• 전기전자학회논문지
• /
• 제24권4호
• /
• pp.1011-1016
• /
• 2020

We propose a framework called Stacked Gated Recurrent Unit - Infrequent Residual Analysis (SG-IRA) that detects anomalies in time-series data that can be trained on streams of raw sensor data without any pre-labeled dataset. To enable such unsupervised learning, SG-IRA includes an estimation model that uses a stacked Gated Recurrent Unit (GRU) structure and an analysis method that detects anomalies based on the difference between the estimated value and the actual measurement (residual). SG-IRA's residual analysis method dynamically adapts the detection threshold from the population using frequency analysis, unlike the baseline model that relies on a constant threshold. In this paper, SG-IRA is evaluated using the industrial control systems (ICS) datasets. SG-IRA improves the detection performance (F1 score) by 5.9% compared to the baseline model.

• 대한물리의학회지
• /
• 제17권2호
• /
• pp.11-20
• /
• 2022

PURPOSE: This study investigated the immediate effects of gluteus medius strengthening training and relaxation therapy on the static balance, muscle strength asymmetry, and proprioception. METHODS: In this research, 38 healthy adults were assigned randomly to strengthening groups (SG) and relaxation groups (RG). The static balance, muscle strength asymmetry, and proprioception were measured as a pre-measurement. The same measurements were performed after the intervention and follow-up. An independent sample t-test was used to compare each group, and one-way repeated ANOVA was used to compare the changes within the group. RESULTS: In the static balance, the comparison between groups SG was more significant than RG, and only SG showed significant differences in the intra-group comparisons. There was no significant difference in muscle strength asymmetry between SG and RG. On the other hand, the comparison within the group revealed only SG to be significant. In proprioception, SG produced more significant results than RG, and only SG had significant values in the within-group comparison. CONCLUSION: Strengthening training affects the changes in static balance, muscle strength asymmetry, and proprioception.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제9권1호
• /
• pp.20-28
• /
• 2001

In order to predict thermodynamic performance of refrigeration system, it is required to know the oil concentration of the refrigerant/oil mixture. The current method is to extract the working mixture and then to measure the oil weight. In this study, oil concentration is measured in si.tu way without any extraction of the working fluid. Based on the measurement, a working equation is presented as follows, C=a +b x t +c x $t^2$ +(d + e x t +f x $t^2$) x SG. C is oil concentration, t is temperature($^{\circ}C). SG Is specific gravity of mixture and a~f is coefficients The oil concentration ranges over 0~l2 wt% and the temperature ranges over 20~50$^{\circ}C. The specific gravity and temperature are measured using the on-line densimeter and thermometer. This working equation enables to predict the oil concentration without any extraction of the mixture. This equation can be applied for R-12/Naphthenic oil and R-134a/P0E oil liquid mixtures.

• 설비공학논문집
• /
• 제11권1호
• /
• pp.31-37
• /
• 1999

In order to predict thermodynamic performance of refrigeration system, it is required to know the oil concentration of the refrigerant/oil mixture. The current method to measure the oil concentration is to extract the working mixture and then to measure the oil weight. However, it is Quite necessary to estimate oil concentration without any extraction of the working fluid. In this study a new method and working equation is presented as follows. It is based on the measurement of spedific gravity and temperature : $$C=a+b{\times}t+c{\times}t^2+(d+e{\times}t+f{\times}t^2){\times}SG$$ C is oil concentration, t is temperature($^{\circ}C$), SG is specific gravity of mixture and a~f is coefficients. The oil concentration ranges over 0~12 wt% and the temperature ranges over $20{\sim}50^{\circ}C$. The specific gravity and temperature are measured using the on-line densimeter and thermometer. This working equation enables to predict the oil concentration without any extraction of the mixture. This equation can be applied for R-12/Naphthenic oil and R-134a/POE oil oiquid mixtures.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제8권2호
• /
• pp.80-88
• /
• 2000

In order to predict thermodynamic performance of refrigeration system, it is required to know the oil concentration of the refrigerant/oil mixture. The current method is to extract the working mixture and then to measure the oil weight. In this study, oil concentration is measured in si.tu way without any extraction of the working fluid. Based on the measurement, a working equation is presented as follows, C=a +b x t +c x $t^2$ +(d + e x t +f x $t^2$) x SG. C is oil concentration, t is temperature($^{\circ}C). SG Is specific gravity of mixture and a~f is coefficients The oil concentration ranges over 0~l2 wt% and the temperature ranges over 20~50$^{\circ}C. The specific gravity and temperature are measured using the on-line densimeter and thermometer. This working equation enables to predict the oil concentration without any extraction of the mixture. This equation can be applied for R-12/Naphthenic oil and R-134a/P0E oil liquid mixtures.

