.9% of the recommended DRI, whereas the risk group showed only 65.5% of the recommended DRI. In terms of simple sugar intake from snacks, students in the normal group consumed 58.4 g while the risk group consumed 50.2 g. These levels constituted 12.5% of their total daily volume of sugar intake from snacks, which is higher than the 10% standard recommended by the WHO. In conclusion, children who consumed less sugar from fruit snacks or whose vitamin C intake was less than RI was at increased risks for ADHD (P < 0.05). However, no significant association was observed between total volume of simple sugar intake from snacks and ADHD development.

• Proceedings of the KSRS Conference
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• v.2
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• pp.973-976
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• 2006

The oscillations of the Caspian Sea level represent a result of mutually related hydrometeorological processes. The change in the tendency of the mean sea level variations that occurred in the middle 1970s, when the long-term level fall was replaced by its rapid and significant rise, represents an important indicator of the changes in the natural regime of the Caspian Sea. Therefore, sea level monitoring and long-term forecast of the sea level changes represent an extremely important task. The aim of this presentation is to show the experience of application of satellite altimetry methods to the investigation of seasonal and interannual variability of the sea level, wind speed and wave height, water dynamics, as well as of uplift of the Earth’s crust in different parts of the Caspian Sea and Kara-Bogaz-Gol Bay. Special attention is given to estimates of the Volga River runoff derived from satellite altimetry data. The work is based on the 1992-2005 TOPEX/Poseidon (T/P) and Jason-1 (J-1) data sets.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.497-504
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• 2020

Constructing speaker embeddings in speaker verification is an important issue. In general, a self-attention mechanism has been applied for speaker embedding encoding. Previous studies focused on training the self-attention in a high-level layer, such as the last pooling layer. In this case, the effect of low-level layers is not well represented in the speaker embedding encoding. In this study, we propose Masked Cross Self-Attentive Encoding (MCSAE) using ResNet. It focuses on training the features of both high-level and low-level layers. Based on multi-layer aggregation, the output features of each residual layer are used for the MCSAE. In the MCSAE, the interdependence of each input features is trained by cross self-attention module. A random masking regularization module is also applied to prevent overfitting problem. The MCSAE enhances the weight of frames representing the speaker information. Then, the output features are concatenated and encoded in the speaker embedding. Therefore, a more informative speaker embedding is encoded by using the MCSAE. The experimental results showed an equal error rate of 2.63 % using the VoxCeleb1 evaluation dataset. It improved performance compared with the previous self-attentive encoding and state-of-the-art methods.

• Journal of the Korean Society of Safety
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• v.33 no.2
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• pp.132-137
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• 2018

Compared with general rivers, fluctuations of the water level and the river bed are severe in the tidal river. In hydro-dynamic aspect, such fluctuation gives different river-bed data to us according to observing period. The time-dependent river-bed data and pre-estimation of the Manning's roughness coefficient which is the key factor of numerical modelling induces uncertainty of evaluating the design flood level. Thus it is necessary to pay more attention to calculate the flood level at tidal rivers than at general rivers. In this study, downstream of the Imjin River where is affected by tide of the West Sea selected as a study site. From the numerical modelling, it was shown that the unsteady simulation gave considerable mitigation of the water level from the starting point to 15 km upstream compared to the steady simulation. Either making a detention pond or optional dredging was not effective to mitigate the flood level at Gugok - Majung region where is located in the downstream of the Imjin River. Therefore, a more sophisticated approach is required to evaluate the design flood level estimation before constructive measures adopted in general rivers when establishing the flood control plan in a tidal river.

• Journal of The Korean Society of Clinical Toxicology
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• v.13 no.2
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• pp.55-61
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• 2015

Purpose: Many studies have examined the mechanisms of impaired glucose homeostasis after organophosphate (OP) exposure, however no study has evaluated the clinical utility of blood glucose measurements in patients with OP poisoning. The current study was conducted to evaluate the initial glucose level at presentation and the glycemic variables during the first 3 days after admission as a predictor of mortality. Methods: This retrospective observational case series included 228 patients with a history of OP poisoning. Among other clinical data, information on the initial glucose level at presentation and mean glucose level, delta glucose level, and the presence of a hypoglycemic event during the first 3 days of admission, was collected. Results: Survivors had lower initial glucose levels at presentation and glucose variability during the first 3 days of admission compared to non-survivors. The frequency of hypoglycemic events was higher in non-survivors. In multivariate analysis, the initial glucose level (> 233 mg/dl) was an independent predictor of mortality, along with age. Conclusion: The initial glucose level at presentation can be helpful in prediction of mortality in cases of OP intoxication at bedside. The physician should pay attention to patients with a glucose level >233 mg/dl at presentation after ingestion of OP.

• MALSORI
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• no.59
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• pp.27-51
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• 2006

For speech recognition systems, rejection function as well as decoding function is necessary to improve the reliability. There have been many research efforts on out-of-vocabulary word rejection, however, little attention has been paid on non-target sentence rejection. Recently pronunciation approaches using speech recognition increase the need for non-target sentence rejection to provide more accurate and robust results. In this paper, we proposed filler model method and word/phoneme detection ratio method to implement non-target sentence rejection system. We made performance evaluation of filler model along to word-level, phoneme-level, and sentence-level filler models respectively. We also perform the similar experiment using word-level and phoneme-level word/phoneme detection ratio method. For the performance evaluation, the minimized average of FAR and FRR is used for comparing the effectiveness of each method along with the number of words of given sentences. From the experimental results, we got to know that word-level method outperforms the other methods, and word-level filler mode shows slightly better results than that of word detection ratio method.

• Health Policy and Management
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• v.29 no.4
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• pp.422-430
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• 2019

Background: This study aimed to demonstrate the association between the education level of parents and adolescent depression feeling. Methods: We used the chi-square test and the multiple logistic regression model to analyze the data of the "Korean Youth Health Behavior Survey in 2018" (n=43,220) conducted by the Korea Centers for Disease Control and Prevention. Results: As a result of the analysis, a group whose parents' education level is 'above the university graduation (including the graduation of the college)' had statistically significant experience of depression than a group whose parents' education level is 'high school graduation.' Conclusion: When preparing a policy on adolescent depression feeling, we need to consider the association between the education level of parents and adolescent depression feeling. Especially, a higher level of education of parents needs attention and management to foster positive mental health rather than excessive academic pressure, especially in the parent-child relationship of the same gender.