• Title/Summary/Keyword: Research-based

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Speech Enhancement Using Phase-Dependent A Priori SNR Estimator in Log-Mel Spectral Domain

  • Lee, Yun-Kyung;Park, Jeon Gue;Lee, Yun Keun;Kwon, Oh-Wook
    • ETRI Journal
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    • v.36 no.5
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    • pp.721-729
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    • 2014
  • We propose a novel phase-based method for single-channel speech enhancement to extract and enhance the desired signals in noisy environments by utilizing the phase information. In the method, a phase-dependent a priori signal-to-noise ratio (SNR) is estimated in the log-mel spectral domain to utilize both the magnitude and phase information of input speech signals. The phase-dependent estimator is incorporated into the conventional magnitude-based decision-directed approach that recursively computes the a priori SNR from noisy speech. Additionally, we reduce the performance degradation owing to the one-frame delay of the estimated phase-dependent a priori SNR by using a minimum mean square error (MMSE)-based and maximum a posteriori (MAP)-based estimator. In our speech enhancement experiments, the proposed phase-dependent a priori SNR estimator is shown to improve the output SNR by 2.6 dB for both the MMSE-based and MAP-based estimator cases as compared to a conventional magnitude-based estimator.

″Issues in designing a Knowledge-based system to support process modeling″

  • Suh, Eui-Ho;Kim, Suyeon
    • Proceedings of the Korean Operations and Management Science Society Conference
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    • 2001.10a
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    • pp.50-54
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    • 2001
  • Information systems development entails planning, analysis, design and construction phases. The analysis phase identifying user requirements is the most important of these phases. Since unidentified defects in the early phase causes increased work and costs as development proceeds, the quality of analysis results affects the quality of the resultant system. Major tasks in the analysis phase are data modeling and process modeling. Research on building a knowledge-based system for data modeling have been conducted much, however, not sufficiently for process modeling. As a system environment with high user interaction increases, research on process modeling methods and knowledge- based systems considering such environment are required. In this research, a process modeling framework for information systems with high user interaction is suggested and a knowledge-based system for supporting the suggested framework is implemented. A proposed model consists of the following tasks: event analysis, process analysis, and event/process interaction analysis. Event analysis identifies business events and their responses. Process analysis break down the processes of an enterprise into progressively increasing details. Decomposition begins at the function level and ends when the elementary process level is reached. Event/process interaction analysis verifies the results of process analysis and event analysis. A knowledge-based system for supporting a proposed process modeling framework is implemented in a web-based environment.

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Satellite-based Drought Forecasting: Research Trends, Challenges, and Future Directions

  • Son, Bokyung;Im, Jungho;Park, Sumin;Lee, Jaese
    • Korean Journal of Remote Sensing
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    • v.37 no.4
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    • pp.815-831
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    • 2021
  • Drought forecasting is crucial to minimize the damage to food security and water resources caused by drought. Satellite-based drought research has been conducted since 1980s, which includes drought monitoring, assessment, and prediction. Unlike numerous studies on drought monitoring and assessment for the past few decades, satellite-based drought forecasting has gained popularity in recent years. For successful drought forecasting, it is necessary to carefully identify the relationships between drought factors and drought conditions by drought type and lead time. This paper aims to provide an overview of recent research trends and challenges for satellite-based drought forecasts focusing on lead times. Based on the recent literature survey during the past decade, the satellite-based drought forecasting studies were divided into three groups by lead time (i.e., short-term, sub-seasonal, and seasonal) and reviewed with the characteristics of the predictors (i.e., drought factors) and predictands (i.e., drought indices). Then, three major challenges-difficulty in model generalization, model resolution and feature selection, and saturation of forecasting skill improvement-were discussed, which led to provide several future research directions of satellite-based drought forecasting.

Decreased absorption of midazolam in the stomach due to low pH induced by co-administration of Banha-sasim-tang