• Nuclear Engineering and Technology
• /
• 제41권10호
• /
• pp.1315-1322
• /
• 2009

The present article is concerned with the application of an electrochemical noise (EN) monitoring technique to analyze the initiation and propagation of Pb-assisted stress corrosion cracking (SCC) of an Alloy 600 material in a simulated environment of a steam generator (SG) sludge pile at high temperatures. A typical increase of electrochemical current noise (ECN) and electrochemical potential noise (EPN) was frequently recorded from the EN measurement in a caustic solution with such impurities as PbO and CuO, indicating that there are localized corrosion events occurring. With the aid of microscopic and spectral analyses, the EN data involving information on such stochastic processes as uniform corrosion and the initiation and propagation of SCC, were analyzed based on a stochastic theory.

• 한국초전도ㆍ저온공학회논문지
• /
• 제13권4호
• /
• pp.14-17
• /
• 2011

The evaluation of the electromechanical properties of HTS CC tapes is one of the foremost procedures to be done to ensure the applicability of superconducting wires to electric devices. A precise measurement of the stress and strain is important in deriving the mechanical properties under operating environment. Up to now, there is no standard test method yet for the electromechanical property evaluation of HTS tapes under self field and external magnetic field although there are already reports on the different devices used to evaluate these properties. Strain can be measured by adopting a strain gauge or a high resolution double extensometer. In this study, strain effect on $I_c$ in HTS CC tapes under magnetic fields was evaluated. Comparison of advantages and setback of strain measuring devices were discussed. In addition, a dual strain measurement system using both the SG and extensometer may be practical to lessen the burden in case one of the measuring devices does not work well.

• 한국전자통신학회논문지
• /
• 제18권1호
• /
• pp.23-28
• /
• 2023

자동전력량 측정이 가능한 AMI(: Advanced Metering Infrastructure)의 설치 비율은 전국적으로 43% 미만이고 특히 지역 기준인 경우에는 10.5%로 매우 열악한 상태이다. 따라서 스마트그리드를 위해서는 전력량계의 자동 정보 기록이 필요하므로 이를 위해서 기존 전력계량계를 개선하여 원격검침 및 사용 제어가 가능한 시스템 개발이 필요하다. 본 논문에서는 기존 전력량계를 AMI기능이 가능하게 하려면 IoT 및 AI를 이용하여 스마트 그리드 핵심인 AMI를 위한 기존 전력 계량기의 원격검침 및 제어 기술 개발을 수행하였다. 주요 연구 내용은 SG를 위한 전력계량기 감지 장치로 변환하기 위하여 Tensorflow와 Open-cv를 이용하여 숫자를 인식하였고, SG를 위한 전력계량기 원격검침 기능 테스트를 위해서는 Intel-Edson 하드웨어와 연동하여 장치를 구성하여 성능을 확인하였다.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2022년도 추계학술대회
• /
• pp.546-549
• /
• 2022

자동전력량 측정이 가능한 AMI (advanced metering infrastructure)의 설치 비율은 전국적으로 43% 미만이고 특히 지역 기준인 경우에는 10.5%로 매우 열악한 상태이다. 따라서 스마트그리드를 위해서는 전력량계의 자동 정보 기록이 필요하므로 이를 위해서 기존 전력계량계를 개선하여 원격검침 및 사용 제어가 가능한 시스템 개발이 필요하다. 본 논문에서는 기존 전력량계를 AMI기능이 가능하게 하려면 IoT 및 AI를 이용하여 스마트 그리드 핵심인 AMI를 위한 기존 전력 계량기의 원격검침 및 제어 기술 개발을 수행하였다. 주요 연구 내용은 SG를 위한 전력계량기 감지 장치로 변환하기 위하여 Tensorflow와 Open-cv를 이용하여 숫자를 인식하였고, SG를 위한 전력계량기 원격검침 기능 테스트를 위해서는 Intel-Edson 하드웨어와 연동하여 장치를 구성하여 성능을 확인하였다.

• 대한원격탐사학회지
• /
• 제21권1호
• /
• pp.31-49
• /
• 2005

We first review some history of the Global Geodynamics Project (GGP), particularly in the progress of ground-satellite gravity comparisons. The GGP Satellite Project has involved the measurement of ground-based superconducting gravimeters (SGs) in Europe for several years and we make quantitative comparisons with the latest satellite GRACE data and hydrological models. The primary goal is to recover information about seasonal hydrology cycles, and we find a good correlation at the microgal level between the data and modeling. One interesting feature of the data is low soil moisture resulting from the European heat wave in 2003. An issue with the ground-based stations is the possibility of mass variations in the soil above a station, and particularly for underground stations these have to be modeled precisely. Based on this work with a regional array, we estimate the effectiveness of future SG arrays to measure co-seismic deformation and silent-slip events. Finally we consider gravity surveys in volcanic areas, and predict the accuracy in modeling subsurface density variations over time periods from months to years.