  • Jo, Jun Hyeon;Kim, Sun Joo;Nam, Woong Shik;Seung, Eun Ji;Lee, Sangkyu
    • Environmental Analysis Health and Toxicology
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    • v.31
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    • pp.16.1-16.9
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    • 2016
  • Objectives Banha-sasim-tang (BST), which consists of seven different herbs, is one of the most popular herbal formulae for treating gastrointestinal disorders in Eastern Asia. The commonly used herbal medicine is often co-administered with other therapeutic drugs, which raises the possibility of herb-drug interactions and may modify the clinical safety profile of therapeutic drugs. Methods We investigated the potential herb-drug interactions between BST extract and midazolam (MDZ) in mice. The area under the plasma concentration-time curve (AUC) of MDZ and 1'-hydroxymidazolam (1'-OH-MDZ) was evaluated for both oral and intraperitoneal administration of MDZ, following oral administration of BST (0.5 and 1 g/kg). Results It was found that the AUC of MDZ and 1'-OH-MDZ was lower in case of oral administration of MDZ. Administration of BST extract was not associated with hepatic cytochrome P450 activity. BST extract induced a strong reduction in pH and it has been reported that oral mucosal absorption of MDZ is lower at low pH. The decreased absorption rate of MDZ might be caused by the ingredients of BST and may not be related to other factors such as increased excretion of MDZ by P-glycoprotein. Conclusions The altered pharmacokinetics of midazolam caused by co-administration with BST in vivo could be attributed to a decrease in pH and subsequent reduction of MDZ absorption rate.

Synthesis of Polyester-Polyamine Dispersants and Their Carbon Dispersing Properties (폴리에스테르-폴리아민 분산제의 합성 및 카본 분산 특성)

  • Son, Jeong-Mae;Yuk, Jeong-Suk;Lee, Sangjun;Kim, Juhyun;Kim, Nam-Kyun;Shin, Jihoon;Kim, Young-Wun
    • Tribology and Lubricants
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    • v.30 no.4
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    • pp.224-233
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    • 2014
  • We prepared polyester-polyamines to improve the effect of carbon black dispersibility for use in thermal transfer ink, and synthesized polymeric dispersing agents by two-step reactions. In the first step, we made polyester by polycondensing 1,6-hexanediol and adipic acid. The resulting polymers had carboxylic acid, which was linked with polyamine via an acid-base reaction. We then characterized the polyester-polyamine structure by NMR spectroscopy and Fourier transform infrared spectroscopy (FT-IR). We also determined the basic characterizations such as total acid numbers (TAN) (5.0-67.5 mgKOH/g), hydroxyl values (27.1-67.5 mgKOH/g), and molar masses ($M_n=1.6-8.4kg\;mol^{-1}$) for the polyester and total base numbers (TBN) (15.3-57.1 mgKOH/g), hydroxyl values (33.0-79.8 mgKOH/g), and nitrogen contents (1.02-3.48%) for the polyester-polyamine polymers. We thus prepared thermal transfer ink using carbon blacks and the polyester-polyamine dispersing agents, and evaluated the resulting mixtures for printability, adhesive force, storage stability, ink appearance, ink gloss, and processability. These mixtures showed significant dispersibility for carbon black in the ink. Thus, we concluded that the dispersibility of the polymeric materials depended on the polyamine structure and the hydrophilicity-hydrophobicity distribution of the polymeric dispersants.

Synthesis of Conjugated Linoleic Acid Methylester using Heterogeneous Catalysts (불균일계 촉매에 의한 공액 리놀레산 메틸에스테르의 합성)

  • Yuk, Jeong-Suk;Lee, Sang-Jun;Kim, Nam-Kyun;Kim, Young-Wun;Yoon, Byeong-Tae
    • Applied Chemistry for Engineering
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    • v.24 no.3
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    • pp.291-298
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    • 2013
  • Conjugated linoleic acid methylester was synthesized through isomerization of linoleic acid methylester by using heterogeneous catalysts. As for heterogeneous catalysts, Ni supported zeolite type catalysts were used. H zoelite Y (HY) were ion exchanged with KCl aqueous solution to synthesize K zeolite Y (KY), and with impregnation method, Ni supported zeolite catalysts were synthesized. Catalysts were used after pre-treatment by using hydrogen. HY catalysts showed a high conversion at low temperatures; but a low selectivity for conjugation reaction. KY catalysts showed a low conversion at low temperatures; but a similar conversion with HY catalysts at high temperatures while a high selectivity at low temperatures. As a result, 4 wt% Ni/KY720 recorded the high conjugation yield of 63.4% at 220.

A Study on the Development of Automation System for Social Science Research Based on Cloud (클라우드 기반의 사회과학연구 자동화 시스템 개발에 관한 연구)

  • Yoon, Cheolho
    • Information Systems Review
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    • v.17 no.1
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    • pp.217-238
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    • 2015
  • Much of the process in Social Science Research can be expedited with use of an automation systems that can lead to research efficiency and dramatic improvement of the research process. This study proposes use of a social science research automation system based on the cloud, which generates questionnaires, supports data collection, and intuitively processes statistical analyses of the data collected. The Cloud-based Social Science Research Automation System is developed with GNU/GPL-based open source software. We also integrate R for statistical computing to enable advanced statistical analyses such as PLS structural equation modeling, mediate effect analysis, compare between groups, and complete general statistics. The Cloud-based Social Science Research Automation system developed in this study is expected to play an important role in improving the social science research process and in performing the social science studies efficiently.

Characterization of the Interaction between White Ginseng Extract and Selegiline Using Triple Quadrupole-Mass Spectrometry

  • Cho, Pil Joung;Liu, Kwang-Hyeon;Song, Im-Sook;Song, Kyung-Sik;Lee, Sangkyu
    • Mass Spectrometry Letters
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    • v.10 no.2
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    • pp.61-65
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    • 2019
  • Korean ginseng (Panax ginseng Meyer) is a traditional herb used across the world to treat various diseases. Although, red ginseng is this herb's most famous product and has demonstrated diverse pharmacological activities, white ginseng (WG) is another ginseng product that is made fresh and individually regulated in Eastern Asia. Red and white ginseng show different characteristics due to distinct processing steps despite originating from the same plant, and the drug interactions induced by WG have not been well documented. Selegiline is a selective monoamine oxidase (MAO) inhibitor used as an antidyskinetic and antiparkinsonian agent. Here we developed a quantification method for selegiline in mouse plasma using a C8 stationary phase in triple quadrupole-mass spectrometry (LC-MS/MS) with multiple reaction monitoring (MRM). The validated LC-MS/MS method was successfully applied to determine the potential interaction with WG extract (0.1 g/kg/day) pre-administered for 4 weeks. The $AUC_{0-240min}$ of selegiline was altered due to a decrease in the absorption of selegiline with repeated administration of WG extract.

On the Design of Power Supply System for Freight Train Reefer Container Based on Simulation

  • Kim, Joouk;Hwang, Sunwoo;Lee, Jae-Bum;Hwang, Jaemin;Chae, Uri
    • International Journal of Internet, Broadcasting and Communication
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    • v.14 no.3
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    • pp.249-257
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    • 2022
  • In recent years, if we order food by easily accessing the online market with our smartphone, we can receive the product in a fresh state at dawn the next day. Cold chain is an industry that can create high added value because it has both the characteristics of general logistics and sensitivity to temperature. Based on the electrical specifications derived from the reefer container capacity requirement investigation, we proved that power supply to up to 33 reefer containers can be made by using three additional auxiliary power supplies which are applied for freight trains in Korea. In this paper, we conducted a research on a design of power supply system for freight train reefer container based on simulation as a basic research necessary for low-temperature distribution and cold chain construction based on the reefer container railroad. Consequently, the simulation was conducted using the three-phase inverter diagram in PSIM and the SVPWM (3-harmonic injection method) control technique, and it was verified that the required power voltage was satisfied with 622Vdc, which is lower than the input voltage of general SPWM of 718Vdc. The details of this paper could be used as a foundational study for constructing cold chains based on a reefer container dedicated to freight trains in the future.

Development of Guideline for Heuristic Based Usability Evaluation on SaMD (SaMD에 대한 휴리스틱 기반 사용적합성 평가 가이드라인 개발)

  • Jong Yeop Kim;Junghyun Kim;Zero Kim;Myung Jin Chung
    • Journal of Biomedical Engineering Research
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    • v.44 no.6
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    • pp.428-442
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    • 2023
  • In this study, we have a goal to develop usability evaluation guidelines for heuristic-based artificial intelligence-based Software as a Medical Device (SaMD) in the medical field. We conducted a gap analysis between medical hardware (H/W) and non-medical software (S/W) based on ten heuristic principles. Through severity assessments, we identified 69 evaluation domains and 112 evaluation criteria aligned with the ten heuristic principles. Subsequently, we categorized each evaluation domain into five types, including user safety, data integrity, regulatory compliance, patient therapeutic effectiveness, and user convenience. We proposed usability evaluation guidelines that apply the newly derived heuristic-based Software as a Medical Device (SaMD) evaluation factors to the risk management process. In the discussion, we also have proposed the potential applications of the research findings and directions for future research. We have emphasized the importance of the judicious application of AI technology in the medical field and the evaluation of usability evaluation and offered valuable guidelines for various stakeholders, including medical device manufacturers, healthcare professionals, and regulatory authorities.